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Commit 6c9c6d63 authored by Shuah Khan's avatar Shuah Khan Committed by Joerg Roedel
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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: default avatarShuah Khan <shuah.khan@hp.com>
Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent 6f0c0580

Documentation/DMA-API.txt

+12 −0
Original line number Diff line number Diff line
@@ -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.

arch/x86/include/asm/dma-mapping.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

include/linux/dma-debug.h

+7 −0
Original line number Diff line number Diff line
@@ -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)

lib/dma-debug.c

+67 −4
Original line number Diff line number Diff line
@@ -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)

{