GSoC'11: DWARF2 call frame information

[Xingxing Pan]

2011/3/22 Chagin Dmitry <dchagin at freebsd.org>:
> On Mon, Mar 21, 2011 at 05:36:13PM +0800, Xingxing Pan wrote:
>> 2011/3/21 Chagin Dmitry <dchagin at freebsd.org>:
>> >> powerfull script.
>> >>
>> >> Xingxing Pan
>> >
>> > hmm, which script? I think enough amd64, i386 and amd64/ia32.
>> >
>> > I suggest to write a example before continuing the conversation
>> > about the GSoC. For example (bcopy || bzero) && cpu_switch.
>> > Is it ok for you?
>> >
>> > --
>> > Have fun!
>> > chd
>> >
>>
>> Hi Chargin,
>>
>> Thank you for your reply.
>> The followings shows how I try to add DWARF for bcopy.
>>
>> --- ../8.2.0/sys/i386/include/asm.h     2011-03-21 14:35:56.111973722 +0800
>> +++ asm.h       2011-03-21 15:25:31.564636162 +0800
>> @@ -71,7 +71,7 @@
>>
>>  #define _ENTRY(x)      _START_ENTRY; \
>>                         .globl CNAME(x); .type CNAME(x), at function; CNAME(x):
>> -#define        END(x)          .size x, . - x
>> +#define        END(x)          .cfi_endproc; .size x, . - x
>>
>>  #ifdef PROF
>>  #define        ALTENTRY(x)     _ENTRY(x); \
>> @@ -80,9 +80,10 @@
>>                         popl %ebp; \
>>                         jmp 9f
>>  #define        ENTRY(x)        _ENTRY(x); \
>> -                       pushl %ebp; movl %esp,%ebp; \
>> +                       .cfi_startproc; \
>> +                       pushl %ebp; .cfi_adjust_cfa_offset 4; movl
>> %esp,%ebp; .cfi_def_cfa_register %ebp; \
>>                         call PIC_PLT(HIDENAME(mcount)); \
>> -                       popl %ebp; \
>> +                       popl %ebp; .cfi_def_cfa %esp, 4; \
>>
>> --- bcopy.S     2011-03-21 15:51:26.804203809 +0800
>> +++ ../8.2.0/lib/libc/i386/string/bcopy.S       2011-03-21
>> 14:28:15.023069890 +0800
>> @@ -51,9 +51,7 @@ ENTRY(bcopy)
>>  #endif
>>  #endif
>>         pushl   %esi
>> -       .cfi_adjust_cfa_offset 4;
>>         pushl   %edi
>> -       .cfi_adjust_cfa_offset 4;
>>  #if defined(MEMCOPY) || defined(MEMMOVE)
>>         movl    12(%esp),%edi
>>         movl    16(%esp),%esi
>> @@ -77,9 +75,7 @@ ENTRY(bcopy)
>>         rep
>>         movsb
>>         popl    %edi
>> -       .cfi_adjust_cfa_offset -4;
>>         popl    %esi
>> -       .cfi_adjust_cfa_offset -4;
>>         ret
>>  1:
>>         addl    %ecx,%edi       /* copy backwards. */
>> @@ -98,9 +94,7 @@ ENTRY(bcopy)
>>         rep
>>         movsl
>>         popl    %edi
>> -       .cfi_adjust_cfa_offset -4;
>>         popl    %esi
>> -       .cfi_adjust_cfa_offset -4;
>>         cld
>>         ret
>>  #ifdef MEMCOPY
>>
>> But I don't know how to add DWARF for cpu_switch, because I have no
>> idea about the circumstance when we need to backtrace through this
>> function. Suppose there's a cpu switch like this,
>> threadA->kernel->threadB. Then should the expected backtrace has the
>> following result?
>>
>> threadB's stack
>> kernel's stack
>> threadA's stack
>
>
> hmm, ok. good, avoid cpu_switch.
> First of all, please, read style(9) man page.
> In the second, evaluate the proposed plan (discussed with kib@):
>
> 1) Annotate libc, msun, rtld, libthr (you)
> 2) vdso (I'm)
> 3) Annotate signal trampolines (you, after vdso)
>
> And i'm going to understand what I need to do to start GSoC for you.
> Thanks!
>
>
> --
> Have fun!
> chd
>

I think the plan is ok for me.
Thank you.

Xingxing Pan