Re: [PATCH bpf-next v4 2/3] libbpf: support detecting and attaching of writable tracepoint program
From: Andrii Nakryiko <hidden>
Date: 2021-10-01 22:21:17
Also in:
bpf
On Thu, Sep 30, 2021 at 2:00 AM Hou Tao [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Program on writable tracepoint is BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE, but its attachment is the same as BPF_PROG_TYPE_RAW_TRACEPOINT. Signed-off-by: Hou Tao <redacted> --- tools/lib/bpf/libbpf.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 7544d7d09160..80faa53dff35 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c@@ -8005,6 +8005,8 @@ static const struct bpf_sec_def section_defs[] = { SEC_DEF("tp/", TRACEPOINT, 0, SEC_NONE, attach_tp), SEC_DEF("raw_tracepoint/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp), SEC_DEF("raw_tp/", RAW_TRACEPOINT, 0, SEC_NONE, attach_raw_tp), + SEC_DEF("raw_tracepoint.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp), + SEC_DEF("raw_tp.w/", RAW_TRACEPOINT_WRITABLE, 0, SEC_NONE, attach_raw_tp), SEC_DEF("tp_btf/", TRACING, BPF_TRACE_RAW_TP, SEC_ATTACH_BTF, attach_trace), SEC_DEF("fentry/", TRACING, BPF_TRACE_FENTRY, SEC_ATTACH_BTF, attach_trace), SEC_DEF("fmod_ret/", TRACING, BPF_MODIFY_RETURN, SEC_ATTACH_BTF, attach_trace),@@ -9762,12 +9764,21 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(const struct bpf_program *pr static struct bpf_link *attach_raw_tp(const struct bpf_program *prog, long cookie) { - const char *tp_name; + static const char *prefixes[] = { + "raw_tp/", + "raw_tracepoint/", + "raw_tp.w/", + "raw_tracepoint.w/", + }; + size_t i; + const char *tp_name = NULL; - if (str_has_pfx(prog->sec_name, "raw_tp/")) - tp_name = prog->sec_name + sizeof("raw_tp/") - 1; - else - tp_name = prog->sec_name + sizeof("raw_tracepoint/") - 1; + for (i = 0; i < ARRAY_SIZE(prefixes); i++) { + if (str_has_pfx(prog->sec_name, prefixes[i])) { + tp_name = prog->sec_name + strlen(prefixes[i]); + break; + } + }
Let's add if (!tp_name) check here for the future if we forget to update this prefixes list. It's going to be a really unpleasant SIGSEGV otherwise.
return bpf_program__attach_raw_tracepoint(prog, tp_name);
}
--
2.29.2