[bug-libsigsegv] Re: sigsegv on s390 only giving start address of page in segv handler

[Christoph Egger]

Hi all!

Bruno Haible <address@hidden> writes:
>>     libsigsegv doesn't cope well with s390 at the moment. This is caused
>> by the fact, that linux masks the address for sigsegv:
>> 
>>   mm/fault.c:#define __FAIL_ADDR_MASK 0x7ffff000
>> 
>> So the last 12 bit of information are lost.
>
> Thanks for the analysis. Indeed at least the 'sigsegv1' test will fail in this
> situation.
>
> Have you reported the problem to the linux-kernel mailing list, or to the
> maintainers of the s390 part of Linux?
>
>> Forcing libsigsegv to use 
>> POSIX signal handlers othewise makes a library that passes all the tests
>> apart from the exact fault location.
>
> That sounds promising, if the kernel problem was fixed.

    It seems the FAIL_ADDR_MASK is some handling for hardware
limitation? Is there some chance to get near a exact address for
segfault handlers or will we have to just live with the absence of this
facility on application level?

Regards

    Christoph

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A. Because it breaks the logical sequence of discussion
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