diff options
Diffstat (limited to 'kernel/dma/debug.c')
| -rw-r--r-- | kernel/dma/debug.c | 1601 |
1 files changed, 1601 insertions, 0 deletions
diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c new file mode 100644 index 000000000..3ff7089d1 --- /dev/null +++ b/kernel/dma/debug.c @@ -0,0 +1,1601 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2008 Advanced Micro Devices, Inc. + * + * Author: Joerg Roedel <joerg.roedel@amd.com> + */ + +#define pr_fmt(fmt) "DMA-API: " fmt + +#include <linux/sched/task_stack.h> +#include <linux/scatterlist.h> +#include <linux/dma-map-ops.h> +#include <linux/sched/task.h> +#include <linux/stacktrace.h> +#include <linux/spinlock.h> +#include <linux/vmalloc.h> +#include <linux/debugfs.h> +#include <linux/uaccess.h> +#include <linux/export.h> +#include <linux/device.h> +#include <linux/types.h> +#include <linux/sched.h> +#include <linux/ctype.h> +#include <linux/list.h> +#include <linux/slab.h> +#include <asm/sections.h> +#include "debug.h" + +#define HASH_SIZE 16384ULL +#define HASH_FN_SHIFT 13 +#define HASH_FN_MASK (HASH_SIZE - 1) + +#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16) +/* If the pool runs out, add this many new entries at once */ +#define DMA_DEBUG_DYNAMIC_ENTRIES (PAGE_SIZE / sizeof(struct dma_debug_entry)) + +enum { + dma_debug_single, + dma_debug_sg, + dma_debug_coherent, + dma_debug_resource, +}; + +enum map_err_types { + MAP_ERR_CHECK_NOT_APPLICABLE, + MAP_ERR_NOT_CHECKED, + MAP_ERR_CHECKED, +}; + +#define DMA_DEBUG_STACKTRACE_ENTRIES 5 + +/** + * struct dma_debug_entry - track a dma_map* or dma_alloc_coherent mapping + * @list: node on pre-allocated free_entries list + * @dev: 'dev' argument to dma_map_{page|single|sg} or dma_alloc_coherent + * @size: length of the mapping + * @type: single, page, sg, coherent + * @direction: enum dma_data_direction + * @sg_call_ents: 'nents' from dma_map_sg + * @sg_mapped_ents: 'mapped_ents' from dma_map_sg + * @pfn: page frame of the start address + * @offset: offset of mapping relative to pfn + * @map_err_type: track whether dma_mapping_error() was checked + * @stacktrace: support backtraces when a violation is detected + */ +struct dma_debug_entry { + struct list_head list; + struct device *dev; + u64 dev_addr; + u64 size; + int type; + int direction; + int sg_call_ents; + int sg_mapped_ents; + unsigned long pfn; + size_t offset; + enum map_err_types map_err_type; +#ifdef CONFIG_STACKTRACE + unsigned int stack_len; + unsigned long stack_entries[DMA_DEBUG_STACKTRACE_ENTRIES]; +#endif +} ____cacheline_aligned_in_smp; + +typedef bool (*match_fn)(struct dma_debug_entry *, struct dma_debug_entry *); + +struct hash_bucket { + struct list_head list; + spinlock_t lock; +}; + +/* Hash list to save the allocated dma addresses */ +static struct hash_bucket dma_entry_hash[HASH_SIZE]; +/* List of pre-allocated dma_debug_entry's */ +static LIST_HEAD(free_entries); +/* Lock for the list above */ +static DEFINE_SPINLOCK(free_entries_lock); + +/* Global disable flag - will be set in case of an error */ +static bool global_disable __read_mostly; + +/* Early initialization disable flag, set at the end of dma_debug_init */ +static bool dma_debug_initialized __read_mostly; + +static inline bool dma_debug_disabled(void) +{ + return global_disable || !dma_debug_initialized; +} + +/* Global error count */ +static u32 error_count; + +/* Global error show enable*/ +static u32 show_all_errors __read_mostly; +/* Number of errors to show */ +static u32 show_num_errors = 1; + +static u32 num_free_entries; +static u32 min_free_entries; +static u32 nr_total_entries; + +/* number of preallocated entries requested by kernel cmdline */ +static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES; + +/* per-driver filter related state */ + +#define NAME_MAX_LEN 64 + +static char current_driver_name[NAME_MAX_LEN] __read_mostly; +static struct device_driver *current_driver __read_mostly; + +static DEFINE_RWLOCK(driver_name_lock); + +static const char *const maperr2str[] = { + [MAP_ERR_CHECK_NOT_APPLICABLE] = "dma map error check not applicable", + [MAP_ERR_NOT_CHECKED] = "dma map error not checked", + [MAP_ERR_CHECKED] = "dma map error checked", +}; + +static const char *type2name[] = { + [dma_debug_single] = "single", + [dma_debug_sg] = "scather-gather", + [dma_debug_coherent] = "coherent", + [dma_debug_resource] = "resource", +}; + +static const char *dir2name[] = { + [DMA_BIDIRECTIONAL] = "DMA_BIDIRECTIONAL", + [DMA_TO_DEVICE] = "DMA_TO_DEVICE", + [DMA_FROM_DEVICE] = "DMA_FROM_DEVICE", + [DMA_NONE] = "DMA_NONE", +}; + +/* + * The access to some variables in this macro is racy. We can't use atomic_t + * here because all these variables are exported to debugfs. Some of them even + * writeable. This is also the reason why a lock won't help much. But anyway, + * the races are no big deal. Here is why: + * + * error_count: the addition is racy, but the worst thing that can happen is + * that we don't count some errors + * show_num_errors: the subtraction is racy. Also no big deal because in + * worst case this will result in one warning more in the + * system log than the user configured. This variable is + * writeable via debugfs. + */ +static inline void dump_entry_trace(struct dma_debug_entry *entry) +{ +#ifdef CONFIG_STACKTRACE + if (entry) { + pr_warn("Mapped at:\n"); + stack_trace_print(entry->stack_entries, entry->stack_len, 0); + } +#endif +} + +static bool driver_filter(struct device *dev) +{ + struct device_driver *drv; + unsigned long flags; + bool ret; + + /* driver filter off */ + if (likely(!current_driver_name[0])) + return true; + + /* driver filter on and initialized */ + if (current_driver && dev && dev->driver == current_driver) + return true; + + /* driver filter on, but we can't filter on a NULL device... */ + if (!dev) + return false; + + if (current_driver || !current_driver_name[0]) + return false; + + /* driver filter on but not yet initialized */ + drv = dev->driver; + if (!drv) + return false; + + /* lock to protect against change of current_driver_name */ + read_lock_irqsave(&driver_name_lock, flags); + + ret = false; + if (drv->name && + strncmp(current_driver_name, drv->name, NAME_MAX_LEN - 1) == 0) { + current_driver = drv; + ret = true; + } + + read_unlock_irqrestore(&driver_name_lock, flags); + + return ret; +} + +#define err_printk(dev, entry, format, arg...) do { \ + error_count += 1; \ + if (driver_filter(dev) && \ + (show_all_errors || show_num_errors > 0)) { \ + WARN(1, pr_fmt("%s %s: ") format, \ + dev ? dev_driver_string(dev) : "NULL", \ + dev ? dev_name(dev) : "NULL", ## arg); \ + dump_entry_trace(entry); \ + } \ + if (!show_all_errors && show_num_errors > 0) \ + show_num_errors -= 1; \ + } while (0); + +/* + * Hash related functions + * + * Every DMA-API request is saved into a struct dma_debug_entry. To + * have quick access to these structs they are stored into a hash. + */ +static int hash_fn(struct dma_debug_entry *entry) +{ + /* + * Hash function is based on the dma address. + * We use bits 20-27 here as the index into the hash + */ + return (entry->dev_addr >> HASH_FN_SHIFT) & HASH_FN_MASK; +} + +/* + * Request exclusive access to a hash bucket for a given dma_debug_entry. + */ +static struct hash_bucket *get_hash_bucket(struct dma_debug_entry *entry, + unsigned long *flags) + __acquires(&dma_entry_hash[idx].lock) +{ + int idx = hash_fn(entry); + unsigned long __flags; + + spin_lock_irqsave(&dma_entry_hash[idx].lock, __flags); + *flags = __flags; + return &dma_entry_hash[idx]; +} + +/* + * Give up exclusive access to the hash bucket + */ +static void put_hash_bucket(struct hash_bucket *bucket, + unsigned long flags) + __releases(&bucket->lock) +{ + spin_unlock_irqrestore(&bucket->lock, flags); +} + +static bool exact_match(struct dma_debug_entry *a, struct dma_debug_entry *b) +{ + return ((a->dev_addr == b->dev_addr) && + (a->dev == b->dev)) ? true : false; +} + +static bool containing_match(struct dma_debug_entry *a, + struct dma_debug_entry *b) +{ + if (a->dev != b->dev) + return false; + + if ((b->dev_addr <= a->dev_addr) && + ((b->dev_addr + b->size) >= (a->dev_addr + a->size))) + return true; + + return false; +} + +/* + * Search a given entry in the hash bucket list + */ +static struct dma_debug_entry *__hash_bucket_find(struct hash_bucket *bucket, + struct dma_debug_entry *ref, + match_fn match) +{ + struct dma_debug_entry *entry, *ret = NULL; + int matches = 0, match_lvl, last_lvl = -1; + + list_for_each_entry(entry, &bucket->list, list) { + if (!match(ref, entry)) + continue; + + /* + * Some drivers map the same physical address multiple + * times. Without a hardware IOMMU this results in the + * same device addresses being put into the dma-debug + * hash multiple times too. This can result in false + * positives being reported. Therefore we implement a + * best-fit algorithm here which returns the entry from + * the hash which fits best to the reference value + * instead of the first-fit. + */ + matches += 1; + match_lvl = 0; + entry->size == ref->size ? ++match_lvl : 0; + entry->type == ref->type ? ++match_lvl : 0; + entry->direction == ref->direction ? ++match_lvl : 0; + entry->sg_call_ents == ref->sg_call_ents ? ++match_lvl : 0; + + if (match_lvl == 4) { + /* perfect-fit - return the result */ + return entry; + } else if (match_lvl > last_lvl) { + /* + * We found an entry that fits better then the + * previous one or it is the 1st match. + */ + last_lvl = match_lvl; + ret = entry; + } + } + + /* + * If we have multiple matches but no perfect-fit, just return + * NULL. + */ + ret = (matches == 1) ? ret : NULL; + + return ret; +} + +static struct dma_debug_entry *bucket_find_exact(struct hash_bucket *bucket, + struct dma_debug_entry *ref) +{ + return __hash_bucket_find(bucket, ref, exact_match); +} + +static struct dma_debug_entry *bucket_find_contain(struct hash_bucket **bucket, + struct dma_debug_entry *ref, + unsigned long *flags) +{ + + struct dma_debug_entry *entry, index = *ref; + int limit = min(HASH_SIZE, (index.dev_addr >> HASH_FN_SHIFT) + 1); + + for (int i = 0; i < limit; i++) { + entry = __hash_bucket_find(*bucket, ref, containing_match); + + if (entry) + return entry; + + /* + * Nothing found, go back a hash bucket + */ + put_hash_bucket(*bucket, *flags); + index.dev_addr -= (1 << HASH_FN_SHIFT); + *bucket = get_hash_bucket(&index, flags); + } + + return NULL; +} + +/* + * Add an entry to a hash bucket + */ +static void hash_bucket_add(struct hash_bucket *bucket, + struct dma_debug_entry *entry) +{ + list_add_tail(&entry->list, &bucket->list); +} + +/* + * Remove entry from a hash bucket list + */ +static void hash_bucket_del(struct dma_debug_entry *entry) +{ + list_del(&entry->list); +} + +static unsigned long long phys_addr(struct dma_debug_entry *entry) +{ + if (entry->type == dma_debug_resource) + return __pfn_to_phys(entry->pfn) + entry->offset; + + return page_to_phys(pfn_to_page(entry->pfn)) + entry->offset; +} + +/* + * Dump mapping entries for debugging purposes + */ +void debug_dma_dump_mappings(struct device *dev) +{ + int idx; + + for (idx = 0; idx < HASH_SIZE; idx++) { + struct hash_bucket *bucket = &dma_entry_hash[idx]; + struct dma_debug_entry *entry; + unsigned long flags; + + spin_lock_irqsave(&bucket->lock, flags); + + list_for_each_entry(entry, &bucket->list, list) { + if (!dev || dev == entry->dev) { + dev_info(entry->dev, + "%s idx %d P=%Lx N=%lx D=%Lx L=%Lx %s %s\n", + type2name[entry->type], idx, + phys_addr(entry), entry->pfn, + entry->dev_addr, entry->size, + dir2name[entry->direction], + maperr2str[entry->map_err_type]); + } + } + + spin_unlock_irqrestore(&bucket->lock, flags); + cond_resched(); + } +} + +/* + * For each mapping (initial cacheline in the case of + * dma_alloc_coherent/dma_map_page, initial cacheline in each page of a + * scatterlist, or the cacheline specified in dma_map_single) insert + * into this tree using the cacheline as the key. At + * dma_unmap_{single|sg|page} or dma_free_coherent delete the entry. If + * the entry already exists at insertion time add a tag as a reference + * count for the overlapping mappings. For now, the overlap tracking + * just ensures that 'unmaps' balance 'maps' before marking the + * cacheline idle, but we should also be flagging overlaps as an API + * violation. + * + * Memory usage is mostly constrained by the maximum number of available + * dma-debug entries in that we need a free dma_debug_entry before + * inserting into the tree. In the case of dma_map_page and + * dma_alloc_coherent there is only one dma_debug_entry and one + * dma_active_cacheline entry to track per event. dma_map_sg(), on the + * other hand, consumes a single dma_debug_entry, but inserts 'nents' + * entries into the tree. + */ +static RADIX_TREE(dma_active_cacheline, GFP_ATOMIC); +static DEFINE_SPINLOCK(radix_lock); +#define ACTIVE_CACHELINE_MAX_OVERLAP ((1 << RADIX_TREE_MAX_TAGS) - 1) +#define CACHELINE_PER_PAGE_SHIFT (PAGE_SHIFT - L1_CACHE_SHIFT) +#define CACHELINES_PER_PAGE (1 << CACHELINE_PER_PAGE_SHIFT) + +static phys_addr_t to_cacheline_number(struct dma_debug_entry *entry) +{ + return (entry->pfn << CACHELINE_PER_PAGE_SHIFT) + + (entry->offset >> L1_CACHE_SHIFT); +} + +static int active_cacheline_read_overlap(phys_addr_t cln) +{ + int overlap = 0, i; + + for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--) + if (radix_tree_tag_get(&dma_active_cacheline, cln, i)) + overlap |= 1 << i; + return overlap; +} + +static int active_cacheline_set_overlap(phys_addr_t cln, int overlap) +{ + int i; + + if (overlap > ACTIVE_CACHELINE_MAX_OVERLAP || overlap < 0) + return overlap; + + for (i = RADIX_TREE_MAX_TAGS - 1; i >= 0; i--) + if (overlap & 1 << i) + radix_tree_tag_set(&dma_active_cacheline, cln, i); + else + radix_tree_tag_clear(&dma_active_cacheline, cln, i); + + return overlap; +} + +static void active_cacheline_inc_overlap(phys_addr_t cln) +{ + int overlap = active_cacheline_read_overlap(cln); + + overlap = active_cacheline_set_overlap(cln, ++overlap); + + /* If we overflowed the overlap counter then we're potentially + * leaking dma-mappings. + */ + WARN_ONCE(overlap > ACTIVE_CACHELINE_MAX_OVERLAP, + pr_fmt("exceeded %d overlapping mappings of cacheline %pa\n"), + ACTIVE_CACHELINE_MAX_OVERLAP, &cln); +} + +static int active_cacheline_dec_overlap(phys_addr_t cln) +{ + int overlap = active_cacheline_read_overlap(cln); + + return active_cacheline_set_overlap(cln, --overlap); +} + +static int active_cacheline_insert(struct dma_debug_entry *entry) +{ + phys_addr_t cln = to_cacheline_number(entry); + unsigned long flags; + int rc; + + /* If the device is not writing memory then we don't have any + * concerns about the cpu consuming stale data. This mitigates + * legitimate usages of overlapping mappings. + */ + if (entry->direction == DMA_TO_DEVICE) + return 0; + + spin_lock_irqsave(&radix_lock, flags); + rc = radix_tree_insert(&dma_active_cacheline, cln, entry); + if (rc == -EEXIST) + active_cacheline_inc_overlap(cln); + spin_unlock_irqrestore(&radix_lock, flags); + + return rc; +} + +static void active_cacheline_remove(struct dma_debug_entry *entry) +{ + phys_addr_t cln = to_cacheline_number(entry); + unsigned long flags; + + /* ...mirror the insert case */ + if (entry->direction == DMA_TO_DEVICE) + return; + + spin_lock_irqsave(&radix_lock, flags); + /* since we are counting overlaps the final put of the + * cacheline will occur when the overlap count is 0. + * active_cacheline_dec_overlap() returns -1 in that case + */ + if (active_cacheline_dec_overlap(cln) < 0) + radix_tree_delete(&dma_active_cacheline, cln); + spin_unlock_irqrestore(&radix_lock, flags); +} + +/* + * Wrapper function for adding an entry to the hash. + * This function takes care of locking itself. + */ +static void add_dma_entry(struct dma_debug_entry *entry, unsigned long attrs) +{ + struct hash_bucket *bucket; + unsigned long flags; + int rc; + + bucket = get_hash_bucket(entry, &flags); + hash_bucket_add(bucket, entry); + put_hash_bucket(bucket, flags); + + rc = active_cacheline_insert(entry); + if (rc == -ENOMEM) { + pr_err_once("cacheline tracking ENOMEM, dma-debug disabled\n"); + global_disable = true; + } else if (rc == -EEXIST && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)) { + err_printk(entry->dev, entry, + "cacheline tracking EEXIST, overlapping mappings aren't supported\n"); + } +} + +static int dma_debug_create_entries(gfp_t gfp) +{ + struct dma_debug_entry *entry; + int i; + + entry = (void *)get_zeroed_page(gfp); + if (!entry) + return -ENOMEM; + + for (i = 0; i < DMA_DEBUG_DYNAMIC_ENTRIES; i++) + list_add_tail(&entry[i].list, &free_entries); + + num_free_entries += DMA_DEBUG_DYNAMIC_ENTRIES; + nr_total_entries += DMA_DEBUG_DYNAMIC_ENTRIES; + + return 0; +} + +static struct dma_debug_entry *__dma_entry_alloc(void) +{ + struct dma_debug_entry *entry; + + entry = list_entry(free_entries.next, struct dma_debug_entry, list); + list_del(&entry->list); + memset(entry, 0, sizeof(*entry)); + + num_free_entries -= 1; + if (num_free_entries < min_free_entries) + min_free_entries = num_free_entries; + + return entry; +} + +/* + * This should be called outside of free_entries_lock scope to avoid potential + * deadlocks with serial consoles that use DMA. + */ +static void __dma_entry_alloc_check_leak(u32 nr_entries) +{ + u32 tmp = nr_entries % nr_prealloc_entries; + + /* Shout each time we tick over some multiple of the initial pool */ + if (tmp < DMA_DEBUG_DYNAMIC_ENTRIES) { + pr_info("dma_debug_entry pool grown to %u (%u00%%)\n", + nr_entries, + (nr_entries / nr_prealloc_entries)); + } +} + +/* struct dma_entry allocator + * + * The next two functions implement the allocator for + * struct dma_debug_entries. + */ +static struct dma_debug_entry *dma_entry_alloc(void) +{ + bool alloc_check_leak = false; + struct dma_debug_entry *entry; + unsigned long flags; + u32 nr_entries; + + spin_lock_irqsave(&free_entries_lock, flags); + if (num_free_entries == 0) { + if (dma_debug_create_entries(GFP_ATOMIC)) { + global_disable = true; + spin_unlock_irqrestore(&free_entries_lock, flags); + pr_err("debugging out of memory - disabling\n"); + return NULL; + } + alloc_check_leak = true; + nr_entries = nr_total_entries; + } + + entry = __dma_entry_alloc(); + + spin_unlock_irqrestore(&free_entries_lock, flags); + + if (alloc_check_leak) + __dma_entry_alloc_check_leak(nr_entries); + +#ifdef CONFIG_STACKTRACE + entry->stack_len = stack_trace_save(entry->stack_entries, + ARRAY_SIZE(entry->stack_entries), + 1); +#endif + return entry; +} + +static void dma_entry_free(struct dma_debug_entry *entry) +{ + unsigned long flags; + + active_cacheline_remove(entry); + + /* + * add to beginning of the list - this way the entries are + * more likely cache hot when they are reallocated. + */ + spin_lock_irqsave(&free_entries_lock, flags); + list_add(&entry->list, &free_entries); + num_free_entries += 1; + spin_unlock_irqrestore(&free_entries_lock, flags); +} + +/* + * DMA-API debugging init code + * + * The init code does two things: + * 1. Initialize core data structures + * 2. Preallocate a given number of dma_debug_entry structs + */ + +static ssize_t filter_read(struct file *file, char __user *user_buf, + size_t count, loff_t *ppos) +{ + char buf[NAME_MAX_LEN + 1]; + unsigned long flags; + int len; + + if (!current_driver_name[0]) + return 0; + + /* + * We can't copy to userspace directly because current_driver_name can + * only be read under the driver_name_lock with irqs disabled. So + * create a temporary copy first. + */ + read_lock_irqsave(&driver_name_lock, flags); + len = scnprintf(buf, NAME_MAX_LEN + 1, "%s\n", current_driver_name); + read_unlock_irqrestore(&driver_name_lock, flags); + + return simple_read_from_buffer(user_buf, count, ppos, buf, len); +} + +static ssize_t filter_write(struct file *file, const char __user *userbuf, + size_t count, loff_t *ppos) +{ + char buf[NAME_MAX_LEN]; + unsigned long flags; + size_t len; + int i; + + /* + * We can't copy from userspace directly. Access to + * current_driver_name is protected with a write_lock with irqs + * disabled. Since copy_from_user can fault and may sleep we + * need to copy to temporary buffer first + */ + len = min(count, (size_t)(NAME_MAX_LEN - 1)); + if (copy_from_user(buf, userbuf, len)) + return -EFAULT; + + buf[len] = 0; + + write_lock_irqsave(&driver_name_lock, flags); + + /* + * Now handle the string we got from userspace very carefully. + * The rules are: + * - only use the first token we got + * - token delimiter is everything looking like a space + * character (' ', '\n', '\t' ...) + * + */ + if (!isalnum(buf[0])) { + /* + * If the first character userspace gave us is not + * alphanumerical then assume the filter should be + * switched off. + */ + if (current_driver_name[0]) + pr_info("switching off dma-debug driver filter\n"); + current_driver_name[0] = 0; + current_driver = NULL; + goto out_unlock; + } + + /* + * Now parse out the first token and use it as the name for the + * driver to filter for. + */ + for (i = 0; i < NAME_MAX_LEN - 1; ++i) { + current_driver_name[i] = buf[i]; + if (isspace(buf[i]) || buf[i] == ' ' || buf[i] == 0) + break; + } + current_driver_name[i] = 0; + current_driver = NULL; + + pr_info("enable driver filter for driver [%s]\n", + current_driver_name); + +out_unlock: + write_unlock_irqrestore(&driver_name_lock, flags); + + return count; +} + +static const struct file_operations filter_fops = { + .read = filter_read, + .write = filter_write, + .llseek = default_llseek, +}; + +static int dump_show(struct seq_file *seq, void *v) +{ + int idx; + + for (idx = 0; idx < HASH_SIZE; idx++) { + struct hash_bucket *bucket = &dma_entry_hash[idx]; + struct dma_debug_entry *entry; + unsigned long flags; + + spin_lock_irqsave(&bucket->lock, flags); + list_for_each_entry(entry, &bucket->list, list) { + seq_printf(seq, + "%s %s %s idx %d P=%llx N=%lx D=%llx L=%llx %s %s\n", + dev_name(entry->dev), + dev_driver_string(entry->dev), + type2name[entry->type], idx, + phys_addr(entry), entry->pfn, + entry->dev_addr, entry->size, + dir2name[entry->direction], + maperr2str[entry->map_err_type]); + } + spin_unlock_irqrestore(&bucket->lock, flags); + } + return 0; +} +DEFINE_SHOW_ATTRIBUTE(dump); + +static int __init dma_debug_fs_init(void) +{ + struct dentry *dentry = debugfs_create_dir("dma-api", NULL); + + debugfs_create_bool("disabled", 0444, dentry, &global_disable); + debugfs_create_u32("error_count", 0444, dentry, &error_count); + debugfs_create_u32("all_errors", 0644, dentry, &show_all_errors); + debugfs_create_u32("num_errors", 0644, dentry, &show_num_errors); + debugfs_create_u32("num_free_entries", 0444, dentry, &num_free_entries); + debugfs_create_u32("min_free_entries", 0444, dentry, &min_free_entries); + debugfs_create_u32("nr_total_entries", 0444, dentry, &nr_total_entries); + debugfs_create_file("driver_filter", 0644, dentry, NULL, &filter_fops); + debugfs_create_file("dump", 0444, dentry, NULL, &dump_fops); + + return 0; +} +core_initcall_sync(dma_debug_fs_init); + +static int device_dma_allocations(struct device *dev, struct dma_debug_entry **out_entry) +{ + struct dma_debug_entry *entry; + unsigned long flags; + int count = 0, i; + + for (i = 0; i < HASH_SIZE; ++i) { + spin_lock_irqsave(&dma_entry_hash[i].lock, flags); + list_for_each_entry(entry, &dma_entry_hash[i].list, list) { + if (entry->dev == dev) { + count += 1; + *out_entry = entry; + } + } + spin_unlock_irqrestore(&dma_entry_hash[i].lock, flags); + } + + return count; +} + +static int dma_debug_device_change(struct notifier_block *nb, unsigned long action, void *data) +{ + struct device *dev = data; + struct dma_debug_entry *entry; + int count; + + if (dma_debug_disabled()) + return 0; + + switch (action) { + case BUS_NOTIFY_UNBOUND_DRIVER: + count = device_dma_allocations(dev, &entry); + if (count == 0) + break; + err_printk(dev, entry, "device driver has pending " + "DMA allocations while released from device " + "[count=%d]\n" + "One of leaked entries details: " + "[device address=0x%016llx] [size=%llu bytes] " + "[mapped with %s] [mapped as %s]\n", + count, entry->dev_addr, entry->size, + dir2name[entry->direction], type2name[entry->type]); + break; + default: + break; + } + + return 0; +} + +void dma_debug_add_bus(struct bus_type *bus) +{ + struct notifier_block *nb; + + if (dma_debug_disabled()) + return; + + nb = kzalloc(sizeof(struct notifier_block), GFP_KERNEL); + if (nb == NULL) { + pr_err("dma_debug_add_bus: out of memory\n"); + return; + } + + nb->notifier_call = dma_debug_device_change; + + bus_register_notifier(bus, nb); +} + +static int dma_debug_init(void) +{ + int i, nr_pages; + + /* Do not use dma_debug_initialized here, since we really want to be + * called to set dma_debug_initialized + */ + if (global_disable) + return 0; + + for (i = 0; i < HASH_SIZE; ++i) { + INIT_LIST_HEAD(&dma_entry_hash[i].list); + spin_lock_init(&dma_entry_hash[i].lock); + } + + nr_pages = DIV_ROUND_UP(nr_prealloc_entries, DMA_DEBUG_DYNAMIC_ENTRIES); + for (i = 0; i < nr_pages; ++i) + dma_debug_create_entries(GFP_KERNEL); + if (num_free_entries >= nr_prealloc_entries) { + pr_info("preallocated %d debug entries\n", nr_total_entries); + } else if (num_free_entries > 0) { + pr_warn("%d debug entries requested but only %d allocated\n", + nr_prealloc_entries, nr_total_entries); + } else { + pr_err("debugging out of memory error - disabled\n"); + global_disable = true; + + return 0; + } + min_free_entries = num_free_entries; + + dma_debug_initialized = true; + + pr_info("debugging enabled by kernel config\n"); + return 0; +} +core_initcall(dma_debug_init); + +static __init int dma_debug_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (strncmp(str, "off", 3) == 0) { + pr_info("debugging disabled on kernel command line\n"); + global_disable = true; + } + + return 1; +} + +static __init int dma_debug_entries_cmdline(char *str) +{ + if (!str) + return -EINVAL; + if (!get_option(&str, &nr_prealloc_entries)) + nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES; + return 1; +} + +__setup("dma_debug=", dma_debug_cmdline); +__setup("dma_debug_entries=", dma_debug_entries_cmdline); + +static void check_unmap(struct dma_debug_entry *ref) +{ + struct dma_debug_entry *entry; + struct hash_bucket *bucket; + unsigned long flags; + + bucket = get_hash_bucket(ref, &flags); + entry = bucket_find_exact(bucket, ref); + + if (!entry) { + /* must drop lock before calling dma_mapping_error */ + put_hash_bucket(bucket, flags); + + if (dma_mapping_error(ref->dev, ref->dev_addr)) { + err_printk(ref->dev, NULL, + "device driver tries to free an " + "invalid DMA memory address\n"); + } else { + err_printk(ref->dev, NULL, + "device driver tries to free DMA " + "memory it has not allocated [device " + "address=0x%016llx] [size=%llu bytes]\n", + ref->dev_addr, ref->size); + } + return; + } + + if (ref->size != entry->size) { + err_printk(ref->dev, entry, "device driver frees " + "DMA memory with different size " + "[device address=0x%016llx] [map size=%llu bytes] " + "[unmap size=%llu bytes]\n", + ref->dev_addr, entry->size, ref->size); + } + + if (ref->type != entry->type) { + err_printk(ref->dev, entry, "device driver frees " + "DMA memory with wrong function " + "[device address=0x%016llx] [size=%llu bytes] " + "[mapped as %s] [unmapped as %s]\n", + ref->dev_addr, ref->size, + type2name[entry->type], type2name[ref->type]); + } else if ((entry->type == dma_debug_coherent) && + (phys_addr(ref) != phys_addr(entry))) { + err_printk(ref->dev, entry, "device driver frees " + "DMA memory with different CPU address " + "[device address=0x%016llx] [size=%llu bytes] " + "[cpu alloc address=0x%016llx] " + "[cpu free address=0x%016llx]", + ref->dev_addr, ref->size, + phys_addr(entry), + phys_addr(ref)); + } + + if (ref->sg_call_ents && ref->type == dma_debug_sg && + ref->sg_call_ents != entry->sg_call_ents) { + err_printk(ref->dev, entry, "device driver frees " + "DMA sg list with different entry count " + "[map count=%d] [unmap count=%d]\n", + entry->sg_call_ents, ref->sg_call_ents); + } + + /* + * This may be no bug in reality - but most implementations of the + * DMA API don't handle this properly, so check for it here + */ + if (ref->direction != entry->direction) { + err_printk(ref->dev, entry, "device driver frees " + "DMA memory with different direction " + "[device address=0x%016llx] [size=%llu bytes] " + "[mapped with %s] [unmapped with %s]\n", + ref->dev_addr, ref->size, + dir2name[entry->direction], + dir2name[ref->direction]); + } + + /* + * Drivers should use dma_mapping_error() to check the returned + * addresses of dma_map_single() and dma_map_page(). + * If not, print this warning message. See Documentation/core-api/dma-api.rst. + */ + if (entry->map_err_type == MAP_ERR_NOT_CHECKED) { + err_printk(ref->dev, entry, + "device driver failed to check map error" + "[device address=0x%016llx] [size=%llu bytes] " + "[mapped as %s]", + ref->dev_addr, ref->size, + type2name[entry->type]); + } + + hash_bucket_del(entry); + dma_entry_free(entry); + + put_hash_bucket(bucket, flags); +} + +static void check_for_stack(struct device *dev, + struct page *page, size_t offset) +{ + void *addr; + struct vm_struct *stack_vm_area = task_stack_vm_area(current); + + if (!stack_vm_area) { + /* Stack is direct-mapped. */ + if (PageHighMem(page)) + return; + addr = page_address(page) + offset; + if (object_is_on_stack(addr)) + err_printk(dev, NULL, "device driver maps memory from stack [addr=%p]\n", addr); + } else { + /* Stack is vmalloced. */ + int i; + + for (i = 0; i < stack_vm_area->nr_pages; i++) { + if (page != stack_vm_area->pages[i]) + continue; + + addr = (u8 *)current->stack + i * PAGE_SIZE + offset; + err_printk(dev, NULL, "device driver maps memory from stack [probable addr=%p]\n", addr); + break; + } + } +} + +static void check_for_illegal_area(struct device *dev, void *addr, unsigned long len) +{ + if (memory_intersects(_stext, _etext, addr, len) || + memory_intersects(__start_rodata, __end_rodata, addr, len)) + err_printk(dev, NULL, "device driver maps memory from kernel text or rodata [addr=%p] [len=%lu]\n", addr, len); +} + +static void check_sync(struct device *dev, + struct dma_debug_entry *ref, + bool to_cpu) +{ + struct dma_debug_entry *entry; + struct hash_bucket *bucket; + unsigned long flags; + + bucket = get_hash_bucket(ref, &flags); + + entry = bucket_find_contain(&bucket, ref, &flags); + + if (!entry) { + err_printk(dev, NULL, "device driver tries " + "to sync DMA memory it has not allocated " + "[device address=0x%016llx] [size=%llu bytes]\n", + (unsigned long long)ref->dev_addr, ref->size); + goto out; + } + + if (ref->size > entry->size) { + err_printk(dev, entry, "device driver syncs" + " DMA memory outside allocated range " + "[device address=0x%016llx] " + "[allocation size=%llu bytes] " + "[sync offset+size=%llu]\n", + entry->dev_addr, entry->size, + ref->size); + } + + if (entry->direction == DMA_BIDIRECTIONAL) + goto out; + + if (ref->direction != entry->direction) { + err_printk(dev, entry, "device driver syncs " + "DMA memory with different direction " + "[device address=0x%016llx] [size=%llu bytes] " + "[mapped with %s] [synced with %s]\n", + (unsigned long long)ref->dev_addr, entry->size, + dir2name[entry->direction], + dir2name[ref->direction]); + } + + if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) && + !(ref->direction == DMA_TO_DEVICE)) + err_printk(dev, entry, "device driver syncs " + "device read-only DMA memory for cpu " + "[device address=0x%016llx] [size=%llu bytes] " + "[mapped with %s] [synced with %s]\n", + (unsigned long long)ref->dev_addr, entry->size, + dir2name[entry->direction], + dir2name[ref->direction]); + + if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) && + !(ref->direction == DMA_FROM_DEVICE)) + err_printk(dev, entry, "device driver syncs " + "device write-only DMA memory to device " + "[device address=0x%016llx] [size=%llu bytes] " + "[mapped with %s] [synced with %s]\n", + (unsigned long long)ref->dev_addr, entry->size, + dir2name[entry->direction], + dir2name[ref->direction]); + + if (ref->sg_call_ents && ref->type == dma_debug_sg && + ref->sg_call_ents != entry->sg_call_ents) { + err_printk(ref->dev, entry, "device driver syncs " + "DMA sg list with different entry count " + "[map count=%d] [sync count=%d]\n", + entry->sg_call_ents, ref->sg_call_ents); + } + +out: + put_hash_bucket(bucket, flags); +} + +static void check_sg_segment(struct device *dev, struct scatterlist *sg) +{ +#ifdef CONFIG_DMA_API_DEBUG_SG + unsigned int max_seg = dma_get_max_seg_size(dev); + u64 start, end, boundary = dma_get_seg_boundary(dev); + + /* + * Either the driver forgot to set dma_parms appropriately, or + * whoever generated the list forgot to check them. + */ + if (sg->length > max_seg) + err_printk(dev, NULL, "mapping sg segment longer than device claims to support [len=%u] [max=%u]\n", + sg->length, max_seg); + /* + * In some cases this could potentially be the DMA API + * implementation's fault, but it would usually imply that + * the scatterlist was built inappropriately to begin with. + */ + start = sg_dma_address(sg); + end = start + sg_dma_len(sg) - 1; + if ((start ^ end) & ~boundary) + err_printk(dev, NULL, "mapping sg segment across boundary [start=0x%016llx] [end=0x%016llx] [boundary=0x%016llx]\n", + start, end, boundary); +#endif +} + +void debug_dma_map_single(struct device *dev, const void *addr, + unsigned long len) +{ + if (unlikely(dma_debug_disabled())) + return; + + if (!virt_addr_valid(addr)) + err_printk(dev, NULL, "device driver maps memory from invalid area [addr=%p] [len=%lu]\n", + addr, len); + + if (is_vmalloc_addr(addr)) + err_printk(dev, NULL, "device driver maps memory from vmalloc area [addr=%p] [len=%lu]\n", + addr, len); +} +EXPORT_SYMBOL(debug_dma_map_single); + +void debug_dma_map_page(struct device *dev, struct page *page, size_t offset, + size_t size, int direction, dma_addr_t dma_addr, + unsigned long attrs) +{ + struct dma_debug_entry *entry; + + if (unlikely(dma_debug_disabled())) + return; + + if (dma_mapping_error(dev, dma_addr)) + return; + + entry = dma_entry_alloc(); + if (!entry) + return; + + entry->dev = dev; + entry->type = dma_debug_single; + entry->pfn = page_to_pfn(page); + entry->offset = offset; + entry->dev_addr = dma_addr; + entry->size = size; + entry->direction = direction; + entry->map_err_type = MAP_ERR_NOT_CHECKED; + + check_for_stack(dev, page, offset); + + if (!PageHighMem(page)) { + void *addr = page_address(page) + offset; + + check_for_illegal_area(dev, addr, size); + } + + add_dma_entry(entry, attrs); +} + +void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr) +{ + struct dma_debug_entry ref; + struct dma_debug_entry *entry; + struct hash_bucket *bucket; + unsigned long flags; + + if (unlikely(dma_debug_disabled())) + return; + + ref.dev = dev; + ref.dev_addr = dma_addr; + bucket = get_hash_bucket(&ref, &flags); + + list_for_each_entry(entry, &bucket->list, list) { + if (!exact_match(&ref, entry)) + continue; + + /* + * The same physical address can be mapped multiple + * times. Without a hardware IOMMU this results in the + * same device addresses being put into the dma-debug + * hash multiple times too. This can result in false + * positives being reported. Therefore we implement a + * best-fit algorithm here which updates the first entry + * from the hash which fits the reference value and is + * not currently listed as being checked. + */ + if (entry->map_err_type == MAP_ERR_NOT_CHECKED) { + entry->map_err_type = MAP_ERR_CHECKED; + break; + } + } + + put_hash_bucket(bucket, flags); +} +EXPORT_SYMBOL(debug_dma_mapping_error); + +void debug_dma_unmap_page(struct device *dev, dma_addr_t addr, + size_t size, int direction) +{ + struct dma_debug_entry ref = { + .type = dma_debug_single, + .dev = dev, + .dev_addr = addr, + .size = size, + .direction = direction, + }; + + if (unlikely(dma_debug_disabled())) + return; + check_unmap(&ref); +} + +void debug_dma_map_sg(struct device *dev, struct scatterlist *sg, + int nents, int mapped_ents, int direction, + unsigned long attrs) +{ + struct dma_debug_entry *entry; + struct scatterlist *s; + int i; + + if (unlikely(dma_debug_disabled())) + return; + + for_each_sg(sg, s, nents, i) { + check_for_stack(dev, sg_page(s), s->offset); + if (!PageHighMem(sg_page(s))) + check_for_illegal_area(dev, sg_virt(s), s->length); + } + + for_each_sg(sg, s, mapped_ents, i) { + entry = dma_entry_alloc(); + if (!entry) + return; + + entry->type = dma_debug_sg; + entry->dev = dev; + entry->pfn = page_to_pfn(sg_page(s)); + entry->offset = s->offset; + entry->size = sg_dma_len(s); + entry->dev_addr = sg_dma_address(s); + entry->direction = direction; + entry->sg_call_ents = nents; + entry->sg_mapped_ents = mapped_ents; + + check_sg_segment(dev, s); + + add_dma_entry(entry, attrs); + } +} + +static int get_nr_mapped_entries(struct device *dev, + struct dma_debug_entry *ref) +{ + struct dma_debug_entry *entry; + struct hash_bucket *bucket; + unsigned long flags; + int mapped_ents; + + bucket = get_hash_bucket(ref, &flags); + entry = bucket_find_exact(bucket, ref); + mapped_ents = 0; + + if (entry) + mapped_ents = entry->sg_mapped_ents; + put_hash_bucket(bucket, flags); + + return mapped_ents; +} + +void debug_dma_unmap_sg(struct device *dev, struct scatterlist *sglist, + int nelems, int dir) +{ + struct scatterlist *s; + int mapped_ents = 0, i; + + if (unlikely(dma_debug_disabled())) + return; + + for_each_sg(sglist, s, nelems, i) { + + struct dma_debug_entry ref = { + .type = dma_debug_sg, + .dev = dev, + .pfn = page_to_pfn(sg_page(s)), + .offset = s->offset, + .dev_addr = sg_dma_address(s), + .size = sg_dma_len(s), + .direction = dir, + .sg_call_ents = nelems, + }; + + if (mapped_ents && i >= mapped_ents) + break; + + if (!i) + mapped_ents = get_nr_mapped_entries(dev, &ref); + + check_unmap(&ref); + } +} + +void debug_dma_alloc_coherent(struct device *dev, size_t size, + dma_addr_t dma_addr, void *virt, + unsigned long attrs) +{ + struct dma_debug_entry *entry; + + if (unlikely(dma_debug_disabled())) + return; + + if (unlikely(virt == NULL)) + return; + + /* handle vmalloc and linear addresses */ + if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt)) + return; + + entry = dma_entry_alloc(); + if (!entry) + return; + + entry->type = dma_debug_coherent; + entry->dev = dev; + entry->offset = offset_in_page(virt); + entry->size = size; + entry->dev_addr = dma_addr; + entry->direction = DMA_BIDIRECTIONAL; + + if (is_vmalloc_addr(virt)) + entry->pfn = vmalloc_to_pfn(virt); + else + entry->pfn = page_to_pfn(virt_to_page(virt)); + + add_dma_entry(entry, attrs); +} + +void debug_dma_free_coherent(struct device *dev, size_t size, + void *virt, dma_addr_t addr) +{ + struct dma_debug_entry ref = { + .type = dma_debug_coherent, + .dev = dev, + .offset = offset_in_page(virt), + .dev_addr = addr, + .size = size, + .direction = DMA_BIDIRECTIONAL, + }; + + /* handle vmalloc and linear addresses */ + if (!is_vmalloc_addr(virt) && !virt_addr_valid(virt)) + return; + + if (is_vmalloc_addr(virt)) + ref.pfn = vmalloc_to_pfn(virt); + else + ref.pfn = page_to_pfn(virt_to_page(virt)); + + if (unlikely(dma_debug_disabled())) + return; + + check_unmap(&ref); +} + +void debug_dma_map_resource(struct device *dev, phys_addr_t addr, size_t size, + int direction, dma_addr_t dma_addr, + unsigned long attrs) +{ + struct dma_debug_entry *entry; + + if (unlikely(dma_debug_disabled())) + return; + + entry = dma_entry_alloc(); + if (!entry) + return; + + entry->type = dma_debug_resource; + entry->dev = dev; + entry->pfn = PHYS_PFN(addr); + entry->offset = offset_in_page(addr); + entry->size = size; + entry->dev_addr = dma_addr; + entry->direction = direction; + entry->map_err_type = MAP_ERR_NOT_CHECKED; + + add_dma_entry(entry, attrs); +} + +void debug_dma_unmap_resource(struct device *dev, dma_addr_t dma_addr, + size_t size, int direction) +{ + struct dma_debug_entry ref = { + .type = dma_debug_resource, + .dev = dev, + .dev_addr = dma_addr, + .size = size, + .direction = direction, + }; + + if (unlikely(dma_debug_disabled())) + return; + + check_unmap(&ref); +} + +void debug_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, + size_t size, int direction) +{ + struct dma_debug_entry ref; + + if (unlikely(dma_debug_disabled())) + return; + + ref.type = dma_debug_single; + ref.dev = dev; + ref.dev_addr = dma_handle; + ref.size = size; + ref.direction = direction; + ref.sg_call_ents = 0; + + check_sync(dev, &ref, true); +} + +void debug_dma_sync_single_for_device(struct device *dev, + dma_addr_t dma_handle, size_t size, + int direction) +{ + struct dma_debug_entry ref; + + if (unlikely(dma_debug_disabled())) + return; + + ref.type = dma_debug_single; + ref.dev = dev; + ref.dev_addr = dma_handle; + ref.size = size; + ref.direction = direction; + ref.sg_call_ents = 0; + + check_sync(dev, &ref, false); +} + +void debug_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, + int nelems, int direction) +{ + struct scatterlist *s; + int mapped_ents = 0, i; + + if (unlikely(dma_debug_disabled())) + return; + + for_each_sg(sg, s, nelems, i) { + + struct dma_debug_entry ref = { + .type = dma_debug_sg, + .dev = dev, + .pfn = page_to_pfn(sg_page(s)), + .offset = s->offset, + .dev_addr = sg_dma_address(s), + .size = sg_dma_len(s), + .direction = direction, + .sg_call_ents = nelems, + }; + + if (!i) + mapped_ents = get_nr_mapped_entries(dev, &ref); + + if (i >= mapped_ents) + break; + + check_sync(dev, &ref, true); + } +} + +void debug_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, + int nelems, int direction) +{ + struct scatterlist *s; + int mapped_ents = 0, i; + + if (unlikely(dma_debug_disabled())) + return; + + for_each_sg(sg, s, nelems, i) { + + struct dma_debug_entry ref = { + .type = dma_debug_sg, + .dev = dev, + .pfn = page_to_pfn(sg_page(s)), + .offset = s->offset, + .dev_addr = sg_dma_address(s), + .size = sg_dma_len(s), + .direction = direction, + .sg_call_ents = nelems, + }; + if (!i) + mapped_ents = get_nr_mapped_entries(dev, &ref); + + if (i >= mapped_ents) + break; + + check_sync(dev, &ref, false); + } +} + +static int __init dma_debug_driver_setup(char *str) +{ + int i; + + for (i = 0; i < NAME_MAX_LEN - 1; ++i, ++str) { + current_driver_name[i] = *str; + if (*str == 0) + break; + } + + if (current_driver_name[0]) + pr_info("enable driver filter for driver [%s]\n", + current_driver_name); + + + return 1; +} +__setup("dma_debug_driver=", dma_debug_driver_setup); |