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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] fix the bug of gdb which debugs xen.
Sorry, my test build worked because I didn't set crash_debug=y. I'll test a
fix.
-- Keir
On 13/08/2009 03:54, "Caz Yokoyama" <cazyokoyama@xxxxxxxxx> wrote:
> Hello Keir,
> You code does not work. When each byte string is more than 0x7f, sign bit is
> extended and produce wrong value.
>
> diff -r 8a9f81672c76 xen/common/gdbstub.c
> --- a/xen/common/gdbstub.c Wed Aug 12 14:27:52 2009 +0100
> +++ b/xen/common/gdbstub.c Wed Aug 12 19:49:12 2009 -0700
> @@ -93,7 +93,7 @@
> return -1;
> }
>
> -char
> +unsigned char
> str2hex(const char *str)
> {
> return (char2hex(str[0]) << 4) | char2hex(str[1]);
> @@ -127,7 +127,7 @@
> x <<= 8;
> x += str2hex(*str);
> #elif defined(__LITTLE_ENDIAN)
> - x += (unsigned long)str2hex(*str) << (i*8);
> + x += (unsigned long)str2hex(str) << (i*8);
> #else
> # error unknown endian
> #endif
> diff -r 8a9f81672c76 xen/include/xen/gdbstub.h
> --- a/xen/include/xen/gdbstub.h Wed Aug 12 14:27:52 2009 +0100
> +++ b/xen/include/xen/gdbstub.h Wed Aug 12 19:49:12 2009 -0700
> @@ -29,7 +29,7 @@
> /* value <-> char (de)serialzers for arch specific gdb backends */
> char hex2char(unsigned long x);
> int char2hex(unsigned char c);
> -char str2hex(const char *str);
> +unsigned char str2hex(const char *str);
> unsigned long str2ulong(const char *str, unsigned long bytes);
>
> struct gdb_context {
> -caz
>
> -----Original Message-----
> From: Caz Yokoyama [mailto:caz@xxxxxxxxxxx]
> Sent: Wednesday, August 12, 2009 2:03 PM
> To: 'Keir Fraser'; 'xen-devel@xxxxxxxxxxxxxxxxxxx'
> Subject: RE: [Xen-devel] [PATCH] fix the bug of gdb which debugs xen.
>
> Probably, you mean.
>
> diff -r 8a9f81672c76 xen/common/gdbstub.c
> --- a/xen/common/gdbstub.c Wed Aug 12 14:27:52 2009 +0100
> +++ b/xen/common/gdbstub.c Wed Aug 12 14:00:20 2009 -0700
> @@ -127,7 +127,7 @@
> x <<= 8;
> x += str2hex(*str);
> #elif defined(__LITTLE_ENDIAN)
> - x += (unsigned long)str2hex(*str) << (i*8);
> + x += (unsigned long)str2hex(str) << (i*8);
> #else
> # error unknown endian
> #endif
> -caz
> -----Original Message-----
> From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
> Sent: Wednesday, August 12, 2009 6:30 AM
> To: Caz Yokoyama; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH] fix the bug of gdb which debugs xen.
>
> I rewrote it some more. Take a look at changeset 20054.
>
> -- Keir
>
> On 12/08/2009 13:52, "Caz Yokoyama" <cazyokoyama@xxxxxxxxx> wrote:
>
>> Hello Keir,
>> You are right and good points. Thank you. I did not aware them because
> only
>> environment I test is x86_64. How about this? I am glad if you check in. I
>> regularly update my local source code by "hg pull; hg up".
>> -caz
>>
>> -----Original Message-----
>> From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
>> Sent: Wednesday, August 12, 2009 12:58 AM
>> To: Caz Yokoyama; xen-devel@xxxxxxxxxxxxxxxxxxx
>> Subject: Re: [Xen-devel] [PATCH] fix the bug of gdb which debugs xen.
>>
>> I don't know whether you intend this for immediate checkin, but anyway:
>>
>> * Don't delete the sysenter logic in traps.c, leave it.
>> * I'm not sure about swap64() in gdbstub.c. The value may not be 64 bits
>> (e.g., running on i386), or the system may not be little endian. Might be
>> better to define an alternative to str2ulong() which is endian aware, like
>> gdb_write_to_packet_hex().
>>
>> -- Keir
>>
>> On 12/08/2009 03:15, "Caz Yokoyama" <cazyokoyama@xxxxxxxxx> wrote:
>>
>>> Hello,
>>> This patch fixes the bug of gdb which debugs Xen hypervisor, i.e. not
>> domU. As
>>> Emre Can Sezer reported in
>>> http://lists.xensource.com/archives/html/xen-devel/2009-01/msg00885.html,
>> once
>>> break point is hit, continue command produces SIGTRAP at
>> restore_all_xen().
>>> This patch makes continue command resume Xen running. I still see other
>> bugs
>>> like backtrace command does not show function name. But I hope this helps
>> your
>>> debug.
>>> FYI, related postings.
>>> http://lists.xensource.com/archives/html/xen-devel/2007-12/msg00678.html
>>>
>>
> http://www.filewatcher.com/p/xen_2.0.6.orig.tar.gz.2456215/xen-2.0/docs/misc
>> /X
>>> enDebugger-HOWTO.html
>>>
>>> connect gdb on step command
>>> --- a/xen/arch/x86/traps.c Thu Aug 06 13:27:53 2009 +0100
>>> +++ b/xen/arch/x86/traps.c Tue Aug 11 18:15:25 2009 -0700
>>> @@ -2977,13 +2977,7 @@
>>> if ( regs->eflags & EF_TF )
>>> {
>>> #ifdef __x86_64__
>>> - void sysenter_entry(void);
>>> - void sysenter_eflags_saved(void);
>>> - /* In SYSENTER entry path we can't zap TF until EFLAGS is
>> saved.
>>> */
>>> - if ( (regs->rip >= (unsigned long)sysenter_entry) &&
>>> - (regs->rip < (unsigned long)sysenter_eflags_saved) )
>>> - goto out;
>>> - WARN_ON(regs->rip != (unsigned long)sysenter_eflags_saved);
>>> + debugger_trap_fatal(TRAP_debug, regs);
>>> #else
>>> WARN_ON(1);
>>> #endif
>>>
>>> Value of gdb command is little endian.
>>> diff -r 13fe7f07df15 xen/common/gdbstub.c
>>> --- a/xen/common/gdbstub.c Thu Aug 06 13:27:53 2009 +0100
>>> +++ b/xen/common/gdbstub.c Tue Aug 11 18:15:25 2009 -0700
>>> @@ -53,6 +53,10 @@
>>>
>>> #define GDB_RETRY_MAX 10
>>>
>>> +#define swap16(_v) ((((u16)(_v)>>8)&0xff)|(((u16)(_v)&0xff)<<8))
>>> +#define swap32(_v)
>>> (((u32)swap16((u16)(_v))<<16)|(u32)swap16((u32)((_v)>>16)))
>>> +#define swap64(_v)
>>> (((u64)swap32((u32)(_v))<<32)|(u64)swap32((u32)((_v)>>32)))
>>> +
>>> struct gdb_cpu_info
>>> {
>>> atomic_t paused;
>>> @@ -489,6 +493,7 @@
>>> }
>>> ptr++;
>>> val = str2ulong(ptr, sizeof(unsigned long));
>>> + val = swap64(val);
>>> gdb_arch_write_reg(addr, val, regs, ctx);
>>> break;
>>> case 'D':
>>>
>>> Thank you.
>>> -Caz Yokoyama, caz at caztech dot com. 503-804-1028(m).
>>>
>>>
>>
>
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