[gold patch] PR 17643: Add -z bndplt support (for Intel MPX)

H.J. Lu hjl.tools@gmail.com
Tue Jan 10 22:03:00 GMT 2017


On Thu, Dec 15, 2016 at 5:20 PM, Cary Coutant <ccoutant@gmail.com> wrote:
> HJ,
>
> Here's a preliminary patch to add -z bndplt support to gold. If you
> could take a look and give it a try, I'd appreciate it. I'm hoping to
> get this into the 2.28 release.
>
> I haven't added any tests yet, and I haven't yet adjusted the EH table
> descriptors for the new PLT entries. Do you have a spec or a template
> for what the EH descriptors should look like?

I just noticed that ld generates incorrect unwind info for BND PLT.

> The PLT code seems to match what ld generates (which does not quite
> match the psABI spec -- see my email on the psABI list), and a basic
> test program works. I haven't actually run any tests that verify that
> the BND registers aren't getting cleared, though.
>
> Gold adds the APLT into the .plt section rather than creating a new
> .plt.bnd section, and that seems to be preventing objdump and gdb from
> correctly symbolizing some of the code, but I'd hope those can be
> fixed so that they don't depend on having two (or three) separate .plt
> sections in the executable.
>

Ld is similar.  The difference is there is an entry in section table for
the second PLT.  There is no difference in memory layout.

-- 
H.J.



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