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Subject[PATCH 08/16] dma-debug: add core checking functions
Date
Impact: add functions to check on dma unmap and sync

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
lib/dma-debug.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 147 insertions(+), 0 deletions(-)
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 1e16bd4..4d98811 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -17,9 +17,11 @@
* 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/list.h>
#include <linux/slab.h>
@@ -83,6 +85,36 @@ 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
*
@@ -378,3 +410,118 @@ 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,
+ entry->paddr, ref->paddr);
+ }
+
+ /*
+ * 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_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]);
+ }
+
+out:
+ put_hash_bucket(bucket, &flags);
+
+}
+
--
1.5.6.4



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