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author | 2023-08-09 10:34:28 +0200 | |
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committer | 2023-08-21 15:51:26 -0700 | |
commit | 7e1b468123453bbb047eab7c7d6cecd4dd318ff0 (patch) | |
tree | b7cd04b61a9cea19797f1ca83a1148cd278b2d33 /tools/lib | |
parent | libbpf: Add support for u[ret]probe.multi[.s] program sections (diff) | |
download | linux-7e1b468123453bbb047eab7c7d6cecd4dd318ff0.tar.gz linux-7e1b468123453bbb047eab7c7d6cecd4dd318ff0.tar.bz2 linux-7e1b468123453bbb047eab7c7d6cecd4dd318ff0.zip |
libbpf: Add uprobe multi link detection
Adding uprobe-multi link detection. It will be used later in
bpf_program__attach_usdt function to check and use uprobe_multi
link over standard uprobe links.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-17-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/lib')
-rw-r--r-- | tools/lib/bpf/libbpf.c | 36 | ||||
-rw-r--r-- | tools/lib/bpf/libbpf_internal.h | 2 |
2 files changed, 38 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index c9c390542040..07b6cbe70059 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -4829,6 +4829,39 @@ static int probe_perf_link(void) return link_fd < 0 && err == -EBADF; } +static int probe_uprobe_multi_link(void) +{ + LIBBPF_OPTS(bpf_prog_load_opts, load_opts, + .expected_attach_type = BPF_TRACE_UPROBE_MULTI, + ); + LIBBPF_OPTS(bpf_link_create_opts, link_opts); + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int prog_fd, link_fd, err; + unsigned long offset = 0; + + prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", + insns, ARRAY_SIZE(insns), &load_opts); + if (prog_fd < 0) + return -errno; + + /* Creating uprobe in '/' binary should fail with -EBADF. */ + link_opts.uprobe_multi.path = "/"; + link_opts.uprobe_multi.offsets = &offset; + link_opts.uprobe_multi.cnt = 1; + + link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, &link_opts); + err = -errno; /* close() can clobber errno */ + + if (link_fd >= 0) + close(link_fd); + close(prog_fd); + + return link_fd < 0 && err == -EBADF; +} + static int probe_kern_bpf_cookie(void) { struct bpf_insn insns[] = { @@ -4925,6 +4958,9 @@ static struct kern_feature_desc { [FEAT_SYSCALL_WRAPPER] = { "Kernel using syscall wrapper", probe_kern_syscall_wrapper, }, + [FEAT_UPROBE_MULTI_LINK] = { + "BPF multi-uprobe link support", probe_uprobe_multi_link, + }, }; bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id) diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index ead551318fec..f0f08635adb0 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -355,6 +355,8 @@ enum kern_feature_id { FEAT_BTF_ENUM64, /* Kernel uses syscall wrapper (CONFIG_ARCH_HAS_SYSCALL_WRAPPER) */ FEAT_SYSCALL_WRAPPER, + /* BPF multi-uprobe link support */ + FEAT_UPROBE_MULTI_LINK, __FEAT_CNT, }; |