[x86-64 psABI] RFC: Extend x86-64 PLT entry to support MPX

[Ian Lance Taylor]

On Tue, Jul 23, 2013 at 12:49 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>
> http://software.intel.com/sites/default/files/319433-015.pdf
>
> introduces 4 bound registers, which will be used for parameter passing
> in x86-64.  Bound registers are cleared by branch instructions.  Branch
> instructions with BND prefix will keep bound register contents.

I took a very quick look at the doc.  Why shouldn't we run the kernel
with BNDPRESERVE = 1, to avoid this behaviour of clearing the bound
registers on branch instructions?  That would let us avoid these
issues.


> I prefer the note section solution.  Any suggestions, comments?

I concur, but why not use the ELF attributes support rather than a new
note section?

Ian