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![Dave Chinner](/assets/img/avatar_default.png)
The stackdepot code is used by KASAN and lockdep for recoding stack traces. Both of these track allocation context information, and so their internal allocations must obey the caller allocation contexts to avoid generating their own false positive warnings that have nothing to do with the code they are instrumenting/tracking. We also don't want recording stack traces to deplete emergency memory reserves - debug code is useless if it creates new issues that can't be replicated when the debug code is disabled. Switch the stackdepot allocation masking to use gfp_nested_mask() to address these issues. gfp_nested_mask() also strips GFP_ZONEMASK naturally, so that greatly simplifies this code. Link: https://lkml.kernel.org/r/20240430054604.4169568-3-david@fromorbit.com Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Andrey Konovalov <andreyknvl@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
810 lines
22 KiB
C
810 lines
22 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Stack depot - a stack trace storage that avoids duplication.
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*
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* Internally, stack depot maintains a hash table of unique stacktraces. The
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* stack traces themselves are stored contiguously one after another in a set
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* of separate page allocations.
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*
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* Author: Alexander Potapenko <glider@google.com>
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* Copyright (C) 2016 Google, Inc.
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*
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* Based on the code by Dmitry Chernenkov.
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*/
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#define pr_fmt(fmt) "stackdepot: " fmt
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#include <linux/debugfs.h>
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#include <linux/gfp.h>
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#include <linux/jhash.h>
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#include <linux/kernel.h>
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#include <linux/kmsan.h>
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#include <linux/list.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/poison.h>
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#include <linux/printk.h>
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#include <linux/rculist.h>
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#include <linux/rcupdate.h>
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#include <linux/refcount.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/stacktrace.h>
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#include <linux/stackdepot.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/memblock.h>
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#include <linux/kasan-enabled.h>
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#define DEPOT_POOLS_CAP 8192
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/* The pool_index is offset by 1 so the first record does not have a 0 handle. */
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#define DEPOT_MAX_POOLS \
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(((1LL << (DEPOT_POOL_INDEX_BITS)) - 1 < DEPOT_POOLS_CAP) ? \
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(1LL << (DEPOT_POOL_INDEX_BITS)) - 1 : DEPOT_POOLS_CAP)
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static bool stack_depot_disabled;
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static bool __stack_depot_early_init_requested __initdata = IS_ENABLED(CONFIG_STACKDEPOT_ALWAYS_INIT);
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static bool __stack_depot_early_init_passed __initdata;
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/* Use one hash table bucket per 16 KB of memory. */
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#define STACK_HASH_TABLE_SCALE 14
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/* Limit the number of buckets between 4K and 1M. */
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#define STACK_BUCKET_NUMBER_ORDER_MIN 12
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#define STACK_BUCKET_NUMBER_ORDER_MAX 20
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/* Initial seed for jhash2. */
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#define STACK_HASH_SEED 0x9747b28c
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/* Hash table of stored stack records. */
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static struct list_head *stack_table;
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/* Fixed order of the number of table buckets. Used when KASAN is enabled. */
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static unsigned int stack_bucket_number_order;
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/* Hash mask for indexing the table. */
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static unsigned int stack_hash_mask;
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/* Array of memory regions that store stack records. */
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static void *stack_pools[DEPOT_MAX_POOLS];
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/* Newly allocated pool that is not yet added to stack_pools. */
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static void *new_pool;
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/* Number of pools in stack_pools. */
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static int pools_num;
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/* Offset to the unused space in the currently used pool. */
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static size_t pool_offset = DEPOT_POOL_SIZE;
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/* Freelist of stack records within stack_pools. */
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static LIST_HEAD(free_stacks);
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/* The lock must be held when performing pool or freelist modifications. */
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static DEFINE_RAW_SPINLOCK(pool_lock);
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/* Statistics counters for debugfs. */
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enum depot_counter_id {
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DEPOT_COUNTER_REFD_ALLOCS,
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DEPOT_COUNTER_REFD_FREES,
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DEPOT_COUNTER_REFD_INUSE,
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DEPOT_COUNTER_FREELIST_SIZE,
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DEPOT_COUNTER_PERSIST_COUNT,
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DEPOT_COUNTER_PERSIST_BYTES,
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DEPOT_COUNTER_COUNT,
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};
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static long counters[DEPOT_COUNTER_COUNT];
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static const char *const counter_names[] = {
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[DEPOT_COUNTER_REFD_ALLOCS] = "refcounted_allocations",
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[DEPOT_COUNTER_REFD_FREES] = "refcounted_frees",
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[DEPOT_COUNTER_REFD_INUSE] = "refcounted_in_use",
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[DEPOT_COUNTER_FREELIST_SIZE] = "freelist_size",
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[DEPOT_COUNTER_PERSIST_COUNT] = "persistent_count",
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[DEPOT_COUNTER_PERSIST_BYTES] = "persistent_bytes",
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};
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static_assert(ARRAY_SIZE(counter_names) == DEPOT_COUNTER_COUNT);
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static int __init disable_stack_depot(char *str)
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{
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return kstrtobool(str, &stack_depot_disabled);
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}
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early_param("stack_depot_disable", disable_stack_depot);
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void __init stack_depot_request_early_init(void)
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{
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/* Too late to request early init now. */
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WARN_ON(__stack_depot_early_init_passed);
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__stack_depot_early_init_requested = true;
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}
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/* Initialize list_head's within the hash table. */
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static void init_stack_table(unsigned long entries)
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{
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unsigned long i;
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for (i = 0; i < entries; i++)
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INIT_LIST_HEAD(&stack_table[i]);
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}
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/* Allocates a hash table via memblock. Can only be used during early boot. */
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int __init stack_depot_early_init(void)
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{
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unsigned long entries = 0;
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/* This function must be called only once, from mm_init(). */
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if (WARN_ON(__stack_depot_early_init_passed))
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return 0;
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__stack_depot_early_init_passed = true;
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/*
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* Print disabled message even if early init has not been requested:
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* stack_depot_init() will not print one.
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*/
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if (stack_depot_disabled) {
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pr_info("disabled\n");
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return 0;
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}
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/*
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* If KASAN is enabled, use the maximum order: KASAN is frequently used
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* in fuzzing scenarios, which leads to a large number of different
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* stack traces being stored in stack depot.
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*/
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if (kasan_enabled() && !stack_bucket_number_order)
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stack_bucket_number_order = STACK_BUCKET_NUMBER_ORDER_MAX;
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/*
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* Check if early init has been requested after setting
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* stack_bucket_number_order: stack_depot_init() uses its value.
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*/
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if (!__stack_depot_early_init_requested)
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return 0;
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/*
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* If stack_bucket_number_order is not set, leave entries as 0 to rely
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* on the automatic calculations performed by alloc_large_system_hash().
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*/
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if (stack_bucket_number_order)
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entries = 1UL << stack_bucket_number_order;
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pr_info("allocating hash table via alloc_large_system_hash\n");
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stack_table = alloc_large_system_hash("stackdepot",
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sizeof(struct list_head),
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entries,
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STACK_HASH_TABLE_SCALE,
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HASH_EARLY,
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NULL,
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&stack_hash_mask,
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1UL << STACK_BUCKET_NUMBER_ORDER_MIN,
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1UL << STACK_BUCKET_NUMBER_ORDER_MAX);
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if (!stack_table) {
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pr_err("hash table allocation failed, disabling\n");
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stack_depot_disabled = true;
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return -ENOMEM;
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}
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if (!entries) {
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/*
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* Obtain the number of entries that was calculated by
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* alloc_large_system_hash().
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*/
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entries = stack_hash_mask + 1;
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}
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init_stack_table(entries);
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return 0;
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}
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/* Allocates a hash table via kvcalloc. Can be used after boot. */
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int stack_depot_init(void)
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{
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static DEFINE_MUTEX(stack_depot_init_mutex);
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unsigned long entries;
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int ret = 0;
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mutex_lock(&stack_depot_init_mutex);
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if (stack_depot_disabled || stack_table)
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goto out_unlock;
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/*
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* Similarly to stack_depot_early_init, use stack_bucket_number_order
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* if assigned, and rely on automatic scaling otherwise.
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*/
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if (stack_bucket_number_order) {
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entries = 1UL << stack_bucket_number_order;
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} else {
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int scale = STACK_HASH_TABLE_SCALE;
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entries = nr_free_buffer_pages();
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entries = roundup_pow_of_two(entries);
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if (scale > PAGE_SHIFT)
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entries >>= (scale - PAGE_SHIFT);
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else
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entries <<= (PAGE_SHIFT - scale);
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}
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if (entries < 1UL << STACK_BUCKET_NUMBER_ORDER_MIN)
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entries = 1UL << STACK_BUCKET_NUMBER_ORDER_MIN;
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if (entries > 1UL << STACK_BUCKET_NUMBER_ORDER_MAX)
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entries = 1UL << STACK_BUCKET_NUMBER_ORDER_MAX;
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pr_info("allocating hash table of %lu entries via kvcalloc\n", entries);
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stack_table = kvcalloc(entries, sizeof(struct list_head), GFP_KERNEL);
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if (!stack_table) {
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pr_err("hash table allocation failed, disabling\n");
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stack_depot_disabled = true;
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ret = -ENOMEM;
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goto out_unlock;
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}
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stack_hash_mask = entries - 1;
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init_stack_table(entries);
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out_unlock:
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mutex_unlock(&stack_depot_init_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(stack_depot_init);
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/*
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* Initializes new stack pool, and updates the list of pools.
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*/
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static bool depot_init_pool(void **prealloc)
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{
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lockdep_assert_held(&pool_lock);
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if (unlikely(pools_num >= DEPOT_MAX_POOLS)) {
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/* Bail out if we reached the pool limit. */
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WARN_ON_ONCE(pools_num > DEPOT_MAX_POOLS); /* should never happen */
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WARN_ON_ONCE(!new_pool); /* to avoid unnecessary pre-allocation */
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WARN_ONCE(1, "Stack depot reached limit capacity");
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return false;
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}
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if (!new_pool && *prealloc) {
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/* We have preallocated memory, use it. */
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WRITE_ONCE(new_pool, *prealloc);
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*prealloc = NULL;
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}
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if (!new_pool)
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return false; /* new_pool and *prealloc are NULL */
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/* Save reference to the pool to be used by depot_fetch_stack(). */
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stack_pools[pools_num] = new_pool;
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/*
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* Stack depot tries to keep an extra pool allocated even before it runs
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* out of space in the currently used pool.
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*
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* To indicate that a new preallocation is needed new_pool is reset to
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* NULL; do not reset to NULL if we have reached the maximum number of
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* pools.
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*/
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if (pools_num < DEPOT_MAX_POOLS)
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WRITE_ONCE(new_pool, NULL);
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else
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WRITE_ONCE(new_pool, STACK_DEPOT_POISON);
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/* Pairs with concurrent READ_ONCE() in depot_fetch_stack(). */
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WRITE_ONCE(pools_num, pools_num + 1);
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ASSERT_EXCLUSIVE_WRITER(pools_num);
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pool_offset = 0;
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return true;
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}
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/* Keeps the preallocated memory to be used for a new stack depot pool. */
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static void depot_keep_new_pool(void **prealloc)
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{
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lockdep_assert_held(&pool_lock);
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/*
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* If a new pool is already saved or the maximum number of
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* pools is reached, do not use the preallocated memory.
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*/
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if (new_pool)
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return;
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WRITE_ONCE(new_pool, *prealloc);
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*prealloc = NULL;
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}
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/*
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* Try to initialize a new stack record from the current pool, a cached pool, or
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* the current pre-allocation.
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*/
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static struct stack_record *depot_pop_free_pool(void **prealloc, size_t size)
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{
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struct stack_record *stack;
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void *current_pool;
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u32 pool_index;
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lockdep_assert_held(&pool_lock);
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if (pool_offset + size > DEPOT_POOL_SIZE) {
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if (!depot_init_pool(prealloc))
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return NULL;
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}
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if (WARN_ON_ONCE(pools_num < 1))
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return NULL;
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pool_index = pools_num - 1;
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current_pool = stack_pools[pool_index];
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if (WARN_ON_ONCE(!current_pool))
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return NULL;
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stack = current_pool + pool_offset;
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/* Pre-initialize handle once. */
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stack->handle.pool_index_plus_1 = pool_index + 1;
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stack->handle.offset = pool_offset >> DEPOT_STACK_ALIGN;
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stack->handle.extra = 0;
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INIT_LIST_HEAD(&stack->hash_list);
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pool_offset += size;
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return stack;
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}
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/* Try to find next free usable entry from the freelist. */
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static struct stack_record *depot_pop_free(void)
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{
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struct stack_record *stack;
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lockdep_assert_held(&pool_lock);
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if (list_empty(&free_stacks))
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return NULL;
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/*
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* We maintain the invariant that the elements in front are least
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* recently used, and are therefore more likely to be associated with an
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* RCU grace period in the past. Consequently it is sufficient to only
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* check the first entry.
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*/
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stack = list_first_entry(&free_stacks, struct stack_record, free_list);
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if (!poll_state_synchronize_rcu(stack->rcu_state))
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return NULL;
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list_del(&stack->free_list);
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counters[DEPOT_COUNTER_FREELIST_SIZE]--;
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return stack;
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}
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static inline size_t depot_stack_record_size(struct stack_record *s, unsigned int nr_entries)
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{
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const size_t used = flex_array_size(s, entries, nr_entries);
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const size_t unused = sizeof(s->entries) - used;
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WARN_ON_ONCE(sizeof(s->entries) < used);
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return ALIGN(sizeof(struct stack_record) - unused, 1 << DEPOT_STACK_ALIGN);
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}
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/* Allocates a new stack in a stack depot pool. */
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static struct stack_record *
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depot_alloc_stack(unsigned long *entries, unsigned int nr_entries, u32 hash, depot_flags_t flags, void **prealloc)
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{
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struct stack_record *stack = NULL;
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size_t record_size;
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lockdep_assert_held(&pool_lock);
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/* This should already be checked by public API entry points. */
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if (WARN_ON_ONCE(!nr_entries))
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return NULL;
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/* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */
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if (nr_entries > CONFIG_STACKDEPOT_MAX_FRAMES)
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nr_entries = CONFIG_STACKDEPOT_MAX_FRAMES;
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if (flags & STACK_DEPOT_FLAG_GET) {
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/*
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* Evictable entries have to allocate the max. size so they may
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* safely be re-used by differently sized allocations.
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*/
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record_size = depot_stack_record_size(stack, CONFIG_STACKDEPOT_MAX_FRAMES);
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stack = depot_pop_free();
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} else {
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record_size = depot_stack_record_size(stack, nr_entries);
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}
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if (!stack) {
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stack = depot_pop_free_pool(prealloc, record_size);
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if (!stack)
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return NULL;
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}
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/* Save the stack trace. */
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stack->hash = hash;
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stack->size = nr_entries;
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/* stack->handle is already filled in by depot_pop_free_pool(). */
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memcpy(stack->entries, entries, flex_array_size(stack, entries, nr_entries));
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if (flags & STACK_DEPOT_FLAG_GET) {
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refcount_set(&stack->count, 1);
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counters[DEPOT_COUNTER_REFD_ALLOCS]++;
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counters[DEPOT_COUNTER_REFD_INUSE]++;
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} else {
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/* Warn on attempts to switch to refcounting this entry. */
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refcount_set(&stack->count, REFCOUNT_SATURATED);
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counters[DEPOT_COUNTER_PERSIST_COUNT]++;
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counters[DEPOT_COUNTER_PERSIST_BYTES] += record_size;
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}
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/*
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* Let KMSAN know the stored stack record is initialized. This shall
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* prevent false positive reports if instrumented code accesses it.
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*/
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kmsan_unpoison_memory(stack, record_size);
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return stack;
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}
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static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle)
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{
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const int pools_num_cached = READ_ONCE(pools_num);
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union handle_parts parts = { .handle = handle };
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void *pool;
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u32 pool_index = parts.pool_index_plus_1 - 1;
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size_t offset = parts.offset << DEPOT_STACK_ALIGN;
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struct stack_record *stack;
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lockdep_assert_not_held(&pool_lock);
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if (pool_index >= pools_num_cached) {
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WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n",
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pool_index, pools_num_cached, handle);
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return NULL;
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}
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pool = stack_pools[pool_index];
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if (WARN_ON(!pool))
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return NULL;
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stack = pool + offset;
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if (WARN_ON(!refcount_read(&stack->count)))
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return NULL;
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return stack;
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}
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/* Links stack into the freelist. */
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static void depot_free_stack(struct stack_record *stack)
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{
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unsigned long flags;
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lockdep_assert_not_held(&pool_lock);
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raw_spin_lock_irqsave(&pool_lock, flags);
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printk_deferred_enter();
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/*
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* Remove the entry from the hash list. Concurrent list traversal may
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* still observe the entry, but since the refcount is zero, this entry
|
|
* will no longer be considered as valid.
|
|
*/
|
|
list_del_rcu(&stack->hash_list);
|
|
|
|
/*
|
|
* Due to being used from constrained contexts such as the allocators,
|
|
* NMI, or even RCU itself, stack depot cannot rely on primitives that
|
|
* would sleep (such as synchronize_rcu()) or recursively call into
|
|
* stack depot again (such as call_rcu()).
|
|
*
|
|
* Instead, get an RCU cookie, so that we can ensure this entry isn't
|
|
* moved onto another list until the next grace period, and concurrent
|
|
* RCU list traversal remains safe.
|
|
*/
|
|
stack->rcu_state = get_state_synchronize_rcu();
|
|
|
|
/*
|
|
* Add the entry to the freelist tail, so that older entries are
|
|
* considered first - their RCU cookie is more likely to no longer be
|
|
* associated with the current grace period.
|
|
*/
|
|
list_add_tail(&stack->free_list, &free_stacks);
|
|
|
|
counters[DEPOT_COUNTER_FREELIST_SIZE]++;
|
|
counters[DEPOT_COUNTER_REFD_FREES]++;
|
|
counters[DEPOT_COUNTER_REFD_INUSE]--;
|
|
|
|
printk_deferred_exit();
|
|
raw_spin_unlock_irqrestore(&pool_lock, flags);
|
|
}
|
|
|
|
/* Calculates the hash for a stack. */
|
|
static inline u32 hash_stack(unsigned long *entries, unsigned int size)
|
|
{
|
|
return jhash2((u32 *)entries,
|
|
array_size(size, sizeof(*entries)) / sizeof(u32),
|
|
STACK_HASH_SEED);
|
|
}
|
|
|
|
/*
|
|
* Non-instrumented version of memcmp().
|
|
* Does not check the lexicographical order, only the equality.
|
|
*/
|
|
static inline
|
|
int stackdepot_memcmp(const unsigned long *u1, const unsigned long *u2,
|
|
unsigned int n)
|
|
{
|
|
for ( ; n-- ; u1++, u2++) {
|
|
if (*u1 != *u2)
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* Finds a stack in a bucket of the hash table. */
|
|
static inline struct stack_record *find_stack(struct list_head *bucket,
|
|
unsigned long *entries, int size,
|
|
u32 hash, depot_flags_t flags)
|
|
{
|
|
struct stack_record *stack, *ret = NULL;
|
|
|
|
/*
|
|
* Stack depot may be used from instrumentation that instruments RCU or
|
|
* tracing itself; use variant that does not call into RCU and cannot be
|
|
* traced.
|
|
*
|
|
* Note: Such use cases must take care when using refcounting to evict
|
|
* unused entries, because the stack record free-then-reuse code paths
|
|
* do call into RCU.
|
|
*/
|
|
rcu_read_lock_sched_notrace();
|
|
|
|
list_for_each_entry_rcu(stack, bucket, hash_list) {
|
|
if (stack->hash != hash || stack->size != size)
|
|
continue;
|
|
|
|
/*
|
|
* This may race with depot_free_stack() accessing the freelist
|
|
* management state unioned with @entries. The refcount is zero
|
|
* in that case and the below refcount_inc_not_zero() will fail.
|
|
*/
|
|
if (data_race(stackdepot_memcmp(entries, stack->entries, size)))
|
|
continue;
|
|
|
|
/*
|
|
* Try to increment refcount. If this succeeds, the stack record
|
|
* is valid and has not yet been freed.
|
|
*
|
|
* If STACK_DEPOT_FLAG_GET is not used, it is undefined behavior
|
|
* to then call stack_depot_put() later, and we can assume that
|
|
* a stack record is never placed back on the freelist.
|
|
*/
|
|
if ((flags & STACK_DEPOT_FLAG_GET) && !refcount_inc_not_zero(&stack->count))
|
|
continue;
|
|
|
|
ret = stack;
|
|
break;
|
|
}
|
|
|
|
rcu_read_unlock_sched_notrace();
|
|
|
|
return ret;
|
|
}
|
|
|
|
depot_stack_handle_t stack_depot_save_flags(unsigned long *entries,
|
|
unsigned int nr_entries,
|
|
gfp_t alloc_flags,
|
|
depot_flags_t depot_flags)
|
|
{
|
|
struct list_head *bucket;
|
|
struct stack_record *found = NULL;
|
|
depot_stack_handle_t handle = 0;
|
|
struct page *page = NULL;
|
|
void *prealloc = NULL;
|
|
bool can_alloc = depot_flags & STACK_DEPOT_FLAG_CAN_ALLOC;
|
|
unsigned long flags;
|
|
u32 hash;
|
|
|
|
if (WARN_ON(depot_flags & ~STACK_DEPOT_FLAGS_MASK))
|
|
return 0;
|
|
|
|
/*
|
|
* If this stack trace is from an interrupt, including anything before
|
|
* interrupt entry usually leads to unbounded stack depot growth.
|
|
*
|
|
* Since use of filter_irq_stacks() is a requirement to ensure stack
|
|
* depot can efficiently deduplicate interrupt stacks, always
|
|
* filter_irq_stacks() to simplify all callers' use of stack depot.
|
|
*/
|
|
nr_entries = filter_irq_stacks(entries, nr_entries);
|
|
|
|
if (unlikely(nr_entries == 0) || stack_depot_disabled)
|
|
return 0;
|
|
|
|
hash = hash_stack(entries, nr_entries);
|
|
bucket = &stack_table[hash & stack_hash_mask];
|
|
|
|
/* Fast path: look the stack trace up without locking. */
|
|
found = find_stack(bucket, entries, nr_entries, hash, depot_flags);
|
|
if (found)
|
|
goto exit;
|
|
|
|
/*
|
|
* Allocate memory for a new pool if required now:
|
|
* we won't be able to do that under the lock.
|
|
*/
|
|
if (unlikely(can_alloc && !READ_ONCE(new_pool))) {
|
|
page = alloc_pages(gfp_nested_mask(alloc_flags),
|
|
DEPOT_POOL_ORDER);
|
|
if (page)
|
|
prealloc = page_address(page);
|
|
}
|
|
|
|
raw_spin_lock_irqsave(&pool_lock, flags);
|
|
printk_deferred_enter();
|
|
|
|
/* Try to find again, to avoid concurrently inserting duplicates. */
|
|
found = find_stack(bucket, entries, nr_entries, hash, depot_flags);
|
|
if (!found) {
|
|
struct stack_record *new =
|
|
depot_alloc_stack(entries, nr_entries, hash, depot_flags, &prealloc);
|
|
|
|
if (new) {
|
|
/*
|
|
* This releases the stack record into the bucket and
|
|
* makes it visible to readers in find_stack().
|
|
*/
|
|
list_add_rcu(&new->hash_list, bucket);
|
|
found = new;
|
|
}
|
|
}
|
|
|
|
if (prealloc) {
|
|
/*
|
|
* Either stack depot already contains this stack trace, or
|
|
* depot_alloc_stack() did not consume the preallocated memory.
|
|
* Try to keep the preallocated memory for future.
|
|
*/
|
|
depot_keep_new_pool(&prealloc);
|
|
}
|
|
|
|
printk_deferred_exit();
|
|
raw_spin_unlock_irqrestore(&pool_lock, flags);
|
|
exit:
|
|
if (prealloc) {
|
|
/* Stack depot didn't use this memory, free it. */
|
|
free_pages((unsigned long)prealloc, DEPOT_POOL_ORDER);
|
|
}
|
|
if (found)
|
|
handle = found->handle.handle;
|
|
return handle;
|
|
}
|
|
EXPORT_SYMBOL_GPL(stack_depot_save_flags);
|
|
|
|
depot_stack_handle_t stack_depot_save(unsigned long *entries,
|
|
unsigned int nr_entries,
|
|
gfp_t alloc_flags)
|
|
{
|
|
return stack_depot_save_flags(entries, nr_entries, alloc_flags,
|
|
STACK_DEPOT_FLAG_CAN_ALLOC);
|
|
}
|
|
EXPORT_SYMBOL_GPL(stack_depot_save);
|
|
|
|
struct stack_record *__stack_depot_get_stack_record(depot_stack_handle_t handle)
|
|
{
|
|
if (!handle)
|
|
return NULL;
|
|
|
|
return depot_fetch_stack(handle);
|
|
}
|
|
|
|
unsigned int stack_depot_fetch(depot_stack_handle_t handle,
|
|
unsigned long **entries)
|
|
{
|
|
struct stack_record *stack;
|
|
|
|
*entries = NULL;
|
|
/*
|
|
* Let KMSAN know *entries is initialized. This shall prevent false
|
|
* positive reports if instrumented code accesses it.
|
|
*/
|
|
kmsan_unpoison_memory(entries, sizeof(*entries));
|
|
|
|
if (!handle || stack_depot_disabled)
|
|
return 0;
|
|
|
|
stack = depot_fetch_stack(handle);
|
|
/*
|
|
* Should never be NULL, otherwise this is a use-after-put (or just a
|
|
* corrupt handle).
|
|
*/
|
|
if (WARN(!stack, "corrupt handle or use after stack_depot_put()"))
|
|
return 0;
|
|
|
|
*entries = stack->entries;
|
|
return stack->size;
|
|
}
|
|
EXPORT_SYMBOL_GPL(stack_depot_fetch);
|
|
|
|
void stack_depot_put(depot_stack_handle_t handle)
|
|
{
|
|
struct stack_record *stack;
|
|
|
|
if (!handle || stack_depot_disabled)
|
|
return;
|
|
|
|
stack = depot_fetch_stack(handle);
|
|
/*
|
|
* Should always be able to find the stack record, otherwise this is an
|
|
* unbalanced put attempt (or corrupt handle).
|
|
*/
|
|
if (WARN(!stack, "corrupt handle or unbalanced stack_depot_put()"))
|
|
return;
|
|
|
|
if (refcount_dec_and_test(&stack->count))
|
|
depot_free_stack(stack);
|
|
}
|
|
EXPORT_SYMBOL_GPL(stack_depot_put);
|
|
|
|
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);
|
|
|
|
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);
|
|
|
|
depot_stack_handle_t __must_check stack_depot_set_extra_bits(
|
|
depot_stack_handle_t handle, unsigned int extra_bits)
|
|
{
|
|
union handle_parts parts = { .handle = handle };
|
|
|
|
/* Don't set extra bits on empty handles. */
|
|
if (!handle)
|
|
return 0;
|
|
|
|
parts.extra = extra_bits;
|
|
return parts.handle;
|
|
}
|
|
EXPORT_SYMBOL(stack_depot_set_extra_bits);
|
|
|
|
unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle)
|
|
{
|
|
union handle_parts parts = { .handle = handle };
|
|
|
|
return parts.extra;
|
|
}
|
|
EXPORT_SYMBOL(stack_depot_get_extra_bits);
|
|
|
|
static int stats_show(struct seq_file *seq, void *v)
|
|
{
|
|
/*
|
|
* data race ok: These are just statistics counters, and approximate
|
|
* statistics are ok for debugging.
|
|
*/
|
|
seq_printf(seq, "pools: %d\n", data_race(pools_num));
|
|
for (int i = 0; i < DEPOT_COUNTER_COUNT; i++)
|
|
seq_printf(seq, "%s: %ld\n", counter_names[i], data_race(counters[i]));
|
|
|
|
return 0;
|
|
}
|
|
DEFINE_SHOW_ATTRIBUTE(stats);
|
|
|
|
static int depot_debugfs_init(void)
|
|
{
|
|
struct dentry *dir;
|
|
|
|
if (stack_depot_disabled)
|
|
return 0;
|
|
|
|
dir = debugfs_create_dir("stackdepot", NULL);
|
|
debugfs_create_file("stats", 0444, dir, NULL, &stats_fops);
|
|
return 0;
|
|
}
|
|
late_initcall(depot_debugfs_init);
|