1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * Stack depot - a stack trace storage that avoids duplication. 4 * 5 * Author: Alexander Potapenko <[email protected]> 6 * Copyright (C) 2016 Google, Inc. 7 * 8 * Based on the 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 /* 19 * Number of bits in the handle that stack depot doesn't use. Users may store 20 * information in them via stack_depot_set/get_extra_bits. 21 */ 22 #define STACK_DEPOT_EXTRA_BITS 5 23 24 /* 25 * Using stack depot requires its initialization, which can be done in 3 ways: 26 * 27 * 1. Selecting CONFIG_STACKDEPOT_ALWAYS_INIT. This option is suitable in 28 * scenarios where it's known at compile time that stack depot will be used. 29 * Enabling this config makes the kernel initialize stack depot in mm_init(). 30 * 31 * 2. Calling stack_depot_request_early_init() during early boot, before 32 * stack_depot_early_init() in mm_init() completes. For example, this can 33 * be done when evaluating kernel boot parameters. 34 * 35 * 3. Calling stack_depot_init(). Possible after boot is complete. This option 36 * is recommended for modules initialized later in the boot process, after 37 * mm_init() completes. 38 * 39 * stack_depot_init() and stack_depot_request_early_init() can be called 40 * regardless of whether CONFIG_STACKDEPOT is enabled and are no-op when this 41 * config is disabled. The save/fetch/print stack depot functions can only be 42 * called from the code that makes sure CONFIG_STACKDEPOT is enabled _and_ 43 * initializes stack depot via one of the ways listed above. 44 */ 45 #ifdef CONFIG_STACKDEPOT 46 int stack_depot_init(void); 47 48 void __init stack_depot_request_early_init(void); 49 50 /* Must be only called from mm_init(). */ 51 int __init stack_depot_early_init(void); 52 #else 53 static inline int stack_depot_init(void) { return 0; } 54 55 static inline void stack_depot_request_early_init(void) { } 56 57 static inline int stack_depot_early_init(void) { return 0; } 58 #endif 59 60 depot_stack_handle_t __stack_depot_save(unsigned long *entries, 61 unsigned int nr_entries, 62 gfp_t gfp_flags, bool can_alloc); 63 64 depot_stack_handle_t stack_depot_save(unsigned long *entries, 65 unsigned int nr_entries, gfp_t gfp_flags); 66 67 unsigned int stack_depot_fetch(depot_stack_handle_t handle, 68 unsigned long **entries); 69 70 void stack_depot_print(depot_stack_handle_t stack); 71 72 int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size, 73 int spaces); 74 75 depot_stack_handle_t __must_check stack_depot_set_extra_bits( 76 depot_stack_handle_t handle, unsigned int extra_bits); 77 78 unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle); 79 80 #endif 81