* [PATCH] x86emul: introduce SrcEax for XCHG
@ 2016-08-16 13:51 Jan Beulich
2016-08-16 14:32 ` Andrew Cooper
0 siblings, 1 reply; 4+ messages in thread
From: Jan Beulich @ 2016-08-16 13:51 UTC (permalink / raw)
To: xen-devel; +Cc: Andrew Cooper
[-- Attachment #1: Type: text/plain, Size: 2113 bytes --]
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@suse.com>
--- 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,
@@ -2491,12 +2494,11 @@ 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;
[-- Attachment #2: x86emul-use-SrcEax-xchg.patch --]
[-- Type: text/plain, Size: 2145 bytes --]
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@suse.com>
--- 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,
@@ -2491,12 +2494,11 @@ 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;
[-- Attachment #3: Type: text/plain, Size: 127 bytes --]
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86emul: introduce SrcEax for XCHG
2016-08-16 13:51 [PATCH] x86emul: introduce SrcEax for XCHG Jan Beulich
@ 2016-08-16 14:32 ` Andrew Cooper
2016-08-16 14:50 ` Jan Beulich
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Cooper @ 2016-08-16 14:32 UTC (permalink / raw)
To: Jan Beulich, xen-devel
On 16/08/16 14:51, Jan Beulich wrote:
> 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@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citirx.com>
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86emul: introduce SrcEax for XCHG
2016-08-16 14:32 ` Andrew Cooper
@ 2016-08-16 14:50 ` Jan Beulich
2016-08-16 14:52 ` Andrew Cooper
0 siblings, 1 reply; 4+ messages in thread
From: Jan Beulich @ 2016-08-16 14:50 UTC (permalink / raw)
To: Andrew Cooper; +Cc: xen-devel
>>> On 16.08.16 at 16:32, <andrew.cooper3@citrix.com> wrote:
> On 16/08/16 14:51, Jan Beulich wrote:
>> 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@suse.com>
>
> Reviewed-by: Andrew Cooper <andrew.cooper3@citirx.com>
I'll take the liberty to correct the typo, to aid Lars' stats collection.
Jan
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86emul: introduce SrcEax for XCHG
2016-08-16 14:50 ` Jan Beulich
@ 2016-08-16 14:52 ` Andrew Cooper
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Cooper @ 2016-08-16 14:52 UTC (permalink / raw)
To: Jan Beulich; +Cc: xen-devel
On 16/08/16 15:50, Jan Beulich wrote:
>>>> On 16.08.16 at 16:32, <andrew.cooper3@citrix.com> wrote:
>> On 16/08/16 14:51, Jan Beulich wrote:
>>> 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@suse.com>
>> Reviewed-by: Andrew Cooper <andrew.cooper3@citirx.com>
> I'll take the liberty to correct the typo, to aid Lars' stats collection.
Oops yes. Sorry about that.
~Andrew
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-08-16 13:51 [PATCH] x86emul: introduce SrcEax for XCHG Jan Beulich
2016-08-16 14:32 ` Andrew Cooper
2016-08-16 14:50 ` Jan Beulich
2016-08-16 14:52 ` Andrew Cooper
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