perf tool: Constify tool pointers

The tool pointer (to a struct largely of function pointers) is passed
around but is unchanged except at initialization. Change parameter and
variable types to be const to lower the possibilities of what could
happen with a tool.

Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Leo Yan <leo.yan@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Sun Haiyong <sunhaiyong@loongson.cn>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20240812204720.631678-4-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

49 files changed, 314 insertions, 316 deletions

diff --git a/tools/perf/arch/x86/util/event.c b/tools/perf/arch/x86/util/event.c
index e65b7dbe27fb..a0400707180c 100644
--- a/tools/perf/arch/x86/util/event.c
+++ b/tools/perf/arch/x86/util/event.c
@@ -15,7 +15,7 @@
 #if defined(__x86_64__)
 
 struct perf_event__synthesize_extra_kmaps_cb_args {
-	struct perf_tool *tool;
+	const struct perf_tool *tool;
 	perf_event__handler_t process;
 	struct machine *machine;
 	union perf_event *event;
@@ -65,7 +65,7 @@ static int perf_event__synthesize_extra_kmaps_cb(struct map *map, void *data)
 	return 0;
 }
 
-int perf_event__synthesize_extra_kmaps(struct perf_tool *tool,
+int perf_event__synthesize_extra_kmaps(const struct perf_tool *tool,
 				       perf_event__handler_t process,
 				       struct machine *machine)
 {
diff --git a/tools/perf/bench/synthesize.c b/tools/perf/bench/synthesize.c
index 7401ebbac100..9b333276cbdb 100644
--- a/tools/perf/bench/synthesize.c
+++ b/tools/perf/bench/synthesize.c
@@ -49,7 +49,7 @@ static const char *const bench_usage[] = {
 
 static atomic_t event_count;
 
-static int process_synthesized_event(struct perf_tool *tool __maybe_unused,
+static int process_synthesized_event(const struct perf_tool *tool __maybe_unused,
 				     union perf_event *event __maybe_unused,
 				     struct perf_sample *sample __maybe_unused,
 				     struct machine *machine __maybe_unused)
diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index 1bfe41783a7c..cc65e6f8f4da 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -279,7 +279,7 @@ static int evsel__add_sample(struct evsel *evsel, struct perf_sample *sample,
 	return ret;
 }
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index c157bd31f2e5..88c131d05186 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -273,7 +273,7 @@ static void compute_stats(struct c2c_hist_entry *c2c_he,
 		update_stats(&cstats->load, weight);
 }
 
-static int process_sample_event(struct perf_tool *tool __maybe_unused,
+static int process_sample_event(const struct perf_tool *tool __maybe_unused,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
diff --git a/tools/perf/builtin-diff.c b/tools/perf/builtin-diff.c
index 57d300d8e570..4c0567882a7a 100644
--- a/tools/perf/builtin-diff.c
+++ b/tools/perf/builtin-diff.c
@@ -388,7 +388,7 @@ struct hist_entry_ops block_hist_ops = {
 	.free   = block_hist_free,
 };
 
-static int diff__process_sample_event(struct perf_tool *tool,
+static int diff__process_sample_event(const struct perf_tool *tool,
 				      union perf_event *event,
 				      struct perf_sample *sample,
 				      struct evsel *evsel,
diff --git a/tools/perf/builtin-inject.c b/tools/perf/builtin-inject.c
index 8f3dd8980da0..283429ccd034 100644
--- a/tools/perf/builtin-inject.c
+++ b/tools/perf/builtin-inject.c
@@ -134,7 +134,7 @@ struct event_entry {
 	union perf_event event[];
 };
 
-static int dso__inject_build_id(struct dso *dso, struct perf_tool *tool,
+static int dso__inject_build_id(struct dso *dso, const struct perf_tool *tool,
 				struct machine *machine, u8 cpumode, u32 flags);
 
 static int output_bytes(struct perf_inject *inject, void *buf, size_t sz)
@@ -149,7 +149,7 @@ static int output_bytes(struct perf_inject *inject, void *buf, size_t sz)
 	return 0;
 }
 
-static int perf_event__repipe_synth(struct perf_tool *tool,
+static int perf_event__repipe_synth(const struct perf_tool *tool,
 				    union perf_event *event)
 {
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
@@ -158,7 +158,7 @@ static int perf_event__repipe_synth(struct perf_tool *tool,
 	return output_bytes(inject, event, event->header.size);
 }
 
-static int perf_event__repipe_oe_synth(struct perf_tool *tool,
+static int perf_event__repipe_oe_synth(const struct perf_tool *tool,
 				       union perf_event *event,
 				       struct ordered_events *oe __maybe_unused)
 {
@@ -166,7 +166,7 @@ static int perf_event__repipe_oe_synth(struct perf_tool *tool,
 }
 
 #ifdef HAVE_JITDUMP
-static int perf_event__drop_oe(struct perf_tool *tool __maybe_unused,
+static int perf_event__drop_oe(const struct perf_tool *tool __maybe_unused,
 			       union perf_event *event __maybe_unused,
 			       struct ordered_events *oe __maybe_unused)
 {
@@ -188,7 +188,7 @@ static int perf_event__repipe_op4_synth(struct perf_session *session,
 	return perf_event__repipe_synth(session->tool, event);
 }
 
-static int perf_event__repipe_attr(struct perf_tool *tool,
+static int perf_event__repipe_attr(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct evlist **pevlist)
 {
@@ -206,7 +206,7 @@ static int perf_event__repipe_attr(struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
-static int perf_event__repipe_event_update(struct perf_tool *tool,
+static int perf_event__repipe_event_update(const struct perf_tool *tool,
 					   union perf_event *event,
 					   struct evlist **pevlist __maybe_unused)
 {
@@ -237,7 +237,7 @@ static int copy_bytes(struct perf_inject *inject, struct perf_data *data, off_t
 static s64 perf_event__repipe_auxtrace(struct perf_session *session,
 				       union perf_event *event)
 {
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
 						  tool);
 	int ret;
@@ -284,7 +284,7 @@ perf_event__repipe_auxtrace(struct perf_session *session __maybe_unused,
 
 #endif
 
-static int perf_event__repipe(struct perf_tool *tool,
+static int perf_event__repipe(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -292,7 +292,7 @@ static int perf_event__repipe(struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
-static int perf_event__drop(struct perf_tool *tool __maybe_unused,
+static int perf_event__drop(const struct perf_tool *tool __maybe_unused,
 			    union perf_event *event __maybe_unused,
 			    struct perf_sample *sample __maybe_unused,
 			    struct machine *machine __maybe_unused)
@@ -300,7 +300,7 @@ static int perf_event__drop(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int perf_event__drop_aux(struct perf_tool *tool,
+static int perf_event__drop_aux(const struct perf_tool *tool,
 				union perf_event *event __maybe_unused,
 				struct perf_sample *sample,
 				struct machine *machine __maybe_unused)
@@ -341,13 +341,13 @@ perf_inject__cut_auxtrace_sample(struct perf_inject *inject,
 	return ev;
 }
 
-typedef int (*inject_handler)(struct perf_tool *tool,
+typedef int (*inject_handler)(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample,
 			      struct evsel *evsel,
 			      struct machine *machine);
 
-static int perf_event__repipe_sample(struct perf_tool *tool,
+static int perf_event__repipe_sample(const struct perf_tool *tool,
 				     union perf_event *event,
 				     struct perf_sample *sample,
 				     struct evsel *evsel,
@@ -372,7 +372,7 @@ static int perf_event__repipe_sample(struct perf_tool *tool,
 	return perf_event__repipe_synth(tool, event);
 }
 
-static int perf_event__repipe_mmap(struct perf_tool *tool,
+static int perf_event__repipe_mmap(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct perf_sample *sample,
 				   struct machine *machine)
@@ -386,7 +386,7 @@ static int perf_event__repipe_mmap(struct perf_tool *tool,
 }
 
 #ifdef HAVE_JITDUMP
-static int perf_event__jit_repipe_mmap(struct perf_tool *tool,
+static int perf_event__jit_repipe_mmap(const struct perf_tool *tool,
 				       union perf_event *event,
 				       struct perf_sample *sample,
 				       struct machine *machine)
@@ -455,7 +455,7 @@ static struct dso *findnew_dso(int pid, int tid, const char *filename,
 	return dso;
 }
 
-static int perf_event__repipe_buildid_mmap(struct perf_tool *tool,
+static int perf_event__repipe_buildid_mmap(const struct perf_tool *tool,
 					   union perf_event *event,
 					   struct perf_sample *sample,
 					   struct machine *machine)
@@ -474,7 +474,7 @@ static int perf_event__repipe_buildid_mmap(struct perf_tool *tool,
 	return perf_event__repipe(tool, event, sample, machine);
 }
 
-static int perf_event__repipe_mmap2(struct perf_tool *tool,
+static int perf_event__repipe_mmap2(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct perf_sample *sample,
 				   struct machine *machine)
@@ -500,7 +500,7 @@ static int perf_event__repipe_mmap2(struct perf_tool *tool,
 }
 
 #ifdef HAVE_JITDUMP
-static int perf_event__jit_repipe_mmap2(struct perf_tool *tool,
+static int perf_event__jit_repipe_mmap2(const struct perf_tool *tool,
 					union perf_event *event,
 					struct perf_sample *sample,
 					struct machine *machine)
@@ -524,7 +524,7 @@ static int perf_event__jit_repipe_mmap2(struct perf_tool *tool,
 }
 #endif
 
-static int perf_event__repipe_buildid_mmap2(struct perf_tool *tool,
+static int perf_event__repipe_buildid_mmap2(const struct perf_tool *tool,
 					    union perf_event *event,
 					    struct perf_sample *sample,
 					    struct machine *machine)
@@ -565,7 +565,7 @@ static int perf_event__repipe_buildid_mmap2(struct perf_tool *tool,
 	return 0;
 }
 
-static int perf_event__repipe_fork(struct perf_tool *tool,
+static int perf_event__repipe_fork(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct perf_sample *sample,
 				   struct machine *machine)
@@ -578,7 +578,7 @@ static int perf_event__repipe_fork(struct perf_tool *tool,
 	return err;
 }
 
-static int perf_event__repipe_comm(struct perf_tool *tool,
+static int perf_event__repipe_comm(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct perf_sample *sample,
 				   struct machine *machine)
@@ -591,7 +591,7 @@ static int perf_event__repipe_comm(struct perf_tool *tool,
 	return err;
 }
 
-static int perf_event__repipe_namespaces(struct perf_tool *tool,
+static int perf_event__repipe_namespaces(const struct perf_tool *tool,
 					 union perf_event *event,
 					 struct perf_sample *sample,
 					 struct machine *machine)
@@ -603,7 +603,7 @@ static int perf_event__repipe_namespaces(struct perf_tool *tool,
 	return err;
 }
 
-static int perf_event__repipe_exit(struct perf_tool *tool,
+static int perf_event__repipe_exit(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct perf_sample *sample,
 				   struct machine *machine)
@@ -712,7 +712,7 @@ static bool perf_inject__lookup_known_build_id(struct perf_inject *inject,
 	return false;
 }
 
-static int dso__inject_build_id(struct dso *dso, struct perf_tool *tool,
+static int dso__inject_build_id(struct dso *dso, const struct perf_tool *tool,
 				struct machine *machine, u8 cpumode, u32 flags)
 {
 	struct perf_inject *inject = container_of(tool, struct perf_inject,
@@ -743,7 +743,7 @@ static int dso__inject_build_id(struct dso *dso, struct perf_tool *tool,
 	return 0;
 }
 
-int perf_event__inject_buildid(struct perf_tool *tool, union perf_event *event,
+int perf_event__inject_buildid(const struct perf_tool *tool, union perf_event *event,
 			       struct perf_sample *sample,
 			       struct evsel *evsel __maybe_unused,
 			       struct machine *machine)
@@ -776,7 +776,7 @@ repipe:
 	return 0;
 }
 
-static int perf_inject__sched_process_exit(struct perf_tool *tool,
+static int perf_inject__sched_process_exit(const struct perf_tool *tool,
 					   union perf_event *event __maybe_unused,
 					   struct perf_sample *sample,
 					   struct evsel *evsel __maybe_unused,
@@ -796,7 +796,7 @@ static int perf_inject__sched_process_exit(struct perf_tool *tool,
 	return 0;
 }
 
-static int perf_inject__sched_switch(struct perf_tool *tool,
+static int perf_inject__sched_switch(const struct perf_tool *tool,
 				     union perf_event *event,
 				     struct perf_sample *sample,
 				     struct evsel *evsel,
@@ -821,7 +821,7 @@ static int perf_inject__sched_switch(struct perf_tool *tool,
 }
 
 #ifdef HAVE_LIBTRACEEVENT
-static int perf_inject__sched_stat(struct perf_tool *tool,
+static int perf_inject__sched_stat(const struct perf_tool *tool,
 				   union perf_event *event __maybe_unused,
 				   struct perf_sample *sample,
 				   struct evsel *evsel,
@@ -866,7 +866,7 @@ static int guest_session__output_bytes(struct guest_session *gs, void *buf, size
 	return ret < 0 ? ret : 0;
 }
 
-static int guest_session__repipe(struct perf_tool *tool,
+static int guest_session__repipe(const struct perf_tool *tool,
 				 union perf_event *event,
 				 struct perf_sample *sample __maybe_unused,
 				 struct machine *machine __maybe_unused)
@@ -1032,7 +1032,7 @@ static struct guest_id *guest_session__lookup_id(struct guest_session *gs, u64 i
 	return NULL;
 }
 
-static int process_attr(struct perf_tool *tool, union perf_event *event,
+static int process_attr(const struct perf_tool *tool, union perf_event *event,
 			struct perf_sample *sample __maybe_unused,
 			struct machine *machine __maybe_unused)
 {
@@ -1160,7 +1160,7 @@ static u64 evlist__first_id(struct evlist *evlist)
 	return 0;
 }
 
-static int process_build_id(struct perf_tool *tool,
+static int process_build_id(const struct perf_tool *tool,
 			    union perf_event *event,
 			    struct perf_sample *sample __maybe_unused,
 			    struct machine *machine __maybe_unused)
@@ -1210,7 +1210,7 @@ static int guest_session__add_build_ids(struct guest_session *gs)
 				  gs);
 }
 
-static int guest_session__ksymbol_event(struct perf_tool *tool,
+static int guest_session__ksymbol_event(const struct perf_tool *tool,
 					union perf_event *event,
 					struct perf_sample *sample __maybe_unused,
 					struct machine *machine __maybe_unused)
@@ -1574,7 +1574,7 @@ static int guest_session__flush_events(struct guest_session *gs)
 	return guest_session__inject_events(gs, -1);
 }
 
-static int host__repipe(struct perf_tool *tool,
+static int host__repipe(const struct perf_tool *tool,
 			union perf_event *event,
 			struct perf_sample *sample,
 			struct machine *machine)
@@ -1647,7 +1647,7 @@ static int host__finished_init(struct perf_session *session, union perf_event *e
  * guest events up to the same time. Finally write out the FINISHED_ROUND event
  * itself.
  */
-static int host__finished_round(struct perf_tool *tool,
+static int host__finished_round(const struct perf_tool *tool,
 				union perf_event *event,
 				struct ordered_events *oe)
 {
@@ -1665,7 +1665,7 @@ static int host__finished_round(struct perf_tool *tool,
 	return perf_event__repipe_oe_synth(tool, event, oe);
 }
 
-static int host__context_switch(struct perf_tool *tool,
+static int host__context_switch(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct machine *machine)
@@ -1719,7 +1719,7 @@ static int evsel__check_stype(struct evsel *evsel, u64 sample_type, const char *
 	return 0;
 }
 
-static int drop_sample(struct perf_tool *tool __maybe_unused,
+static int drop_sample(const struct perf_tool *tool __maybe_unused,
 		       union perf_event *event __maybe_unused,
 		       struct perf_sample *sample __maybe_unused,
 		       struct evsel *evsel __maybe_unused,
diff --git a/tools/perf/builtin-kmem.c b/tools/perf/builtin-kmem.c
index 6fd95be5032b..859ff018eace 100644
--- a/tools/perf/builtin-kmem.c
+++ b/tools/perf/builtin-kmem.c
@@ -955,7 +955,7 @@ static bool perf_kmem__skip_sample(struct perf_sample *sample)
 typedef int (*tracepoint_handler)(struct evsel *evsel,
 				  struct perf_sample *sample);
 
-static int process_sample_event(struct perf_tool *tool __maybe_unused,
+static int process_sample_event(const struct perf_tool *tool __maybe_unused,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
@@ -2061,4 +2061,3 @@ out_delete:
 
 	return ret;
 }
-
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index 71165036e4ca..a3b903cf4311 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1166,7 +1166,7 @@ static void print_result(struct perf_kvm_stat *kvm)
 }
 
 #if defined(HAVE_TIMERFD_SUPPORT) && defined(HAVE_LIBTRACEEVENT)
-static int process_lost_event(struct perf_tool *tool,
+static int process_lost_event(const struct perf_tool *tool,
 			      union perf_event *event __maybe_unused,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -1187,7 +1187,7 @@ static bool skip_sample(struct perf_kvm_stat *kvm,
 	return false;
 }
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
diff --git a/tools/perf/builtin-kwork.c b/tools/perf/builtin-kwork.c
index 56e3f3a5e03a..8ffaa80a2d1d 100644
--- a/tools/perf/builtin-kwork.c
+++ b/tools/perf/builtin-kwork.c
@@ -958,7 +958,7 @@ static int top_sched_switch_event(struct perf_kwork *kwork,
 }
 
 static struct kwork_class kwork_irq;
-static int process_irq_handler_entry_event(struct perf_tool *tool,
+static int process_irq_handler_entry_event(const struct perf_tool *tool,
 					   struct evsel *evsel,
 					   struct perf_sample *sample,
 					   struct machine *machine)
@@ -971,7 +971,7 @@ static int process_irq_handler_entry_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_irq_handler_exit_event(struct perf_tool *tool,
+static int process_irq_handler_exit_event(const struct perf_tool *tool,
 					  struct evsel *evsel,
 					  struct perf_sample *sample,
 					  struct machine *machine)
@@ -1037,7 +1037,7 @@ static struct kwork_class kwork_irq = {
 };
 
 static struct kwork_class kwork_softirq;
-static int process_softirq_raise_event(struct perf_tool *tool,
+static int process_softirq_raise_event(const struct perf_tool *tool,
 				       struct evsel *evsel,
 				       struct perf_sample *sample,
 				       struct machine *machine)
@@ -1051,7 +1051,7 @@ static int process_softirq_raise_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_softirq_entry_event(struct perf_tool *tool,
+static int process_softirq_entry_event(const struct perf_tool *tool,
 				       struct evsel *evsel,
 				       struct perf_sample *sample,
 				       struct machine *machine)
@@ -1065,7 +1065,7 @@ static int process_softirq_entry_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_softirq_exit_event(struct perf_tool *tool,
+static int process_softirq_exit_event(const struct perf_tool *tool,
 				      struct evsel *evsel,
 				      struct perf_sample *sample,
 				      struct machine *machine)
@@ -1167,7 +1167,7 @@ static struct kwork_class kwork_softirq = {
 };
 
 static struct kwork_class kwork_workqueue;
-static int process_workqueue_activate_work_event(struct perf_tool *tool,
+static int process_workqueue_activate_work_event(const struct perf_tool *tool,
 						 struct evsel *evsel,
 						 struct perf_sample *sample,
 						 struct machine *machine)
@@ -1181,7 +1181,7 @@ static int process_workqueue_activate_work_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_workqueue_execute_start_event(struct perf_tool *tool,
+static int process_workqueue_execute_start_event(const struct perf_tool *tool,
 						 struct evsel *evsel,
 						 struct perf_sample *sample,
 						 struct machine *machine)
@@ -1195,7 +1195,7 @@ static int process_workqueue_execute_start_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_workqueue_execute_end_event(struct perf_tool *tool,
+static int process_workqueue_execute_end_event(const struct perf_tool *tool,
 					       struct evsel *evsel,
 					       struct perf_sample *sample,
 					       struct machine *machine)
@@ -1266,7 +1266,7 @@ static struct kwork_class kwork_workqueue = {
 };
 
 static struct kwork_class kwork_sched;
-static int process_sched_switch_event(struct perf_tool *tool,
+static int process_sched_switch_event(const struct perf_tool *tool,
 				      struct evsel *evsel,
 				      struct perf_sample *sample,
 				      struct machine *machine)
@@ -1945,12 +1945,12 @@ static int perf_kwork__report(struct perf_kwork *kwork)
 	return 0;
 }
 
-typedef int (*tracepoint_handler)(struct perf_tool *tool,
+typedef int (*tracepoint_handler)(const struct perf_tool *tool,
 				  struct evsel *evsel,
 				  struct perf_sample *sample,
 				  struct machine *machine);
 
-static int perf_kwork__process_tracepoint_sample(struct perf_tool *tool,
+static int perf_kwork__process_tracepoint_sample(const struct perf_tool *tool,
 						 union perf_event *event __maybe_unused,
 						 struct perf_sample *sample,
 						 struct evsel *evsel,
diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 0253184b3b58..6efa9d646637 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -1501,7 +1501,7 @@ static const struct evsel_str_handler contention_tracepoints[] = {
 	{ "lock:contention_end",   evsel__process_contention_end,   },
 };
 
-static int process_event_update(struct perf_tool *tool,
+static int process_event_update(const struct perf_tool *tool,
 				union perf_event *event,
 				struct evlist **pevlist)
 {
@@ -1520,7 +1520,7 @@ static int process_event_update(struct perf_tool *tool,
 typedef int (*tracepoint_handler)(struct evsel *evsel,
 				  struct perf_sample *sample);
 
-static int process_sample_event(struct perf_tool *tool __maybe_unused,
+static int process_sample_event(const struct perf_tool *tool __maybe_unused,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
diff --git a/tools/perf/builtin-mem.c b/tools/perf/builtin-mem.c
index efa700d14c98..0fb4d75ab959 100644
--- a/tools/perf/builtin-mem.c
+++ b/tools/perf/builtin-mem.c
@@ -179,7 +179,7 @@ out:
 }
 
 static int
-dump_raw_samples(struct perf_tool *tool,
+dump_raw_samples(const struct perf_tool *tool,
 		 union perf_event *event,
 		 struct perf_sample *sample,
 		 struct machine *machine)
@@ -253,7 +253,7 @@ out_put:
 	return 0;
 }
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel __maybe_unused,
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 72345d1e54b0..46410eb3a76b 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -609,7 +609,7 @@ static int record__comp_enabled(struct record *rec)
 	return rec->opts.comp_level > 0;
 }
 
-static int process_synthesized_event(struct perf_tool *tool,
+static int process_synthesized_event(const struct perf_tool *tool,
 				     union perf_event *event,
 				     struct perf_sample *sample __maybe_unused,
 				     struct machine *machine __maybe_unused)
@@ -620,7 +620,7 @@ static int process_synthesized_event(struct perf_tool *tool,
 
 static struct mutex synth_lock;
 
-static int process_locked_synthesized_event(struct perf_tool *tool,
+static int process_locked_synthesized_event(const struct perf_tool *tool,
 				     union perf_event *event,
 				     struct perf_sample *sample __maybe_unused,
 				     struct machine *machine __maybe_unused)
@@ -705,7 +705,7 @@ static void record__sig_exit(void)
 
 #ifdef HAVE_AUXTRACE_SUPPORT
 
-static int record__process_auxtrace(struct perf_tool *tool,
+static int record__process_auxtrace(const struct perf_tool *tool,
 				    struct mmap *map,
 				    union perf_event *event, void *data1,
 				    size_t len1, void *data2, size_t len2)
@@ -1417,7 +1417,7 @@ static void set_timestamp_boundary(struct record *rec, u64 sample_time)
 		rec->evlist->last_sample_time = sample_time;
 }
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
@@ -3244,7 +3244,7 @@ static const char * const __record_usage[] = {
 };
 const char * const *record_usage = __record_usage;
 
-static int build_id__process_mmap(struct perf_tool *tool, union perf_event *event,
+static int build_id__process_mmap(const struct perf_tool *tool, union perf_event *event,
 				  struct perf_sample *sample, struct machine *machine)
 {
 	/*
@@ -3256,7 +3256,7 @@ static int build_id__process_mmap(struct perf_tool *tool, union perf_event *even
 	return perf_event__process_mmap(tool, event, sample, machine);
 }
 
-static int build_id__process_mmap2(struct perf_tool *tool, union perf_event *event,
+static int build_id__process_mmap2(const struct perf_tool *tool, union perf_event *event,
 				   struct perf_sample *sample, struct machine *machine)
 {
 	/*
@@ -3269,7 +3269,7 @@ static int build_id__process_mmap2(struct perf_tool *tool, union perf_event *eve
 	return perf_event__process_mmap2(tool, event, sample, machine);
 }
 
-static int process_timestamp_boundary(struct perf_tool *tool,
+static int process_timestamp_boundary(const struct perf_tool *tool,
 				      union perf_event *event __maybe_unused,
 				      struct perf_sample *sample,
 				      struct machine *machine __maybe_unused)
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 930052961c1a..5f609a7791ea 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -263,7 +263,7 @@ static int process_feature_event(struct perf_session *session,
 	return 0;
 }
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
@@ -339,7 +339,7 @@ out_put:
 	return ret;
 }
 
-static int process_read_event(struct perf_tool *tool,
+static int process_read_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct evsel *evsel,
@@ -765,7 +765,7 @@ static void report__output_resort(struct report *rep)
 	ui_progress__finish();
 }
 
-static int count_sample_event(struct perf_tool *tool __maybe_unused,
+static int count_sample_event(const struct perf_tool *tool __maybe_unused,
 			      union perf_event *event __maybe_unused,
 			      struct perf_sample *sample __maybe_unused,
 			      struct evsel *evsel,
@@ -777,7 +777,7 @@ static int count_sample_event(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int count_lost_samples_event(struct perf_tool *tool,
+static int count_lost_samples_event(const struct perf_tool *tool,
 				    union perf_event *event,
 				    struct perf_sample *sample,
 				    struct machine *machine __maybe_unused)
@@ -793,7 +793,7 @@ static int count_lost_samples_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_attr(struct perf_tool *tool __maybe_unused,
+static int process_attr(const struct perf_tool *tool __maybe_unused,
 			union perf_event *event,
 			struct evlist **pevlist);
 
@@ -1233,7 +1233,7 @@ parse_percent_limit(const struct option *opt, const char *str,
 	return 0;
 }
 
-static int process_attr(struct perf_tool *tool __maybe_unused,
+static int process_attr(const struct perf_tool *tool __maybe_unused,
 			union perf_event *event,
 			struct evlist **pevlist)
 {
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 8750b5f2d49b..2c60bd3a8149 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1489,7 +1489,7 @@ again:
 	}
 }
 
-static int process_sched_wakeup_event(struct perf_tool *tool,
+static int process_sched_wakeup_event(const struct perf_tool *tool,
 				      struct evsel *evsel,
 				      struct perf_sample *sample,
 				      struct machine *machine)
@@ -1502,7 +1502,7 @@ static int process_sched_wakeup_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_sched_wakeup_ignore(struct perf_tool *tool __maybe_unused,
+static int process_sched_wakeup_ignore(const struct perf_tool *tool __maybe_unused,
 				      struct evsel *evsel __maybe_unused,
 				      struct perf_sample *sample __maybe_unused,
 				      struct machine *machine __maybe_unused)
@@ -1770,7 +1770,7 @@ out:
 	return 0;
 }
 
-static int process_sched_switch_event(struct perf_tool *tool,
+static int process_sched_switch_event(const struct perf_tool *tool,
 				      struct evsel *evsel,
 				      struct perf_sample *sample,
 				      struct machine *machine)
@@ -1796,7 +1796,7 @@ static int process_sched_switch_event(struct perf_tool *tool,
 	return err;
 }
 
-static int process_sched_runtime_event(struct perf_tool *tool,
+static int process_sched_runtime_event(const struct perf_tool *tool,
 				       struct evsel *evsel,
 				       struct perf_sample *sample,
 				       struct machine *machine)
@@ -1809,7 +1809,7 @@ static int process_sched_runtime_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int perf_sched__process_fork_event(struct perf_tool *tool,
+static int perf_sched__process_fork_event(const struct perf_tool *tool,
 					  union perf_event *event,
 					  struct perf_sample *sample,
 					  struct machine *machine)
@@ -1826,7 +1826,7 @@ static int perf_sched__process_fork_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_sched_migrate_task_event(struct perf_tool *tool,
+static int process_sched_migrate_task_event(const struct perf_tool *tool,
 					    struct evsel *evsel,
 					    struct perf_sample *sample,
 					    struct machine *machine)
@@ -1839,12 +1839,12 @@ static int process_sched_migrate_task_event(struct perf_tool *tool,
 	return 0;
 }
 
-typedef int (*tracepoint_handler)(struct perf_tool *tool,
+typedef int (*tracepoint_handler)(const struct perf_tool *tool,
 				  struct evsel *evsel,
 				  struct perf_sample *sample,
 				  struct machine *machine);
 
-static int perf_sched__process_tracepoint_sample(struct perf_tool *tool __maybe_unused,
+static int perf_sched__process_tracepoint_sample(const struct perf_tool *tool __maybe_unused,
 						 union perf_event *event __maybe_unused,
 						 struct perf_sample *sample,
 						 struct evsel *evsel,
@@ -1860,7 +1860,7 @@ static int perf_sched__process_tracepoint_sample(struct perf_tool *tool __maybe_
 	return err;
 }
 
-static int perf_sched__process_comm(struct perf_tool *tool __maybe_unused,
+static int perf_sched__process_comm(const struct perf_tool *tool __maybe_unused,
 				    union perf_event *event,
 				    struct perf_sample *sample,
 				    struct machine *machine)
@@ -2506,7 +2506,7 @@ static void timehist_print_wakeup_event(struct perf_sched *sched,
 	printf("\n");
 }
 
-static int timehist_sched_wakeup_ignore(struct perf_tool *tool __maybe_unused,
+static int timehist_sched_wakeup_ignore(const struct perf_tool *tool __maybe_unused,
 					union perf_event *event __maybe_unused,
 					struct evsel *evsel __maybe_unused,
 					struct perf_sample *sample __maybe_unused,
@@ -2515,7 +2515,7 @@ static int timehist_sched_wakeup_ignore(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int timehist_sched_wakeup_event(struct perf_tool *tool,
+static int timehist_sched_wakeup_event(const struct perf_tool *tool,
 				       union perf_event *event __maybe_unused,
 				       struct evsel *evsel,
 				       struct perf_sample *sample,
@@ -2599,7 +2599,7 @@ static void timehist_print_migration_event(struct perf_sched *sched,
 	printf("\n");
 }
 
-static int timehist_migrate_task_event(struct perf_tool *tool,
+static int timehist_migrate_task_event(const struct perf_tool *tool,
 				       union perf_event *event __maybe_unused,
 				       struct evsel *evsel,
 				       struct perf_sample *sample,
@@ -2627,7 +2627,7 @@ static int timehist_migrate_task_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int timehist_sched_change_event(struct perf_tool *tool,
+static int timehist_sched_change_event(const struct perf_tool *tool,
 				       union perf_event *event,
 				       struct evsel *evsel,
 				       struct perf_sample *sample,
@@ -2758,7 +2758,7 @@ out:
 	return rc;
 }
 
-static int timehist_sched_switch_event(struct perf_tool *tool,
+static int timehist_sched_switch_event(const struct perf_tool *tool,
 			     union perf_event *event,
 			     struct evsel *evsel,
 			     struct perf_sample *sample,
@@ -2767,7 +2767,7 @@ static int timehist_sched_switch_event(struct perf_tool *tool,
 	return timehist_sched_change_event(tool, event, evsel, sample, machine);
 }
 
-static int process_lost(struct perf_tool *tool __maybe_unused,
+static int process_lost(const struct perf_tool *tool __maybe_unused,
 			union perf_event *event,
 			struct perf_sample *sample,
 			struct machine *machine __maybe_unused)
@@ -3010,13 +3010,13 @@ static void timehist_print_summary(struct perf_sched *sched,
 	printf(" (x %d)\n", sched->max_cpu.cpu);
 }
 
-typedef int (*sched_handler)(struct perf_tool *tool,
+typedef int (*sched_handler)(const struct perf_tool *tool,
 			  union perf_event *event,
 			  struct evsel *evsel,
 			  struct perf_sample *sample,
 			  struct machine *machine);
 
-static int perf_timehist__process_sample(struct perf_tool *tool,
+static int perf_timehist__process_sample(const struct perf_tool *tool,
 					 union perf_event *event,
 					 struct perf_sample *sample,
 					 struct evsel *evsel,
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 932167b2362b..31a6f800d55f 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -2399,7 +2399,7 @@ static bool filter_cpu(struct perf_sample *sample)
 	return false;
 }
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
@@ -2486,7 +2486,7 @@ out_put:
 // Used when scr->per_event_dump is not set
 static struct evsel_script es_stdout;
 
-static int process_attr(struct perf_tool *tool, union perf_event *event,
+static int process_attr(const struct perf_tool *tool, union perf_event *event,
 			struct evlist **pevlist)
 {
 	struct perf_script *scr = container_of(tool, struct perf_script, tool);
@@ -2552,7 +2552,7 @@ static int process_attr(struct perf_tool *tool, union perf_event *event,
 	return 0;
 }
 
-static int print_event_with_time(struct perf_tool *tool,
+static int print_event_with_time(const struct perf_tool *tool,
 				 union perf_event *event,
 				 struct perf_sample *sample,
 				 struct machine *machine,
@@ -2588,14 +2588,14 @@ static int print_event_with_time(struct perf_tool *tool,
 	return 0;
 }
 
-static int print_event(struct perf_tool *tool, union perf_event *event,
+static int print_event(const struct perf_tool *tool, union perf_event *event,
 		       struct perf_sample *sample, struct machine *machine,
 		       pid_t pid, pid_t tid)
 {
 	return print_event_with_time(tool, event, sample, machine, pid, tid, 0);
 }
 
-static int process_comm_event(struct perf_tool *tool,
+static int process_comm_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample,
 			      struct machine *machine)
@@ -2607,7 +2607,7 @@ static int process_comm_event(struct perf_tool *tool,
 			   event->comm.tid);
 }
 
-static int process_namespaces_event(struct perf_tool *tool,
+static int process_namespaces_event(const struct perf_tool *tool,
 				    union perf_event *event,
 				    struct perf_sample *sample,
 				    struct machine *machine)
@@ -2619,7 +2619,7 @@ static int process_namespaces_event(struct perf_tool *tool,
 			   event->namespaces.tid);
 }
 
-static int process_cgroup_event(struct perf_tool *tool,
+static int process_cgroup_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct machine *machine)
@@ -2631,7 +2631,7 @@ static int process_cgroup_event(struct perf_tool *tool,
 			    sample->tid);
 }
 
-static int process_fork_event(struct perf_tool *tool,
+static int process_fork_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample,
 			      struct machine *machine)
@@ -2643,7 +2643,7 @@ static int process_fork_event(struct perf_tool *tool,
 				     event->fork.pid, event->fork.tid,
 				     event->fork.time);
 }
-static int process_exit_event(struct perf_tool *tool,
+static int process_exit_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample,
 			      struct machine *machine)
@@ -2656,7 +2656,7 @@ static int process_exit_event(struct perf_tool *tool,
 	return perf_event__process_exit(tool, event, sample, machine);
 }
 
-static int process_mmap_event(struct perf_tool *tool,
+static int process_mmap_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample,
 			      struct machine *machine)
@@ -2668,7 +2668,7 @@ static int process_mmap_event(struct perf_tool *tool,
 			   event->mmap.tid);
 }
 
-static int process_mmap2_event(struct perf_tool *tool,
+static int process_mmap2_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample,
 			      struct machine *machine)
@@ -2680,7 +2680,7 @@ static int process_mmap2_event(struct perf_tool *tool,
 			   event->mmap2.tid);
 }
 
-static int process_switch_event(struct perf_tool *tool,
+static int process_switch_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct machine *machine)
@@ -2712,7 +2712,7 @@ static int process_auxtrace_error(struct perf_session *session,
 }
 
 static int
-process_lost_event(struct perf_tool *tool,
+process_lost_event(const struct perf_tool *tool,
 		   union perf_event *event,
 		   struct perf_sample *sample,
 		   struct machine *machine)
@@ -2722,7 +2722,7 @@ process_lost_event(struct perf_tool *tool,
 }
 
 static int
-process_throttle_event(struct perf_tool *tool __maybe_unused,
+process_throttle_event(const struct perf_tool *tool __maybe_unused,
 		       union perf_event *event,
 		       struct perf_sample *sample,
 		       struct machine *machine)
@@ -2733,7 +2733,7 @@ process_throttle_event(struct perf_tool *tool __maybe_unused,
 }
 
 static int
-process_finished_round_event(struct perf_tool *tool __maybe_unused,
+process_finished_round_event(const struct perf_tool *tool __maybe_unused,
 			     union perf_event *event,
 			     struct ordered_events *oe __maybe_unused)
 
@@ -2743,7 +2743,7 @@ process_finished_round_event(struct perf_tool *tool __maybe_unused,
 }
 
 static int
-process_bpf_events(struct perf_tool *tool __maybe_unused,
+process_bpf_events(const struct perf_tool *tool __maybe_unused,
 		   union perf_event *event,
 		   struct perf_sample *sample,
 		   struct machine *machine)
@@ -2755,7 +2755,7 @@ process_bpf_events(struct perf_tool *tool __maybe_unused,
 			   sample->tid);
 }
 
-static int process_text_poke_events(struct perf_tool *tool,
+static int process_text_poke_events(const struct perf_tool *tool,
 				    union perf_event *event,
 				    struct perf_sample *sample,
 				    struct machine *machine)
@@ -3757,7 +3757,7 @@ static
 int process_thread_map_event(struct perf_session *session,
 			     union perf_event *event)
 {
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct perf_script *script = container_of(tool, struct perf_script, tool);
 
 	if (dump_trace)
@@ -3779,7 +3779,7 @@ static
 int process_cpu_map_event(struct perf_session *session,
 			  union perf_event *event)
 {
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct perf_script *script = container_of(tool, struct perf_script, tool);
 
 	if (dump_trace)
@@ -3809,11 +3809,10 @@ static int process_feature_event(struct perf_session *session,
 static int perf_script__process_auxtrace_info(struct perf_session *session,
 					      union perf_event *event)
 {
-	struct perf_tool *tool = session->tool;
-
 	int ret = perf_event__process_auxtrace_info(session, event);
 
 	if (ret == 0) {
+		const struct perf_tool *tool = session->tool;
 		struct perf_script *script = container_of(tool, struct perf_script, tool);
 
 		ret = perf_script__setup_per_event_dump(script);
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 1f92445f7480..d44e708f8a44 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -248,7 +248,7 @@ static void perf_stat__reset_stats(void)
 	perf_stat__reset_shadow_stats();
 }
 
-static int process_synthesized_event(struct perf_tool *tool __maybe_unused,
+static int process_synthesized_event(const struct perf_tool *tool __maybe_unused,
 				     union perf_event *event,
 				     struct perf_sample *sample __maybe_unused,
 				     struct machine *machine __maybe_unused)
@@ -2180,7 +2180,7 @@ static
 int process_stat_config_event(struct perf_session *session,
 			      union perf_event *event)
 {
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct perf_stat *st = container_of(tool, struct perf_stat, tool);
 
 	perf_event__read_stat_config(&stat_config, &event->stat_config);
@@ -2229,7 +2229,7 @@ static
 int process_thread_map_event(struct perf_session *session,
 			     union perf_event *event)
 {
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct perf_stat *st = container_of(tool, struct perf_stat, tool);
 
 	if (st->threads) {
@@ -2248,7 +2248,7 @@ static
 int process_cpu_map_event(struct perf_session *session,
 			  union perf_event *event)
 {
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct perf_stat *st = container_of(tool, struct perf_stat, tool);
 	struct perf_cpu_map *cpus;
 
diff --git a/tools/perf/builtin-timechart.c b/tools/perf/builtin-timechart.c
index 19d4542ea18a..5bf818baa662 100644
--- a/tools/perf/builtin-timechart.c
+++ b/tools/perf/builtin-timechart.c
@@ -320,7 +320,7 @@ static int *cpus_cstate_state;
 static u64 *cpus_pstate_start_times;
 static u64 *cpus_pstate_state;
 
-static int process_comm_event(struct perf_tool *tool,
+static int process_comm_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -330,7 +330,7 @@ static int process_comm_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_fork_event(struct perf_tool *tool,
+static int process_fork_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -340,7 +340,7 @@ static int process_fork_event(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_exit_event(struct perf_tool *tool,
+static int process_exit_event(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -571,7 +571,7 @@ typedef int (*tracepoint_handler)(struct timechart *tchart,
 				  struct perf_sample *sample,
 				  const char *backtrace);
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index d1a06a88d693..1cdac4e190e9 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -740,7 +740,7 @@ static int hist_iter__top_callback(struct hist_entry_iter *iter,
 	return 0;
 }
 
-static void perf_event__process_sample(struct perf_tool *tool,
+static void perf_event__process_sample(const struct perf_tool *tool,
 				       const union perf_event *event,
 				       struct evsel *evsel,
 				       struct perf_sample *sample,
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index ef951ce1a0dd..d6ca541fdc78 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1778,7 +1778,7 @@ static int trace__process_event(struct trace *trace, struct machine *machine,
 	return ret;
 }
 
-static int trace__tool_process(struct perf_tool *tool,
+static int trace__tool_process(const struct perf_tool *tool,
 			       union perf_event *event,
 			       struct perf_sample *sample,
 			       struct machine *machine)
@@ -3179,7 +3179,7 @@ static void trace__set_base_time(struct trace *trace,
 		trace->base_time = sample->time;
 }
 
-static int trace__process_sample(struct perf_tool *tool,
+static int trace__process_sample(const struct perf_tool *tool,
 				 union perf_event *event,
 				 struct perf_sample *sample,
 				 struct evsel *evsel,
diff --git a/tools/perf/tests/cpumap.c b/tools/perf/tests/cpumap.c
index bd8e396f3e57..2f0168b2a5a9 100644
--- a/tools/perf/tests/cpumap.c
+++ b/tools/perf/tests/cpumap.c
@@ -11,7 +11,7 @@
 
 struct machine;
 
-static int process_event_mask(struct perf_tool *tool __maybe_unused,
+static int process_event_mask(const struct perf_tool *tool __maybe_unused,
 			 union perf_event *event,
 			 struct perf_sample *sample __maybe_unused,
 			 struct machine *machine __maybe_unused)
@@ -47,7 +47,7 @@ static int process_event_mask(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int process_event_cpus(struct perf_tool *tool __maybe_unused,
+static int process_event_cpus(const struct perf_tool *tool __maybe_unused,
 			 union perf_event *event,
 			 struct perf_sample *sample __maybe_unused,
 			 struct machine *machine __maybe_unused)
@@ -73,7 +73,7 @@ static int process_event_cpus(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int process_event_range_cpus(struct perf_tool *tool __maybe_unused,
+static int process_event_range_cpus(const struct perf_tool *tool __maybe_unused,
 				union perf_event *event,
 				struct perf_sample *sample __maybe_unused,
 				struct machine *machine __maybe_unused)
diff --git a/tools/perf/tests/dlfilter-test.c b/tools/perf/tests/dlfilter-test.c
index da3a9b50b1b1..54f59d1246bc 100644
--- a/tools/perf/tests/dlfilter-test.c
+++ b/tools/perf/tests/dlfilter-test.c
@@ -62,7 +62,7 @@ static int test_result(const char *msg, int ret)
 	return ret;
 }
 
-static int process(struct perf_tool *tool, union perf_event *event,
+static int process(const struct perf_tool *tool, union perf_event *event,
 		   struct perf_sample *sample __maybe_unused,
 		   struct machine *machine __maybe_unused)
 {
diff --git a/tools/perf/tests/dwarf-unwind.c b/tools/perf/tests/dwarf-unwind.c
index d01aa931fe81..f85d391ced98 100644
--- a/tools/perf/tests/dwarf-unwind.c
+++ b/tools/perf/tests/dwarf-unwind.c
@@ -37,7 +37,7 @@
 #define NO_TAIL_CALL_BARRIER __asm__ __volatile__("" : : : "memory");
 #endif
 
-static int mmap_handler(struct perf_tool *tool __maybe_unused,
+static int mmap_handler(const struct perf_tool *tool __maybe_unused,
 			union perf_event *event,
 			struct perf_sample *sample,
 			struct machine *machine)
diff --git a/tools/perf/tests/event_update.c b/tools/perf/tests/event_update.c
index d093a9b878d1..fdecad920f59 100644
--- a/tools/perf/tests/event_update.c
+++ b/tools/perf/tests/event_update.c
@@ -12,7 +12,7 @@
 #include "tests.h"
 #include "debug.h"
 
-static int process_event_unit(struct perf_tool *tool __maybe_unused,
+static int process_event_unit(const struct perf_tool *tool __maybe_unused,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -25,7 +25,7 @@ static int process_event_unit(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int process_event_scale(struct perf_tool *tool __maybe_unused,
+static int process_event_scale(const struct perf_tool *tool __maybe_unused,
 			       union perf_event *event,
 			       struct perf_sample *sample __maybe_unused,
 			       struct machine *machine __maybe_unused)
@@ -43,7 +43,7 @@ struct event_name {
 	const char *name;
 };
 
-static int process_event_name(struct perf_tool *tool,
+static int process_event_name(const struct perf_tool *tool,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -57,7 +57,7 @@ static int process_event_name(struct perf_tool *tool,
 	return 0;
 }
 
-static int process_event_cpus(struct perf_tool *tool __maybe_unused,
+static int process_event_cpus(const struct perf_tool *tool __maybe_unused,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
diff --git a/tools/perf/tests/stat.c b/tools/perf/tests/stat.c
index 706780fb5695..6468cc0d0204 100644
--- a/tools/perf/tests/stat.c
+++ b/tools/perf/tests/stat.c
@@ -21,7 +21,7 @@ static bool has_term(struct perf_record_stat_config *config,
 	return false;
 }
 
-static int process_stat_config_event(struct perf_tool *tool __maybe_unused,
+static int process_stat_config_event(const struct perf_tool *tool __maybe_unused,
 				     union perf_event *event,
 				     struct perf_sample *sample __maybe_unused,
 				     struct machine *machine __maybe_unused)
@@ -62,7 +62,7 @@ static int test__synthesize_stat_config(struct test_suite *test __maybe_unused,
 	return 0;
 }
 
-static int process_stat_event(struct perf_tool *tool __maybe_unused,
+static int process_stat_event(const struct perf_tool *tool __maybe_unused,
 			      union perf_event *event,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -93,7 +93,7 @@ static int test__synthesize_stat(struct test_suite *test __maybe_unused, int sub
 	return 0;
 }
 
-static int process_stat_round_event(struct perf_tool *tool __maybe_unused,
+static int process_stat_round_event(const struct perf_tool *tool __maybe_unused,
 				    union perf_event *event,
 				    struct perf_sample *sample __maybe_unused,
 				    struct machine *machine __maybe_unused)
diff --git a/tools/perf/tests/thread-map.c b/tools/perf/tests/thread-map.c
index 74308c1368fe..1fe521466bf4 100644
--- a/tools/perf/tests/thread-map.c
+++ b/tools/perf/tests/thread-map.c
@@ -60,7 +60,7 @@ static int test__thread_map(struct test_suite *test __maybe_unused, int subtest
 	return 0;
 }
 
-static int process_event(struct perf_tool *tool __maybe_unused,
+static int process_event(const struct perf_tool *tool __maybe_unused,
 			 union perf_event *event,
 			 struct perf_sample *sample __maybe_unused,
 			 struct machine *machine __maybe_unused)
diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index fa40f3cb6266..138ffc71b32d 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -899,7 +899,7 @@ static int arm_spe_context_switch(struct arm_spe *spe, union perf_event *event,
 static int arm_spe_process_event(struct perf_session *session,
 				 union perf_event *event,
 				 struct perf_sample *sample,
-				 struct perf_tool *tool)
+				 const struct perf_tool *tool)
 {
 	int err = 0;
 	u64 timestamp;
@@ -947,7 +947,7 @@ static int arm_spe_process_event(struct perf_session *session,
 
 static int arm_spe_process_auxtrace_event(struct perf_session *session,
 					  union perf_event *event,
-					  struct perf_tool *tool __maybe_unused)
+					  const struct perf_tool *tool __maybe_unused)
 {
 	struct arm_spe *spe = container_of(session->auxtrace, struct arm_spe,
 					     auxtrace);
@@ -985,7 +985,7 @@ static int arm_spe_process_auxtrace_event(struct perf_session *session,
 }
 
 static int arm_spe_flush(struct perf_session *session __maybe_unused,
-			 struct perf_tool *tool __maybe_unused)
+			 const struct perf_tool *tool __maybe_unused)
 {
 	struct arm_spe *spe = container_of(session->auxtrace, struct arm_spe,
 			auxtrace);
diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index e2f317063eec..cbb773ed6f1a 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -1240,7 +1240,7 @@ void auxtrace_synth_error(struct perf_record_auxtrace_error *auxtrace_error, int
 }
 
 int perf_event__synthesize_auxtrace_info(struct auxtrace_record *itr,
-					 struct perf_tool *tool,
+					 const struct perf_tool *tool,
 					 struct perf_session *session,
 					 perf_event__handler_t process)
 {
@@ -1831,7 +1831,7 @@ int __weak compat_auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
 
 static int __auxtrace_mmap__read(struct mmap *map,
 				 struct auxtrace_record *itr,
-				 struct perf_tool *tool, process_auxtrace_t fn,
+				 const struct perf_tool *tool, process_auxtrace_t fn,
 				 bool snapshot, size_t snapshot_size)
 {
 	struct auxtrace_mmap *mm = &map->auxtrace_mmap;
@@ -1942,14 +1942,14 @@ static int __auxtrace_mmap__read(struct mmap *map,
 }
 
 int auxtrace_mmap__read(struct mmap *map, struct auxtrace_record *itr,
-			struct perf_tool *tool, process_auxtrace_t fn)
+			const struct perf_tool *tool, process_auxtrace_t fn)
 {
 	return __auxtrace_mmap__read(map, itr, tool, fn, false, 0);
 }
 
 int auxtrace_mmap__read_snapshot(struct mmap *map,
 				 struct auxtrace_record *itr,
-				 struct perf_tool *tool, process_auxtrace_t fn,
+				 const struct perf_tool *tool, process_auxtrace_t fn,
 				 size_t snapshot_size)
 {
 	return __auxtrace_mmap__read(map, itr, tool, fn, true, snapshot_size);
@@ -2829,7 +2829,7 @@ int auxtrace_parse_filters(struct evlist *evlist)
 }
 
 int auxtrace__process_event(struct perf_session *session, union perf_event *event,
-			    struct perf_sample *sample, struct perf_tool *tool)
+			    struct perf_sample *sample, const struct perf_tool *tool)
 {
 	if (!session->auxtrace)
 		return 0;
@@ -2847,7 +2847,7 @@ void auxtrace__dump_auxtrace_sample(struct perf_session *session,
 	session->auxtrace->dump_auxtrace_sample(session, sample);
 }
 
-int auxtrace__flush_events(struct perf_session *session, struct perf_tool *tool)
+int auxtrace__flush_events(struct perf_session *session, const struct perf_tool *tool)
 {
 	if (!session->auxtrace)
 		return 0;
diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index 8a6ec9565835..d405efcd8708 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -208,17 +208,17 @@ struct auxtrace {
 	int (*process_event)(struct perf_session *session,
 			     union perf_event *event,
 			     struct perf_sample *sample,
-			     struct perf_tool *tool);
+			     const struct perf_tool *tool);
 	int (*process_auxtrace_event)(struct perf_session *session,
 				      union perf_event *event,
-				      struct perf_tool *tool);
+				      const struct perf_tool *tool);
 	int (*queue_data)(struct perf_session *session,
 			  struct perf_sample *sample, union perf_event *event,
 			  u64 data_offset);
 	void (*dump_auxtrace_sample)(struct perf_session *session,
 				     struct perf_sample *sample);
 	int (*flush_events)(struct perf_session *session,
-			    struct perf_tool *tool);
+			    const struct perf_tool *tool);
 	void (*free_events)(struct perf_session *session);
 	void (*free)(struct perf_session *session);
 	bool (*evsel_is_auxtrace)(struct perf_session *session,
@@ -508,17 +508,17 @@ void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
 				   struct evlist *evlist,
 				   struct evsel *evsel, int idx);
 
-typedef int (*process_auxtrace_t)(struct perf_tool *tool,
+typedef int (*process_auxtrace_t)(const struct perf_tool *tool,
 				  struct mmap *map,
 				  union perf_event *event, void *data1,
 				  size_t len1, void *data2, size_t len2);
 
 int auxtrace_mmap__read(struct mmap *map, struct auxtrace_record *itr,
-			struct perf_tool *tool, process_auxtrace_t fn);
+			const struct perf_tool *tool, process_auxtrace_t fn);
 
 int auxtrace_mmap__read_snapshot(struct mmap *map,
 				 struct auxtrace_record *itr,
-				 struct perf_tool *tool, process_auxtrace_t fn,
+				 const struct perf_tool *tool, process_auxtrace_t fn,
 				 size_t snapshot_size);
 
 int auxtrace_queues__init_nr(struct auxtrace_queues *queues, int nr_queues);
@@ -639,10 +639,10 @@ int addr_filters__parse_bare_filter(struct addr_filters *filts,
 int auxtrace_parse_filters(struct evlist *evlist);
 
 int auxtrace__process_event(struct perf_session *session, union perf_event *event,
-			    struct perf_sample *sample, struct perf_tool *tool);
+			    struct perf_sample *sample, const struct perf_tool *tool);
 void auxtrace__dump_auxtrace_sample(struct perf_session *session,
 				    struct perf_sample *sample);
-int auxtrace__flush_events(struct perf_session *session, struct perf_tool *tool);
+int auxtrace__flush_events(struct perf_session *session, const struct perf_tool *tool);
 void auxtrace__free_events(struct perf_session *session);
 void auxtrace__free(struct perf_session *session);
 bool auxtrace__evsel_is_auxtrace(struct perf_session *session,
@@ -809,7 +809,7 @@ static inline
 int auxtrace__process_event(struct perf_session *session __maybe_unused,
 			    union perf_event *event __maybe_unused,
 			    struct perf_sample *sample __maybe_unused,
-			    struct perf_tool *tool __maybe_unused)
+			    const struct perf_tool *tool __maybe_unused)
 {
 	return 0;
 }
@@ -822,7 +822,7 @@ void auxtrace__dump_auxtrace_sample(struct perf_session *session __maybe_unused,
 
 static inline
 int auxtrace__flush_events(struct perf_session *session __maybe_unused,
-			   struct perf_tool *tool __maybe_unused)
+			   const struct perf_tool *tool __maybe_unused)
 {
 	return 0;
 }
diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c
index 827695cd0408..13608237c50e 100644
--- a/tools/perf/util/bpf-event.c
+++ b/tools/perf/util/bpf-event.c
@@ -170,7 +170,7 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session,
 {
 	struct perf_record_ksymbol *ksymbol_event = &event->ksymbol;
 	struct perf_record_bpf_event *bpf_event = &event->bpf;
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct bpf_prog_info_node *info_node;
 	struct perf_bpil *info_linear;
 	struct bpf_prog_info *info;
@@ -310,7 +310,7 @@ struct kallsyms_parse {
 	union perf_event	*event;
 	perf_event__handler_t	 process;
 	struct machine		*machine;
-	struct perf_tool	*tool;
+	const struct perf_tool	*tool;
 };
 
 static int
diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 83a1581e8cf1..098fcc625d91 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -42,7 +42,7 @@
 
 static bool no_buildid_cache;
 
-int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
+int build_id__mark_dso_hit(const struct perf_tool *tool __maybe_unused,
 			   union perf_event *event,
 			   struct perf_sample *sample,
 			   struct evsel *evsel __maybe_unused,
@@ -67,7 +67,7 @@ int build_id__mark_dso_hit(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int perf_event__exit_del_thread(struct perf_tool *tool __maybe_unused,
+static int perf_event__exit_del_thread(const struct perf_tool *tool __maybe_unused,
 				       union perf_event *event,
 				       struct perf_sample *sample
 				       __maybe_unused,
diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
index 3fa8bffb07ca..ae87c4c58d5b 100644
--- a/tools/perf/util/build-id.h
+++ b/tools/perf/util/build-id.h
@@ -35,11 +35,11 @@ char *dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
 char *__dso__build_id_filename(const struct dso *dso, char *bf, size_t size,
 			       bool is_debug, bool is_kallsyms);
 
-int build_id__mark_dso_hit(struct perf_tool *tool, union perf_event *event,
+int build_id__mark_dso_hit(const struct perf_tool *tool, union perf_event *event,
 			   struct perf_sample *sample, struct evsel *evsel,
 			   struct machine *machine);
 
-int perf_event__inject_buildid(struct perf_tool *tool, union perf_event *event,
+int perf_event__inject_buildid(const struct perf_tool *tool, union perf_event *event,
 			       struct perf_sample *sample, struct evsel *evsel,
 			       struct machine *machine);
 
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index 566498ebc694..34552940ec1d 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -788,7 +788,7 @@ static void cs_etm__dump_event(struct cs_etm_queue *etmq,
 }
 
 static int cs_etm__flush_events(struct perf_session *session,
-				struct perf_tool *tool)
+				const struct perf_tool *tool)
 {
 	struct cs_etm_auxtrace *etm = container_of(session->auxtrace,
 						   struct cs_etm_auxtrace,
@@ -2715,7 +2715,7 @@ static int cs_etm__process_switch_cpu_wide(struct cs_etm_auxtrace *etm,
 static int cs_etm__process_event(struct perf_session *session,
 				 union perf_event *event,
 				 struct perf_sample *sample,
-				 struct perf_tool *tool)
+				 const struct perf_tool *tool)
 {
 	struct cs_etm_auxtrace *etm = container_of(session->auxtrace,
 						   struct cs_etm_auxtrace,
@@ -2785,7 +2785,7 @@ static void dump_queued_data(struct cs_etm_auxtrace *etm,
 
 static int cs_etm__process_auxtrace_event(struct perf_session *session,
 					  union perf_event *event,
-					  struct perf_tool *tool __maybe_unused)
+					  const struct perf_tool *tool __maybe_unused)
 {
 	struct cs_etm_auxtrace *etm = container_of(session->auxtrace,
 						   struct cs_etm_auxtrace,
diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
index 2b732bccabad..9e2170604b66 100644
--- a/tools/perf/util/data-convert-bt.c
+++ b/tools/perf/util/data-convert-bt.c
@@ -792,7 +792,7 @@ static bool is_flush_needed(struct ctf_stream *cs)
 	return cs->count >= STREAM_FLUSH_COUNT;
 }
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *_event,
 				struct perf_sample *sample,
 				struct evsel *evsel,
@@ -871,7 +871,7 @@ do {							\
 } while(0)
 
 #define __FUNC_PROCESS_NON_SAMPLE(_name, body) 	\
-static int process_##_name##_event(struct perf_tool *tool,	\
+static int process_##_name##_event(const struct perf_tool *tool,	\
 				   union perf_event *_event,	\
 				   struct perf_sample *sample,	\
 				   struct machine *machine)	\
diff --git a/tools/perf/util/data-convert-json.c b/tools/perf/util/data-convert-json.c
index 3cf64f5b23ee..905ea9823f9d 100644
--- a/tools/perf/util/data-convert-json.c
+++ b/tools/perf/util/data-convert-json.c
@@ -118,7 +118,7 @@ static void output_json_key_format(FILE *out, bool comma, int depth,
 	va_end(args);
 }
 
-static void output_sample_callchain_entry(struct perf_tool *tool,
+static void output_sample_callchain_entry(const struct perf_tool *tool,
 		u64 ip, struct addr_location *al)
 {
 	struct convert_json *c = container_of(tool, struct convert_json, tool);
@@ -146,7 +146,7 @@ static void output_sample_callchain_entry(struct perf_tool *tool,
 	output_json_format(out, false, 4, "}");
 }
 
-static int process_sample_event(struct perf_tool *tool,
+static int process_sample_event(const struct perf_tool *tool,
 				union perf_event *event __maybe_unused,
 				struct perf_sample *sample,
 				struct evsel *evsel __maybe_unused,
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index f32f9abf6344..c2f0e7f40ad5 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -216,7 +216,7 @@ size_t perf_event__fprintf_cgroup(union perf_event *event, FILE *fp)
 		       event->cgroup.id, event->cgroup.path);
 }
 
-int perf_event__process_comm(struct perf_tool *tool __maybe_unused,
+int perf_event__process_comm(const struct perf_tool *tool __maybe_unused,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine)
@@ -224,7 +224,7 @@ int perf_event__process_comm(struct perf_tool *tool __maybe_unused,
 	return machine__process_comm_event(machine, event, sample);
 }
 
-int perf_event__process_namespaces(struct perf_tool *tool __maybe_unused,
+int perf_event__process_namespaces(const struct perf_tool *tool __maybe_unused,
 				   union perf_event *event,
 				   struct perf_sample *sample,
 				   struct machine *machine)
@@ -232,7 +232,7 @@ int perf_event__process_namespaces(struct perf_tool *tool __maybe_unused,
 	return machine__process_namespaces_event(machine, event, sample);
 }
 
-int perf_event__process_cgroup(struct perf_tool *tool __maybe_unused,
+int perf_event__process_cgroup(const struct perf_tool *tool __maybe_unused,
 			       union perf_event *event,
 			       struct perf_sample *sample,
 			       struct machine *machine)
@@ -240,7 +240,7 @@ int perf_event__process_cgroup(struct perf_tool *tool __maybe_unused,
 	return machine__process_cgroup_event(machine, event, sample);
 }
 
-int perf_event__process_lost(struct perf_tool *tool __maybe_unused,
+int perf_event__process_lost(const struct perf_tool *tool __maybe_unused,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine)
@@ -248,7 +248,7 @@ int perf_event__process_lost(struct perf_tool *tool __maybe_unused,
 	return machine__process_lost_event(machine, event, sample);
 }
 
-int perf_event__process_aux(struct perf_tool *tool __maybe_unused,
+int perf_event__process_aux(const struct perf_tool *tool __maybe_unused,
 			    union perf_event *event,
 			    struct perf_sample *sample __maybe_unused,
 			    struct machine *machine)
@@ -256,7 +256,7 @@ int perf_event__process_aux(struct perf_tool *tool __maybe_unused,
 	return machine__process_aux_event(machine, event);
 }
 
-int perf_event__process_itrace_start(struct perf_tool *tool __maybe_unused,
+int perf_event__process_itrace_start(const struct perf_tool *tool __maybe_unused,
 				     union perf_event *event,
 				     struct perf_sample *sample __maybe_unused,
 				     struct machine *machine)
@@ -264,7 +264,7 @@ int perf_event__process_itrace_start(struct perf_tool *tool __maybe_unused,
 	return machine__process_itrace_start_event(machine, event);
 }
 
-int perf_event__process_aux_output_hw_id(struct perf_tool *tool __maybe_unused,
+int perf_event__process_aux_output_hw_id(const struct perf_tool *tool __maybe_unused,
 					 union perf_event *event,
 					 struct perf_sample *sample __maybe_unused,
 					 struct machine *machine)
@@ -272,7 +272,7 @@ int perf_event__process_aux_output_hw_id(struct perf_tool *tool __maybe_unused,
 	return machine__process_aux_output_hw_id_event(machine, event);
 }
 
-int perf_event__process_lost_samples(struct perf_tool *tool __maybe_unused,
+int perf_event__process_lost_samples(const struct perf_tool *tool __maybe_unused,
 				     union perf_event *event,
 				     struct perf_sample *sample,
 				     struct machine *machine)
@@ -280,7 +280,7 @@ int perf_event__process_lost_samples(struct perf_tool *tool __maybe_unused,
 	return machine__process_lost_samples_event(machine, event, sample);
 }
 
-int perf_event__process_switch(struct perf_tool *tool __maybe_unused,
+int perf_event__process_switch(const struct perf_tool *tool __maybe_unused,
 			       union perf_event *event,
 			       struct perf_sample *sample __maybe_unused,
 			       struct machine *machine)
@@ -288,7 +288,7 @@ int perf_event__process_switch(struct perf_tool *tool __maybe_unused,
 	return machine__process_switch_event(machine, event);
 }
 
-int perf_event__process_ksymbol(struct perf_tool *tool __maybe_unused,
+int perf_event__process_ksymbol(const struct perf_tool *tool __maybe_unused,
 				union perf_event *event,
 				struct perf_sample *sample __maybe_unused,
 				struct machine *machine)
@@ -296,7 +296,7 @@ int perf_event__process_ksymbol(struct perf_tool *tool __maybe_unused,
 	return machine__process_ksymbol(machine, event, sample);
 }
 
-int perf_event__process_bpf(struct perf_tool *tool __maybe_unused,
+int perf_event__process_bpf(const struct perf_tool *tool __maybe_unused,
 			    union perf_event *event,
 			    struct perf_sample *sample,
 			    struct machine *machine)
@@ -304,7 +304,7 @@ int perf_event__process_bpf(struct perf_tool *tool __maybe_unused,
 	return machine__process_bpf(machine, event, sample);
 }
 
-int perf_event__process_text_poke(struct perf_tool *tool __maybe_unused,
+int perf_event__process_text_poke(const struct perf_tool *tool __maybe_unused,
 				  union perf_event *event,
 				  struct perf_sample *sample,
 				  struct machine *machine)
@@ -387,7 +387,7 @@ size_t perf_event__fprintf_cpu_map(union perf_event *event, FILE *fp)
 	return ret;
 }
 
-int perf_event__process_mmap(struct perf_tool *tool __maybe_unused,
+int perf_event__process_mmap(const struct perf_tool *tool __maybe_unused,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine)
@@ -395,7 +395,7 @@ int perf_event__process_mmap(struct perf_tool *tool __maybe_unused,
 	return machine__process_mmap_event(machine, event, sample);
 }
 
-int perf_event__process_mmap2(struct perf_tool *tool __maybe_unused,
+int perf_event__process_mmap2(const struct perf_tool *tool __maybe_unused,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine)
@@ -410,7 +410,7 @@ size_t perf_event__fprintf_task(union perf_event *event, FILE *fp)
 		       event->fork.ppid, event->fork.ptid);
 }
 
-int perf_event__process_fork(struct perf_tool *tool __maybe_unused,
+int perf_event__process_fork(const struct perf_tool *tool __maybe_unused,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine)
@@ -418,7 +418,7 @@ int perf_event__process_fork(struct perf_tool *tool __maybe_unused,
 	return machine__process_fork_event(machine, event, sample);
 }
 
-int perf_event__process_exit(struct perf_tool *tool __maybe_unused,
+int perf_event__process_exit(const struct perf_tool *tool __maybe_unused,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine)
@@ -587,7 +587,7 @@ size_t perf_event__fprintf(union perf_event *event, struct machine *machine, FIL
 	return ret;
 }
 
-int perf_event__process(struct perf_tool *tool __maybe_unused,
+int perf_event__process(const struct perf_tool *tool __maybe_unused,
 			union perf_event *event,
 			struct perf_sample *sample,
 			struct machine *machine)
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index d8bcee2e9b93..4b24f1c580fd 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -267,71 +267,71 @@ struct perf_tool;
 void perf_event__read_stat_config(struct perf_stat_config *config,
 				  struct perf_record_stat_config *event);
 
-int perf_event__process_comm(struct perf_tool *tool,
+int perf_event__process_comm(const struct perf_tool *tool,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine);
-int perf_event__process_lost(struct perf_tool *tool,
+int perf_event__process_lost(const struct perf_tool *tool,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine);
-int perf_event__process_lost_samples(struct perf_tool *tool,
+int perf_event__process_lost_samples(const struct perf_tool *tool,
 				     union perf_event *event,
 				     struct perf_sample *sample,
 				     struct machine *machine);
-int perf_event__process_aux(struct perf_tool *tool,
+int perf_event__process_aux(const struct perf_tool *tool,
 			    union perf_event *event,
 			    struct perf_sample *sample,
 			    struct machine *machine);
-int perf_event__process_itrace_start(struct perf_tool *tool,
+int perf_event__process_itrace_start(const struct perf_tool *tool,
 				     union perf_event *event,
 				     struct perf_sample *sample,
 				     struct machine *machine);
-int perf_event__process_aux_output_hw_id(struct perf_tool *tool,
+int perf_event__process_aux_output_hw_id(const struct perf_tool *tool,
 					 union perf_event *event,
 					 struct perf_sample *sample,
 					 struct machine *machine);
-int perf_event__process_switch(struct perf_tool *tool,
+int perf_event__process_switch(const struct perf_tool *tool,
 			       union perf_event *event,
 			       struct perf_sample *sample,
 			       struct machine *machine);
-int perf_event__process_namespaces(struct perf_tool *tool,
+int perf_event__process_namespaces(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct perf_sample *sample,
 				   struct machine *machine);
-int perf_event__process_cgroup(struct perf_tool *tool,
+int perf_event__process_cgroup(const struct perf_tool *tool,
 			       union perf_event *event,
 			       struct perf_sample *sample,
 			       struct machine *machine);
-int perf_event__process_mmap(struct perf_tool *tool,
+int perf_event__process_mmap(const struct perf_tool *tool,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine);
-int perf_event__process_mmap2(struct perf_tool *tool,
+int perf_event__process_mmap2(const struct perf_tool *tool,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine);
-int perf_event__process_fork(struct perf_tool *tool,
+int perf_event__process_fork(const struct perf_tool *tool,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine);
-int perf_event__process_exit(struct perf_tool *tool,
+int perf_event__process_exit(const struct perf_tool *tool,
 			     union perf_event *event,
 			     struct perf_sample *sample,
 			     struct machine *machine);
-int perf_event__process_ksymbol(struct perf_tool *tool,
+int perf_event__process_ksymbol(const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct machine *machine);
-int perf_event__process_bpf(struct perf_tool *tool,
+int perf_event__process_bpf(const struct perf_tool *tool,
 			    union perf_event *event,
 			    struct perf_sample *sample,
 			    struct machine *machine);
-int perf_event__process_text_poke(struct perf_tool *tool,
+int perf_event__process_text_poke(const struct perf_tool *tool,
 				  union perf_event *event,
 				  struct perf_sample *sample,
 				  struct machine *machine);
-int perf_event__process(struct perf_tool *tool,
+int perf_event__process(const struct perf_tool *tool,
 			union perf_event *event,
 			struct perf_sample *sample,
 			struct machine *machine);
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 55e9553861d0..3309fe7f1d12 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -4326,7 +4326,7 @@ out_delete_evlist:
 int perf_event__process_feature(struct perf_session *session,
 				union perf_event *event)
 {
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct feat_fd ff = { .fd = 0 };
 	struct perf_record_header_feature *fe = (struct perf_record_header_feature *)event;
 	int type = fe->header.type;
@@ -4405,7 +4405,7 @@ size_t perf_event__fprintf_event_update(union perf_event *event, FILE *fp)
 	return ret;
 }
 
-int perf_event__process_attr(struct perf_tool *tool __maybe_unused,
+int perf_event__process_attr(const struct perf_tool *tool __maybe_unused,
 			     union perf_event *event,
 			     struct evlist **pevlist)
 {
@@ -4444,7 +4444,7 @@ int perf_event__process_attr(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-int perf_event__process_event_update(struct perf_tool *tool __maybe_unused,
+int perf_event__process_event_update(const struct perf_tool *tool __maybe_unused,
 				     union perf_event *event,
 				     struct evlist **pevlist)
 {
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 7c16a250e738..07ff647197ff 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -156,9 +156,9 @@ int perf_header__fprintf_info(struct perf_session *s, FILE *fp, bool full);
 
 int perf_event__process_feature(struct perf_session *session,
 				union perf_event *event);
-int perf_event__process_attr(struct perf_tool *tool, union perf_event *event,
+int perf_event__process_attr(const struct perf_tool *tool, union perf_event *event,
 			     struct evlist **pevlist);
-int perf_event__process_event_update(struct perf_tool *tool,
+int perf_event__process_event_update(const struct perf_tool *tool,
 				     union perf_event *event,
 				     struct evlist **pevlist);
 size_t perf_event__fprintf_event_update(union perf_event *event, FILE *fp);
diff --git a/tools/perf/util/hisi-ptt.c b/tools/perf/util/hisi-ptt.c
index 37ea987017f6..e4cc4785f744 100644
--- a/tools/perf/util/hisi-ptt.c
+++ b/tools/perf/util/hisi-ptt.c
@@ -79,14 +79,14 @@ static void hisi_ptt_dump_event(struct hisi_ptt *ptt, unsigned char *buf,
 static int hisi_ptt_process_event(struct perf_session *session __maybe_unused,
 				  union perf_event *event __maybe_unused,
 				  struct perf_sample *sample __maybe_unused,
-				  struct perf_tool *tool __maybe_unused)
+				  const struct perf_tool *tool __maybe_unused)
 {
 	return 0;
 }
 
 static int hisi_ptt_process_auxtrace_event(struct perf_session *session,
 					   union perf_event *event,
-					   struct perf_tool *tool __maybe_unused)
+					   const struct perf_tool *tool __maybe_unused)
 {
 	struct hisi_ptt *ptt = container_of(session->auxtrace, struct hisi_ptt,
 					    auxtrace);
@@ -123,7 +123,7 @@ static int hisi_ptt_process_auxtrace_event(struct perf_session *session,
 }
 
 static int hisi_ptt_flush(struct perf_session *session __maybe_unused,
-			  struct perf_tool *tool __maybe_unused)
+			  const struct perf_tool *tool __maybe_unused)
 {
 	return 0;
 }
diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
index 160d346cb450..27d9b5c9fec8 100644
--- a/tools/perf/util/intel-bts.c
+++ b/tools/perf/util/intel-bts.c
@@ -591,7 +591,7 @@ static int intel_bts_process_queues(struct intel_bts *bts, u64 timestamp)
 static int intel_bts_process_event(struct perf_session *session,
 				   union perf_event *event,
 				   struct perf_sample *sample,
-				   struct perf_tool *tool)
+				   const struct perf_tool *tool)
 {
 	struct intel_bts *bts = container_of(session->auxtrace, struct intel_bts,
 					     auxtrace);
@@ -634,7 +634,7 @@ static int intel_bts_process_event(struct perf_session *session,
 
 static int intel_bts_process_auxtrace_event(struct perf_session *session,
 					    union perf_event *event,
-					    struct perf_tool *tool __maybe_unused)
+					    const struct perf_tool *tool __maybe_unused)
 {
 	struct intel_bts *bts = container_of(session->auxtrace, struct intel_bts,
 					     auxtrace);
@@ -675,7 +675,7 @@ static int intel_bts_process_auxtrace_event(struct perf_session *session,
 }
 
 static int intel_bts_flush(struct perf_session *session,
-			   struct perf_tool *tool __maybe_unused)
+			   const struct perf_tool *tool __maybe_unused)
 {
 	struct intel_bts *bts = container_of(session->auxtrace, struct intel_bts,
 					     auxtrace);
diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
index 1fc03bfd14c3..fd2597613f3d 100644
--- a/tools/perf/util/intel-pt.c
+++ b/tools/perf/util/intel-pt.c
@@ -3449,7 +3449,7 @@ out:
 static int intel_pt_process_event(struct perf_session *session,
 				  union perf_event *event,
 				  struct perf_sample *sample,
-				  struct perf_tool *tool)
+				  const struct perf_tool *tool)
 {
 	struct intel_pt *pt = container_of(session->auxtrace, struct intel_pt,
 					   auxtrace);
@@ -3533,7 +3533,7 @@ static int intel_pt_process_event(struct perf_session *session,
 	return err;
 }
 
-static int intel_pt_flush(struct perf_session *session, struct perf_tool *tool)
+static int intel_pt_flush(struct perf_session *session, const struct perf_tool *tool)
 {
 	struct intel_pt *pt = container_of(session->auxtrace, struct intel_pt,
 					   auxtrace);
@@ -3600,7 +3600,7 @@ static bool intel_pt_evsel_is_auxtrace(struct perf_session *session,
 
 static int intel_pt_process_auxtrace_event(struct perf_session *session,
 					   union perf_event *event,
-					   struct perf_tool *tool __maybe_unused)
+					   const struct perf_tool *tool __maybe_unused)
 {
 	struct intel_pt *pt = container_of(session->auxtrace, struct intel_pt,
 					   auxtrace);
diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
index 1f657ef8975f..5ce13653512b 100644
--- a/tools/perf/util/jitdump.c
+++ b/tools/perf/util/jitdump.c
@@ -424,7 +424,7 @@ static int jit_repipe_code_load(struct jit_buf_desc *jd, union jr_entry *jr)
 {
 	struct perf_sample sample;
 	union perf_event *event;
-	struct perf_tool *tool = jd->session->tool;
+	const struct perf_tool *tool = jd->session->tool;
 	uint64_t code, addr;
 	uintptr_t uaddr;
 	char *filename;
@@ -543,7 +543,7 @@ static int jit_repipe_code_move(struct jit_buf_desc *jd, union jr_entry *jr)
 {
 	struct perf_sample sample;
 	union perf_event *event;
-	struct perf_tool *tool = jd->session->tool;
+	const struct perf_tool *tool = jd->session->tool;
 	char *filename;
 	size_t size;
 	struct stat st;
diff --git a/tools/perf/util/s390-cpumsf.c b/tools/perf/util/s390-cpumsf.c
index 4ec583e511af..73846b73d0cf 100644
--- a/tools/perf/util/s390-cpumsf.c
+++ b/tools/perf/util/s390-cpumsf.c
@@ -912,7 +912,7 @@ static int
 s390_cpumsf_process_event(struct perf_session *session,
 			  union perf_event *event,
 			  struct perf_sample *sample,
-			  struct perf_tool *tool)
+			  const struct perf_tool *tool)
 {
 	struct s390_cpumsf *sf = container_of(session->auxtrace,
 					      struct s390_cpumsf,
@@ -955,7 +955,7 @@ s390_cpumsf_process_event(struct perf_session *session,
 static int
 s390_cpumsf_process_auxtrace_event(struct perf_session *session,
 				   union perf_event *event __maybe_unused,
-				   struct perf_tool *tool __maybe_unused)
+				   const struct perf_tool *tool __maybe_unused)
 {
 	struct s390_cpumsf *sf = container_of(session->auxtrace,
 					      struct s390_cpumsf,
@@ -998,7 +998,7 @@ static void s390_cpumsf_free_events(struct perf_session *session __maybe_unused)
 }
 
 static int s390_cpumsf_flush(struct perf_session *session __maybe_unused,
-			     struct perf_tool *tool __maybe_unused)
+			     const struct perf_tool *tool __maybe_unused)
 {
 	return 0;
 }
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index aa02c1d7b1f9..41beebd0913c 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -103,7 +103,7 @@ static int perf_session__process_compressed_event(struct perf_session *session,
 
 static int perf_session__deliver_event(struct perf_session *session,
 				       union perf_event *event,
-				       struct perf_tool *tool,
+				       const struct perf_tool *tool,
 				       u64 file_offset,
 				       const char *file_path);
 
@@ -330,7 +330,7 @@ static int process_event_synth_tracing_data_stub(struct perf_session *session
 	return 0;
 }
 
-static int process_event_synth_attr_stub(struct perf_tool *tool __maybe_unused,
+static int process_event_synth_attr_stub(const struct perf_tool *tool __maybe_unused,
 					 union perf_event *event __maybe_unused,
 					 struct evlist **pevlist
 					 __maybe_unused)
@@ -339,7 +339,7 @@ static int process_event_synth_attr_stub(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int process_event_synth_event_update_stub(struct perf_tool *tool __maybe_unused,
+static int process_event_synth_event_update_stub(const struct perf_tool *tool __maybe_unused,
 						 union perf_event *event __maybe_unused,
 						 struct evlist **pevlist
 						 __maybe_unused)
@@ -351,7 +351,7 @@ static int process_event_synth_event_update_stub(struct perf_tool *tool __maybe_
 	return 0;
 }
 
-static int process_event_sample_stub(struct perf_tool *tool __maybe_unused,
+static int process_event_sample_stub(const struct perf_tool *tool __maybe_unused,
 				     union perf_event *event __maybe_unused,
 				     struct perf_sample *sample __maybe_unused,
 				     struct evsel *evsel __maybe_unused,
@@ -361,7 +361,7 @@ static int process_event_sample_stub(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int process_event_stub(struct perf_tool *tool __maybe_unused,
+static int process_event_stub(const struct perf_tool *tool __maybe_unused,
 			      union perf_event *event __maybe_unused,
 			      struct perf_sample *sample __maybe_unused,
 			      struct machine *machine __maybe_unused)
@@ -370,7 +370,7 @@ static int process_event_stub(struct perf_tool *tool __maybe_unused,
 	return 0;
 }
 
-static int process_finished_round_stub(struct perf_tool *tool __maybe_unused,
+static int process_finished_round_stub(const struct perf_tool *tool __maybe_unused,
 				       union perf_event *event __maybe_unused,
 				       struct ordered_events *oe __maybe_unused)
 {
@@ -1078,7 +1078,7 @@ static perf_event__swap_op perf_event__swap_ops[] = {
  *      Flush every events below timestamp 7
  *      etc...
  */
-int perf_event__process_finished_round(struct perf_tool *tool __maybe_unused,
+int perf_event__process_finished_round(const struct perf_tool *tool __maybe_unused,
 				       union perf_event *event __maybe_unused,
 				       struct ordered_events *oe)
 {
@@ -1472,7 +1472,7 @@ static struct machine *machines__find_for_cpumode(struct machines *machines,
 }
 
 static int deliver_sample_value(struct evlist *evlist,
-				struct perf_tool *tool,
+				const struct perf_tool *tool,
 				union perf_event *event,
 				struct perf_sample *sample,
 				struct sample_read_value *v,
@@ -1504,7 +1504,7 @@ static int deliver_sample_value(struct evlist *evlist,
 }
 
 static int deliver_sample_group(struct evlist *evlist,
-				struct perf_tool *tool,
+				const struct perf_tool *tool,
 				union  perf_event *event,
 				struct perf_sample *sample,
 				struct machine *machine,
@@ -1526,7 +1526,7 @@ static int deliver_sample_group(struct evlist *evlist,
 	return ret;
 }
 
-static int evlist__deliver_sample(struct evlist *evlist, struct perf_tool *tool,
+static int evlist__deliver_sample(struct evlist *evlist, const struct perf_tool *tool,
 				  union  perf_event *event, struct perf_sample *sample,
 				  struct evsel *evsel, struct machine *machine)
 {
@@ -1551,7 +1551,7 @@ static int machines__deliver_event(struct machines *machines,
 				   struct evlist *evlist,
 				   union perf_event *event,
 				   struct perf_sample *sample,
-				   struct perf_tool *tool, u64 file_offset,
+				   const struct perf_tool *tool, u64 file_offset,
 				   const char *file_path)
 {
 	struct evsel *evsel;
@@ -1639,7 +1639,7 @@ static int machines__deliver_event(struct machines *machines,
 
 static int perf_session__deliver_event(struct perf_session *session,
 				       union perf_event *event,
-				       struct perf_tool *tool,
+				       const struct perf_tool *tool,
 				       u64 file_offset,
 				       const char *file_path)
 {
@@ -1672,7 +1672,7 @@ static s64 perf_session__process_user_event(struct perf_session *session,
 					    const char *file_path)
 {
 	struct ordered_events *oe = &session->ordered_events;
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct perf_sample sample = { .time = 0, };
 	int fd = perf_data__fd(session->data);
 	int err;
@@ -1759,7 +1759,7 @@ int perf_session__deliver_synth_event(struct perf_session *session,
 				      struct perf_sample *sample)
 {
 	struct evlist *evlist = session->evlist;
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 
 	events_stats__inc(&evlist->stats, event->header.type);
 
@@ -1891,7 +1891,7 @@ static s64 perf_session__process_event(struct perf_session *session,
 				       const char *file_path)
 {
 	struct evlist *evlist = session->evlist;
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	int ret;
 
 	if (session->header.needs_swap)
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index cc28976bb00e..6886cc85600f 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -163,7 +163,7 @@ int perf_session__dsos_hit_all(struct perf_session *session);
 int perf_event__process_id_index(struct perf_session *session,
 				 union perf_event *event);
 
-int perf_event__process_finished_round(struct perf_tool *tool,
+int perf_event__process_finished_round(const struct perf_tool *tool,
 				       union perf_event *event,
 				       struct ordered_events *oe);
 
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index 5498048f56ea..7f884d70de81 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0-only 
+// SPDX-License-Identifier: GPL-2.0-only
 
 #include "util/cgroup.h"
 #include "util/data.h"
@@ -47,7 +47,7 @@
 
 unsigned int proc_map_timeout = DEFAULT_PROC_MAP_PARSE_TIMEOUT;
 
-int perf_tool__process_synth_event(struct perf_tool *tool,
+int perf_tool__process_synth_event(const struct perf_tool *tool,
 				   union perf_event *event,
 				   struct machine *machine,
 				   perf_event__handler_t process)
@@ -187,7 +187,7 @@ static int perf_event__prepare_comm(union perf_event *event, pid_t pid, pid_t ti
 	return 0;
 }
 
-pid_t perf_event__synthesize_comm(struct perf_tool *tool,
+pid_t perf_event__synthesize_comm(const struct perf_tool *tool,
 					 union perf_event *event, pid_t pid,
 					 perf_event__handler_t process,
 					 struct machine *machine)
@@ -218,7 +218,7 @@ static void perf_event__get_ns_link_info(pid_t pid, const char *ns,
 	}
 }
 
-int perf_event__synthesize_namespaces(struct perf_tool *tool,
+int perf_event__synthesize_namespaces(const struct perf_tool *tool,
 				      union perf_event *event,
 				      pid_t pid, pid_t tgid,
 				      perf_event__handler_t process,
@@ -257,7 +257,7 @@ int perf_event__synthesize_namespaces(struct perf_tool *tool,
 	return 0;
 }
 
-static int perf_event__synthesize_fork(struct perf_tool *tool,
+static int perf_event__synthesize_fork(const struct perf_tool *tool,
 				       union perf_event *event,
 				       pid_t pid, pid_t tgid, pid_t ppid,
 				       perf_event__handler_t process,
@@ -418,7 +418,7 @@ out:
 	dso__put(dso);
 }
 
-int perf_event__synthesize_mmap_events(struct perf_tool *tool,
+int perf_event__synthesize_mmap_events(const struct perf_tool *tool,
 				       union perf_event *event,
 				       pid_t pid, pid_t tgid,
 				       perf_event__handler_t process,
@@ -542,7 +542,7 @@ out:
 }
 
 #ifdef HAVE_FILE_HANDLE
-static int perf_event__synthesize_cgroup(struct perf_tool *tool,
+static int perf_event__synthesize_cgroup(const struct perf_tool *tool,
 					 union perf_event *event,
 					 char *path, size_t mount_len,
 					 perf_event__handler_t process,
@@ -582,7 +582,7 @@ static int perf_event__synthesize_cgroup(struct perf_tool *tool,
 	return 0;
 }
 
-static int perf_event__walk_cgroup_tree(struct perf_tool *tool,
+static int perf_event__walk_cgroup_tree(const struct perf_tool *tool,
 					union perf_event *event,
 					char *path, size_t mount_len,
 					perf_event__handler_t process,
@@ -630,7 +630,7 @@ static int perf_event__walk_cgroup_tree(struct perf_tool *tool,
 	return ret;
 }
 
-int perf_event__synthesize_cgroups(struct perf_tool *tool,
+int perf_event__synthesize_cgroups(const struct perf_tool *tool,
 				   perf_event__handler_t process,
 				   struct machine *machine)
 {
@@ -657,7 +657,7 @@ int perf_event__synthesize_cgroups(struct perf_tool *tool,
 	return 0;
 }
 #else
-int perf_event__synthesize_cgroups(struct perf_tool *tool __maybe_unused,
+int perf_event__synthesize_cgroups(const struct perf_tool *tool __maybe_unused,
 				   perf_event__handler_t process __maybe_unused,
 				   struct machine *machine __maybe_unused)
 {
@@ -666,7 +666,7 @@ int perf_event__synthesize_cgroups(struct perf_tool *tool __maybe_unused,
 #endif
 
 struct perf_event__synthesize_modules_maps_cb_args {
-	struct perf_tool *tool;
+	const struct perf_tool *tool;
 	perf_event__handler_t process;
 	struct machine *machine;
 	union perf_event *event;
@@ -717,7 +717,7 @@ static int perf_event__synthesize_modules_maps_cb(struct map *map, void *data)
 	return 0;
 }
 
-int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t process,
+int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process,
 				   struct machine *machine)
 {
 	int rc;
@@ -763,7 +763,7 @@ static int __event__synthesize_thread(union perf_event *comm_event,
 				      union perf_event *fork_event,
 				      union perf_event *namespaces_event,
 				      pid_t pid, int full, perf_event__handler_t process,
-				      struct perf_tool *tool, struct machine *machine,
+				      const struct perf_tool *tool, struct machine *machine,
 				      bool needs_mmap, bool mmap_data)
 {
 	char filename[PATH_MAX];
@@ -852,7 +852,7 @@ static int __event__synthesize_thread(union perf_event *comm_event,
 	return rc;
 }
 
-int perf_event__synthesize_thread_map(struct perf_tool *tool,
+int perf_event__synthesize_thread_map(const struct perf_tool *tool,
 				      struct perf_thread_map *threads,
 				      perf_event__handler_t process,
 				      struct machine *machine,
@@ -929,7 +929,7 @@ out:
 	return err;
 }
 
-static int __perf_event__synthesize_threads(struct perf_tool *tool,
+static int __perf_event__synthesize_threads(const struct perf_tool *tool,
 					    perf_event__handler_t process,
 					    struct machine *machine,
 					    bool needs_mmap,
@@ -993,7 +993,7 @@ out:
 }
 
 struct synthesize_threads_arg {
-	struct perf_tool *tool;
+	const struct perf_tool *tool;
 	perf_event__handler_t process;
 	struct machine *machine;
 	bool needs_mmap;
@@ -1015,7 +1015,7 @@ static void *synthesize_threads_worker(void *arg)
 	return NULL;
 }
 
-int perf_event__synthesize_threads(struct perf_tool *tool,
+int perf_event__synthesize_threads(const struct perf_tool *tool,
 				   perf_event__handler_t process,
 				   struct machine *machine,
 				   bool needs_mmap, bool mmap_data,
@@ -1104,14 +1104,14 @@ free_dirent:
 	return err;
 }
 
-int __weak perf_event__synthesize_extra_kmaps(struct perf_tool *tool __maybe_unused,
+int __weak perf_event__synthesize_extra_kmaps(const struct perf_tool *tool __maybe_unused,
 					      perf_event__handler_t process __maybe_unused,
 					      struct machine *machine __maybe_unused)
 {
 	return 0;
 }
 
-static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
+static int __perf_event__synthesize_kernel_mmap(const struct perf_tool *tool,
 						perf_event__handler_t process,
 						struct machine *machine)
 {
@@ -1183,7 +1183,7 @@ static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
 	return err;
 }
 
-int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
+int perf_event__synthesize_kernel_mmap(const struct perf_tool *tool,
 				       perf_event__handler_t process,
 				       struct machine *machine)
 {
@@ -1196,7 +1196,7 @@ int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
 	return perf_event__synthesize_extra_kmaps(tool, process, machine);
 }
 
-int perf_event__synthesize_thread_map2(struct perf_tool *tool,
+int perf_event__synthesize_thread_map2(const struct perf_tool *tool,
 				      struct perf_thread_map *threads,
 				      perf_event__handler_t process,
 				      struct machine *machine)
@@ -1346,7 +1346,7 @@ static struct perf_record_cpu_map *cpu_map_event__new(const struct perf_cpu_map
 }
 
 
-int perf_event__synthesize_cpu_map(struct perf_tool *tool,
+int perf_event__synthesize_cpu_map(const struct perf_tool *tool,
 				   const struct perf_cpu_map *map,
 				   perf_event__handler_t process,
 				   struct machine *machine)
@@ -1364,7 +1364,7 @@ int perf_event__synthesize_cpu_map(struct perf_tool *tool,
 	return err;
 }
 
-int perf_event__synthesize_stat_config(struct perf_tool *tool,
+int perf_event__synthesize_stat_config(const struct perf_tool *tool,
 				       struct perf_stat_config *config,
 				       perf_event__handler_t process,
 				       struct machine *machine)
@@ -1403,7 +1403,7 @@ int perf_event__synthesize_stat_config(struct perf_tool *tool,
 	return err;
 }
 
-int perf_event__synthesize_stat(struct perf_tool *tool,
+int perf_event__synthesize_stat(const struct perf_tool *tool,
 				struct perf_cpu cpu, u32 thread, u64 id,
 				struct perf_counts_values *count,
 				perf_event__handler_t process,
@@ -1425,7 +1425,7 @@ int perf_event__synthesize_stat(struct perf_tool *tool,
 	return process(tool, (union perf_event *) &event, NULL, machine);
 }
 
-int perf_event__synthesize_stat_round(struct perf_tool *tool,
+int perf_event__synthesize_stat_round(const struct perf_tool *tool,
 				      u64 evtime, u64 type,
 				      perf_event__handler_t process,
 				      struct machine *machine)
@@ -1826,7 +1826,7 @@ int perf_event__synthesize_id_sample(__u64 *array, u64 type, const struct perf_s
 	return (void *)array - (void *)start;
 }
 
-int __perf_event__synthesize_id_index(struct perf_tool *tool, perf_event__handler_t process,
+int __perf_event__synthesize_id_index(const struct perf_tool *tool, perf_event__handler_t process,
 				      struct evlist *evlist, struct machine *machine, size_t from)
 {
 	union perf_event *ev;
@@ -1918,13 +1918,13 @@ out_err:
 	return err;
 }
 
-int perf_event__synthesize_id_index(struct perf_tool *tool, perf_event__handler_t process,
+int perf_event__synthesize_id_index(const struct perf_tool *tool, perf_event__handler_t process,
 				    struct evlist *evlist, struct machine *machine)
 {
 	return __perf_event__synthesize_id_index(tool, process, evlist, machine, 0);
 }
 
-int __machine__synthesize_threads(struct machine *machine, struct perf_tool *tool,
+int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
 				  perf_event__handler_t process, bool needs_mmap,
 				  bool data_mmap, unsigned int nr_threads_synthesize)
@@ -1985,7 +1985,7 @@ static struct perf_record_event_update *event_update_event__new(size_t size, u64
 	return ev;
 }
 
-int perf_event__synthesize_event_update_unit(struct perf_tool *tool, struct evsel *evsel,
+int perf_event__synthesize_event_update_unit(const struct perf_tool *tool, struct evsel *evsel,
 					     perf_event__handler_t process)
 {
 	size_t size = strlen(evsel->unit);
@@ -2002,7 +2002,7 @@ int perf_event__synthesize_event_update_unit(struct perf_tool *tool, struct evse
 	return err;
 }
 
-int perf_event__synthesize_event_update_scale(struct perf_tool *tool, struct evsel *evsel,
+int perf_event__synthesize_event_update_scale(const struct perf_tool *tool, struct evsel *evsel,
 					      perf_event__handler_t process)
 {
 	struct perf_record_event_update *ev;
@@ -2019,7 +2019,7 @@ int perf_event__synthesize_event_update_scale(struct perf_tool *tool, struct evs
 	return err;
 }
 
-int perf_event__synthesize_event_update_name(struct perf_tool *tool, struct evsel *evsel,
+int perf_event__synthesize_event_update_name(const struct perf_tool *tool, struct evsel *evsel,
 					     perf_event__handler_t process)
 {
 	struct perf_record_event_update *ev;
@@ -2036,7 +2036,7 @@ int perf_event__synthesize_event_update_name(struct perf_tool *tool, struct evse
 	return err;
 }
 
-int perf_event__synthesize_event_update_cpus(struct perf_tool *tool, struct evsel *evsel,
+int perf_event__synthesize_event_update_cpus(const struct perf_tool *tool, struct evsel *evsel,
 					     perf_event__handler_t process)
 {
 	struct synthesize_cpu_map_data syn_data = { .map = evsel->core.own_cpus };
@@ -2059,7 +2059,7 @@ int perf_event__synthesize_event_update_cpus(struct perf_tool *tool, struct evse
 	return err;
 }
 
-int perf_event__synthesize_attrs(struct perf_tool *tool, struct evlist *evlist,
+int perf_event__synthesize_attrs(const struct perf_tool *tool, struct evlist *evlist,
 				 perf_event__handler_t process)
 {
 	struct evsel *evsel;
@@ -2087,7 +2087,7 @@ static bool has_scale(struct evsel *evsel)
 	return evsel->scale != 1;
 }
 
-int perf_event__synthesize_extra_attr(struct perf_tool *tool, struct evlist *evsel_list,
+int perf_event__synthesize_extra_attr(const struct perf_tool *tool, struct evlist *evsel_list,
 				      perf_event__handler_t process, bool is_pipe)
 {
 	struct evsel *evsel;
@@ -2143,7 +2143,7 @@ int perf_event__synthesize_extra_attr(struct perf_tool *tool, struct evlist *evs
 	return 0;
 }
 
-int perf_event__synthesize_attr(struct perf_tool *tool, struct perf_event_attr *attr,
+int perf_event__synthesize_attr(const struct perf_tool *tool, struct perf_event_attr *attr,
 				u32 ids, u64 *id, perf_event__handler_t process)
 {
 	union perf_event *ev;
@@ -2177,7 +2177,7 @@ int perf_event__synthesize_attr(struct perf_tool *tool, struct perf_event_attr *
 }
 
 #ifdef HAVE_LIBTRACEEVENT
-int perf_event__synthesize_tracing_data(struct perf_tool *tool, int fd, struct evlist *evlist,
+int perf_event__synthesize_tracing_data(const struct perf_tool *tool, int fd, struct evlist *evlist,
 					perf_event__handler_t process)
 {
 	union perf_event ev;
@@ -2225,7 +2225,7 @@ int perf_event__synthesize_tracing_data(struct perf_tool *tool, int fd, struct e
 }
 #endif
 
-int perf_event__synthesize_build_id(struct perf_tool *tool, struct dso *pos, u16 misc,
+int perf_event__synthesize_build_id(const struct perf_tool *tool, struct dso *pos, u16 misc,
 				    perf_event__handler_t process, struct machine *machine)
 {
 	union perf_event ev;
@@ -2249,7 +2249,7 @@ int perf_event__synthesize_build_id(struct perf_tool *tool, struct dso *pos, u16
 	return process(tool, &ev, NULL, machine);
 }
 
-int perf_event__synthesize_stat_events(struct perf_stat_config *config, struct perf_tool *tool,
+int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool,
 				       struct evlist *evlist, perf_event__handler_t process, bool attrs)
 {
 	int err;
@@ -2286,7 +2286,7 @@ int perf_event__synthesize_stat_events(struct perf_stat_config *config, struct p
 
 extern const struct perf_header_feature_ops feat_ops[HEADER_LAST_FEATURE];
 
-int perf_event__synthesize_features(struct perf_tool *tool, struct perf_session *session,
+int perf_event__synthesize_features(const struct perf_tool *tool, struct perf_session *session,
 				    struct evlist *evlist, perf_event__handler_t process)
 {
 	struct perf_header *header = &session->header;
@@ -2349,7 +2349,7 @@ int perf_event__synthesize_features(struct perf_tool *tool, struct perf_session
 	return ret;
 }
 
-int perf_event__synthesize_for_pipe(struct perf_tool *tool,
+int perf_event__synthesize_for_pipe(const struct perf_tool *tool,
 				    struct perf_session *session,
 				    struct perf_data *data,
 				    perf_event__handler_t process)
diff --git a/tools/perf/util/synthetic-events.h b/tools/perf/util/synthetic-events.h
index 53737d1619a4..31df7653677f 100644
--- a/tools/perf/util/synthetic-events.h
+++ b/tools/perf/util/synthetic-events.h
@@ -40,45 +40,45 @@ enum perf_record_synth {
 
 int parse_synth_opt(char *str);
 
-typedef int (*perf_event__handler_t)(struct perf_tool *tool, union perf_event *event,
+typedef int (*perf_event__handler_t)(const struct perf_tool *tool, union perf_event *event,
 				     struct perf_sample *sample, struct machine *machine);
 
-int perf_event__synthesize_attrs(struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process);
-int perf_event__synthesize_attr(struct perf_tool *tool, struct perf_event_attr *attr, u32 ids, u64 *id, perf_event__handler_t process);
-int perf_event__synthesize_build_id(struct perf_tool *tool, struct dso *pos, u16 misc, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_cpu_map(struct perf_tool *tool, const struct perf_cpu_map *cpus, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_event_update_cpus(struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);
-int perf_event__synthesize_event_update_name(struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);
-int perf_event__synthesize_event_update_scale(struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);
-int perf_event__synthesize_event_update_unit(struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);
-int perf_event__synthesize_extra_attr(struct perf_tool *tool, struct evlist *evsel_list, perf_event__handler_t process, bool is_pipe);
-int perf_event__synthesize_extra_kmaps(struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_features(struct perf_tool *tool, struct perf_session *session, struct evlist *evlist, perf_event__handler_t process);
-int perf_event__synthesize_id_index(struct perf_tool *tool, perf_event__handler_t process, struct evlist *evlist, struct machine *machine);
-int __perf_event__synthesize_id_index(struct perf_tool *tool, perf_event__handler_t process, struct evlist *evlist, struct machine *machine, size_t from);
+int perf_event__synthesize_attrs(const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process);
+int perf_event__synthesize_attr(const struct perf_tool *tool, struct perf_event_attr *attr, u32 ids, u64 *id, perf_event__handler_t process);
+int perf_event__synthesize_build_id(const struct perf_tool *tool, struct dso *pos, u16 misc, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_cpu_map(const struct perf_tool *tool, const struct perf_cpu_map *cpus, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_event_update_cpus(const struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);
+int perf_event__synthesize_event_update_name(const struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);
+int perf_event__synthesize_event_update_scale(const struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);
+int perf_event__synthesize_event_update_unit(const struct perf_tool *tool, struct evsel *evsel, perf_event__handler_t process);
+int perf_event__synthesize_extra_attr(const struct perf_tool *tool, struct evlist *evsel_list, perf_event__handler_t process, bool is_pipe);
+int perf_event__synthesize_extra_kmaps(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_features(const struct perf_tool *tool, struct perf_session *session, struct evlist *evlist, perf_event__handler_t process);
+int perf_event__synthesize_id_index(const struct perf_tool *tool, perf_event__handler_t process, struct evlist *evlist, struct machine *machine);
+int __perf_event__synthesize_id_index(const struct perf_tool *tool, perf_event__handler_t process, struct evlist *evlist, struct machine *machine, size_t from);
 int perf_event__synthesize_id_sample(__u64 *array, u64 type, const struct perf_sample *sample);
-int perf_event__synthesize_kernel_mmap(struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_mmap_events(struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine, bool mmap_data);
-int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_namespaces(struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_cgroups(struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_kernel_mmap(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_mmap_events(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine, bool mmap_data);
+int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_namespaces(const struct perf_tool *tool, union perf_event *event, pid_t pid, pid_t tgid, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_cgroups(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
 int perf_event__synthesize_sample(union perf_event *event, u64 type, u64 read_format, const struct perf_sample *sample);
-int perf_event__synthesize_stat_config(struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_stat_events(struct perf_stat_config *config, struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
-int perf_event__synthesize_stat_round(struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_stat(struct perf_tool *tool, struct perf_cpu cpu, u32 thread, u64 id, struct perf_counts_values *count, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_thread_map2(struct perf_tool *tool, struct perf_thread_map *threads, perf_event__handler_t process, struct machine *machine);
-int perf_event__synthesize_thread_map(struct perf_tool *tool, struct perf_thread_map *threads, perf_event__handler_t process, struct machine *machine, bool needs_mmap, bool mmap_data);
-int perf_event__synthesize_threads(struct perf_tool *tool, perf_event__handler_t process, struct machine *machine, bool needs_mmap, bool mmap_data, unsigned int nr_threads_synthesize);
-int perf_event__synthesize_tracing_data(struct perf_tool *tool, int fd, struct evlist *evlist, perf_event__handler_t process);
-int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc, struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
-pid_t perf_event__synthesize_comm(struct perf_tool *tool, union perf_event *event, pid_t pid, perf_event__handler_t process, struct machine *machine);
-
-int perf_tool__process_synth_event(struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
+int perf_event__synthesize_stat_config(const struct perf_tool *tool, struct perf_stat_config *config, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_stat_events(struct perf_stat_config *config, const struct perf_tool *tool, struct evlist *evlist, perf_event__handler_t process, bool attrs);
+int perf_event__synthesize_stat_round(const struct perf_tool *tool, u64 time, u64 type, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_stat(const struct perf_tool *tool, struct perf_cpu cpu, u32 thread, u64 id, struct perf_counts_values *count, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_thread_map2(const struct perf_tool *tool, struct perf_thread_map *threads, perf_event__handler_t process, struct machine *machine);
+int perf_event__synthesize_thread_map(const struct perf_tool *tool, struct perf_thread_map *threads, perf_event__handler_t process, struct machine *machine, bool needs_mmap, bool mmap_data);
+int perf_event__synthesize_threads(const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine, bool needs_mmap, bool mmap_data, unsigned int nr_threads_synthesize);
+int perf_event__synthesize_tracing_data(const struct perf_tool *tool, int fd, struct evlist *evlist, perf_event__handler_t process);
+int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc, const struct perf_tool *tool, perf_event__handler_t process, struct machine *machine);
+pid_t perf_event__synthesize_comm(const struct perf_tool *tool, union perf_event *event, pid_t pid, perf_event__handler_t process, struct machine *machine);
+
+int perf_tool__process_synth_event(const struct perf_tool *tool, union perf_event *event, struct machine *machine, perf_event__handler_t process);
 
 size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type, u64 read_format);
 
-int __machine__synthesize_threads(struct machine *machine, struct perf_tool *tool,
+int __machine__synthesize_threads(struct machine *machine, const struct perf_tool *tool,
 				  struct target *target, struct perf_thread_map *threads,
 				  perf_event__handler_t process, bool needs_mmap, bool data_mmap,
 				  unsigned int nr_threads_synthesize);
@@ -87,7 +87,7 @@ int machine__synthesize_threads(struct machine *machine, struct target *target,
 				unsigned int nr_threads_synthesize);
 
 #ifdef HAVE_AUXTRACE_SUPPORT
-int perf_event__synthesize_auxtrace_info(struct auxtrace_record *itr, struct perf_tool *tool,
+int perf_event__synthesize_auxtrace_info(struct auxtrace_record *itr, const struct perf_tool *tool,
 					 struct perf_session *session, perf_event__handler_t process);
 
 #else // HAVE_AUXTRACE_SUPPORT
@@ -96,7 +96,7 @@ int perf_event__synthesize_auxtrace_info(struct auxtrace_record *itr, struct per
 
 static inline int
 perf_event__synthesize_auxtrace_info(struct auxtrace_record *itr __maybe_unused,
-				     struct perf_tool *tool __maybe_unused,
+				     const struct perf_tool *tool __maybe_unused,
 				     struct perf_session *session __maybe_unused,
 				     perf_event__handler_t process __maybe_unused)
 {
@@ -117,7 +117,7 @@ static inline int perf_event__synthesize_bpf_events(struct perf_session *session
 }
 #endif // HAVE_LIBBPF_SUPPORT
 
-int perf_event__synthesize_for_pipe(struct perf_tool *tool,
+int perf_event__synthesize_for_pipe(const struct perf_tool *tool,
 				    struct perf_session *session,
 				    struct perf_data *data,
 				    perf_event__handler_t process);
diff --git a/tools/perf/util/tool.h b/tools/perf/util/tool.h
index 62bbc9cec151..2b12c674768f 100644
--- a/tools/perf/util/tool.h
+++ b/tools/perf/util/tool.h
@@ -15,14 +15,14 @@ struct perf_tool;
 struct machine;
 struct ordered_events;
 
-typedef int (*event_sample)(struct perf_tool *tool, union perf_event *event,
+typedef int (*event_sample)(const struct perf_tool *tool, union perf_event *event,
 			    struct perf_sample *sample,
 			    struct evsel *evsel, struct machine *machine);
 
-typedef int (*event_op)(struct perf_tool *tool, union perf_event *event,
+typedef int (*event_op)(const struct perf_tool *tool, union perf_event *event,
 			struct perf_sample *sample, struct machine *machine);
 
-typedef int (*event_attr_op)(struct perf_tool *tool,
+typedef int (*event_attr_op)(const struct perf_tool *tool,
 			     union perf_event *event,
 			     struct evlist **pevlist);
 
@@ -31,7 +31,7 @@ typedef s64 (*event_op3)(struct perf_session *session, union perf_event *event);
 typedef int (*event_op4)(struct perf_session *session, union perf_event *event, u64 data,
 			 const char *str);
 
-typedef int (*event_oe)(struct perf_tool *tool, union perf_event *event,
+typedef int (*event_oe)(const struct perf_tool *tool, union perf_event *event,
 			struct ordered_events *oe);
 
 enum show_feature_header {
diff --git a/tools/perf/util/tsc.c b/tools/perf/util/tsc.c
index f19791d46e99..2e33a20e1e1b 100644
--- a/tools/perf/util/tsc.c
+++ b/tools/perf/util/tsc.c
@@ -72,7 +72,7 @@ int perf_read_tsc_conversion(const struct perf_event_mmap_page *pc,
 }
 
 int perf_event__synth_time_conv(const struct perf_event_mmap_page *pc,
-				struct perf_tool *tool,
+				const struct perf_tool *tool,
 				perf_event__handler_t process,
 				struct machine *machine)
 {