From 38dd78c41eaf08b490c9e7ec68fc508bbaa5cb1d Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Fri, 28 Jul 2023 21:23:10 +0200 Subject: [PATCH] linux-user/armeb: Fix __kernel_cmpxchg() for armeb MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Reported-by: "Markus F.X.J. Oberhumer" Reported-by: John Reiser Closes: https://github.com/upx/upx/issues/687 Message-Id: Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Richard Henderson Signed-off-by: Richard Henderson --- linux-user/arm/cpu_loop.c | 9 +++++++-- 1 file 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; -- 2.30.2