Albert ARIBAUD albert@aribaud.net wrote on 2010/11/30 10:02:45:
Le 30/11/2010 09:47, Joakim Tjernlund a écrit :
Le 30/11/2010 08:06, Andreas Bießmann a écrit :
Signed-off-by: Andreas Bießmannandreas.devel@googlemail.com
- cmp r1, #0 /* symbol == NULL ? */
- beq fixnext
Nak. Don't hide a null pointer. NULL pointers are *not* relocated, since they are a constant. If a NULL ends up in relocation tables, that is because of a corruption *or* because it was to be relocated, and should thus never be ignored.
Depends, if the same routine is used for relocating fixups you need this test. Undefined weaks will generate a NULL fixup entry.
Understood.
note that I don't know how this routine is used so if just relocates the GOT you don't need to test for NULL.
Weren't there an effort to not use weak symbols any more?
ehh, not what I am aware of. Just that we should not use(ATM) undefined weaks.
If not, then a comment *must* be added to indicate that weak symbols can cause zero-filled reloc entries (I would suggest saying 'zero-filled' rather than 'NULL', because obviously readers will think of stdio's NULL).
zero-filled/NULL fixup entries. The GOT never holds NULL
We could possibly even send out a diagnostic message, but that'll be when the relocation code is turned to C language; I don't want to see asm code that calls printf.
No need really.