1 files changed, 43 insertions, 22 deletions

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 7f5cdc1e6b29..c007d25bee09 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -41,6 +41,11 @@
 #define HASH_FN_SHIFT   13
 #define HASH_FN_MASK    (HASH_SIZE - 1)
 
+/* allow architectures to override this if absolutely required */
+#ifndef PREALLOC_DMA_DEBUG_ENTRIES
+#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
+#endif
+
 enum {
         dma_debug_single,
         dma_debug_page,
@@ -127,7 +132,7 @@ static u32 min_free_entries;
 static u32 nr_total_entries;
 
 /* number of preallocated entries requested by kernel cmdline */
-static u32 req_entries;
+static u32 nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
 
 /* debugfs dentry's for the stuff above */
 static struct dentry *dma_debug_dent        __read_mostly;
@@ -439,7 +444,6 @@ void debug_dma_dump_mappings(struct device *dev)
                 spin_unlock_irqrestore(&bucket->lock, flags);
         }
 }
-EXPORT_SYMBOL(debug_dma_dump_mappings);
 
 /*
  * For each mapping (initial cacheline in the case of
@@ -748,7 +752,6 @@ int dma_debug_resize_entries(u32 num_entries)
 
         return ret;
 }
-EXPORT_SYMBOL(dma_debug_resize_entries);
 
 /*
  * DMA-API debugging init code
@@ -1004,10 +1007,7 @@ void dma_debug_add_bus(struct bus_type *bus)
         bus_register_notifier(bus, nb);
 }
 
-/*
- * Let the architectures decide how many entries should be preallocated.
- */
-void dma_debug_init(u32 num_entries)
+static int dma_debug_init(void)
 {
         int i;
 
@@ -1015,7 +1015,7 @@ void dma_debug_init(u32 num_entries)
          * called to set dma_debug_initialized
          */
         if (global_disable)
-                return;
+                return 0;
 
         for (i = 0; i < HASH_SIZE; ++i) {
                 INIT_LIST_HEAD(&dma_entry_hash[i].list);
@@ -1026,17 +1026,14 @@ void dma_debug_init(u32 num_entries)
                 pr_err("DMA-API: error creating debugfs entries - disabling\n");
                 global_disable = true;
 
-                return;
+                return 0;
         }
 
-        if (req_entries)
-                num_entries = req_entries;
-
-        if (prealloc_memory(num_entries) != 0) {
+        if (prealloc_memory(nr_prealloc_entries) != 0) {
                 pr_err("DMA-API: debugging out of memory error - disabled\n");
                 global_disable = true;
 
-                return;
+                return 0;
         }
 
         nr_total_entries = num_free_entries;
@@ -1044,7 +1041,9 @@ void dma_debug_init(u32 num_entries)
         dma_debug_initialized = true;
 
         pr_info("DMA-API: debugging enabled by kernel config\n");
+        return 0;
 }
+core_initcall(dma_debug_init);
 
 static __init int dma_debug_cmdline(char *str)
 {
@@ -1061,16 +1060,10 @@ static __init int dma_debug_cmdline(char *str)
 
 static __init int dma_debug_entries_cmdline(char *str)
 {
-        int res;
-
         if (!str)
                 return -EINVAL;
-
-        res = get_option(&str, &req_entries);
-
-        if (!res)
-                req_entries = 0;
-
+        if (!get_option(&str, &nr_prealloc_entries))
+                nr_prealloc_entries = PREALLOC_DMA_DEBUG_ENTRIES;
         return 0;
 }
 
@@ -1293,6 +1286,32 @@ 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, "DMA-API: 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, "DMA-API: mapping sg segment across boundary [start=0x%016llx] [end=0x%016llx] [boundary=0x%016llx]\n",
+                           start, end, boundary);
+#endif
+}
+
 void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
                         size_t size, int direction, dma_addr_t dma_addr,
                         bool map_single)
@@ -1423,6 +1442,8 @@ void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
                 }
 
+                check_sg_segment(dev, s);
+
                 add_dma_entry(entry);
         }
 }