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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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