Re: [Qemu-devel] [PATCH] x86: Fixed incorrect segment base address addition

[Vitaly Chipounov <vitaly.chipounov@epfl.ch>]

Max,

On 02.07.2012 17:18, Max Filippov wrote:
> On Mon, Jul 2, 2012 at 2:29 PM, Vitaly Chipounov
> <vitaly.chipounov@epfl.ch> wrote:
>> An instruction with address and segment size override triggers the bug.
>> inc dword ptr gs:260h[ebx*4] gets incorrectly translated to:
>> (uint32_t)(gs.base + ebx * 4 + 0x260)
>> instead of
>> gs.base + (uint32_t)(ebx * 4 + 0x260)
> Do I understand it right that this fixes address calculation for
> 64-bit mode but breaks it for compatibility mode?

You are right, it indeed breaks compatibility mode. Thanks for the
reference from the Intel manual.

I will send an updated patch.

Vitaly

>> Signed-off-by: Vitaly Chipounov <vitaly.chipounov@epfl.ch>
>> ---
>>  target-i386/translate.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/target-i386/translate.c b/target-i386/translate.c
>> index a902f4a..9ca7375 100644
>> --- a/target-i386/translate.c
>> +++ b/target-i386/translate.c
>> @@ -459,10 +459,10 @@ static inline void gen_op_movl_A0_seg(int reg)
>>  static inline void gen_op_addl_A0_seg(int reg)
>>  {
>>      tcg_gen_ld_tl(cpu_tmp0, cpu_env, offsetof(CPUX86State, segs[reg].base));
>> -    tcg_gen_add_tl(cpu_A0, cpu_A0, cpu_tmp0);
>>  #ifdef TARGET_X86_64
>>      tcg_gen_andi_tl(cpu_A0, cpu_A0, 0xffffffff);
>>  #endif
>> +    tcg_gen_add_tl(cpu_A0, cpu_A0, cpu_tmp0);
>>  }
>>
>>  #ifdef TARGET_X86_64
>> --
>> 1.7.4.1
>>
>>
>
>