From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/interrupt: Don't read MSR from interrupt_exit_kernel_prepare()
Date: Mon, 03 Jul 2023 15:26:58 +1000 [thread overview]
Message-ID: <168836201884.50010.18257455967677978392.b4-ty@ellerman.id.au> (raw)
In-Reply-To: <df36c6205ab64326fb1b991993c82057e92ace2f.1685955214.git.christophe.leroy@csgroup.eu>
On Mon, 05 Jun 2023 10:55:26 +0200, Christophe Leroy wrote:
> A disassembly of interrupt_exit_kernel_prepare() shows a useless read
> of MSR register. This is shown by r9 being re-used immediately without
> doing anything with the value read.
>
> c000e0e0: 60 00 00 00 nop
> c000e0e4: 7d 3a c2 a6 mfmd_ap r9
> c000e0e8: 7d 20 00 a6 mfmsr r9
> c000e0ec: 7c 51 13 a6 mtspr 81,r2
> c000e0f0: 81 3f 00 84 lwz r9,132(r31)
> c000e0f4: 71 29 80 00 andi. r9,r9,32768
>
> [...]
Applied to powerpc/next.
[1/1] powerpc/interrupt: Don't read MSR from interrupt_exit_kernel_prepare()
https://git.kernel.org/powerpc/c/0eb089a72fda3f7969e6277804bde75dc1474a14
cheers
WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>,
Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/interrupt: Don't read MSR from interrupt_exit_kernel_prepare()
Date: Mon, 03 Jul 2023 15:26:58 +1000 [thread overview]
Message-ID: <168836201884.50010.18257455967677978392.b4-ty@ellerman.id.au> (raw)
In-Reply-To: <df36c6205ab64326fb1b991993c82057e92ace2f.1685955214.git.christophe.leroy@csgroup.eu>
On Mon, 05 Jun 2023 10:55:26 +0200, Christophe Leroy wrote:
> A disassembly of interrupt_exit_kernel_prepare() shows a useless read
> of MSR register. This is shown by r9 being re-used immediately without
> doing anything with the value read.
>
> c000e0e0: 60 00 00 00 nop
> c000e0e4: 7d 3a c2 a6 mfmd_ap r9
> c000e0e8: 7d 20 00 a6 mfmsr r9
> c000e0ec: 7c 51 13 a6 mtspr 81,r2
> c000e0f0: 81 3f 00 84 lwz r9,132(r31)
> c000e0f4: 71 29 80 00 andi. r9,r9,32768
>
> [...]
Applied to powerpc/next.
[1/1] powerpc/interrupt: Don't read MSR from interrupt_exit_kernel_prepare()
https://git.kernel.org/powerpc/c/0eb089a72fda3f7969e6277804bde75dc1474a14
cheers
next prev parent reply other threads:[~2023-07-03 5:34 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-05 8:55 [PATCH] powerpc/interrupt: Don't read MSR from interrupt_exit_kernel_prepare() Christophe Leroy
2023-06-05 8:55 ` Christophe Leroy
2023-06-06 8:57 ` Nicholas Piggin
2023-06-06 8:57 ` Nicholas Piggin
2023-07-03 5:26 ` Michael Ellerman [this message]
2023-07-03 5:26 ` Michael Ellerman
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