Re: [Qemu-devel] [RFC][PATCH] x86: CS limit checks

[Jan Kiszka]

Paul Brook wrote:
> On Thursday 17 July 2008, Jan Kiszka wrote:
>> +    if (s->pc < s->cs_base || s->pc - s->cs_base > s->cs_limit) {
>> +        /* At least some of the opcode fetches violate the CS limit.
>> +           Overwrite the generated code with a GPF raising one. */
>> +        gen_opc_ptr = gen_opc_start;
>> +        gen_opparam_ptr = gen_opparam_start;
>> +        gen_exception(s, EXCP0D_GPF, pc_start - s->cs_base);
>> +    }
> 
> I'm fairly sure this is wrong. The TB may fault before it gets to the end of 
> the segment. Likewise if the instruction spanning the limit happens to be an 
> illegal op you will generate the wrong kind of exception.

What a pity, it looked so easy. OK, will think about those aspects
again. BTW, what happens when the translator hits an unresolvable
address and faults?

Jan

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