[PATCH v2 11/18] arm64: make mrs_s and msr_s macros work with LTO

[Sami Tolvanen]

On Thu, Nov 16, 2017 at 11:01:44AM -0600, Segher Boessenkool wrote:
> The thing with .purgem can work.  Inelegant, sure, but it can work :-)

It works, there are already functions in the kernel that use these
macros more than once. I agree that this might not be the most elegant
solution, but at least it allows us to use the same code path for both
compilers.

> Just make sure you do the macro define, the code that uses it, and the
> undefine, all in the same inline asm statement.

Yes, that's what we're doing here. Only KVM uses msr_s/msr_s directly,
everything else uses the (read|write)_sysreg_s wrappers instead, which
means the DEFINE/UNDEFINE macros are only needed in few places.

Sami