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| author |   Jiri Olsa <jolsa@kernel.org> | 2022-07-14 10:23:16 +0200 |
|---|---|---|
| committer |   Andrii Nakryiko <andrii@kernel.org> | 2022-07-14 22:34:46 -0700 |
| commit | 7fb27a56b9ebd8a77d9dd188e8a42bff99bc3443 (patch) | |
| tree | 472007772458774b3ac0054680be1fc588123ff8 | |
| parent | bpf: Add endian modifiers to fix endian warnings (diff) | |
| download | linux-dev-7fb27a56b9ebd8a77d9dd188e8a42bff99bc3443.tar.xz linux-dev-7fb27a56b9ebd8a77d9dd188e8a42bff99bc3443.zip | |
selftests/bpf: Do not attach kprobe_multi bench to bpf_dispatcher_xdp_func
Alexei reported crash by running test_progs -j on system
with 32 cpus.
It turned out the kprobe_multi bench test that attaches all
ftrace-able functions will race with bpf_dispatcher_update,
that calls bpf_arch_text_poke on bpf_dispatcher_xdp_func,
which is ftrace-able function.
Ftrace is not aware of this update so this will cause
ftrace_bug with:
WARNING: CPU: 6 PID: 1985 at
arch/x86/kernel/ftrace.c:94 ftrace_verify_code+0x27/0x50
...
ftrace_replace_code+0xa3/0x170
ftrace_modify_all_code+0xbd/0x150
ftrace_startup_enable+0x3f/0x50
ftrace_startup+0x98/0xf0
register_ftrace_function+0x20/0x60
register_fprobe_ips+0xbb/0xd0
bpf_kprobe_multi_link_attach+0x179/0x430
__sys_bpf+0x18a1/0x2440
...
------------[ ftrace bug ]------------
ftrace failed to modify
[<ffffffff818d9380>] bpf_dispatcher_xdp_func+0x0/0x10
actual: ffffffe9:7b:ffffff9c:77:1e
Setting ftrace call site to call ftrace function
It looks like we need some way to hide some functions
from ftrace, but meanwhile we workaround this by skipping
bpf_dispatcher_xdp_func from kprobe_multi bench test.
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220714082316.479181-1-jolsa@kernel.org
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c | 2 |
1 files changed, 2 insertions, 0 deletions
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 335917df0614..d457a55ff408 100644 --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c @@ -364,6 +364,8 @@ static int get_syms(char ***symsp, size_t *cntp) continue; if (!strncmp(name, "rcu_", 4)) continue; + if (!strcmp(name, "bpf_dispatcher_xdp_func")) + continue; if (!strncmp(name, "__ftrace_invalid_address__", sizeof("__ftrace_invalid_address__") - 1)) continue; |