Re: [Nasm-devel] [nasm:master] disasm: Fix for disassembly of BOUND

[Mark S. <na...@ms...>]

On 4 Nov 2015, at 19:30, Cyrill Gorcunov wrote:

> On Wed, Nov 04, 2015 at 10:51:36AM -0800, H. Peter Anvin wrote:
>>> 
>>> Signed-off-by: Mark Scott <na...@ms...>
>>> Signed-off-by: Cyrill Gorcunov <gor...@gm...>
>>> 
>> 
>> This is wrong, though; EVEX is permitted in 32-bit mode just as VEX is.
>> 
>> The key thing is that bits [7:5] have to be 1 in 32-bit mode.  It is
>> unclear what happens if these bits are 110 as that depends on if it is
>> decoded using the modr/m decoder or not.  For VEX prefixes we accept
>> them as VEX in that case, which may not match the CPU.
>> 
>> The evex_p0 test seems to have been taken out of thin air; I don't think
>> that is a requirement for EVEX.
>> 
>> So, I believe the logic should in fact be the exactly same logic that we
>> have for VEX:
>> 
>>            if (segsize == 64 || (data[1] & 0xc0) == 0xc0) {
> 
> Ah, good point! Thanks for clarification, Peter! I'll fix
> 

Apologies for the mistake, and thanks for spotting!

Mark