Re: Help on build failure of patchelf on mips variants

James Cowgill <[email protected]> Tue, 05 Apr 2016 23:33:31 +0100

Newsgroups	gmane.linux.debian.ports.mips
Message-ID	<[email protected]>

Hi,

On Tue, 2016-04-05 at 16:13 -0300, Felipe Sateler wrote:
> I'm currently at a loss on why does patchelf fail to build (or rather,
> it fails its testsuite) on all mips variants[1].
> 
> Patchelf modifies ELF binaries, to add/remove RPATH and other
> sections. On all mips variants, some tests fail. From what I can tell,
> the loader complains that the new (altered) file has an invalid
> MIPS.abiflags section, and yet from what I can tell both the original
> and altered binaries have the same (as reported by readelf).
> 
> I have printed some more logs at the upstream issue tracker:
> https://github.com/NixOS/patchelf/issues/82
> 
> Any help would be appreciated. I'd rather not remove patchelf from mips.

I had a go at using patchelf on a hello world executable and the
executable immediately segfaulted. From 'readelf -e':

Before:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 3] .MIPS.abiflags    MIPS_ABIFLAGS   00400188 000188 000018 18   A  0   0  8

  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  ABIFLAGS       0x000188 0x00400188 0x00400188 0x00018 0x00018 R   0x8

After:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 1] .MIPS.abiflags    MIPS_ABIFLAGS   003fc174 000174 000018 18   A  0   0  4

  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  ABIFLAGS       0x004188 0x00400188 0x00400188 0x00018 0x00018 R   0x8

Here the ABIFLAGS segment (this is a special MIPS specific segment
type) is wrong after running patchelf. The offset and virtaddr are not
the same as the values used in the section header. Infact they don't
seem to point to any section at all. This is probably causing the
dynamic linker to read some garbage, causing the segfault.

If I recall, the ABIFLAGS were first read by glibc 2.22 which might be
why it only recently started failing.

James

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