Yonghong Song 32337c0a28 bpf: Prevent inlining of bpf_fentry_test7() ... With latest clang18, I hit test_progs failures for the following test: #13/2 bpf_cookie/multi_kprobe_link_api:FAIL #13/3 bpf_cookie/multi_kprobe_attach_api:FAIL #13 bpf_cookie:FAIL #75 fentry_fexit:FAIL #76/1 fentry_test/fentry:FAIL #76 fentry_test:FAIL #80/1 fexit_test/fexit:FAIL #80 fexit_test:FAIL #110/1 kprobe_multi_test/skel_api:FAIL #110/2 kprobe_multi_test/link_api_addrs:FAIL #110/3 kprobe_multi_test/link_api_syms:FAIL #110/4 kprobe_multi_test/attach_api_pattern:FAIL #110/5 kprobe_multi_test/attach_api_addrs:FAIL #110/6 kprobe_multi_test/attach_api_syms:FAIL #110 kprobe_multi_test:FAIL For example, for #13/2, the error messages are: [...] kprobe_multi_test_run:FAIL:kprobe_test7_result unexpected kprobe_test7_result: actual 0 != expected 1 [...] kprobe_multi_test_run:FAIL:kretprobe_test7_result unexpected kretprobe_test7_result: actual 0 != expected 1 clang17 does not have this issue. Further investigation shows that kernel func bpf_fentry_test7(), used in the above tests, is inlined by the compiler although it is marked as noinline. int noinline bpf_fentry_test7(struct bpf_fentry_test_t *arg) { return (long)arg; } It is known that for simple functions like the above (e.g. just returning a constant or an input argument), the clang compiler may still do inlining for a noinline function. Adding 'asm volatile ("")' in the beginning of the bpf_fentry_test7() can prevent inlining. Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20230826200843.2210074-1-yonghong.song@linux.dev		2023-08-30 08:36:17 +02:00
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bpf_dummy_struct_ops.c	bpf: Remove unused arguments from btf_struct_access().	2023-04-04 16:57:10 -07:00
Makefile	bpf: Add dummy BPF STRUCT_OPS for test purpose	2021-11-01 14:10:00 -07:00
test_run.c	bpf: Prevent inlining of bpf_fentry_test7()	2023-08-30 08:36:17 +02:00