Lassi Tuura <lat@xxxxxxx> writes: > I maintain a profiling utility which uses libunwind to capture stack > traces on x86-64. One of the several problems we ran into is that > stack tracing stops at global constructors for dynamically loaded > shared libraries. This seems to be because there is no unwind > information for _init / __do_global_ctors_aux. > > Is there any way to coax GCC to generate .eh_frame information for > these functions? You could try modifying the gcc Makefile to add -funwind-tables or -fasynchronous-unwind-tables to CRTSTUFF_CFLAGS. > I tried recompiling one library with and without > -fasynchronous-unwind-tables on a RHEL5-derived system with GCC > 4.3.4 + binutils 2.19.1, but didn't get the extra unwind info. In > fact -fasynchronous-unwind-tables didn't make any difference that I > could tell. -fasynchronous-unwind-tables should make a difference, and it is required if you want to be able to reliably unwind the stack from a signal handler. By the way, if you aren't using mainline gcc I think you'll find that the unwind information is incorrect in function epilogues, which means that unwinding the stack from a signal handler will break if the signal comes in as a function is returning. I think this may be fixed in mainline. Ian
