[Xen-changelog] [xen staging] x86emul: vendor specific near indirect branch behavior in 64-bit mode

[patchbot@xxxxxxx]

commit a965d9fab2719753f8699d6ce9062e842c315c30
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Mar 26 12:34:16 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Mar 26 12:34:16 2020 +0100

    x86emul: vendor specific near indirect branch behavior in 64-bit mode
    
    Intel CPUs ignore operand size overrides here, while AMD ones don't.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 tools/tests/x86_emulator/test_x86_emulator.c | 11 +++++++++++
 xen/arch/x86/x86_emulate/x86_emulate.c       |  9 +++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/tools/tests/x86_emulator/test_x86_emulator.c 
b/tools/tests/x86_emulator/test_x86_emulator.c
index 2d39bd05db..63191dfd09 100644
--- a/tools/tests/x86_emulator/test_x86_emulator.c
+++ b/tools/tests/x86_emulator/test_x86_emulator.c
@@ -813,6 +813,17 @@ static const struct {
         .opcode = { 0x66, 0x67, 0xe3, 0x10 },
         .opc_len = { 4, 4 },
         .disp = { 4 + 16 - MMAP_ADDR, 4 + 16 },
+    }, {
+        .descr = "jmpw *(%rsp)",
+        .opcode = { 0x66, 0xff, 0x24, 0x24 },
+        .opc_len = { 4, 4 },
+        .disp = { STKVAL_DISP - MMAP_ADDR, STKVAL_DISP },
+    }, {
+        .descr = "callw *(%rsp)",
+        .opcode = { 0x66, 0xff, 0x14, 0x24 },
+        .opc_len = { 4, 4 },
+        .stkoff = { -2, -8 },
+        .disp = { STKVAL_DISP - MMAP_ADDR, STKVAL_DISP },
     },
 };
 #endif
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 49c21585c2..1ecdf5315a 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -2523,8 +2523,7 @@ x86_decode_onebyte(
         {
         case 2: /* call (near) */
         case 4: /* jmp (near) */
-        case 6: /* push */
-            if ( mode_64bit() && op_bytes == 4 )
+            if ( mode_64bit() && (op_bytes == 4 || !amd_like(ctxt)) )
                 op_bytes = 8;
             state->desc = DstNone | SrcMem | Mov;
             break;
@@ -2536,6 +2535,12 @@ x86_decode_onebyte(
                 op_bytes = 4;
             state->desc = DstNone | SrcMem | Mov;
             break;
+
+        case 6: /* push */
+            if ( mode_64bit() && op_bytes == 4 )
+                op_bytes = 8;
+            state->desc = DstNone | SrcMem | Mov;
+            break;
         }
         break;
     }
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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