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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=9691f59d-a116-43f6-8fc8-09fc1891a395@linux.dev \
--to=yonghong.song@linux.dev \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bot+bpf-ci@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=ihor.solodrai@linux.dev \
--cc=kernel-team@fb.com \
--cc=martin.lau@kernel.org \
--cc=mason@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.