Commit 49232773 authored by Qing Zhang's avatar Qing Zhang Committed by Huacai Chen
Browse files

LoongArch: Add guess unwinder support 



Name "guess unwinder" comes from x86, it scans the stack and reports
every kernel text address it finds.

Unwinders can be used by dump_stack() and other stacktrace functions.

Three stages when we do unwind,
  1) unwind_start(), the prapare of unwinding, fill unwind_state.
  2) unwind_done(), judge whether the unwind process is finished or not.
  3) unwind_next_frame(), unwind the next frame.

Add get_stack_info() to get stack info. At present we have irq stack and
task stack. The next_sp is the key info between two types of stacks.

Dividing unwinder helps to add new unwinders in the future.

Signed-off-by: default avatarQing Zhang <zhangqing@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent dce6098b

arch/loongarch/Kconfig.debug

+9 −0
Original line number Diff line number Diff line 
config UNWINDER_GUESS

	bool "Guess unwinder"

	help

	  This option enables the "guess" unwinder for unwinding kernel stack

	  traces.  It scans the stack and reports every kernel text address it

	  finds.  Some of the addresses it reports may be incorrect.



	  While this option often produces false positives, it can still be

	  useful in many cases.

arch/loongarch/include/asm/stacktrace.h

+15 −0
Original line number Diff line number Diff line
@@ -10,6 +10,21 @@ 
#include <asm/loongarch.h>

#include <linux/stringify.h>



enum stack_type {

	STACK_TYPE_UNKNOWN,

	STACK_TYPE_IRQ,

	STACK_TYPE_TASK,

};



struct stack_info {

	enum stack_type type;

	unsigned long begin, end, next_sp;

};



bool in_irq_stack(unsigned long stack, struct stack_info *info);

bool in_task_stack(unsigned long stack, struct task_struct *task, struct stack_info *info);

int get_stack_info(unsigned long stack, struct task_struct *task, struct stack_info *info);



#define STR_LONG_L    __stringify(LONG_L)

#define STR_LONG_S    __stringify(LONG_S)

#define STR_LONGSIZE  __stringify(LONGSIZE)

arch/loongarch/include/asm/unwind.h

0 → 100644
+36 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Most of this ideas comes from x86.

 *

 * Copyright (C) 2022 Loongson Technology Corporation Limited

 */

#ifndef _ASM_UNWIND_H

#define _ASM_UNWIND_H



#include <linux/sched.h>



#include <asm/stacktrace.h>



struct unwind_state {

	struct stack_info stack_info;

	struct task_struct *task;

	bool first, error;

	unsigned long sp, pc;

};



void unwind_start(struct unwind_state *state,

		  struct task_struct *task, struct pt_regs *regs);

bool unwind_next_frame(struct unwind_state *state);

unsigned long unwind_get_return_address(struct unwind_state *state);



static inline bool unwind_done(struct unwind_state *state)

{

	return state->stack_info.type == STACK_TYPE_UNKNOWN;

}



static inline bool unwind_error(struct unwind_state *state)

{

	return state->error;

}



#endif /* _ASM_UNWIND_H */

arch/loongarch/kernel/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -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)

arch/loongarch/kernel/process.c

+61 −0
Original line number Diff line number Diff line
@@ -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;