[Xen-changelog] [xen-unstable] [XEN][EMUL] x86 emulator should support 32-bit offsets in real mode.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxxxx
# Node ID 869937819ed95ead0468a6c64b4aa753a4b8ab76
# Parent  9158ecb9045fd533f602378adb4abe41947ef781
[XEN][EMUL] x86 emulator should support 32-bit offsets in real mode.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 xen/arch/x86/x86_emulate.c |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)

diff -r 9158ecb9045f -r 869937819ed9 xen/arch/x86/x86_emulate.c
--- a/xen/arch/x86/x86_emulate.c        Tue Jun 27 09:54:05 2006 +0100
+++ b/xen/arch/x86/x86_emulate.c        Tue Jun 27 10:36:51 2006 +0100
@@ -374,9 +374,8 @@ do{ __asm__ __volatile__ (              
 
 /* Access/update address held in a register, based on addressing mode. */
 #define register_address(sel, reg)                                      \
-    ((ad_bytes == sizeof(unsigned long)) ? (reg) :                      \
-     ((mode == X86EMUL_MODE_REAL) ? /* implies ad_bytes == 2 */         \
-      (((unsigned long)(sel) << 4) + ((reg) & 0xffff)) :                \
+    (((mode == X86EMUL_MODE_REAL) ? ((unsigned long)(sel) << 4) : 0) +  \
+     ((ad_bytes == sizeof(unsigned long)) ? (reg) :                     \
       ((reg) & ((1UL << (ad_bytes << 3)) - 1))))
 #define register_address_increment(reg, inc)                            \
 do {                                                                    \
@@ -510,10 +509,6 @@ x86_emulate_memop(
     }
  done_prefixes:
 
-    /* Note quite the same as 80386 real mode, but hopefully good enough. */
-    if ( (mode == X86EMUL_MODE_REAL) && (ad_bytes != 2) )
-        goto cannot_emulate;
-
     /* REX prefix. */
     if ( (mode == X86EMUL_MODE_PROT64) && ((b & 0xf0) == 0x40) )
     {

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