Gleb Natapov wrote:
> On Wed, Apr 14, 2010 at 02:11:39PM +0200, Jan Kiszka wrote:
>> static int emulator_do_task_switch(struct x86_emulate_ctxt *ctxt,
>> - struct x86_emulate_ops *ops,
>> - u16 tss_selector, int reason)
>> + struct x86_emulate_ops *ops,
>> + u16 tss_selector, int reason,
>> + bool has_error_code, u32 error_code)
>> {
>> struct desc_struct curr_tss_desc, next_tss_desc;
>> int ret;
>> @@ -2416,12 +2417,23 @@ static int emulator_do_task_switch(struct
>> x86_emulate_ctxt *ctxt,
>> ops->set_cached_descriptor(&next_tss_desc, VCPU_SREG_TR, ctxt->vcpu);
>> ops->set_segment_selector(tss_selector, VCPU_SREG_TR, ctxt->vcpu);
>>
>> + if (ret == X86EMUL_CONTINUE && has_error_code) {
> It looks like we shouldn't get here if ret != X86EMUL_CONTINUE in the
> first place. This check should be done just after call to
> task_switch_16/32. Not directly related to your patch, but still...
Will do this in a preparational patch.
>
>> @@ -2416,12 +2417,23 @@ static int emulator_do_task_switch(struct
>> x86_emulate_ctxt *ctxt,
>> ops->set_cached_descriptor(&next_tss_desc, VCPU_SREG_TR,
>> ctxt->vcpu);
>> ops->set_segment_selector(tss_selector, VCPU_SREG_TR,
>> ctxt->vcpu);
>>
>> + if (ret == X86EMUL_CONTINUE && has_error_code) {
>> + struct decode_cache *c = &ctxt->decode;
>> +
>> + c->op_bytes = c->ad_bytes = (next_tss_desc.type & 8) ? 4
>> : 2;
>> + c->lock_prefix = 0;
>> + c->src.val = (unsigned long) error_code;
>> + emulate_push(ctxt);
>> + ret = writeback(ctxt, ops);
>> + }
> I would move writeback() to emulator_task_switch(). Just make
> c->dst.type = OP_NONE if writeback is not needed.
I should dramatically increase the overhead for the common case. :)
Yeah, can do so if preferred.
Thanks,
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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