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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012 ARM Ltd.
*/
#ifndef __ASM_STACKTRACE_H
#define __ASM_STACKTRACE_H
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/types.h>
#include <asm/memory.h>
#include <asm/ptrace.h>
#include <asm/sdei.h>
enum stack_type {
STACK_TYPE_UNKNOWN,
STACK_TYPE_TASK,
STACK_TYPE_IRQ,
STACK_TYPE_OVERFLOW,
STACK_TYPE_SDEI_NORMAL,
STACK_TYPE_SDEI_CRITICAL,
__NR_STACK_TYPES
};
struct stack_info {
unsigned long low;
unsigned long high;
enum stack_type type;
};
/*
* A snapshot of a frame record or fp/lr register values, along with some
* accounting information necessary for robust unwinding.
*
* @fp: The fp value in the frame record (or the real fp)
* @pc: The fp value in the frame record (or the real lr)
*
* @stacks_done: Stacks which have been entirely unwound, for which it is no
* longer valid to unwind to.
*
* @prev_fp: The fp that pointed to this frame record, or a synthetic value
* of 0. This is used to ensure that within a stack, each
* subsequent frame record is at an increasing address.
* @prev_type: The type of stack this frame record was on, or a synthetic
* value of STACK_TYPE_UNKNOWN. This is used to detect a
* transition from one stack to another.
*
* @graph: When FUNCTION_GRAPH_TRACER is selected, holds the index of a
* replacement lr value in the ftrace graph stack.
*/
struct stackframe {
unsigned long fp;
unsigned long pc;
DECLARE_BITMAP(stacks_done, __NR_STACK_TYPES);
unsigned long prev_fp;
enum stack_type prev_type;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
int graph;
#endif
};
extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);
extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
int (*fn)(struct stackframe *, void *), void *data);
extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk);
DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
static inline bool on_irq_stack(unsigned long sp,
struct stack_info *info)
{
unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);
unsigned long high = low + IRQ_STACK_SIZE;
if (!low)
return false;
if (sp < low || sp >= high)
return false;
if (info) {
info->low = low;
info->high = high;
info->type = STACK_TYPE_IRQ;
}
return true;
}
static inline bool on_task_stack(const struct task_struct *tsk,
unsigned long sp,
struct stack_info *info)
{
unsigned long low = (unsigned long)task_stack_page(tsk);
unsigned long high = low + THREAD_SIZE;
if (sp < low || sp >= high)
return false;
if (info) {
info->low = low;
info->high = high;
info->type = STACK_TYPE_TASK;
}
return true;
}
#ifdef CONFIG_VMAP_STACK
DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
static inline bool on_overflow_stack(unsigned long sp,
struct stack_info *info)
{
unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);
unsigned long high = low + OVERFLOW_STACK_SIZE;
if (sp < low || sp >= high)
return false;
if (info) {
info->low = low;
info->high = high;
info->type = STACK_TYPE_OVERFLOW;
}
return true;
}
#else
static inline bool on_overflow_stack(unsigned long sp,
struct stack_info *info) { return false; }
#endif
/*
* We can only safely access per-cpu stacks from current in a non-preemptible
* context.
*/
static inline bool on_accessible_stack(const struct task_struct *tsk,
unsigned long sp,
struct stack_info *info)
{
if (info)
info->type = STACK_TYPE_UNKNOWN;
if (on_task_stack(tsk, sp, info))
return true;
if (tsk != current || preemptible())
return false;
if (on_irq_stack(sp, info))
return true;
if (on_overflow_stack(sp, info))
return true;
if (on_sdei_stack(sp, info))
return true;
return false;
}
static inline void start_backtrace(struct stackframe *frame,
unsigned long fp, unsigned long pc)
{
frame->fp = fp;
frame->pc = pc;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
frame->graph = 0;
#endif
/*
* Prime the first unwind.
*
* In unwind_frame() we'll check that the FP points to a valid stack,
* which can't be STACK_TYPE_UNKNOWN, and the first unwind will be
* treated as a transition to whichever stack that happens to be. The
* prev_fp value won't be used, but we set it to 0 such that it is
* definitely not an accessible stack address.
*/
bitmap_zero(frame->stacks_done, __NR_STACK_TYPES);
frame->prev_fp = 0;
frame->prev_type = STACK_TYPE_UNKNOWN;
}
#endif /* __ASM_STACKTRACE_H */
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