Re: [Libunwind-devel] unw_get_proc_info is not signal-safe with debug-frames enabled

[Doug Moore]

Sergey,

The two patches together seem have to solved the problems of my test  
case, which I've run 14 times now without a problem.  I hope your  
changes find their way into libunwind soon.

Thanks for the help.

Doug Moore
Rice University

Quoting Sergey Korolev <address@hidden>:

> Doug,
>
> please try this patch also.
>
> пт, 7 сент. 2018 г. в 11:18, Doug Moore <address@hidden>:
>
> > Sergey,
> >
> > Your patch does remove memory allocation from the file, but oddly, I
> > still have problems with malloc being invoked.  The second time I
> > tested with your patch, I got hung here:
> >
> > #0  0x0000ffffb5a85d74 in __lll_lock_wait_private () from /lib64/libc.so.6
> > #1  0x0000ffffb5a0ea38 in malloc () from /lib64/libc.so.6
> > #2  0x0000ffffb59c15bc in qsort_r () from /lib64/libc.so.6
> > #3  0x0000ffffb592c8b0 in _ULaarch64_dwarf_find_debug_frame (found=0,
> > address@hidden, address@hidden,
> >      address@hidden, obj_name=0xffffb67dc440
> > "/home/dougm/.local/lib/hpctoolkit/ext-libs/libdwarf.so.1",
> > start=<optimized out>,
> >      end=<optimized out>) at dwarf/Gfind_proc_info-lsb.c:380
> > #4  0x0000ffffb592cab0 in _ULaarch64_dwarf_callback
> > (info=0xffffeb099ef8, size=<optimized out>, ptr=0xffffeb09a018) at
> > dwarf/Gfind_proc_info-lsb.c:667
> > #5  0x0000ffffb5abac88 in dl_iterate_phdr () from /lib64/libc.so.6
> > #6  0x0000ffffb592cff4 in _ULaarch64_dwarf_find_proc_info
> > (as=0xffffb5948230 <local_addr_space>, address@hidden,
> > address@hidden,
> >      need_unwind_info=1, arg=0xffffeb09a9a0) at
> > dwarf/Gfind_proc_info-lsb.c:693
> > #7  0x0000ffffb592a158 in fetch_proc_info (address@hidden,
> > ip=281473734119984) at dwarf/Gparser.c:454
> > #8  0x0000ffffb592ba08 in _ULaarch64_dwarf_reg_states_iterate
> > (c=0xffffeb09a1d0, cb=0xffffb6750844 <dwarf_reg_states_callback>,
> > token=0xffffeb09a1b8)
> >      at dwarf/Gparser.c:1034
> >
> > So, perhaps qsort isn't safe either, as odd as that seems.
> >
> > Doug
> >
> > Quoting Sergey Korolev <address@hidden>:
> >
> > > Doug,
> > >
> > > Can you try this patch?
> > >
> > http://lists.nongnu.org/archive/html/libunwind-devel/2018-06/msg00005.html
> > >
> > > пт, 7 сент. 2018 г. в 1:56, Doug Moore <address@hidden>:
> > >
> > >> It seems that unw_get_proc_info calls dwarf_make_proc_info, calls
> > >> fetch_proc_info, calls dwarf_find_proc_info, calls dl_iterate_phdr,
> > >> calls dwarf_callback, calls dwarf_find_debug_frame, calls calloc, and
> > >> callloc is not signal safe on the aarch64 device I'm testing on.
> > >>
> > >> So would there be a problem with replacing the calloc/realloc memory
> > >> management of 'tab' in Gfind_proc_info-lsb.c with mmap and munmap and
> > >> memcpy?
> > >>
> > >> Is the memory allocated for 'tab' freed anywhere?  It's not obvious that
> > >> it is.
> > >>
> > >> Thanks,
> > >>
> > >> Doug Moore
> > >>
> > >> Rice University
> > >>
> > >>
> > >> _______________________________________________
> > >> Libunwind-devel mailing list
> > >> address@hidden
> > >> https://lists.nongnu.org/mailman/listinfo/libunwind-devel
> > >>