v4.19.13 snapshot.
diff --git a/arch/xtensa/kernel/hw_breakpoint.c b/arch/xtensa/kernel/hw_breakpoint.c
new file mode 100644
index 0000000..c2e387c
--- /dev/null
+++ b/arch/xtensa/kernel/hw_breakpoint.c
@@ -0,0 +1,307 @@
+/*
+ * Xtensa hardware breakpoints/watchpoints handling functions
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2016 Cadence Design Systems Inc.
+ */
+
+#include <linux/hw_breakpoint.h>
+#include <linux/log2.h>
+#include <linux/percpu.h>
+#include <linux/perf_event.h>
+#include <variant/core.h>
+
+/* Breakpoint currently in use for each IBREAKA. */
+static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[XCHAL_NUM_IBREAK]);
+
+/* Watchpoint currently in use for each DBREAKA. */
+static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[XCHAL_NUM_DBREAK]);
+
+int hw_breakpoint_slots(int type)
+{
+ switch (type) {
+ case TYPE_INST:
+ return XCHAL_NUM_IBREAK;
+ case TYPE_DATA:
+ return XCHAL_NUM_DBREAK;
+ default:
+ pr_warn("unknown slot type: %d\n", type);
+ return 0;
+ }
+}
+
+int arch_check_bp_in_kernelspace(struct arch_hw_breakpoint *hw)
+{
+ unsigned int len;
+ unsigned long va;
+
+ va = hw->address;
+ len = hw->len;
+
+ return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+}
+
+/*
+ * Construct an arch_hw_breakpoint from a perf_event.
+ */
+int hw_breakpoint_arch_parse(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->type = XTENSA_BREAKPOINT_EXECUTE;
+ break;
+ case HW_BREAKPOINT_R:
+ hw->type = XTENSA_BREAKPOINT_LOAD;
+ break;
+ case HW_BREAKPOINT_W:
+ hw->type = XTENSA_BREAKPOINT_STORE;
+ break;
+ case HW_BREAKPOINT_RW:
+ hw->type = XTENSA_BREAKPOINT_LOAD | XTENSA_BREAKPOINT_STORE;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* Len */
+ hw->len = attr->bp_len;
+ if (hw->len < 1 || hw->len > 64 || !is_power_of_2(hw->len))
+ return -EINVAL;
+
+ /* Address */
+ hw->address = attr->bp_addr;
+ if (hw->address & (hw->len - 1))
+ return -EINVAL;
+
+ return 0;
+}
+
+int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
+ unsigned long val, void *data)
+{
+ return NOTIFY_DONE;
+}
+
+static void xtensa_wsr(unsigned long v, u8 sr)
+{
+ /* We don't have indexed wsr and creating instruction dynamically
+ * doesn't seem worth it given how small XCHAL_NUM_IBREAK and
+ * XCHAL_NUM_DBREAK are. Thus the switch. In case build breaks here
+ * the switch below needs to be extended.
+ */
+ BUILD_BUG_ON(XCHAL_NUM_IBREAK > 2);
+ BUILD_BUG_ON(XCHAL_NUM_DBREAK > 2);
+
+ switch (sr) {
+#if XCHAL_NUM_IBREAK > 0
+ case SREG_IBREAKA + 0:
+ WSR(v, SREG_IBREAKA + 0);
+ break;
+#endif
+#if XCHAL_NUM_IBREAK > 1
+ case SREG_IBREAKA + 1:
+ WSR(v, SREG_IBREAKA + 1);
+ break;
+#endif
+
+#if XCHAL_NUM_DBREAK > 0
+ case SREG_DBREAKA + 0:
+ WSR(v, SREG_DBREAKA + 0);
+ break;
+ case SREG_DBREAKC + 0:
+ WSR(v, SREG_DBREAKC + 0);
+ break;
+#endif
+#if XCHAL_NUM_DBREAK > 1
+ case SREG_DBREAKA + 1:
+ WSR(v, SREG_DBREAKA + 1);
+ break;
+
+ case SREG_DBREAKC + 1:
+ WSR(v, SREG_DBREAKC + 1);
+ break;
+#endif
+ }
+}
+
+static int alloc_slot(struct perf_event **slot, size_t n,
+ struct perf_event *bp)
+{
+ size_t i;
+
+ for (i = 0; i < n; ++i) {
+ if (!slot[i]) {
+ slot[i] = bp;
+ return i;
+ }
+ }
+ return -EBUSY;
+}
+
+static void set_ibreak_regs(int reg, struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ unsigned long ibreakenable;
+
+ xtensa_wsr(info->address, SREG_IBREAKA + reg);
+ RSR(ibreakenable, SREG_IBREAKENABLE);
+ WSR(ibreakenable | (1 << reg), SREG_IBREAKENABLE);
+}
+
+static void set_dbreak_regs(int reg, struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ unsigned long dbreakc = DBREAKC_MASK_MASK & -info->len;
+
+ if (info->type & XTENSA_BREAKPOINT_LOAD)
+ dbreakc |= DBREAKC_LOAD_MASK;
+ if (info->type & XTENSA_BREAKPOINT_STORE)
+ dbreakc |= DBREAKC_STOR_MASK;
+
+ xtensa_wsr(info->address, SREG_DBREAKA + reg);
+ xtensa_wsr(dbreakc, SREG_DBREAKC + reg);
+}
+
+int arch_install_hw_breakpoint(struct perf_event *bp)
+{
+ int i;
+
+ if (counter_arch_bp(bp)->type == XTENSA_BREAKPOINT_EXECUTE) {
+ /* Breakpoint */
+ i = alloc_slot(this_cpu_ptr(bp_on_reg), XCHAL_NUM_IBREAK, bp);
+ if (i < 0)
+ return i;
+ set_ibreak_regs(i, bp);
+
+ } else {
+ /* Watchpoint */
+ i = alloc_slot(this_cpu_ptr(wp_on_reg), XCHAL_NUM_DBREAK, bp);
+ if (i < 0)
+ return i;
+ set_dbreak_regs(i, bp);
+ }
+ return 0;
+}
+
+static int free_slot(struct perf_event **slot, size_t n,
+ struct perf_event *bp)
+{
+ size_t i;
+
+ for (i = 0; i < n; ++i) {
+ if (slot[i] == bp) {
+ slot[i] = NULL;
+ return i;
+ }
+ }
+ return -EBUSY;
+}
+
+void arch_uninstall_hw_breakpoint(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ int i;
+
+ if (info->type == XTENSA_BREAKPOINT_EXECUTE) {
+ unsigned long ibreakenable;
+
+ /* Breakpoint */
+ i = free_slot(this_cpu_ptr(bp_on_reg), XCHAL_NUM_IBREAK, bp);
+ if (i >= 0) {
+ RSR(ibreakenable, SREG_IBREAKENABLE);
+ WSR(ibreakenable & ~(1 << i), SREG_IBREAKENABLE);
+ }
+ } else {
+ /* Watchpoint */
+ i = free_slot(this_cpu_ptr(wp_on_reg), XCHAL_NUM_DBREAK, bp);
+ if (i >= 0)
+ xtensa_wsr(0, SREG_DBREAKC + i);
+ }
+}
+
+void hw_breakpoint_pmu_read(struct perf_event *bp)
+{
+}
+
+void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
+{
+ int i;
+ struct thread_struct *t = &tsk->thread;
+
+ for (i = 0; i < XCHAL_NUM_IBREAK; ++i) {
+ if (t->ptrace_bp[i]) {
+ unregister_hw_breakpoint(t->ptrace_bp[i]);
+ t->ptrace_bp[i] = NULL;
+ }
+ }
+ for (i = 0; i < XCHAL_NUM_DBREAK; ++i) {
+ if (t->ptrace_wp[i]) {
+ unregister_hw_breakpoint(t->ptrace_wp[i]);
+ t->ptrace_wp[i] = NULL;
+ }
+ }
+}
+
+/*
+ * Set ptrace breakpoint pointers to zero for this task.
+ * This is required in order to prevent child processes from unregistering
+ * breakpoints held by their parent.
+ */
+void clear_ptrace_hw_breakpoint(struct task_struct *tsk)
+{
+ memset(tsk->thread.ptrace_bp, 0, sizeof(tsk->thread.ptrace_bp));
+ memset(tsk->thread.ptrace_wp, 0, sizeof(tsk->thread.ptrace_wp));
+}
+
+void restore_dbreak(void)
+{
+ int i;
+
+ for (i = 0; i < XCHAL_NUM_DBREAK; ++i) {
+ struct perf_event *bp = this_cpu_ptr(wp_on_reg)[i];
+
+ if (bp)
+ set_dbreak_regs(i, bp);
+ }
+ clear_thread_flag(TIF_DB_DISABLED);
+}
+
+int check_hw_breakpoint(struct pt_regs *regs)
+{
+ if (regs->debugcause & BIT(DEBUGCAUSE_IBREAK_BIT)) {
+ int i;
+ struct perf_event **bp = this_cpu_ptr(bp_on_reg);
+
+ for (i = 0; i < XCHAL_NUM_IBREAK; ++i) {
+ if (bp[i] && !bp[i]->attr.disabled &&
+ regs->pc == bp[i]->attr.bp_addr)
+ perf_bp_event(bp[i], regs);
+ }
+ return 0;
+ } else if (regs->debugcause & BIT(DEBUGCAUSE_DBREAK_BIT)) {
+ struct perf_event **bp = this_cpu_ptr(wp_on_reg);
+ int dbnum = (regs->debugcause & DEBUGCAUSE_DBNUM_MASK) >>
+ DEBUGCAUSE_DBNUM_SHIFT;
+
+ if (dbnum < XCHAL_NUM_DBREAK && bp[dbnum]) {
+ if (user_mode(regs)) {
+ perf_bp_event(bp[dbnum], regs);
+ } else {
+ set_thread_flag(TIF_DB_DISABLED);
+ xtensa_wsr(0, SREG_DBREAKC + dbnum);
+ }
+ } else {
+ WARN_ONCE(1,
+ "Wrong/unconfigured DBNUM reported in DEBUGCAUSE: %d\n",
+ dbnum);
+ }
+ return 0;
+ }
+ return -ENOENT;
+}