From: Eric Anholt Date: Mon, 9 Mar 2009 20:42:30 +0000 (-0700) Subject: drm/i915: Fix lock order reversal in shmem pwrite path. X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=40123c1f8dd920dcff7a42cde5b351d7d0b0422e;p=openwrt%2Fstaging%2Fblogic.git drm/i915: Fix lock order reversal in shmem pwrite path. Like the GTT pwrite path fix, this uses an optimistic path and a fallback to get_user_pages. Note that this means we have to stop using vfs_write and roll it ourselves. Signed-off-by: Eric Anholt Reviewed-by: Jesse Barnes --- diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index b998d659fd98..bdc7326052df 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -136,6 +136,33 @@ i915_gem_create_ioctl(struct drm_device *dev, void *data, return 0; } +static inline int +slow_shmem_copy(struct page *dst_page, + int dst_offset, + struct page *src_page, + int src_offset, + int length) +{ + char *dst_vaddr, *src_vaddr; + + dst_vaddr = kmap_atomic(dst_page, KM_USER0); + if (dst_vaddr == NULL) + return -ENOMEM; + + src_vaddr = kmap_atomic(src_page, KM_USER1); + if (src_vaddr == NULL) { + kunmap_atomic(dst_vaddr, KM_USER0); + return -ENOMEM; + } + + memcpy(dst_vaddr + dst_offset, src_vaddr + src_offset, length); + + kunmap_atomic(src_vaddr, KM_USER1); + kunmap_atomic(dst_vaddr, KM_USER0); + + return 0; +} + /** * Reads data from the object referenced by handle. * @@ -243,6 +270,23 @@ slow_kernel_write(struct io_mapping *mapping, return 0; } +static inline int +fast_shmem_write(struct page **pages, + loff_t page_base, int page_offset, + char __user *data, + int length) +{ + char __iomem *vaddr; + + vaddr = kmap_atomic(pages[page_base >> PAGE_SHIFT], KM_USER0); + if (vaddr == NULL) + return -ENOMEM; + __copy_from_user_inatomic(vaddr + page_offset, data, length); + kunmap_atomic(vaddr, KM_USER0); + + return 0; +} + /** * This is the fast pwrite path, where we copy the data directly from the * user into the GTT, uncached. @@ -423,39 +467,175 @@ out_unpin_pages: return ret; } +/** + * This is the fast shmem pwrite path, which attempts to directly + * copy_from_user into the kmapped pages backing the object. + */ static int -i915_gem_shmem_pwrite(struct drm_device *dev, struct drm_gem_object *obj, - struct drm_i915_gem_pwrite *args, - struct drm_file *file_priv) +i915_gem_shmem_pwrite_fast(struct drm_device *dev, struct drm_gem_object *obj, + struct drm_i915_gem_pwrite *args, + struct drm_file *file_priv) { + struct drm_i915_gem_object *obj_priv = obj->driver_private; + ssize_t remain; + loff_t offset, page_base; + char __user *user_data; + int page_offset, page_length; int ret; - loff_t offset; - ssize_t written; + + user_data = (char __user *) (uintptr_t) args->data_ptr; + remain = args->size; mutex_lock(&dev->struct_mutex); + ret = i915_gem_object_get_pages(obj); + if (ret != 0) + goto fail_unlock; + ret = i915_gem_object_set_to_cpu_domain(obj, 1); - if (ret) { - mutex_unlock(&dev->struct_mutex); - return ret; + if (ret != 0) + goto fail_put_pages; + + obj_priv = obj->driver_private; + offset = args->offset; + obj_priv->dirty = 1; + + while (remain > 0) { + /* Operation in this page + * + * page_base = page offset within aperture + * page_offset = offset within page + * page_length = bytes to copy for this page + */ + page_base = (offset & ~(PAGE_SIZE-1)); + page_offset = offset & (PAGE_SIZE-1); + page_length = remain; + if ((page_offset + remain) > PAGE_SIZE) + page_length = PAGE_SIZE - page_offset; + + ret = fast_shmem_write(obj_priv->pages, + page_base, page_offset, + user_data, page_length); + if (ret) + goto fail_put_pages; + + remain -= page_length; + user_data += page_length; + offset += page_length; } +fail_put_pages: + i915_gem_object_put_pages(obj); +fail_unlock: + mutex_unlock(&dev->struct_mutex); + + return ret; +} + +/** + * This is the fallback shmem pwrite path, which uses get_user_pages to pin + * the memory and maps it using kmap_atomic for copying. + * + * This avoids taking mmap_sem for faulting on the user's address while the + * struct_mutex is held. + */ +static int +i915_gem_shmem_pwrite_slow(struct drm_device *dev, struct drm_gem_object *obj, + struct drm_i915_gem_pwrite *args, + struct drm_file *file_priv) +{ + struct drm_i915_gem_object *obj_priv = obj->driver_private; + struct mm_struct *mm = current->mm; + struct page **user_pages; + ssize_t remain; + loff_t offset, pinned_pages, i; + loff_t first_data_page, last_data_page, num_pages; + int shmem_page_index, shmem_page_offset; + int data_page_index, data_page_offset; + int page_length; + int ret; + uint64_t data_ptr = args->data_ptr; + + remain = args->size; + + /* Pin the user pages containing the data. We can't fault while + * holding the struct mutex, and all of the pwrite implementations + * want to hold it while dereferencing the user data. + */ + first_data_page = data_ptr / PAGE_SIZE; + last_data_page = (data_ptr + args->size - 1) / PAGE_SIZE; + num_pages = last_data_page - first_data_page + 1; + + user_pages = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL); + if (user_pages == NULL) + return -ENOMEM; + + down_read(&mm->mmap_sem); + pinned_pages = get_user_pages(current, mm, (uintptr_t)args->data_ptr, + num_pages, 0, 0, user_pages, NULL); + up_read(&mm->mmap_sem); + if (pinned_pages < num_pages) { + ret = -EFAULT; + goto fail_put_user_pages; + } + + mutex_lock(&dev->struct_mutex); + + ret = i915_gem_object_get_pages(obj); + if (ret != 0) + goto fail_unlock; + + ret = i915_gem_object_set_to_cpu_domain(obj, 1); + if (ret != 0) + goto fail_put_pages; + + obj_priv = obj->driver_private; offset = args->offset; + obj_priv->dirty = 1; - written = vfs_write(obj->filp, - (char __user *)(uintptr_t) args->data_ptr, - args->size, &offset); - if (written != args->size) { - mutex_unlock(&dev->struct_mutex); - if (written < 0) - return written; - else - return -EINVAL; + while (remain > 0) { + /* Operation in this page + * + * shmem_page_index = page number within shmem file + * shmem_page_offset = offset within page in shmem file + * data_page_index = page number in get_user_pages return + * data_page_offset = offset with data_page_index page. + * page_length = bytes to copy for this page + */ + shmem_page_index = offset / PAGE_SIZE; + shmem_page_offset = offset & ~PAGE_MASK; + data_page_index = data_ptr / PAGE_SIZE - first_data_page; + data_page_offset = data_ptr & ~PAGE_MASK; + + page_length = remain; + if ((shmem_page_offset + page_length) > PAGE_SIZE) + page_length = PAGE_SIZE - shmem_page_offset; + if ((data_page_offset + page_length) > PAGE_SIZE) + page_length = PAGE_SIZE - data_page_offset; + + ret = slow_shmem_copy(obj_priv->pages[shmem_page_index], + shmem_page_offset, + user_pages[data_page_index], + data_page_offset, + page_length); + if (ret) + goto fail_put_pages; + + remain -= page_length; + data_ptr += page_length; + offset += page_length; } +fail_put_pages: + i915_gem_object_put_pages(obj); +fail_unlock: mutex_unlock(&dev->struct_mutex); +fail_put_user_pages: + for (i = 0; i < pinned_pages; i++) + page_cache_release(user_pages[i]); + kfree(user_pages); - return 0; + return ret; } /** @@ -502,8 +682,13 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data, ret = i915_gem_gtt_pwrite_slow(dev, obj, args, file_priv); } - } else - ret = i915_gem_shmem_pwrite(dev, obj, args, file_priv); + } else { + ret = i915_gem_shmem_pwrite_fast(dev, obj, args, file_priv); + if (ret == -EFAULT) { + ret = i915_gem_shmem_pwrite_slow(dev, obj, args, + file_priv); + } + } #if WATCH_PWRITE if (ret)