linux-kernel - [RFC PATCH v1 10/41] powerpc/32: Handle bookE debugging in C in exception entry

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Message-Id: <bb5fc275f03ede032797b828dc2f6dc9e3e6dce5.1612864003.git.christophe.leroy@csgroup.eu>
Date:   Tue,  9 Feb 2021 09:56:34 +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
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [RFC PATCH v1 10/41] powerpc/32: Handle bookE debugging in C in
 exception entry

The handling of SPRN_DBCR0 and other registers can easily
be done in C instead of ASM.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/interrupt.h |  7 +++++++
 arch/powerpc/kernel/entry_32.S       | 23 -----------------------
 2 files changed, 7 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index e794111d7c03..d70c761edc00 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h
@@ -52,6 +52,13 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs, struct interrup
 	if (user_mode(regs))
 		account_cpu_user_entry();
 #endif
+
+#ifdef CONFIG_PPC_ADV_DEBUG_REGS
+	if (IS_ENABLED(CONFIG_PPC32) && unlikely(ts->debug.dbcr0 & DBCR0_IDM)) {
+		mtspr(SPRN_DBSR, -1);
+		mtspr(SPRN_DBCR0, global_dbcr0[smp_processor_id()]);
+	}
+#endif
 }
 
 /*
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 87c06e241fc2..971980d71b04 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -146,32 +146,9 @@ transfer_to_handler:
 	addi	r2, r12, -THREAD
 	addi	r11,r1,STACK_FRAME_OVERHEAD
 	stw	r11,PT_REGS(r12)
-#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
-	/* Check to see if the dbcr0 register is set up to debug.  Use the
-	   internal debug mode bit to do this. */
-	lwz	r12,THREAD_DBCR0(r12)
-	andis.	r12,r12,DBCR0_IDM@h
-#endif
 #ifdef CONFIG_PPC_BOOK3S_32
 	kuep_lock r11, r12
 #endif
-#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
-	beq+	3f
-	/* From user and task is ptraced - load up global dbcr0 */
-	li	r12,-1			/* clear all pending debug events */
-	mtspr	SPRN_DBSR,r12
-	lis	r11,global_dbcr0@ha
-	tophys_novmstack r11,r11
-	addi	r11,r11,global_dbcr0@l
-#ifdef CONFIG_SMP
-	lwz	r9,TASK_CPU(r2)
-	slwi	r9,r9,2
-	add	r11,r11,r9
-#endif
-	lwz	r12,0(r11)
-	mtspr	SPRN_DBCR0,r12
-#endif
-
 	b	3f
 
 2:	/* if from kernel, check interrupted DOZE/NAP mode and
-- 
2.25.0