dma-debug: new interfaces to debug dma mapping errors

Add dma-debug interface debug_dma_mapping_error() to debug drivers that
fail to check dma mapping errors on addresses returned by dma_map_single()
and dma_map_page() interfaces.  This interface clears a flag set by
debug_dma_map_page() to indicate that dma_mapping_error() has been called
by the driver.  When driver does unmap, debug_dma_unmap() checks the flag
and if this flag is still set, prints warning message that includes call
trace that leads up to the unmap.  This interface can be called from
dma_mapping_error() routines to enable dma mapping error check debugging.

Tested: Intel iommu and swiotlb (iommu=soft) on x86-64 with
        CONFIG_DMA_API_DEBUG enabled and disabled.

Signed-off-by: Shuah Khan <shuah.khan@hp.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 66bd97a95f10e18fc9b2a4bff7acb691957cc6a3..78a6c569d204bc0073e33fe093d34a8137e5eaf4 100644 (file)
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -678,3 +678,15 @@ out of dma_debug_entries. These entries are preallocated at boot. The number
 of preallocated entries is defined per architecture. If it is too low for you
 boot with 'dma_debug_entries=<your_desired_number>' to overwrite the
 architectural default.
+
+void debug_dmap_mapping_error(struct device *dev, dma_addr_t dma_addr);
+
+dma-debug interface debug_dma_mapping_error() to debug drivers that fail
+to check dma mapping errors on addresses returned by dma_map_single() and
+dma_map_page() interfaces. This interface clears a flag set by
+debug_dma_map_page() to indicate that dma_mapping_error() has been called by
+the driver. When driver does unmap, debug_dma_unmap() checks the flag and if
+this flag is still set, prints warning message that includes call trace that
+leads up to the unmap. This interface can be called from dma_mapping_error()
+routines to enable dma mapping error check debugging.
+

diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
index f7b4c7903e7e51eb317ecfcd6fa9be05a3336f65..808dae63eeea6f73eb312d4f5b7f77cf4e869e6c 100644 (file)
--- a/arch/x86/include/asm/dma-mapping.h
+++ b/arch/x86/include/asm/dma-mapping.h
@@ -47,6 +47,7 @@ static inline struct dma_map_ops *get_dma_ops(struct device *dev)
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
        struct dma_map_ops *ops = get_dma_ops(dev);
+       debug_dma_mapping_error(dev, dma_addr);
        if (ops->mapping_error)
                return ops->mapping_error(dev, dma_addr);
 

diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
index 171ad8aedc835258e152b94b2bc92242045d9c3e..fc0e34ce038f4055eaf7160cb1eb7693b7cc7e5d 100644 (file)
--- a/include/linux/dma-debug.h
+++ b/include/linux/dma-debug.h
@@ -39,6 +39,8 @@ extern void debug_dma_map_page(struct device *dev, struct page *page,
                               int direction, dma_addr_t dma_addr,
                               bool map_single);
 
+extern void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
+
 extern void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
                                 size_t size, int direction, bool map_single);
 
@@ -105,6 +107,11 @@ static inline void debug_dma_map_page(struct device *dev, struct page *page,
 {
 }
 
+static inline void debug_dma_mapping_error(struct device *dev,
+                                         dma_addr_t dma_addr)
+{
+}
+
 static inline void debug_dma_unmap_page(struct device *dev, dma_addr_t addr,
                                        size_t size, int direction,
                                        bool map_single)

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index d84beb994f36f1c0b6d7e82fa02fc558a13f88c9..59f4a1a8187d5201113684d671b785a3133ea62a 100644 (file)
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -45,6 +45,12 @@ enum {
        dma_debug_coherent,
 };
 
+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 {
@@ -57,6 +63,7 @@ struct dma_debug_entry {
        int              direction;
        int              sg_call_ents;
        int              sg_mapped_ents;
+       enum map_err_types  map_err_type;
 #ifdef CONFIG_STACKTRACE
        struct           stack_trace stacktrace;
        unsigned long    st_entries[DMA_DEBUG_STACKTRACE_ENTRIES];
@@ -114,6 +121,12 @@ 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[4] = { "single", "page",
                                    "scather-gather", "coherent" };
 
@@ -376,11 +389,12 @@ void debug_dma_dump_mappings(struct device *dev)
                list_for_each_entry(entry, &bucket->list, list) {
                        if (!dev || dev == entry->dev) {
                                dev_info(entry->dev,
-                                        "%s idx %d P=%Lx D=%Lx L=%Lx %s\n",
+                                        "%s idx %d P=%Lx D=%Lx L=%Lx %s %s\n",
                                         type2name[entry->type], idx,
                                         (unsigned long long)entry->paddr,
                                         entry->dev_addr, entry->size,
-                                        dir2name[entry->direction]);
+                                        dir2name[entry->direction],
+                                        maperr2str[entry->map_err_type]);
                        }
                }
 
@@ -838,13 +852,28 @@ static __init int dma_debug_entries_cmdline(char *str)
 __setup("dma_debug=", dma_debug_cmdline);
 __setup("dma_debug_entries=", dma_debug_entries_cmdline);
 
+/* Calling dma_mapping_error() from dma-debug api will result in calling
+   debug_dma_mapping_error() - need internal mapping error routine to
+   avoid debug checks */
+#ifndef DMA_ERROR_CODE
+#define DMA_ERROR_CODE 0
+#endif
+static inline int has_mapping_error(struct device *dev, dma_addr_t dma_addr)
+{
+       const struct dma_map_ops *ops = get_dma_ops(dev);
+       if (ops->mapping_error)
+               return ops->mapping_error(dev, dma_addr);
+
+       return (dma_addr == DMA_ERROR_CODE);
+}
+
 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)) {
+       if (unlikely(has_mapping_error(ref->dev, ref->dev_addr))) {
                err_printk(ref->dev, NULL, "DMA-API: device driver tries "
                           "to free an invalid DMA memory address\n");
                return;
@@ -910,6 +939,15 @@ static void check_unmap(struct dma_debug_entry *ref)
                           dir2name[ref->direction]);
        }
 
+       if (entry->map_err_type == MAP_ERR_NOT_CHECKED) {
+               err_printk(ref->dev, entry,
+                          "DMA-API: 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);
 
@@ -1017,7 +1055,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
        if (unlikely(global_disable))
                return;
 
-       if (unlikely(dma_mapping_error(dev, dma_addr)))
+       if (unlikely(has_mapping_error(dev, dma_addr)))
                return;
 
        entry = dma_entry_alloc();
@@ -1030,6 +1068,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
        entry->dev_addr  = dma_addr;
        entry->size      = size;
        entry->direction = direction;
+       entry->map_err_type = MAP_ERR_NOT_CHECKED;
 
        if (map_single)
                entry->type = dma_debug_single;
@@ -1045,6 +1084,30 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
 }
 EXPORT_SYMBOL(debug_dma_map_page);
 
+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(global_disable))
+               return;
+
+       ref.dev = dev;
+       ref.dev_addr = dma_addr;
+       bucket = get_hash_bucket(&ref, &flags);
+       entry = bucket_find_exact(bucket, &ref);
+
+       if (!entry)
+               goto out;
+
+       entry->map_err_type = MAP_ERR_CHECKED;
+out:
+       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, bool map_single)
 {