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[213.175.37.12]) by smtp.gmail.com with ESMTPSA id by22sm15763502ejb.5.2022.02.02.05.54.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Feb 2022 05:54:12 -0800 (PST) From: Jiri Olsa X-Google-Original-From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Masami Hiramatsu Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, lkml , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Steven Rostedt , Jiri Olsa Subject: [PATCH 6/8] libbpf: Add bpf_program__attach_kprobe_opts for multi kprobes Date: Wed, 2 Feb 2022 14:53:31 +0100 Message-Id: <20220202135333.190761-7-jolsa@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220202135333.190761-1-jolsa@kernel.org> References: <20220202135333.190761-1-jolsa@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Adding support to bpf_program__attach_kprobe_opts to load kprobes to multiple functions. If the kprobe program has BPF_TRACE_FPROBE as expected_attach_type it will use the new fprobe link to attach the program. In this case it will use 'func_name' as pattern for functions to attach. Adding also support to use '*' wildcard in 'kprobe/kretprobe' section name by SEC macro, like: SEC("kprobe/bpf_fentry_test*") SEC("kretprobe/bpf_fentry_test*") This will set kprobe's expected_attach_type to BPF_TRACE_FPROBE, and attach it to provided functions pattern. Signed-off-by: Jiri Olsa --- tools/lib/bpf/libbpf.c | 136 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 133 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 7d595cfd03bc..6b343ef77ed8 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -8607,13 +8607,15 @@ static struct bpf_link *attach_trace(const struct bpf_program *prog, long cookie static struct bpf_link *attach_lsm(const struct bpf_program *prog, long cookie); static struct bpf_link *attach_iter(const struct bpf_program *prog, long cookie); +static int init_kprobe(struct bpf_program *prog, long cookie); + static const struct bpf_sec_def section_defs[] = { SEC_DEF("socket", SOCKET_FILTER, 0, SEC_NONE | SEC_SLOPPY_PFX), SEC_DEF("sk_reuseport/migrate", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT_OR_MIGRATE, SEC_ATTACHABLE | SEC_SLOPPY_PFX), SEC_DEF("sk_reuseport", SK_REUSEPORT, BPF_SK_REUSEPORT_SELECT, SEC_ATTACHABLE | SEC_SLOPPY_PFX), - SEC_DEF("kprobe/", KPROBE, 0, SEC_NONE, attach_kprobe), + SEC_DEF("kprobe/", KPROBE, 0, SEC_NONE, attach_kprobe, .init_fn = init_kprobe), SEC_DEF("uprobe/", KPROBE, 0, SEC_NONE), - SEC_DEF("kretprobe/", KPROBE, 0, SEC_NONE, attach_kprobe), + SEC_DEF("kretprobe/", KPROBE, 0, SEC_NONE, attach_kprobe, .init_fn = init_kprobe), SEC_DEF("uretprobe/", KPROBE, 0, SEC_NONE), SEC_DEF("tc", SCHED_CLS, 0, SEC_NONE), SEC_DEF("classifier", SCHED_CLS, 0, SEC_NONE | SEC_SLOPPY_PFX | SEC_DEPRECATED), @@ -10031,6 +10033,123 @@ static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe, return pfd; } +struct fprobe_resolve { + const char *name; + __u64 *addrs; + __u32 alloc; + __u32 cnt; +}; + +static bool glob_matches(const char *glob, const char *s) +{ + int n = strlen(glob); + + if (n == 1 && glob[0] == '*') + return true; + + if (glob[0] == '*' && glob[n - 1] == '*') { + const char *subs; + /* substring match */ + + /* this is hacky, but we don't want to allocate + * for no good reason + */ + ((char *)glob)[n - 1] = '\0'; + subs = strstr(s, glob + 1); + ((char *)glob)[n - 1] = '*'; + + return subs != NULL; + } else if (glob[0] == '*') { + size_t nn = strlen(s); + /* suffix match */ + + /* too short for a given suffix */ + if (nn < n - 1) + return false; + return strcmp(s + nn - (n - 1), glob + 1) == 0; + } else if (glob[n - 1] == '*') { + /* prefix match */ + return strncmp(s, glob, n - 1) == 0; + } else { + /* exact match */ + return strcmp(glob, s) == 0; + } +} + +static int resolve_fprobe_cb(void *arg, unsigned long long sym_addr, + char sym_type, const char *sym_name) +{ + struct fprobe_resolve *res = arg; + __u64 *p; + + if (!glob_matches(res->name, sym_name)) + return 0; + + if (res->cnt == res->alloc) { + res->alloc = max((__u32) 16, res->alloc * 3 / 2); + p = libbpf_reallocarray(res->addrs, res->alloc, sizeof(__u32)); + if (!p) + return -ENOMEM; + res->addrs = p; + } + res->addrs[res->cnt++] = sym_addr; + return 0; +} + +static struct bpf_link * +attach_fprobe_opts(const struct bpf_program *prog, + const char *func_name, + const struct bpf_kprobe_opts *kopts) +{ + DECLARE_LIBBPF_OPTS(bpf_link_create_opts, opts); + struct fprobe_resolve res = { + .name = func_name, + }; + struct bpf_link *link = NULL; + char errmsg[STRERR_BUFSIZE]; + int err, link_fd, prog_fd; + bool retprobe; + + err = libbpf__kallsyms_parse(&res, resolve_fprobe_cb); + if (err) + goto error; + if (!res.cnt) { + err = -ENOENT; + goto error; + } + + retprobe = OPTS_GET(kopts, retprobe, false); + + opts.fprobe.addrs = (__u64) res.addrs; + opts.fprobe.cnt = res.cnt; + opts.flags = retprobe ? BPF_F_FPROBE_RETURN : 0; + + link = calloc(1, sizeof(*link)); + if (!link) { + err = -ENOMEM; + goto error; + } + link->detach = &bpf_link__detach_fd; + + prog_fd = bpf_program__fd(prog); + link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_FPROBE, &opts); + if (link_fd < 0) { + err = -errno; + pr_warn("prog '%s': failed to attach to %s: %s\n", + prog->name, res.name, + libbpf_strerror_r(err, errmsg, sizeof(errmsg))); + goto error; + } + link->fd = link_fd; + free(res.addrs); + return link; + +error: + free(link); + free(res.addrs); + return libbpf_err_ptr(err); +} + struct bpf_link * bpf_program__attach_kprobe_opts(const struct bpf_program *prog, const char *func_name, @@ -10047,6 +10166,9 @@ bpf_program__attach_kprobe_opts(const struct bpf_program *prog, if (!OPTS_VALID(opts, bpf_kprobe_opts)) return libbpf_err_ptr(-EINVAL); + if (prog->expected_attach_type == BPF_TRACE_FPROBE) + return attach_fprobe_opts(prog, func_name, opts); + retprobe = OPTS_GET(opts, retprobe, false); offset = OPTS_GET(opts, offset, 0); pe_opts.bpf_cookie = OPTS_GET(opts, bpf_cookie, 0); @@ -10112,6 +10234,14 @@ struct bpf_link *bpf_program__attach_kprobe(const struct bpf_program *prog, return bpf_program__attach_kprobe_opts(prog, func_name, &opts); } +static int init_kprobe(struct bpf_program *prog, long cookie) +{ + /* If we have wildcard, switch to fprobe link. */ + if (strchr(prog->sec_name, '*')) + bpf_program__set_expected_attach_type(prog, BPF_TRACE_FPROBE); + return 0; +} + static struct bpf_link *attach_kprobe(const struct bpf_program *prog, long cookie) { DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts); @@ -10127,7 +10257,7 @@ static struct bpf_link *attach_kprobe(const struct bpf_program *prog, long cooki else func_name = prog->sec_name + sizeof("kprobe/") - 1; - n = sscanf(func_name, "%m[a-zA-Z0-9_.]+%li", &func, &offset); + n = sscanf(func_name, "%m[a-zA-Z0-9_.*]+%li", &func, &offset); if (n < 1) { err = -EINVAL; pr_warn("kprobe name is invalid: %s\n", func_name); -- 2.34.1