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authorYonghong Song <yonghong.song@linux.dev>2023-11-26 21:03:42 -0800
committerDaniel Borkmann <daniel@iogearbox.net>2023-11-27 14:53:39 +0100
commitb16904fd9f01b580db357ef2b1cc9e86d89576c2 (patch)
treed09f1e29a712d5b694f206b2b6023fe2fbe1dc34
parente8a339b5235e294f29153149ea7cf26a9a87dbea (diff)
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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
-rw-r--r--net/bpf/test_run.c2
-rw-r--r--tools/testing/selftests/bpf/progs/test_global_func17.c1
2 files changed, 2 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;
}
diff --git a/tools/testing/selftests/bpf/progs/test_global_func17.c b/tools/testing/selftests/bpf/progs/test_global_func17.c
index a32e11c7d933..5de44b09e8ec 100644
--- a/tools/testing/selftests/bpf/progs/test_global_func17.c
+++ b/tools/testing/selftests/bpf/progs/test_global_func17.c
@@ -5,6 +5,7 @@
__noinline int foo(int *p)
{
+ barrier_var(p);
return p ? (*p = 42) : 0;
}