[Patch] (big) real mode emulation - jmp rel

Nitin A Kamble
2007-08-10T22:32:37Z

[-- Attachment #1.1.1.1: Type: text/plain, Size: 294 bytes --]

Hi Avi,
The patch to implement "jmp rel" emulation is attached.

Thanks & Regards,
Nitin
Open Source Technology Center, Intel Corporation.
-------------------------------------------------------------------------
The mind is like a parachute; it works much better when it's open.

[-- Attachment #1.1.1.2: Type: text/html, Size: 934 bytes --]

[-- Attachment #1.1.2: jmprel.patch --]
[-- Type: text/x-patch, Size: 1537 bytes --]

commit 1d77b7ad2bcb20858dd66d9653952a8d1cc0a153
Author: Nitin A Kamble <nitin.a.kamble@intel.com>
Date: Fri Aug 10 18:36:12 2007 -0700

Implement instruction "jmp rel" opcode 0xe9

Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com>

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index b4f439c..40fb6ee 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -145,8 +145,10 @@ static u8 opcode_table[256] = {
0, 0, 0, 0,
/* 0xD8 - 0xDF */
0, 0, 0, 0, 0, 0, 0, 0,
- /* 0xE0 - 0xEF */
- 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ /* 0xE0 - 0xE7 */
+ 0, 0, 0, 0, 0, 0, 0, 0,
+ /* 0xE8 - 0xEF */
+ 0, SrcImm|ImplicitOps, 0, 0, 0, 0, 0, 0,
/* 0xF0 - 0xF7 */
0, 0, 0, 0,
ImplicitOps, 0,
@@ -447,6 +449,12 @@ struct operand {
(((reg) + _inc) & ((1UL << (ad_bytes << 3)) - 1)); \
} while (0)

+#define jmp_rel(rel) \
+do { \
+ _eip += (int)(rel); \
+ _eip = ((op_bytes == 2) ? (uint16_t)_eip : (uint32_t)_eip); \
+} while (0)
+
/*
* Given the 'reg' portion of a ModRM byte, and a register block, return a
* pointer into the block that addresses the relevant register.
@@ -1200,6 +1208,10 @@ special_insn:
case 0xae ... 0xaf: /* scas */
DPRINTF("Urk! I don't handle SCAS.\n");
goto cannot_emulate;
+ case 0xe9: /* jmp rel */
+ jmp_rel(src.val);
+ no_wb = 1; /* Disable writeback. */
+ break;
case 0xf4: /* hlt */
ctxt->vcpu->halt_request = 1;
goto done;