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Re: Bug in i386_process_record?
On Sun, Aug 23, 2009 at 12:29, Hui Zhu<teawater@gmail.com> wrote:
> On Sun, Aug 23, 2009 at 12:07, Michael Snyder<msnyder@vmware.com> wrote:
>> Hui Zhu wrote:
>>>
>>> On Sun, Aug 23, 2009 at 11:07, Michael Snyder<msnyder@vmware.com> wrote:
>>>>
>>>> Hi, please *don't* check this in -- I found a problem with it.
>>>>
>>>> Try running it with "set debug record 1" during the recording pass.
>>>>
>>>> I see a whole lot of these:
>>>>
>>>> Process record ignores the memory change of instruction at address
>>>> 0x0x587be9 because it can't get the value of the segment register.
>>>
>>>
>>> Hi Michael,
>>>
>>> Most of the string ops instruction will use segment register.
>>> But I check the some linux program that have string ops insn. ?I found
>>> that in linux (maybe glibc), the value of the segment register is 0,
>>> so it will not affect anything.
>>
>> Hmm, ok, but this is i386-tdep.c, not i386-linux-tdep.c...
>>
>>> And in linux user level, looks we don't have any good way to get the
>>> value of the segment register.
>>>
>>> So I think this patch is OK.
>>
>> I see -- so, we don't really "ignore" the memory change at all.
>>
>> Isn't the message misleading, then?
>>
>> What about something like:
>>
>> @@ -4458,11 +4458,12 @@ reswitch:
>> ? ? ? ? ? if (ir.aflag)
>> ? ? ? ? ? ? {
>> ? ? ? ? ? ? ? /* addr += ((uint32_t) read_register (I386_ES_REGNUM)) << 4;
>> */
>> - ? ? ? ? ? ? ?if (record_debug)
>> - ? ? ? ? ? ? ? ?printf_unfiltered (_("Process record ignores the memory
>> change "
>> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "of instruction at address 0x%s
>> because "
>> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "it can't get the value of the segment
>> "
>> - ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "register.\n"),
>> + ? ? ? ? ? ? ?if (record_debug &&
>> + ? ? ? ? ? ? ? ? read_register (I386_ES_REGNUM) != 0)
>> + ? ? ? ? ? ? ? ?printf_unfiltered (_("Process record ignores value of ES "
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "register for instruction at address
>> %s "
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "because "it can't get the value of "
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? "the segment register.\n"),
>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?paddress (gdbarch, ir.addr));
>> ? ? ? ? ? ? }
>> ? ? ? ? ? if (prefixes & (PREFIX_REPZ | PREFIX_REPNZ))
>>
>
> read_register (I386_ES_REGNUM)
> This value is not the value of ES. ?This is number of TLB. ?So ....
>
> Hui
>
ES is one of the segment register.
Hui