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authorNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>2017-03-08 09:26:09 +0100
committerArnaldo Carvalho de Melo <acme@redhat.com>2017-03-14 19:17:39 +0100
commit7ab31d94bff96f4f80b38dc5147622b9f3889ac6 (patch)
tree158fb2762dd41bd84f17ed3fb3c7e5882d5b7009
parentperf probe: Factor out the ftrace README scanning (diff)
downloadlinux-7ab31d94bff96f4f80b38dc5147622b9f3889ac6.tar.xz
linux-7ab31d94bff96f4f80b38dc5147622b9f3889ac6.zip
perf kretprobes: Offset from reloc_sym if kernel supports it
We indicate support for accepting sym+offset with kretprobes through a line in ftrace README. Parse the same to identify support and choose the appropriate format for kprobe_events. As an example, without this perf patch, but with the ftrace changes: naveen@ubuntu:~/linux/tools/perf$ sudo cat /sys/kernel/debug/tracing/README | grep kretprobe place (kretprobe): [<module>:]<symbol>[+<offset>]|<memaddr> naveen@ubuntu:~/linux/tools/perf$ naveen@ubuntu:~/linux/tools/perf$ sudo ./perf probe -v do_open%return probe-definition(0): do_open%return symbol:do_open file:(null) line:0 offset:0 return:1 lazy:(null) 0 arguments Looking at the vmlinux_path (8 entries long) Using /boot/vmlinux for symbols Open Debuginfo file: /boot/vmlinux Try to find probe point from debuginfo. Matched function: do_open [2d0c7d8] Probe point found: do_open+0 Matched function: do_open [35d76b5] found inline addr: 0xc0000000004ba984 Failed to find "do_open%return", because do_open is an inlined function and has no return point. An error occurred in debuginfo analysis (-22). Trying to use symbols. Opening /sys/kernel/debug/tracing//kprobe_events write=1 Writing event: r:probe/do_open do_open+0 Writing event: r:probe/do_open_1 do_open+0 Added new events: probe:do_open (on do_open%return) probe:do_open_1 (on do_open%return) You can now use it in all perf tools, such as: perf record -e probe:do_open_1 -aR sleep 1 naveen@ubuntu:~/linux/tools/perf$ sudo cat /sys/kernel/debug/kprobes/list c000000000041370 k kretprobe_trampoline+0x0 [OPTIMIZED] c0000000004433d0 r do_open+0x0 [DISABLED] c0000000004433d0 r do_open+0x0 [DISABLED] And after this patch (and the subsequent powerpc patch): naveen@ubuntu:~/linux/tools/perf$ sudo ./perf probe -v do_open%return probe-definition(0): do_open%return symbol:do_open file:(null) line:0 offset:0 return:1 lazy:(null) 0 arguments Looking at the vmlinux_path (8 entries long) Using /boot/vmlinux for symbols Open Debuginfo file: /boot/vmlinux Try to find probe point from debuginfo. Matched function: do_open [2d0c7d8] Probe point found: do_open+0 Matched function: do_open [35d76b5] found inline addr: 0xc0000000004ba984 Failed to find "do_open%return", because do_open is an inlined function and has no return point. An error occurred in debuginfo analysis (-22). Trying to use symbols. Opening /sys/kernel/debug/tracing//README write=0 Opening /sys/kernel/debug/tracing//kprobe_events write=1 Writing event: r:probe/do_open _text+4469712 Writing event: r:probe/do_open_1 _text+4956248 Added new events: probe:do_open (on do_open%return) probe:do_open_1 (on do_open%return) You can now use it in all perf tools, such as: perf record -e probe:do_open_1 -aR sleep 1 naveen@ubuntu:~/linux/tools/perf$ sudo cat /sys/kernel/debug/kprobes/list c000000000041370 k kretprobe_trampoline+0x0 [OPTIMIZED] c0000000004433d0 r do_open+0x0 [DISABLED] c0000000004ba058 r do_open+0x8 [DISABLED] Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/496ef9f33c1ab16286ece9dd62aa672807aef91c.1488961018.git.naveen.n.rao@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
-rw-r--r--tools/perf/util/probe-event.c12
-rw-r--r--tools/perf/util/probe-file.c7
-rw-r--r--tools/perf/util/probe-file.h1
3 files changed, 13 insertions, 7 deletions
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 28fb62c32678..c9bdc9ded0c3 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -757,7 +757,9 @@ post_process_kernel_probe_trace_events(struct probe_trace_event *tevs,
}
for (i = 0; i < ntevs; i++) {
- if (!tevs[i].point.address || tevs[i].point.retprobe)
+ if (!tevs[i].point.address)
+ continue;
+ if (tevs[i].point.retprobe && !kretprobe_offset_is_supported())
continue;
/* If we found a wrong one, mark it by NULL symbol */
if (kprobe_warn_out_range(tevs[i].point.symbol,
@@ -1528,11 +1530,6 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
return -EINVAL;
}
- if (pp->retprobe && !pp->function) {
- semantic_error("Return probe requires an entry function.\n");
- return -EINVAL;
- }
-
if ((pp->offset || pp->line || pp->lazy_line) && pp->retprobe) {
semantic_error("Offset/Line/Lazy pattern can't be used with "
"return probe.\n");
@@ -2841,7 +2838,8 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
}
/* Note that the symbols in the kmodule are not relocated */
- if (!pev->uprobes && !pp->retprobe && !pev->target) {
+ if (!pev->uprobes && !pev->target &&
+ (!pp->retprobe || kretprobe_offset_is_supported())) {
reloc_sym = kernel_get_ref_reloc_sym();
if (!reloc_sym) {
pr_warning("Relocated base symbol is not found!\n");
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 8a219cd831b7..1542cd0d6799 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -879,6 +879,7 @@ int probe_cache__show_all_caches(struct strfilter *filter)
enum ftrace_readme {
FTRACE_README_PROBE_TYPE_X = 0,
+ FTRACE_README_KRETPROBE_OFFSET,
FTRACE_README_END,
};
@@ -889,6 +890,7 @@ static struct {
#define DEFINE_TYPE(idx, pat) \
[idx] = {.pattern = pat, .avail = false}
DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"),
+ DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"),
};
static bool scan_ftrace_readme(enum ftrace_readme type)
@@ -939,3 +941,8 @@ bool probe_type_is_available(enum probe_type type)
return true;
}
+
+bool kretprobe_offset_is_supported(void)
+{
+ return scan_ftrace_readme(FTRACE_README_KRETPROBE_OFFSET);
+}
diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
index a17a82eff8a0..dbf95a00864a 100644
--- a/tools/perf/util/probe-file.h
+++ b/tools/perf/util/probe-file.h
@@ -65,6 +65,7 @@ struct probe_cache_entry *probe_cache__find_by_name(struct probe_cache *pcache,
const char *group, const char *event);
int probe_cache__show_all_caches(struct strfilter *filter);
bool probe_type_is_available(enum probe_type type);
+bool kretprobe_offset_is_supported(void);
#else /* ! HAVE_LIBELF_SUPPORT */
static inline struct probe_cache *probe_cache__new(const char *tgt __maybe_unused)
{