From: "Philippe Mathieu-Daudé" <philmd@linaro.org>
To: Jiaxun Yang <jiaxun.yang@flygoat.com>, linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, tsbogend@alpha.franken.de,
johan.almbladh@anyfinetworks.com, paulburton@kernel.org,
bpf@vger.kernel.org
Subject: Re: [PATCH 2/2] MIPS: ebpf jit: Implement R4000 workarounds
Date: Sun, 26 Feb 2023 23:09:40 +0100 [thread overview]
Message-ID: <8529a744-721e-218d-7a4c-cbb523a1fc1d@linaro.org> (raw)
In-Reply-To: <20230222161222.11879-3-jiaxun.yang@flygoat.com>
On 22/2/23 17:12, Jiaxun Yang wrote:
> For R4000 erratas around multiplication and division instructions,
> as our use of those instructions are always followed by mflo/mfhi
> instructions, the only issue we need care is
>
> "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0" Errata 28:
> "A double-word or a variable shift may give an incorrect result if
> executed while an integer multiplication is in progress."
>
> We just emit a mfhi $0 to ensure the operation is completed after
> every multiplication instruction accorading to workaround suggestion
Typo "according"
> in the document.
>
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
> arch/mips/Kconfig | 4 +---
> arch/mips/net/bpf_jit_comp32.c | 4 ++++
> arch/mips/net/bpf_jit_comp64.c | 3 +++
> 3 files changed, 8 insertions(+), 3 deletions(-)
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
prev parent reply other threads:[~2023-02-26 22:09 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-22 16:12 [PATCH 0/2] MIPS: Implement two workarounds for BPF JIT Jiaxun Yang
2023-02-22 16:12 ` [PATCH 1/2] MIPS: ebpf jit: Implement DADDI workarounds Jiaxun Yang
2023-02-23 10:10 ` Johan Almbladh
2023-02-23 10:29 ` Jiaxun Yang
2023-02-27 12:17 ` Johan Almbladh
2023-02-27 15:17 ` Maciej W. Rozycki
2023-02-22 16:12 ` [PATCH 2/2] MIPS: ebpf jit: Implement R4000 workarounds Jiaxun Yang
2023-02-23 10:22 ` Johan Almbladh
2023-02-23 10:31 ` Jiaxun Yang
2023-02-27 12:19 ` Johan Almbladh
2023-02-27 15:18 ` Maciej W. Rozycki
2023-02-27 15:47 ` Jiaxun Yang
2023-02-26 22:09 ` Philippe Mathieu-Daudé [this message]
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