On Thu, 11 Jul 2019 12:24:03 +1000, Nicholas Piggin wrote:

This implements the tricky tracing and soft irq handling bits in C,
leaving the low level bit to asm.

A functional difference is that this redirects the interrupt exit to
a return stub to execute blr, rather than the lr address itself. This
is probably barely measurable on real hardware, but it keeps the link
stack balanced.

[...]

Patch 2 applied to powerpc/next.

[2/2] powerpc/64s: Remove idle workaround code from restore_cpu_cpufeatures
      https://git.kernel.org/powerpc/c/02b02ee1b05ef225525835b2d45faf31b3420bdd

cheers