// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2008 Advanced Micro Devices, Inc.
*
* Author: Joerg Roedel <[email protected]>
*/
#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
* @dev_addr: dma address
* @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
* @stack_len: number of backtrace entries in @stack_entries
* @stack_entries: stack of backtrace history
*/
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] = "scatter-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;
}
/*
* 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.
*
* Use __GFP_NOWARN because the printk from an OOM, to netconsole, could end
* up right back in the DMA debugging code, leading to a deadlock.
*/
static RADIX_TREE(dma_active_cacheline, GFP_ATOMIC | __GFP_NOWARN);
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);
}
/*
* Dump mappings entries on kernel space for debugging purposes
*/
void debug_dma_dump_mappings(struct device *dev)
{
int idx;
phys_addr_t cln;
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) {
cln = to_cacheline_number(entry);
dev_info(entry->dev,
"%s idx %d P=%llx N=%lx D=%llx L=%llx cln=%pa %s %s\n",
type2name[entry->type], idx,
phys_addr(entry), entry->pfn,
entry->dev_addr, entry->size,
&cln, dir2name[entry->direction],
maperr2str[entry->map_err_type]);
}
}
spin_unlock_irqrestore(&bucket->lock, flags);
cond_resched();
}
}
/*
* Dump mappings entries on user space via debugfs
*/
static int dump_show(struct seq_file *seq, void *v)
{
int idx;
phys_addr_t cln;
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) {
cln = to_cacheline_number(entry);
seq_printf(seq,
"%s %s %s idx %d P=%llx N=%lx D=%llx L=%llx cln=%pa %s %s\n",
dev_driver_string(entry->dev),
dev_name(entry->dev),
type2name[entry->type], idx,
phys_addr(entry), entry->pfn,
entry->dev_addr, entry->size,
&cln, dir2name[entry->direction],
maperr2str[entry->map_err_type]);
}
spin_unlock_irqrestore(&bucket->lock, flags);
}
return 0;
}
DEFINE_SHOW_ATTRIBUTE(dump);
/*
* 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 __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(const 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 dma_addr,
size_t size, int direction)
{
struct dma_debug_entry ref = {
.type = dma_debug_single,
.dev = dev,
.dev_addr = dma_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 dma_addr)
{
struct dma_debug_entry ref = {
.type = dma_debug_coherent,
.dev = dev,
.offset = offset_in_page(virt),
.dev_addr = dma_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);
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