Merge branch 'Attach a cookie to a tracing program.'

Kui-Feng Lee says:

====================

Allow users to attach a 64-bits cookie to a bpf_link of fentry, fexit,
or fmod_ret.

This patchset includes several major changes.

 - Define struct bpf_tramp_links to replace bpf_tramp_prog.
   struct bpf_tramp_links collects bpf_links of a trampoline

 - Generate a trampoline to call bpf_progs of given bpf_links.

 - Trampolines always set/reset bpf_run_ctx before/after
   calling/leaving a tracing program.

 - Attach a cookie to a bpf_link of fentry/fexit/fmod_ret/lsm.  The
   value will be available when running the associated bpf_prog.

Th major differences from v6:

 - bpf_link_create() can create links of BPF_LSM_MAC attach type.

 - Add a test for lsm.

 - Add function proto of bpf_get_attach_cookie() for lsm.

 - Check BPF_LSM_MAC in bpf_prog_has_trampoline().

 - Adapt to the changes of LINK_CREATE made by Andrii.

The major differences from v7:

 - Change stack_size instead of pushing/popping run_ctx.

 - Move cookie to bpf_tramp_link from bpf_tracing_link..

v1: https://lore.kernel.org/all/20220126214809.3868787-1-kuifeng@fb.com/
v2: https://lore.kernel.org/bpf/20220316004231.1103318-1-kuifeng@fb.com/
v3: https://lore.kernel.org/bpf/20220407192552.2343076-1-kuifeng@fb.com/
v4: https://lore.kernel.org/bpf/20220411173429.4139609-1-kuifeng@fb.com/
v5: https://lore.kernel.org/bpf/20220412165555.4146407-1-kuifeng@fb.com/
v6: https://lore.kernel.org/bpf/20220416042940.656344-1-kuifeng@fb.com/
v7: https://lore.kernel.org/bpf/20220508032117.2783209-1-kuifeng@fb.com/
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

1 files changed, 16 insertions, 4 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 15117b9a4d1e..a5904c0ac794 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11568,12 +11568,17 @@ static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf
 }
 
 /* Common logic for all BPF program types that attach to a btf_id */
-static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog)
+static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *prog,
+						   const struct bpf_trace_opts *opts)
 {
+	LIBBPF_OPTS(bpf_link_create_opts, link_opts);
 	char errmsg[STRERR_BUFSIZE];
 	struct bpf_link *link;
 	int prog_fd, pfd;
 
+	if (!OPTS_VALID(opts, bpf_trace_opts))
+		return libbpf_err_ptr(-EINVAL);
+
 	prog_fd = bpf_program__fd(prog);
 	if (prog_fd < 0) {
 		pr_warn("prog '%s': can't attach before loaded\n", prog->name);
@@ -11586,7 +11591,8 @@ static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *pro
 	link->detach = &bpf_link__detach_fd;
 
 	/* libbpf is smart enough to redirect to BPF_RAW_TRACEPOINT_OPEN on old kernels */
-	pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), NULL);
+	link_opts.tracing.cookie = OPTS_GET(opts, cookie, 0);
+	pfd = bpf_link_create(prog_fd, 0, bpf_program__expected_attach_type(prog), &link_opts);
 	if (pfd < 0) {
 		pfd = -errno;
 		free(link);
@@ -11600,12 +11606,18 @@ static struct bpf_link *bpf_program__attach_btf_id(const struct bpf_program *pro
 
 struct bpf_link *bpf_program__attach_trace(const struct bpf_program *prog)
 {
-	return bpf_program__attach_btf_id(prog);
+	return bpf_program__attach_btf_id(prog, NULL);
+}
+
+struct bpf_link *bpf_program__attach_trace_opts(const struct bpf_program *prog,
+						const struct bpf_trace_opts *opts)
+{
+	return bpf_program__attach_btf_id(prog, opts);
 }
 
 struct bpf_link *bpf_program__attach_lsm(const struct bpf_program *prog)
 {
-	return bpf_program__attach_btf_id(prog);
+	return bpf_program__attach_btf_id(prog, NULL);
 }
 
 static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link)