Re: [PATCH bpf-next v3 3/8] selftests/bpf: report SKIP for arena tests a compiler cannot build

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

On 11/2/26 2:36 PM, Alexei Starovoitov wrote:
> On Mon, Nov 02, 2026 at 02:07 PM Vineet Gupta <vineet.gupta@linux.dev> wrote:
>> Give each guard an #else with a dummy marked __skip(), so the skip gap is
>> reported rather than invisible.  Add __skip_without_arena for it, which
>> expands to __skip() with a fixed reason when the compiler cannot do arena.
> How about the following approach instead...
> looks much simpler to me...

Agree: it does look simpler and they uncover more code to be tested now 
than being skipped.

Thx,
-Vineet

> pw-bot: cr
>
> diff --git a/tools/testing/selftests/bpf/progs/arena_kfunc_jit.c b/tools/testing/selftests/bpf/progs/arena_kfunc_jit.c
> index b5a01cb..16c3dd9 100644
> --- a/tools/testing/selftests/bpf/progs/arena_kfunc_jit.c
> +++ b/tools/testing/selftests/bpf/progs/arena_kfunc_jit.c
> @@ -23,8 +23,6 @@ struct {
>   /* volatile to force the scalar reloads below */
>   volatile u64 stash;
>
> -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
> -
>   SEC("syscall")
>   __arch_x86_64
>   __jited("...")
> @@ -93,6 +91,7 @@ __jited("	cbz	w4, L0")
>   __jited("	add	x4, x28, w4, uxtw")
>   __jited("L0:	{{.*}}")
>   __success
> +__skip_without_arena
>   int arena_arg_jit_args5(void *ctx)
>   {
>   	u64 __arena *val;
> @@ -113,6 +112,4 @@ int arena_arg_jit_args5(void *ctx)
>   	return 0;
>   }
>
> -#endif /* __BPF_FEATURE_ADDR_SPACE_CAST */
> -
>   char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
> index d7f706c..4ec840b 100644
> --- a/tools/testing/selftests/bpf/progs/bpf_misc.h
> +++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
> @@ -116,6 +116,10 @@
>    *                   feature the toolchain or JIT cannot provide, so a run does
>    *                   not report OK for coverage it never executed.
>    *
> + * __skip_without_arena
> + *                   __skip() when the compiler does not support the arena
> + *                   address space, nothing otherwise.
> + *
>    * __log_level       Log level to use for the program, numeric value expected.
>    *
>    * __flag            Adds one flag use for the program, the following values are valid:
> @@ -156,6 +160,11 @@
>   #define __success		__test_tag("test_expect_success")
>   #define __description(desc)	__test_tag("test_description=" desc)
>   #define __skip(reason)		__test_tag("test_skip=" reason)
> +#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
>   #define __msg_unpriv(msg)	__test_tag("test_expect_msg_unpriv=" msg)
>   #define __not_msg_unpriv(msg)	__test_tag("test_expect_not_msg_unpriv=" msg)
>   #define __msg_next_unpriv(msg)	__test_tag("test_expect_msg_next_unpriv=" msg)
> diff --git a/tools/testing/selftests/bpf/progs/jit_insns_arena.c b/tools/testing/selftests/bpf/progs/jit_insns_arena.c
> index 95736ea..77d135a 100644
> --- a/tools/testing/selftests/bpf/progs/jit_insns_arena.c
> +++ b/tools/testing/selftests/bpf/progs/jit_insns_arena.c
> @@ -106,6 +106,14 @@ int cast_to_user(void *ctx)
>   	: "r1", "r2", "r7", "r9");
>   	return res != 0;
>   }
> +#else
> +SEC("socket")
> +__skip_without_arena
> +__success
> +int arena_unsupported(void)
> +{
> +	return 0;
> +}
>   #endif
>
>   char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_large.c b/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> index dbdea14..428b984 100644
> --- a/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> +++ b/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> @@ -181,7 +181,6 @@ int free_reserved(void *ctx)
>   	return 0;
>   }
>
> -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
>   #define PAGE_CNT 100
>   __u8 __arena * __arena page[PAGE_CNT]; /* occupies the first page */
>   __u8 __arena *base;
> @@ -220,6 +219,7 @@ __noinline int alloc_pages(int page_cnt, int pages_atonce, bool first_pass,
>
>   SEC("syscall")
>   __success __retval(0)
> +__skip_without_arena
>   int big_alloc2(void *ctx)
>   {
>   	__u8 __arena *pg;
> @@ -290,9 +290,9 @@ int big_alloc2(void *ctx)
>   /* Nonsleepable because it binds to a socket program. */
>   SEC("socket")
>   __success __retval(0)
> +__skip_without_arena
>   int big_alloc3(void *ctx)
>   {
> -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
>   	char __arena *pages;
>   	u64 i;
>   	int err = 0;
> @@ -314,16 +314,14 @@ int big_alloc3(void *ctx)
>
>   	bpf_arena_free_pages(&arena, pages, LARGE_PAGE_CNT);
>   	return err;
> -#endif
> -	return 0;
>   }
>
>   /* SYSCALL programs are always sleepable. */
>   SEC("syscall")
>   __success __retval(0)
> +__skip_without_arena
>   int big_alloc4(void *ctx)
>   {
> -#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
>   	char __arena *pages;
>   	u64 i;
>   	int err = 0;
> @@ -345,8 +343,6 @@ int big_alloc4(void *ctx)
>
>   	bpf_arena_free_pages(&arena, pages, LARGE_PAGE_CNT);
>   	return err;
> -#endif
> -	return 0;
>   }
> -#endif
> +
>   char _license[] SEC("license") = "GPL";