From: Yonghong Song <yonghong.song@linux.dev>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>, bpf@vger.kernel.org
Cc: Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Eduard Zingerman <eddyz87@gmail.com>,
kernel-team@fb.com
Subject: Re: [PATCH bpf-next 11/20] bpf, x86: Dispatch exception cleanup pads at run time
Date: Sat, 19 Sep 2026 12:13:44 -0700 [thread overview]
Message-ID: <978c00dd-073e-4850-928f-21a50b5b52ac@linux.dev> (raw)
In-Reply-To: <DLJ12W1FWIT3.3GC1GC68Q1ANU@gmail.com>
On 9/18/26 10:02 PM, Alexei Starovoitov wrote:
> On Wed, Sep 16, 2026 at 10:57 PM Yonghong Song <yonghong.song@linux.dev> wrote:
>> diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
>> index d4a980140b48..9d0dd54773e8 100644
>> --- a/arch/x86/net/bpf_jit_comp.c
>> +++ b/arch/x86/net/bpf_jit_comp.c
> [...]
>
>> + if (bpf_is_unwind_resume_kfunc(insn)) {
>> + emit_return(&prog, image + addrs[i - 1] + (prog - temp));
>> + break;
>> + }
>> +
>> func = (u8 *) __bpf_call_base + imm32;
> bpf_is_unwind_resume_kfunc() matches imm == btf_id && off == 0, but by
> now bpf_fixup_kfunc_call() has rewritten every other kfunc's imm to an
> offset from __bpf_call_base. A vmlinux kfunc that happens to sit
> btf_id bytes after __bpf_call_base gets JITed as a bare ret in the
> middle of a normal prog. Looks incorrect.
Right, bpf_is_unwind_resume_kfunc() is not correct as it compares
'imm == bpf_id' while imm has been rewritten.
Will fix.
next prev parent reply other threads:[~2026-09-19 19:13 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-17 5:56 [PATCH bpf-next 00/20] bpf: Run exception cleanup landing pads when bpf_throw() unwinds Yonghong Song
2026-09-17 5:56 ` [PATCH bpf-next 01/20] bpf: Accept the compiler's exception cleanup table at program load Yonghong Song
2026-09-17 5:56 ` [PATCH bpf-next 02/20] bpf: Add the bpf_unwind_resume() kfunc Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 03/20] bpf: Add lookups for exception cleanup resumes and landing pads Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 04/20] bpf: Mark the call sites an exception cleanup table covers Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 05/20] bpf: Make exception landing pads reachable in the CFG Yonghong Song
2026-09-17 6:22 ` sashiko-bot
2026-09-18 3:36 ` Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 06/20] bpf: Explore the landing pads no call site reaches Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 07/20] bpf: Refuse exception cleanup shapes bpf_throw() cannot dispatch Yonghong Song
2026-09-19 4:57 ` Alexei Starovoitov
2026-09-19 17:32 ` Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 08/20] bpf: Walk the exception unwind in the verifier Yonghong Song
2026-09-19 4:57 ` Alexei Starovoitov
2026-09-19 17:36 ` Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 09/20] bpf: Refuse a private stack for a program with an exception cleanup table Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 10/20] bpf: Dispatch exception cleanup pads from bpf_throw() Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 11/20] bpf, x86: Dispatch exception cleanup pads at run time Yonghong Song
2026-09-19 5:02 ` Alexei Starovoitov
2026-09-19 19:13 ` Yonghong Song [this message]
2026-09-17 5:57 ` [PATCH bpf-next 12/20] bpf, arm64: " Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 13/20] libbpf: Resolve the compiler's _Unwind_Resume to the kernel's kfunc Yonghong Song
2026-09-17 6:08 ` sashiko-bot
2026-09-17 7:00 ` bot+bpf-ci
2026-09-18 3:40 ` Yonghong Song
2026-09-17 5:57 ` [PATCH bpf-next 14/20] libbpf: Add cleanup_info to bpf_prog_load_opts Yonghong Song
2026-09-17 5:58 ` [PATCH bpf-next 15/20] libbpf: Collect .bpf_cleanup records and pass them to the kernel Yonghong Song
2026-09-17 6:12 ` sashiko-bot
2026-09-18 3:44 ` Yonghong Song
2026-09-17 5:58 ` [PATCH bpf-next 16/20] libbpf: Carry the exception cleanup table through the light skeleton Yonghong Song
2026-09-17 6:18 ` sashiko-bot
2026-09-18 3:52 ` Yonghong Song
2026-09-17 5:58 ` [PATCH bpf-next 17/20] libbpf: Let the static linker carry .bpf_cleanup relocations Yonghong Song
2026-09-17 6:16 ` sashiko-bot
2026-09-18 3:58 ` Yonghong Song
2026-09-17 5:58 ` [PATCH bpf-next 18/20] selftests/bpf: Add an end-to-end .bpf_cleanup exception test Yonghong Song
2026-09-17 6:12 ` sashiko-bot
2026-09-17 5:58 ` [PATCH bpf-next 19/20] selftests/bpf: Cover the exception cleanup shapes the chain does not reach Yonghong Song
2026-09-17 6:16 ` sashiko-bot
2026-09-17 5:58 ` [PATCH bpf-next 20/20] selftests/bpf: Load an exception cleanup program from a light skeleton Yonghong Song
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