From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, arnd@arndb.de,
linus.walleij@linaro.org, stable@vger.kernel.org
Subject: Re: [PATCH] ARM: Thumb2: align ALT_UP() sections sufficiently
Date: Tue, 18 Jan 2022 11:21:20 +0000 [thread overview]
Message-ID: <YeaisFN1ru7suF1Y@shell.armlinux.org.uk> (raw)
In-Reply-To: <20220118102756.1259149-1-ardb@kernel.org>
On Tue, Jan 18, 2022 at 11:27:56AM +0100, Ard Biesheuvel wrote:
> When building for Thumb2, the .alt.smp.init sections that are emitted by
> the ALT_UP() patching code may not be 32-bit aligned, even though the
> fixup_smp_on_up() routine expects that. This results in alignment faults
> at module load time, which need to be fixed up by the fault handler.
>
> So let's align those sections explicitly, and avoid this from occurring.
Are you seeing a problem that this patch fixes?
This really should not matter. .alt.smp.init contents are always a whole
number of 32-bit words. These are gathered by the linker into the
.init.smpalt section, so the contents should always be a whole number
of 32-bit words.
This follows the .init.tagtable section, which is also a 32-bit word
aligned structure built by the linker... which follows the
.init.arch.info section and .init.proc.info sections which all have
32-bit alignment requirements.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
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WARNING: multiple messages have this Message-ID (diff)
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, arnd@arndb.de,
linus.walleij@linaro.org, stable@vger.kernel.org
Subject: Re: [PATCH] ARM: Thumb2: align ALT_UP() sections sufficiently
Date: Tue, 18 Jan 2022 11:21:20 +0000 [thread overview]
Message-ID: <YeaisFN1ru7suF1Y@shell.armlinux.org.uk> (raw)
In-Reply-To: <20220118102756.1259149-1-ardb@kernel.org>
On Tue, Jan 18, 2022 at 11:27:56AM +0100, Ard Biesheuvel wrote:
> When building for Thumb2, the .alt.smp.init sections that are emitted by
> the ALT_UP() patching code may not be 32-bit aligned, even though the
> fixup_smp_on_up() routine expects that. This results in alignment faults
> at module load time, which need to be fixed up by the fault handler.
>
> So let's align those sections explicitly, and avoid this from occurring.
Are you seeing a problem that this patch fixes?
This really should not matter. .alt.smp.init contents are always a whole
number of 32-bit words. These are gathered by the linker into the
.init.smpalt section, so the contents should always be a whole number
of 32-bit words.
This follows the .init.tagtable section, which is also a 32-bit word
aligned structure built by the linker... which follows the
.init.arch.info section and .init.proc.info sections which all have
32-bit alignment requirements.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2022-01-18 11:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-18 10:27 [PATCH] ARM: Thumb2: align ALT_UP() sections sufficiently Ard Biesheuvel
2022-01-18 10:27 ` Ard Biesheuvel
2022-01-18 11:21 ` Russell King (Oracle) [this message]
2022-01-18 11:21 ` Russell King (Oracle)
2022-01-18 11:32 ` Ard Biesheuvel
2022-01-18 11:32 ` Ard Biesheuvel
2022-01-18 11:35 ` Russell King (Oracle)
2022-01-18 11:35 ` Russell King (Oracle)
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