1 files changed, 416 insertions, 0 deletions
diff --git a/arch/sh/kernel/hw_breakpoint.c b/arch/sh/kernel/hw_breakpoint.c
new file mode 100644
index 000000000000..ff3cb3d7df8f
--- /dev/null
+++ b/arch/sh/kernel/hw_breakpoint.c
@@ -0,0 +1,416 @@
+/*
+ * arch/sh/kernel/hw_breakpoint.c
+ *
+ * Unified kernel/user-space hardware breakpoint facility for the on-chip UBC.
+ *
+ * Copyright (C) 2009  Paul Mundt
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#include <linux/init.h>
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/percpu.h>
+#include <linux/kallsyms.h>
+#include <linux/notifier.h>
+#include <linux/kprobes.h>
+#include <linux/kdebug.h>
+#include <linux/io.h>
+#include <asm/hw_breakpoint.h>
+#include <asm/mmu_context.h>
+
+struct ubc_context {
+	unsigned long pc;
+	unsigned long state;
+};
+
+/* Per cpu ubc channel state */
+static DEFINE_PER_CPU(struct ubc_context, ubc_ctx[HBP_NUM]);
+
+/*
+ * Stores the breakpoints currently in use on each breakpoint address
+ * register for each cpus
+ */
+static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);
+
+static int __init ubc_init(void)
+{
+	__raw_writel(0, UBC_CAMR0);
+	__raw_writel(0, UBC_CBR0);
+	__raw_writel(0, UBC_CBCR);
+
+	__raw_writel(UBC_CRR_BIE | UBC_CRR_PCB, UBC_CRR0);
+
+	/* dummy read for write posting */
+	(void)__raw_readl(UBC_CRR0);
+
+	return 0;
+}
+arch_initcall(ubc_init);
+
+/*
+ * Install a perf counter breakpoint.
+ *
+ * We seek a free UBC channel and use it for this breakpoint.
+ *
+ * Atomic: we hold the counter->ctx->lock and we only handle variables
+ * and registers local to this cpu.
+ */
+int arch_install_hw_breakpoint(struct perf_event *bp)
+{
+	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+	struct ubc_context *ubc_ctx;
+	int i;
+
+	for (i = 0; i < HBP_NUM; i++) {
+		struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
+
+		if (!*slot) {
+			*slot = bp;
+			break;
+		}
+	}
+
+	if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
+		return -EBUSY;
+
+	ubc_ctx = &__get_cpu_var(ubc_ctx[i]);
+
+	ubc_ctx->pc = info->address;
+	ubc_ctx->state = info->len | info->type;
+
+	__raw_writel(UBC_CBR_CE | ubc_ctx->state, UBC_CBR0);
+	__raw_writel(ubc_ctx->pc, UBC_CAR0);
+
+	return 0;
+}
+
+/*
+ * Uninstall the breakpoint contained in the given counter.
+ *
+ * First we search the debug address register it uses and then we disable
+ * it.
+ *
+ * Atomic: we hold the counter->ctx->lock and we only handle variables
+ * and registers local to this cpu.
+ */
+void arch_uninstall_hw_breakpoint(struct perf_event *bp)
+{
+	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+	struct ubc_context *ubc_ctx;
+	int i;
+
+	for (i = 0; i < HBP_NUM; i++) {
+		struct perf_event **slot = &__get_cpu_var(bp_per_reg[i]);
+
+		if (*slot == bp) {
+			*slot = NULL;
+			break;
+		}
+	}
+
+	if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
+		return;
+
+	ubc_ctx = &__get_cpu_var(ubc_ctx[i]);
+	ubc_ctx->pc = 0;
+	ubc_ctx->state &= ~(info->len | info->type);
+
+	__raw_writel(ubc_ctx->pc, UBC_CBR0);
+	__raw_writel(ubc_ctx->state, UBC_CAR0);
+}
+
+static int get_hbp_len(u16 hbp_len)
+{
+	unsigned int len_in_bytes = 0;
+
+	switch (hbp_len) {
+	case SH_BREAKPOINT_LEN_1:
+		len_in_bytes = 1;
+		break;
+	case SH_BREAKPOINT_LEN_2:
+		len_in_bytes = 2;
+		break;
+	case SH_BREAKPOINT_LEN_4:
+		len_in_bytes = 4;
+		break;
+	case SH_BREAKPOINT_LEN_8:
+		len_in_bytes = 8;
+		break;
+	}
+	return len_in_bytes;
+}
+
+/*
+ * Check for virtual address in user space.
+ */
+int arch_check_va_in_userspace(unsigned long va, u16 hbp_len)
+{
+	unsigned int len;
+
+	len = get_hbp_len(hbp_len);
+
+	return (va <= TASK_SIZE - len);
+}
+
+/*
+ * Check for virtual address in kernel space.
+ */
+static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
+{
+	unsigned int len;
+
+	len = get_hbp_len(hbp_len);
+
+	return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+}
+
+/*
+ * Store a breakpoint's encoded address, length, and type.
+ */
+static int arch_store_info(struct perf_event *bp)
+{
+	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+
+	/*
+	 * User-space requests will always have the address field populated
+	 * For kernel-addresses, either the address or symbol name can be
+	 * specified.
+	 */
+	if (info->name)
+		info->address = (unsigned long)kallsyms_lookup_name(info->name);
+	if (info->address) {
+		info->asid = get_asid();
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+int arch_bp_generic_fields(int sh_len, int sh_type,
+			   int *gen_len, int *gen_type)
+{
+	/* Len */
+	switch (sh_len) {
+	case SH_BREAKPOINT_LEN_1:
+		*gen_len = HW_BREAKPOINT_LEN_1;
+		break;
+	case SH_BREAKPOINT_LEN_2:
+		*gen_len = HW_BREAKPOINT_LEN_2;
+		break;
+	case SH_BREAKPOINT_LEN_4:
+		*gen_len = HW_BREAKPOINT_LEN_4;
+		break;
+	case SH_BREAKPOINT_LEN_8:
+		*gen_len = HW_BREAKPOINT_LEN_8;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Type */
+	switch (sh_type) {
+	case SH_BREAKPOINT_READ:
+		*gen_type = HW_BREAKPOINT_R;
+	case SH_BREAKPOINT_WRITE:
+		*gen_type = HW_BREAKPOINT_W;
+		break;
+	case SH_BREAKPOINT_RW:
+		*gen_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int arch_build_bp_info(struct perf_event *bp)
+{
+	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+
+	info->address = bp->attr.bp_addr;
+
+	/* Len */
+	switch (bp->attr.bp_len) {
+	case HW_BREAKPOINT_LEN_1:
+		info->len = SH_BREAKPOINT_LEN_1;
+		break;
+	case HW_BREAKPOINT_LEN_2:
+		info->len = SH_BREAKPOINT_LEN_2;
+		break;
+	case HW_BREAKPOINT_LEN_4:
+		info->len = SH_BREAKPOINT_LEN_4;
+		break;
+	case HW_BREAKPOINT_LEN_8:
+		info->len = SH_BREAKPOINT_LEN_8;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Type */
+	switch (bp->attr.bp_type) {
+	case HW_BREAKPOINT_R:
+		info->type = SH_BREAKPOINT_READ;
+		break;
+	case HW_BREAKPOINT_W:
+		info->type = SH_BREAKPOINT_WRITE;
+		break;
+	case HW_BREAKPOINT_W | HW_BREAKPOINT_R:
+		info->type = SH_BREAKPOINT_RW;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Validate the arch-specific HW Breakpoint register settings
+ */
+int arch_validate_hwbkpt_settings(struct perf_event *bp,
+				  struct task_struct *tsk)
+{
+	struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+	unsigned int align;
+	int ret;
+
+	ret = arch_build_bp_info(bp);
+	if (ret)
+		return ret;
+
+	ret = -EINVAL;
+
+	switch (info->len) {
+	case SH_BREAKPOINT_LEN_1:
+		align = 0;
+		break;
+	case SH_BREAKPOINT_LEN_2:
+		align = 1;
+		break;
+	case SH_BREAKPOINT_LEN_4:
+		align = 3;
+		break;
+	case SH_BREAKPOINT_LEN_8:
+		align = 7;
+		break;
+	default:
+		return ret;
+	}
+
+	if (bp->callback)
+		ret = arch_store_info(bp);
+
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Check that the low-order bits of the address are appropriate
+	 * for the alignment implied by len.
+	 */
+	if (info->address & align)
+		return -EINVAL;
+
+	/* Check that the virtual address is in the proper range */
+	if (tsk) {
+		if (!arch_check_va_in_userspace(info->address, info->len))
+			return -EFAULT;
+	} else {
+		if (!arch_check_va_in_kernelspace(info->address, info->len))
+			return -EFAULT;
+	}
+
+	return 0;
+}
+
+/*
+ * Release the user breakpoints used by ptrace
+ */
+void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
+{
+	int i;
+	struct thread_struct *t = &tsk->thread;
+
+	for (i = 0; i < HBP_NUM; i++) {
+		unregister_hw_breakpoint(t->ptrace_bps[i]);
+		t->ptrace_bps[i] = NULL;
+	}
+}
+
+static int __kprobes hw_breakpoint_handler(struct die_args *args)
+{
+	int cpu, i, rc = NOTIFY_STOP;
+	struct perf_event *bp;
+	unsigned long val;
+
+	val = __raw_readl(UBC_CBR0);
+	__raw_writel(val & ~UBC_CBR_CE, UBC_CBR0);
+
+	cpu = get_cpu();
+	for (i = 0; i < HBP_NUM; i++) {
+		/*
+		 * The counter may be concurrently released but that can only
+		 * occur from a call_rcu() path. We can then safely fetch
+		 * the breakpoint, use its callback, touch its counter
+		 * while we are in an rcu_read_lock() path.
+		 */
+		rcu_read_lock();
+
+		bp = per_cpu(bp_per_reg[i], cpu);
+		if (bp) {
+			rc = NOTIFY_DONE;
+		} else {
+			rcu_read_unlock();
+			break;
+		}
+
+		(bp->callback)(bp, args->regs);
+
+		rcu_read_unlock();
+	}
+
+	if (bp) {
+		struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+
+		__raw_writel(UBC_CBR_CE | info->len | info->type, UBC_CBR0);
+		__raw_writel(info->address, UBC_CAR0);
+	}
+
+	put_cpu();
+
+	return rc;
+}
+
+BUILD_TRAP_HANDLER(breakpoint)
+{
+	unsigned long ex = lookup_exception_vector();
+	TRAP_HANDLER_DECL;
+
+	notify_die(DIE_BREAKPOINT, "breakpoint", regs, 0, ex, SIGTRAP);
+}
+
+/*
+ * Handle debug exception notifications.
+ */
+int __kprobes hw_breakpoint_exceptions_notify(struct notifier_block *unused,
+				    unsigned long val, void *data)
+{
+	if (val != DIE_BREAKPOINT)
+		return NOTIFY_DONE;
+
+	return hw_breakpoint_handler(data);
+}
+
+void hw_breakpoint_pmu_read(struct perf_event *bp)
+{
+	/* TODO */
+}
+
+void hw_breakpoint_pmu_unthrottle(struct perf_event *bp)
+{
+	/* TODO */
+}