1 files changed, 64 insertions, 10 deletions

diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 64a9c093aef9..d4355c770c36 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -16,12 +16,24 @@
 
 #ifdef CONFIG_FRAME_POINTER
 
-extern asmlinkage void ret_from_exception(void);
+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) {
@@ -41,28 +53,27 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
 	}
 
 	for (;;) {
-		unsigned long low, high;
 		struct stackframe *frame;
 
 		if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
 			break;
 
-		/* Validate frame pointer */
-		low = sp + sizeof(struct stackframe);
-		high = ALIGN(sp, THREAD_SIZE);
-		if (unlikely(fp < low || fp > high || fp & 0x7))
+		if (unlikely(!fp_is_valid(fp, sp)))
 			break;
+
 		/* Unwind stack frame */
 		frame = (struct stackframe *)fp - 1;
 		sp = fp;
-		if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
+		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 = frame->fp;
-			pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
+			pc = ftrace_graph_ret_addr(current, &graph_idx, frame->ra,
 						   &frame->ra);
-			if (pc == (unsigned long)ret_from_exception) {
+			if (pc >= (unsigned long)handle_exception &&
+			    pc < (unsigned long)&ret_from_exception_end) {
 				if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
 					break;
 
@@ -148,8 +159,51 @@ unsigned long __get_wchan(struct task_struct *task)
 	return pc;
 }
 
-noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
+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);
+}