1 files changed, 117 insertions, 89 deletions

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index eeba38008032..b16c4568cb01 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -45,6 +45,7 @@ static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]);
 
 /* Number of BRP/WRP registers on this CPU. */
 static int core_num_brps;
+static int core_num_reserved_brps;
 static int core_num_wrps;
 
 /* Debug architecture version. */
@@ -53,87 +54,6 @@ static u8 debug_arch;
 /* Maximum supported watchpoint length. */
 static u8 max_watchpoint_len;
 
-/* Determine number of BRP registers available. */
-static int get_num_brps(void)
-{
-	u32 didr;
-	ARM_DBG_READ(c0, 0, didr);
-	return ((didr >> 24) & 0xf) + 1;
-}
-
-/* Determine number of WRP registers available. */
-static int get_num_wrps(void)
-{
-	/*
-	 * FIXME: When a watchpoint fires, the only way to work out which
-	 * watchpoint it was is by disassembling the faulting instruction
-	 * and working out the address of the memory access.
-	 *
-	 * Furthermore, we can only do this if the watchpoint was precise
-	 * since imprecise watchpoints prevent us from calculating register
-	 * based addresses.
-	 *
-	 * For the time being, we only report 1 watchpoint register so we
-	 * always know which watchpoint fired. In the future we can either
-	 * add a disassembler and address generation emulator, or we can
-	 * insert a check to see if the DFAR is set on watchpoint exception
-	 * entry [the ARM ARM states that the DFAR is UNKNOWN, but
-	 * experience shows that it is set on some implementations].
-	 */
-
-#if 0
-	u32 didr, wrps;
-	ARM_DBG_READ(c0, 0, didr);
-	return ((didr >> 28) & 0xf) + 1;
-#endif
-
-	return 1;
-}
-
-int hw_breakpoint_slots(int type)
-{
-	/*
-	 * We can be called early, so don't rely on
-	 * our static variables being initialised.
-	 */
-	switch (type) {
-	case TYPE_INST:
-		return get_num_brps();
-	case TYPE_DATA:
-		return get_num_wrps();
-	default:
-		pr_warning("unknown slot type: %d\n", type);
-		return 0;
-	}
-}
-
-/* Determine debug architecture. */
-static u8 get_debug_arch(void)
-{
-	u32 didr;
-
-	/* Do we implement the extended CPUID interface? */
-	if (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
-		pr_warning("CPUID feature registers not supported. "
-				"Assuming v6 debug is present.\n");
-		return ARM_DEBUG_ARCH_V6;
-	}
-
-	ARM_DBG_READ(c0, 0, didr);
-	return (didr >> 16) & 0xf;
-}
-
-/* Does this core support mismatch breakpoints? */
-static int core_has_mismatch_bps(void)
-{
-	return debug_arch >= ARM_DEBUG_ARCH_V7_ECP14 && core_num_brps > 1;
-}
-
-u8 arch_get_debug_arch(void)
-{
-	return debug_arch;
-}
-
 #define READ_WB_REG_CASE(OP2, M, VAL)		\
 	case ((OP2 << 4) + M):			\
 		ARM_DBG_READ(c ## M, OP2, VAL); \
@@ -211,6 +131,111 @@ static void write_wb_reg(int n, u32 val)
 	isb();
 }
 
+/* Determine debug architecture. */
+static u8 get_debug_arch(void)
+{
+	u32 didr;
+
+	/* Do we implement the extended CPUID interface? */
+	if (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
+		pr_warning("CPUID feature registers not supported. "
+				"Assuming v6 debug is present.\n");
+		return ARM_DEBUG_ARCH_V6;
+	}
+
+	ARM_DBG_READ(c0, 0, didr);
+	return (didr >> 16) & 0xf;
+}
+
+u8 arch_get_debug_arch(void)
+{
+	return debug_arch;
+}
+
+/* Determine number of BRP register available. */
+static int get_num_brp_resources(void)
+{
+	u32 didr;
+	ARM_DBG_READ(c0, 0, didr);
+	return ((didr >> 24) & 0xf) + 1;
+}
+
+/* Does this core support mismatch breakpoints? */
+static int core_has_mismatch_brps(void)
+{
+	return (get_debug_arch() >= ARM_DEBUG_ARCH_V7_ECP14 &&
+		get_num_brp_resources() > 1);
+}
+
+/* Determine number of usable WRPs available. */
+static int get_num_wrps(void)
+{
+	/*
+	 * FIXME: When a watchpoint fires, the only way to work out which
+	 * watchpoint it was is by disassembling the faulting instruction
+	 * and working out the address of the memory access.
+	 *
+	 * Furthermore, we can only do this if the watchpoint was precise
+	 * since imprecise watchpoints prevent us from calculating register
+	 * based addresses.
+	 *
+	 * Providing we have more than 1 breakpoint register, we only report
+	 * a single watchpoint register for the time being. This way, we always
+	 * know which watchpoint fired. In the future we can either add a
+	 * disassembler and address generation emulator, or we can insert a
+	 * check to see if the DFAR is set on watchpoint exception entry
+	 * [the ARM ARM states that the DFAR is UNKNOWN, but experience shows
+	 * that it is set on some implementations].
+	 */
+
+#if 0
+	int wrps;
+	u32 didr;
+	ARM_DBG_READ(c0, 0, didr);
+	wrps = ((didr >> 28) & 0xf) + 1;
+#endif
+	int wrps = 1;
+
+	if (core_has_mismatch_brps() && wrps >= get_num_brp_resources())
+		wrps = get_num_brp_resources() - 1;
+
+	return wrps;
+}
+
+/* We reserve one breakpoint for each watchpoint. */
+static int get_num_reserved_brps(void)
+{
+	if (core_has_mismatch_brps())
+		return get_num_wrps();
+	return 0;
+}
+
+/* Determine number of usable BRPs available. */
+static int get_num_brps(void)
+{
+	int brps = get_num_brp_resources();
+	if (core_has_mismatch_brps())
+		brps -= get_num_reserved_brps();
+	return brps;
+}
+
+int hw_breakpoint_slots(int type)
+{
+	/*
+	 * We can be called early, so don't rely on
+	 * our static variables being initialised.
+	 */
+	switch (type) {
+	case TYPE_INST:
+		return get_num_brps();
+	case TYPE_DATA:
+		return get_num_wrps();
+	default:
+		pr_warning("unknown slot type: %d\n", type);
+		return 0;
+	}
+}
+
 /*
  * In order to access the breakpoint/watchpoint control registers,
  * we must be running in debug monitor mode. Unfortunately, we can
@@ -326,7 +351,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
 		ctrl_base = ARM_BASE_BCR;
 		val_base = ARM_BASE_BVR;
 		slots = __get_cpu_var(bp_on_reg);
-		max_slots = core_num_brps - 1;
+		max_slots = core_num_brps;
 
 		if (bp_is_single_step(bp)) {
 			info->ctrl.mismatch = 1;
@@ -377,7 +402,7 @@ void arch_uninstall_hw_breakpoint(struct perf_event *bp)
 		/* Breakpoint */
 		base = ARM_BASE_BCR;
 		slots = __get_cpu_var(bp_on_reg);
-		max_slots = core_num_brps - 1;
+		max_slots = core_num_brps;
 
 		if (bp_is_single_step(bp)) {
 			i = max_slots;
@@ -611,7 +636,7 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
 	 * we can use the mismatch feature as a poor-man's hardware single-step.
 	 */
 	if (WARN_ONCE(!bp->overflow_handler &&
-		(arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_bps()),
+		(arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_brps()),
 			"overflow handler required but none found")) {
 		ret = -EINVAL;
 	}
@@ -698,7 +723,7 @@ static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs)
 	/* The exception entry code places the amended lr in the PC. */
 	addr = regs->ARM_pc;
 
-	for (i = 0; i < core_num_brps; ++i) {
+	for (i = 0; i < core_num_brps + core_num_reserved_brps; ++i) {
 		rcu_read_lock();
 
 		bp = slots[i];
@@ -801,7 +826,8 @@ static void reset_ctrl_regs(void *unused)
 	if (enable_monitor_mode())
 		return;
 
-	for (i = 0; i < core_num_brps; ++i) {
+	/* We must also reset any reserved registers. */
+	for (i = 0; i < core_num_brps + core_num_reserved_brps; ++i) {
 		write_wb_reg(ARM_BASE_BCR + i, 0UL);
 		write_wb_reg(ARM_BASE_BVR + i, 0UL);
 	}
@@ -839,13 +865,15 @@ static int __init arch_hw_breakpoint_init(void)
 
 	/* Determine how many BRPs/WRPs are available. */
 	core_num_brps = get_num_brps();
+	core_num_reserved_brps = get_num_reserved_brps();
 	core_num_wrps = get_num_wrps();
 
 	pr_info("found %d breakpoint and %d watchpoint registers.\n",
-			core_num_brps, core_num_wrps);
+		core_num_brps + core_num_reserved_brps, core_num_wrps);
 
-	if (core_has_mismatch_bps())
-		pr_info("1 breakpoint reserved for watchpoint single-step.\n");
+	if (core_num_reserved_brps)
+		pr_info("%d breakpoint(s) reserved for watchpoint "
+				"single-step.\n", core_num_reserved_brps);
 
 	ARM_DBG_READ(c1, 0, dscr);
 	if (dscr & ARM_DSCR_HDBGEN) {