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authorHelge Deller <deller@gmx.de>2023-07-28 21:23:10 +0200
committerRichard Henderson <richard.henderson@linaro.org>2023-07-31 12:19:13 -0700
commit38dd78c41eaf08b490c9e7ec68fc508bbaa5cb1d (patch)
treec38b320054f6f57712cb52e806a12ed119acacc7 /linux-user
parent2e718e665706d5fcc3e3501bda26f277f055ed85 (diff)
linux-user/armeb: Fix __kernel_cmpxchg() for armeb
Commit 7f4f0d9ea870 ("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>
Diffstat (limited to 'linux-user')
-rw-r--r--linux-user/arm/cpu_loop.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/linux-user/arm/cpu_loop.c b/linux-user/arm/cpu_loop.c
index a992423257..b404117ff3 100644
--- a/linux-user/arm/cpu_loop.c
+++ b/linux-user/arm/cpu_loop.c
@@ -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;