On Thu, 14 Jul 2022 12:08:02 +0300 Gwan-gyeong Mun <gwan-gyeong.mun@xxxxxxxxx> wrote: > From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > We need to check that we avoid integer overflows when looking up a page, > and so fix all the instances where we have mistakenly used a plain > integer instead of a more suitable long. Be pedantic and add integer > typechecking to the lookup so that we can be sure that we are safe. > And it also uses pgoff_t as our page lookups must remain compatible with > the page cache, pgoff_t is currently exactly unsigned long. > > v2: Move added i915_utils's macro into drm_util header (Jani N) > v3: Make not use the same macro name on a function. (Mauro) > For kernel-doc, macros and functions are handled in the same namespace, > the same macro name on a function prevents ever adding documentation > for it. > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@xxxxxxxxx> > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> > Cc: Matthew Auld <matthew.auld@xxxxxxxxx> > Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> > Reviewed-by: Nirmoy Das <nirmoy.das@xxxxxxxxx> LGTM, so: > Reviewed-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> Yet, it would make sense to have some patch adding kernel-doc markups to the kAPI functions declared at the header files here. Regards, Mauro > --- > drivers/gpu/drm/i915/gem/i915_gem_object.c | 7 +- > drivers/gpu/drm/i915/gem/i915_gem_object.h | 77 +++++++++++++------ > drivers/gpu/drm/i915/gem/i915_gem_pages.c | 27 ++++--- > drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 2 +- > .../drm/i915/gem/selftests/i915_gem_context.c | 12 +-- > .../drm/i915/gem/selftests/i915_gem_mman.c | 8 +- > .../drm/i915/gem/selftests/i915_gem_object.c | 8 +- > drivers/gpu/drm/i915/i915_gem.c | 18 ++++- > drivers/gpu/drm/i915/i915_vma.c | 8 +- > 9 files changed, 106 insertions(+), 61 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c > index ccec4055fde3..90996fe8ad45 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_object.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c > @@ -421,10 +421,11 @@ void __i915_gem_object_invalidate_frontbuffer(struct drm_i915_gem_object *obj, > static void > i915_gem_object_read_from_page_kmap(struct drm_i915_gem_object *obj, u64 offset, void *dst, int size) > { > + pgoff_t idx = offset >> PAGE_SHIFT; > void *src_map; > void *src_ptr; > > - src_map = kmap_atomic(i915_gem_object_get_page(obj, offset >> PAGE_SHIFT)); > + src_map = kmap_atomic(i915_gem_object_get_page(obj, idx)); > > src_ptr = src_map + offset_in_page(offset); > if (!(obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ)) > @@ -437,9 +438,10 @@ i915_gem_object_read_from_page_kmap(struct drm_i915_gem_object *obj, u64 offset, > static void > i915_gem_object_read_from_page_iomap(struct drm_i915_gem_object *obj, u64 offset, void *dst, int size) > { > + pgoff_t idx = offset >> PAGE_SHIFT; > + dma_addr_t dma = i915_gem_object_get_dma_address(obj, idx); > void __iomem *src_map; > void __iomem *src_ptr; > - dma_addr_t dma = i915_gem_object_get_dma_address(obj, offset >> PAGE_SHIFT); > > src_map = io_mapping_map_wc(&obj->mm.region->iomap, > dma - obj->mm.region->region.start, > @@ -468,6 +470,7 @@ i915_gem_object_read_from_page_iomap(struct drm_i915_gem_object *obj, u64 offset > */ > int i915_gem_object_read_from_page(struct drm_i915_gem_object *obj, u64 offset, void *dst, int size) > { > + GEM_BUG_ON(overflows_type(offset >> PAGE_SHIFT, pgoff_t)); > GEM_BUG_ON(offset >= obj->base.size); > GEM_BUG_ON(offset_in_page(offset) > PAGE_SIZE - size); > GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj)); > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h > index 6f0a3ce35567..4b49e0d2890b 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h > +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h > @@ -27,8 +27,10 @@ enum intel_region_id; > * spot such a local variable, please consider fixing! > * > * Aside from our own locals (for which we have no excuse!): > - * - sg_table embeds unsigned int for num_pages > - * - get_user_pages*() mixed ints with longs > + * - sg_table embeds unsigned int for nents > + * > + * We can check for invalidly typed locals with typecheck(), see for example > + * i915_gem_object_get_sg(). > */ > #define GEM_CHECK_SIZE_OVERFLOW(sz) \ > GEM_WARN_ON((sz) >> PAGE_SHIFT > INT_MAX) > @@ -364,43 +366,72 @@ int i915_gem_object_set_tiling(struct drm_i915_gem_object *obj, > unsigned int tiling, unsigned int stride); > > struct scatterlist * > -__i915_gem_object_get_sg(struct drm_i915_gem_object *obj, > - struct i915_gem_object_page_iter *iter, > - unsigned int n, > - unsigned int *offset, bool dma); > +__i915_gem_object_page_iter_get_sg(struct drm_i915_gem_object *obj, > + struct i915_gem_object_page_iter *iter, > + pgoff_t n, > + unsigned int *offset); > + > +#define i915_gem_object_page_iter_get_sg(obj, it, n, offset) ({ \ > + exactly_pgoff_t(n); \ > + __i915_gem_object_page_iter_get_sg(obj, it, n, offset); \ > +}) > > static inline struct scatterlist * > -i915_gem_object_get_sg(struct drm_i915_gem_object *obj, > - unsigned int n, > - unsigned int *offset) > +__i915_gem_object_get_sg(struct drm_i915_gem_object *obj, pgoff_t n, > + unsigned int *offset) > { > - return __i915_gem_object_get_sg(obj, &obj->mm.get_page, n, offset, false); > + return __i915_gem_object_page_iter_get_sg(obj, &obj->mm.get_page, n, offset); > } > > +#define i915_gem_object_get_sg(obj, n, offset) ({ \ > + exactly_pgoff_t(n); \ > + __i915_gem_object_get_sg(obj, n, offset); \ > +}) > + > static inline struct scatterlist * > -i915_gem_object_get_sg_dma(struct drm_i915_gem_object *obj, > - unsigned int n, > - unsigned int *offset) > +__i915_gem_object_get_sg_dma(struct drm_i915_gem_object *obj, pgoff_t n, > + unsigned int *offset) > { > - return __i915_gem_object_get_sg(obj, &obj->mm.get_dma_page, n, offset, true); > + return __i915_gem_object_page_iter_get_sg(obj, &obj->mm.get_dma_page, n, offset); > } > > +#define i915_gem_object_get_sg_dma(obj, n, offset) ({ \ > + exactly_pgoff_t(n); \ > + __i915_gem_object_get_sg_dma(obj, n, offset); \ > +}) > + > struct page * > -i915_gem_object_get_page(struct drm_i915_gem_object *obj, > - unsigned int n); > +__i915_gem_object_get_page(struct drm_i915_gem_object *obj, pgoff_t n); > + > +#define i915_gem_object_get_page(obj, n) ({ \ > + exactly_pgoff_t(n); \ > + __i915_gem_object_get_page(obj, n); \ > +}) > > struct page * > -i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, > - unsigned int n); > +__i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, pgoff_t n); > + > +#define i915_gem_object_get_dirty_page(obj, n) ({ \ > + exactly_pgoff_t(n); \ > + __i915_gem_object_get_dirty_page(obj, n); \ > +}) > > dma_addr_t > -i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj, > - unsigned long n, > - unsigned int *len); > +__i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj, pgoff_t n, > + unsigned int *len); > + > +#define i915_gem_object_get_dma_address_len(obj, n, len) ({ \ > + exactly_pgoff_t(n); \ > + __i915_gem_object_get_dma_address_len(obj, n, len); \ > +}) > > dma_addr_t > -i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, > - unsigned long n); > +__i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, pgoff_t n); > + > +#define i915_gem_object_get_dma_address(obj, n) ({ \ > + exactly_pgoff_t(n); \ > + __i915_gem_object_get_dma_address(obj, n); \ > +}) > > void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj, > struct sg_table *pages, > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c > index 97c820eee115..f994573cdcb1 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c > @@ -503,14 +503,16 @@ void __i915_gem_object_release_map(struct drm_i915_gem_object *obj) > } > > struct scatterlist * > -__i915_gem_object_get_sg(struct drm_i915_gem_object *obj, > - struct i915_gem_object_page_iter *iter, > - unsigned int n, > - unsigned int *offset, > - bool dma) > +__i915_gem_object_page_iter_get_sg(struct drm_i915_gem_object *obj, > + struct i915_gem_object_page_iter *iter, > + pgoff_t n, > + unsigned int *offset) > + > { > - struct scatterlist *sg; > + const bool dma = iter == &obj->mm.get_dma_page || > + iter == &obj->ttm.get_io_page; > unsigned int idx, count; > + struct scatterlist *sg; > > might_sleep(); > GEM_BUG_ON(n >= obj->base.size >> PAGE_SHIFT); > @@ -618,7 +620,7 @@ __i915_gem_object_get_sg(struct drm_i915_gem_object *obj, > } > > struct page * > -i915_gem_object_get_page(struct drm_i915_gem_object *obj, unsigned int n) > +__i915_gem_object_get_page(struct drm_i915_gem_object *obj, pgoff_t n) > { > struct scatterlist *sg; > unsigned int offset; > @@ -631,8 +633,7 @@ i915_gem_object_get_page(struct drm_i915_gem_object *obj, unsigned int n) > > /* Like i915_gem_object_get_page(), but mark the returned page dirty */ > struct page * > -i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, > - unsigned int n) > +__i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, pgoff_t n) > { > struct page *page; > > @@ -644,9 +645,8 @@ i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, > } > > dma_addr_t > -i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj, > - unsigned long n, > - unsigned int *len) > +__i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj, > + pgoff_t n, unsigned int *len) > { > struct scatterlist *sg; > unsigned int offset; > @@ -660,8 +660,7 @@ i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj, > } > > dma_addr_t > -i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, > - unsigned long n) > +__i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj, pgoff_t n) > { > return i915_gem_object_get_dma_address_len(obj, n, NULL); > } > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > index 5a5cf332d8a5..52c4c1fac7f9 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c > @@ -724,7 +724,7 @@ static unsigned long i915_ttm_io_mem_pfn(struct ttm_buffer_object *bo, > GEM_WARN_ON(bo->ttm); > > base = obj->mm.region->iomap.base - obj->mm.region->region.start; > - sg = __i915_gem_object_get_sg(obj, &obj->ttm.get_io_page, page_offset, &ofs, true); > + sg = i915_gem_object_page_iter_get_sg(obj, &obj->ttm.get_io_page, page_offset, &ofs); > > return ((base + sg_dma_address(sg)) >> PAGE_SHIFT) + ofs; > } > diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c > index c6ad67b90e8a..a18a890e681f 100644 > --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c > +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c > @@ -455,7 +455,8 @@ static int gpu_fill(struct intel_context *ce, > static int cpu_fill(struct drm_i915_gem_object *obj, u32 value) > { > const bool has_llc = HAS_LLC(to_i915(obj->base.dev)); > - unsigned int n, m, need_flush; > + unsigned int need_flush; > + unsigned long n, m; > int err; > > i915_gem_object_lock(obj, NULL); > @@ -485,7 +486,8 @@ static int cpu_fill(struct drm_i915_gem_object *obj, u32 value) > static noinline int cpu_check(struct drm_i915_gem_object *obj, > unsigned int idx, unsigned int max) > { > - unsigned int n, m, needs_flush; > + unsigned int needs_flush; > + unsigned long n; > int err; > > i915_gem_object_lock(obj, NULL); > @@ -494,7 +496,7 @@ static noinline int cpu_check(struct drm_i915_gem_object *obj, > goto out_unlock; > > for (n = 0; n < real_page_count(obj); n++) { > - u32 *map; > + u32 *map, m; > > map = kmap_atomic(i915_gem_object_get_page(obj, n)); > if (needs_flush & CLFLUSH_BEFORE) > @@ -502,7 +504,7 @@ static noinline int cpu_check(struct drm_i915_gem_object *obj, > > for (m = 0; m < max; m++) { > if (map[m] != m) { > - pr_err("%pS: Invalid value at object %d page %d/%ld, offset %d/%d: found %x expected %x\n", > + pr_err("%pS: Invalid value at object %d page %ld/%ld, offset %d/%d: found %x expected %x\n", > __builtin_return_address(0), idx, > n, real_page_count(obj), m, max, > map[m], m); > @@ -513,7 +515,7 @@ static noinline int cpu_check(struct drm_i915_gem_object *obj, > > for (; m < DW_PER_PAGE; m++) { > if (map[m] != STACK_MAGIC) { > - pr_err("%pS: Invalid value at object %d page %d, offset %d: found %x expected %x (uninitialised)\n", > + pr_err("%pS: Invalid value at object %d page %ld, offset %d: found %x expected %x (uninitialised)\n", > __builtin_return_address(0), idx, n, m, > map[m], STACK_MAGIC); > err = -EINVAL; > diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c > index 3ced9948a331..86e435d42546 100644 > --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c > +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c > @@ -95,11 +95,11 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj, > struct drm_i915_private *i915 = to_i915(obj->base.dev); > struct i915_ggtt_view view; > struct i915_vma *vma; > + unsigned long offset; > unsigned long page; > u32 __iomem *io; > struct page *p; > unsigned int n; > - u64 offset; > u32 *cpu; > int err; > > @@ -156,7 +156,7 @@ static int check_partial_mapping(struct drm_i915_gem_object *obj, > cpu = kmap(p) + offset_in_page(offset); > drm_clflush_virt_range(cpu, sizeof(*cpu)); > if (*cpu != (u32)page) { > - pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%llu + %u [0x%llx]) of 0x%x, found 0x%x\n", > + pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%lu + %u [0x%lx]) of 0x%x, found 0x%x\n", > page, n, > view.partial.offset, > view.partial.size, > @@ -212,10 +212,10 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj, > for_each_prime_number_from(page, 1, npages) { > struct i915_ggtt_view view = > compute_partial_view(obj, page, MIN_CHUNK_PAGES); > + unsigned long offset; > u32 __iomem *io; > struct page *p; > unsigned int n; > - u64 offset; > u32 *cpu; > > GEM_BUG_ON(view.partial.size > nreal); > @@ -252,7 +252,7 @@ static int check_partial_mappings(struct drm_i915_gem_object *obj, > cpu = kmap(p) + offset_in_page(offset); > drm_clflush_virt_range(cpu, sizeof(*cpu)); > if (*cpu != (u32)page) { > - pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%llu + %u [0x%llx]) of 0x%x, found 0x%x\n", > + pr_err("Partial view for %lu [%u] (offset=%llu, size=%u [%llu, row size %u], fence=%d, tiling=%d, stride=%d) misalignment, expected write to page (%lu + %u [0x%lx]) of 0x%x, found 0x%x\n", > page, n, > view.partial.offset, > view.partial.size, > diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_object.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_object.c > index fe0a890775e2..bf30763ee6bc 100644 > --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_object.c > +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_object.c > @@ -33,10 +33,10 @@ static int igt_gem_object(void *arg) > > static int igt_gem_huge(void *arg) > { > - const unsigned int nreal = 509; /* just to be awkward */ > + const unsigned long nreal = 509; /* just to be awkward */ > struct drm_i915_private *i915 = arg; > struct drm_i915_gem_object *obj; > - unsigned int n; > + unsigned long n; > int err; > > /* Basic sanitycheck of our huge fake object allocation */ > @@ -49,7 +49,7 @@ static int igt_gem_huge(void *arg) > > err = i915_gem_object_pin_pages_unlocked(obj); > if (err) { > - pr_err("Failed to allocate %u pages (%lu total), err=%d\n", > + pr_err("Failed to allocate %lu pages (%lu total), err=%d\n", > nreal, obj->base.size / PAGE_SIZE, err); > goto out; > } > @@ -57,7 +57,7 @@ static int igt_gem_huge(void *arg) > for (n = 0; n < obj->base.size / PAGE_SIZE; n++) { > if (i915_gem_object_get_page(obj, n) != > i915_gem_object_get_page(obj, n % nreal)) { > - pr_err("Page lookup mismatch at index %u [%u]\n", > + pr_err("Page lookup mismatch at index %lu [%lu]\n", > n, n % nreal); > err = -EINVAL; > goto out_unpin; > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 702e5b89be22..dba58a3c3238 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -229,8 +229,9 @@ i915_gem_shmem_pread(struct drm_i915_gem_object *obj, > struct drm_i915_gem_pread *args) > { > unsigned int needs_clflush; > - unsigned int idx, offset; > char __user *user_data; > + unsigned long offset; > + pgoff_t idx; > u64 remain; > int ret; > > @@ -383,13 +384,17 @@ i915_gem_gtt_pread(struct drm_i915_gem_object *obj, > { > struct drm_i915_private *i915 = to_i915(obj->base.dev); > struct i915_ggtt *ggtt = to_gt(i915)->ggtt; > + unsigned long remain, offset; > intel_wakeref_t wakeref; > struct drm_mm_node node; > void __user *user_data; > struct i915_vma *vma; > - u64 remain, offset; > int ret = 0; > > + if (overflows_type(args->size, remain) || > + overflows_type(args->offset, offset)) > + return -EINVAL; > + > wakeref = intel_runtime_pm_get(&i915->runtime_pm); > > vma = i915_gem_gtt_prepare(obj, &node, false); > @@ -540,13 +545,17 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj, > struct drm_i915_private *i915 = to_i915(obj->base.dev); > struct i915_ggtt *ggtt = to_gt(i915)->ggtt; > struct intel_runtime_pm *rpm = &i915->runtime_pm; > + unsigned long remain, offset; > intel_wakeref_t wakeref; > struct drm_mm_node node; > struct i915_vma *vma; > - u64 remain, offset; > void __user *user_data; > int ret = 0; > > + if (overflows_type(args->size, remain) || > + overflows_type(args->offset, offset)) > + return -EINVAL; > + > if (i915_gem_object_has_struct_page(obj)) { > /* > * Avoid waking the device up if we can fallback, as > @@ -654,8 +663,9 @@ i915_gem_shmem_pwrite(struct drm_i915_gem_object *obj, > { > unsigned int partial_cacheline_write; > unsigned int needs_clflush; > - unsigned int offset, idx; > void __user *user_data; > + unsigned long offset; > + pgoff_t idx; > u64 remain; > int ret; > > diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c > index ef3b04c7e153..28443c77b45a 100644 > --- a/drivers/gpu/drm/i915/i915_vma.c > +++ b/drivers/gpu/drm/i915/i915_vma.c > @@ -911,7 +911,7 @@ rotate_pages(struct drm_i915_gem_object *obj, unsigned int offset, > struct sg_table *st, struct scatterlist *sg) > { > unsigned int column, row; > - unsigned int src_idx; > + pgoff_t src_idx; > > for (column = 0; column < width; column++) { > unsigned int left; > @@ -1017,7 +1017,7 @@ add_padding_pages(unsigned int count, > > static struct scatterlist * > remap_tiled_color_plane_pages(struct drm_i915_gem_object *obj, > - unsigned int offset, unsigned int alignment_pad, > + unsigned long offset, unsigned int alignment_pad, > unsigned int width, unsigned int height, > unsigned int src_stride, unsigned int dst_stride, > struct sg_table *st, struct scatterlist *sg, > @@ -1076,7 +1076,7 @@ remap_tiled_color_plane_pages(struct drm_i915_gem_object *obj, > > static struct scatterlist * > remap_contiguous_pages(struct drm_i915_gem_object *obj, > - unsigned int obj_offset, > + pgoff_t obj_offset, > unsigned int count, > struct sg_table *st, struct scatterlist *sg) > { > @@ -1109,7 +1109,7 @@ remap_contiguous_pages(struct drm_i915_gem_object *obj, > > static struct scatterlist * > remap_linear_color_plane_pages(struct drm_i915_gem_object *obj, > - unsigned int obj_offset, unsigned int alignment_pad, > + pgoff_t obj_offset, unsigned int alignment_pad, > unsigned int size, > struct sg_table *st, struct scatterlist *sg, > unsigned int *gtt_offset)