Re: vdso handling

Alan Modra
2014-03-13T13:03:33Z

On Thu, Mar 13, 2014 at 10:52:16AM +0100, Mark Wielaard wrote:
> On Thu, 2014-03-13 at 11:31 +1030, Alan Modra wrote:
> > It wouldn't
> > help in the vdso case anyway, since the problem there is that you only
> > have the loaded part of the original ELF file.
>
> Note that the vdso is often special, compared to other ELF dsos, because
> the loaded part is just the complete ELF image in memory. Since they are
> very simple they will just have one PT_LOAD at offset zero and if the
> image is smaller than the page size then the whole file is just simply
> mapped into memory completely. So by fetching the vdso ELF image from
> remote memory you should be able to get the section headers and the
> not-allocated sections too.

Yes, but if the vdso does not fit in a page (which incidentally is
inferred by program header p_align), then you may lose the section
headers. I was assuming this was the case.

--
Alan Modra
Australia Development Lab, IBM