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linux-user/armeb: Fix __kernel_cmpxchg() for armeb

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Commit 7f4f0d9ea8 ("linux-user/arm: Implement __kernel_cmpxchg with host
atomics") switched to use qatomic_cmpxchg() to swap a word with the memory
content, but missed to endianess-swap the oldval and newval values when
emulating an armeb CPU, which expects words to be stored in big endian in
the guest memory.

The bug can be verified with qemu >= v7.0 on any little-endian host, when
starting the armeb binary of the upx program, which just hangs without
this patch.

Cc: qemu-stable@nongnu.org
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Reported-by: John Reiser <jreiser@BitWagon.com>
Closes: https://github.com/upx/upx/issues/687
Message-Id: <ZMQVnqY+F+5sTNFd@p100>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Helge Deller 2023-07-28 21:23:10 +02:00 committed by Richard Henderson
parent 2e718e6657
commit 38dd78c41e
1 changed files with 7 additions and 2 deletions
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9
linux-user/arm/cpu_loop.c
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@ -117,8 +117,9 @@ static void arm_kernel_cmpxchg32_helper(CPUARMState *env)
{
uint32_t oldval, newval, val, addr, cpsr, *host_addr;
oldval = env->regs[0];
newval = env->regs[1];
/* Swap if host != guest endianness, for the host cmpxchg below */
oldval = tswap32(env->regs[0]);
newval = tswap32(env->regs[1]);
addr = env->regs[2];
mmap_lock();
@ -174,6 +175,10 @@ static void arm_kernel_cmpxchg64_helper(CPUARMState *env)
return;
}
/* Swap if host != guest endianness, for the host cmpxchg below */
oldval = tswap64(oldval);
newval = tswap64(newval);
#ifdef CONFIG_ATOMIC64
val = qatomic_cmpxchg__nocheck(host_addr, oldval, newval);
cpsr = (val == oldval) * CPSR_C;