Re: vDSO for ppc64 : Preliminary release #3

From: Jakub Jelinek
Date: Thu Sep 09 2004 - 04:18:33 EST


On Thu, Sep 09, 2004 at 06:43:03PM +1000, Benjamin Herrenschmidt wrote:
> - The current glibc code for dealing with vdso's is not completely
> appropriate for ppc64 in particular since we do need relocations to be
> performed on the OPD section (thanks mprotect + COW, it actually works)
> if the library is ever mapped at a differnet address than it's native
> 0x100000 (via the new phdr for example).
> The current glibc code forces l_relocated to 1 for all vdso's (which is
> fine for archs without need to relocate function descriptors).

That is on purpose, even if vDSO location is randomized (e.g. on IA-32),
no relocations should happen, so that the vDSO can be shared (unless
written into by the debugger, that is). ld.so knows how to deal with
.dynamic section relocation of vDSOs.

Jakub
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