From 6d2d73cdd673d493f9f3751188757129b1d23fb7 Mon Sep 17 00:00:00 2001 From: Quentin Monnet <quentin@isovalent.com> Date: Thu, 29 Jul 2021 17:20:21 +0100 Subject: libbpf: Return non-null error on failures in libbpf_find_prog_btf_id() Variable "err" is initialised to -EINVAL so that this error code is returned when something goes wrong in libbpf_find_prog_btf_id(). However, a recent change in the function made use of the variable in such a way that it is set to 0 if retrieving linear information on the program is successful, and this 0 value remains if we error out on failures at later stages. Let's fix this by setting err to -EINVAL later in the function. Fixes: e9fc3ce99b34 ("libbpf: Streamline error reporting for high-level APIs") Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210729162028.29512-2-quentin@isovalent.com --- tools/lib/bpf/libbpf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a1ca6fb0c6d8..7b2b5d261a08 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -8317,7 +8317,7 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) struct bpf_prog_info_linear *info_linear; struct bpf_prog_info *info; struct btf *btf = NULL; - int err = -EINVAL; + int err; info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0); err = libbpf_get_error(info_linear); @@ -8326,6 +8326,8 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) attach_prog_fd); return err; } + + err = -EINVAL; info = &info_linear->info; if (!info->btf_id) { pr_warn("The target program doesn't have BTF\n"); -- cgit v1.2.3 From 3c7e58590600eca3402f08e7fbdf4f2d1e36c5c8 Mon Sep 17 00:00:00 2001 From: Quentin Monnet <quentin@isovalent.com> Date: Thu, 29 Jul 2021 17:20:22 +0100 Subject: libbpf: Rename btf__load() as btf__load_into_kernel() As part of the effort to move towards a v1.0 for libbpf, rename btf__load() function, used to "upload" BTF information into the kernel, as btf__load_into_kernel(). This new name better reflects what the function does. References: - https://github.com/libbpf/libbpf/issues/278 - https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#btfh-apis Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20210729162028.29512-3-quentin@isovalent.com --- tools/lib/bpf/btf.c | 3 ++- tools/lib/bpf/btf.h | 1 + tools/lib/bpf/libbpf.c | 2 +- tools/lib/bpf/libbpf.map | 1 + 4 files changed, 5 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index b46760b93bb4..7e0de560490e 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -1180,7 +1180,7 @@ int btf__finalize_data(struct bpf_object *obj, struct btf *btf) static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian); -int btf__load(struct btf *btf) +int btf__load_into_kernel(struct btf *btf) { __u32 log_buf_size = 0, raw_size; char *log_buf = NULL; @@ -1228,6 +1228,7 @@ done: free(log_buf); return libbpf_err(err); } +int btf__load(struct btf *) __attribute__((alias("btf__load_into_kernel"))); int btf__fd(const struct btf *btf) { diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 374e9f15de2e..fd8a21d936ef 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -46,6 +46,7 @@ LIBBPF_API struct btf *btf__parse_raw_split(const char *path, struct btf *base_b LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf); LIBBPF_API int btf__load(struct btf *btf); +LIBBPF_API int btf__load_into_kernel(struct btf *btf); LIBBPF_API __s32 btf__find_by_name(const struct btf *btf, const char *type_name); LIBBPF_API __s32 btf__find_by_name_kind(const struct btf *btf, diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 7b2b5d261a08..9a657d6d7da3 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2769,7 +2769,7 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj) */ btf__set_fd(kern_btf, 0); } else { - err = btf__load(kern_btf); + err = btf__load_into_kernel(kern_btf); } if (sanitize) { if (!err) { diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index c240d488eb5e..4d80eb8c56b0 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -375,6 +375,7 @@ LIBBPF_0.5.0 { bpf_map_lookup_and_delete_elem_flags; bpf_program__attach_kprobe_opts; bpf_object__gen_loader; + btf__load_into_kernel; btf_dump__dump_type_data; libbpf_set_strict_mode; } LIBBPF_0.4.0; -- cgit v1.2.3 From 6cc93e2f2c1c865acadedfea174bde893a2aa376 Mon Sep 17 00:00:00 2001 From: Quentin Monnet <quentin@isovalent.com> Date: Thu, 29 Jul 2021 17:20:23 +0100 Subject: libbpf: Rename btf__get_from_id() as btf__load_from_kernel_by_id() Rename function btf__get_from_id() as btf__load_from_kernel_by_id() to better indicate what the function does. Change the new function so that, instead of requiring a pointer to the pointer to update and returning with an error code, it takes a single argument (the id of the BTF object) and returns the corresponding pointer. This is more in line with the existing constructors. The other tools calling the (soon-to-be) deprecated btf__get_from_id() function will be updated in a future commit. References: - https://github.com/libbpf/libbpf/issues/278 - https://github.com/libbpf/libbpf/wiki/Libbpf:-the-road-to-v1.0#btfh-apis Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20210729162028.29512-4-quentin@isovalent.com --- tools/lib/bpf/btf.c | 25 +++++++++++++++++-------- tools/lib/bpf/btf.h | 4 +++- tools/lib/bpf/libbpf.c | 5 +++-- tools/lib/bpf/libbpf.map | 1 + 4 files changed, 24 insertions(+), 11 deletions(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 7e0de560490e..948c29fee447 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -1383,21 +1383,30 @@ exit_free: return btf; } -int btf__get_from_id(__u32 id, struct btf **btf) +struct btf *btf__load_from_kernel_by_id(__u32 id) { - struct btf *res; - int err, btf_fd; + struct btf *btf; + int btf_fd; - *btf = NULL; btf_fd = bpf_btf_get_fd_by_id(id); if (btf_fd < 0) - return libbpf_err(-errno); - - res = btf_get_from_fd(btf_fd, NULL); - err = libbpf_get_error(res); + return libbpf_err_ptr(-errno); + btf = btf_get_from_fd(btf_fd, NULL); close(btf_fd); + return libbpf_ptr(btf); +} + +int btf__get_from_id(__u32 id, struct btf **btf) +{ + struct btf *res; + int err; + + *btf = NULL; + res = btf__load_from_kernel_by_id(id); + err = libbpf_get_error(res); + if (err) return libbpf_err(err); diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index fd8a21d936ef..5d955329a1f4 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -44,6 +44,9 @@ LIBBPF_API struct btf *btf__parse_elf_split(const char *path, struct btf *base_b LIBBPF_API struct btf *btf__parse_raw(const char *path); LIBBPF_API struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf); +LIBBPF_API struct btf *btf__load_from_kernel_by_id(__u32 id); +LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf); + LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf); LIBBPF_API int btf__load(struct btf *btf); LIBBPF_API int btf__load_into_kernel(struct btf *btf); @@ -67,7 +70,6 @@ LIBBPF_API void btf__set_fd(struct btf *btf, int fd); LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size); LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset); LIBBPF_API const char *btf__str_by_offset(const struct btf *btf, __u32 offset); -LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf); LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name, __u32 expected_key_size, __u32 expected_value_size, diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 9a657d6d7da3..313883179919 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -8316,7 +8316,7 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) { struct bpf_prog_info_linear *info_linear; struct bpf_prog_info *info; - struct btf *btf = NULL; + struct btf *btf; int err; info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0); @@ -8333,7 +8333,8 @@ static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd) pr_warn("The target program doesn't have BTF\n"); goto out; } - if (btf__get_from_id(info->btf_id, &btf)) { + btf = btf__load_from_kernel_by_id(info->btf_id); + if (libbpf_get_error(btf)) { pr_warn("Failed to get BTF of the program\n"); goto out; } diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 4d80eb8c56b0..3a9c6939301e 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -375,6 +375,7 @@ LIBBPF_0.5.0 { bpf_map_lookup_and_delete_elem_flags; bpf_program__attach_kprobe_opts; bpf_object__gen_loader; + btf__load_from_kernel_by_id; btf__load_into_kernel; btf_dump__dump_type_data; libbpf_set_strict_mode; -- cgit v1.2.3 From 369e955b3d1c12f6ec2e51a95911bb80ada55d79 Mon Sep 17 00:00:00 2001 From: Quentin Monnet <quentin@isovalent.com> Date: Thu, 29 Jul 2021 17:20:24 +0100 Subject: tools: Free BTF objects at various locations Make sure to call btf__free() (and not simply free(), which does not free all pointers stored in the struct) on pointers to struct btf objects retrieved at various locations. These were found while updating the calls to btf__get_from_id(). Fixes: 999d82cbc044 ("tools/bpf: enhance test_btf file testing to test func info") Fixes: 254471e57a86 ("tools/bpf: bpftool: add support for func types") Fixes: 7b612e291a5a ("perf tools: Synthesize PERF_RECORD_* for loaded BPF programs") Fixes: d56354dc4909 ("perf tools: Save bpf_prog_info and BTF of new BPF programs") Fixes: 47c09d6a9f67 ("bpftool: Introduce "prog profile" command") Fixes: fa853c4b839e ("perf stat: Enable counting events for BPF programs") Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210729162028.29512-5-quentin@isovalent.com --- tools/bpf/bpftool/prog.c | 5 ++++- tools/perf/util/bpf-event.c | 4 ++-- tools/perf/util/bpf_counter.c | 3 ++- tools/testing/selftests/bpf/prog_tests/btf.c | 1 + 4 files changed, 9 insertions(+), 4 deletions(-) diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index cc48726740ad..9d709b427665 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -781,6 +781,8 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode, kernel_syms_destroy(&dd); } + btf__free(btf); + return 0; } @@ -2002,8 +2004,8 @@ static char *profile_target_name(int tgt_fd) struct bpf_prog_info_linear *info_linear; struct bpf_func_info *func_info; const struct btf_type *t; + struct btf *btf = NULL; char *name = NULL; - struct btf *btf; info_linear = bpf_program__get_prog_info_linear( tgt_fd, 1UL << BPF_PROG_INFO_FUNC_INFO); @@ -2027,6 +2029,7 @@ static char *profile_target_name(int tgt_fd) } name = strdup(btf__name_by_offset(btf, t->name_off)); out: + btf__free(btf); free(info_linear); return name; } diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c index cdecda1ddd36..17a9844e4fbf 100644 --- a/tools/perf/util/bpf-event.c +++ b/tools/perf/util/bpf-event.c @@ -296,7 +296,7 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session, out: free(info_linear); - free(btf); + btf__free(btf); return err ? -1 : 0; } @@ -486,7 +486,7 @@ static void perf_env__add_bpf_info(struct perf_env *env, u32 id) perf_env__fetch_btf(env, btf_id, btf); out: - free(btf); + btf__free(btf); close(fd); } diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c index 8150e03367bb..beca55129b0b 100644 --- a/tools/perf/util/bpf_counter.c +++ b/tools/perf/util/bpf_counter.c @@ -64,8 +64,8 @@ static char *bpf_target_prog_name(int tgt_fd) struct bpf_prog_info_linear *info_linear; struct bpf_func_info *func_info; const struct btf_type *t; + struct btf *btf = NULL; char *name = NULL; - struct btf *btf; info_linear = bpf_program__get_prog_info_linear( tgt_fd, 1UL << BPF_PROG_INFO_FUNC_INFO); @@ -89,6 +89,7 @@ static char *bpf_target_prog_name(int tgt_fd) } name = strdup(btf__name_by_offset(btf, t->name_off)); out: + btf__free(btf); free(info_linear); return name; } diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c index 857e3f26086f..68e415f4d33c 100644 --- a/tools/testing/selftests/bpf/prog_tests/btf.c +++ b/tools/testing/selftests/bpf/prog_tests/btf.c @@ -4386,6 +4386,7 @@ skip: fprintf(stderr, "OK"); done: + btf__free(btf); free(func_info); bpf_object__close(obj); } -- cgit v1.2.3 From 86f4b7f2578f69284fa782be54e700c42c757897 Mon Sep 17 00:00:00 2001 From: Quentin Monnet <quentin@isovalent.com> Date: Thu, 29 Jul 2021 17:20:25 +0100 Subject: tools: Replace btf__get_from_id() with btf__load_from_kernel_by_id() Replace the calls to function btf__get_from_id(), which we plan to deprecate before the library reaches v1.0, with calls to btf__load_from_kernel_by_id() in tools/ (bpftool, perf, selftests). Update the surrounding code accordingly (instead of passing a pointer to the btf struct, get it as a return value from the function). Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20210729162028.29512-6-quentin@isovalent.com --- tools/bpf/bpftool/btf.c | 8 ++------ tools/bpf/bpftool/btf_dumper.c | 6 ++++-- tools/bpf/bpftool/map.c | 14 +++++++------- tools/bpf/bpftool/prog.c | 24 ++++++++++++++++-------- tools/perf/util/bpf-event.c | 7 ++++--- tools/perf/util/bpf_counter.c | 9 +++++++-- tools/testing/selftests/bpf/prog_tests/btf.c | 3 ++- 7 files changed, 42 insertions(+), 29 deletions(-) diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 385d5c955cf3..9162a18e84c0 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -580,16 +580,12 @@ static int do_dump(int argc, char **argv) } if (!btf) { - err = btf__get_from_id(btf_id, &btf); + btf = btf__load_from_kernel_by_id(btf_id); + err = libbpf_get_error(btf); if (err) { p_err("get btf by id (%u): %s", btf_id, strerror(err)); goto done; } - if (!btf) { - err = -ENOENT; - p_err("can't find btf with ID (%u)", btf_id); - goto done; - } } if (dump_c) { diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c index 7ca54d046362..9c25286a5c73 100644 --- a/tools/bpf/bpftool/btf_dumper.c +++ b/tools/bpf/bpftool/btf_dumper.c @@ -64,8 +64,10 @@ static int dump_prog_id_as_func_ptr(const struct btf_dumper *d, } info = &prog_info->info; - if (!info->btf_id || !info->nr_func_info || - btf__get_from_id(info->btf_id, &prog_btf)) + if (!info->btf_id || !info->nr_func_info) + goto print; + prog_btf = btf__load_from_kernel_by_id(info->btf_id); + if (libbpf_get_error(prog_btf)) goto print; finfo = u64_to_ptr(info->func_info); func_type = btf__type_by_id(prog_btf, finfo->type_id); diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c index 09ae0381205b..7e7f748bb0be 100644 --- a/tools/bpf/bpftool/map.c +++ b/tools/bpf/bpftool/map.c @@ -807,10 +807,11 @@ static struct btf *get_map_kv_btf(const struct bpf_map_info *info) } else if (info->btf_value_type_id) { int err; - err = btf__get_from_id(info->btf_id, &btf); - if (err || !btf) { + btf = btf__load_from_kernel_by_id(info->btf_id); + err = libbpf_get_error(btf); + if (err) { p_err("failed to get btf"); - btf = err ? ERR_PTR(err) : ERR_PTR(-ESRCH); + btf = ERR_PTR(err); } } @@ -1039,11 +1040,10 @@ static void print_key_value(struct bpf_map_info *info, void *key, void *value) { json_writer_t *btf_wtr; - struct btf *btf = NULL; - int err; + struct btf *btf; - err = btf__get_from_id(info->btf_id, &btf); - if (err) { + btf = btf__load_from_kernel_by_id(info->btf_id); + if (libbpf_get_error(btf)) { p_err("failed to get btf"); return; } diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index 9d709b427665..b1996b8f1d42 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -249,10 +249,10 @@ static void show_prog_metadata(int fd, __u32 num_maps) struct bpf_map_info map_info; struct btf_var_secinfo *vsi; bool printed_header = false; - struct btf *btf = NULL; unsigned int i, vlen; void *value = NULL; const char *name; + struct btf *btf; int err; if (!num_maps) @@ -263,8 +263,8 @@ static void show_prog_metadata(int fd, __u32 num_maps) if (!value) return; - err = btf__get_from_id(map_info.btf_id, &btf); - if (err || !btf) + btf = btf__load_from_kernel_by_id(map_info.btf_id); + if (libbpf_get_error(btf)) goto out_free; t_datasec = btf__type_by_id(btf, map_info.btf_value_type_id); @@ -646,9 +646,12 @@ prog_dump(struct bpf_prog_info *info, enum dump_mode mode, member_len = info->xlated_prog_len; } - if (info->btf_id && btf__get_from_id(info->btf_id, &btf)) { - p_err("failed to get btf"); - return -1; + if (info->btf_id) { + btf = btf__load_from_kernel_by_id(info->btf_id); + if (libbpf_get_error(btf)) { + p_err("failed to get btf"); + return -1; + } } func_info = u64_to_ptr(info->func_info); @@ -2014,12 +2017,17 @@ static char *profile_target_name(int tgt_fd) return NULL; } - if (info_linear->info.btf_id == 0 || - btf__get_from_id(info_linear->info.btf_id, &btf)) { + if (info_linear->info.btf_id == 0) { p_err("prog FD %d doesn't have valid btf", tgt_fd); goto out; } + btf = btf__load_from_kernel_by_id(info_linear->info.btf_id); + if (libbpf_get_error(btf)) { + p_err("failed to load btf for prog FD %d", tgt_fd); + goto out; + } + func_info = u64_to_ptr(info_linear->info.func_info); t = btf__type_by_id(btf, func_info[0].type_id); if (!t) { diff --git a/tools/perf/util/bpf-event.c b/tools/perf/util/bpf-event.c index 17a9844e4fbf..996d025b8ed8 100644 --- a/tools/perf/util/bpf-event.c +++ b/tools/perf/util/bpf-event.c @@ -223,10 +223,10 @@ static int perf_event__synthesize_one_bpf_prog(struct perf_session *session, free(info_linear); return -1; } - if (btf__get_from_id(info->btf_id, &btf)) { + btf = btf__load_from_kernel_by_id(info->btf_id); + if (libbpf_get_error(btf)) { pr_debug("%s: failed to get BTF of id %u, aborting\n", __func__, info->btf_id); err = -1; - btf = NULL; goto out; } perf_env__fetch_btf(env, info->btf_id, btf); @@ -478,7 +478,8 @@ static void perf_env__add_bpf_info(struct perf_env *env, u32 id) if (btf_id == 0) goto out; - if (btf__get_from_id(btf_id, &btf)) { + btf = btf__load_from_kernel_by_id(btf_id); + if (libbpf_get_error(btf)) { pr_debug("%s: failed to get BTF of id %u, aborting\n", __func__, btf_id); goto out; diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c index beca55129b0b..ba0f20853651 100644 --- a/tools/perf/util/bpf_counter.c +++ b/tools/perf/util/bpf_counter.c @@ -74,12 +74,17 @@ static char *bpf_target_prog_name(int tgt_fd) return NULL; } - if (info_linear->info.btf_id == 0 || - btf__get_from_id(info_linear->info.btf_id, &btf)) { + if (info_linear->info.btf_id == 0) { pr_debug("prog FD %d doesn't have valid btf\n", tgt_fd); goto out; } + btf = btf__load_from_kernel_by_id(info_linear->info.btf_id); + if (libbpf_get_error(btf)) { + pr_debug("failed to load btf for prog FD %d\n", tgt_fd); + goto out; + } + func_info = u64_to_ptr(info_linear->info.func_info); t = btf__type_by_id(btf, func_info[0].type_id); if (!t) { diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c index 68e415f4d33c..649f87382c8d 100644 --- a/tools/testing/selftests/bpf/prog_tests/btf.c +++ b/tools/testing/selftests/bpf/prog_tests/btf.c @@ -4350,7 +4350,8 @@ static void do_test_file(unsigned int test_num) goto done; } - err = btf__get_from_id(info.btf_id, &btf); + btf = btf__load_from_kernel_by_id(info.btf_id); + err = libbpf_get_error(btf); if (CHECK(err, "cannot get btf from kernel, err: %d", err)) goto done; -- cgit v1.2.3 From 61fc51b1d3e5915e356f2c0b67cd3bb13b640413 Mon Sep 17 00:00:00 2001 From: Quentin Monnet <quentin@isovalent.com> Date: Thu, 29 Jul 2021 17:20:27 +0100 Subject: libbpf: Add split BTF support for btf__load_from_kernel_by_id() Add a new API function btf__load_from_kernel_by_id_split(), which takes a pointer to a base BTF object in order to support split BTF objects when retrieving BTF information from the kernel. Reference: https://github.com/libbpf/libbpf/issues/314 Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20210729162028.29512-8-quentin@isovalent.com --- tools/lib/bpf/btf.c | 9 +++++++-- tools/lib/bpf/btf.h | 1 + tools/lib/bpf/libbpf.map | 1 + 3 files changed, 9 insertions(+), 2 deletions(-) diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 948c29fee447..cafa4f6bd9b1 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -1383,7 +1383,7 @@ exit_free: return btf; } -struct btf *btf__load_from_kernel_by_id(__u32 id) +struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf) { struct btf *btf; int btf_fd; @@ -1392,12 +1392,17 @@ struct btf *btf__load_from_kernel_by_id(__u32 id) if (btf_fd < 0) return libbpf_err_ptr(-errno); - btf = btf_get_from_fd(btf_fd, NULL); + btf = btf_get_from_fd(btf_fd, base_btf); close(btf_fd); return libbpf_ptr(btf); } +struct btf *btf__load_from_kernel_by_id(__u32 id) +{ + return btf__load_from_kernel_by_id_split(id, NULL); +} + int btf__get_from_id(__u32 id, struct btf **btf) { struct btf *res; diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 5d955329a1f4..596a42c8f4f5 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -45,6 +45,7 @@ LIBBPF_API struct btf *btf__parse_raw(const char *path); LIBBPF_API struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf); LIBBPF_API struct btf *btf__load_from_kernel_by_id(__u32 id); +LIBBPF_API struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf); LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf); LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf); diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 3a9c6939301e..5aca3686ca5e 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -376,6 +376,7 @@ LIBBPF_0.5.0 { bpf_program__attach_kprobe_opts; bpf_object__gen_loader; btf__load_from_kernel_by_id; + btf__load_from_kernel_by_id_split; btf__load_into_kernel; btf_dump__dump_type_data; libbpf_set_strict_mode; -- cgit v1.2.3 From 211ab78f7658b50ea10c4569be63ca5009fd39b4 Mon Sep 17 00:00:00 2001 From: Quentin Monnet <quentin@isovalent.com> Date: Thu, 29 Jul 2021 17:20:28 +0100 Subject: tools: bpftool: Support dumping split BTF by id Split BTF objects are typically BTF objects for kernel modules, which are incrementally built on top of kernel BTF instead of redefining all kernel symbols they need. We can use bpftool with its -B command-line option to dump split BTF objects. It works well when the handle provided for the BTF object to dump is a "path" to the BTF object, typically under /sys/kernel/btf, because bpftool internally calls btf__parse_split() which can take a "base_btf" pointer and resolve the BTF reconstruction (although in that case, the "-B" option is unnecessary because bpftool performs autodetection). However, it did not work so far when passing the BTF object through its id, because bpftool would call btf__get_from_id() which did not provide a way to pass a "base_btf" pointer. In other words, the following works: # bpftool btf dump file /sys/kernel/btf/i2c_smbus -B /sys/kernel/btf/vmlinux But this was not possible: # bpftool btf dump id 6 -B /sys/kernel/btf/vmlinux The libbpf API has recently changed, and btf__get_from_id() has been deprecated in favour of btf__load_from_kernel_by_id() and its version with support for split BTF, btf__load_from_kernel_by_id_split(). Let's update bpftool to make it able to dump the BTF object in the second case as well. Signed-off-by: Quentin Monnet <quentin@isovalent.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20210729162028.29512-9-quentin@isovalent.com --- tools/bpf/bpftool/btf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 9162a18e84c0..0ce3643278d4 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -580,7 +580,7 @@ static int do_dump(int argc, char **argv) } if (!btf) { - btf = btf__load_from_kernel_by_id(btf_id); + btf = btf__load_from_kernel_by_id_split(btf_id, base_btf); err = libbpf_get_error(btf); if (err) { p_err("get btf by id (%u): %s", btf_id, strerror(err)); -- cgit v1.2.3