[PATCH] S390: Remove backchain-based fallback and use generic backtrace.c.

[Stefan Liebler]

On 3/4/20 4:24 PM, Florian Weimer wrote:
> * Stefan Liebler:
> 
>> After recent discussions:
>> - "[PATCH] s390: Remove backchain-based fallback from backtrace"
>>    https://www.sourceware.org/ml/libc-alpha/2020-02/msg00287.html
>>
>> - "Re: [PATCH 07/11] s390: Implement backtrace on top of <unwind-link.h>"
>>    https://www.sourceware.org/ml/libc-alpha/2020-02/msg00637.html
>>
>> We've checked and decided to remove the backchain:
>> We don't know of any environments without libgcc. Thus the backchain
>> unwinder is not used. If somebody builds with -mbackchain and without
>> fasynchronous-unwind-tables and has libgcc installed, then the
>> libgcc unwinder is called but not the backchain-based fallback.
>>
>> This step allows to get rid of the s390x specific backtrace.c files at all.
>> Furthermore the now used debug/backtrace.c version has some more
>> advantages:
>> - Free all resources if necessary. (libc_freeres_fn)
>> - Remove NULL address above _start.
>> - Check whether we make any progress while getting addresses.
> 
> Looks good to me.  Thanks for doing this.
> 
> Florian
> 

Committed.

Thanks,
Stefan