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selftests/bpf: Test re-attachment fix for bpf_tracing_prog_attach

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Add a test case to verify the fix for "prog->aux->dst_trampoline and
tgt_prog is NULL" branch in bpf_tracing_prog_attach. The sequence of
events:

1. load rawtp program
2. load fentry program with rawtp as target_fd
3. create tracing link for fentry program with target_fd = 0
4. repeat 3

Acked-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
Link: https://lore.kernel.org/r/20240103190559.14750-5-9erthalion6@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Dmitrii Dolgov 2024-01-03 20:05:47 +01:00 committed by Alexei Starovoitov
parent 715d82ba63
commit e02feb3f1f
2 changed files with 53 additions and 0 deletions
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44
tools/testing/selftests/bpf/prog_tests/recursive_attach.c
View file

@ -105,3 +105,47 @@ void test_recursive_fentry(void)
if (test__start_subtest("detach"))
test_recursive_fentry_chain(true, true);
}
/* Test that a tracing prog reattachment (when we land in
* "prog->aux->dst_trampoline and tgt_prog is NULL" branch in
* bpf_tracing_prog_attach) does not lead to a crash due to missing attach_btf
*/
void test_fentry_attach_btf_presence(void)
{
struct fentry_recursive_target *target_skel = NULL;
struct fentry_recursive *tracing_skel = NULL;
struct bpf_program *prog;
int err, link_fd, tgt_prog_fd;
target_skel = fentry_recursive_target__open_and_load();
if (!ASSERT_OK_PTR(target_skel, "fentry_recursive_target__open_and_load"))
goto close_prog;
tracing_skel = fentry_recursive__open();
if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open"))
goto close_prog;
prog = tracing_skel->progs.recursive_attach;
tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target);
err = bpf_program__set_attach_target(prog, tgt_prog_fd, "fentry_target");
if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
goto close_prog;
err = fentry_recursive__load(tracing_skel);
if (!ASSERT_OK(err, "fentry_recursive__load"))
goto close_prog;
tgt_prog_fd = bpf_program__fd(tracing_skel->progs.recursive_attach);
link_fd = bpf_link_create(tgt_prog_fd, 0, BPF_TRACE_FENTRY, NULL);
if (!ASSERT_GE(link_fd, 0, "link_fd"))
goto close_prog;
fentry_recursive__detach(tracing_skel);
err = fentry_recursive__attach(tracing_skel);
ASSERT_ERR(err, "fentry_recursive__attach");
close_prog:
fentry_recursive_target__destroy(target_skel);
fentry_recursive__destroy(tracing_skel);
}

9
tools/testing/selftests/bpf/progs/fentry_recursive_target.c
View file

@ -14,3 +14,12 @@ int BPF_PROG(test1, int a)
{
return 0;
}
/* Dummy bpf prog for testing attach_btf presence when attaching an fentry
* program.
*/
SEC("raw_tp/sys_enter")
int BPF_PROG(fentry_target, struct pt_regs *regs, long id)
{
return 0;
}