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From: jan.kiszka@siemens.com (Jan Kiszka)
Subject: [Qemu-devel] [PATCH 2/5] kqemu: i386: Reorder DS and ES on
exception stack
Date: Fri, 29 May 2009 19:18:31 +0200
Message-ID: <20090529171831.14265.74474.stgit@mchn012c.ww002.siemens.net>
To: qemu-devel@nongnu.org
This is a KQEMU upstream bug: In case the non-trivial paths of
LOAD_SEG_CACHE in exception_return are taken for both DS and ES, the
current code will break as it assumes to read from the monitor's DS in
the restore code for ES. Fix this by swapping both segments on the stack
so that ES is always restored before DS.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
common/i386/monitor_asm.S | 16 ++++++++--------
common/kqemu_int.h | 6 +++---
2 files changed, 11 insertions(+), 11 deletions(-)
diff --git common/i386/monitor_asm.S b/common/i386/monitor_asm.S
index 04f4258..e996553 100644
Index: common/i386/monitor_asm.S
--- common/i386/monitor_asm.S
+++ common/i386/monitor_asm.S
@@ -214,8 +214,8 @@ __monitor_exception:
pushl %edx
pushl %ecx
pushl %eax
- pushl %es
pushl %ds
+ pushl %es
/* compute the address of the monitor context */
call 1f
@@ -260,17 +260,17 @@ exception_return:
cmpb $3, KQEMU_STATE_cpu_state_cpl(%ebx)
je normal_seg_load
popl %eax
- LOAD_SEG_CACHE(%ds, R_DS, (11 * 4))
+ LOAD_SEG_CACHE(%es, R_ES, (11 * 4))
popl %eax
- LOAD_SEG_CACHE(%es, R_ES, (10 * 4))
+ LOAD_SEG_CACHE(%ds, R_DS, (10 * 4))
jmp 2f
normal_seg_load:
#endif
1:
- popl %ds
+ popl %es
SEG_EXCEPTION(1b)
1:
- popl %es
+ popl %ds
SEG_EXCEPTION(1b)
2:
@@ -295,10 +295,10 @@ SEG_EXCEPTION(1b)
exception_return_to_monitor:
1:
- popl %ds
+ popl %es
SEG_EXCEPTION(1b)
1:
- popl %es
+ popl %ds
SEG_EXCEPTION(1b)
popl %eax
popl %ecx
@@ -363,8 +363,8 @@ __monitor_interrupt:
pushl %edx
pushl %ecx
pushl %eax
- pushl %es
pushl %ds
+ pushl %es
/* compute the address of the monitor context */
call 1f
diff --git common/kqemu_int.h common/kqemu_int.h
index f19f7ca..4b59cb3 100644
Index: common/kqemu_int.h
--- common/kqemu_int.h
+++ common/kqemu_int.h
@@ -367,10 +367,10 @@ struct kqemu_exception_regs {
};
#else
struct kqemu_exception_regs {
- uint16_t ds_sel; /* 0 */
- uint16_t ds_sel_h;
- uint16_t es_sel; /* 1 */
+ uint16_t es_sel; /* 0 */
uint16_t es_sel_h;
+ uint16_t ds_sel; /* 1 */
+ uint16_t ds_sel_h;
uint32_t eax; /* 2 */
uint32_t ecx;
uint32_t edx;
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