[Xen-changelog] [xen-unstable] x86/emul: only emulate possibly operand sizes for POPA

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Jan Beulich <jbeulich@xxxxxxxx>
# Date 1352368352 -3600
# Node ID aa2074529eb0183257b6f5f29821b0cd6dfd991a
# Parent  bd78e5630a5be55d439eb235627d52ebe8214524
x86/emul: only emulate possibly operand sizes for POPA

This opcode neither supports 1-byte operands, nor does it support
8-byte ones (since the opcode is undefined in 64-bit mode). Simplify
the code accordingly.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Keir Fraser <keir@xxxxxxx>
---


diff -r bd78e5630a5b -r aa2074529eb0 xen/arch/x86/x86_emulate/x86_emulate.c
--- a/xen/arch/x86/x86_emulate/x86_emulate.c    Fri Nov 02 17:15:30 2012 +0100
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c    Thu Nov 08 10:52:32 2012 +0100
@@ -1996,13 +1996,10 @@ x86_emulate(
             if ( (rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes),
                                   &dst.val, op_bytes, ctxt, ops)) != 0 )
                 goto done;
-            switch ( op_bytes )
-            {
-            case 1: *(uint8_t  *)regs[i] = (uint8_t)dst.val; break;
-            case 2: *(uint16_t *)regs[i] = (uint16_t)dst.val; break;
-            case 4: *regs[i] = (uint32_t)dst.val; break; /* 64b: zero-ext */
-            case 8: *regs[i] = dst.val; break;
-            }
+            if ( op_bytes == 2 )
+                *(uint16_t *)regs[i] = (uint16_t)dst.val;
+            else
+                *regs[i] = dst.val; /* 64b: zero-ext done by read_ulong() */
         }
         break;
     }

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