diff options
| -rw-r--r-- | arch/arm/include/asm/hw_breakpoint.h | 123 | ||||
| -rw-r--r-- | arch/arm/kernel/hw_breakpoint.c | 849 |
2 files changed, 972 insertions, 0 deletions
diff --git a/arch/arm/include/asm/hw_breakpoint.h b/arch/arm/include/asm/hw_breakpoint.h new file mode 100644 index 00000000000..33048c700ca --- /dev/null +++ b/arch/arm/include/asm/hw_breakpoint.h @@ -0,0 +1,123 @@ +#ifndef _ARM_HW_BREAKPOINT_H +#define _ARM_HW_BREAKPOINT_H + +#ifdef __KERNEL__ +struct arch_hw_breakpoint_ctrl { + u32 __reserved : 9, + mismatch : 1, + : 9, + len : 8, + type : 2, + privilege : 2, + enabled : 1; +}; + +struct arch_hw_breakpoint { + u32 address; + u32 trigger; + struct perf_event *suspended_wp; + struct arch_hw_breakpoint_ctrl ctrl; +}; + +static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl) +{ + return (ctrl.mismatch << 22) | (ctrl.len << 5) | (ctrl.type << 3) | + (ctrl.privilege << 1) | ctrl.enabled; +} + +static inline void decode_ctrl_reg(u32 reg, + struct arch_hw_breakpoint_ctrl *ctrl) +{ + ctrl->enabled = reg & 0x1; + reg >>= 1; + ctrl->privilege = reg & 0x3; + reg >>= 2; + ctrl->type = reg & 0x3; + reg >>= 2; + ctrl->len = reg & 0xff; + reg >>= 17; + ctrl->mismatch = reg & 0x1; +} + +/* Debug architecture numbers. */ +#define ARM_DEBUG_ARCH_RESERVED 0 /* In case of ptrace ABI updates. */ +#define ARM_DEBUG_ARCH_V6 1 +#define ARM_DEBUG_ARCH_V6_1 2 +#define ARM_DEBUG_ARCH_V7_ECP14 3 +#define ARM_DEBUG_ARCH_V7_MM 4 + +/* Breakpoint */ +#define ARM_BREAKPOINT_EXECUTE 0 + +/* Watchpoints */ +#define ARM_BREAKPOINT_LOAD 1 +#define ARM_BREAKPOINT_STORE 2 + +/* Privilege Levels */ +#define ARM_BREAKPOINT_PRIV 1 +#define ARM_BREAKPOINT_USER 2 + +/* Lengths */ +#define ARM_BREAKPOINT_LEN_1 0x1 +#define ARM_BREAKPOINT_LEN_2 0x3 +#define ARM_BREAKPOINT_LEN_4 0xf +#define ARM_BREAKPOINT_LEN_8 0xff + +/* Limits */ +#define ARM_MAX_BRP 16 +#define ARM_MAX_WRP 16 +#define ARM_MAX_HBP_SLOTS (ARM_MAX_BRP + ARM_MAX_WRP) + +/* DSCR method of entry bits. */ +#define ARM_DSCR_MOE(x) ((x >> 2) & 0xf) +#define ARM_ENTRY_BREAKPOINT 0x1 +#define ARM_ENTRY_ASYNC_WATCHPOINT 0x2 +#define ARM_ENTRY_SYNC_WATCHPOINT 0xa + +/* DSCR monitor/halting bits. */ +#define ARM_DSCR_HDBGEN (1 << 14) +#define ARM_DSCR_MDBGEN (1 << 15) + +/* opcode2 numbers for the co-processor instructions. */ +#define ARM_OP2_BVR 4 +#define ARM_OP2_BCR 5 +#define ARM_OP2_WVR 6 +#define ARM_OP2_WCR 7 + +/* Base register numbers for the debug registers. */ +#define ARM_BASE_BVR 64 +#define ARM_BASE_BCR 80 +#define ARM_BASE_WVR 96 +#define ARM_BASE_WCR 112 + +/* Accessor macros for the debug registers. */ +#define ARM_DBG_READ(M, OP2, VAL) do {\ + asm volatile("mrc p14, 0, %0, c0," #M ", " #OP2 : "=r" (VAL));\ +} while (0) + +#define ARM_DBG_WRITE(M, OP2, VAL) do {\ + asm volatile("mcr p14, 0, %0, c0," #M ", " #OP2 : : "r" (VAL));\ +} while (0) + +struct notifier_block; +struct perf_event; +struct pmu; +struct task_struct; + +extern struct pmu perf_ops_bp; +extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl, + int *gen_len, int *gen_type); +extern int arch_check_bp_in_kernelspace(struct perf_event *bp); +extern int arch_validate_hwbkpt_settings(struct perf_event *bp); +extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused, + unsigned long val, void *data); +extern u8 arch_get_debug_arch(void); +extern u8 arch_get_max_wp_len(void); + +int arch_install_hw_breakpoint(struct perf_event *bp); +void arch_uninstall_hw_breakpoint(struct perf_event *bp); +void hw_breakpoint_pmu_read(struct perf_event *bp); +int hw_breakpoint_slots(int type); + +#endif /* __KERNEL__ */ +#endif /* _ARM_HW_BREAKPOINT_H */ diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c new file mode 100644 index 00000000000..54593b0c241 --- /dev/null +++ b/arch/arm/kernel/hw_breakpoint.c @@ -0,0 +1,849 @@ +/* + * 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 <will.deacon@arm.com> + */ + +/* + * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility, + * using the CPU's debug registers. + */ +#define pr_fmt(fmt) "hw-breakpoint: " fmt + +#include <linux/errno.h> +#include <linux/perf_event.h> +#include <linux/hw_breakpoint.h> +#include <linux/smp.h> + +#include <asm/cacheflush.h> +#include <asm/cputype.h> +#include <asm/current.h> +#include <asm/hw_breakpoint.h> +#include <asm/kdebug.h> +#include <asm/system.h> +#include <asm/traps.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]); + +/* Number of BRP/WRP registers on this CPU. */ +static int core_num_brps; +static int core_num_wrps; + +/* Debug architecture version. */ +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); \ + 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(); +} + +/* + * 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.")) { + ret = -EPERM; + goto out; + } + + /* Write to the corresponding DSCR. */ + switch (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 (WARN_ONCE(!(dscr & ARM_DSCR_MDBGEN), + "failed to enable monitor mode.")) { + ret = -EPERM; + } + +out: + return ret; +} + +/* + * 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; + + if (enable_monitor_mode()) + 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; +} + +/* + * Handler for reactivating a suspended watchpoint when the single + * step `mismatch' breakpoint is triggered. + */ +static void wp_single_step_handler(struct perf_event *bp, int unused, + struct perf_sample_data *data, + struct pt_regs *regs) +{ + perf_event_enable(counter_arch_bp(bp)->suspended_wp); + unregister_hw_breakpoint(bp); +} + +static int bp_is_single_step(struct perf_event *bp) +{ + return bp->overflow_handler == wp_single_step_handler; +} + +/* + * 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; + + /* Ensure that we are in monitor mode and halting mode is disabled. */ + ret = enable_monitor_mode(); + if (ret) + goto out; + + if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) { + /* Breakpoint */ + ctrl_base = ARM_BASE_BCR; + val_base = ARM_BASE_BVR; + slots = __get_cpu_var(bp_on_reg); + max_slots = core_num_brps - 1; + + if (bp_is_single_step(bp)) { + info->ctrl.mismatch = 1; + i = max_slots; + slots[i] = bp; + goto setup; + } + } else { + /* Watchpoint */ + ctrl_base = ARM_BASE_WCR; + val_base = ARM_BASE_WVR; + slots = __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")) { + ret = -EBUSY; + goto out; + } + +setup: + /* Setup the address register. */ + write_wb_reg(val_base + i, info->address); + + /* Setup the control register. */ + write_wb_reg(ctrl_base + i, encode_ctrl_reg(info->ctrl) | 0x1); + +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 = __get_cpu_var(bp_on_reg); + max_slots = core_num_brps - 1; + + if (bp_is_single_step(bp)) { + i = max_slots; + slots[i] = NULL; + goto reset; + } + } else { + /* Watchpoint */ + base = ARM_BASE_WCR; + slots = __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")) + return; + +reset: + /* 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; + } + + /* Address */ + info->address = bp->attr.bp_addr; + + /* Privilege */ + info->ctrl.privilege = ARM_BREAKPOINT_USER; + if (arch_check_bp_in_kernelspace(bp) && !bp_is_single_step(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 bytelen, max_len, 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; + if (info->address & alignment_mask) { + /* + * Try to fix the alignment. This may result in a length + * that is too large, so we must check for that. + */ + bytelen = get_hbp_len(info->ctrl.len); + max_len = info->ctrl.type == ARM_BREAKPOINT_EXECUTE ? 4 : + max_watchpoint_len; + + if (max_len >= 8) + offset = info->address & 0x7; + else + offset = info->address & 0x3; + + if (bytelen > (1 << ((max_len - (offset + 1)) >> 1))) { + ret = -EFBIG; + goto out; + } + + info->ctrl.len <<= offset; + info->address &= ~offset; + + pr_debug("breakpoint alignment fixup: length = 0x%x, " + "address = 0x%x\n", info->ctrl.len, info->address); + } + + /* + * 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. + */ + if (WARN_ONCE(!bp->overflow_handler && + (arch_check_bp_in_kernelspace(bp) || !core_has_mismatch_bps()), + "overflow handler required but none found")) { + ret = -EINVAL; + goto out; + } +out: + return ret; +} + +static void update_mismatch_flag(int idx, int flag) +{ + struct perf_event *bp = __get_cpu_var(bp_on_reg[idx]); + struct arch_hw_breakpoint *info; + + if (bp == NULL) + return; + + info = counter_arch_bp(bp); + + /* Update the mismatch field to enter/exit `single-step' mode */ + if (!bp->overflow_handler && info->ctrl.mismatch != flag) { + info->ctrl.mismatch = flag; + write_wb_reg(ARM_BASE_BCR + idx, encode_ctrl_reg(info->ctrl) | 0x1); + } +} + +static void watchpoint_handler(unsigned long unknown, struct pt_regs *regs) +{ + int i; + struct perf_event *bp, **slots = __get_cpu_var(wp_on_reg); + struct arch_hw_breakpoint *info; + struct perf_event_attr attr; + + /* Without a disassembler, we can only handle 1 watchpoint. */ + BUG_ON(core_num_wrps > 1); + + hw_breakpoint_init(&attr); + attr.bp_addr = regs->ARM_pc & ~0x3; + attr.bp_len = HW_BREAKPOINT_LEN_4; + attr.bp_type = HW_BREAKPOINT_X; + + for (i = 0; i < core_num_wrps; ++i) { + rcu_read_lock(); + + if (slots[i] == 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(slots[i]); + info->trigger = slots[i]->attr.bp_addr; + pr_debug("watchpoint fired: address = 0x%x\n", info->trigger); + perf_bp_event(slots[i], regs); + + /* + * If no overflow handler is present, insert a temporary + * mismatch breakpoint so we can single-step over the + * watchpoint trigger. + */ + if (!slots[i]->overflow_handler) { + bp = register_user_hw_breakpoint(&attr, + wp_single_step_handler, + current); + counter_arch_bp(bp)->suspended_wp = slots[i]; + perf_event_disable(slots[i]); + } + + rcu_read_unlock(); + } +} + +static void breakpoint_handler(unsigned long unknown, struct pt_regs *regs) +{ + int i; + int mismatch; + u32 ctrl_reg, val, addr; + struct perf_event *bp, **slots = __get_cpu_var(bp_on_reg); + struct arch_hw_breakpoint *info; + struct arch_hw_breakpoint_ctrl ctrl; + + /* The exception entry code places the amended lr in the PC. */ + addr = regs->ARM_pc; + + for (i = 0; i < core_num_brps; ++i) { + rcu_read_lock(); + + bp = slots[i]; + + if (bp == NULL) { + rcu_read_unlock(); + continue; + } + + mismatch = 0; + + /* Check if the breakpoint value matches. */ + val = read_wb_reg(ARM_BASE_BVR + i); + if (val != (addr & ~0x3)) + goto unlock; + + /* 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) { + mismatch = 1; + info = counter_arch_bp(bp); + info->trigger = addr; + } + +unlock: + if ((mismatch && !info->ctrl.mismatch) || bp_is_single_step(bp)) { + pr_debug("breakpoint fired: address = 0x%x\n", addr); + perf_bp_event(bp, regs); + } + + update_mismatch_flag(i, mismatch); + rcu_read_unlock(); + } +} + +/* + * Called from either the Data Abort Handler [watchpoint] or the + * Prefetch Abort Handler [breakpoint]. + */ +static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr, + struct pt_regs *regs) +{ + int ret = 1; /* Unhandled fault. */ + u32 dscr; + + /* 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_ON("Asynchronous watchpoint exception taken. " + "Debugging results may be unreliable"); + case ARM_ENTRY_SYNC_WATCHPOINT: + watchpoint_handler(addr, regs); + break; + default: + goto out; + } + + ret = 0; +out: + return ret; +} + +/* + * One-time initialisation. + */ +static void __init reset_ctrl_regs(void *unused) +{ + int i; + + if (enable_monitor_mode()) + return; + + for (i = 0; i < core_num_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 __init arch_hw_breakpoint_init(void) +{ + int ret = 0; + u32 dscr; + + debug_arch = get_debug_arch(); + + if (debug_arch > ARM_DEBUG_ARCH_V7_ECP14) { + pr_info("debug architecture 0x%x unsupported.\n", debug_arch); + ret = -ENODEV; + goto out; + } + + /* Determine how many BRPs/WRPs are available. */ + 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); + + if (core_has_mismatch_bps()) + pr_info("1 breakpoint reserved for watchpoint single-step.\n"); + + ARM_DBG_READ(c1, 0, dscr); + if (dscr & ARM_DSCR_HDBGEN) { + pr_warning("halting debug mode enabled. Assuming maximum " + "watchpoint size of 4 bytes."); + } 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); + + /* + * Reset the breakpoint resources. We assume that a halting + * debugger will leave the world in a nice state for us. + */ + smp_call_function(reset_ctrl_regs, NULL, 1); + reset_ctrl_regs(NULL); + } + + /* 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"); + +out: + return ret; +} +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; +} |