v4.19.13 snapshot.
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
new file mode 100644
index 0000000..1d5fbf1
--- /dev/null
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -0,0 +1,1147 @@
+/*
+ * 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/hardirq.h>
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/smp.h>
+#include <linux/cpu_pm.h>
+#include <linux/coresight.h>
+
+#include <asm/cacheflush.h>
+#include <asm/cputype.h>
+#include <asm/current.h>
+#include <asm/hw_breakpoint.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 __ro_after_init;
+static int core_num_wrps __ro_after_init;
+
+/* Debug architecture version. */
+static u8 debug_arch __ro_after_init;
+
+/* Does debug architecture support OS Save and Restore? */
+static bool has_ossr __ro_after_init;
+
+/* Maximum supported watchpoint length. */
+static u8 max_watchpoint_len __ro_after_init;
+
+#define READ_WB_REG_CASE(OP2, M, VAL) \
+ case ((OP2 << 4) + M): \
+ ARM_DBG_READ(c0, c ## M, OP2, VAL); \
+ break
+
+#define WRITE_WB_REG_CASE(OP2, M, VAL) \
+ case ((OP2 << 4) + M): \
+ ARM_DBG_WRITE(c0, 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_warn("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_warn("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 (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
+ pr_warn_once("CPUID feature registers not supported. "
+ "Assuming v6 debug is present.\n");
+ return ARM_DEBUG_ARCH_V6;
+ }
+
+ ARM_DBG_READ(c0, 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();
+
+ /* We don't support the memory-mapped interface. */
+ return (arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14) ||
+ arch >= ARM_DEBUG_ARCH_V7_1;
+}
+
+/* Can we determine the watchpoint access type from the fsr? */
+static int debug_exception_updates_fsr(void)
+{
+ return get_debug_arch() >= ARM_DEBUG_ARCH_V8;
+}
+
+/* Determine number of WRP registers available. */
+static int get_num_wrp_resources(void)
+{
+ u32 didr;
+ ARM_DBG_READ(c0, c0, 0, didr);
+ return ((didr >> 28) & 0xf) + 1;
+}
+
+/* Determine number of BRP registers available. */
+static int get_num_brp_resources(void)
+{
+ u32 didr;
+ ARM_DBG_READ(c0, 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)
+{
+ /*
+ * On debug architectures prior to 7.1, 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 (get_debug_arch() < ARM_DEBUG_ARCH_V7_1)
+ return 1;
+
+ return get_num_wrp_resources();
+}
+
+/* Determine number of usable BRPs available. */
+static int get_num_brps(void)
+{
+ int brps = get_num_brp_resources();
+ return core_has_mismatch_brps() ? brps - 1 : 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 monitor_mode_enabled(void)
+{
+ u32 dscr;
+ ARM_DBG_READ(c0, c1, 0, dscr);
+ return !!(dscr & ARM_DSCR_MDBGEN);
+}
+
+static int enable_monitor_mode(void)
+{
+ u32 dscr;
+ ARM_DBG_READ(c0, c1, 0, dscr);
+
+ /* 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(c0, c1, 0, (dscr | ARM_DSCR_MDBGEN));
+ break;
+ case ARM_DEBUG_ARCH_V7_ECP14:
+ case ARM_DEBUG_ARCH_V7_1:
+ case ARM_DEBUG_ARCH_V8:
+ ARM_DBG_WRITE(c0, c2, 2, (dscr | ARM_DSCR_MDBGEN));
+ isb();
+ break;
+ default:
+ return -ENODEV;
+ }
+
+ /* Check that the write made it through. */
+ ARM_DBG_READ(c0, c1, 0, dscr);
+ if (!(dscr & ARM_DSCR_MDBGEN)) {
+ pr_warn_once("Failed to enable monitor mode on CPU %d.\n",
+ smp_processor_id());
+ return -EPERM;
+ }
+
+out:
+ return 0;
+}
+
+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_warn("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;
+ u32 addr, ctrl;
+
+ 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 = this_cpu_ptr(bp_on_reg);
+ max_slots = core_num_brps;
+ } else {
+ /* Watchpoint */
+ ctrl_base = ARM_BASE_WCR;
+ val_base = ARM_BASE_WVR;
+ slots = this_cpu_ptr(wp_on_reg);
+ max_slots = core_num_wrps;
+ }
+
+ for (i = 0; i < max_slots; ++i) {
+ slot = &slots[i];
+
+ if (!*slot) {
+ *slot = bp;
+ break;
+ }
+ }
+
+ if (i == max_slots) {
+ pr_warn("Can't find any breakpoint slot\n");
+ return -EBUSY;
+ }
+
+ /* Override the breakpoint data with the step data. */
+ if (info->step_ctrl.enabled) {
+ addr = info->trigger & ~0x3;
+ ctrl = encode_ctrl_reg(info->step_ctrl);
+ if (info->ctrl.type != ARM_BREAKPOINT_EXECUTE) {
+ i = 0;
+ ctrl_base = ARM_BASE_BCR + core_num_brps;
+ val_base = ARM_BASE_BVR + core_num_brps;
+ }
+ }
+
+ /* Setup the address register. */
+ write_wb_reg(val_base + i, addr);
+
+ /* Setup the control register. */
+ write_wb_reg(ctrl_base + i, ctrl);
+ return 0;
+}
+
+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 = this_cpu_ptr(bp_on_reg);
+ max_slots = core_num_brps;
+ } else {
+ /* Watchpoint */
+ base = ARM_BASE_WCR;
+ slots = this_cpu_ptr(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 (i == max_slots) {
+ pr_warn("Can't find any breakpoint slot\n");
+ return;
+ }
+
+ /* Ensure that we disable the mismatch breakpoint. */
+ if (info->ctrl.type != ARM_BREAKPOINT_EXECUTE &&
+ info->step_ctrl.enabled) {
+ i = 0;
+ base = ARM_BASE_BCR + core_num_brps;
+ }
+
+ /* 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 arch_hw_breakpoint *hw)
+{
+ unsigned int len;
+ unsigned long va;
+
+ va = hw->address;
+ len = get_hbp_len(hw->ctrl.len);
+
+ return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+}
+
+/*
+ * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
+ * Hopefully this will disappear when ptrace can bypass the conversion
+ * to generic breakpoint descriptions.
+ */
+int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
+ int *gen_len, int *gen_type)
+{
+ /* 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,
+ const struct perf_event_attr *attr,
+ struct arch_hw_breakpoint *hw)
+{
+ /* Type */
+ switch (attr->bp_type) {
+ case HW_BREAKPOINT_X:
+ hw->ctrl.type = ARM_BREAKPOINT_EXECUTE;
+ break;
+ case HW_BREAKPOINT_R:
+ hw->ctrl.type = ARM_BREAKPOINT_LOAD;
+ break;
+ case HW_BREAKPOINT_W:
+ hw->ctrl.type = ARM_BREAKPOINT_STORE;
+ break;
+ case HW_BREAKPOINT_RW:
+ hw->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* Len */
+ switch (attr->bp_len) {
+ case HW_BREAKPOINT_LEN_1:
+ hw->ctrl.len = ARM_BREAKPOINT_LEN_1;
+ break;
+ case HW_BREAKPOINT_LEN_2:
+ hw->ctrl.len = ARM_BREAKPOINT_LEN_2;
+ break;
+ case HW_BREAKPOINT_LEN_4:
+ hw->ctrl.len = ARM_BREAKPOINT_LEN_4;
+ break;
+ case HW_BREAKPOINT_LEN_8:
+ hw->ctrl.len = ARM_BREAKPOINT_LEN_8;
+ if ((hw->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 (hw->ctrl.type == ARM_BREAKPOINT_EXECUTE &&
+ hw->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
+ hw->ctrl.len != ARM_BREAKPOINT_LEN_4)
+ return -EINVAL;
+
+ /* Address */
+ hw->address = attr->bp_addr;
+
+ /* Privilege */
+ hw->ctrl.privilege = ARM_BREAKPOINT_USER;
+ if (arch_check_bp_in_kernelspace(hw))
+ hw->ctrl.privilege |= ARM_BREAKPOINT_PRIV;
+
+ /* Enabled? */
+ hw->ctrl.enabled = !attr->disabled;
+
+ /* Mismatch */
+ hw->ctrl.mismatch = 0;
+
+ return 0;
+}
+
+/*
+ * Validate the arch-specific HW Breakpoint register settings.
+ */
+int hw_breakpoint_arch_parse(struct perf_event *bp,
+ const struct perf_event_attr *attr,
+ struct arch_hw_breakpoint *hw)
+{
+ int ret = 0;
+ u32 offset, alignment_mask = 0x3;
+
+ /* Ensure that we are in monitor debug mode. */
+ if (!monitor_mode_enabled())
+ return -ENODEV;
+
+ /* Build the arch_hw_breakpoint. */
+ ret = arch_build_bp_info(bp, attr, hw);
+ if (ret)
+ goto out;
+
+ /* Check address alignment. */
+ if (hw->ctrl.len == ARM_BREAKPOINT_LEN_8)
+ alignment_mask = 0x7;
+ offset = hw->address & alignment_mask;
+ switch (offset) {
+ case 0:
+ /* Aligned */
+ break;
+ case 1:
+ case 2:
+ /* Allow halfword watchpoints and breakpoints. */
+ if (hw->ctrl.len == ARM_BREAKPOINT_LEN_2)
+ break;
+ case 3:
+ /* Allow single byte watchpoint. */
+ if (hw->ctrl.len == ARM_BREAKPOINT_LEN_1)
+ break;
+ default:
+ ret = -EINVAL;
+ goto out;
+ }
+
+ hw->address &= ~alignment_mask;
+ hw->ctrl.len <<= offset;
+
+ if (is_default_overflow_handler(bp)) {
+ /*
+ * Mismatch breakpoints are required for single-stepping
+ * breakpoints.
+ */
+ if (!core_has_mismatch_brps())
+ return -EINVAL;
+
+ /* We don't allow mismatch breakpoints in kernel space. */
+ if (arch_check_bp_in_kernelspace(hw))
+ return -EPERM;
+
+ /*
+ * Per-cpu breakpoints are not supported by our stepping
+ * mechanism.
+ */
+ if (!bp->hw.target)
+ return -EINVAL;
+
+ /*
+ * We only support specific access types if the fsr
+ * reports them.
+ */
+ if (!debug_exception_updates_fsr() &&
+ (hw->ctrl.type == ARM_BREAKPOINT_LOAD ||
+ hw->ctrl.type == ARM_BREAKPOINT_STORE))
+ return -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 addr, unsigned int fsr,
+ struct pt_regs *regs)
+{
+ int i, access;
+ u32 val, ctrl_reg, alignment_mask;
+ struct perf_event *wp, **slots;
+ struct arch_hw_breakpoint *info;
+ struct arch_hw_breakpoint_ctrl ctrl;
+
+ slots = this_cpu_ptr(wp_on_reg);
+
+ for (i = 0; i < core_num_wrps; ++i) {
+ rcu_read_lock();
+
+ wp = slots[i];
+
+ if (wp == NULL)
+ goto unlock;
+
+ info = counter_arch_bp(wp);
+ /*
+ * The DFAR is an unknown value on debug architectures prior
+ * to 7.1. Since we only allow a single watchpoint on these
+ * older CPUs, we can set the trigger to the lowest possible
+ * faulting address.
+ */
+ if (debug_arch < ARM_DEBUG_ARCH_V7_1) {
+ BUG_ON(i > 0);
+ info->trigger = wp->attr.bp_addr;
+ } else {
+ if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
+ alignment_mask = 0x7;
+ else
+ alignment_mask = 0x3;
+
+ /* Check if the watchpoint value matches. */
+ val = read_wb_reg(ARM_BASE_WVR + i);
+ if (val != (addr & ~alignment_mask))
+ goto unlock;
+
+ /* Possible match, check the byte address select. */
+ ctrl_reg = read_wb_reg(ARM_BASE_WCR + i);
+ decode_ctrl_reg(ctrl_reg, &ctrl);
+ if (!((1 << (addr & alignment_mask)) & ctrl.len))
+ goto unlock;
+
+ /* Check that the access type matches. */
+ if (debug_exception_updates_fsr()) {
+ access = (fsr & ARM_FSR_ACCESS_MASK) ?
+ HW_BREAKPOINT_W : HW_BREAKPOINT_R;
+ if (!(access & hw_breakpoint_type(wp)))
+ goto unlock;
+ }
+
+ /* We have a winner. */
+ info->trigger = 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 (is_default_overflow_handler(wp))
+ enable_single_step(wp, instruction_pointer(regs));
+
+unlock:
+ 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 = this_cpu_ptr(wp_on_reg);
+
+ for (i = 0; i < core_num_wrps; ++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 = this_cpu_ptr(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 interrupts disabled.
+ */
+static int hw_breakpoint_pending(unsigned long addr, unsigned int fsr,
+ struct pt_regs *regs)
+{
+ int ret = 0;
+ u32 dscr;
+
+ preempt_disable();
+
+ if (interrupts_enabled(regs))
+ local_irq_enable();
+
+ /* We only handle watchpoints and hardware breakpoints. */
+ ARM_DBG_READ(c0, 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, fsr, regs);
+ break;
+ default:
+ ret = 1; /* Unhandled fault. */
+ }
+
+ preempt_enable();
+
+ return ret;
+}
+
+/*
+ * One-time initialisation.
+ */
+static cpumask_t debug_err_mask;
+
+static int debug_reg_trap(struct pt_regs *regs, unsigned int instr)
+{
+ int cpu = smp_processor_id();
+
+ pr_warn("Debug register access (0x%x) caused undefined instruction on CPU %d\n",
+ instr, cpu);
+
+ /* Set the error flag for this CPU and skip the faulting instruction. */
+ cpumask_set_cpu(cpu, &debug_err_mask);
+ instruction_pointer(regs) += 4;
+ return 0;
+}
+
+static struct undef_hook debug_reg_hook = {
+ .instr_mask = 0x0fe80f10,
+ .instr_val = 0x0e000e10,
+ .fn = debug_reg_trap,
+};
+
+/* Does this core support OS Save and Restore? */
+static bool core_has_os_save_restore(void)
+{
+ u32 oslsr;
+
+ switch (get_debug_arch()) {
+ case ARM_DEBUG_ARCH_V7_1:
+ return true;
+ case ARM_DEBUG_ARCH_V7_ECP14:
+ ARM_DBG_READ(c1, c1, 4, oslsr);
+ if (oslsr & ARM_OSLSR_OSLM0)
+ return true;
+ default:
+ return false;
+ }
+}
+
+static void reset_ctrl_regs(unsigned int cpu)
+{
+ int i, raw_num_brps, err = 0;
+ u32 val;
+
+ /*
+ * 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.
+ */
+ switch (debug_arch) {
+ case ARM_DEBUG_ARCH_V6:
+ case ARM_DEBUG_ARCH_V6_1:
+ /* ARMv6 cores clear the registers out of reset. */
+ goto out_mdbgen;
+ case ARM_DEBUG_ARCH_V7_ECP14:
+ /*
+ * Ensure sticky power-down is clear (i.e. debug logic is
+ * powered up).
+ */
+ ARM_DBG_READ(c1, c5, 4, val);
+ if ((val & 0x1) == 0)
+ err = -EPERM;
+
+ if (!has_ossr)
+ goto clear_vcr;
+ break;
+ case ARM_DEBUG_ARCH_V7_1:
+ /*
+ * Ensure the OS double lock is clear.
+ */
+ ARM_DBG_READ(c1, c3, 4, val);
+ if ((val & 0x1) == 1)
+ err = -EPERM;
+ break;
+ }
+
+ if (err) {
+ pr_warn_once("CPU %d debug is powered down!\n", cpu);
+ cpumask_or(&debug_err_mask, &debug_err_mask, cpumask_of(cpu));
+ return;
+ }
+
+ /*
+ * Unconditionally clear the OS lock by writing a value
+ * other than CS_LAR_KEY to the access register.
+ */
+ ARM_DBG_WRITE(c1, c0, 4, ~CORESIGHT_UNLOCK);
+ isb();
+
+ /*
+ * Clear any configured vector-catch events before
+ * enabling monitor mode.
+ */
+clear_vcr:
+ ARM_DBG_WRITE(c0, c7, 0, 0);
+ isb();
+
+ if (cpumask_intersects(&debug_err_mask, cpumask_of(cpu))) {
+ pr_warn_once("CPU %d failed to disable vector catch\n", cpu);
+ return;
+ }
+
+ /*
+ * The control/value register pairs are UNKNOWN out of reset so
+ * clear them to avoid spurious debug events.
+ */
+ raw_num_brps = get_num_brp_resources();
+ for (i = 0; i < raw_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);
+ }
+
+ if (cpumask_intersects(&debug_err_mask, cpumask_of(cpu))) {
+ pr_warn_once("CPU %d failed to clear debug register pairs\n", cpu);
+ return;
+ }
+
+ /*
+ * Have a crack at enabling monitor mode. We don't actually need
+ * it yet, but reporting an error early is useful if it fails.
+ */
+out_mdbgen:
+ if (enable_monitor_mode())
+ cpumask_or(&debug_err_mask, &debug_err_mask, cpumask_of(cpu));
+}
+
+static int dbg_reset_online(unsigned int cpu)
+{
+ local_irq_disable();
+ reset_ctrl_regs(cpu);
+ local_irq_enable();
+ return 0;
+}
+
+#ifdef CONFIG_CPU_PM
+static int dbg_cpu_pm_notify(struct notifier_block *self, unsigned long action,
+ void *v)
+{
+ if (action == CPU_PM_EXIT)
+ reset_ctrl_regs(smp_processor_id());
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block dbg_cpu_pm_nb = {
+ .notifier_call = dbg_cpu_pm_notify,
+};
+
+static void __init pm_init(void)
+{
+ cpu_pm_register_notifier(&dbg_cpu_pm_nb);
+}
+#else
+static inline void pm_init(void)
+{
+}
+#endif
+
+static int __init arch_hw_breakpoint_init(void)
+{
+ int ret;
+
+ debug_arch = get_debug_arch();
+
+ if (!debug_arch_supported()) {
+ pr_info("debug architecture 0x%x unsupported.\n", debug_arch);
+ return 0;
+ }
+
+ /*
+ * Scorpion CPUs (at least those in APQ8060) seem to set DBGPRSR.SPD
+ * whenever a WFI is issued, even if the core is not powered down, in
+ * violation of the architecture. When DBGPRSR.SPD is set, accesses to
+ * breakpoint and watchpoint registers are treated as undefined, so
+ * this results in boot time and runtime failures when these are
+ * accessed and we unexpectedly take a trap.
+ *
+ * It's not clear if/how this can be worked around, so we blacklist
+ * Scorpion CPUs to avoid these issues.
+ */
+ if (read_cpuid_part() == ARM_CPU_PART_SCORPION) {
+ pr_info("Scorpion CPU detected. Hardware breakpoints and watchpoints disabled\n");
+ return 0;
+ }
+
+ has_ossr = core_has_os_save_restore();
+
+ /* Determine how many BRPs/WRPs are available. */
+ core_num_brps = get_num_brps();
+ core_num_wrps = get_num_wrps();
+
+ /*
+ * We need to tread carefully here because DBGSWENABLE may be
+ * driven low on this core and there isn't an architected way to
+ * determine that.
+ */
+ cpus_read_lock();
+ register_undef_hook(&debug_reg_hook);
+
+ /*
+ * Register CPU notifier which resets the breakpoint resources. We
+ * assume that a halting debugger will leave the world in a nice state
+ * for us.
+ */
+ ret = cpuhp_setup_state_cpuslocked(CPUHP_AP_ONLINE_DYN,
+ "arm/hw_breakpoint:online",
+ dbg_reset_online, NULL);
+ unregister_undef_hook(&debug_reg_hook);
+ if (WARN_ON(ret < 0) || !cpumask_empty(&debug_err_mask)) {
+ core_num_brps = 0;
+ core_num_wrps = 0;
+ if (ret > 0)
+ cpuhp_remove_state_nocalls_cpuslocked(ret);
+ cpus_read_unlock();
+ return 0;
+ }
+
+ pr_info("found %d " "%s" "breakpoint and %d watchpoint registers.\n",
+ core_num_brps, core_has_mismatch_brps() ? "(+1 reserved) " :
+ "", core_num_wrps);
+
+ /* 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(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,
+ TRAP_HWBKPT, "watchpoint debug exception");
+ hook_ifault_code(FAULT_CODE_DEBUG, hw_breakpoint_pending, SIGTRAP,
+ TRAP_HWBKPT, "breakpoint debug exception");
+ cpus_read_unlock();
+
+ /* Register PM notifiers. */
+ pm_init();
+ 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;
+}