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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Stack depot - a stack trace storage that avoids duplication.
*
* Author: Alexander Potapenko <glider@google.com>
* Copyright (C) 2016 Google, Inc.
*
* Based on the 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 via stack_depot_set/get_extra_bits.
*/
#define STACK_DEPOT_EXTRA_BITS 5
/*
* Using stack depot requires its initialization, which can be done in 3 ways:
*
* 1. Selecting CONFIG_STACKDEPOT_ALWAYS_INIT. This option is suitable in
* scenarios where it's known at compile time that stack depot will be used.
* Enabling this config makes the kernel initialize stack depot in mm_init().
*
* 2. Calling stack_depot_request_early_init() during early boot, before
* stack_depot_early_init() in mm_init() completes. For example, this can
* be done when evaluating kernel boot parameters.
*
* 3. Calling stack_depot_init(). Possible after boot is complete. This option
* is recommended for modules initialized later in the boot process, after
* mm_init() completes.
*
* stack_depot_init() and stack_depot_request_early_init() can be called
* regardless of whether CONFIG_STACKDEPOT is enabled and are no-op when this
* config is disabled. The save/fetch/print stack depot functions can only be
* called from the code that makes sure CONFIG_STACKDEPOT is enabled _and_
* initializes stack depot via one of the ways listed above.
*/
#ifdef CONFIG_STACKDEPOT
int stack_depot_init(void);
void __init stack_depot_request_early_init(void);
/* Must be only called 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_request_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, bool can_alloc);
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);
void stack_depot_print(depot_stack_handle_t stack);
int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
int spaces);
depot_stack_handle_t __must_check stack_depot_set_extra_bits(
depot_stack_handle_t handle, unsigned int extra_bits);
unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle);
#endif
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