Re: [PATCH][BZ #18508] S390: Fix "backtrace() returns infinitely deep stack frames with makecontext()".

[Stefan Liebler <stli at linux dot vnet dot ibm dot com>]

On 06/12/2015 05:40 PM, Andreas Schwab wrote:
> Stefan Liebler <stli@linux.vnet.ibm.com> writes:
>
> > Is there a way to load the correct libgcc_s.so on all architectures?
>
> #include <gnu/lib-names.h>
> dlopen(LIBGCC_S_SO, ...)
>
> Andreas.
Thanks.
Here is the patch with the enhanced tst-makecontext testcase.
It calls _Unwind_Backtrace within cf() function, which is called in a 
makecontext context and check if the callback function is not called 
infinitely times.

Tested on s390/s390x before and after this patch.
Before: Test fails; After: Test succeeds.

Ok to commit?

Bye Stefan

---
2015-06-15  Stefan Liebler  <stli@linux.vnet.ibm.com>

	[BZ #18508]
	* stdlib/Makefile ($(objpfx)tst-makecontext3):
	Depend on $(libdl).
	* stdlib/tst-makecontext.c (cf): Test if _Unwind_Backtrace
	is not called infinitely times.
	(backtrace_helper): New function.
	(trace_arg): New struct.
	(st1): Enlarge stack size.
	* sysdeps/unix/sysv/linux/s390/s390-32/__makecontext_ret.S:
	(__makecontext_ret): Omit cfi_startproc and cfi_endproc.
	* sysdeps/unix/sysv/linux/s390/s390-64/__makecontext_ret.S:
	Likewise.

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