From: Yonghong Song <yonghong.song@linux.dev>
To: bot+bpf-ci@kernel.org, bpf@vger.kernel.org
Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net,
jose.marchesi@oracle.com, kernel-team@fb.com,
martin.lau@kernel.org, eddyz87@gmail.com, clm@meta.com,
ihor.solodrai@linux.dev
Subject: Re: [PATCH bpf-next v4 12/18] bpf: Reject stack arguments if tail call reachable
Date: Mon, 13 Apr 2026 09:37:42 -0700 [thread overview]
Message-ID: <ba80e1ba-a290-47d6-8f61-9bcb63a996ba@linux.dev> (raw)
In-Reply-To: <f163dcbf46e9511eba14b22ed10467984bda3bf07a3d1bd6cd27ae14eadc2056@mail.kernel.org>
On 4/11/26 10:43 PM, bot+bpf-ci@kernel.org wrote:
>> Tailcalls are been deprecated. So reject stack arguments
>> if tail call is in the way.
> The commit message has a grammar issue ("are been" should probably
> be "have been" or "are being"), but more importantly, is the claim
> that tail calls are deprecated accurate?
>
> Looking at the mailing list discussion on the v1 series, Alexei's
> guidance was "let's disallow mixing 6+ args and tailcalls" due to
> stack frame layout incompatibility, not because tail calls are being
> deprecated.
>
> Could the commit message more precisely describe the actual
> reason for the restriction? Something along the lines of "tail
> calls and stack arguments require incompatible stack frame
> handling" would better explain to future readers why the
> combination is rejected.
Okay. Will update the commit message.
>
>
> ---
> 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/24299298635
next prev parent reply other threads:[~2026-04-13 16:38 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-12 4:58 [PATCH bpf-next v4 00/18] bpf: Support stack arguments for BPF functions and kfuncs Yonghong Song
2026-04-12 4:58 ` [PATCH bpf-next v4 01/18] bpf: Remove unused parameter from check_map_kptr_access() Yonghong Song
2026-04-12 4:58 ` [PATCH bpf-next v4 02/18] bpf: Change from "arg #%d" to "arg#%d" in verifier log Yonghong Song
2026-04-12 4:58 ` [PATCH bpf-next v4 03/18] bpf: Refactor to avoid redundant calculation of bpf_reg_state Yonghong Song
2026-04-12 5:31 ` bot+bpf-ci
2026-04-13 14:25 ` Yonghong Song
2026-04-12 4:58 ` [PATCH bpf-next v4 04/18] bpf: Refactor to handle memory and size together Yonghong Song
2026-04-12 5:31 ` bot+bpf-ci
2026-04-13 14:27 ` Yonghong Song
2026-04-12 4:58 ` [PATCH bpf-next v4 05/18] bpf: Change some regno type from u32 to int type Yonghong Song
2026-04-12 4:58 ` [PATCH bpf-next v4 06/18] bpf: Use argument index instead of register index in kfunc verifier logs Yonghong Song
2026-04-12 5:43 ` bot+bpf-ci
2026-04-13 14:37 ` Yonghong Song
2026-04-12 22:01 ` Alexei Starovoitov
2026-04-13 14:45 ` Yonghong Song
2026-04-15 23:23 ` Amery Hung
2026-04-12 4:59 ` [PATCH bpf-next v4 07/18] bpf: Introduce bpf register BPF_REG_STACK_ARG_BASE Yonghong Song
2026-04-12 4:59 ` [PATCH bpf-next v4 08/18] bpf: Reuse MAX_BPF_FUNC_ARGS for maximum number of arguments Yonghong Song
2026-04-12 4:59 ` [PATCH bpf-next v4 09/18] bpf: Support stack arguments for bpf functions Yonghong Song
2026-04-12 5:43 ` bot+bpf-ci
2026-04-13 15:22 ` Yonghong Song
2026-04-12 22:23 ` Alexei Starovoitov
2026-04-13 16:33 ` Yonghong Song
2026-04-12 5:00 ` [PATCH bpf-next v4 10/18] bpf: Fix interaction between stack argument PTR_TO_STACK and dead slot poisoning Yonghong Song
2026-04-12 5:43 ` bot+bpf-ci
2026-04-13 16:36 ` Yonghong Song
2026-04-15 22:32 ` Amery Hung
2026-04-12 5:00 ` [PATCH bpf-next v4 11/18] bpf: Reject stack arguments in non-JITed programs Yonghong Song
2026-04-12 5:00 ` [PATCH bpf-next v4 12/18] bpf: Reject stack arguments if tail call reachable Yonghong Song
2026-04-12 5:43 ` bot+bpf-ci
2026-04-13 16:37 ` Yonghong Song [this message]
2026-04-12 5:00 ` [PATCH bpf-next v4 13/18] bpf: Support stack arguments for kfunc calls Yonghong Song
2026-04-12 5:43 ` bot+bpf-ci
2026-04-13 16:43 ` Yonghong Song
2026-04-12 5:00 ` [PATCH bpf-next v4 14/18] bpf: Enable stack argument support for x86_64 Yonghong Song
2026-04-12 5:00 ` [PATCH bpf-next v4 15/18] bpf,x86: Implement JIT support for stack arguments Yonghong Song
2026-04-12 5:43 ` bot+bpf-ci
2026-04-13 16:49 ` Yonghong Song
2026-04-12 22:36 ` Alexei Starovoitov
2026-04-13 17:26 ` Yonghong Song
2026-04-13 19:59 ` Alexei Starovoitov
2026-04-13 20:32 ` Yonghong Song
2026-04-13 20:38 ` Alexei Starovoitov
2026-04-13 21:10 ` Yonghong Song
2026-04-14 16:45 ` Yonghong Song
2026-04-14 17:51 ` Alexei Starovoitov
2026-04-12 5:00 ` [PATCH bpf-next v4 16/18] selftests/bpf: Add tests for BPF function " Yonghong Song
2026-04-12 5:00 ` [PATCH bpf-next v4 17/18] selftests/bpf: Add negative test for greater-than-8-byte kfunc stack argument Yonghong Song
2026-04-12 5:00 ` [PATCH bpf-next v4 18/18] selftests/bpf: Add verifier tests for stack argument validation Yonghong Song
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