From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Liyuan Pang <pangliyuan1@huawei.com>
Cc: nathan@kernel.org, nick.desaulniers+lkml@gmail.com,
morbo@google.com, justinstitt@google.com, nico@fluxnic.net,
will@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
xieyuanbin1@huawei.com, wanqian10@huawei.com
Subject: Re: [PATCH] ARM: fix input-only operand modification in load_unaligned_zeropad()
Date: Mon, 8 Dec 2025 09:47:16 +0000 [thread overview]
Message-ID: <aTaepMnRKqCM1IJe@shell.armlinux.org.uk> (raw)
In-Reply-To: <20251127025848.363992-1-pangliyuan1@huawei.com>
On Thu, Nov 27, 2025 at 10:58:48AM +0800, Liyuan Pang wrote:
> In the inline assembly inside load_unaligned_zeropad(), the "addr" is
> constrained as input-only operand. The compiler assumes that on exit
> from the asm statement these operands contain the same values as they
> had before executing the statement, but when kernel page fault happened,
> the assembly fixup code "bic %2 %2, #0x3" modify the value of "addr",
> which may lead to an unexpected behavior.
>
> Use a temporary variable "tmp" to handle it, instead of modifying the
> input-only operand, just like what arm64's load_unaligned_zeropad()
> does.
>
> Fixes: b9a50f74905a ("ARM: 7450/1: dcache: select DCACHE_WORD_ACCESS for little-endian ARMv6+ CPUs")
>
> Co-developed-by: Xie Yuanbin <xieyuanbin1@huawei.com>
> Signed-off-by: Xie Yuanbin <xieyuanbin1@huawei.com>
> Signed-off-by: Liyuan Pang <pangliyuan1@huawei.com>
Sorry, I missed this email in the deluge. This looks entirely correct.
Please submit this to the patch system. Details in the signature below.
Thanks.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
prev parent reply other threads:[~2025-12-08 9:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-27 2:58 [PATCH] ARM: fix input-only operand modification in load_unaligned_zeropad() Liyuan Pang
2025-12-08 9:47 ` Russell King (Oracle) [this message]
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