[PATCH bpf-next] selftests/bpf: Filter out preempt_count_ functions from kprobe_multi bench

[Yafang Shao <laoar.shao@gmail.com>]

It hits below warning on my test machine when running test_progs,

[  702.223611] ------------[ cut here ]------------
[  702.224168] RCU not on for: preempt_count_sub+0x0/0xa0
[  702.224770] WARNING: CPU: 14 PID: 5267 at include/linux/trace_recursion.h:162 fprobe_handler.part.0+0x1b8/0x1c0
[  702.231740] CPU: 14 PID: 5267 Comm: main_amd64 Kdump: loaded Tainted: G           O       6.2.0+ #584
[  702.233169] RIP: 0010:fprobe_handler.part.0+0x1b8/0x1c0
[  702.241388] Call Trace:
[  702.241615]  <TASK>
[  702.241811]  fprobe_handler+0x22/0x30
[  702.242129]  0xffffffffc04710f7
[  702.242417] RIP: 0010:preempt_count_sub+0x5/0xa0
[  702.242809] Code: c8 50 68 94 42 0e b5 48 cf e9 f9 fd ff ff 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 e8 4b cd 38 0b <55> 8b 0d 9c d0 cf 02 48 89 e5 85 c9 75 1b 65 8b 05 be 78 f4 4a 89
[  702.244752] RSP: 0018:ffffaf6187d27f10 EFLAGS: 00000082 ORIG_RAX: 0000000000000000
[  702.245801] RAX: 000000000000000e RBX: 0000000001b6ab72 RCX: 0000000000000000
[  702.246804] RDX: 0000000000000000 RSI: ffffffffb627967d RDI: 0000000000000001
[  702.247801] RBP: ffffaf6187d27f30 R08: 0000000000000000 R09: 0000000000000000
[  702.248786] R10: 0000000000000000 R11: 0000000000000000 R12: 00000000000000ca
[  702.249782] R13: ffffaf6187d27f58 R14: 0000000000000000 R15: 0000000000000000
[  702.250785]  ? preempt_count_sub+0x5/0xa0
[  702.251540]  ? syscall_enter_from_user_mode+0x96/0xc0
[  702.252368]  ? preempt_count_sub+0x5/0xa0
[  702.253104]  ? syscall_enter_from_user_mode+0x96/0xc0
[  702.253918]  do_syscall_64+0x16/0x90
[  702.254613]  entry_SYSCALL_64_after_hwframe+0x72/0xdc
[  702.255422] RIP: 0033:0x46b793

It's caused by bench test attaching kprobe_multi link to preempt_count_sub
function, which is not executed in rcu safe context so the kprobe handler
on top of it will trigger the rcu warning.

Filtering out preempt_count_ functions from the bench test.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
index 22be0a9..5561b93 100644
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -379,6 +379,8 @@ static int get_syms(char ***symsp, size_t *cntp, bool kernel)
 		if (!strncmp(name, "__ftrace_invalid_address__",
 			     sizeof("__ftrace_invalid_address__") - 1))
 			continue;
+		if (!strncmp(name, "preempt_count_", strlen("preempt_count_")))
+			continue;
 
 		err = hashmap__add(map, name, 0);
 		if (err == -EEXIST)
-- 
1.8.3.1