On Thu, 2026-08-13 at 12:01 +0000, Yiyang Chen wrote:
> Add a verifier test with one atomic RMW instruction reached through
> PTR_TO_ARENA and PTR_TO_MAP_VALUE paths. The verifier must reject the
> shared instruction with the existing incompatible-pointer diagnostic.
>
> Signed-off-by: Yiyang Chen <[email protected]>
> ---
> tools/testing/selftests/bpf/progs/verifier_arena.c | 44
> ++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/progs/verifier_arena.c
> b/tools/testing/selftests/bpf/progs/verifier_arena.c
> index b241bbcf54a8a..2e43da188194b 100644
> --- a/tools/testing/selftests/bpf/progs/verifier_arena.c
> +++ b/tools/testing/selftests/bpf/progs/verifier_arena.c
> @@ -25,6 +25,15 @@ struct {
> __ulong(map_extra, ARENA_VM_START); /* start of mmap() region */
> } arena SEC(".maps");
>
> +struct {
> + __uint(type, BPF_MAP_TYPE_ARRAY);
> + __uint(max_entries, 1);
> + __type(key, __u32);
> + __type(value, __u64);
> +} atomic_map SEC(".maps");
Please use existing arena map.
> +
> +static __u64 arena_atomic_target SEC(".addr_space.1");
The bot is right, verifier_arena tests are failing.
Did you test this patch before sending?
> SEC("socket")
> __success __retval(0)
> int basic_alloc1_nosleep(void *ctx)
> @@ -637,6 +646,41 @@ int non_arena_ptr_add_to_arena_ptr(void *ctx)
>
> #endif
>
> +SEC("socket")
> +__description("arena and map value atomic at the same instruction")
> +__failure __msg("same insn cannot be used with different pointers")
> +__arch_x86_64
> +__load_if_JITed()
> +__naked void mixed_arena_map_value_atomic(void)
> +{
> + asm volatile (" \
> + r1 = 0; \
> + *(u32 *)(r10 - 4) = r1; \
> + r2 = r10; \
> + r2 += -4; \
> + r1 = %[atomic_map] ll; \
> + call %[bpf_map_lookup_elem]; \
> + if r0 == 0 goto 1f; \
> + r6 = r0; \
> + r7 = %[arena_atomic_target] ll; \
> + .byte 0xbf; .byte 0x77; .short 1; .long 1; \
Please use __imm_insn, see examples in the test suite.
> + call %[bpf_get_prandom_u32]; \
> + if w0 != 0 goto 2f; \
> + r8 = r6; \
> + goto 3f; \
> +2: r8 = r7; \
> +3: r9 = 1; \
> + lock *(u64 *)(r8 + 0) += r9; \
> +1: r0 = 0; \
> + exit; \
> +" :
> + : __imm_addr(atomic_map),
> + __imm_addr(arena_atomic_target),
You can conjure an arena pointer as in non_arena_ptr_add_to_arena_ptr()
w/o the need for the variable.
> + __imm(bpf_map_lookup_elem),
> + __imm(bpf_get_prandom_u32)
> + : __clobber_all);
> +}
> +
> static __noinline
> u32 __arena *check_arena_arg_nonglobal(u32 __arena *arg)
> {
pw-bot: cr.
