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| author | Yonghong Song <yonghong.song@linux.dev> | 2023-11-27 06:03:42 +0100 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2023-11-27 14:53:39 +0100 |
| commit | b16904fd9f01b580db357ef2b1cc9e86d89576c2 (patch) | |
| tree | d09f1e29a712d5b694f206b2b6023fe2fbe1dc34 /net/bpf | |
| parent | selftests/bpf: Add lazy global subprog validation tests (diff) | |
| download | linux-b16904fd9f01b580db357ef2b1cc9e86d89576c2.tar.xz linux-b16904fd9f01b580db357ef2b1cc9e86d89576c2.zip | |
bpf: Fix a few selftest failures due to llvm18 change
With latest upstream llvm18, the following test cases failed:
$ ./test_progs -j
#13/2 bpf_cookie/multi_kprobe_link_api:FAIL
#13/3 bpf_cookie/multi_kprobe_attach_api:FAIL
#13 bpf_cookie:FAIL
#77 fentry_fexit:FAIL
#78/1 fentry_test/fentry:FAIL
#78 fentry_test:FAIL
#82/1 fexit_test/fexit:FAIL
#82 fexit_test:FAIL
#112/1 kprobe_multi_test/skel_api:FAIL
#112/2 kprobe_multi_test/link_api_addrs:FAIL
[...]
#112 kprobe_multi_test:FAIL
#356/17 test_global_funcs/global_func17:FAIL
#356 test_global_funcs:FAIL
Further analysis shows llvm upstream patch [1] is responsible for the above
failures. For example, for function bpf_fentry_test7() in net/bpf/test_run.c,
without [1], the asm code is:
0000000000000400 <bpf_fentry_test7>:
400: f3 0f 1e fa endbr64
404: e8 00 00 00 00 callq 0x409 <bpf_fentry_test7+0x9>
409: 48 89 f8 movq %rdi, %rax
40c: c3 retq
40d: 0f 1f 00 nopl (%rax)
... and with [1], the asm code is:
0000000000005d20 <bpf_fentry_test7.specialized.1>:
5d20: e8 00 00 00 00 callq 0x5d25 <bpf_fentry_test7.specialized.1+0x5>
5d25: c3 retq
... and <bpf_fentry_test7.specialized.1> is called instead of <bpf_fentry_test7>
and this caused test failures for #13/#77 etc. except #356.
For test case #356/17, with [1] (progs/test_global_func17.c)), the main prog
looks like:
0000000000000000 <global_func17>:
0: b4 00 00 00 2a 00 00 00 w0 = 0x2a
1: 95 00 00 00 00 00 00 00 exit
... which passed verification while the test itself expects a verification
failure.
Let us add 'barrier_var' style asm code in both places to prevent function
specialization which caused selftests failure.
[1] https://github.com/llvm/llvm-project/pull/72903
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231127050342.1945270-1-yonghong.song@linux.dev
Diffstat (limited to 'net/bpf')
| -rw-r--r-- | net/bpf/test_run.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index c9fdcc5cdce1..711cf5d59816 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -542,7 +542,7 @@ struct bpf_fentry_test_t { int noinline bpf_fentry_test7(struct bpf_fentry_test_t *arg) { - asm volatile (""); + asm volatile ("": "+r"(arg)); return (long)arg; } |