[Bug other/24724] _Unwind_Backtrace() calls malloc

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24724

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
   Last reconfirmed|                            |2012-09-13
         Resolution|WONTFIX                     |
     Ever Confirmed|0                           |1

--- Comment #14 from H.J. Lu <hjl.tools at gmail dot com> 2012-09-13 13:43:42 UTC ---
(In reply to comment #13)
> There are two solutions to this:
> 
> (1) Make sure your binary provides PT_GNU_EH_FRAME.  This is the quickest
>     path through the unwinder, since the table is pre-sorted by the linker.

This isn't the problem.

> (2) Have your malloc detect the recursion and return NULL.  This will cause
>     the unwinder to perform a linear search through the unsorted tables.
>     It should not fail due to the fake out-of-memory condition, since it
>     was designed to handle throwing an exception during a true OOM condition.

The problem is _Unwind_Find_FDE in unwind-dw2-fde.c
calls search_object to find FDE in the registered objects,
which is loaded unsorted from .eh_frame section.  Can
we use .eh_frame_hdr section to load the sorted table
directly?