1 files changed, 226 insertions, 0 deletions
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
new file mode 100644
index 000000000000..b41b6255751c
--- /dev/null
+++ b/arch/riscv/kernel/stacktrace.c
@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2008 ARM Limited
+ * Copyright (C) 2014 Regents of the University of California
+ */
+
+#include <linux/export.h>
+#include <linux/kallsyms.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/stacktrace.h>
+#include <linux/ftrace.h>
+
+#include <asm/stacktrace.h>
+
+#ifdef CONFIG_FRAME_POINTER
+
+/*
+ * This disables KASAN checking when reading a value from another task's stack,
+ * since the other task could be running on another CPU and could have poisoned
+ * the stack in the meantime.
+ */
+#define READ_ONCE_TASK_STACK(task, x)			\
+({							\
+	unsigned long val;				\
+	unsigned long addr = x;				\
+	if ((task) == current)				\
+		val = READ_ONCE(addr);			\
+	else						\
+		val = READ_ONCE_NOCHECK(addr);		\
+	val;						\
+})
+
+extern asmlinkage void handle_exception(void);
+extern unsigned long ret_from_exception_end;
+
+static inline int fp_is_valid(unsigned long fp, unsigned long sp)
+{
+	unsigned long low, high;
+
+	low = sp + sizeof(struct stackframe);
+	high = ALIGN(sp, THREAD_SIZE);
+
+	return !(fp < low || fp > high || fp & 0x07);
+}
+
+void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
+			     bool (*fn)(void *, unsigned long), void *arg)
+{
+	unsigned long fp, sp, pc;
+	int graph_idx = 0;
+	int level = 0;
+
+	if (regs) {
+		fp = frame_pointer(regs);
+		sp = user_stack_pointer(regs);
+		pc = instruction_pointer(regs);
+	} else if (task == NULL || task == current) {
+		fp = (unsigned long)__builtin_frame_address(0);
+		sp = current_stack_pointer;
+		pc = (unsigned long)walk_stackframe;
+		level = -1;
+	} else {
+		/* task blocked in __switch_to */
+		fp = task->thread.s[0];
+		sp = task->thread.sp;
+		pc = task->thread.ra;
+	}
+
+	for (;;) {
+		struct stackframe *frame;
+
+		if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
+			break;
+
+		if (unlikely(!fp_is_valid(fp, sp)))
+			break;
+
+		/* Unwind stack frame */
+		frame = (struct stackframe *)fp - 1;
+		sp = fp;
+		if (regs && (regs->epc == pc) && fp_is_valid(frame->ra, sp)) {
+			/* We hit function where ra is not saved on the stack */
+			fp = frame->ra;
+			pc = regs->ra;
+		} else {
+			fp = READ_ONCE_TASK_STACK(task, frame->fp);
+			pc = READ_ONCE_TASK_STACK(task, frame->ra);
+			pc = ftrace_graph_ret_addr(current, &graph_idx, pc,
+						   &frame->ra);
+			if (pc >= (unsigned long)handle_exception &&
+			    pc < (unsigned long)&ret_from_exception_end) {
+				if (unlikely(!fn(arg, pc)))
+					break;
+
+				pc = ((struct pt_regs *)sp)->epc;
+				fp = ((struct pt_regs *)sp)->s0;
+			}
+		}
+
+	}
+}
+
+#else /* !CONFIG_FRAME_POINTER */
+
+void notrace walk_stackframe(struct task_struct *task,
+	struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
+{
+	unsigned long sp, pc;
+	unsigned long *ksp;
+
+	if (regs) {
+		sp = user_stack_pointer(regs);
+		pc = instruction_pointer(regs);
+	} else if (task == NULL || task == current) {
+		sp = current_stack_pointer;
+		pc = (unsigned long)walk_stackframe;
+	} else {
+		/* task blocked in __switch_to */
+		sp = task->thread.sp;
+		pc = task->thread.ra;
+	}
+
+	if (unlikely(sp & 0x7))
+		return;
+
+	ksp = (unsigned long *)sp;
+	while (!kstack_end(ksp)) {
+		if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
+			break;
+		pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
+	}
+}
+
+#endif /* CONFIG_FRAME_POINTER */
+
+static bool print_trace_address(void *arg, unsigned long pc)
+{
+	const char *loglvl = arg;
+
+	print_ip_sym(loglvl, pc);
+	return true;
+}
+
+noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
+		    const char *loglvl)
+{
+	walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
+}
+
+void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
+{
+	pr_cont("%sCall Trace:\n", loglvl);
+	dump_backtrace(NULL, task, loglvl);
+}
+
+static bool save_wchan(void *arg, unsigned long pc)
+{
+	if (!in_sched_functions(pc)) {
+		unsigned long *p = arg;
+		*p = pc;
+		return false;
+	}
+	return true;
+}
+
+unsigned long __get_wchan(struct task_struct *task)
+{
+	unsigned long pc = 0;
+
+	if (!try_get_task_stack(task))
+		return 0;
+	walk_stackframe(task, NULL, save_wchan, &pc);
+	put_task_stack(task);
+	return pc;
+}
+
+noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+		     struct task_struct *task, struct pt_regs *regs)
+{
+	walk_stackframe(task, regs, consume_entry, cookie);
+}
+
+/*
+ * Get the return address for a single stackframe and return a pointer to the
+ * next frame tail.
+ */
+static unsigned long unwind_user_frame(stack_trace_consume_fn consume_entry,
+				       void *cookie, unsigned long fp,
+				       unsigned long reg_ra)
+{
+	struct stackframe buftail;
+	unsigned long ra = 0;
+	unsigned long __user *user_frame_tail =
+		(unsigned long __user *)(fp - sizeof(struct stackframe));
+
+	/* Check accessibility of one struct frame_tail beyond */
+	if (!access_ok(user_frame_tail, sizeof(buftail)))
+		return 0;
+	if (__copy_from_user_inatomic(&buftail, user_frame_tail,
+				      sizeof(buftail)))
+		return 0;
+
+	ra = reg_ra ? : buftail.ra;
+
+	fp = buftail.fp;
+	if (!ra || !consume_entry(cookie, ra))
+		return 0;
+
+	return fp;
+}
+
+void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
+			  const struct pt_regs *regs)
+{
+	unsigned long fp = 0;
+
+	fp = regs->s0;
+	if (!consume_entry(cookie, regs->epc))
+		return;
+
+	fp = unwind_user_frame(consume_entry, cookie, fp, regs->ra);
+	while (fp && !(fp & 0x7))
+		fp = unwind_user_frame(consume_entry, cookie, fp, 0);
+}