Re: [Libunwind-devel] Unwinding from optimzied shared library on linux

[Scott Biersdorff]

Hi Arun,

There are many more entries like this one in the library, here is another one:

00016430 0000000000000014 0000000000016434 FDE cie=00000000 
pc=00000000002aa500..00000000002aa5b1
   LOC           CFA      ra      
00000000002aa500 rsp+8    c-8   
00000000002aa504 rsp+48   c-8   
00000000002aa5b0 rsp+8    c-8  

This one might be of particular interest since the first location libunwind 
recovered (00000000002aa500), is in this address range.

Thanks,

- Scott


-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Arun Sharma
Sent: Saturday, September 20, 2014 1:05 AM
To: Scott Biersdorff
Cc: Lassi Tuura; address@hidden; Juul VanderSpek
Subject: Re: [Libunwind-devel] Unwinding from optimzied shared library on linux

On Tue, Sep 16, 2014 at 5:49 AM, Scott Biersdorff <address@hidden> wrote:

> Readelf does show an FDE entry but the information is very minimal:
>
>
>
> 000163c0 0000000000000014 00000000000163c4 FDE cie=00000000
> pc=0000000000253e00..0000000000253eb1
>
>    LOC           CFA      ra
>
> 0000000000253e00 rsp+8    c-8
>
> 0000000000253e04 rsp+48   c-8
>
> 0000000000253eb0 rsp+8    c-8
>

This is the problem that needs to be investigated. What this is showing is, 
only the addresses between 253e00..253eb1 have a chance of giving you a valid 
stack trace. I'm sure your shared library is much bigger than that.

Please compare to readelf -w /bin/ls on your system, which should show a lot 
more info.

Is something in your build process stripping out the information in .eh_frame 
ELF section from the library?

- Arun