On 02/23/2010 03:50 PM, Jay Foad wrote:
I'm building QEMU mipsel-linux-user with Ubuntu's GCC 4.4 on an x86
host. Whenever I try to run a trivial MIPS executable, QEMU segfaults
in cpu_loop() shortly after the call to cpu_mips_exec().
The problem seems to be that cpu_exec() doesn't preserve ebp. It tries to:
saved_env_reg = (host_reg_t) env;
where env is a global variable decorated with asm("ebp"). This saves
ebp to the stack, but later on, in some function inlined into
cpu_exec(), the value on the stack gets overwritten with something
else.
Can you try this patch:
diff --git a/cpu-exec.c b/cpu-exec.c
index 51aa416..bfaf908 100644
--- a/cpu-exec.c
+++ b/cpu-exec.c
@@ -215,7 +215,7 @@ static void cpu_handle_debug_exception(CPUState *env)
int cpu_exec(CPUState *env1)
{
- host_reg_t saved_env_reg;
+ volatile host_reg_t saved_env_reg;
int ret, interrupt_request;
TranslationBlock *tb;
uint8_t *tc_ptr;
@@ -230,8 +230,8 @@ int cpu_exec(CPUState *env1)
value, so that files not including target-xyz/exec.h are free to
use it. */
QEMU_BUILD_BUG_ON (sizeof (saved_env_reg) != sizeof (env));
- saved_env_reg = (host_reg_t) env;
asm("");
+ saved_env_reg = (host_reg_t) env;
env = env1;
#if defined(TARGET_I386)
and if it works, possibly only each hunk of it?
Paolo
