On Thu, 2012-10-04 at 13:38 -0400, Konrad Rzeszutek Wilk wrote: > On Wed, Oct 03, 2012 at 08:55:59AM -0600, Shuah Khan wrote: > > A recent dma mapping error analysis effort showed that a large percentage > > of dma_map_single() and dma_map_page() returns are not checked for mapping > > errors. > > > > Reference: > > http://linuxdriverproject.org/mediawiki/index.php/DMA_Mapping_Error_Analysis > > > > Adding support for tracking dma mapping and unmapping errors to help assess > > the following: > > > > When do dma mapping errors get detected? > > How often do these errors occur? > > Why don't we see failures related to missing dma mapping error checks? > > Are they silent failures? > > > > Patch v3: Addresses review and design comments from Patch v2. > > Patch v2: Addressed design issues from Patch v1. > > > > Enhance dma-debug infrastructure to track dma mapping, and unmapping errors. > > > > map_errors: (system wide counter) > > Total number of dma mapping errors returned by the dma mapping interfaces, > > in response to mapping requests from all devices in the system. > > map_errors_not_checked: (system wide counter) > > Total number of dma mapping errors devices failed to check before using > > the returned address. > > unmap_errors: (system wide counter) > > Total number of times devices tried to unmap or free an invalid dma > > address. > > map_err_type: (new field added to dma_debug_entry structure) > > New field to maintain dma mapping error check status. This error type > > is applicable to the dma map page and dma map single entries tracked by > > dma-debug api. This status indicates whether or not a good mapping is > > checked by the device before its use. dma_map_single() and dma_map_page() > > could fail to create a mapping in some cases, and drivers are expected to > > call dma_mapping_error() to check for errors. Please note that this is not > > counter. > > > > Enhancements to dma-debug api are made to add new debugfs interfaces to > > report total dma errors, dma errors that are not checked, and unmap errors > > for the entire system. Please note that these are system wide counters for > > all devices in the system. > > > > The following new dma-debug interface is added: > > > > debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr) > > Sets dma map error checked status for the dma map entry if one is > > found. Decrements the system wide dma_map_errors_not_checked counter > > that is incremented by debug_dma_map_page() when it checks for > > mapping error before adding it to the dma debug entry table. > > > > New dma-debug internal interface: > > check_mapping_error(struct device *dev, dma_addr_t dma_addr) > > Calling dma_mapping_error() from dma-debug api will result in dma mapping > > check when it shouldn't. This internal routine checks dma mapping error > > without any debug checks. > > > > The following existing dma-debug api are changed to support this feature: > > debug_dma_map_page() > > Increments dma_map_errors and dma_map_errors_not_checked errors totals > > for the system, dma-debug api keeps track of, when dma_addr is invalid. > > This routine now calls internal check_mapping_error() interface to > > avoid doing dma mapping debug checks from dma-debug internal mapping > > error checks. > > check_unmap() > > This is an existing internal routines that checks for various mapping > > errors. Changed to increment system wide dma_unmap_errors, when a > > device requests an invalid address to be unmapped. This routine now > > calls internal check_mapping_error() interface to avoid doing dma > > mapping debug checks from dma-debug internal mapping error checks. > > > > Changed arch/x86/include/asm/dma-mapping.h to call debug_dma_mapping_error() > > to validate these new interfaces on x86_64. Other architectures will be > > changed in a subsequent patch. > > > > 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@xxxxxx> > > --- > > Documentation/DMA-API.txt | 13 ++++ > > arch/x86/include/asm/dma-mapping.h | 1 + > > include/linux/dma-debug.h | 7 ++ > > lib/dma-debug.c | 128 ++++++++++++++++++++++++++++++++---- > > 4 files changed, 136 insertions(+), 13 deletions(-) > > > > diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt > > index 66bd97a..886aaf9 100644 > > --- a/Documentation/DMA-API.txt > > +++ b/Documentation/DMA-API.txt > > @@ -638,6 +638,19 @@ this directory the following files can currently be found: > > dma-api/error_count This file is read-only and shows the total > > numbers of errors found. > > > > + dma-api/map_errors This file is read-only and shows the total > > + number of dma mapping errors detected. > > + > > + dma-api/map_errors_not_checked > > + This file is read-only and shows the total > > + number of dma mapping errors, device drivers > > + failed to check prior to using the returned > > + address. > > + > > + dma-api/unmap_errors > > + This file is read-only and shows the total > > + number of invalid dma unmapping attempts. > > + > > dma-api/num_errors The number in this file shows how many > > warnings will be printed to the kernel log > > before it stops. This number is initialized to > > diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h > > index f7b4c79..808dae6 100644 > > --- 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 171ad8a..fc0e34c 100644 > > --- 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 66ce414..1708a10 100644 > > --- a/lib/dma-debug.c > > +++ b/lib/dma-debug.c > > @@ -45,18 +45,25 @@ 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 { > > - struct list_head list; > > - struct device *dev; > > - int type; > > - phys_addr_t paddr; > > - u64 dev_addr; > > - u64 size; > > - int direction; > > - int sg_call_ents; > > - int sg_mapped_ents; > > + struct list_head list; > > + struct device *dev; > > + int type; > > + phys_addr_t paddr; > > + u64 dev_addr; > > + u64 size; > > + int direction; > > + int sg_call_ents; > > + int sg_mapped_ents; > > + enum map_err_types map_err_type; > > Something gone wild with your tabs/space. It should be only > one extra field added. I tabbed the existing fields over for readability. Guess I should have avoided the churn and left it alone. Will fix the tabs and send v4. > > Otherwise: > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Is it ok to add your reviewed by tag when I send v4? -- Shuah > > > #ifdef CONFIG_STACKTRACE > > struct stack_trace stacktrace; > > unsigned long st_entries[DMA_DEBUG_STACKTRACE_ENTRIES]; > > @@ -83,6 +90,11 @@ static u32 global_disable __read_mostly; > > /* Global error count */ > > static u32 error_count; > > > > +/* dma mapping error counts */ > > +static u32 map_errors; > > +static u32 map_errors_not_checked; > > +static u32 unmap_errors; > > + > > /* Global error show enable*/ > > static u32 show_all_errors __read_mostly; > > /* Number of errors to show */ > > @@ -104,6 +116,9 @@ 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 struct dentry *filter_dent __read_mostly; > > +static struct dentry *map_errors_dent __read_mostly; > > +static struct dentry *map_errors_not_checked_dent __read_mostly; > > +static struct dentry *unmap_errors_dent __read_mostly; > > > > /* per-driver filter related state */ > > > > @@ -114,6 +129,12 @@ 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" }; > > > > @@ -381,11 +402,12 @@ 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]); > > } > > } > > > > @@ -695,6 +717,28 @@ static int dma_debug_fs_init(void) > > if (!filter_dent) > > goto out_err; > > > > + map_errors_dent = debugfs_create_u32("map_errors", 0444, > > + dma_debug_dent, > > + &map_errors); > > + > > + if (!map_errors_dent) > > + goto out_err; > > + > > + map_errors_not_checked_dent = debugfs_create_u32( > > + "map_errors_not_checked", > > + 0444, > > + dma_debug_dent, > > + &map_errors_not_checked); > > + > > + if (!map_errors_not_checked_dent) > > + goto out_err; > > + > > + unmap_errors_dent = debugfs_create_u32("unmap_errors", 0444, > > + dma_debug_dent, > > + &unmap_errors); > > + if (!unmap_errors_dent) > > + goto out_err; > > + > > return 0; > > > > out_err: > > @@ -843,13 +887,29 @@ 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 check_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(check_mapping_error(ref->dev, ref->dev_addr))) { > > + unmap_errors += 1; > > err_printk(ref->dev, NULL, "DMA-API: device driver tries " > > "to free an invalid DMA memory address\n"); > > return; > > @@ -915,6 +975,15 @@ 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); > > > > @@ -1022,8 +1091,11 @@ 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(check_mapping_error(dev, dma_addr))) { > > + map_errors += 1; > > + map_errors_not_checked += 1; > > return; > > + } > > > > entry = dma_entry_alloc(); > > if (!entry) > > @@ -1035,6 +1107,7 @@ 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; > > @@ -1050,6 +1123,35 @@ 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) { > > + /* very likley dma-api didn't call debug_dma_map_page() or > > + debug_dma_map_page() detected mapping error */ > > + if (map_errors_not_checked) > > + map_errors_not_checked -= 1; > > + 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) > > { > > -- > > 1.7.9.5 > > > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ > > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
