From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH] powerpc/603: Avoid a pile of NOPs when not using SW LRU in TLB exceptions
Date: Fri, 7 May 2021 05:02:02 +0000 (UTC) [thread overview]
Message-ID: <603725297466959419628ef7964aaf3417fb647d.1620363691.git.christophe.leroy@csgroup.eu> (raw)
The SW LRU is in an MMU feature section. When not used, that's a
dozen of NOPs to fetch for nothing.
Define an ALT section that does the few remaining operations.
That also avoids a double read on SRR1 in the SW LRU case.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/head_book3s_32.S | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 065178f19a3d..f2a5ceff52b2 100644
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -518,8 +518,6 @@ BEGIN_FTR_SECTION
rlwinm r1,r1,0,~_PAGE_COHERENT /* clear M (coherence not required) */
END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
mtspr SPRN_RPA,r1
- mfspr r2,SPRN_SRR1 /* Need to restore CR0 */
- mtcrf 0x80,r2
BEGIN_MMU_FTR_SECTION
li r0,1
mfspr r1,SPRN_SPRG_603_LRU
@@ -531,9 +529,15 @@ BEGIN_MMU_FTR_SECTION
mfspr r2,SPRN_SRR1
rlwimi r2,r0,31-14,14,14
mtspr SPRN_SRR1,r2
-END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
+ mtcrf 0x80,r2
+ tlbld r3
+ rfi
+MMU_FTR_SECTION_ELSE
+ mfspr r2,SPRN_SRR1 /* Need to restore CR0 */
+ mtcrf 0x80,r2
tlbld r3
rfi
+ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
DataAddressInvalid:
mfspr r3,SPRN_SRR1
rlwinm r1,r3,9,6,6 /* Get load/store bit */
@@ -607,9 +611,15 @@ BEGIN_MMU_FTR_SECTION
mfspr r2,SPRN_SRR1
rlwimi r2,r0,31-14,14,14
mtspr SPRN_SRR1,r2
-END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
+ mtcrf 0x80,r2
+ tlbld r3
+ rfi
+MMU_FTR_SECTION_ELSE
+ mfspr r2,SPRN_SRR1 /* Need to restore CR0 */
+ mtcrf 0x80,r2
tlbld r3
rfi
+ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
#ifndef CONFIG_ALTIVEC
#define altivec_assist_exception unknown_exception
--
2.25.0
next reply other threads:[~2021-05-07 5:02 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-07 5:02 Christophe Leroy [this message]
2021-06-06 12:08 ` [PATCH] powerpc/603: Avoid a pile of NOPs when not using SW LRU in TLB exceptions Michael Ellerman
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