include/linux/stackdepot.h

0001 /* SPDX-License-Identifier: GPL-2.0-or-later */
0002 /*
0003  * A generic stack depot implementation
0004  *
0005  * Author: Alexander Potapenko <glider@google.com>
0006  * Copyright (C) 2016 Google, Inc.
0007  *
0008  * Based on code by Dmitry Chernenkov.
0009  */
0010
0011 #ifndef _LINUX_STACKDEPOT_H
0012 #define _LINUX_STACKDEPOT_H
0013
0014 #include <linux/gfp.h>
0015
0016 typedef u32 depot_stack_handle_t;
0017
0018 depot_stack_handle_t __stack_depot_save(unsigned long *entries,
0019                     unsigned int nr_entries,
0020                     gfp_t gfp_flags, bool can_alloc);
0021
0022 /*
0023  * Every user of stack depot has to call stack_depot_init() during its own init
0024  * when it's decided that it will be calling stack_depot_save() later. This is
0025  * recommended for e.g. modules initialized later in the boot process, when
0026  * slab_is_available() is true.
0027  *
0028  * The alternative is to select STACKDEPOT_ALWAYS_INIT to have stack depot
0029  * enabled as part of mm_init(), for subsystems where it's known at compile time
0030  * that stack depot will be used.
0031  *
0032  * Another alternative is to call stack_depot_want_early_init(), when the
0033  * decision to use stack depot is taken e.g. when evaluating kernel boot
0034  * parameters, which precedes the enablement point in mm_init().
0035  *
0036  * stack_depot_init() and stack_depot_want_early_init() can be called regardless
0037  * of CONFIG_STACKDEPOT and are no-op when disabled. The actual save/fetch/print
0038  * functions should only be called from code that makes sure CONFIG_STACKDEPOT
0039  * is enabled.
0040  */
0041 #ifdef CONFIG_STACKDEPOT
0042 int stack_depot_init(void);
0043
0044 void __init stack_depot_want_early_init(void);
0045
0046 /* This is supposed to be called only from mm_init() */
0047 int __init stack_depot_early_init(void);
0048 #else
0049 static inline int stack_depot_init(void) { return 0; }
0050
0051 static inline void stack_depot_want_early_init(void) { }
0052
0053 static inline int stack_depot_early_init(void)  { return 0; }
0054 #endif
0055
0056 depot_stack_handle_t stack_depot_save(unsigned long *entries,
0057                       unsigned int nr_entries, gfp_t gfp_flags);
0058
0059 unsigned int stack_depot_fetch(depot_stack_handle_t handle,
0060                    unsigned long **entries);
0061
0062 int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
0063                int spaces);
0064
0065 void stack_depot_print(depot_stack_handle_t stack);
0066
0067 #endif