linux-kernel - [PATCH] powerpc/8xx: fix single

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Date:	Thu, 18 Aug 2016 11:44:20 +0200 (CEST)
From:	Christophe Leroy <christophe.leroy@....fr>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Scott Wood <oss@...error.net>
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/8xx: fix single_step debug

SPRN_ICR must be read for clearing the internal freeze signal which
is asserted by the single step exception, otherwise the timebase and
decrementer remain freezed

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/include/asm/reg_8xx.h | 1 +
 arch/powerpc/kernel/traps.c        | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/arch/powerpc/include/asm/reg_8xx.h b/arch/powerpc/include/asm/reg_8xx.h
index feaf641..6dae71f 100644
--- a/arch/powerpc/include/asm/reg_8xx.h
+++ b/arch/powerpc/include/asm/reg_8xx.h
@@ -17,6 +17,7 @@
 #define SPRN_DC_DAT	570	/* Read-only data register */
 
 /* Misc Debug */
+#define SPRN_ICR	148
 #define SPRN_DPDR	630
 #define SPRN_MI_CAM	816
 #define SPRN_MI_RAM0	817
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 2cb5892..0f1f0ce 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -400,8 +400,16 @@ static inline int check_io_access(struct pt_regs *regs)
 #define REASON_TRAP		0x20000
 
 #define single_stepping(regs)	((regs)->msr & MSR_SE)
+#ifdef CONFIG_PPC_8xx
+static inline void clear_single_step(struct pt_regs *regs)
+{
+	regs->msr &= ~MSR_SE;
+	mfspr(SPRN_ICR);
+}
+#else
 #define clear_single_step(regs)	((regs)->msr &= ~MSR_SE)
 #endif
+#endif
 
 #if defined(CONFIG_4xx)
 int machine_check_4xx(struct pt_regs *regs)
-- 
2.1.0