1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 * A generic stack depot implementation
4 *
5 * Author: Alexander Potapenko <glider@google.com>
6 * Copyright (C) 2016 Google, Inc.
7 *
8 * Based on code by Dmitry Chernenkov.
9 */
10
11 #ifndef _LINUX_STACKDEPOT_H
12 #define _LINUX_STACKDEPOT_H
13
14 #include <linux/gfp.h>
15
16 typedef u32 depot_stack_handle_t;
17 /*
18 * Number of bits in the handle that stack depot doesn't use. Users may store
19 * information in them.
20 */
21 #define STACK_DEPOT_EXTRA_BITS 5
22
23 depot_stack_handle_t __stack_depot_save(unsigned long *entries,
24 unsigned int nr_entries,
25 unsigned int extra_bits,
26 gfp_t gfp_flags, bool can_alloc);
27
28 /*
29 * Every user of stack depot has to call stack_depot_init() during its own init
30 * when it's decided that it will be calling stack_depot_save() later. This is
31 * recommended for e.g. modules initialized later in the boot process, when
32 * slab_is_available() is true.
33 *
34 * The alternative is to select STACKDEPOT_ALWAYS_INIT to have stack depot
35 * enabled as part of mm_init(), for subsystems where it's known at compile time
36 * that stack depot will be used.
37 *
38 * Another alternative is to call stack_depot_want_early_init(), when the
39 * decision to use stack depot is taken e.g. when evaluating kernel boot
40 * parameters, which precedes the enablement point in mm_init().
41 *
42 * stack_depot_init() and stack_depot_want_early_init() can be called regardless
43 * of CONFIG_STACKDEPOT and are no-op when disabled. The actual save/fetch/print
44 * functions should only be called from code that makes sure CONFIG_STACKDEPOT
45 * is enabled.
46 */
47 #ifdef CONFIG_STACKDEPOT
48 int stack_depot_init(void);
49
50 void __init stack_depot_want_early_init(void);
51
52 /* This is supposed to be called only from mm_init() */
53 int __init stack_depot_early_init(void);
54 #else
stack_depot_init(void)55 static inline int stack_depot_init(void) { return 0; }
56
stack_depot_want_early_init(void)57 static inline void stack_depot_want_early_init(void) { }
58
stack_depot_early_init(void)59 static inline int stack_depot_early_init(void) { return 0; }
60 #endif
61
62 depot_stack_handle_t stack_depot_save(unsigned long *entries,
63 unsigned int nr_entries, gfp_t gfp_flags);
64
65 unsigned int stack_depot_fetch(depot_stack_handle_t handle,
66 unsigned long **entries);
67
68 unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle);
69
70 int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
71 int spaces);
72
73 void stack_depot_print(depot_stack_handle_t stack);
74
75 #endif
76