| /* |
| * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, |
| * using the CPU's debug registers. |
| * |
| * Copyright (C) 2012 ARM Limited |
| * Author: Will Deacon <will.deacon@arm.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #define pr_fmt(fmt) "hw-breakpoint: " fmt |
| |
| #include <linux/compat.h> |
| #include <linux/cpu_pm.h> |
| #include <linux/errno.h> |
| #include <linux/hw_breakpoint.h> |
| #include <linux/perf_event.h> |
| #include <linux/ptrace.h> |
| #include <linux/smp.h> |
| |
| #include <asm/compat.h> |
| #include <asm/current.h> |
| #include <asm/debug-monitors.h> |
| #include <asm/hw_breakpoint.h> |
| #include <asm/traps.h> |
| #include <asm/cputype.h> |
| #include <asm/system_misc.h> |
| |
| /* Breakpoint currently in use for each BRP. */ |
| static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]); |
| |
| /* Watchpoint currently in use for each WRP. */ |
| static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]); |
| |
| /* Currently stepping a per-CPU kernel breakpoint. */ |
| static DEFINE_PER_CPU(int, stepping_kernel_bp); |
| |
| /* Number of BRP/WRP registers on this CPU. */ |
| static int core_num_brps; |
| static int core_num_wrps; |
| |
| 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; |
| } |
| } |
| |
| #define READ_WB_REG_CASE(OFF, N, REG, VAL) \ |
| case (OFF + N): \ |
| AARCH64_DBG_READ(N, REG, VAL); \ |
| break |
| |
| #define WRITE_WB_REG_CASE(OFF, N, REG, VAL) \ |
| case (OFF + N): \ |
| AARCH64_DBG_WRITE(N, REG, VAL); \ |
| break |
| |
| #define GEN_READ_WB_REG_CASES(OFF, REG, VAL) \ |
| READ_WB_REG_CASE(OFF, 0, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 1, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 2, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 3, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 4, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 5, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 6, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 7, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 8, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 9, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 10, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 11, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 12, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 13, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 14, REG, VAL); \ |
| READ_WB_REG_CASE(OFF, 15, REG, VAL) |
| |
| #define GEN_WRITE_WB_REG_CASES(OFF, REG, VAL) \ |
| WRITE_WB_REG_CASE(OFF, 0, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 1, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 2, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 3, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 4, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 5, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 6, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 7, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 8, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 9, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 10, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 11, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 12, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 13, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 14, REG, VAL); \ |
| WRITE_WB_REG_CASE(OFF, 15, REG, VAL) |
| |
| static u64 read_wb_reg(int reg, int n) |
| { |
| u64 val = 0; |
| |
| switch (reg + n) { |
| GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_BVR, AARCH64_DBG_REG_NAME_BVR, val); |
| GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_BCR, AARCH64_DBG_REG_NAME_BCR, val); |
| GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_WVR, AARCH64_DBG_REG_NAME_WVR, val); |
| GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_WCR, AARCH64_DBG_REG_NAME_WCR, val); |
| default: |
| pr_warning("attempt to read from unknown breakpoint register %d\n", n); |
| } |
| |
| return val; |
| } |
| |
| static void write_wb_reg(int reg, int n, u64 val) |
| { |
| switch (reg + n) { |
| GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_BVR, AARCH64_DBG_REG_NAME_BVR, val); |
| GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_BCR, AARCH64_DBG_REG_NAME_BCR, val); |
| GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_WVR, AARCH64_DBG_REG_NAME_WVR, val); |
| GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_WCR, AARCH64_DBG_REG_NAME_WCR, val); |
| default: |
| pr_warning("attempt to write to unknown breakpoint register %d\n", n); |
| } |
| isb(); |
| } |
| |
| /* |
| * Convert a breakpoint privilege level to the corresponding exception |
| * level. |
| */ |
| static enum dbg_active_el debug_exception_level(int privilege) |
| { |
| switch (privilege) { |
| case AARCH64_BREAKPOINT_EL0: |
| return DBG_ACTIVE_EL0; |
| case AARCH64_BREAKPOINT_EL1: |
| return DBG_ACTIVE_EL1; |
| default: |
| pr_warning("invalid breakpoint privilege level %d\n", privilege); |
| return -EINVAL; |
| } |
| } |
| |
| enum hw_breakpoint_ops { |
| HW_BREAKPOINT_INSTALL, |
| HW_BREAKPOINT_UNINSTALL, |
| HW_BREAKPOINT_RESTORE |
| }; |
| |
| static int is_compat_bp(struct perf_event *bp) |
| { |
| struct task_struct *tsk = bp->hw.target; |
| |
| /* |
| * tsk can be NULL for per-cpu (non-ptrace) breakpoints. |
| * In this case, use the native interface, since we don't have |
| * the notion of a "compat CPU" and could end up relying on |
| * deprecated behaviour if we use unaligned watchpoints in |
| * AArch64 state. |
| */ |
| return tsk && is_compat_thread(task_thread_info(tsk)); |
| } |
| |
| /** |
| * 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; |
| case HW_BREAKPOINT_RESTORE: |
| if (*slot == bp) |
| return i; |
| break; |
| default: |
| pr_warn_once("Unhandled hw breakpoint ops %d\n", ops); |
| return -EINVAL; |
| } |
| } |
| return -ENOSPC; |
| } |
| |
| static int hw_breakpoint_control(struct perf_event *bp, |
| enum hw_breakpoint_ops ops) |
| { |
| struct arch_hw_breakpoint *info = counter_arch_bp(bp); |
| struct perf_event **slots; |
| struct debug_info *debug_info = ¤t->thread.debug; |
| int i, max_slots, ctrl_reg, val_reg, reg_enable; |
| enum dbg_active_el dbg_el = debug_exception_level(info->ctrl.privilege); |
| u32 ctrl; |
| |
| if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) { |
| /* Breakpoint */ |
| ctrl_reg = AARCH64_DBG_REG_BCR; |
| val_reg = AARCH64_DBG_REG_BVR; |
| slots = this_cpu_ptr(bp_on_reg); |
| max_slots = core_num_brps; |
| reg_enable = !debug_info->bps_disabled; |
| } else { |
| /* Watchpoint */ |
| ctrl_reg = AARCH64_DBG_REG_WCR; |
| val_reg = AARCH64_DBG_REG_WVR; |
| slots = this_cpu_ptr(wp_on_reg); |
| max_slots = core_num_wrps; |
| reg_enable = !debug_info->wps_disabled; |
| } |
| |
| 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: |
| /* |
| * Ensure debug monitors are enabled at the correct exception |
| * level. |
| */ |
| enable_debug_monitors(dbg_el); |
| /* Fall through */ |
| case HW_BREAKPOINT_RESTORE: |
| /* Setup the address register. */ |
| write_wb_reg(val_reg, i, info->address); |
| |
| /* Setup the control register. */ |
| ctrl = encode_ctrl_reg(info->ctrl); |
| write_wb_reg(ctrl_reg, i, |
| reg_enable ? ctrl | 0x1 : ctrl & ~0x1); |
| break; |
| case HW_BREAKPOINT_UNINSTALL: |
| /* Reset the control register. */ |
| write_wb_reg(ctrl_reg, i, 0); |
| |
| /* |
| * Release the debug monitors for the correct exception |
| * level. |
| */ |
| disable_debug_monitors(dbg_el); |
| 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 ARM_BREAKPOINT_LEN_1: |
| len_in_bytes = 1; |
| break; |
| case ARM_BREAKPOINT_LEN_2: |
| len_in_bytes = 2; |
| break; |
| case ARM_BREAKPOINT_LEN_4: |
| len_in_bytes = 4; |
| break; |
| case ARM_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 perf_event *bp) |
| { |
| unsigned int len; |
| unsigned long va; |
| struct arch_hw_breakpoint *info = counter_arch_bp(bp); |
| |
| va = info->address; |
| len = get_hbp_len(info->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) |
| { |
| /* Type */ |
| switch (ctrl.type) { |
| case ARM_BREAKPOINT_EXECUTE: |
| *gen_type = HW_BREAKPOINT_X; |
| break; |
| case ARM_BREAKPOINT_LOAD: |
| *gen_type = HW_BREAKPOINT_R; |
| break; |
| case ARM_BREAKPOINT_STORE: |
| *gen_type = HW_BREAKPOINT_W; |
| break; |
| case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE: |
| *gen_type = HW_BREAKPOINT_RW; |
| break; |
| default: |
| return -EINVAL; |
| } |
| |
| /* Len */ |
| switch (ctrl.len) { |
| case ARM_BREAKPOINT_LEN_1: |
| *gen_len = HW_BREAKPOINT_LEN_1; |
| break; |
| case ARM_BREAKPOINT_LEN_2: |
| *gen_len = HW_BREAKPOINT_LEN_2; |
| break; |
| case ARM_BREAKPOINT_LEN_4: |
| *gen_len = HW_BREAKPOINT_LEN_4; |
| break; |
| case ARM_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) |
| { |
| struct arch_hw_breakpoint *info = counter_arch_bp(bp); |
| |
| /* Type */ |
| switch (bp->attr.bp_type) { |
| case HW_BREAKPOINT_X: |
| info->ctrl.type = ARM_BREAKPOINT_EXECUTE; |
| break; |
| case HW_BREAKPOINT_R: |
| info->ctrl.type = ARM_BREAKPOINT_LOAD; |
| break; |
| case HW_BREAKPOINT_W: |
| info->ctrl.type = ARM_BREAKPOINT_STORE; |
| break; |
| case HW_BREAKPOINT_RW: |
| info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE; |
| break; |
| default: |
| return -EINVAL; |
| } |
| |
| /* Len */ |
| switch (bp->attr.bp_len) { |
| case HW_BREAKPOINT_LEN_1: |
| info->ctrl.len = ARM_BREAKPOINT_LEN_1; |
| break; |
| case HW_BREAKPOINT_LEN_2: |
| info->ctrl.len = ARM_BREAKPOINT_LEN_2; |
| break; |
| case HW_BREAKPOINT_LEN_4: |
| info->ctrl.len = ARM_BREAKPOINT_LEN_4; |
| break; |
| case HW_BREAKPOINT_LEN_8: |
| info->ctrl.len = ARM_BREAKPOINT_LEN_8; |
| break; |
| default: |
| return -EINVAL; |
| } |
| |
| /* |
| * On AArch64, we only permit breakpoints of length 4, whereas |
| * AArch32 also requires breakpoints of length 2 for Thumb. |
| * Watchpoints can be of length 1, 2, 4 or 8 bytes. |
| */ |
| if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) { |
| if (is_compat_bp(bp)) { |
| if (info->ctrl.len != ARM_BREAKPOINT_LEN_2 && |
| info->ctrl.len != ARM_BREAKPOINT_LEN_4) |
| return -EINVAL; |
| } else if (info->ctrl.len != ARM_BREAKPOINT_LEN_4) { |
| /* |
| * FIXME: Some tools (I'm looking at you perf) assume |
| * that breakpoints should be sizeof(long). This |
| * is nonsense. For now, we fix up the parameter |
| * but we should probably return -EINVAL instead. |
| */ |
| info->ctrl.len = ARM_BREAKPOINT_LEN_4; |
| } |
| } |
| |
| /* Address */ |
| info->address = bp->attr.bp_addr; |
| |
| /* |
| * Privilege |
| * Note that we disallow combined EL0/EL1 breakpoints because |
| * that would complicate the stepping code. |
| */ |
| if (arch_check_bp_in_kernelspace(bp)) |
| info->ctrl.privilege = AARCH64_BREAKPOINT_EL1; |
| else |
| info->ctrl.privilege = AARCH64_BREAKPOINT_EL0; |
| |
| /* Enabled? */ |
| info->ctrl.enabled = !bp->attr.disabled; |
| |
| return 0; |
| } |
| |
| /* |
| * Validate the arch-specific HW Breakpoint register settings. |
| */ |
| int arch_validate_hwbkpt_settings(struct perf_event *bp) |
| { |
| struct arch_hw_breakpoint *info = counter_arch_bp(bp); |
| int ret; |
| u64 alignment_mask, offset; |
| |
| /* Build the arch_hw_breakpoint. */ |
| ret = arch_build_bp_info(bp); |
| if (ret) |
| return ret; |
| |
| /* |
| * Check address alignment. |
| * We don't do any clever alignment correction for watchpoints |
| * because using 64-bit unaligned addresses is deprecated for |
| * AArch64. |
| * |
| * AArch32 tasks expect some simple alignment fixups, so emulate |
| * that here. |
| */ |
| if (is_compat_bp(bp)) { |
| if (info->ctrl.len == ARM_BREAKPOINT_LEN_8) |
| alignment_mask = 0x7; |
| else |
| alignment_mask = 0x3; |
| offset = info->address & alignment_mask; |
| switch (offset) { |
| case 0: |
| /* Aligned */ |
| break; |
| case 1: |
| /* Allow single byte watchpoint. */ |
| if (info->ctrl.len == ARM_BREAKPOINT_LEN_1) |
| break; |
| case 2: |
| /* Allow halfword watchpoints and breakpoints. */ |
| if (info->ctrl.len == ARM_BREAKPOINT_LEN_2) |
| break; |
| default: |
| return -EINVAL; |
| } |
| |
| info->address &= ~alignment_mask; |
| info->ctrl.len <<= offset; |
| } else { |
| if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) |
| alignment_mask = 0x3; |
| else |
| alignment_mask = 0x7; |
| if (info->address & alignment_mask) |
| return -EINVAL; |
| } |
| |
| /* |
| * Disallow per-task kernel breakpoints since these would |
| * complicate the stepping code. |
| */ |
| if (info->ctrl.privilege == AARCH64_BREAKPOINT_EL1 && bp->hw.target) |
| return -EINVAL; |
| |
| return 0; |
| } |
| |
| /* |
| * Enable/disable all of the breakpoints active at the specified |
| * exception level at the register level. |
| * This is used when single-stepping after a breakpoint exception. |
| */ |
| static void toggle_bp_registers(int reg, enum dbg_active_el el, int enable) |
| { |
| int i, max_slots, privilege; |
| u32 ctrl; |
| struct perf_event **slots; |
| |
| switch (reg) { |
| case AARCH64_DBG_REG_BCR: |
| slots = this_cpu_ptr(bp_on_reg); |
| max_slots = core_num_brps; |
| break; |
| case AARCH64_DBG_REG_WCR: |
| slots = this_cpu_ptr(wp_on_reg); |
| max_slots = core_num_wrps; |
| break; |
| default: |
| return; |
| } |
| |
| for (i = 0; i < max_slots; ++i) { |
| if (!slots[i]) |
| continue; |
| |
| privilege = counter_arch_bp(slots[i])->ctrl.privilege; |
| if (debug_exception_level(privilege) != el) |
| continue; |
| |
| ctrl = read_wb_reg(reg, i); |
| if (enable) |
| ctrl |= 0x1; |
| else |
| ctrl &= ~0x1; |
| write_wb_reg(reg, i, ctrl); |
| } |
| } |
| |
| /* |
| * Debug exception handlers. |
| */ |
| static int breakpoint_handler(unsigned long unused, unsigned int esr, |
| struct pt_regs *regs) |
| { |
| int i, step = 0, *kernel_step; |
| u32 ctrl_reg; |
| u64 addr, val; |
| struct perf_event *bp, **slots; |
| struct debug_info *debug_info; |
| struct arch_hw_breakpoint_ctrl ctrl; |
| |
| slots = this_cpu_ptr(bp_on_reg); |
| addr = instruction_pointer(regs); |
| debug_info = ¤t->thread.debug; |
| |
| for (i = 0; i < core_num_brps; ++i) { |
| rcu_read_lock(); |
| |
| bp = slots[i]; |
| |
| if (bp == NULL) |
| goto unlock; |
| |
| /* Check if the breakpoint value matches. */ |
| val = read_wb_reg(AARCH64_DBG_REG_BVR, i); |
| if (val != (addr & ~0x3)) |
| goto unlock; |
| |
| /* Possible match, check the byte address select to confirm. */ |
| ctrl_reg = read_wb_reg(AARCH64_DBG_REG_BCR, i); |
| decode_ctrl_reg(ctrl_reg, &ctrl); |
| if (!((1 << (addr & 0x3)) & ctrl.len)) |
| goto unlock; |
| |
| counter_arch_bp(bp)->trigger = addr; |
| perf_bp_event(bp, regs); |
| |
| /* Do we need to handle the stepping? */ |
| if (is_default_overflow_handler(bp)) |
| step = 1; |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| if (!step) |
| return 0; |
| |
| if (user_mode(regs)) { |
| debug_info->bps_disabled = 1; |
| toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL0, 0); |
| |
| /* If we're already stepping a watchpoint, just return. */ |
| if (debug_info->wps_disabled) |
| return 0; |
| |
| if (test_thread_flag(TIF_SINGLESTEP)) |
| debug_info->suspended_step = 1; |
| else |
| user_enable_single_step(current); |
| } else { |
| toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL1, 0); |
| kernel_step = this_cpu_ptr(&stepping_kernel_bp); |
| |
| if (*kernel_step != ARM_KERNEL_STEP_NONE) |
| return 0; |
| |
| if (kernel_active_single_step()) { |
| *kernel_step = ARM_KERNEL_STEP_SUSPEND; |
| } else { |
| *kernel_step = ARM_KERNEL_STEP_ACTIVE; |
| kernel_enable_single_step(regs); |
| } |
| } |
| |
| return 0; |
| } |
| |
| static int watchpoint_handler(unsigned long addr, unsigned int esr, |
| struct pt_regs *regs) |
| { |
| int i, step = 0, *kernel_step, access; |
| u32 ctrl_reg; |
| u64 val, alignment_mask; |
| struct perf_event *wp, **slots; |
| struct debug_info *debug_info; |
| struct arch_hw_breakpoint *info; |
| struct arch_hw_breakpoint_ctrl ctrl; |
| |
| slots = this_cpu_ptr(wp_on_reg); |
| debug_info = ¤t->thread.debug; |
| |
| for (i = 0; i < core_num_wrps; ++i) { |
| rcu_read_lock(); |
| |
| wp = slots[i]; |
| |
| if (wp == NULL) |
| goto unlock; |
| |
| info = counter_arch_bp(wp); |
| /* AArch32 watchpoints are either 4 or 8 bytes aligned. */ |
| if (is_compat_task()) { |
| if (info->ctrl.len == ARM_BREAKPOINT_LEN_8) |
| alignment_mask = 0x7; |
| else |
| alignment_mask = 0x3; |
| } else { |
| alignment_mask = 0x7; |
| } |
| |
| /* Check if the watchpoint value matches. */ |
| val = read_wb_reg(AARCH64_DBG_REG_WVR, i); |
| if (val != (addr & ~alignment_mask)) |
| goto unlock; |
| |
| /* Possible match, check the byte address select to confirm. */ |
| ctrl_reg = read_wb_reg(AARCH64_DBG_REG_WCR, i); |
| decode_ctrl_reg(ctrl_reg, &ctrl); |
| if (!((1 << (addr & alignment_mask)) & ctrl.len)) |
| goto unlock; |
| |
| /* |
| * Check that the access type matches. |
| * 0 => load, otherwise => store |
| */ |
| access = (esr & AARCH64_ESR_ACCESS_MASK) ? HW_BREAKPOINT_W : |
| HW_BREAKPOINT_R; |
| if (!(access & hw_breakpoint_type(wp))) |
| goto unlock; |
| |
| info->trigger = addr; |
| perf_bp_event(wp, regs); |
| |
| /* Do we need to handle the stepping? */ |
| if (is_default_overflow_handler(wp)) |
| step = 1; |
| |
| unlock: |
| rcu_read_unlock(); |
| } |
| |
| if (!step) |
| return 0; |
| |
| /* |
| * We always disable EL0 watchpoints because the kernel can |
| * cause these to fire via an unprivileged access. |
| */ |
| toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 0); |
| |
| if (user_mode(regs)) { |
| debug_info->wps_disabled = 1; |
| |
| /* If we're already stepping a breakpoint, just return. */ |
| if (debug_info->bps_disabled) |
| return 0; |
| |
| if (test_thread_flag(TIF_SINGLESTEP)) |
| debug_info->suspended_step = 1; |
| else |
| user_enable_single_step(current); |
| } else { |
| toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL1, 0); |
| kernel_step = this_cpu_ptr(&stepping_kernel_bp); |
| |
| if (*kernel_step != ARM_KERNEL_STEP_NONE) |
| return 0; |
| |
| if (kernel_active_single_step()) { |
| *kernel_step = ARM_KERNEL_STEP_SUSPEND; |
| } else { |
| *kernel_step = ARM_KERNEL_STEP_ACTIVE; |
| kernel_enable_single_step(regs); |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Handle single-step exception. |
| */ |
| int reinstall_suspended_bps(struct pt_regs *regs) |
| { |
| struct debug_info *debug_info = ¤t->thread.debug; |
| int handled_exception = 0, *kernel_step; |
| |
| kernel_step = this_cpu_ptr(&stepping_kernel_bp); |
| |
| /* |
| * Called from single-step exception handler. |
| * Return 0 if execution can resume, 1 if a SIGTRAP should be |
| * reported. |
| */ |
| if (user_mode(regs)) { |
| if (debug_info->bps_disabled) { |
| debug_info->bps_disabled = 0; |
| toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL0, 1); |
| handled_exception = 1; |
| } |
| |
| if (debug_info->wps_disabled) { |
| debug_info->wps_disabled = 0; |
| toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1); |
| handled_exception = 1; |
| } |
| |
| if (handled_exception) { |
| if (debug_info->suspended_step) { |
| debug_info->suspended_step = 0; |
| /* Allow exception handling to fall-through. */ |
| handled_exception = 0; |
| } else { |
| user_disable_single_step(current); |
| } |
| } |
| } else if (*kernel_step != ARM_KERNEL_STEP_NONE) { |
| toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL1, 1); |
| toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL1, 1); |
| |
| if (!debug_info->wps_disabled) |
| toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1); |
| |
| if (*kernel_step != ARM_KERNEL_STEP_SUSPEND) { |
| kernel_disable_single_step(); |
| handled_exception = 1; |
| } else { |
| handled_exception = 0; |
| } |
| |
| *kernel_step = ARM_KERNEL_STEP_NONE; |
| } |
| |
| return !handled_exception; |
| } |
| |
| /* |
| * Context-switcher for restoring suspended breakpoints. |
| */ |
| void hw_breakpoint_thread_switch(struct task_struct *next) |
| { |
| /* |
| * current next |
| * disabled: 0 0 => The usual case, NOTIFY_DONE |
| * 0 1 => Disable the registers |
| * 1 0 => Enable the registers |
| * 1 1 => NOTIFY_DONE. per-task bps will |
| * get taken care of by perf. |
| */ |
| |
| struct debug_info *current_debug_info, *next_debug_info; |
| |
| current_debug_info = ¤t->thread.debug; |
| next_debug_info = &next->thread.debug; |
| |
| /* Update breakpoints. */ |
| if (current_debug_info->bps_disabled != next_debug_info->bps_disabled) |
| toggle_bp_registers(AARCH64_DBG_REG_BCR, |
| DBG_ACTIVE_EL0, |
| !next_debug_info->bps_disabled); |
| |
| /* Update watchpoints. */ |
| if (current_debug_info->wps_disabled != next_debug_info->wps_disabled) |
| toggle_bp_registers(AARCH64_DBG_REG_WCR, |
| DBG_ACTIVE_EL0, |
| !next_debug_info->wps_disabled); |
| } |
| |
| /* |
| * CPU initialisation. |
| */ |
| static void hw_breakpoint_reset(void *unused) |
| { |
| int i; |
| struct perf_event **slots; |
| /* |
| * When a CPU goes through cold-boot, it does not have any installed |
| * slot, so it is safe to share the same function for restoring and |
| * resetting breakpoints; when a CPU is hotplugged in, it goes |
| * through the slots, which are all empty, hence it just resets control |
| * and value for debug registers. |
| * When this function is triggered on warm-boot through a CPU PM |
| * notifier some slots might be initialized; if so they are |
| * reprogrammed according to the debug slots content. |
| */ |
| for (slots = this_cpu_ptr(bp_on_reg), i = 0; i < core_num_brps; ++i) { |
| if (slots[i]) { |
| hw_breakpoint_control(slots[i], HW_BREAKPOINT_RESTORE); |
| } else { |
| write_wb_reg(AARCH64_DBG_REG_BCR, i, 0UL); |
| write_wb_reg(AARCH64_DBG_REG_BVR, i, 0UL); |
| } |
| } |
| |
| for (slots = this_cpu_ptr(wp_on_reg), i = 0; i < core_num_wrps; ++i) { |
| if (slots[i]) { |
| hw_breakpoint_control(slots[i], HW_BREAKPOINT_RESTORE); |
| } else { |
| write_wb_reg(AARCH64_DBG_REG_WCR, i, 0UL); |
| write_wb_reg(AARCH64_DBG_REG_WVR, i, 0UL); |
| } |
| } |
| } |
| |
| static int hw_breakpoint_reset_notify(struct notifier_block *self, |
| unsigned long action, |
| void *hcpu) |
| { |
| if ((action & ~CPU_TASKS_FROZEN) == CPU_ONLINE) { |
| local_irq_disable(); |
| hw_breakpoint_reset(NULL); |
| local_irq_enable(); |
| } |
| return NOTIFY_OK; |
| } |
| |
| static struct notifier_block hw_breakpoint_reset_nb = { |
| .notifier_call = hw_breakpoint_reset_notify, |
| }; |
| |
| #ifdef CONFIG_CPU_PM |
| extern void cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *)); |
| #else |
| static inline void cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *)) |
| { |
| } |
| #endif |
| |
| /* |
| * One-time initialisation. |
| */ |
| static int __init arch_hw_breakpoint_init(void) |
| { |
| core_num_brps = get_num_brps(); |
| core_num_wrps = get_num_wrps(); |
| |
| pr_info("found %d breakpoint and %d watchpoint registers.\n", |
| core_num_brps, core_num_wrps); |
| |
| cpu_notifier_register_begin(); |
| |
| /* |
| * Reset the breakpoint resources. We assume that a halting |
| * debugger will leave the world in a nice state for us. |
| */ |
| smp_call_function(hw_breakpoint_reset, NULL, 1); |
| hw_breakpoint_reset(NULL); |
| |
| /* Register debug fault handlers. */ |
| hook_debug_fault_code(DBG_ESR_EVT_HWBP, breakpoint_handler, SIGTRAP, |
| TRAP_HWBKPT, "hw-breakpoint handler"); |
| hook_debug_fault_code(DBG_ESR_EVT_HWWP, watchpoint_handler, SIGTRAP, |
| TRAP_HWBKPT, "hw-watchpoint handler"); |
| |
| /* Register hotplug notifier. */ |
| __register_cpu_notifier(&hw_breakpoint_reset_nb); |
| |
| cpu_notifier_register_done(); |
| |
| /* Register cpu_suspend hw breakpoint restore hook */ |
| cpu_suspend_set_dbg_restorer(hw_breakpoint_reset); |
| |
| return 0; |
| } |
| arch_initcall(arch_hw_breakpoint_init); |
| |
| 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; |
| } |