[v2] powerpc/64: handle linker stubs in low .text code

[Michael Ellerman]

On Mon, 2017-05-29 at 07:39:40 UTC, Nicholas Piggin wrote:
> Very large kernels may require linker stubs for branches from HEAD
> text code. The linker may place these stubs before the HEAD text
> sections, which breaks the assumption that HEAD text is located at 0
> (or the .text section being located at 0x7000/0x8000 on Book3S
> kernels).
> 
> Provide an option to create a small section just before the .text
> section with an empty 256 - 4 bytes, and adjust the start of the .text
> section to match. The linker will tend to put stubs in that section
> and not break our relative-to-absolute offset assumptions.
> 
> This causes a small waste of space on common kernels, but allows large
> kernels to build and boot. For now, it is an EXPERT config option,
> defaulting to =n, but a reference is provided for it in the build-time
> check for such breakage. This is good enough for allyesconfig and
> custom users / hackers.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/951eedebcdea06fdcc742c82dc3475

cheers