[Crash-utility] Additional fix for per-cpu data symbol naming problem

[Ryota Ozaki]

Hi Dave

Thanks for quick response.

On Wed, May 19, 2010 at 9:54 PM, Dave Anderson <anderson at redhat.com> wrote:
>
> ----- "Ryota Ozaki" <ozaki.ryota at gmail.com> wrote:
>
>> Hi,
>>
>> I tried crash 5.0.3 for linux 2.6.34 (x86_64) and faced the problem
>> about per-cpu data symbol naming, which is described in ChangeLog
>> as it's already fixed. I observed to fix the problem and found the
>> following fix for x86_64_verify_symbol() in x86_64.c helped me.
>>
>> I'm not sure whether the fix is correct or not, but it would be help for
>> correct fix.
>>
>> Thanks,
>>   ozaki-r
>>
>>
>> --- x86_64.c.orig       2010-05-19 12:26:11.000000000 +0000
>> +++ x86_64.c    2010-05-19 08:23:30.000000000 +0000
>> @@ -1974,7 +1974,7 @@
>>                         if (STRNEQ(name, "per_cpu") ||
>>                             STREQ(name, "__per_cpu_end"))
>>                                 return TRUE;
>> -                       if (type == 'V')
>> +                       if (type == 'V' || type == 'D' || type == 'd')
>>                                 return TRUE;
>>                 }
>
> Yes, I already have that same patch queued for the next release,
> which I hope to have ready today or tomorrow.

Good news!

>
> The fix in 5.0.3 was based upon my own builds of 2.6.34 kernels
> that introduced the new per-cpu symbol naming scheme.  But when
> I build x86_64 kernels, the per-cpu symbol types are type 'V'.
>
> For example, here's a 2.6.34-rc5 kernel that I built -- note there
> are few absolute ('a' or 'A') symbols after "__per_cpu_start", but
> all the "real" per-cpu symbols are type 'V':
>
> # strings vmlinux | grep "Linux version"
> Linux version 2.6.34-rc5 (root at intel-d3c4702-01.rhts.eng.bos.redhat.com) (gcc version 4.4.3 20100121 (Red Hat 4.4.3-1) (GCC) ) #1 SMP Fri Apr 30 18:20:16 EDT 2010
> # nm -Bn vmlinux
>                 w __crc_softirq_work_list
>                 U do_hypervisor_callback
> 0000000000000000 a L3_PAGE_OFFSET
> 0000000000000000 A VDSO32_PRELINK
> 0000000000000000 D __per_cpu_start
> 0000000000000000 V irq_stack_union
> 0000000000000000 A xen_irq_disable_direct_reloc
> 0000000000000000 A xen_save_fl_direct_reloc
> 0000000000000040 A VDSO32_vsyscall_eh_frame_size
> 0000000000000100 a i
> 0000000000000100 a vector
> 0000000000000110 a L4_PAGE_OFFSET
> 00000000000001e7 A kexec_control_code_size
> 00000000000001f0 A VDSO32_NOTE_MASK
> 00000000000001fe a L3_START_KERNEL
> 00000000000001ff a L4_START_KERNEL
> 0000000000000400 A VDSO32_sigreturn
> 0000000000000410 A VDSO32_rt_sigreturn
> 0000000000000420 A VDSO32_vsyscall
> 0000000000000430 A VDSO32_SYSENTER_RETURN
> 0000000000004000 V gdt_page
> 0000000000005000 V exception_stacks
> 000000000000b000 V xen_vcpu
> 000000000000b020 V xen_vcpu_info
> 000000000000b060 V idt_desc
> 000000000000b070 V xen_cr0_value
> 000000000000b080 V xen_mc_irq_flags
> 000000000000b0a0 V mc_buffer
> 000000000000c5b0 V xen_cr3
> 000000000000c5b8 V xen_current_cr3
> ... [ cut ] ...
> 0000000000016700 V cpu_tlbstate
> 0000000000016740 V runqueues
> 0000000000017100 V sched_clock_data
> 0000000000017140 V cfd_data
> 0000000000017180 V call_single_queue
> 00000000000171c0 V csd_data
> 00000000000171e8 D __per_cpu_end
> ...
>
> Although I still don't understand why it happens (compiler?
> CONFIG option?), a patch to continue recognizing 'd' and 'D'
> symbols is obviously needed.

Here is my output. Hope it would be your help.

# strings vmlinux | grep "Linux version"
Linux version 2.6.34-20100517.core (root at host103) (gcc version 4.1.2
20070925 (Red Hat 4.1.2-33)) #1 SMP Tue May 18 16:14:49 JST 2010
# nm -Bn vmlinux |grep -A 10 __per_cpu_start
0000000000000000 D __per_cpu_start
0000000000000000 D irq_stack_union
0000000000000040 A VDSO32_vsyscall_eh_frame_size
0000000000000110 a L4_PAGE_OFFSET
00000000000001e7 A kexec_control_code_size
00000000000001fe a L3_START_KERNEL
00000000000001ff a L4_START_KERNEL
0000000000000400 A VDSO32_sigreturn
0000000000000410 A VDSO32_rt_sigreturn
0000000000000420 A VDSO32_vsyscall
0000000000000430 A VDSO32_SYSENTER_RETURN
# nm -Bn vmlinux |grep -B 10 __per_cpu_end
0000000000010da0 d ipv4_cookie_scratch
0000000000010f40 D init_tss
0000000000013200 D irq_stat
0000000000013240 D cpu_info
0000000000013300 D cpu_tlbstate
0000000000013340 d runqueues
0000000000013c80 d sched_clock_data
0000000000013cc0 d cfd_data
0000000000013d00 d call_single_queue
0000000000013d40 d csd_data
0000000000013d68 D __per_cpu_end

Thanks,
  ozaki-r


>
> Thanks,
>  Dave
>
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