On Thu, Oct 15, 2015 at 10:17:47AM +0100, Vladimir Murzin wrote:
> We might need the same change for arm64 counterpart (see
> arch/arm64/kernel/armv8_deprecated.c).
Something like below?
Will
>From 63c3e83073cfac2e011adf0ed6f335275cc977a7 Mon Sep 17 00:00:00 2001
From: Will Deacon <will.dea...@arm.com>
Date: Thu, 15 Oct 2015 13:55:53 +0100
Subject: [PATCH] arm64: compat: fix stxr failure case in SWP emulation
If the STXR instruction fails in the SWP emulation code, we leave *data
overwritten with the loaded value, therefore corrupting the data written
by a subsequent, successful attempt.
This patch re-jigs the code so that we only write back to *data once we
know that the update has happened.
Reported-by: Shengjiu Wang <shengjiu.w...@freescale.com>
Reported-by: Vladimir Murzin <vladimir.mur...@arm.com>
Signed-off-by: Will Deacon <will.dea...@arm.com>
---
arch/arm64/kernel/armv8_deprecated.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/armv8_deprecated.c
b/arch/arm64/kernel/armv8_deprecated.c
index bcee7abac68e..6039d1eb5912 100644
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -284,12 +284,12 @@ static void register_insn_emulation_sysctl(struct
ctl_table *table)
__asm__ __volatile__( \
ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \
CONFIG_ARM64_PAN) \
- " mov %w2, %w1\n" \
- "0: ldxr"B" %w1, [%3]\n" \
- "1: stxr"B" %w0, %w2, [%3]\n" \
+ "0: ldxr"B" %w2, [%3]\n" \
+ "1: stxr"B" %w0, %w1, [%3]\n" \
" cbz %w0, 2f\n" \
" mov %w0, %w4\n" \
"2:\n" \
+ " mov %w1, %w2\n" \
" .pushsection .fixup,\"ax\"\n" \
" .align 2\n" \
"3: mov %w0, %w5\n" \
--
2.1.4
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