[Valgrind-developers] ELF question

[Julian S. <js...@ac...>]

V is declining to read debug info from various .so's on various 
PPC distros.  It complains, when reading the section headers, that
one of the sections it's looking for (.plt, in this example)
has an offset+size value which extends beyond the end of the file.
And it's correct to do so:

sewardj@minnie:~$ readelf -S /usr/lib/qt-3.3/plugins/styles/wonderland.so

There are 28 section headers, starting at offset 0x156e4:

Section Headers:
[Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
[...]
[24] .plt              NOBITS          00025618 0155f0 000918 00 WAX  0   0  4

Offset(0x0155f0) + Size(0x000918) = 0x15f08 = 89864, whilst the file
size is only 88900.

Also it's a bit strange that there are a four of sections that start
at the same offset:

[23] .sbss             NOBITS          000255f0 0155f0 000028 00  WA  0   0  8
[24] .plt              NOBITS          00025618 0155f0 000918 00 WAX  0   0  4
[25] .bss              NOBITS          00025f30 0155f0 000000 00  WA  0   0  1
[26] .gnu_debuglink    PROGBITS        00000000 0155f0 000018 00      0   0  4

Any ideas?

This only happens for 1-in-10-ish .so's (very approximately).
For the rest the debuginfo reader works fine.  At first I thought
it might be an endianness thing, but the fact that V's numbers agree
with readelf's dissuaded me of that.

J