From: Eduard Zingerman <eddyz87@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
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 17:38:14 -0700 [thread overview]
Message-ID: <c67bb633ced9a345f35e12ee06e29fbc63318024.camel@gmail.com> (raw)
In-Reply-To: <CAADnVQ++V49=-_bK_dSvxG-WxYEOT=3m1u8tQH1ArALKDy+WhA@mail.gmail.com>
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.
next prev parent reply other threads:[~2024-08-22 0:38 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 [this message]
2024-08-22 0:52 ` Martin KaFai Lau
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
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