From: Yonghong Song <yonghong.song@linux.dev>
To: Eduard Zingerman <eddyz87@gmail.com>,
bpf@vger.kernel.org, ast@kernel.org
Cc: andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev,
kernel-team@fb.com, jose.marchesi@oracle.com
Subject: Re: [PATCH bpf-next v2 3/5] bpf: support bpf_fastcall patterns for kfuncs
Date: Wed, 21 Aug 2024 18:23:02 -0700 [thread overview]
Message-ID: <db0c935c-6997-425b-9e0d-d5bf13beffcc@linux.dev> (raw)
In-Reply-To: <20240817015140.1039351-4-eddyz87@gmail.com>
On 8/16/24 6:51 PM, Eduard Zingerman wrote:
> Recognize bpf_fastcall patterns around kfunc calls.
> For example, suppose bpf_cast_to_kern_ctx() follows bpf_fastcall
> contract (which it does), in such a case allow verifier to rewrite BPF
> program below:
>
> r2 = 1;
> *(u64 *)(r10 - 32) = r2;
> call %[bpf_cast_to_kern_ctx];
> r2 = *(u64 *)(r10 - 32);
> r0 = r2;
>
> By removing the spill/fill pair:
>
> r2 = 1;
> call %[bpf_cast_to_kern_ctx];
> r0 = r2;
>
> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
next prev parent reply other threads:[~2024-08-22 1:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-17 1:51 [PATCH bpf-next v2 0/5] support bpf_fastcall patterns for calls to kfuncs Eduard Zingerman
2024-08-17 1:51 ` [PATCH bpf-next v2 1/5] bpf: rename nocsr -> bpf_fastcall in verifier Eduard Zingerman
2024-08-22 1:14 ` Yonghong Song
2024-08-22 1:17 ` Yonghong Song
2024-08-22 1:43 ` Eduard Zingerman
2024-08-17 1:51 ` [PATCH bpf-next v2 2/5] selftests/bpf: rename nocsr -> bpf_fastcall in selftests Eduard Zingerman
2024-08-22 1:20 ` Yonghong Song
2024-08-17 1:51 ` [PATCH bpf-next v2 3/5] bpf: support bpf_fastcall patterns for kfuncs Eduard Zingerman
2024-08-17 20:09 ` kernel test robot
2024-08-18 2:50 ` Eduard Zingerman
2024-08-22 1:23 ` Yonghong Song [this message]
2024-08-17 1:51 ` [PATCH bpf-next v2 4/5] bpf: allow bpf_fastcall for bpf_cast_to_kern_ctx and bpf_rdonly_cast Eduard Zingerman
2024-08-22 1:23 ` Yonghong Song
2024-08-17 1:51 ` [PATCH bpf-next v2 5/5] selftests/bpf: check if bpf_fastcall is recognized for kfuncs Eduard Zingerman
2024-08-22 1:38 ` Yonghong Song
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