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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* A generic stack depot implementation
*
* Author: Alexander Potapenko <glider@google.com>
* Copyright (C) 2016 Google, Inc.
*
* Based on code by Dmitry Chernenkov.
*/
#ifndef _LINUX_STACKDEPOT_H
#define _LINUX_STACKDEPOT_H
#include <linux/gfp.h>
typedef u32 depot_stack_handle_t;
/*
* Number of bits in the handle that stack depot doesn't use. Users may store
* information in them.
*/
#define STACK_DEPOT_EXTRA_BITS 5
depot_stack_handle_t __stack_depot_save(unsigned long *entries,
unsigned int nr_entries,
unsigned int extra_bits,
gfp_t gfp_flags, bool can_alloc);
/*
* Every user of stack depot has to call stack_depot_init() during its own init
* when it's decided that it will be calling stack_depot_save() later. This is
* recommended for e.g. modules initialized later in the boot process, when
* slab_is_available() is true.
*
* The alternative is to select STACKDEPOT_ALWAYS_INIT to have stack depot
* enabled as part of mm_init(), for subsystems where it's known at compile time
* that stack depot will be used.
*
* Another alternative is to call stack_depot_want_early_init(), when the
* decision to use stack depot is taken e.g. when evaluating kernel boot
* parameters, which precedes the enablement point in mm_init().
*
* stack_depot_init() and stack_depot_want_early_init() can be called regardless
* of CONFIG_STACKDEPOT and are no-op when disabled. The actual save/fetch/print
* functions should only be called from code that makes sure CONFIG_STACKDEPOT
* is enabled.
*/
#ifdef CONFIG_STACKDEPOT
int stack_depot_init(void);
void __init stack_depot_want_early_init(void);
/* This is supposed to be called only from mm_init() */
int __init stack_depot_early_init(void);
#else
static inline int stack_depot_init(void) { return 0; }
static inline void stack_depot_want_early_init(void) { }
static inline int stack_depot_early_init(void) { return 0; }
#endif
depot_stack_handle_t stack_depot_save(unsigned long *entries,
unsigned int nr_entries, gfp_t gfp_flags);
unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries);
unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle);
int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
int spaces);
void stack_depot_print(depot_stack_handle_t stack);
#endif
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