linux-kernel - [PATCH v5 21/22] powerpc/32: Remove the counter in global

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Date:   Mon,  8 Feb 2021 15:10:41 +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>, npiggin@...il.com,
        msuchanek@...e.de
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v5 21/22] powerpc/32: Remove the counter in global_dbcr0

global_dbcr0 has two parts, 4 bytes to save/restore the
value of SPRN_DBCR0, and 4 bytes that are incremented/decremented
everytime something is saving/loading the above value.

This counter is only incremented/decremented, its value is never
used and never read.

Remove the counter and devide the size of global_dbcr0 by 2.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
v5: New
---
 arch/powerpc/kernel/entry_32.S   | 12 +++---------
 arch/powerpc/kernel/head_32.h    |  3 ---
 arch/powerpc/kernel/head_booke.h |  5 +----
 3 files changed, 4 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 7c824e8928d0..a574201b0eb6 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -175,14 +175,11 @@ transfer_to_handler:
 	addi	r11,r11,global_dbcr0@l
 #ifdef CONFIG_SMP
 	lwz	r9,TASK_CPU(r2)
-	slwi	r9,r9,3
+	slwi	r9,r9,2
 	add	r11,r11,r9
 #endif
 	lwz	r12,0(r11)
 	mtspr	SPRN_DBCR0,r12
-	lwz	r12,4(r11)
-	addi	r12,r12,-1
-	stw	r12,4(r11)
 #endif
 
 	b	3f
@@ -980,14 +977,11 @@ load_dbcr0:
 	addi	r11,r11,global_dbcr0@l
 #ifdef CONFIG_SMP
 	lwz	r9,TASK_CPU(r2)
-	slwi	r9,r9,3
+	slwi	r9,r9,2
 	add	r11,r11,r9
 #endif
 	stw	r10,0(r11)
 	mtspr	SPRN_DBCR0,r0
-	lwz	r10,4(r11)
-	addi	r10,r10,1
-	stw	r10,4(r11)
 	li	r11,-1
 	mtspr	SPRN_DBSR,r11	/* clear all pending debug events */
 	blr
@@ -996,7 +990,7 @@ load_dbcr0:
 	.align	4
 	.global global_dbcr0
 global_dbcr0:
-	.space	8*NR_CPUS
+	.space	4*NR_CPUS
 	.previous
 #endif /* !(CONFIG_4xx || CONFIG_BOOKE) */
 
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 282d8fd443a9..5001c6ecc3ec 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -166,9 +166,6 @@
 	addi	r11,r11,global_dbcr0@l
 	lwz	r12,0(r11)
 	mtspr	SPRN_DBCR0,r12
-	lwz	r12,4(r11)
-	addi	r12,r12,-1
-	stw	r12,4(r11)
 3:
 #endif
 	b	transfer_to_syscall		/* jump to handler */
diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index bfbd240cc8a2..5f565232b99d 100644
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -142,14 +142,11 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV)
 	addi	r11,r11,global_dbcr0@l
 #ifdef CONFIG_SMP
 	lwz	r10, TASK_CPU(r2)
-	slwi	r10, r10, 3
+	slwi	r10, r10, 2
 	add	r11, r11, r10
 #endif
 	lwz	r12,0(r11)
 	mtspr	SPRN_DBCR0,r12
-	lwz	r12,4(r11)
-	addi	r12,r12,-1
-	stw	r12,4(r11)
 
 3:
 	b	transfer_to_syscall	/* jump to handler */
-- 
2.25.0