From: Vineet Gupta <vineet.gupta@linux.dev>
To: bot+bpf-ci@kernel.org, ast@kernel.org, daniel@iogearbox.net,
andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com
Cc: martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev,
jolsa@kernel.org, emil@etsalapatis.com, ihor.solodrai@linux.dev,
john.fastabend@gmail.com, shuah@kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
martin.lau@kernel.org, mason@kernel.org
Subject: Re: [PATCH bpf-next v2 08/13] selftests/bpf: cover the low-32 link for sign-extending movs
Date: Fri, 11 Sep 2026 13:30:04 +0530 [thread overview]
Message-ID: <f0fa0178-4109-476d-b42b-0970b398de56@linux.dev> (raw)
In-Reply-To: <5c3e4124ce20a8c5b435ae68e4facd38b0dab5b9f643e74d014287dc9172076e@mail.kernel.org>
On 9/10/26 11:22 PM, bot+bpf-ci@kernel.org wrote:
>> selftests/bpf: cover the low-32 link for sign-extending movs
>>
>> Five programs, mirroring the zero-extending set:
>>
>> - sext_mov_wide_src: narrowing the source reaches the destination, and
>> the value that arrives is sign-extended rather than zero-extended
>> - sext_self_mov_keeps_link: r0 = (s32)r0 on an already-linked register
>> stays in its set, the shape a sign-extended int return takes
>> - sext_self_mov_no_link: the same mov on an unlinked register mints no id
>> - sext_no_sync_when_base_has_delta: a delta on the base stops propagation
>> - sext_no_sync_from_subreg_base: narrowing the link does not run
>> backwards into the rest of the set
>> - sext_kinds_reach_different_values: the same low half reaches -1 through
>> a sign extension and 0xffffffff through a zero extension
>>
>> Each guards a div by zero that is only unreachable if the propagation
>> happened, so losing the link is a verification failure rather than a test
>> that quietly stops checking anything.
> This isn't a bug, but should the count read "six programs", and could the
> closing sentence be scoped to the two __success programs, since
> sext_self_mov_no_link has no div and the __failure ones expect it to be
> reachable?
OK.
>> diff --git a/tools/testing/selftests/bpf/progs/bpf_misc.h b/tools/testing/selftests/bpf/progs/bpf_misc.h
>> index eb88d9ce6c34..45bfa02a5338 100644
>> --- a/tools/testing/selftests/bpf/progs/bpf_misc.h
>> +++ b/tools/testing/selftests/bpf/progs/bpf_misc.h
>> @@ -269,6 +269,14 @@
>> #define CAN_USE_BPF_ST
>> #endif
>>
>> +#if (defined(__TARGET_ARCH_arm64) || defined(__TARGET_ARCH_x86) || \
>> + (defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64) || \
>> + defined(__TARGET_ARCH_arm) || defined(__TARGET_ARCH_s390) || \
>> + defined(__TARGET_ARCH_loongarch)) && \
>> + (__clang_major__ >= 18 || defined(__BPF_FEATURE_MOVSX))
>> +#define CAN_USE_MOVSX
>> +#endif
>> +
> This isn't a bug, but now that the gate lives in bpf_misc.h, would it be
> worth switching verifier_movsx.c's inline #if over to #ifdef CAN_USE_MOVSX
> so the arch/feature list exists in one place?
Yes.
Thx,
-Vineet
>> diff --git a/tools/testing/selftests/bpf/progs/verifier_linked_scalars.c b/tools/testing/selftests/bpf/progs/verifier_linked_scalars.c
>> index 65cb0efd268f..9d060d8b0c1f 100644
> [ ... ]
>
>
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
>
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/34506184282
next prev parent reply other threads:[~2026-09-11 8:00 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-10 16:46 [PATCH bpf-next v2 00/13] bpf: track scalar equality across the low 32 bits Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 01/13] bpf: move linked-scalar flags out of bpf_reg_state->id [NFC] Vineet Gupta
2026-09-10 17:52 ` bot+bpf-ci
2026-09-10 16:46 ` [PATCH bpf-next v2 02/13] bpf: compare linked-scalar kinds in regs_exact() Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 03/13] bpf: track low-32 scalar equality across zero-extending movs Vineet Gupta
2026-09-10 17:52 ` bot+bpf-ci
2026-09-11 9:29 ` Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 04/13] selftests/bpf: cover the low-32 link for " Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 05/13] bpf: keep the range across a sign extension that cannot change it Vineet Gupta
2026-09-10 17:52 ` bot+bpf-ci
2026-09-11 10:37 ` Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 06/13] selftests/bpf: cover sign extensions that cannot change the range Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 07/13] bpf: track low-32 scalar equality across sign-extending movs Vineet Gupta
2026-09-10 17:52 ` bot+bpf-ci
2026-09-11 10:00 ` Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 08/13] selftests/bpf: cover the low-32 link for " Vineet Gupta
2026-09-10 17:52 ` bot+bpf-ci
2026-09-11 8:00 ` Vineet Gupta [this message]
2026-09-10 16:46 ` [PATCH bpf-next v2 09/13] bpf: track low-32 scalar equality across narrowing stack fills Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 10/13] selftests/bpf: cover the low-32 link for " Vineet Gupta
2026-09-10 17:31 ` bot+bpf-ci
2026-09-11 5:07 ` Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 11/13] bpf: record what a narrowing spill actually stores Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 12/13] bpf: track low-32 scalar equality across narrowing stack spills Vineet Gupta
2026-09-10 16:46 ` [PATCH bpf-next v2 13/13] selftests/bpf: cover the low-32 link for " Vineet Gupta
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