linux-kernel - [PATCH 4/5] Powerpc/hw-breakpoint: Optimize disable path

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Message-Id: <20190618042732.5582-5-ravi.bangoria@linux.ibm.com>
Date:   Tue, 18 Jun 2019 09:57:31 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     mpe@...erman.id.au
Cc:     benh@...nel.crashing.org, paulus@...ba.org, mikey@...ling.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        npiggin@...il.com, christophe.leroy@....fr,
        naveen.n.rao@...ux.vnet.ibm.com,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: [PATCH 4/5] Powerpc/hw-breakpoint: Optimize disable path

Directly setting dawr and dawrx with 0 should be enough to
disable watchpoint. No need to reset individual bits in
variable and then set in hw.

Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
---
 arch/powerpc/include/asm/hw_breakpoint.h |  3 ++-
 arch/powerpc/kernel/process.c            | 12 ++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index 78202d5fb13a..8acbbdd4a2d5 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -19,6 +19,7 @@ struct arch_hw_breakpoint {
 /* Note: Don't change the the first 6 bits below as they are in the same order
  * as the dabr and dabrx.
  */
+#define HW_BRK_TYPE_DISABLE		0x00
 #define HW_BRK_TYPE_READ		0x01
 #define HW_BRK_TYPE_WRITE		0x02
 #define HW_BRK_TYPE_TRANSLATE		0x04
@@ -68,7 +69,7 @@ static inline void hw_breakpoint_disable(void)
 	struct arch_hw_breakpoint brk;
 
 	brk.address = 0;
-	brk.type = 0;
+	brk.type = HW_BRK_TYPE_DISABLE;
 	brk.len = 0;
 	if (ppc_breakpoint_available())
 		__set_breakpoint(&brk);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f002d2ffff86..265fac9fb3a4 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -793,10 +793,22 @@ static inline int set_dabr(struct arch_hw_breakpoint *brk)
 	return __set_dabr(dabr, dabrx);
 }
 
+static int disable_dawr(void)
+{
+	if (ppc_md.set_dawr)
+		return ppc_md.set_dawr(0, 0);
+
+	mtspr(SPRN_DAWRX, 0);
+	return 0;
+}
+
 int set_dawr(struct arch_hw_breakpoint *brk)
 {
 	unsigned long dawr, dawrx, mrd;
 
+	if (brk->type == HW_BRK_TYPE_DISABLE)
+		return disable_dawr();
+
 	dawr = brk->address;
 
 	dawrx  = (brk->type & HW_BRK_TYPE_RDWR) << (63 - 58);
-- 
2.20.1