Re: [Libunwind-devel] libunwind backtrace on mips64

[Siddharth Bhojnagarwala]

Hi Arun,

Thanks for your help.   My .so did not have the unwind information for the ip 
in question here.  On investigation I found that the compiler was not 
generating this information for C code.  By using the compiler option 
-fexceptions, I was able to generate the unwind information for that code.  
That worked.

Regards,
Sid

-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Arun Sharma
Sent: Wednesday, December 21, 2011 8:52 PM
To: Siddharth Bhojnagarwala
Subject: Re: [Libunwind-devel] libunwind backtrace on mips64

On Wed, Dec 21, 2011 at 4:56 PM, Siddharth Bhojnagarwala <address@hidden> wrote:
>
>               >_ULmips_dwarf_search_unwind_table: ip=0x5555777023, 
> start_ip=0xfffffffffffcaad8
>  >_ULmips_dwarf_search_unwind_table: e->fde_offset = 18718, segbase = 
> 5579ca20, debug_frame_base = 0, fde_addr = 557b5138
>            >_ULmips_dwarf_extract_proc_info_from_fde: FDE @ 
> 0x55557b5138
>               >_ULmips_dwarf_extract_proc_info_from_fde: looking for 
> CIE at address 557b50e8
>               >parse_cie: CIE parsed OK, augmentation = "zRP", 
> handler=0x5555a3cb18
>               >_ULmips_dwarf_extract_proc_info_from_fde: FDE covers IP 
> 0x55557674f8-0x5555767590, LSDA=0x0
>                >put_rs_cache: unmasking signals/interrupts and 
> releasing lock
>               >_ULmips_dwarf_step: returning -10

Did you already try readelf -wf /your/lib.so to see if there is any unwind info 
for ip=0x5555777023? From the output above, the FDE covers only 
0x55557674f8-0x5555767590.

You might have to look into how the code at 0x5555777023 was built and see if 
you can coax the compiler to generate unwind info for all the IPs you might 
potentially want to unwind from.

 -Arun