relocations against weak and global syms (for ARM)

[Harshad R Joglekar <harshad dot joglekar at wipro dot com>]

Hi,
I am not sure if it qualifies as a bug. Anyway here goes. I tried this
with the ARM assembler (binutils 2.11.2, target arm-elf). Note that
'foo' is a weak symbol, and that the relocation entries are not
consistent.

--------- input file ---------
.text
    b foo
    b foo + (end - start)
.weak foo
foo:
.equ start, 0
.equ end, 0

---------- output dump -----------------
readelf -r a.out

Relocation section '.rel.text' at offset 0x234 contains 2 entries:
  Offset    Info  Type            Symbol's Value  Symbol's Name
  00000000  00601 R_ARM_PC24            00000008  foo
  00000004  00101 R_ARM_PC24            00000000  .text
----------------------------------------

The first relocation is against 'foo' while the second is against
'.text'. So if the weak symbol 'foo' were to be overridden, the
relocation will remain unaffected. This seems to be happening because
tc_fix_adjustable() checks whether it's immediate argument is weak; it
doesn't recursively descend the expression tree.

Attempting a quick-fix, I tried a recusive algorithm, for a port I am
working on. But that leads to another problem :)
adjust_reloc_syms() rearranges a complex expression containing undefined
symbols / common symbols to a simple expression of the type "symbol
+ xxxx". But it does NOT do so for weak or global symbols. I tried
hacking symbols.c, but it didn't work for all kinds of expressions.
Is there a simpler / cleaner solution?

regards,
Harshad

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