From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- arch/arm/kernel/hw_breakpoint.c | 978 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 978 insertions(+) create mode 100644 arch/arm/kernel/hw_breakpoint.c (limited to 'arch/arm/kernel/hw_breakpoint.c') diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c new file mode 100644 index 00000000..87acc25d --- /dev/null +++ b/arch/arm/kernel/hw_breakpoint.c @@ -0,0 +1,978 @@ +/* + * 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, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) 2009, 2010 ARM Limited + * + * Author: Will Deacon + */ + +/* + * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, + * using the CPU's debug registers. + */ +#define pr_fmt(fmt) "hw-breakpoint: " fmt + +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include + +/* 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]); + +/* 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. */ +static u8 debug_arch; + +/* Maximum supported watchpoint length. */ +static u8 max_watchpoint_len; + +#define READ_WB_REG_CASE(OP2, M, VAL) \ + case ((OP2 << 4) + M): \ + ARM_DBG_READ(c ## M, OP2, VAL); \ + break + +#define WRITE_WB_REG_CASE(OP2, M, VAL) \ + case ((OP2 << 4) + M): \ + ARM_DBG_WRITE(c ## M, OP2, VAL);\ + break + +#define GEN_READ_WB_REG_CASES(OP2, VAL) \ + READ_WB_REG_CASE(OP2, 0, VAL); \ + READ_WB_REG_CASE(OP2, 1, VAL); \ + READ_WB_REG_CASE(OP2, 2, VAL); \ + READ_WB_REG_CASE(OP2, 3, VAL); \ + READ_WB_REG_CASE(OP2, 4, VAL); \ + READ_WB_REG_CASE(OP2, 5, VAL); \ + READ_WB_REG_CASE(OP2, 6, VAL); \ + READ_WB_REG_CASE(OP2, 7, VAL); \ + READ_WB_REG_CASE(OP2, 8, VAL); \ + READ_WB_REG_CASE(OP2, 9, VAL); \ + READ_WB_REG_CASE(OP2, 10, VAL); \ + READ_WB_REG_CASE(OP2, 11, VAL); \ + READ_WB_REG_CASE(OP2, 12, VAL); \ + READ_WB_REG_CASE(OP2, 13, VAL); \ + READ_WB_REG_CASE(OP2, 14, VAL); \ + READ_WB_REG_CASE(OP2, 15, VAL) + +#define GEN_WRITE_WB_REG_CASES(OP2, VAL) \ + WRITE_WB_REG_CASE(OP2, 0, VAL); \ + WRITE_WB_REG_CASE(OP2, 1, VAL); \ + WRITE_WB_REG_CASE(OP2, 2, VAL); \ + WRITE_WB_REG_CASE(OP2, 3, VAL); \ + WRITE_WB_REG_CASE(OP2, 4, VAL); \ + WRITE_WB_REG_CASE(OP2, 5, VAL); \ + WRITE_WB_REG_CASE(OP2, 6, VAL); \ + WRITE_WB_REG_CASE(OP2, 7, VAL); \ + WRITE_WB_REG_CASE(OP2, 8, VAL); \ + WRITE_WB_REG_CASE(OP2, 9, VAL); \ + WRITE_WB_REG_CASE(OP2, 10, VAL); \ + WRITE_WB_REG_CASE(OP2, 11, VAL); \ + WRITE_WB_REG_CASE(OP2, 12, VAL); \ + WRITE_WB_REG_CASE(OP2, 13, VAL); \ + WRITE_WB_REG_CASE(OP2, 14, VAL); \ + WRITE_WB_REG_CASE(OP2, 15, VAL) + +static u32 read_wb_reg(int n) +{ + u32 val = 0; + + switch (n) { + GEN_READ_WB_REG_CASES(ARM_OP2_BVR, val); + GEN_READ_WB_REG_CASES(ARM_OP2_BCR, val); + GEN_READ_WB_REG_CASES(ARM_OP2_WVR, val); + GEN_READ_WB_REG_CASES(ARM_OP2_WCR, val); + default: + pr_warning("attempt to read from unknown breakpoint " + "register %d\n", n); + } + + return val; +} + +static void write_wb_reg(int n, u32 val) +{ + switch (n) { + GEN_WRITE_WB_REG_CASES(ARM_OP2_BVR, val); + GEN_WRITE_WB_REG_CASES(ARM_OP2_BCR, val); + GEN_WRITE_WB_REG_CASES(ARM_OP2_WVR, val); + GEN_WRITE_WB_REG_CASES(ARM_OP2_WCR, val); + default: + pr_warning("attempt to write to unknown breakpoint " + "register %d\n", n); + } + isb(); +} + +/* Determine debug architecture. */ +static u8 get_debug_arch(void) +{ + u32 didr; + + /* Do we implement the extended CPUID interface? */ + if (WARN_ONCE((((read_cpuid_id() >> 16) & 0xf) != 0xf), + "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; +} + +static int debug_arch_supported(void) +{ + u8 arch = get_debug_arch(); + return arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14; +} + +/* 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; +} + +/* + * In order to access the breakpoint/watchpoint control registers, + * we must be running in debug monitor mode. Unfortunately, we can + * be put into halting debug mode at any time by an external debugger + * but there is nothing we can do to prevent that. + */ +static int enable_monitor_mode(void) +{ + u32 dscr; + int ret = 0; + + ARM_DBG_READ(c1, 0, dscr); + + /* Ensure that halting mode is disabled. */ + if (WARN_ONCE(dscr & ARM_DSCR_HDBGEN, + "halting debug mode enabled. Unable to access hardware resources.\n")) { + ret = -EPERM; + goto out; + } + + /* If monitor mode is already enabled, just return. */ + if (dscr & ARM_DSCR_MDBGEN) + goto out; + + /* Write to the corresponding DSCR. */ + switch (get_debug_arch()) { + case ARM_DEBUG_ARCH_V6: + case ARM_DEBUG_ARCH_V6_1: + ARM_DBG_WRITE(c1, 0, (dscr | ARM_DSCR_MDBGEN)); + break; + case ARM_DEBUG_ARCH_V7_ECP14: + ARM_DBG_WRITE(c2, 2, (dscr | ARM_DSCR_MDBGEN)); + break; + default: + ret = -ENODEV; + goto out; + } + + /* Check that the write made it through. */ + ARM_DBG_READ(c1, 0, dscr); + if (!(dscr & ARM_DSCR_MDBGEN)) + ret = -EPERM; + +out: + return ret; +} + +int hw_breakpoint_slots(int type) +{ + if (!debug_arch_supported()) + return 0; + + /* + * 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; + } +} + +/* + * Check if 8-bit byte-address select is available. + * This clobbers WRP 0. + */ +static u8 get_max_wp_len(void) +{ + u32 ctrl_reg; + struct arch_hw_breakpoint_ctrl ctrl; + u8 size = 4; + + if (debug_arch < ARM_DEBUG_ARCH_V7_ECP14) + goto out; + + memset(&ctrl, 0, sizeof(ctrl)); + ctrl.len = ARM_BREAKPOINT_LEN_8; + ctrl_reg = encode_ctrl_reg(ctrl); + + write_wb_reg(ARM_BASE_WVR, 0); + write_wb_reg(ARM_BASE_WCR, ctrl_reg); + if ((read_wb_reg(ARM_BASE_WCR) & ctrl_reg) == ctrl_reg) + size = 8; + +out: + return size; +} + +u8 arch_get_max_wp_len(void) +{ + return max_watchpoint_len; +} + +/* + * Install a perf counter breakpoint. + */ +int arch_install_hw_breakpoint(struct perf_event *bp) +{ + struct arch_hw_breakpoint *info = counter_arch_bp(bp); + struct perf_event **slot, **slots; + int i, max_slots, ctrl_base, val_base, ret = 0; + u32 addr, ctrl; + + /* Ensure that we are in monitor mode and halting mode is disabled. */ + ret = enable_monitor_mode(); + if (ret) + goto out; + + addr = info->address; + ctrl = encode_ctrl_reg(info->ctrl) | 0x1; + + if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) { + /* Breakpoint */ + ctrl_base = ARM_BASE_BCR; + val_base = ARM_BASE_BVR; + slots = (struct perf_event **)__get_cpu_var(bp_on_reg); + max_slots = core_num_brps; + if (info->step_ctrl.enabled) { + /* Override the breakpoint data with the step data. */ + addr = info->trigger & ~0x3; + ctrl = encode_ctrl_reg(info->step_ctrl); + } + } else { + /* Watchpoint */ + if (info->step_ctrl.enabled) { + /* Install into the reserved breakpoint region. */ + ctrl_base = ARM_BASE_BCR + core_num_brps; + val_base = ARM_BASE_BVR + core_num_brps; + /* Override the watchpoint data with the step data. */ + addr = info->trigger & ~0x3; + ctrl = encode_ctrl_reg(info->step_ctrl); + } else { + ctrl_base = ARM_BASE_WCR; + val_base = ARM_BASE_WVR; + } + slots = (struct perf_event **)__get_cpu_var(wp_on_reg); + max_slots = core_num_wrps; + } + + for (i = 0; i < max_slots; ++i) { + slot = &slots[i]; + + if (!*slot) { + *slot = bp; + break; + } + } + + if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot\n")) { + ret = -EBUSY; + goto out; + } + + /* Setup the address register. */ + write_wb_reg(val_base + i, addr); + + /* Setup the control register. */ + write_wb_reg(ctrl_base + i, ctrl); + +out: + return ret; +} + +void arch_uninstall_hw_breakpoint(struct perf_event *bp) +{ + struct arch_hw_breakpoint *info = counter_arch_bp(bp); + struct perf_event **slot, **slots; + int i, max_slots, base; + + if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) { + /* Breakpoint */ + base = ARM_BASE_BCR; + slots = (struct perf_event **)__get_cpu_var(bp_on_reg); + max_slots = core_num_brps; + } else { + /* Watchpoint */ + if (info->step_ctrl.enabled) + base = ARM_BASE_BCR + core_num_brps; + else + base = ARM_BASE_WCR; + slots = (struct perf_event **)__get_cpu_var(wp_on_reg); + max_slots = core_num_wrps; + } + + /* Remove the breakpoint. */ + for (i = 0; i < max_slots; ++i) { + slot = &slots[i]; + + if (*slot == bp) { + *slot = NULL; + break; + } + } + + if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot\n")) + return; + + /* Reset the control register. */ + write_wb_reg(base + i, 0); +} + +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; + if ((info->ctrl.type != ARM_BREAKPOINT_EXECUTE) + && max_watchpoint_len >= 8) + break; + default: + return -EINVAL; + } + + /* + * Breakpoints must be of length 2 (thumb) or 4 (ARM) bytes. + * Watchpoints can be of length 1, 2, 4 or 8 bytes if supported + * by the hardware and must be aligned to the appropriate number of + * bytes. + */ + if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE && + info->ctrl.len != ARM_BREAKPOINT_LEN_2 && + info->ctrl.len != ARM_BREAKPOINT_LEN_4) + return -EINVAL; + + /* Address */ + info->address = bp->attr.bp_addr; + + /* Privilege */ + info->ctrl.privilege = ARM_BREAKPOINT_USER; + if (arch_check_bp_in_kernelspace(bp)) + info->ctrl.privilege |= ARM_BREAKPOINT_PRIV; + + /* Enabled? */ + info->ctrl.enabled = !bp->attr.disabled; + + /* Mismatch */ + info->ctrl.mismatch = 0; + + 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 = 0; + u32 offset, alignment_mask = 0x3; + + /* Build the arch_hw_breakpoint. */ + ret = arch_build_bp_info(bp); + if (ret) + goto out; + + /* Check address alignment. */ + if (info->ctrl.len == ARM_BREAKPOINT_LEN_8) + alignment_mask = 0x7; + 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: + ret = -EINVAL; + goto out; + } + + info->address &= ~alignment_mask; + info->ctrl.len <<= offset; + + /* + * Currently we rely on an overflow handler to take + * care of single-stepping the breakpoint when it fires. + * In the case of userspace breakpoints on a core with V7 debug, + * we can use the mismatch feature as a poor-man's hardware + * single-step, but this only works for per-task breakpoints. + */ + if (WARN_ONCE(!bp->overflow_handler && + (arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_brps() + || !bp->hw.bp_target), + "overflow handler required but none found\n")) { + ret = -EINVAL; + } +out: + return ret; +} + +/* + * Enable/disable single-stepping over the breakpoint bp at address addr. + */ +static void enable_single_step(struct perf_event *bp, u32 addr) +{ + struct arch_hw_breakpoint *info = counter_arch_bp(bp); + + arch_uninstall_hw_breakpoint(bp); + info->step_ctrl.mismatch = 1; + info->step_ctrl.len = ARM_BREAKPOINT_LEN_4; + info->step_ctrl.type = ARM_BREAKPOINT_EXECUTE; + info->step_ctrl.privilege = info->ctrl.privilege; + info->step_ctrl.enabled = 1; + info->trigger = addr; + arch_install_hw_breakpoint(bp); +} + +static void disable_single_step(struct perf_event *bp) +{ + arch_uninstall_hw_breakpoint(bp); + counter_arch_bp(bp)->step_ctrl.enabled = 0; + arch_install_hw_breakpoint(bp); +} + +static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs) +{ + int i; + struct perf_event *wp, **slots; + struct arch_hw_breakpoint *info; + + slots = (struct perf_event **)__get_cpu_var(wp_on_reg); + + /* Without a disassembler, we can only handle 1 watchpoint. */ + BUG_ON(core_num_wrps > 1); + + for (i = 0; i < core_num_wrps; ++i) { + rcu_read_lock(); + + wp = slots[i]; + + if (wp == NULL) { + rcu_read_unlock(); + continue; + } + + /* + * The DFAR is an unknown value. Since we only allow a + * single watchpoint, we can set the trigger to the lowest + * possible faulting address. + */ + info = counter_arch_bp(wp); + info->trigger = wp->attr.bp_addr; + pr_debug("watchpoint fired: address = 0x%x\n", info->trigger); + perf_bp_event(wp, regs); + + /* + * If no overflow handler is present, insert a temporary + * mismatch breakpoint so we can single-step over the + * watchpoint trigger. + */ + if (!wp->overflow_handler) + enable_single_step(wp, instruction_pointer(regs)); + + rcu_read_unlock(); + } +} + +static void watchpoint_single_step_handler(unsigned long pc) +{ + int i; + struct perf_event *wp, **slots; + struct arch_hw_breakpoint *info; + + slots = (struct perf_event **)__get_cpu_var(wp_on_reg); + + for (i = 0; i < core_num_reserved_brps; ++i) { + rcu_read_lock(); + + wp = slots[i]; + + if (wp == NULL) + goto unlock; + + info = counter_arch_bp(wp); + if (!info->step_ctrl.enabled) + goto unlock; + + /* + * Restore the original watchpoint if we've completed the + * single-step. + */ + if (info->trigger != pc) + disable_single_step(wp); + +unlock: + rcu_read_unlock(); + } +} + +static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs) +{ + int i; + u32 ctrl_reg, val, addr; + struct perf_event *bp, **slots; + struct arch_hw_breakpoint *info; + struct arch_hw_breakpoint_ctrl ctrl; + + slots = (struct perf_event **)__get_cpu_var(bp_on_reg); + + /* The exception entry code places the amended lr in the PC. */ + addr = regs->ARM_pc; + + /* Check the currently installed breakpoints first. */ + for (i = 0; i < core_num_brps; ++i) { + rcu_read_lock(); + + bp = slots[i]; + + if (bp == NULL) + goto unlock; + + info = counter_arch_bp(bp); + + /* Check if the breakpoint value matches. */ + val = read_wb_reg(ARM_BASE_BVR + i); + if (val != (addr & ~0x3)) + goto mismatch; + + /* Possible match, check the byte address select to confirm. */ + ctrl_reg = read_wb_reg(ARM_BASE_BCR + i); + decode_ctrl_reg(ctrl_reg, &ctrl); + if ((1 << (addr & 0x3)) & ctrl.len) { + info->trigger = addr; + pr_debug("breakpoint fired: address = 0x%x\n", addr); + perf_bp_event(bp, regs); + if (!bp->overflow_handler) + enable_single_step(bp, addr); + goto unlock; + } + +mismatch: + /* If we're stepping a breakpoint, it can now be restored. */ + if (info->step_ctrl.enabled) + disable_single_step(bp); +unlock: + rcu_read_unlock(); + } + + /* Handle any pending watchpoint single-step breakpoints. */ + watchpoint_single_step_handler(addr); +} + +/* + * Called from either the Data Abort Handler [watchpoint] or the + * Prefetch Abort Handler [breakpoint] with preemption disabled. + */ +static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + int ret = 0; + u32 dscr; + + /* We must be called with preemption disabled. */ + WARN_ON(preemptible()); + + /* We only handle watchpoints and hardware breakpoints. */ + ARM_DBG_READ(c1, 0, dscr); + + /* Perform perf callbacks. */ + switch (ARM_DSCR_MOE(dscr)) { + case ARM_ENTRY_BREAKPOINT: + breakpoint_handler(addr, regs); + break; + case ARM_ENTRY_ASYNC_WATCHPOINT: + WARN(1, "Asynchronous watchpoint exception taken. Debugging results may be unreliable\n"); + case ARM_ENTRY_SYNC_WATCHPOINT: + watchpoint_handler(addr, regs); + break; + default: + ret = 1; /* Unhandled fault. */ + } + + /* + * Re-enable preemption after it was disabled in the + * low-level exception handling code. + */ + preempt_enable(); + + return ret; +} + +/* + * One-time initialisation. + */ +static void reset_ctrl_regs(void *info) +{ + int i, cpu = smp_processor_id(); + u32 dbg_power; + cpumask_t *cpumask = info; + + /* + * v7 debug contains save and restore registers so that debug state + * can be maintained across low-power modes without leaving the debug + * logic powered up. It is IMPLEMENTATION DEFINED whether we can access + * the debug registers out of reset, so we must unlock the OS Lock + * Access Register to avoid taking undefined instruction exceptions + * later on. + */ + if (debug_arch >= ARM_DEBUG_ARCH_V7_ECP14) { + /* + * Ensure sticky power-down is clear (i.e. debug logic is + * powered up). + */ + asm volatile("mrc p14, 0, %0, c1, c5, 4" : "=r" (dbg_power)); + if ((dbg_power & 0x1) == 0) { + pr_warning("CPU %d debug is powered down!\n", cpu); + cpumask_or(cpumask, cpumask, cpumask_of(cpu)); + return; + } + + /* + * Unconditionally clear the lock by writing a value + * other than 0xC5ACCE55 to the access register. + */ + asm volatile("mcr p14, 0, %0, c1, c0, 4" : : "r" (0)); + isb(); + + /* + * Clear any configured vector-catch events before + * enabling monitor mode. + */ + asm volatile("mcr p14, 0, %0, c0, c7, 0" : : "r" (0)); + isb(); + } + + if (enable_monitor_mode()) + return; + + /* 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); + } + + for (i = 0; i < core_num_wrps; ++i) { + write_wb_reg(ARM_BASE_WCR + i, 0UL); + write_wb_reg(ARM_BASE_WVR + i, 0UL); + } +} + +static int __cpuinit dbg_reset_notify(struct notifier_block *self, + unsigned long action, void *cpu) +{ + if (action == CPU_ONLINE) + smp_call_function_single((int)cpu, reset_ctrl_regs, NULL, 1); + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata dbg_reset_nb = { + .notifier_call = dbg_reset_notify, +}; + +static int __init arch_hw_breakpoint_init(void) +{ + u32 dscr; + cpumask_t cpumask = { CPU_BITS_NONE }; + + debug_arch = get_debug_arch(); + + if (!debug_arch_supported()) { + pr_info("debug architecture 0x%x unsupported.\n", debug_arch); + return 0; + } + + /* 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_reserved_brps, core_num_wrps); + + if (core_num_reserved_brps) + pr_info("%d breakpoint(s) reserved for watchpoint " + "single-step.\n", core_num_reserved_brps); + + /* + * Reset the breakpoint resources. We assume that a halting + * debugger will leave the world in a nice state for us. + */ + on_each_cpu(reset_ctrl_regs, &cpumask, 1); + if (!cpumask_empty(&cpumask)) { + core_num_brps = 0; + core_num_reserved_brps = 0; + core_num_wrps = 0; + return 0; + } + + ARM_DBG_READ(c1, 0, dscr); + if (dscr & ARM_DSCR_HDBGEN) { + max_watchpoint_len = 4; + pr_warning("halting debug mode enabled. Assuming maximum watchpoint size of %u bytes.\n", + max_watchpoint_len); + } else { + /* Work out the maximum supported watchpoint length. */ + max_watchpoint_len = get_max_wp_len(); + pr_info("maximum watchpoint size is %u bytes.\n", + max_watchpoint_len); + } + + /* Register debug fault handler. */ + hook_fault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT, + "watchpoint debug exception"); + hook_ifault_code(2, hw_breakpoint_pending, SIGTRAP, TRAP_HWBKPT, + "breakpoint debug exception"); + + /* Register hotplug notifier. */ + register_cpu_notifier(&dbg_reset_nb); + 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; +} -- cgit v1.2.3