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Re: [Qemu-devel] [PATCH] target-i386: Fix aflag logic for CODE64 and the
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] target-i386: Fix aflag logic for CODE64 and the 0x67 prefix |
Date: |
Fri, 31 May 2013 17:04:34 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 |
Il 31/05/2013 17:03, Richard Henderson ha scritto:
> Ping.
>
> On 05/29/2013 12:30 PM, Richard Henderson wrote:
>> The code reorganization in commit 4a6fd938 broke handling of PREFIX_ADR.
>> While fixing this, tidy and comment the code so that it's more obvious
>> what's going on in setting both aflag and dflag.
>>
>> The TARGET_X86_64 ifdef can be eliminated because CODE64 expands to the
>> constant zero when TARGET_X86_64 is undefined.
>>
>> Cc: Paolo Bonzini <address@hidden>
>> Reported-by: Laszlo Ersek <address@hidden>
>> Signed-off-by: Richard Henderson <address@hidden>
>> ---
>> target-i386/translate.c | 30 +++++++++++++++---------------
>> 1 file changed, 15 insertions(+), 15 deletions(-)
>>
>> diff --git a/target-i386/translate.c b/target-i386/translate.c
>> index 0aeccdb..14b0298 100644
>> --- a/target-i386/translate.c
>> +++ b/target-i386/translate.c
>> @@ -4677,8 +4677,6 @@ static target_ulong disas_insn(CPUX86State *env,
>> DisasContext *s,
>> }
>> s->pc = pc_start;
>> prefixes = 0;
>> - aflag = s->code32;
>> - dflag = s->code32;
>> s->override = -1;
>> rex_w = -1;
>> rex_r = 0;
>> @@ -4801,23 +4799,25 @@ static target_ulong disas_insn(CPUX86State *env,
>> DisasContext *s,
>> }
>>
>> /* Post-process prefixes. */
>> - if (prefixes & PREFIX_DATA) {
>> - dflag ^= 1;
>> - }
>> - if (prefixes & PREFIX_ADR) {
>> - aflag ^= 1;
>> - }
>> -#ifdef TARGET_X86_64
>> if (CODE64(s)) {
>> - if (rex_w == 1) {
>> - /* 0x66 is ignored if rex.w is set */
>> - dflag = 2;
>> + /* In 64-bit mode, the default data size is 32-bit. Select 64-bit
>> + data with rex_w, and 16-bit data with 0x66; rex_w takes
>> precedence
>> + over 0x66 if both are present. */
>> + dflag = (rex_w > 0 ? 2 : prefixes & PREFIX_DATA ? 0 : 1);
>> + /* In 64-bit mode, 0x67 selects 32-bit addressing. */
>> + aflag = (prefixes & PREFIX_ADR ? 1 : 2);
>> + } else {
>> + /* In 16/32-bit mode, 0x66 selects the opposite data size. */
>> + dflag = s->code32;
>> + if (prefixes & PREFIX_DATA) {
>> + dflag ^= 1;
>> }
>> - if (!(prefixes & PREFIX_ADR)) {
>> - aflag = 2;
>> + /* In 16/32-bit mode, 0x67 selects the opposite addressing. */
>> + aflag = s->code32;
>> + if (prefixes & PREFIX_ADR) {
>> + aflag ^= 1;
>> }
Reviewed-by: Paolo Bonzini <address@hidden>
Cc: address@hidden
>> }
>> -#endif
>>
>> s->prefix = prefixes;
>> s->aflag = aflag;
>>
>