Bug in i386_process_record?
Hui Zhu
teawater@gmail.com
Sat Aug 29 06:51:00 GMT 2009
On Thu, Aug 27, 2009 at 07:45, Michael Snyder<msnyder@vmware.com> wrote:
> Hui Zhu wrote:
>>
>> On Wed, Aug 26, 2009 at 02:42, Eli Zaretskii<eliz@gnu.org> wrote:
>>>>
>>>> From: Hui Zhu <teawater@gmail.com>
>>>> Date: Tue, 25 Aug 2009 13:02:44 +0800
>>>> Cc: msnyder@vmware.com, gdb-patches@sourceware.org
>>>>
>>>> It seems that the segment (It is not the section) registers in x86
>>>> protect mode is just help MMU to get the physical address. It's
>>>> transparent for the user level program.
>>>
>>> It's transparent if $es and $ds have the same value (which they
>>> usually do, AFAIK).
>>>
>>>> What do you think about remove this warning from this patch?
>>>
>>> I would indeed do that, if we find that $es and $ds have the same
>>> values. Assuming that someone who knows Linux better than I do
>>> confirms that these two registers hold the same selector when a normal
>>> application is running in user mode.
>>>
>>
>> Thanks for remind me. We cannot get the value of each segment
>> register, but we can get each segment register point to. So if the
>> value of segment registers, it's means that the value of them is same.
>>
>> I add some code about it:
>> regcache_raw_read_unsigned (ir.regcache,
>> ir.regmap[X86_RECORD_ES_REGNUM],
>> &es);
>> regcache_raw_read_unsigned (ir.regcache,
>> ir.regmap[X86_RECORD_DS_REGNUM],
>> &ds);
>> if (ir.aflag && (es != ds))
>> {
>>
>> After that, we will not get the warning because the es is same with ds
>> in user level.
>>
>> What do you think about it?
>
> I think it is the best version I have seen so far.
> And it seems to follow the conclusions of the discussion.
> And I've tested it, and it seems to work.
>
> I would say wait until end-of-business Friday, and
> if there are no more comments, check it in!
>
Checked in.
Thanks,
Hui
>
>
>
>> 2009-08-26 Hui Zhu <teawater@gmail.com>
>>
>> * i386-tdep.c (i386_process_record): Fix the error of string
>> ops instructions's handler.
>> ---
>> i386-tdep.c | 69
>> ++++++++++++++++++++++++++++--------------------------------
>> 1 file changed, 33 insertions(+), 36 deletions(-)
>>
>> --- a/i386-tdep.c
>> +++ b/i386-tdep.c
>> @@ -4441,50 +4441,47 @@ reswitch:
>> /* insS */
>> case 0x6c:
>> case 0x6d:
>> - if ((opcode & 1) == 0)
>> - ir.ot = OT_BYTE;
>> - else
>> - ir.ot = ir.dflag + OT_WORD;
>> regcache_raw_read_unsigned (ir.regcache,
>> - ir.regmap[X86_RECORD_REDI_REGNUM],
>> + ir.regmap[X86_RECORD_RECX_REGNUM],
>> &tmpulongest);
>> - if (!ir.aflag)
>> - {
>> - tmpulongest &= 0xffff;
>> - /* 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"),
>> - paddress (gdbarch, ir.addr));
>> - }
>> - if (prefixes & (PREFIX_REPZ | PREFIX_REPNZ))
>> + if (tmpulongest)
>> {
>> - ULONGEST count, eflags;
>> + ULONGEST es, ds;
>> +
>> + if ((opcode & 1) == 0)
>> + ir.ot = OT_BYTE;
>> + else
>> + ir.ot = ir.dflag + OT_WORD;
>> regcache_raw_read_unsigned (ir.regcache,
>> ir.regmap[X86_RECORD_REDI_REGNUM],
>> - &count);
>> - if (!ir.aflag)
>> - count &= 0xffff;
>> + &tmpulongest);
>> +
>> regcache_raw_read_unsigned (ir.regcache,
>> -
>> ir.regmap[X86_RECORD_EFLAGS_REGNUM],
>> - &eflags);
>> - if ((eflags >> 10) & 0x1)
>> - tmpulongest -= (count - 1) * (1 << ir.ot);
>> - if (record_arch_list_add_mem (tmpulongest, count * (1 <<
>> ir.ot)))
>> - return -1;
>> - I386_RECORD_ARCH_LIST_ADD_REG (X86_RECORD_RECX_REGNUM);
>> - }
>> - else
>> - {
>> + ir.regmap[X86_RECORD_ES_REGNUM],
>> + &es);
>> + regcache_raw_read_unsigned (ir.regcache,
>> + ir.regmap[X86_RECORD_DS_REGNUM],
>> + &ds);
>> + if (ir.aflag && (es != ds))
>> + {
>> + /* 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 "
>> + "ES segment register.\n"),
>> + paddress (gdbarch, ir.addr));
>> + }
>> +
>> + if (prefixes & (PREFIX_REPZ | PREFIX_REPNZ))
>> + I386_RECORD_ARCH_LIST_ADD_REG (X86_RECORD_RECX_REGNUM);
>> if (record_arch_list_add_mem (tmpulongest, 1 << ir.ot))
>> return -1;
>> - }
>> - if (opcode == 0xa4 || opcode == 0xa5)
>> - I386_RECORD_ARCH_LIST_ADD_REG (X86_RECORD_RESI_REGNUM);
>> - I386_RECORD_ARCH_LIST_ADD_REG (X86_RECORD_REDI_REGNUM);
>> - I386_RECORD_ARCH_LIST_ADD_REG (X86_RECORD_EFLAGS_REGNUM);
>> + if (opcode == 0xa4 || opcode == 0xa5)
>> + I386_RECORD_ARCH_LIST_ADD_REG (X86_RECORD_RESI_REGNUM);
>> + I386_RECORD_ARCH_LIST_ADD_REG (X86_RECORD_REDI_REGNUM);
>> + I386_RECORD_ARCH_LIST_ADD_REG (X86_RECORD_EFLAGS_REGNUM);
>> + }
>> break;
>>
>> /* cmpsS */
>
>
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