[Bug gold/15200] Runtime undefined reference to __exidx_start/_end

[petechou at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15200

--- Comment #3 from pete <petechou at gmail dot com> 2013-03-07 02:39:59 UTC ---
Hello,

Let me describe this issue again. The runtime undefined reference is because:

1. Using ld.gold to link against libraries (say libc.so) in android ndk-r8, and
those libraries are probably generated by ld.bfd.

$ readelf -s /tmp/android-ndk-r8/platforms/android-14/arch-arm/usr/lib/libc.so
| grep exidx
   106: 0000cf44     0 NOTYPE  GLOBAL DEFAULT  ABS __exidx_end
   334: 0000cf44     0 NOTYPE  GLOBAL DEFAULT  ABS __exidx_start
   730: 000089a8    20 FUNC    GLOBAL DEFAULT    4 __gnu_Unwind_Find_exidx
   118: 0000cf44     0 NOTYPE  GLOBAL DEFAULT  ABS __exidx_end
   346: 0000cf44     0 NOTYPE  GLOBAL DEFAULT  ABS __exidx_start
   742: 000089a8    20 FUNC    GLOBAL DEFAULT    4 __gnu_Unwind_Find_exidx

2. Running the library on a newer version (say 4.2) of Android system, and
there are no __exidx_start/_end symbols in the libraries, e.g, libc.so.

$ readelf -s $AOSP/out/target/product/generic/system/lib/libc.so | grep exidx
   882: 0000e929     4 FUNC    GLOBAL DEFAULT    7 __gnu_Unwind_Find_exidx
   891: 00000000     0 FUNC    GLOBAL DEFAULT  UND dl_unwind_find_exidx

So, it's fine to generate dynamic relocations for undefined symbols, but I
think section/segment symbols in output probably should be defined locally
anyway, if we're going to define them. Using section/segment definition in
DT_NEEDED doesn't seem to be the correct behavior?

BTW, I also checked ld.bfd also defines __exidx_start/_end locally.

$ arm-linux-androideabi-ld.bfd -shared -o libplasma.so plasma.o libc.so 
$ readelf -s libplasma.so | grep exidx
     3: 00003980     0 NOTYPE  LOCAL  DEFAULT  ABS __exidx_end
     4: 00003858     0 NOTYPE  LOCAL  DEFAULT  ABS __exidx_start
    64: 00000000     0 FUNC    WEAK   DEFAULT  UND __gnu_Unwind_Find_exidx
   119: 00003980     0 NOTYPE  LOCAL  DEFAULT  ABS __exidx_end
   121: 00003858     0 NOTYPE  LOCAL  DEFAULT  ABS __exidx_start
   185: 00000000     0 FUNC    WEAK   DEFAULT  UND __gnu_Unwind_Find_exidx

Any comment about the issue and the patch?

-
Thanks,
Pete

-- 
Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.