[PATCH 13/14] powerpc/64: runlatch CTRL[RUN] set optimisation
From: Nicholas Piggin <npiggin@gmail.com>
Date: 2017-06-08 15:52:14
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
The CTRL register is read-only except bit 63 which is the run latch control. This means it can be updated with a mtspr rather than mfspr/mtspr. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/kernel/process.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 6273b5d5baec..29865c817b02 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c@@ -1991,12 +1991,8 @@ void show_stack(struct task_struct *tsk, unsigned long *stack) void notrace __ppc64_runlatch_on(void) { struct thread_info *ti = current_thread_info(); - unsigned long ctrl; - - ctrl = mfspr(SPRN_CTRLF); - ctrl |= CTRL_RUNLATCH; - mtspr(SPRN_CTRLT, ctrl); + mtspr(SPRN_CTRLT, CTRL_RUNLATCH); ti->local_flags |= _TLF_RUNLATCH; }
@@ -2004,13 +2000,9 @@ void notrace __ppc64_runlatch_on(void) void notrace __ppc64_runlatch_off(void) { struct thread_info *ti = current_thread_info(); - unsigned long ctrl; ti->local_flags &= ~_TLF_RUNLATCH; - - ctrl = mfspr(SPRN_CTRLF); - ctrl &= ~CTRL_RUNLATCH; - mtspr(SPRN_CTRLT, ctrl); + mtspr(SPRN_CTRLT, 0); } #endif /* CONFIG_PPC64 */
--
2.11.0