[LLVMbugs] [Bug 13650] New: llvm-objdump does not give information about all relocations

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=13650

             Bug #: 13650
           Summary: llvm-objdump does not give information about all
                    relocations
           Product: libraries
           Version: 3.1
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Archive library
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: Aleksandrs.Saveljevs at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


We are trying to use LLVM API to programmatically obtain a list of relocations
in an ELF file. The way we are doing this is exactly as llvm-objdump does it:
we are iterating through sections and in each section we are iterating over
relocations (see PrintRelocations() function at
https://llvm.org/svn/llvm-project/llvm/trunk/tools/llvm-objdump/llvm-objdump.cpp).
However, it does not give us relocation entries in .rela.dyn section.

Consider, for instance, the output of "readelf -r /bin/true":

$ readelf -r /bin/true

Relocation section '.rela.dyn' at offset 0xa80 contains 5 entries:
  Offset          Info           Type           Sym. Value    Sym. Name +
Addend
000000604c38  001800000006 R_X86_64_GLOB_DAT 0000000000000000 __gmon_start__ +
0
000000604de0  002800000005 R_X86_64_COPY     0000000000604de0 __progname + 0
000000604df0  002700000005 R_X86_64_COPY     0000000000604df0 stdout + 0
000000604e00  002a00000005 R_X86_64_COPY     0000000000604e00 __progname_full +
0
000000604e08  002c00000005 R_X86_64_COPY     0000000000604e08 stderr + 0

Relocation section '.rela.plt' at offset 0xaf8 contains 37 entries:
  Offset          Info           Type           Sym. Value    Sym. Name +
Addend
000000604c60  000100000007 R_X86_64_JUMP_SLO 0000000000000000 free + 0
000000604c68  000200000007 R_X86_64_JUMP_SLO 0000000000000000 abort + 0
000000604c70  000300000007 R_X86_64_JUMP_SLO 0000000000000000 __errno_location
+ 0
000000604c78  000400000007 R_X86_64_JUMP_SLO 0000000000000000 _exit + 0
000000604c80  000500000007 R_X86_64_JUMP_SLO 0000000000000000 __fpending + 0
...

(The list for .rela.plt has been truncated for brevity.)

If we now run "llvm-objdump-3.1 -r /bin/true", we will only get a list of
entries in .rela.plt section:

$ llvm-objdump-3.1 -r /bin/true | grep -c JUMP_SLOT
37

It would be nice if there would be a way to get at relocation entries in
.rela.dyn section.

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