[PATCH Dovetail v2 3/6] arm: irq_pipeline: Fix fault_{entry,exit} bypass in hw_breakpoint_pending

HW breakpoint / watchpoint handling was bypassing the fault_{entry,exit}
machinery. As a result it could happen that the inband IRQ mask was
touched from the OOB stage.

There is one more problem in the HW bp/wp handling related to
interrupts_enabled(). This one will be fixed in a separate patch.

Signed-off-by: Florian Bezdeka <[email protected]>
---
 arch/arm/include/asm/dovetail.h         | 1 +
 arch/arm/include/asm/trace/exceptions.h | 3 ++-
 arch/arm/kernel/hw_breakpoint.c         | 6 ++++++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/dovetail.h b/arch/arm/include/asm/dovetail.h
index 795a1fb903ec29f4c2fb7b25e70980796804acc0..eeb5d16ad032044a2587822f6b35074d664a9bbc 100644
--- a/arch/arm/include/asm/dovetail.h
+++ b/arch/arm/include/asm/dovetail.h
@@ -16,6 +16,7 @@
 #define ARM_TRAP_VFP		6	/* VFP floating point exception */
 #define ARM_TRAP_UNDEFINSTR	7	/* Undefined instruction */
 #define ARM_TRAP_ALIGNMENT	8	/* Unaligned access exception */
+#define ARM_TRAP_HW_BREAK	9	/* HW break or watchpoint exception */
 
 #if !defined(__ASSEMBLY__)
 
diff --git a/arch/arm/include/asm/trace/exceptions.h b/arch/arm/include/asm/trace/exceptions.h
index bdb666b3da4e364e0d7e33337be3e8ad8aeedb88..f0164e55efc31a4f363764d2c5c84761f3ea34d4 100644
--- a/arch/arm/include/asm/trace/exceptions.h
+++ b/arch/arm/include/asm/trace/exceptions.h
@@ -21,7 +21,8 @@
 			__trace_trap(ARM_TRAP_FPU),		\
 			__trace_trap(ARM_TRAP_VFP),		\
 			__trace_trap(ARM_TRAP_UNDEFINSTR),	\
-			__trace_trap(ARM_TRAP_ALIGNMENT))
+			__trace_trap(ARM_TRAP_ALIGNMENT),	\
+			__trace_trap(ARM_TRAP_HW_BREAK))
 
 DECLARE_EVENT_CLASS(ARM_trap_event,
 	TP_PROTO(int trapnr, struct pt_regs *regs),
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index cd4b34c96e35e9e63e9a1ade1aeb415c22d32b00..d4b7953eff35d4c0194dec9aed7f7b17af5cf1f4 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -26,6 +26,7 @@
 #include <asm/current.h>
 #include <asm/hw_breakpoint.h>
 #include <asm/traps.h>
+#include <asm/trap_entry.h>
 
 /* Breakpoint currently in use for each BRP. */
 static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
@@ -942,9 +943,12 @@ static void hw_breakpoint_cfi_handler(struct pt_regs *regs)
 static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
 				 struct pt_regs *regs)
 {
+	unsigned long irqflags;
 	int ret = 0;
 	u32 dscr;
 
+	irqflags = fault_entry(ARM_TRAP_HW_BREAK, regs);
+
 	preempt_disable();
 
 	if (interrupts_enabled(regs))
@@ -973,6 +977,8 @@ static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
 
 	preempt_enable();
 
+	fault_exit(ARM_TRAP_HW_BREAK, regs, irqflags);
+
 	return ret;
 }
 

-- 
2.54.0