[PATCH v5 04/22] powerpc/32: Reorder instructions to avoid using CTR in syscall entry
STALE2037d
LANDED
From: Christophe Leroy <hidden>
Date: 2021-02-08 16:27:46
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
Landed in mainline as 2c59e5104821 on 2021-02-11.
Now that we are using rfi instead of mtmsr to reactivate MMU, it is possible to reorder instructions and avoid the need to use CTR for stashing SRR0. null_syscall on 8xx is reduced by 3 cycles (283 => 280 cycles). Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/kernel/head_32.h | 22 ++++++++++------------ 1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 4029c51dce5d..24dc326e0d56 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h@@ -116,30 +116,28 @@ .endm .macro SYSCALL_ENTRY trapno - mfspr r12,SPRN_SPRG_THREAD mfspr r9, SPRN_SRR1 - mfspr r11, SPRN_SRR0 - mtctr r11 + mfspr r10, SPRN_SRR0 andi. r11, r9, MSR_PR + beq- 99f + LOAD_REG_IMMEDIATE(r11, MSR_KERNEL) /* can take exceptions */ + lis r12, 1f@h + ori r12, r12, 1f@l + mtspr SPRN_SRR1, r11 + mtspr SPRN_SRR0, r12 + mfspr r12,SPRN_SPRG_THREAD mr r11, r1 lwz r1,TASK_STACK-THREAD(r12) - beq- 99f + tovirt(r12, r12) addi r1, r1, THREAD_SIZE - INT_FRAME_SIZE - LOAD_REG_IMMEDIATE(r10, MSR_KERNEL) /* can take exceptions */ - mtspr SPRN_SRR1, r10 - lis r10, 1f@h - ori r10, r10, 1f@l - mtspr SPRN_SRR0, r10 rfi 1: - tovirt(r12, r12) stw r11,GPR1(r1) stw r11,0(r1) mr r11, r1 + stw r10,_NIP(r11) mflr r10 stw r10, _LINK(r11) - mfctr r10 - stw r10,_NIP(r11) mfcr r10 rlwinm r10,r10,0,4,2 /* Clear SO bit in CR */ stw r10,_CCR(r11) /* save registers */
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2.25.0