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dma-debug: add core checking functions
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Impact: add functions to check on dma unmap and sync

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
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Joerg Roedel committed Mar 5, 2009
1 parent 788dcfa commit 2d62ece
Showing 1 changed file with 187 additions and 1 deletion.
188 changes: 187 additions & 1 deletion lib/dma-debug.c
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Original file line number Diff line number Diff line change
Expand Up @@ -17,10 +17,13 @@
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/

#include <linux/dma-mapping.h>
#include <linux/dma-debug.h>
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/slab.h>

Expand Down Expand Up @@ -50,7 +53,7 @@ struct dma_debug_entry {
struct hash_bucket {
struct list_head list;
spinlock_t lock;
} __cacheline_aligned_in_smp;
} ____cacheline_aligned_in_smp;

/* Hash list to save the allocated dma addresses */
static struct hash_bucket dma_entry_hash[HASH_SIZE];
Expand Down Expand Up @@ -85,6 +88,36 @@ static struct dentry *show_num_errors_dent __read_mostly;
static struct dentry *num_free_entries_dent __read_mostly;
static struct dentry *min_free_entries_dent __read_mostly;

static const char *type2name[4] = { "single", "page",
"scather-gather", "coherent" };

static const char *dir2name[4] = { "DMA_BIDIRECTIONAL", "DMA_TO_DEVICE",
"DMA_FROM_DEVICE", "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.
*/
#define err_printk(dev, format, arg...) do { \
error_count += 1; \
if (show_all_errors || show_num_errors > 0) { \
WARN(1, "%s %s: " format, \
dev_driver_string(dev), \
dev_name(dev) , ## arg); \
} \
if (!show_all_errors && show_num_errors > 0) \
show_num_errors -= 1; \
} while (0);

/*
* Hash related functions
*
Expand Down Expand Up @@ -380,3 +413,156 @@ static __init int dma_debug_entries_cmdline(char *str)
__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;

if (dma_mapping_error(ref->dev, ref->dev_addr))
return;

bucket = get_hash_bucket(ref, &flags);
entry = hash_bucket_find(bucket, ref);

if (!entry) {
err_printk(ref->dev, "DMA-API: device driver tries "
"to free DMA memory it has not allocated "
"[device address=0x%016llx] [size=%llu bytes]\n",
ref->dev_addr, ref->size);
goto out;
}

if (ref->size != entry->size) {
err_printk(ref->dev, "DMA-API: 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, "DMA-API: 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) &&
(ref->paddr != entry->paddr)) {
err_printk(ref->dev, "DMA-API: device driver frees "
"DMA memory with different CPU address "
"[device address=0x%016llx] [size=%llu bytes] "
"[cpu alloc address=%p] [cpu free address=%p]",
ref->dev_addr, ref->size,
(void *)entry->paddr, (void *)ref->paddr);
}

if (ref->sg_call_ents && ref->type == dma_debug_sg &&
ref->sg_call_ents != entry->sg_call_ents) {
err_printk(ref->dev, "DMA-API: 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, "DMA-API: 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]);
}

hash_bucket_del(entry);
dma_entry_free(entry);

out:
put_hash_bucket(bucket, &flags);
}

static void check_for_stack(struct device *dev, void *addr)
{
if (object_is_on_stack(addr))
err_printk(dev, "DMA-API: device driver maps memory from stack"
" [addr=%p]\n", addr);
}

static void check_sync(struct device *dev, dma_addr_t addr,
u64 size, u64 offset, int direction, bool to_cpu)
{
struct dma_debug_entry ref = {
.dev = dev,
.dev_addr = addr,
.size = size,
.direction = direction,
};
struct dma_debug_entry *entry;
struct hash_bucket *bucket;
unsigned long flags;

bucket = get_hash_bucket(&ref, &flags);

entry = hash_bucket_find(bucket, &ref);

if (!entry) {
err_printk(dev, "DMA-API: device driver tries "
"to sync DMA memory it has not allocated "
"[device address=0x%016llx] [size=%llu bytes]\n",
addr, size);
goto out;
}

if ((offset + size) > entry->size) {
err_printk(dev, "DMA-API: device driver syncs"
" DMA memory outside allocated range "
"[device address=0x%016llx] "
"[allocation size=%llu bytes] [sync offset=%llu] "
"[sync size=%llu]\n", entry->dev_addr, entry->size,
offset, size);
}

if (direction != entry->direction) {
err_printk(dev, "DMA-API: device driver syncs "
"DMA memory with different direction "
"[device address=0x%016llx] [size=%llu bytes] "
"[mapped with %s] [synced with %s]\n",
addr, entry->size,
dir2name[entry->direction],
dir2name[direction]);
}

if (entry->direction == DMA_BIDIRECTIONAL)
goto out;

if (to_cpu && !(entry->direction == DMA_FROM_DEVICE) &&
!(direction == DMA_TO_DEVICE))
err_printk(dev, "DMA-API: device driver syncs "
"device read-only DMA memory for cpu "
"[device address=0x%016llx] [size=%llu bytes] "
"[mapped with %s] [synced with %s]\n",
addr, entry->size,
dir2name[entry->direction],
dir2name[direction]);

if (!to_cpu && !(entry->direction == DMA_TO_DEVICE) &&
!(direction == DMA_FROM_DEVICE))
err_printk(dev, "DMA-API: device driver syncs "
"device write-only DMA memory to device "
"[device address=0x%016llx] [size=%llu bytes] "
"[mapped with %s] [synced with %s]\n",
addr, entry->size,
dir2name[entry->direction],
dir2name[direction]);

out:
put_hash_bucket(bucket, &flags);

}

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