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| author | Hengqi Chen <hengqi.chen@gmail.com> | 2023-09-29 15:59:54 +0000 |
|---|---|---|
| committer | Andrii Nakryiko <andrii.nakryiko@gmail.com> | 2023-10-02 11:17:48 -0700 |
| commit | 9a3a2e930319d64cfc1a629faa557c6cb4464c54 (patch) | |
| tree | 06b500bd81693bea8a277455bf98b59eb8c3e43f | |
| parent | 96d70a52adde3eed07673ecdc6ce3b8953071218 (diff) | |
| download | libbpf-9a3a2e930319d64cfc1a629faa557c6cb4464c54.tar.gz | |
libbpf: Allow Golang symbols in uprobe secdef
Golang symbols in ELF files are different from C/C++
which contains special characters like '*', '(' and ')'.
With generics, things get more complicated, there are
symbols like:
github.com/cilium/ebpf/internal.(*Deque[go.shape.interface { Format(fmt.State, int32); TypeName() string;github.com/cilium/ebpf/btf.copy() github.com/cilium/ebpf/btf.Type}]).Grow
Matching such symbols using `%m[^\n]` in sscanf, this
excludes newline which typically does not appear in ELF
symbols. This should work in most use-cases and also
work for unicode letters in identifiers. If newline do
show up in ELF symbols, users can still attach to such
symbol by specifying bpf_uprobe_opts::func_name.
A working example can be found at this repo ([0]).
[0]: https://github.com/chenhengqi/libbpf-go-symbols
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230929155954.92448-1-hengqi.chen@gmail.com
| -rw-r--r-- | src/libbpf.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/src/libbpf.c b/src/libbpf.c index b4758e5..31b8b25 100644 --- a/src/libbpf.c +++ b/src/libbpf.c @@ -11114,7 +11114,7 @@ static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, stru *link = NULL; - n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%ms", + n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%m[^\n]", &probe_type, &binary_path, &func_name); switch (n) { case 1: @@ -11624,14 +11624,14 @@ err_out: static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf_link **link) { DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, opts); - char *probe_type = NULL, *binary_path = NULL, *func_name = NULL; - int n, ret = -EINVAL; + char *probe_type = NULL, *binary_path = NULL, *func_name = NULL, *func_off; + int n, c, ret = -EINVAL; long offset = 0; *link = NULL; - n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%m[a-zA-Z0-9_.@]+%li", - &probe_type, &binary_path, &func_name, &offset); + n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%m[^\n]", + &probe_type, &binary_path, &func_name); switch (n) { case 1: /* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */ @@ -11642,7 +11642,17 @@ static int attach_uprobe(const struct bpf_program *prog, long cookie, struct bpf prog->name, prog->sec_name); break; case 3: - case 4: + /* check if user specifies `+offset`, if yes, this should be + * the last part of the string, make sure sscanf read to EOL + */ + func_off = strrchr(func_name, '+'); + if (func_off) { + n = sscanf(func_off, "+%li%n", &offset, &c); + if (n == 1 && *(func_off + c) == '\0') + func_off[0] = '\0'; + else + offset = 0; + } opts.retprobe = strcmp(probe_type, "uretprobe") == 0 || strcmp(probe_type, "uretprobe.s") == 0; if (opts.retprobe && offset != 0) { |