Commit 63d60d0c authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64s/exception: avoid SPR RAW scoreboard stall in real mode entry 



Move SPR reads ahead of writes. Real mode entry that is not a KVM
guest is rare these days, but bad practice propagates.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent b0b2a93d

arch/powerpc/kernel/exceptions-64s.S

+7 −7
Original line number Diff line number Diff line
@@ -183,19 +183,19 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) 
	.endif

	.if \hsrr

	mfspr	r11,SPRN_HSRR0		/* save HSRR0 */

	mfspr	r12,SPRN_HSRR1		/* and HSRR1 */

	mtspr	SPRN_HSRR1,r10

	.else

	mfspr	r11,SPRN_SRR0		/* save SRR0 */

	mfspr	r12,SPRN_SRR1		/* and SRR1 */

	mtspr	SPRN_SRR1,r10

	.endif

	LOAD_HANDLER(r12, \label\())

	LOAD_HANDLER(r10, \label\())

	.if \hsrr

	mtspr	SPRN_HSRR0,r12

	mfspr	r12,SPRN_HSRR1		/* and HSRR1 */

	mtspr	SPRN_HSRR1,r10

	mtspr	SPRN_HSRR0,r10

	HRFI_TO_KERNEL

	.else

	mtspr	SPRN_SRR0,r12

	mfspr	r12,SPRN_SRR1		/* and SRR1 */

	mtspr	SPRN_SRR1,r10

	mtspr	SPRN_SRR0,r10

	RFI_TO_KERNEL

	.endif

	b	.	/* prevent speculative execution */