[PATCH 06/14] powerpc/64s: interrupt replay balance the return branch predictor

Nicholas Piggin npiggin at gmail.com
Mon Jun 12 09:58:27 AEST 2017


The __replay_interrupt code is branched to with bl, but the caller is
returned to directly with rfid from the interrupt.

Instead return to a return stub that returns to the caller with blr,
which should do better with the return predictor.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 arch/powerpc/kernel/exceptions-64s.S | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index a04ee0d7f88e..d55201625ea3 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1586,7 +1586,7 @@ _GLOBAL(__replay_interrupt)
 	 * we don't give a damn about, so we don't bother storing them.
 	 */
 	mfmsr	r12
-	mflr	r11
+	LOAD_REG_ADDR(r11, __replay_interrupt_return)
 	mfcr	r9
 	ori	r12,r12,MSR_EE
 	cmpwi	r3,0x900
@@ -1604,4 +1604,5 @@ FTR_SECTION_ELSE
 	cmpwi	r3,0xa00
 	beq	doorbell_super_common_msgclr
 ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
+__replay_interrupt_return:
 	blr
-- 
2.11.0



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