arch/loongarch/kernel/hw_breakpoint.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2022-2023 Loongson Technology Corporation Limited
  */
 #define pr_fmt(fmt) "hw-breakpoint: " fmt

 #include <linux/hw_breakpoint.h>
 #include <linux/kprobes.h>
 #include <linux/perf_event.h>

 #include <asm/hw_breakpoint.h>

 /* Breakpoint currently in use for each BRP. */
 static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[LOONGARCH_MAX_BRP]);

 /* Watchpoint currently in use for each WRP. */
 static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[LOONGARCH_MAX_WRP]);

 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_warn("unknown slot type: %d\n", type);
 		return 0;
 	}
 }

 #define READ_WB_REG_CASE(OFF, N, REG, T, VAL)		\
 	case (OFF + N):					\
 		LOONGARCH_CSR_WATCH_READ(N, REG, T, VAL);	\
 		break

 #define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL)		\
 	case (OFF + N):					\
 		LOONGARCH_CSR_WATCH_WRITE(N, REG, T, VAL);	\
 		break

 #define GEN_READ_WB_REG_CASES(OFF, REG, T, VAL)		\
 	READ_WB_REG_CASE(OFF, 0, REG, T, VAL);		\
 	READ_WB_REG_CASE(OFF, 1, REG, T, VAL);		\
 	READ_WB_REG_CASE(OFF, 2, REG, T, VAL);		\
 	READ_WB_REG_CASE(OFF, 3, REG, T, VAL);		\
 	READ_WB_REG_CASE(OFF, 4, REG, T, VAL);		\
 	READ_WB_REG_CASE(OFF, 5, REG, T, VAL);		\
 	READ_WB_REG_CASE(OFF, 6, REG, T, VAL);		\
 	READ_WB_REG_CASE(OFF, 7, REG, T, VAL);

 #define GEN_WRITE_WB_REG_CASES(OFF, REG, T, VAL)	\
 	WRITE_WB_REG_CASE(OFF, 0, REG, T, VAL);		\
 	WRITE_WB_REG_CASE(OFF, 1, REG, T, VAL);		\
 	WRITE_WB_REG_CASE(OFF, 2, REG, T, VAL);		\
 	WRITE_WB_REG_CASE(OFF, 3, REG, T, VAL);		\
 	WRITE_WB_REG_CASE(OFF, 4, REG, T, VAL);		\
 	WRITE_WB_REG_CASE(OFF, 5, REG, T, VAL);		\
 	WRITE_WB_REG_CASE(OFF, 6, REG, T, VAL);		\
 	WRITE_WB_REG_CASE(OFF, 7, REG, T, VAL);

 static u64 read_wb_reg(int reg, int n, int t)
 {
 	u64 val = 0;

 	switch (reg + n) {
 	GEN_READ_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
 	GEN_READ_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
 	GEN_READ_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
 	GEN_READ_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
 	default:
 		pr_warn("Attempt to read from unknown breakpoint register %d\n", n);
 	}

 	return val;
 }
 NOKPROBE_SYMBOL(read_wb_reg);

 static void write_wb_reg(int reg, int n, int t, u64 val)
 {
 	switch (reg + n) {
 	GEN_WRITE_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
 	GEN_WRITE_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
 	GEN_WRITE_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
 	GEN_WRITE_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
 	default:
 		pr_warn("Attempt to write to unknown breakpoint register %d\n", n);
 	}
 }
 NOKPROBE_SYMBOL(write_wb_reg);

 enum hw_breakpoint_ops {
 	HW_BREAKPOINT_INSTALL,
 	HW_BREAKPOINT_UNINSTALL,
 };

 /*
  * hw_breakpoint_slot_setup - Find and setup a perf slot according to operations
  *
  * @slots: pointer to array of slots
  * @max_slots: max number of slots
  * @bp: perf_event to setup
  * @ops: operation to be carried out on the slot
  *
  * Return:
  *	slot index on success
  *	-ENOSPC if no slot is available/matches
  *	-EINVAL on wrong operations parameter
  */

 static int hw_breakpoint_slot_setup(struct perf_event **slots, int max_slots,
 				    struct perf_event *bp, enum hw_breakpoint_ops ops)
 {
 	int i;
 	struct perf_event **slot;

 	for (i = 0; i < max_slots; ++i) {
 		slot = &slots[i];
 		switch (ops) {
 		case HW_BREAKPOINT_INSTALL:
 			if (!*slot) {
 				*slot = bp;
 				return i;
 			}
 			break;
 		case HW_BREAKPOINT_UNINSTALL:
 			if (*slot == bp) {
 				*slot = NULL;
 				return i;
 			}
 			break;
 		default:
 			pr_warn_once("Unhandled hw breakpoint ops %d\n", ops);
 			return -EINVAL;
 		}
 	}

 	return -ENOSPC;
 }

 void ptrace_hw_copy_thread(struct task_struct *tsk)
 {
 	memset(tsk->thread.hbp_break, 0, sizeof(tsk->thread.hbp_break));
 	memset(tsk->thread.hbp_watch, 0, sizeof(tsk->thread.hbp_watch));
 }

 /*
  * Unregister breakpoints from this task and reset the pointers in the thread_struct.
  */
 void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
 {
 	int i;
 	struct thread_struct *t = &tsk->thread;

 	for (i = 0; i < LOONGARCH_MAX_BRP; i++) {
 		if (t->hbp_break[i]) {
 			unregister_hw_breakpoint(t->hbp_break[i]);
 			t->hbp_break[i] = NULL;
 		}
 	}

 	for (i = 0; i < LOONGARCH_MAX_WRP; i++) {
 		if (t->hbp_watch[i]) {
 			unregister_hw_breakpoint(t->hbp_watch[i]);
 			t->hbp_watch[i] = NULL;
 		}
 	}
 }

 static int hw_breakpoint_control(struct perf_event *bp,
 				 enum hw_breakpoint_ops ops)
 {
 	u32 ctrl;
 	int i, max_slots, enable;
 	struct perf_event **slots;
 	struct arch_hw_breakpoint *info = counter_arch_bp(bp);

 	if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
 		/* Breakpoint */
 		slots = this_cpu_ptr(bp_on_reg);
 		max_slots = boot_cpu_data.watch_ireg_count;
 	} else {
 		/* Watchpoint */
 		slots = this_cpu_ptr(wp_on_reg);
 		max_slots = boot_cpu_data.watch_dreg_count;
 	}

 	i = hw_breakpoint_slot_setup(slots, max_slots, bp, ops);

 	if (WARN_ONCE(i < 0, "Can't find any breakpoint slot"))
 		return i;

 	switch (ops) {
 	case HW_BREAKPOINT_INSTALL:
 		/* Set the FWPnCFG/MWPnCFG 1~4 register. */
 		write_wb_reg(CSR_CFG_ADDR, i, 0, info->address);
 		write_wb_reg(CSR_CFG_ADDR, i, 1, info->address);
 		write_wb_reg(CSR_CFG_MASK, i, 0, info->mask);
 		write_wb_reg(CSR_CFG_MASK, i, 1, info->mask);
 		write_wb_reg(CSR_CFG_ASID, i, 0, 0);
 		write_wb_reg(CSR_CFG_ASID, i, 1, 0);
 		if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
 			write_wb_reg(CSR_CFG_CTRL, i, 0, CTRL_PLV_ENABLE);
 		} else {
 			ctrl = encode_ctrl_reg(info->ctrl);
 			write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl | CTRL_PLV_ENABLE |
 				     1 << MWPnCFG3_LoadEn | 1 << MWPnCFG3_StoreEn);
 		}
 		enable = csr_read64(LOONGARCH_CSR_CRMD);
 		csr_write64(CSR_CRMD_WE | enable, LOONGARCH_CSR_CRMD);
 		break;
 	case HW_BREAKPOINT_UNINSTALL:
 		/* Reset the FWPnCFG/MWPnCFG 1~4 register. */
 		write_wb_reg(CSR_CFG_ADDR, i, 0, 0);
 		write_wb_reg(CSR_CFG_ADDR, i, 1, 0);
 		write_wb_reg(CSR_CFG_MASK, i, 0, 0);
 		write_wb_reg(CSR_CFG_MASK, i, 1, 0);
 		write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
 		write_wb_reg(CSR_CFG_CTRL, i, 1, 0);
 		write_wb_reg(CSR_CFG_ASID, i, 0, 0);
 		write_wb_reg(CSR_CFG_ASID, i, 1, 0);
 		break;
 	}

 	return 0;
 }

 /*
  * Install a perf counter breakpoint.
  */
 int arch_install_hw_breakpoint(struct perf_event *bp)
 {
 	return hw_breakpoint_control(bp, HW_BREAKPOINT_INSTALL);
 }

 void arch_uninstall_hw_breakpoint(struct perf_event *bp)
 {
 	hw_breakpoint_control(bp, HW_BREAKPOINT_UNINSTALL);
 }

 static int get_hbp_len(u8 hbp_len)
 {
 	unsigned int len_in_bytes = 0;

 	switch (hbp_len) {
 	case LOONGARCH_BREAKPOINT_LEN_1:
 		len_in_bytes = 1;
 		break;
 	case LOONGARCH_BREAKPOINT_LEN_2:
 		len_in_bytes = 2;
 		break;
 	case LOONGARCH_BREAKPOINT_LEN_4:
 		len_in_bytes = 4;
 		break;
 	case LOONGARCH_BREAKPOINT_LEN_8:
 		len_in_bytes = 8;
 		break;
 	}

 	return len_in_bytes;
 }

 /*
  * Check whether bp virtual address is in kernel space.
  */
 int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
 {
 	unsigned int len;
 	unsigned long va;

 	va = hw->address;
 	len = get_hbp_len(hw->ctrl.len);

 	return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
 }

 /*
  * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
  * Hopefully this will disappear when ptrace can bypass the conversion
  * to generic breakpoint descriptions.
  */
 int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
 			   int *gen_len, int *gen_type, int *offset)
 {
 	/* Type */
 	switch (ctrl.type) {
 	case LOONGARCH_BREAKPOINT_EXECUTE:
 		*gen_type = HW_BREAKPOINT_X;
 		break;
 	case LOONGARCH_BREAKPOINT_LOAD:
 		*gen_type = HW_BREAKPOINT_R;
 		break;
 	case LOONGARCH_BREAKPOINT_STORE:
 		*gen_type = HW_BREAKPOINT_W;
 		break;
 	case LOONGARCH_BREAKPOINT_LOAD | LOONGARCH_BREAKPOINT_STORE:
 		*gen_type = HW_BREAKPOINT_RW;
 		break;
 	default:
 		return -EINVAL;
 	}

 	if (!ctrl.len)
 		return -EINVAL;

 	*offset = __ffs(ctrl.len);

 	/* Len */
 	switch (ctrl.len) {
 	case LOONGARCH_BREAKPOINT_LEN_1:
 		*gen_len = HW_BREAKPOINT_LEN_1;
 		break;
 	case LOONGARCH_BREAKPOINT_LEN_2:
 		*gen_len = HW_BREAKPOINT_LEN_2;
 		break;
 	case LOONGARCH_BREAKPOINT_LEN_4:
 		*gen_len = HW_BREAKPOINT_LEN_4;
 		break;
 	case LOONGARCH_BREAKPOINT_LEN_8:
 		*gen_len = HW_BREAKPOINT_LEN_8;
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 /*
  * Construct an arch_hw_breakpoint from a perf_event.
  */
 static int arch_build_bp_info(struct perf_event *bp,
 			      const struct perf_event_attr *attr,
 			      struct arch_hw_breakpoint *hw)
 {
 	/* Type */
 	switch (attr->bp_type) {
 	case HW_BREAKPOINT_X:
 		hw->ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
 		break;
 	case HW_BREAKPOINT_R:
 		hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD;
 		break;
 	case HW_BREAKPOINT_W:
 		hw->ctrl.type = LOONGARCH_BREAKPOINT_STORE;
 		break;
 	case HW_BREAKPOINT_RW:
 		hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD | LOONGARCH_BREAKPOINT_STORE;
 		break;
 	default:
 		return -EINVAL;
 	}

 	/* Len */
 	switch (attr->bp_len) {
 	case HW_BREAKPOINT_LEN_1:
 		hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_1;
 		break;
 	case HW_BREAKPOINT_LEN_2:
 		hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_2;
 		break;
 	case HW_BREAKPOINT_LEN_4:
 		hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
 		break;
 	case HW_BREAKPOINT_LEN_8:
 		hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_8;
 		break;
 	default:
 		return -EINVAL;
 	}

 	/* Address */
 	hw->address = attr->bp_addr;

 	return 0;
 }

 /*
  * Validate the arch-specific HW Breakpoint register settings.
  */
 int hw_breakpoint_arch_parse(struct perf_event *bp,
 			     const struct perf_event_attr *attr,
 			     struct arch_hw_breakpoint *hw)
 {
 	int ret;
 	u64 alignment_mask, offset;

 	/* Build the arch_hw_breakpoint. */
 	ret = arch_build_bp_info(bp, attr, hw);
 	if (ret)
 		return ret;

 	if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
 		alignment_mask = 0x7;
 	else
 		alignment_mask = 0x3;
 	offset = hw->address & alignment_mask;

 	hw->address &= ~alignment_mask;
 	hw->ctrl.len <<= offset;

 	return 0;
 }

 static void update_bp_registers(struct pt_regs *regs, int enable, int type)
 {
 	u32 ctrl;
 	int i, max_slots;
 	struct perf_event **slots;
 	struct arch_hw_breakpoint *info;

 	switch (type) {
 	case 0:
 		slots = this_cpu_ptr(bp_on_reg);
 		max_slots = boot_cpu_data.watch_ireg_count;
 		break;
 	case 1:
 		slots = this_cpu_ptr(wp_on_reg);
 		max_slots = boot_cpu_data.watch_dreg_count;
 		break;
 	default:
 		return;
 	}

 	for (i = 0; i < max_slots; ++i) {
 		if (!slots[i])
 			continue;

 		info = counter_arch_bp(slots[i]);
 		if (enable) {
 			if ((info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) && (type == 0)) {
 				write_wb_reg(CSR_CFG_CTRL, i, 0, CTRL_PLV_ENABLE);
 				write_wb_reg(CSR_CFG_CTRL, i, 0, CTRL_PLV_ENABLE);
 			} else {
 				ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
 				if (info->ctrl.type == LOONGARCH_BREAKPOINT_LOAD)
 					ctrl |= 0x1 << MWPnCFG3_LoadEn;
 				if (info->ctrl.type == LOONGARCH_BREAKPOINT_STORE)
 					ctrl |= 0x1 << MWPnCFG3_StoreEn;
 				write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
 			}
 			regs->csr_prmd |= CSR_PRMD_PWE;
 		} else {
 			if ((info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) && (type == 0)) {
 				write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
 			} else {
 				ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
 				if (info->ctrl.type == LOONGARCH_BREAKPOINT_LOAD)
 					ctrl &= ~0x1 << MWPnCFG3_LoadEn;
 				if (info->ctrl.type == LOONGARCH_BREAKPOINT_STORE)
 					ctrl &= ~0x1 << MWPnCFG3_StoreEn;
 				write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
 			}
 			regs->csr_prmd &= ~CSR_PRMD_PWE;
 		}
 	}
 }
 NOKPROBE_SYMBOL(update_bp_registers);

 /*
  * Debug exception handlers.
  */
 void breakpoint_handler(struct pt_regs *regs)
 {
 	int i;
 	struct perf_event *bp, **slots;

 	slots = this_cpu_ptr(bp_on_reg);

 	for (i = 0; i < boot_cpu_data.watch_ireg_count; ++i) {
 		bp = slots[i];
 		if (bp == NULL)
 			continue;
 		perf_bp_event(bp, regs);
 	}
 	update_bp_registers(regs, 0, 0);
 }
 NOKPROBE_SYMBOL(breakpoint_handler);

 void watchpoint_handler(struct pt_regs *regs)
 {
 	int i;
 	struct perf_event *wp, **slots;

 	slots = this_cpu_ptr(wp_on_reg);

 	for (i = 0; i < boot_cpu_data.watch_dreg_count; ++i) {
 		wp = slots[i];
 		if (wp == NULL)
 			continue;
 		perf_bp_event(wp, regs);
 	}
 	update_bp_registers(regs, 0, 1);
 }
 NOKPROBE_SYMBOL(watchpoint_handler);

 static int __init arch_hw_breakpoint_init(void)
 {
 	int cpu;

 	boot_cpu_data.watch_ireg_count = get_num_brps();
 	boot_cpu_data.watch_dreg_count = get_num_wrps();

 	pr_info("Found %d breakpoint and %d watchpoint registers.\n",
 		boot_cpu_data.watch_ireg_count, boot_cpu_data.watch_dreg_count);

 	for (cpu = 1; cpu < NR_CPUS; cpu++) {
 		cpu_data[cpu].watch_ireg_count = boot_cpu_data.watch_ireg_count;
 		cpu_data[cpu].watch_dreg_count = boot_cpu_data.watch_dreg_count;
 	}

 	return 0;
 }
 arch_initcall(arch_hw_breakpoint_init);

 void hw_breakpoint_thread_switch(struct task_struct *next)
 {
 	u64 addr, mask;
 	struct pt_regs *regs = task_pt_regs(next);

 	if (test_tsk_thread_flag(next, TIF_SINGLESTEP)) {
 		addr = read_wb_reg(CSR_CFG_ADDR, 0, 0);
 		mask = read_wb_reg(CSR_CFG_MASK, 0, 0);
 		if (!((regs->csr_era ^ addr) & ~mask))
 			csr_write32(CSR_FWPC_SKIP, LOONGARCH_CSR_FWPS);
 		regs->csr_prmd |= CSR_PRMD_PWE;
 	} else {
 		/* Update breakpoints */
 		update_bp_registers(regs, 1, 0);
 		/* Update watchpoints */
 		update_bp_registers(regs, 1, 1);
 	}
 }

 void hw_breakpoint_pmu_read(struct perf_event *bp)
 {
 }

 /*
  * Dummy function to register with die_notifier.
  */
 int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
 				    unsigned long val, void *data)
 {
 	return NOTIFY_DONE;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) 2022-2023 Loongson Technology Corporation Limited
	*/
	#define pr_fmt(fmt) "hw-breakpoint: " fmt

	#include <linux/hw_breakpoint.h>
	#include <linux/kprobes.h>
	#include <linux/perf_event.h>

	#include <asm/hw_breakpoint.h>

	/* Breakpoint currently in use for each BRP. */
	static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[LOONGARCH_MAX_BRP]);

	/* Watchpoint currently in use for each WRP. */
	static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[LOONGARCH_MAX_WRP]);

	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_warn("unknown slot type: %d\n", type);
	return 0;
	}
	}

	#define READ_WB_REG_CASE(OFF, N, REG, T, VAL) \
	case (OFF + N): \
	LOONGARCH_CSR_WATCH_READ(N, REG, T, VAL); \
	break

	#define WRITE_WB_REG_CASE(OFF, N, REG, T, VAL) \
	case (OFF + N): \
	LOONGARCH_CSR_WATCH_WRITE(N, REG, T, VAL); \
	break

	#define GEN_READ_WB_REG_CASES(OFF, REG, T, VAL) \
	READ_WB_REG_CASE(OFF, 0, REG, T, VAL); \
	READ_WB_REG_CASE(OFF, 1, REG, T, VAL); \
	READ_WB_REG_CASE(OFF, 2, REG, T, VAL); \
	READ_WB_REG_CASE(OFF, 3, REG, T, VAL); \
	READ_WB_REG_CASE(OFF, 4, REG, T, VAL); \
	READ_WB_REG_CASE(OFF, 5, REG, T, VAL); \
	READ_WB_REG_CASE(OFF, 6, REG, T, VAL); \
	READ_WB_REG_CASE(OFF, 7, REG, T, VAL);

	#define GEN_WRITE_WB_REG_CASES(OFF, REG, T, VAL) \
	WRITE_WB_REG_CASE(OFF, 0, REG, T, VAL); \
	WRITE_WB_REG_CASE(OFF, 1, REG, T, VAL); \
	WRITE_WB_REG_CASE(OFF, 2, REG, T, VAL); \
	WRITE_WB_REG_CASE(OFF, 3, REG, T, VAL); \
	WRITE_WB_REG_CASE(OFF, 4, REG, T, VAL); \
	WRITE_WB_REG_CASE(OFF, 5, REG, T, VAL); \
	WRITE_WB_REG_CASE(OFF, 6, REG, T, VAL); \
	WRITE_WB_REG_CASE(OFF, 7, REG, T, VAL);

	static u64 read_wb_reg(int reg, int n, int t)
	{
	u64 val = 0;

	switch (reg + n) {
	GEN_READ_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
	GEN_READ_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
	GEN_READ_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
	GEN_READ_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
	default:
	pr_warn("Attempt to read from unknown breakpoint register %d\n", n);
	}

	return val;
	}
	NOKPROBE_SYMBOL(read_wb_reg);

	static void write_wb_reg(int reg, int n, int t, u64 val)
	{
	switch (reg + n) {
	GEN_WRITE_WB_REG_CASES(CSR_CFG_ADDR, ADDR, t, val);
	GEN_WRITE_WB_REG_CASES(CSR_CFG_MASK, MASK, t, val);
	GEN_WRITE_WB_REG_CASES(CSR_CFG_CTRL, CTRL, t, val);
	GEN_WRITE_WB_REG_CASES(CSR_CFG_ASID, ASID, t, val);
	default:
	pr_warn("Attempt to write to unknown breakpoint register %d\n", n);
	}
	}
	NOKPROBE_SYMBOL(write_wb_reg);

	enum hw_breakpoint_ops {
	HW_BREAKPOINT_INSTALL,
	HW_BREAKPOINT_UNINSTALL,
	};

	/*
	* hw_breakpoint_slot_setup - Find and setup a perf slot according to operations
	*
	* @slots: pointer to array of slots
	* @max_slots: max number of slots
	* @bp: perf_event to setup
	* @ops: operation to be carried out on the slot
	*
	* Return:
	* slot index on success
	* -ENOSPC if no slot is available/matches
	* -EINVAL on wrong operations parameter
	*/

	static int hw_breakpoint_slot_setup(struct perf_event **slots, int max_slots,
	struct perf_event *bp, enum hw_breakpoint_ops ops)
	{
	int i;
	struct perf_event **slot;

	for (i = 0; i < max_slots; ++i) {
	slot = &slots[i];
	switch (ops) {
	case HW_BREAKPOINT_INSTALL:
	if (!*slot) {
	*slot = bp;
	return i;
	}
	break;
	case HW_BREAKPOINT_UNINSTALL:
	if (*slot == bp) {
	*slot = NULL;
	return i;
	}
	break;
	default:
	pr_warn_once("Unhandled hw breakpoint ops %d\n", ops);
	return -EINVAL;
	}
	}

	return -ENOSPC;
	}

	void ptrace_hw_copy_thread(struct task_struct *tsk)
	{
	memset(tsk->thread.hbp_break, 0, sizeof(tsk->thread.hbp_break));
	memset(tsk->thread.hbp_watch, 0, sizeof(tsk->thread.hbp_watch));
	}

	/*
	* Unregister breakpoints from this task and reset the pointers in the thread_struct.
	*/
	void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
	{
	int i;
	struct thread_struct *t = &tsk->thread;

	for (i = 0; i < LOONGARCH_MAX_BRP; i++) {
	if (t->hbp_break[i]) {
	unregister_hw_breakpoint(t->hbp_break[i]);
	t->hbp_break[i] = NULL;
	}
	}

	for (i = 0; i < LOONGARCH_MAX_WRP; i++) {
	if (t->hbp_watch[i]) {
	unregister_hw_breakpoint(t->hbp_watch[i]);
	t->hbp_watch[i] = NULL;
	}
	}
	}

	static int hw_breakpoint_control(struct perf_event *bp,
	enum hw_breakpoint_ops ops)
	{
	u32 ctrl;
	int i, max_slots, enable;
	struct perf_event **slots;
	struct arch_hw_breakpoint *info = counter_arch_bp(bp);

	if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
	/* Breakpoint */
	slots = this_cpu_ptr(bp_on_reg);
	max_slots = boot_cpu_data.watch_ireg_count;
	} else {
	/* Watchpoint */
	slots = this_cpu_ptr(wp_on_reg);
	max_slots = boot_cpu_data.watch_dreg_count;
	}

	i = hw_breakpoint_slot_setup(slots, max_slots, bp, ops);

	if (WARN_ONCE(i < 0, "Can't find any breakpoint slot"))
	return i;

	switch (ops) {
	case HW_BREAKPOINT_INSTALL:
	/* Set the FWPnCFG/MWPnCFG 1~4 register. */
	write_wb_reg(CSR_CFG_ADDR, i, 0, info->address);
	write_wb_reg(CSR_CFG_ADDR, i, 1, info->address);
	write_wb_reg(CSR_CFG_MASK, i, 0, info->mask);
	write_wb_reg(CSR_CFG_MASK, i, 1, info->mask);
	write_wb_reg(CSR_CFG_ASID, i, 0, 0);
	write_wb_reg(CSR_CFG_ASID, i, 1, 0);
	if (info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) {
	write_wb_reg(CSR_CFG_CTRL, i, 0, CTRL_PLV_ENABLE);
	} else {
	ctrl = encode_ctrl_reg(info->ctrl);
	write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl \| CTRL_PLV_ENABLE \|
	1 << MWPnCFG3_LoadEn \| 1 << MWPnCFG3_StoreEn);
	}
	enable = csr_read64(LOONGARCH_CSR_CRMD);
	csr_write64(CSR_CRMD_WE \| enable, LOONGARCH_CSR_CRMD);
	break;
	case HW_BREAKPOINT_UNINSTALL:
	/* Reset the FWPnCFG/MWPnCFG 1~4 register. */
	write_wb_reg(CSR_CFG_ADDR, i, 0, 0);
	write_wb_reg(CSR_CFG_ADDR, i, 1, 0);
	write_wb_reg(CSR_CFG_MASK, i, 0, 0);
	write_wb_reg(CSR_CFG_MASK, i, 1, 0);
	write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
	write_wb_reg(CSR_CFG_CTRL, i, 1, 0);
	write_wb_reg(CSR_CFG_ASID, i, 0, 0);
	write_wb_reg(CSR_CFG_ASID, i, 1, 0);
	break;
	}

	return 0;
	}

	/*
	* Install a perf counter breakpoint.
	*/
	int arch_install_hw_breakpoint(struct perf_event *bp)
	{
	return hw_breakpoint_control(bp, HW_BREAKPOINT_INSTALL);
	}

	void arch_uninstall_hw_breakpoint(struct perf_event *bp)
	{
	hw_breakpoint_control(bp, HW_BREAKPOINT_UNINSTALL);
	}

	static int get_hbp_len(u8 hbp_len)
	{
	unsigned int len_in_bytes = 0;

	switch (hbp_len) {
	case LOONGARCH_BREAKPOINT_LEN_1:
	len_in_bytes = 1;
	break;
	case LOONGARCH_BREAKPOINT_LEN_2:
	len_in_bytes = 2;
	break;
	case LOONGARCH_BREAKPOINT_LEN_4:
	len_in_bytes = 4;
	break;
	case LOONGARCH_BREAKPOINT_LEN_8:
	len_in_bytes = 8;
	break;
	}

	return len_in_bytes;
	}

	/*
	* Check whether bp virtual address is in kernel space.
	*/
	int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
	{
	unsigned int len;
	unsigned long va;

	va = hw->address;
	len = get_hbp_len(hw->ctrl.len);

	return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
	}

	/*
	* Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
	* Hopefully this will disappear when ptrace can bypass the conversion
	* to generic breakpoint descriptions.
	*/
	int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
	int gen_len, int gen_type, int *offset)
	{
	/* Type */
	switch (ctrl.type) {
	case LOONGARCH_BREAKPOINT_EXECUTE:
	*gen_type = HW_BREAKPOINT_X;
	break;
	case LOONGARCH_BREAKPOINT_LOAD:
	*gen_type = HW_BREAKPOINT_R;
	break;
	case LOONGARCH_BREAKPOINT_STORE:
	*gen_type = HW_BREAKPOINT_W;
	break;
	case LOONGARCH_BREAKPOINT_LOAD \| LOONGARCH_BREAKPOINT_STORE:
	*gen_type = HW_BREAKPOINT_RW;
	break;
	default:
	return -EINVAL;
	}

	if (!ctrl.len)
	return -EINVAL;

	*offset = __ffs(ctrl.len);

	/* Len */
	switch (ctrl.len) {
	case LOONGARCH_BREAKPOINT_LEN_1:
	*gen_len = HW_BREAKPOINT_LEN_1;
	break;
	case LOONGARCH_BREAKPOINT_LEN_2:
	*gen_len = HW_BREAKPOINT_LEN_2;
	break;
	case LOONGARCH_BREAKPOINT_LEN_4:
	*gen_len = HW_BREAKPOINT_LEN_4;
	break;
	case LOONGARCH_BREAKPOINT_LEN_8:
	*gen_len = HW_BREAKPOINT_LEN_8;
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	/*
	* Construct an arch_hw_breakpoint from a perf_event.
	*/
	static int arch_build_bp_info(struct perf_event *bp,
	const struct perf_event_attr *attr,
	struct arch_hw_breakpoint *hw)
	{
	/* Type */
	switch (attr->bp_type) {
	case HW_BREAKPOINT_X:
	hw->ctrl.type = LOONGARCH_BREAKPOINT_EXECUTE;
	break;
	case HW_BREAKPOINT_R:
	hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD;
	break;
	case HW_BREAKPOINT_W:
	hw->ctrl.type = LOONGARCH_BREAKPOINT_STORE;
	break;
	case HW_BREAKPOINT_RW:
	hw->ctrl.type = LOONGARCH_BREAKPOINT_LOAD \| LOONGARCH_BREAKPOINT_STORE;
	break;
	default:
	return -EINVAL;
	}

	/* Len */
	switch (attr->bp_len) {
	case HW_BREAKPOINT_LEN_1:
	hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_1;
	break;
	case HW_BREAKPOINT_LEN_2:
	hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_2;
	break;
	case HW_BREAKPOINT_LEN_4:
	hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_4;
	break;
	case HW_BREAKPOINT_LEN_8:
	hw->ctrl.len = LOONGARCH_BREAKPOINT_LEN_8;
	break;
	default:
	return -EINVAL;
	}

	/* Address */
	hw->address = attr->bp_addr;

	return 0;
	}

	/*
	* Validate the arch-specific HW Breakpoint register settings.
	*/
	int hw_breakpoint_arch_parse(struct perf_event *bp,
	const struct perf_event_attr *attr,
	struct arch_hw_breakpoint *hw)
	{
	int ret;
	u64 alignment_mask, offset;

	/* Build the arch_hw_breakpoint. */
	ret = arch_build_bp_info(bp, attr, hw);
	if (ret)
	return ret;

	if (hw->ctrl.type != LOONGARCH_BREAKPOINT_EXECUTE)
	alignment_mask = 0x7;
	else
	alignment_mask = 0x3;
	offset = hw->address & alignment_mask;

	hw->address &= ~alignment_mask;
	hw->ctrl.len <<= offset;

	return 0;
	}

	static void update_bp_registers(struct pt_regs *regs, int enable, int type)
	{
	u32 ctrl;
	int i, max_slots;
	struct perf_event **slots;
	struct arch_hw_breakpoint *info;

	switch (type) {
	case 0:
	slots = this_cpu_ptr(bp_on_reg);
	max_slots = boot_cpu_data.watch_ireg_count;
	break;
	case 1:
	slots = this_cpu_ptr(wp_on_reg);
	max_slots = boot_cpu_data.watch_dreg_count;
	break;
	default:
	return;
	}

	for (i = 0; i < max_slots; ++i) {
	if (!slots[i])
	continue;

	info = counter_arch_bp(slots[i]);
	if (enable) {
	if ((info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) && (type == 0)) {
	write_wb_reg(CSR_CFG_CTRL, i, 0, CTRL_PLV_ENABLE);
	write_wb_reg(CSR_CFG_CTRL, i, 0, CTRL_PLV_ENABLE);
	} else {
	ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
	if (info->ctrl.type == LOONGARCH_BREAKPOINT_LOAD)
	ctrl \|= 0x1 << MWPnCFG3_LoadEn;
	if (info->ctrl.type == LOONGARCH_BREAKPOINT_STORE)
	ctrl \|= 0x1 << MWPnCFG3_StoreEn;
	write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
	}
	regs->csr_prmd \|= CSR_PRMD_PWE;
	} else {
	if ((info->ctrl.type == LOONGARCH_BREAKPOINT_EXECUTE) && (type == 0)) {
	write_wb_reg(CSR_CFG_CTRL, i, 0, 0);
	} else {
	ctrl = read_wb_reg(CSR_CFG_CTRL, i, 1);
	if (info->ctrl.type == LOONGARCH_BREAKPOINT_LOAD)
	ctrl &= ~0x1 << MWPnCFG3_LoadEn;
	if (info->ctrl.type == LOONGARCH_BREAKPOINT_STORE)
	ctrl &= ~0x1 << MWPnCFG3_StoreEn;
	write_wb_reg(CSR_CFG_CTRL, i, 1, ctrl);
	}
	regs->csr_prmd &= ~CSR_PRMD_PWE;
	}
	}
	}
	NOKPROBE_SYMBOL(update_bp_registers);

	/*
	* Debug exception handlers.
	*/
	void breakpoint_handler(struct pt_regs *regs)
	{
	int i;
	struct perf_event bp, *slots;

	slots = this_cpu_ptr(bp_on_reg);

	for (i = 0; i < boot_cpu_data.watch_ireg_count; ++i) {
	bp = slots[i];
	if (bp == NULL)
	continue;
	perf_bp_event(bp, regs);
	}
	update_bp_registers(regs, 0, 0);
	}
	NOKPROBE_SYMBOL(breakpoint_handler);

	void watchpoint_handler(struct pt_regs *regs)
	{
	int i;
	struct perf_event wp, *slots;

	slots = this_cpu_ptr(wp_on_reg);

	for (i = 0; i < boot_cpu_data.watch_dreg_count; ++i) {
	wp = slots[i];
	if (wp == NULL)
	continue;
	perf_bp_event(wp, regs);
	}
	update_bp_registers(regs, 0, 1);
	}
	NOKPROBE_SYMBOL(watchpoint_handler);

	static int __init arch_hw_breakpoint_init(void)
	{
	int cpu;

	boot_cpu_data.watch_ireg_count = get_num_brps();
	boot_cpu_data.watch_dreg_count = get_num_wrps();

	pr_info("Found %d breakpoint and %d watchpoint registers.\n",
	boot_cpu_data.watch_ireg_count, boot_cpu_data.watch_dreg_count);

	for (cpu = 1; cpu < NR_CPUS; cpu++) {
	cpu_data[cpu].watch_ireg_count = boot_cpu_data.watch_ireg_count;
	cpu_data[cpu].watch_dreg_count = boot_cpu_data.watch_dreg_count;
	}

	return 0;
	}
	arch_initcall(arch_hw_breakpoint_init);

	void hw_breakpoint_thread_switch(struct task_struct *next)
	{
	u64 addr, mask;
	struct pt_regs *regs = task_pt_regs(next);

	if (test_tsk_thread_flag(next, TIF_SINGLESTEP)) {
	addr = read_wb_reg(CSR_CFG_ADDR, 0, 0);
	mask = read_wb_reg(CSR_CFG_MASK, 0, 0);
	if (!((regs->csr_era ^ addr) & ~mask))
	csr_write32(CSR_FWPC_SKIP, LOONGARCH_CSR_FWPS);
	regs->csr_prmd \|= CSR_PRMD_PWE;
	} else {
	/* Update breakpoints */
	update_bp_registers(regs, 1, 0);
	/* Update watchpoints */
	update_bp_registers(regs, 1, 1);
	}
	}

	void hw_breakpoint_pmu_read(struct perf_event *bp)
	{
	}

	/*
	* Dummy function to register with die_notifier.
	*/
	int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
	unsigned long val, void *data)
	{
	return NOTIFY_DONE;
	}