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,
eddyz87@gmail.com, kernel-team@fb.com, martin.lau@kernel.org,
mason@kernel.org, ihor.solodrai@linux.dev
Subject: Re: [PATCH bpf-next v9 14/23] bpf, arm64: Dispatch exception cleanup pads at run time
Date: Thu, 8 Oct 2026 18:23:12 +0200 [thread overview]
Message-ID: <9691f59d-a116-43f6-8fc8-09fc1891a395@linux.dev> (raw)
In-Reply-To: <e886b1d0457c718b5b198c480ed1c5040db1a43391b3c56028b659be85a82031@mail.kernel.org>
On 10/8/26 10:39 AM, bot+bpf-ci@kernel.org wrote:
>> bpf, arm64: Dispatch exception cleanup pads at run time
> TL;DR: Commit message only, no code issues: the changelog should open with a
> sentence saying what this does for arm64, and one bullet ("aux->epilogue_ip
> and the native cleanup table") lacks a verb.
>
>> bpf, arm64: Dispatch exception cleanup pads at run time
>>
>> - arch_bpf_stack_walk_ra(): walks the frame records with the kernel
>> unwinder, handing each return address to the consumer and storing a
>> new one back into the record it was read from. The first frame, whose
>> return into bpf_unwind() comes from the walk's own record, is
>> skipped.
>> - With CONFIG_ARM64_PTR_AUTH_KERNEL and a CPU that supports address
>> authentication, the new address is signed as the BPF prologue signs
>> the link register, with PACIASP and the record + 16 as modifier.
>> - aux->epilogue_ip and the native cleanup table.
>> - bpf_jit_supports_cleanup_pads() says yes, also with a shadow call
>> stack: only JITed frames' records are written, and JITed code keeps
>> no x18 copy of its return address.
>>
>> A pad needs no BTI: it is only reached as a return address.
>>
>> Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
> this isn't a bug, but could the changelog open with a sentence on what this
> does for arm64, instead of starting directly with a bullet list?
It is my fault. Should have a small paragraph to highlight the key
message before itemizing different cases.
>
> Also, the bullet "aux->epilogue_ip and the native cleanup table." has no
> verb. Could it say what is done with them, for example that the JIT records
> each function's epilogue address in aux->epilogue_ip and fills in the native
> cleanup ranges once the image is final?
I will expand to have more detailed information for this item.
>
>
> ---
> 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/37747693645
next prev parent reply other threads:[~2026-10-08 16:23 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-08 7:49 [PATCH bpf-next v9 00/23] bpf: Run exception cleanup landing pads when bpf_unwind() unwinds Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 01/23] bpf: Pack bpf_insn_aux_data flags into bit fields Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 02/23] bpf: Accept the compiler's exception cleanup table at program load Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 03/23] bpf: Add the bpf_unwind() and bpf_unwind_resume() kfuncs Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 04/23] bpf: Keep a call site's landing pad in insn_aux_data, add lookups Yonghong Song
2026-10-08 8:01 ` sashiko-bot
2026-10-08 15:58 ` Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 05/23] bpf: Mark covered call sites and check a program can take a table Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 06/23] bpf: Make exception landing pads reachable in the CFG Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 07/23] bpf: Verify an unwind through landing pads and epilogues Yonghong Song
2026-10-08 8:57 ` bot+bpf-ci
2026-10-08 16:07 ` Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 08/23] bpf: Refuse a landing pad that does not resume Yonghong Song
2026-10-08 8:57 ` bot+bpf-ci
2026-10-08 16:11 ` Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 09/23] bpf: Do not use a private stack for a program that can unwind Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 10/23] bpf: Prepare JITed programs for dispatching cleanup pads Yonghong Song
2026-10-08 7:50 ` [PATCH bpf-next v9 11/23] bpf: Dispatch cleanup pads by rewriting return addresses Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 12/23] bpf: Refuse a trampoline that calls a subprog that can unwind Yonghong Song
2026-10-08 8:14 ` sashiko-bot
2026-10-08 16:19 ` Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 13/23] bpf, x86: Dispatch exception cleanup pads at run time Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 14/23] bpf, arm64: " Yonghong Song
2026-10-08 8:39 ` bot+bpf-ci
2026-10-08 16:23 ` Yonghong Song [this message]
2026-10-08 7:51 ` [PATCH bpf-next v9 15/23] libbpf: Resolve the compiler's _Unwind_Resume to the kernel's kfunc Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 16/23] libbpf: Add cleanup_info to bpf_prog_load_opts Yonghong Song
2026-10-08 8:12 ` sashiko-bot
2026-10-08 16:25 ` Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 17/23] libbpf: Collect .bpf_cleanup records and pass them to the kernel Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 18/23] libbpf: Carry the exception cleanup table through the light skeleton Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 19/23] libbpf: Let the static linker carry .bpf_cleanup relocations Yonghong Song
2026-10-08 8:14 ` sashiko-bot
2026-10-08 16:26 ` Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 20/23] selftests/bpf: Add end-to-end and negative .bpf_cleanup exception tests Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 21/23] selftests/bpf: Add __set_global() and __ret_global() test tags Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 22/23] selftests/bpf: Cover more accepted .bpf_cleanup exception shapes Yonghong Song
2026-10-08 7:51 ` [PATCH bpf-next v9 23/23] selftests/bpf: Load an exception cleanup program from a light skeleton Yonghong Song
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