linux-kernel - [PATCH] powerpc/32: Remove unneccessary calculations in load_up

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Date:   Wed, 18 Aug 2021 08:47:28 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/32: Remove unneccessary calculations in
 load_up_{fpu/altivec}

No need to re-read SPRN_THREAD, we can calculate thread address
from current (r2).

And remove a reload of value 1 into r4 as r4 is already 1.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/kernel/fpu.S    | 3 +--
 arch/powerpc/kernel/vector.S | 4 +---
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/fpu.S b/arch/powerpc/kernel/fpu.S
index 6010adcee16e..ba4afe3b5a9c 100644
--- a/arch/powerpc/kernel/fpu.S
+++ b/arch/powerpc/kernel/fpu.S
@@ -91,8 +91,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_VSX)
 	isync
 	/* enable use of FP after return */
 #ifdef CONFIG_PPC32
-	mfspr	r5,SPRN_SPRG_THREAD	/* current task's THREAD (phys) */
-	tovirt(r5, r5)
+	addi	r5,r2,THREAD
 	lwz	r4,THREAD_FPEXC_MODE(r5)
 	ori	r9,r9,MSR_FP		/* enable FP for current */
 	or	r9,r9,r4
diff --git a/arch/powerpc/kernel/vector.S b/arch/powerpc/kernel/vector.S
index fc120fac1910..ba03eedfdcd8 100644
--- a/arch/powerpc/kernel/vector.S
+++ b/arch/powerpc/kernel/vector.S
@@ -65,9 +65,8 @@ _GLOBAL(load_up_altivec)
 1:
 	/* enable use of VMX after return */
 #ifdef CONFIG_PPC32
-	mfspr	r5,SPRN_SPRG_THREAD		/* current task's THREAD (phys) */
+	addi	r5,r2,THREAD
 	oris	r9,r9,MSR_VEC@h
-	tovirt(r5, r5)
 #else
 	ld	r4,PACACURRENT(r13)
 	addi	r5,r4,THREAD		/* Get THREAD */
@@ -81,7 +80,6 @@ _GLOBAL(load_up_altivec)
 	li	r4,1
 	stb	r4,THREAD_LOAD_VEC(r5)
 	addi	r6,r5,THREAD_VRSTATE
-	li	r4,1
 	li	r10,VRSTATE_VSCR
 	stw	r4,THREAD_USED_VR(r5)
 	lvx	v0,r10,r6
-- 
2.25.0