[PATCH 05/10] powerpc/603: Don't handle kernel page TLB misses when not need

From: Christophe Leroy
Date: Fri Jan 25 2019 - 07:34:17 EST


ITLB miss on kernel pages only occur with CONFIG_MODULES and
CONFIG_DEBUG_PAGEALLOC.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
arch/powerpc/kernel/head_32.S | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index 53f65124edd5..3bbf937ad634 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -500,15 +500,19 @@ InstructionTLBMiss:
*/
/* Get PTE (linux-style) and check access */
mfspr r3,SPRN_IMISS
+#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC)
lis r1,PAGE_OFFSET@h /* check if kernel address */
cmplw 0,r1,r3
+#endif
mfspr r2, SPRN_SPRG_603_PGDIR
li r1,_PAGE_USER|_PAGE_PRESENT|_PAGE_EXEC /* low addresses tested as user */
+#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC)
bge- 112f
mfspr r2,SPRN_SRR1 /* and MSR_PR bit from SRR1 */
rlwimi r1,r2,32-12,29,29 /* shift MSR_PR to _PAGE_USER posn */
lis r2, (swapper_pg_dir - PAGE_OFFSET)@ha /* if kernel address, use */
addi r2, r2, (swapper_pg_dir - PAGE_OFFSET)@l /* kernel page table */
+#endif
112: rlwimi r2,r3,12,20,29 /* insert top 10 bits of address */
lwz r2,0(r2) /* get pmd entry */
rlwinm. r2,r2,0,0,19 /* extract address of pte page */
--
2.13.3