From: Eduard Zingerman <eddyz87@gmail.com>
To: Yonghong Song <yonghong.song@linux.dev>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
kernel-team@fb.com, Martin KaFai Lau <martin.lau@kernel.org>
Subject: Re: [PATCH bpf-next v3 1/2] bpf: Get better reg range with ldsx and 32bit compare
Date: Mon, 15 Jul 2024 16:55:42 -0700 [thread overview]
Message-ID: <3594134da3dd50a5e7fca62d9843c47a8b47ce9a.camel@gmail.com> (raw)
In-Reply-To: <20240712234359.287698-1-yonghong.song@linux.dev>
On Fri, 2024-07-12 at 16:43 -0700, Yonghong Song wrote:
[...]
> This patch fixed the issue by adding additional register deduction after 32-bit compare
> insn. If the signed 32-bit register range is non-negative then 64-bit smin is
> in range of [S32_MIN, S32_MAX], then the actual 64-bit smin/smax should be the same
> as 32-bit smin32/smax32.
[...]
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
[...]
> + * Now, suppose that register range is in fact tighter:
> + * [0xffff_ffff_8000_0000, 0x0000_0000_ffff_ffff] (R)
> + * Also suppose that it's 32-bit range is positive,
> + * meaning that lower 32-bits of the full 64-bit register
> + * are in the range:
> + * [0x0000_0000, 0x7fff_ffff] (W)
> + *
> + * It this happens, then any value in a range:
^^
Sorry, one more typo, should be "If".
Maybe could be changed when the patch would be applied.
[...]
next prev parent reply other threads:[~2024-07-15 23:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-12 23:43 [PATCH bpf-next v3 1/2] bpf: Get better reg range with ldsx and 32bit compare Yonghong Song
2024-07-12 23:44 ` [PATCH bpf-next v3 2/2] selftests/bpf: Add ldsx selftests for ldsx and subreg compare Yonghong Song
2024-07-16 0:44 ` Eduard Zingerman
2024-07-16 22:38 ` Yonghong Song
2024-07-17 0:12 ` Eduard Zingerman
2024-07-17 6:06 ` Yonghong Song
2024-07-15 23:55 ` Eduard Zingerman [this message]
2024-07-17 7:27 ` [PATCH bpf-next v3 1/2] bpf: Get better reg range with ldsx and 32bit compare Shung-Hsi Yu
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