[Xen-changelog] [xen master] x86emul: introduce SrcEax for XCHG

[patchbot@xxxxxxx]

commit c826567bbcf8f32cd9c08ba74cbcd29b60ad80d2
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Aug 17 15:34:26 2016 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Aug 17 15:34:26 2016 +0200

    x86emul: introduce SrcEax for XCHG
    
    Just like said in commit c0bc0adf24 ("x86emul: use DstEax where
    possible"): While it avoids just a few instructions, we should
    nevertheless make use of generic code as much as possible. Here we can
    arrange for that by simply introducing SrcEax (which requires no other
    code adjustments).
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 2b59a47..cef7bee 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -34,6 +34,7 @@
 #define SrcNone     (0<<3) /* No source operand. */
 #define SrcImplicit (0<<3) /* Source operand is implicit in the opcode. */
 #define SrcReg      (1<<3) /* Register operand. */
+#define SrcEax      SrcReg /* Register EAX (aka SrcReg with no ModRM) */
 #define SrcMem      (2<<3) /* Memory operand. */
 #define SrcMem16    (3<<3) /* Memory operand (16-bit). */
 #define SrcImm      (4<<3) /* Immediate operand. */
@@ -118,8 +119,10 @@ static uint8_t opcode_table[256] = {
     DstMem|SrcReg|ModRM|Mov, DstReg|SrcNone|ModRM,
     DstReg|SrcMem16|ModRM|Mov, DstMem|SrcNone|ModRM|Mov,
     /* 0x90 - 0x97 */
-    ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
-    ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
+    DstImplicit|SrcEax, DstImplicit|SrcEax,
+    DstImplicit|SrcEax, DstImplicit|SrcEax,
+    DstImplicit|SrcEax, DstImplicit|SrcEax,
+    DstImplicit|SrcEax, DstImplicit|SrcEax,
     /* 0x98 - 0x9F */
     ImplicitOps, ImplicitOps, ImplicitOps, ImplicitOps,
     ImplicitOps|Mov, ImplicitOps|Mov, ImplicitOps, ImplicitOps,
@@ -2501,12 +2504,11 @@ x86_emulate(
     case 0x90: /* nop / xchg %%r8,%%rax */
         if ( !(rex_prefix & 1) )
             break; /* nop */
+        /* fall through */
 
     case 0x91 ... 0x97: /* xchg reg,%%rax */
-        src.type = dst.type = OP_REG;
-        src.bytes = dst.bytes = op_bytes;
-        src.reg  = (unsigned long *)&_regs.eax;
-        src.val  = *src.reg;
+        dst.type = OP_REG;
+        dst.bytes = op_bytes;
         dst.reg  = decode_register(
             (b & 7) | ((rex_prefix & 1) << 3), &_regs, 0);
         dst.val  = *dst.reg;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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