Re: [PATCH bpf-next v1 3/7] selftests/bpf: report SKIP for arena tests a compiler cannot build

[Vineet Gupta <vineet.gupta@linux.dev>]

On 10/27/26 5:13 PM, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] selftests/bpf: missing __skip_without_arena fallback in jit_insns_arena.c
> --
>
> commit f37e4c1aa3e5f2decfc920dfa156617c4a66522b
> Author: Vineet Gupta <vineet.gupta@linux.dev>
>
> selftests/bpf: report SKIP for arena tests a compiler cannot build
>
> This commit adds a __skip_without_arena macro and #else fallback programs
> to BPF selftest files guarded by __BPF_FEATURE_ADDR_SPACE_CAST so that
> test_progs reports those subtests as skipped when built with a compiler
> that lacks arena address space support.
>
>> diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
>> index 1b264480e128f..ed1ed1b5bd097 100644
>> --- a/tools/testing/selftests/bpf/progs/bpf_misc.h
>> +++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
>> @@ -156,6 +160,16 @@
>>   #define __success		__test_tag("test_expect_success")
>>   #define __description(desc)	__test_tag("test_description=" desc)
>>   #define __skip(reason)		__test_tag("test_skip=" reason)
>> +
>> +/*
>> + * Without compiler arena support, report the test as SKIP rather than let it
>> + * pass vacuously or fail to load.
>> + */
>> +#ifdef __BPF_FEATURE_ADDR_SPACE_CAST
>> +#define __skip_without_arena
>> +#else
>> +#define __skip_without_arena	__skip("compiler does not support the arena address space")
>> +#endif
> [Severity: Medium]
> Should tools/testing/selftests/bpf/progs/jit_insns_arena.c also receive an
> #else fallback with a dummy arena_unsupported() program marked
> __skip_without_arena?
>
> In tools/testing/selftests/bpf/progs/jit_insns_arena.c, both BPF programs
> in the file (arena_zero_off() and cast_to_user()) are inside a
> __BPF_FEATURE_ADDR_SPACE_CAST guard without an #else branch:
>
> tools/testing/selftests/bpf/progs/jit_insns_arena.c:
>      #if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
>      SEC("syscall")
>      __success __retval(0)
>      int arena_zero_off(void *ctx)
>      {
>          ...
>      }
>
>      SEC("syscall")
>      __success __retval(0)
>      int cast_to_user(void *ctx)
>      {
>          ...
>      }
>      #endif
>
>      char _license[] SEC("license") = "GPL";
>
> When built with a compiler that does not define
> __BPF_FEATURE_ADDR_SPACE_CAST, such as stock bpf-gcc, jit_insns_arena.c
> compiles to an object with zero BPF programs. When test_jit_insns() in
> tools/testing/selftests/bpf/prog_tests/jit_insns.c runs:
>
>      test_jit_insns() -> RUN_TESTS(jit_insns_arena) -> test_loader__run_subtests()
>
> it silently executes zero subtests for jit_insns_arena instead of reporting
> a skipped subtest.

Indeed this was a miss because my prev testing baseline (before rebase) 
didn't have it.
Added in v2.

Thx,
-Vineet