diff options
Diffstat (limited to 'lib/stackdepot.c')
| -rw-r--r-- | lib/stackdepot.c | 193 |
1 files changed, 152 insertions, 41 deletions
diff --git a/lib/stackdepot.c b/lib/stackdepot.c index df9179f4f441..5ca0d086ef4a 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -11,7 +11,7 @@ * Instead, stack depot maintains a hashtable of unique stacktraces. Since alloc * and free stacks repeat a lot, we save about 100x space. * Stacks are never removed from depot, so we store them contiguously one after - * another in a contiguos memory allocation. + * another in a contiguous memory allocation. * * Author: Alexander Potapenko <glider@google.com> * Copyright (C) 2016 Google, Inc. @@ -20,10 +20,10 @@ */ #include <linux/gfp.h> -#include <linux/interrupt.h> #include <linux/jhash.h> #include <linux/kernel.h> #include <linux/mm.h> +#include <linux/mutex.h> #include <linux/percpu.h> #include <linux/printk.h> #include <linux/slab.h> @@ -66,6 +66,9 @@ struct stack_record { unsigned long entries[]; /* Variable-sized array of entries. */ }; +static bool __stack_depot_want_early_init __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT); +static bool __stack_depot_early_init_passed __initdata; + static void *stack_slabs[STACK_ALLOC_MAX_SLABS]; static int depot_index; @@ -102,8 +105,8 @@ static bool init_stack_slab(void **prealloc) } /* Allocation of a new stack in raw storage */ -static struct stack_record *depot_alloc_stack(unsigned long *entries, int size, - u32 hash, void **prealloc, gfp_t alloc_flags) +static struct stack_record * +depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) { struct stack_record *stack; size_t required_size = struct_size(stack, entries, size); @@ -162,19 +165,61 @@ static int __init is_stack_depot_disabled(char *str) } early_param("stack_depot_disable", is_stack_depot_disabled); -int __init stack_depot_init(void) +void __init stack_depot_want_early_init(void) +{ + /* Too late to request early init now */ + WARN_ON(__stack_depot_early_init_passed); + + __stack_depot_want_early_init = true; +} + +int __init stack_depot_early_init(void) { - if (!stack_depot_disable) { - size_t size = (STACK_HASH_SIZE * sizeof(struct stack_record *)); - int i; + size_t size; + + /* This is supposed to be called only once, from mm_init() */ + if (WARN_ON(__stack_depot_early_init_passed)) + return 0; + + __stack_depot_early_init_passed = true; + + if (!__stack_depot_want_early_init || stack_depot_disable) + return 0; + + size = (STACK_HASH_SIZE * sizeof(struct stack_record *)); + pr_info("Stack Depot early init allocating hash table with memblock_alloc, %zu bytes\n", + size); + stack_table = memblock_alloc(size, SMP_CACHE_BYTES); - stack_table = memblock_alloc(size, size); - for (i = 0; i < STACK_HASH_SIZE; i++) - stack_table[i] = NULL; + if (!stack_table) { + pr_err("Stack Depot hash table allocation failed, disabling\n"); + stack_depot_disable = true; + return -ENOMEM; } + return 0; } +int stack_depot_init(void) +{ + static DEFINE_MUTEX(stack_depot_init_mutex); + int ret = 0; + + mutex_lock(&stack_depot_init_mutex); + if (!stack_depot_disable && !stack_table) { + pr_info("Stack Depot allocating hash table with kvcalloc\n"); + stack_table = kvcalloc(STACK_HASH_SIZE, sizeof(struct stack_record *), GFP_KERNEL); + if (!stack_table) { + pr_err("Stack Depot hash table allocation failed, disabling\n"); + stack_depot_disable = true; + ret = -ENOMEM; + } + } + mutex_unlock(&stack_depot_init_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(stack_depot_init); + /* Calculate hash for a stack */ static inline u32 hash_stack(unsigned long *entries, unsigned int size) { @@ -215,6 +260,49 @@ static inline struct stack_record *find_stack(struct stack_record *bucket, } /** + * stack_depot_snprint - print stack entries from a depot into a buffer + * + * @handle: Stack depot handle which was returned from + * stack_depot_save(). + * @buf: Pointer to the print buffer + * + * @size: Size of the print buffer + * + * @spaces: Number of leading spaces to print + * + * Return: Number of bytes printed. + */ +int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size, + int spaces) +{ + unsigned long *entries; + unsigned int nr_entries; + + nr_entries = stack_depot_fetch(handle, &entries); + return nr_entries ? stack_trace_snprint(buf, size, entries, nr_entries, + spaces) : 0; +} +EXPORT_SYMBOL_GPL(stack_depot_snprint); + +/** + * stack_depot_print - print stack entries from a depot + * + * @stack: Stack depot handle which was returned from + * stack_depot_save(). + * + */ +void stack_depot_print(depot_stack_handle_t stack) +{ + unsigned long *entries; + unsigned int nr_entries; + + nr_entries = stack_depot_fetch(stack, &entries); + if (nr_entries > 0) + stack_trace_print(entries, nr_entries, 0); +} +EXPORT_SYMBOL_GPL(stack_depot_print); + +/** * stack_depot_fetch - Fetch stack entries from a depot * * @handle: Stack depot handle which was returned from @@ -232,6 +320,9 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, struct stack_record *stack; *entries = NULL; + if (!handle) + return 0; + if (parts.slabindex > depot_index) { WARN(1, "slab index %d out of bounds (%d) for stack id %08x\n", parts.slabindex, depot_index, handle); @@ -248,17 +339,31 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle, EXPORT_SYMBOL_GPL(stack_depot_fetch); /** - * stack_depot_save - Save a stack trace from an array + * __stack_depot_save - Save a stack trace from an array * * @entries: Pointer to storage array * @nr_entries: Size of the storage array * @alloc_flags: Allocation gfp flags + * @can_alloc: Allocate stack slabs (increased chance of failure if false) + * + * Saves a stack trace from @entries array of size @nr_entries. If @can_alloc is + * %true, is allowed to replenish the stack slab pool in case no space is left + * (allocates using GFP flags of @alloc_flags). If @can_alloc is %false, avoids + * any allocations and will fail if no space is left to store the stack trace. * - * Return: The handle of the stack struct stored in depot + * If the stack trace in @entries is from an interrupt, only the portion up to + * interrupt entry is saved. + * + * Context: Any context, but setting @can_alloc to %false is required if + * alloc_pages() cannot be used from the current context. Currently + * this is the case from contexts where neither %GFP_ATOMIC nor + * %GFP_NOWAIT can be used (NMI, raw_spin_lock). + * + * Return: The handle of the stack struct stored in depot, 0 on failure. */ -depot_stack_handle_t stack_depot_save(unsigned long *entries, - unsigned int nr_entries, - gfp_t alloc_flags) +depot_stack_handle_t __stack_depot_save(unsigned long *entries, + unsigned int nr_entries, + gfp_t alloc_flags, bool can_alloc) { struct stack_record *found = NULL, **bucket; depot_stack_handle_t retval = 0; @@ -267,6 +372,16 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries, unsigned long flags; u32 hash; + /* + * If this stack trace is from an interrupt, including anything before + * interrupt entry usually leads to unbounded stackdepot growth. + * + * Because use of filter_irq_stacks() is a requirement to ensure + * stackdepot can efficiently deduplicate interrupt stacks, always + * filter_irq_stacks() to simplify all callers' use of stackdepot. + */ + nr_entries = filter_irq_stacks(entries, nr_entries); + if (unlikely(nr_entries == 0) || stack_depot_disable) goto fast_exit; @@ -291,7 +406,7 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries, * The smp_load_acquire() here pairs with smp_store_release() to * |next_slab_inited| in depot_alloc_stack() and init_stack_slab(). */ - if (unlikely(!smp_load_acquire(&next_slab_inited))) { + if (unlikely(can_alloc && !smp_load_acquire(&next_slab_inited))) { /* * Zero out zone modifiers, as we don't have specific zone * requirements. Keep the flags related to allocation in atomic @@ -309,9 +424,8 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries, found = find_stack(*bucket, entries, nr_entries, hash); if (!found) { - struct stack_record *new = - depot_alloc_stack(entries, nr_entries, - hash, &prealloc, alloc_flags); + struct stack_record *new = depot_alloc_stack(entries, nr_entries, hash, &prealloc); + if (new) { new->next = *bucket; /* @@ -340,27 +454,24 @@ exit: fast_exit: return retval; } -EXPORT_SYMBOL_GPL(stack_depot_save); +EXPORT_SYMBOL_GPL(__stack_depot_save); -static inline int in_irqentry_text(unsigned long ptr) -{ - return (ptr >= (unsigned long)&__irqentry_text_start && - ptr < (unsigned long)&__irqentry_text_end) || - (ptr >= (unsigned long)&__softirqentry_text_start && - ptr < (unsigned long)&__softirqentry_text_end); -} - -unsigned int filter_irq_stacks(unsigned long *entries, - unsigned int nr_entries) +/** + * stack_depot_save - Save a stack trace from an array + * + * @entries: Pointer to storage array + * @nr_entries: Size of the storage array + * @alloc_flags: Allocation gfp flags + * + * Context: Contexts where allocations via alloc_pages() are allowed. + * See __stack_depot_save() for more details. + * + * Return: The handle of the stack struct stored in depot, 0 on failure. + */ +depot_stack_handle_t stack_depot_save(unsigned long *entries, + unsigned int nr_entries, + gfp_t alloc_flags) { - unsigned int i; - - for (i = 0; i < nr_entries; i++) { - if (in_irqentry_text(entries[i])) { - /* Include the irqentry function into the stack. */ - return i + 1; - } - } - return nr_entries; + return __stack_depot_save(entries, nr_entries, alloc_flags, true); } -EXPORT_SYMBOL_GPL(filter_irq_stacks); +EXPORT_SYMBOL_GPL(stack_depot_save); |