--- /dev/null
+/*
+ * 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;
+}
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff