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List:       qemu-devel
Subject:    [Qemu-devel] [PATCH] fix crash in set registers in PPC gdb-stub
From:       Jason Wessel <jason.wessel () windriver ! com>
Date:       2007-06-29 12:53:29
Message-ID: 468500C9.3040503 () windriver ! com
[Download RAW message or body]

While using the gdb stub on the PPC target you cannot set registers if 
the machine has the power save bit set in the msr without crashing 
QEMU.  The reason it crashes is because the cpu_loop_exit() function 
will get called when the gdb stub is setting the registers. 

There is certainly more than one way to fix problem.  I opted to add the 
check for the halted state to the store msr routine which is called from 
the the translated code or the gdb stub.  The halted state is always set 
when the stub is active.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

Jason.



["ppc_gdb_msr_fix.patch" (text/x-patch)]

---
 target-ppc/helper.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Index: qemu/target-ppc/helper.c
===================================================================
--- qemu.orig/target-ppc/helper.c
+++ qemu/target-ppc/helper.c
@@ -1493,10 +1493,12 @@ void do_store_msr (CPUPPCState *env, tar
         break;
     }
     if (enter_pm) {
-        /* power save: exit cpu loop */
-        env->halted = 1;
-        env->exception_index = EXCP_HLT;
-        cpu_loop_exit();
+        if (likely(!env->halted)) {
+            /* power save: exit cpu loop */
+            env->halted = 1;
+            env->exception_index = EXCP_HLT;
+            cpu_loop_exit();
+        }
     }
 }
 


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