On 07/19/2012 01:51 PM, Gleb Natapov wrote:
>> > +int x86_linearize(struct x86_linearize_params *p, ulong *linear)
>> > {
>> > - struct desc_struct desc;
>> > - bool usable;
>> > ulong la;
>> > u32 lim;
>> > - u16 sel;
>> > unsigned cpl, rpl;
>> >
>> > - la = seg_base(ctxt, addr.seg) + addr.ea;
>> > - switch (ctxt->mode) {
>> > + la = get_desc_base(&p->desc) + p->ea;
>>
>> This makes 64-bit mode slower, since before the patch it avoided reading
>> the segment base for non-fs/gs segments, and only read the segment base
>> for fs/gs. After the patch we always execute 4 VMREADs (and decode the
>> results).
>>
> That's easy to fix by making caller prepare fake desc if mode is 64-bit
> and segment is non-fs/gs. The question is if this even measurable?
I'm sure it will be measurable, esp. on older processors. Why not
measure it?
--
error compiling committee.c: too many arguments to function
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