1 files changed, 176 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/stacktrace/common.h b/arch/arm64/include/asm/stacktrace/common.h
new file mode 100644
index 000000000..508f734de
--- /dev/null
+++ b/arch/arm64/include/asm/stacktrace/common.h
@@ -0,0 +1,176 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Common arm64 stack unwinder code.
+ *
+ * See: arch/arm64/kernel/stacktrace.c for the reference implementation.
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ */
+#ifndef __ASM_STACKTRACE_COMMON_H
+#define __ASM_STACKTRACE_COMMON_H
+
+#include <linux/kprobes.h>
+#include <linux/types.h>
+
+struct stack_info {
+	unsigned long low;
+	unsigned long high;
+};
+
+/**
+ * struct unwind_state - state used for robust unwinding.
+ *
+ * @fp:          The fp value in the frame record (or the real fp)
+ * @pc:          The lr value in the frame record (or the real lr)
+ *
+ * @kr_cur:      When KRETPROBES is selected, holds the kretprobe instance
+ *               associated with the most recently encountered replacement lr
+ *               value.
+ *
+ * @task:        The task being unwound.
+ *
+ * @stack:       The stack currently being unwound.
+ * @stacks:      An array of stacks which can be unwound.
+ * @nr_stacks:   The number of stacks in @stacks.
+ */
+struct unwind_state {
+	unsigned long fp;
+	unsigned long pc;
+#ifdef CONFIG_KRETPROBES
+	struct llist_node *kr_cur;
+#endif
+	struct task_struct *task;
+
+	struct stack_info stack;
+	struct stack_info *stacks;
+	int nr_stacks;
+};
+
+static inline struct stack_info stackinfo_get_unknown(void)
+{
+	return (struct stack_info) {
+		.low = 0,
+		.high = 0,
+	};
+}
+
+static inline bool stackinfo_on_stack(const struct stack_info *info,
+				      unsigned long sp, unsigned long size)
+{
+	if (!info->low)
+		return false;
+
+	if (sp < info->low || sp + size < sp || sp + size > info->high)
+		return false;
+
+	return true;
+}
+
+static inline void unwind_init_common(struct unwind_state *state,
+				      struct task_struct *task)
+{
+	state->task = task;
+#ifdef CONFIG_KRETPROBES
+	state->kr_cur = NULL;
+#endif
+
+	state->stack = stackinfo_get_unknown();
+}
+
+static struct stack_info *unwind_find_next_stack(const struct unwind_state *state,
+						 unsigned long sp,
+						 unsigned long size)
+{
+	for (int i = 0; i < state->nr_stacks; i++) {
+		struct stack_info *info = &state->stacks[i];
+
+		if (stackinfo_on_stack(info, sp, size))
+			return info;
+	}
+
+	return NULL;
+}
+
+/**
+ * unwind_consume_stack() - Check if an object is on an accessible stack,
+ * updating stack boundaries so that future unwind steps cannot consume this
+ * object again.
+ *
+ * @state: the current unwind state.
+ * @sp:    the base address of the object.
+ * @size:  the size of the object.
+ *
+ * Return: 0 upon success, an error code otherwise.
+ */
+static inline int unwind_consume_stack(struct unwind_state *state,
+				       unsigned long sp,
+				       unsigned long size)
+{
+	struct stack_info *next;
+
+	if (stackinfo_on_stack(&state->stack, sp, size))
+		goto found;
+
+	next = unwind_find_next_stack(state, sp, size);
+	if (!next)
+		return -EINVAL;
+
+	/*
+	 * Stack transitions are strictly one-way, and once we've
+	 * transitioned from one stack to another, it's never valid to
+	 * unwind back to the old stack.
+	 *
+	 * Remove the current stack from the list of stacks so that it cannot
+	 * be found on a subsequent transition.
+	 *
+	 * Note that stacks can nest in several valid orders, e.g.
+	 *
+	 *   TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL
+	 *   TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW
+	 *   HYP -> OVERFLOW
+	 *
+	 * ... so we do not check the specific order of stack
+	 * transitions.
+	 */
+	state->stack = *next;
+	*next = stackinfo_get_unknown();
+
+found:
+	/*
+	 * Future unwind steps can only consume stack above this frame record.
+	 * Update the current stack to start immediately above it.
+	 */
+	state->stack.low = sp + size;
+	return 0;
+}
+
+/**
+ * unwind_next_frame_record() - Unwind to the next frame record.
+ *
+ * @state:        the current unwind state.
+ *
+ * Return: 0 upon success, an error code otherwise.
+ */
+static inline int
+unwind_next_frame_record(struct unwind_state *state)
+{
+	unsigned long fp = state->fp;
+	int err;
+
+	if (fp & 0x7)
+		return -EINVAL;
+
+	err = unwind_consume_stack(state, fp, 16);
+	if (err)
+		return err;
+
+	/*
+	 * Record this frame record's values.
+	 */
+	state->fp = READ_ONCE(*(unsigned long *)(fp));
+	state->pc = READ_ONCE(*(unsigned long *)(fp + 8));
+
+	return 0;
+}
+
+#endif	/* __ASM_STACKTRACE_COMMON_H */