25.04.2014, 21:09, "Richard Henderson" <r...@twiddle.net>:
> On 04/25/2014 01:13 AM, Dmitry Poletaev wrote:
>> There is a set of test, that checks QEMU CPU for similar behavior with
>> real hardware (http://roberto.greyhats.it/projects/pills.html). Test
>> reg/pill2579.c can detect, that program is execute in emulated environment.
>> It is related with behavior of rcl instruction. If the number of shifted
>> bits more than 1, OF of eflags become undefined. Real CPUs does not change
>> OF, if it is undefined. QEMU do it anyway.
>> Emulated program can execute that test and after that can understand
>> environment not real.
>>
>> Signed-off-by: Dmitry Poletaev <poletaev-q...@yandex.ru>
>>
>> diff --git a/target-i386/shift_helper_template.h
>> b/target-i386/shift_helper_template.h
>> index cf91a2d..d5bd321 100644
>> --- a/target-i386/shift_helper_template.h
>> +++ b/target-i386/shift_helper_template.h
>> @@ -64,8 +64,10 @@ target_ulong glue(helper_rcl, SUFFIX)(CPUX86State *env,
>> target_ulong t0,
>> }
>> t0 = res;
>> env->cc_src = (eflags & ~(CC_C | CC_O)) |
>> - (lshift(src ^ t0, 11 - (DATA_BITS - 1)) & CC_O) |
>> ((src >> (DATA_BITS - count)) & CC_C);
>> + if (count == 1) {
>> + env->cc_src |= (lshift(src ^ t0, 11 - (DATA_BITS - 1)) &
>> CC_O);
>> + }
> This doesn't do what you say it does. It doesn't leave O unchanged,
> it always resets it to 0, and only sets it back to 1 if count == 1.
>
> r~
Of course, you are right. It is more correct now.
Signed-off-by: Dmitry Poletaev <poletaev-q...@yandex.ru>
diff --git a/target-i386/shift_helper_template.h
b/target-i386/shift_helper_template.h
index cf91a2d..4fcdc19 100644
--- a/target-i386/shift_helper_template.h
+++ b/target-i386/shift_helper_template.h
@@ -63,9 +63,11 @@ target_ulong glue(helper_rcl, SUFFIX)(CPUX86State *env,
target_ulong t0,
res |= t0 >> (DATA_BITS + 1 - count);
}
t0 = res;
- env->cc_src = (eflags & ~(CC_C | CC_O)) |
- (lshift(src ^ t0, 11 - (DATA_BITS - 1)) & CC_O) |
+ env->cc_src = (eflags & ~CC_C) |
((src >> (DATA_BITS - count)) & CC_C);
+ if (count == 1) {
+ env->cc_src |= (lshift(src ^ t0, 11 - (DATA_BITS - 1)) & CC_O);
+ }
}
return t0;
}
@@ -93,9 +95,11 @@ target_ulong glue(helper_rcr, SUFFIX)(CPUX86State *env,
target_ulong t0,
res |= t0 << (DATA_BITS + 1 - count);
}
t0 = res;
- env->cc_src = (eflags & ~(CC_C | CC_O)) |
- (lshift(src ^ t0, 11 - (DATA_BITS - 1)) & CC_O) |
+ env->cc_src = (eflags & ~CC_C) |
((src >> (count - 1)) & CC_C);
+ if (count == 1) {
+ env->cc_src |= (lshift(src ^ t0, 11 - (DATA_BITS - 1)) & CC_O);
+ }
}
return t0;
}
