From: Martin KaFai Lau <martin.lau@linux.dev>
To: Eduard Zingerman <eddyz87@gmail.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Yonghong Song <yonghong.song@linux.dev>,
Amery Hung <ameryhung@gmail.com>,
Kernel Team <kernel-team@meta.com>
Subject: Re: [PATCH v2 bpf-next 1/8] bpf: Add gen_epilogue to bpf_verifier_ops
Date: Wed, 21 Aug 2024 17:52:50 -0700 [thread overview]
Message-ID: <18149417-a51d-4760-ac99-04f4cf22fcbb@linux.dev> (raw)
In-Reply-To: <c67bb633ced9a345f35e12ee06e29fbc63318024.camel@gmail.com>
On 8/21/24 5:38 PM, Eduard Zingerman wrote:
> On Wed, 2024-08-21 at 17:34 -0700, Alexei Starovoitov wrote:
>
> [...]
>
>> Something like
>> insn_0
>> ...
>> r1 = 0
>> if rX == .. goto insn_0
>>
>> this jmp will be rewritten to point to newly added *(u64*)(r10 - ..) = r1
>>
>> so at run time it will overwrite that slot with zero and
>> epilogue will read zero from it instead of ctx.
>
> That's exactly what I tried on paper and jmp target was just moving down.
Thanks for bringing this up. I will try a test case to confirm.
next prev parent reply other threads:[~2024-08-22 0:53 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-21 23:34 [PATCH v2 bpf-next 0/8] bpf: Add gen_epilogue and allow kfunc call in pro/epilogue Martin KaFai Lau
2024-08-21 23:34 ` [PATCH v2 bpf-next 1/8] bpf: Add gen_epilogue to bpf_verifier_ops Martin KaFai Lau
2024-08-22 0:22 ` Alexei Starovoitov
2024-08-22 0:30 ` Eduard Zingerman
2024-08-22 0:34 ` Alexei Starovoitov
2024-08-22 0:38 ` Eduard Zingerman
2024-08-22 0:52 ` Martin KaFai Lau [this message]
2024-08-21 23:34 ` [PATCH v2 bpf-next 2/8] bpf: Export bpf_base_func_proto Martin KaFai Lau
2024-08-21 23:34 ` [PATCH v2 bpf-next 3/8] selftests/bpf: attach struct_ops maps before test prog runs Martin KaFai Lau
2024-08-21 23:34 ` [PATCH v2 bpf-next 4/8] selftests/bpf: Test gen_prologue and gen_epilogue Martin KaFai Lau
2024-08-21 23:34 ` [PATCH v2 bpf-next 5/8] selftests/bpf: Add tailcall epilogue test Martin KaFai Lau
2024-08-21 23:34 ` [PATCH v2 bpf-next 6/8] bpf: Add module parameter to gen_prologue and gen_epilogue Martin KaFai Lau
2024-08-21 23:34 ` [PATCH v2 bpf-next 7/8] bpf: Allow pro/epilogue to call kfunc Martin KaFai Lau
2024-08-22 1:32 ` Alexei Starovoitov
2024-08-22 6:09 ` Martin KaFai Lau
2024-08-22 13:47 ` Alexei Starovoitov
2024-08-22 17:38 ` Martin KaFai Lau
2024-08-22 17:58 ` Alexei Starovoitov
2024-08-21 23:34 ` [PATCH v2 bpf-next 8/8] selftests/bpf: Add kfunc call test in gen_prologue and gen_epilogue Martin KaFai Lau
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=18149417-a51d-4760-ac99-04f4cf22fcbb@linux.dev \
--to=martin.lau@linux.dev \
--cc=alexei.starovoitov@gmail.com \
--cc=ameryhung@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=kernel-team@meta.com \
--cc=yonghong.song@linux.dev \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox