From: Hui Zhu <teawater@gmail.com>
To: Michael Snyder <msnyder@vmware.com>
Cc: gdb-patches ml <gdb-patches@sourceware.org>
Subject: Re: Bug in i386_process_record?
Date: Tue, 11 Aug 2009 18:31:00 -0000 [thread overview]
Message-ID: <daef60380908102319k56787d57w49ea1cf4ed338584@mail.gmail.com> (raw)
In-Reply-To: <4A8097B4.2080709@vmware.com>
[-- Attachment #1: Type: text/plain, Size: 4521 bytes --]
On Tue, Aug 11, 2009 at 05:57, Michael Snyder <msnyder@vmware.com> wrote:
>
> Yes, this seems to be better. It records only 4 bytes each time
> it is called.
>
> But there seems to be still an off-by-one error? With the test
> program that I provided, we call memset with an argument of
> 1024, but we actually record 1025 bytes... this code gets hit
> 257 times, with the last time recording only 1 byte.
>
>
Hi Michael,
This issue is because:
0xb7edf4e7 <memset+55>: rep stos %eax,%es:(%edi)
0xb7edf4e9 <memset+57>: mov %edx,%ecx
0xb7edf4eb <memset+59>: rep stos %al,%es:(%edi)
0xb7edf4ed <memset+61>: mov 0x8(%esp),%eax
0xb7edf4f1 <memset+65>: pop %edi
If the memcpy size is not align with 4, it will handle by second rep stos.
Then rep stos will not execute if %ecx is 0.
i386_process_record doesn't check %ecx, so it get this error.
I make a new patch for it. Please help me review it.
Thanks,
Hui
2009-08-11 Hui Zhu <teawater@gmail.com>
* record.c (i386_process_record): Remove some error code.
---
i386-tdep.c | 61 +++++++++++++++++++++++-------------------------------------
1 file changed, 24 insertions(+), 37 deletions(-)
--- a/i386-tdep.c
+++ b/i386-tdep.c
@@ -4441,50 +4441,37 @@ 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;
+ 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;
- 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
- {
+ &tmpulongest);
+ 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"),
+ 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 */
[-- Attachment #2: prec-fix-x86-strinsn.txt --]
[-- Type: text/plain, Size: 3380 bytes --]
---
i386-tdep.c | 61 +++++++++++++++++++++++-------------------------------------
1 file changed, 24 insertions(+), 37 deletions(-)
--- a/i386-tdep.c
+++ b/i386-tdep.c
@@ -4441,50 +4441,37 @@ 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;
+ 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;
- 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
- {
+ &tmpulongest);
+ 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"),
+ 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 */
next prev parent reply other threads:[~2009-08-11 6:20 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4A7BA1DE.6010103@vmware.com>
2009-08-10 9:33 ` Hui Zhu
2009-08-10 22:12 ` Michael Snyder
2009-08-11 6:20 ` Hui Zhu
2009-08-11 18:31 ` Hui Zhu [this message]
2009-08-16 16:12 ` Hui Zhu
2009-08-18 5:35 ` Michael Snyder
2009-08-18 11:52 ` Hui Zhu
2009-08-21 3:23 ` Hui Zhu
2009-08-23 3:15 ` Michael Snyder
2009-08-23 3:33 ` Hui Zhu
2009-08-23 4:13 ` Michael Snyder
2009-08-23 9:04 ` Hui Zhu
2009-08-23 17:37 ` Hui Zhu
2009-08-23 18:23 ` Michael Snyder
2009-08-23 18:32 ` Eli Zaretskii
2009-08-23 23:53 ` Hui Zhu
2009-08-23 23:56 ` Daniel Jacobowitz
2009-08-24 0:01 ` Hui Zhu
2009-08-24 7:46 ` Eli Zaretskii
2009-08-24 3:15 ` Hui Zhu
2009-08-24 19:20 ` Eli Zaretskii
2009-08-25 5:04 ` Hui Zhu
2009-08-25 18:45 ` Eli Zaretskii
2009-08-26 3:19 ` Hui Zhu
2009-08-26 3:27 ` Eli Zaretskii
2009-08-26 7:20 ` Hui Zhu
2009-08-26 17:37 ` Eli Zaretskii
2009-08-27 0:05 ` Michael Snyder
2009-08-27 0:32 ` Michael Snyder
2009-08-27 1:50 ` Hui Zhu
2009-08-27 15:35 ` Hui Zhu
2009-08-28 1:44 ` Michael Snyder
2009-08-28 2:14 ` Hui Zhu
2009-08-28 6:16 ` Michael Snyder
2009-08-28 8:46 ` Hui Zhu
2009-08-30 1:12 ` Michael Snyder
2009-08-27 1:44 ` Hui Zhu
2009-08-29 6:51 ` Hui Zhu
2009-08-24 20:31 ` Eli Zaretskii
2009-08-25 6:53 ` Hui Zhu
2009-08-23 18:24 ` Eli Zaretskii
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