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 55 static inline int stack_depot_init(void) { return 0; } 56 57 static inline void stack_depot_want_early_init(void) { } 58 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