4 files changed, 140 insertions, 11 deletions

diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 940de9173542..c5fa4adb23b6 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -22,4 +22,6 @@ obj-$(CONFIG_SMP)		+= smp.o
 
 obj-$(CONFIG_NUMA)		+= numa.o
 
+obj-$(CONFIG_UNWINDER_GUESS)	+= unwind_guess.o
+
 CPPFLAGS_vmlinux.lds		:= $(KBUILD_CFLAGS)
diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
index bfa0dfe8b7d7..839f0e963152 100644
--- a/arch/loongarch/kernel/process.c
+++ b/arch/loongarch/kernel/process.c
@@ -44,6 +44,7 @@
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/reg.h>
+#include <asm/unwind.h>
 #include <asm/vdso.h>
 
 /*
@@ -183,6 +184,66 @@ unsigned long __get_wchan(struct task_struct *task)
 	return 0;
 }
 
+bool in_irq_stack(unsigned long stack, struct stack_info *info)
+{
+	unsigned long nextsp;
+	unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
+	unsigned long end = begin + IRQ_STACK_START;
+
+	if (stack < begin || stack >= end)
+		return false;
+
+	nextsp = *(unsigned long *)end;
+	if (nextsp & (SZREG - 1))
+		return false;
+
+	info->begin = begin;
+	info->end = end;
+	info->next_sp = nextsp;
+	info->type = STACK_TYPE_IRQ;
+
+	return true;
+}
+
+bool in_task_stack(unsigned long stack, struct task_struct *task,
+			struct stack_info *info)
+{
+	unsigned long begin = (unsigned long)task_stack_page(task);
+	unsigned long end = begin + THREAD_SIZE - 32;
+
+	if (stack < begin || stack >= end)
+		return false;
+
+	info->begin = begin;
+	info->end = end;
+	info->next_sp = 0;
+	info->type = STACK_TYPE_TASK;
+
+	return true;
+}
+
+int get_stack_info(unsigned long stack, struct task_struct *task,
+		   struct stack_info *info)
+{
+	task = task ? : current;
+
+	if (!stack || stack & (SZREG - 1))
+		goto unknown;
+
+	if (in_task_stack(stack, task, info))
+		return 0;
+
+	if (task != current)
+		goto unknown;
+
+	if (in_irq_stack(stack, info))
+		return 0;
+
+unknown:
+	info->type = STACK_TYPE_UNKNOWN;
+	return -EINVAL;
+}
+
 unsigned long stack_top(void)
 {
 	unsigned long top = TASK_SIZE & PAGE_MASK;
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index 1bf58c65e2bf..f65fdf90d29e 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -43,6 +43,7 @@
 #include <asm/stacktrace.h>
 #include <asm/tlb.h>
 #include <asm/types.h>
+#include <asm/unwind.h>
 
 #include "access-helper.h"
 
@@ -64,19 +65,17 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
 			   const char *loglvl, bool user)
 {
 	unsigned long addr;
-	unsigned long *sp = (unsigned long *)(regs->regs[3] & ~3);
+	struct unwind_state state;
+	struct pt_regs *pregs = (struct pt_regs *)regs;
+
+	if (!task)
+		task = current;
 
 	printk("%sCall Trace:", loglvl);
-#ifdef CONFIG_KALLSYMS
-	printk("%s\n", loglvl);
-#endif
-	while (!kstack_end(sp)) {
-		if (__get_addr(&addr, sp++, user)) {
-			printk("%s (Bad stack address)", loglvl);
-			break;
-		}
-		if (__kernel_text_address(addr))
-			print_ip_sym(loglvl, addr);
+	for (unwind_start(&state, task, pregs);
+	      !unwind_done(&state); unwind_next_frame(&state)) {
+		addr = unwind_get_return_address(&state);
+		print_ip_sym(loglvl, addr);
 	}
 	printk("%s\n", loglvl);
 }
diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
new file mode 100644
index 000000000000..5afa6064d73e
--- /dev/null
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#include <linux/kernel.h>
+
+#include <asm/unwind.h>
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+	if (unwind_done(state))
+		return 0;
+	else if (state->first)
+		return state->pc;
+
+	return *(unsigned long *)(state->sp);
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+void unwind_start(struct unwind_state *state, struct task_struct *task,
+		    struct pt_regs *regs)
+{
+	memset(state, 0, sizeof(*state));
+
+	if (regs) {
+		state->sp = regs->regs[3];
+		state->pc = regs->csr_era;
+	}
+
+	state->task = task;
+	state->first = true;
+
+	get_stack_info(state->sp, state->task, &state->stack_info);
+
+	if (!unwind_done(state) && !__kernel_text_address(state->pc))
+		unwind_next_frame(state);
+}
+EXPORT_SYMBOL_GPL(unwind_start);
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+	struct stack_info *info = &state->stack_info;
+	unsigned long addr;
+
+	if (unwind_done(state))
+		return false;
+
+	if (state->first)
+		state->first = false;
+
+	do {
+		for (state->sp += sizeof(unsigned long);
+		     state->sp < info->end;
+		     state->sp += sizeof(unsigned long)) {
+			addr = *(unsigned long *)(state->sp);
+
+			if (__kernel_text_address(addr))
+				return true;
+		}
+
+		state->sp = info->next_sp;
+
+	} while (!get_stack_info(state->sp, state->task, info));
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(unwind_next_frame);