Message ID | 20230524084154.89226-1-liu.yun@linux.dev (mailing list archive) |
---|---|
State | Superseded |
Delegated to: | BPF |
Headers | show |
Series | [v3] libbpf: kprobe.multi: Filter with available_filter_functions | expand |
Context | Check | Description |
---|---|---|
bpf/vmtest-bpf-next-PR | success | PR summary |
netdev/tree_selection | success | Not a local patch |
bpf/vmtest-bpf-next-VM_Test-1 | success | Logs for ShellCheck |
bpf/vmtest-bpf-next-VM_Test-6 | success | Logs for set-matrix |
bpf/vmtest-bpf-next-VM_Test-2 | success | Logs for build for aarch64 with gcc |
bpf/vmtest-bpf-next-VM_Test-4 | success | Logs for build for x86_64 with gcc |
bpf/vmtest-bpf-next-VM_Test-5 | success | Logs for build for x86_64 with llvm-16 |
bpf/vmtest-bpf-next-VM_Test-3 | success | Logs for build for s390x with gcc |
bpf/vmtest-bpf-next-VM_Test-7 | success | Logs for test_maps on aarch64 with gcc |
bpf/vmtest-bpf-next-VM_Test-9 | success | Logs for test_maps on x86_64 with gcc |
bpf/vmtest-bpf-next-VM_Test-10 | success | Logs for test_maps on x86_64 with llvm-16 |
bpf/vmtest-bpf-next-VM_Test-19 | success | Logs for test_progs_no_alu32_parallel on aarch64 with gcc |
bpf/vmtest-bpf-next-VM_Test-20 | success | Logs for test_progs_no_alu32_parallel on x86_64 with gcc |
bpf/vmtest-bpf-next-VM_Test-21 | success | Logs for test_progs_no_alu32_parallel on x86_64 with llvm-16 |
bpf/vmtest-bpf-next-VM_Test-22 | success | Logs for test_progs_parallel on aarch64 with gcc |
bpf/vmtest-bpf-next-VM_Test-23 | success | Logs for test_progs_parallel on x86_64 with gcc |
bpf/vmtest-bpf-next-VM_Test-24 | success | Logs for test_progs_parallel on x86_64 with llvm-16 |
bpf/vmtest-bpf-next-VM_Test-25 | success | Logs for test_verifier on aarch64 with gcc |
bpf/vmtest-bpf-next-VM_Test-27 | success | Logs for test_verifier on x86_64 with gcc |
bpf/vmtest-bpf-next-VM_Test-28 | success | Logs for test_verifier on x86_64 with llvm-16 |
bpf/vmtest-bpf-next-VM_Test-29 | success | Logs for veristat |
bpf/vmtest-bpf-next-VM_Test-11 | success | Logs for test_progs on aarch64 with gcc |
bpf/vmtest-bpf-next-VM_Test-13 | success | Logs for test_progs on x86_64 with gcc |
bpf/vmtest-bpf-next-VM_Test-14 | success | Logs for test_progs on x86_64 with llvm-16 |
bpf/vmtest-bpf-next-VM_Test-15 | success | Logs for test_progs_no_alu32 on aarch64 with gcc |
bpf/vmtest-bpf-next-VM_Test-17 | success | Logs for test_progs_no_alu32 on x86_64 with gcc |
bpf/vmtest-bpf-next-VM_Test-18 | success | Logs for test_progs_no_alu32 on x86_64 with llvm-16 |
bpf/vmtest-bpf-next-VM_Test-26 | success | Logs for test_verifier on s390x with gcc |
bpf/vmtest-bpf-next-VM_Test-12 | success | Logs for test_progs on s390x with gcc |
bpf/vmtest-bpf-next-VM_Test-16 | success | Logs for test_progs_no_alu32 on s390x with gcc |
bpf/vmtest-bpf-next-VM_Test-8 | success | Logs for test_maps on s390x with gcc |
On Wed, May 24, 2023 at 04:41:54PM +0800, Jackie Liu wrote: > From: Jackie Liu <liuyun01@kylinos.cn> > > When using regular expression matching with "kprobe multi", it scans all > the functions under "/proc/kallsyms" that can be matched. However, not all > of them can be traced by kprobe.multi. If any one of the functions fails > to be traced, it will result in the failure of all functions. The best > approach is to filter out the functions that cannot be traced to ensure > proper tracking of the functions. > > Use available_filter_functions check first, if failed, fallback to > kallsyms. > > Here is the test eBPF program [1]. > [1] https://github.com/JackieLiu1/ketones/commit/a9e76d1ba57390e533b8b3eadde97f7a4535e867 > > Signed-off-by: Jackie Liu <liuyun01@kylinos.cn> > --- > v1: 0.27s user 5.09s system 99% cpu 5.392 total > v2: 0.37s user 1.54s system 98% cpu 1.947 total > v3: 0.10s user 0.98s system 97% cpu 1.107 total > > I saw that reading available_filter_functions takes 0.98s and kallsyms only > takes 0.12s. There is a big difference in performance between them. > > tools/lib/bpf/libbpf.c | 80 ++++++++++++++++++++++++++++++--- > tools/lib/bpf/libbpf_internal.h | 4 +- > 2 files changed, 77 insertions(+), 7 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index ad1ec893b41b..f3e3c92bdf8a 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -10417,13 +10417,14 @@ static bool glob_match(const char *str, const char *pat) > struct kprobe_multi_resolve { > const char *pattern; > unsigned long *addrs; > + const char **syms; > size_t cap; > size_t cnt; > }; > > static int > -resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, > - const char *sym_name, void *ctx) > +kallsyms_resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, > + const char *sym_name, void *ctx) > { > struct kprobe_multi_resolve *res = ctx; > int err; > @@ -10440,6 +10441,69 @@ resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, > return 0; > } > > +static int resolve_kprobe_multi_cb(const char *sym_name, void *ctx) > +{ > + struct kprobe_multi_resolve *res = ctx; > + int err; > + > + if (!glob_match(sym_name, res->pattern)) > + return 0; > + > + err = libbpf_ensure_mem((void **) &res->syms, &res->cap, sizeof(const char *), > + res->cnt + 1); > + if (err) > + return err; > + > + res->syms[res->cnt++] = strdup(sym_name); we need to check the strdup return value > + return 0; > +} > + > +int libbpf_available_filter_functions_parse(available_filter_functions_cb_t cb, > + void *ctx) might be too long, maybe we could just use 'ftrace' instead, so we'd have: libbpf_ftrace_parse libbpf_kallsyms_parse that might be too terse, but AFAIK we don't parse any other ftrace file > +{ > + char sym_name[256]; > + FILE *f; > + int ret, err = 0; > + > + f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r"); > + if (!f) { > + pr_warn("failed to open available_filter_functions, fallback to /proc/kallsyms.\n"); > + goto fallback; > + } > + > + while (true) { > + ret = fscanf(f, "%s%*[^\n]\n", sym_name); > + if (ret == EOF && feof(f)) > + break; > + if (ret != 1) { > + pr_warn("failed to read available_filter_functions entry: %d\n", > + ret); > + break; > + } > + > + err = cb(sym_name, ctx); > + if (err) > + break; > + } > + > + fclose(f); > + return err; > + > +fallback: > + return libbpf_kallsyms_parse(kallsyms_resolve_kprobe_multi_cb, ctx); let's do the kallsyms fallback in bpf_program__attach_kprobe_multi_opts, something like: err = libbpf_available_filter_functions_parse(resolve_kprobe_multi_cb, &res); if (err) err = libbpf_kallsyms_parse(kallsyms_resolve_kprobe_multi_cb, &res); if (err) goto error; > +} > + > +static void kprobe_multi_resolve_resource_free(struct kprobe_multi_resolve *res) s/kprobe_multi_resolve_resource_free/kprobe_multi_resolve_free/ > +{ > + if (res->syms) { > + while (res->cnt) > + free((char *)res->syms[--res->cnt]); > + free(res->syms); > + } else { > + free(res->addrs); > + } > +} > + > struct bpf_link * > bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, > const char *pattern, > @@ -10476,14 +10540,18 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, > return libbpf_err_ptr(-EINVAL); > > if (pattern) { > - err = libbpf_kallsyms_parse(resolve_kprobe_multi_cb, &res); > + err = libbpf_available_filter_functions_parse(resolve_kprobe_multi_cb, > + &res); > if (err) > goto error; > if (!res.cnt) { > err = -ENOENT; > goto error; > } > - addrs = res.addrs; > + if (res.syms) > + syms = res.syms; > + else > + addrs = res.addrs; this could be just: syms = res.syms; addrs = res.addrs; once (cnt > 0) then we have either syms or addrs defined and the other is NULL > cnt = res.cnt; > } > > @@ -10511,12 +10579,12 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, > goto error; > } > link->fd = link_fd; > - free(res.addrs); > + kprobe_multi_resolve_resource_free(&res); > return link; > > error: > free(link); > - free(res.addrs); > + kprobe_multi_resolve_resource_free(&res); > return libbpf_err_ptr(err); > } > > diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h > index e4d05662a96c..fdf6b464481f 100644 > --- a/tools/lib/bpf/libbpf_internal.h > +++ b/tools/lib/bpf/libbpf_internal.h > @@ -481,8 +481,10 @@ __s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name, > > typedef int (*kallsyms_cb_t)(unsigned long long sym_addr, char sym_type, > const char *sym_name, void *ctx); > - > int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *arg); > +typedef int (*available_filter_functions_cb_t)(const char *sym_name, void *ctx); > +int libbpf_available_filter_functions_parse(available_filter_functions_cb_t cb, > + void *arg); let's kee it static, we don't have any other callers thanks, jirka
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index ad1ec893b41b..f3e3c92bdf8a 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10417,13 +10417,14 @@ static bool glob_match(const char *str, const char *pat) struct kprobe_multi_resolve { const char *pattern; unsigned long *addrs; + const char **syms; size_t cap; size_t cnt; }; static int -resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, - const char *sym_name, void *ctx) +kallsyms_resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, + const char *sym_name, void *ctx) { struct kprobe_multi_resolve *res = ctx; int err; @@ -10440,6 +10441,69 @@ resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, return 0; } +static int resolve_kprobe_multi_cb(const char *sym_name, void *ctx) +{ + struct kprobe_multi_resolve *res = ctx; + int err; + + if (!glob_match(sym_name, res->pattern)) + return 0; + + err = libbpf_ensure_mem((void **) &res->syms, &res->cap, sizeof(const char *), + res->cnt + 1); + if (err) + return err; + + res->syms[res->cnt++] = strdup(sym_name); + return 0; +} + +int libbpf_available_filter_functions_parse(available_filter_functions_cb_t cb, + void *ctx) +{ + char sym_name[256]; + FILE *f; + int ret, err = 0; + + f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r"); + if (!f) { + pr_warn("failed to open available_filter_functions, fallback to /proc/kallsyms.\n"); + goto fallback; + } + + while (true) { + ret = fscanf(f, "%s%*[^\n]\n", sym_name); + if (ret == EOF && feof(f)) + break; + if (ret != 1) { + pr_warn("failed to read available_filter_functions entry: %d\n", + ret); + break; + } + + err = cb(sym_name, ctx); + if (err) + break; + } + + fclose(f); + return err; + +fallback: + return libbpf_kallsyms_parse(kallsyms_resolve_kprobe_multi_cb, ctx); +} + +static void kprobe_multi_resolve_resource_free(struct kprobe_multi_resolve *res) +{ + if (res->syms) { + while (res->cnt) + free((char *)res->syms[--res->cnt]); + free(res->syms); + } else { + free(res->addrs); + } +} + struct bpf_link * bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, const char *pattern, @@ -10476,14 +10540,18 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, return libbpf_err_ptr(-EINVAL); if (pattern) { - err = libbpf_kallsyms_parse(resolve_kprobe_multi_cb, &res); + err = libbpf_available_filter_functions_parse(resolve_kprobe_multi_cb, + &res); if (err) goto error; if (!res.cnt) { err = -ENOENT; goto error; } - addrs = res.addrs; + if (res.syms) + syms = res.syms; + else + addrs = res.addrs; cnt = res.cnt; } @@ -10511,12 +10579,12 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, goto error; } link->fd = link_fd; - free(res.addrs); + kprobe_multi_resolve_resource_free(&res); return link; error: free(link); - free(res.addrs); + kprobe_multi_resolve_resource_free(&res); return libbpf_err_ptr(err); } diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index e4d05662a96c..fdf6b464481f 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -481,8 +481,10 @@ __s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name, typedef int (*kallsyms_cb_t)(unsigned long long sym_addr, char sym_type, const char *sym_name, void *ctx); - int libbpf_kallsyms_parse(kallsyms_cb_t cb, void *arg); +typedef int (*available_filter_functions_cb_t)(const char *sym_name, void *ctx); +int libbpf_available_filter_functions_parse(available_filter_functions_cb_t cb, + void *arg); /* handle direct returned errors */ static inline int libbpf_err(int ret)