linux-kernel - [PATCH v1 06/15] powerpc: Remove address and errorcode arguments from do

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Message-Id: <0246430576c2ff0aed1d35ccbd6f44e658908102.1608641533.git.christophe.leroy@csgroup.eu>
Date:   Tue, 22 Dec 2020 13:28:28 +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>, npiggin@...il.com
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v1 06/15] powerpc: Remove address and errorcode arguments from
 do_break()

Let do_break() retrieve address and errorcode from regs.

This simplifies the code and shouldn't impeed performance as
address and errorcode are likely still hot in the cache.

Suggested-by: Nicholas Piggin <npiggin@...il.com>
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/debug.h     | 3 +--
 arch/powerpc/kernel/exceptions-64s.S | 2 --
 arch/powerpc/kernel/head_8xx.S       | 5 -----
 arch/powerpc/kernel/process.c        | 8 +++-----
 4 files changed, 4 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/include/asm/debug.h b/arch/powerpc/include/asm/debug.h
index ec57daf87f40..0550eceab3ca 100644
--- a/arch/powerpc/include/asm/debug.h
+++ b/arch/powerpc/include/asm/debug.h
@@ -52,8 +52,7 @@ extern void do_send_trap(struct pt_regs *regs, unsigned long address,
 			 unsigned long error_code, int brkpt);
 #else
 
-extern void do_break(struct pt_regs *regs, unsigned long address,
-		     unsigned long error_code);
+void do_break(struct pt_regs *regs);
 #endif
 
 #endif /* _ASM_POWERPC_DEBUG_H */
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index cfbd1d690033..3ea067bcbb95 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -3262,8 +3262,6 @@ handle_page_fault:
 
 /* We have a data breakpoint exception - handle it */
 handle_dabr_fault:
-	ld      r4,_DAR(r1)
-	ld      r5,_DSISR(r1)
 	addi    r3,r1,STACK_FRAME_OVERHEAD
 	bl      do_break
 	/*
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 52702f3db6df..81f3c984f50c 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -364,11 +364,6 @@ do_databreakpoint:
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	mfspr	r4,SPRN_BAR
 	stw	r4,_DAR(r11)
-#ifdef CONFIG_VMAP_STACK
-	lwz	r5,_DSISR(r11)
-#else
-	mfspr	r5,SPRN_DSISR
-#endif
 	EXC_XFER_STD(0x1c00, do_break)
 
 	. = 0x1c00
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index a66f435dabbf..99c5e4fc5ff1 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -659,12 +659,10 @@ static void do_break_handler(struct pt_regs *regs)
 	}
 }
 
-void do_break (struct pt_regs *regs, unsigned long address,
-		    unsigned long error_code)
+void do_break(struct pt_regs *regs)
 {
 	current->thread.trap_nr = TRAP_HWBKPT;
-	if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
-			11, SIGSEGV) == NOTIFY_STOP)
+	if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, regs->dsisr, 11, SIGSEGV) == NOTIFY_STOP)
 		return;
 
 	if (debugger_break_match(regs))
@@ -681,7 +679,7 @@ void do_break (struct pt_regs *regs, unsigned long address,
 		do_break_handler(regs);
 
 	/* Deliver the signal to userspace */
-	force_sig_fault(SIGTRAP, TRAP_HWBKPT, (void __user *)address);
+	force_sig_fault(SIGTRAP, TRAP_HWBKPT, (void __user *)regs->dar);
 }
 #endif	/* CONFIG_PPC_ADV_DEBUG_REGS */
 
-- 
2.25.0