Re: Bug in i386_process_record?

[Hui Zhu <teawater at gmail dot com>]

On Thu, Aug 27, 2009 at 09:43, Hui Zhu<teawater@gmail.com> wrote:
> On Thu, Aug 27, 2009 at 08:28, Michael Snyder<msnyder@vmware.com> wrote:
>> Michael Snyder 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!
>>
>> Hui,
>>
>> Do you think you could add some new tests to i386-reverse.exp,
>> to verify the string instructions?
>>
>> Thanks,
>> Michael
>>
>
> OK. I will do it.
>
> Thanks,
> Hui
>

Hi Michael,

I make a patch to add the test for string insn.

Please help me review it.

Thanks,
Hui

2009-08-27  Hui Zhu  <teawater@gmail.com>

	* gdb.reverse/i386-reverse.c (string_insn_tests): New function.
	(main): Call "string_insn_tests".

---
 testsuite/gdb.reverse/i386-reverse.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/testsuite/gdb.reverse/i386-reverse.c
+++ b/testsuite/gdb.reverse/i386-reverse.c
@@ -38,9 +38,25 @@ inc_dec_tests (void)
   asm ("dec %edi");
 } /* end inc_dec_tests */

+void
+string_insn_tests (void)
+{
+  register char x asm("ax");
+  char *dstp = (char *) 1;
+  int d0;
+  int len = 0;
+
+  asm volatile("rep\n"
+	       "stosb" /* %0, %2, %3 */ :
+	       "=D" (dstp), "=c" (d0) :
+	       "0" (dstp), "1" (len), "a" (x) :
+	       "memory");
+}
+
 int
 main ()
 {
   inc_dec_tests ();
+  string_insn_tests ();
   return 0;	/* end of main */
 }

Attachment: prec-testsuite-string-insn.txt
Description: Text document