1 files changed, 69 insertions, 126 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 8f1633c3fb93..26dda55a07ff 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -1,12 +1,12 @@
+// SPDX-License-Identifier: MIT
 /*
- * SPDX-License-Identifier: MIT
- *
  * Copyright © 2014-2016 Intel Corporation
  */
 
 #include <linux/pagevec.h>
 #include <linux/shmem_fs.h>
 #include <linux/swap.h>
+#include <linux/uio.h>
 
 #include <drm/drm_cache.h>
 
@@ -100,6 +100,7 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
 	st->nents = 0;
 	for (i = 0; i < page_count; i++) {
 		struct folio *folio;
+		unsigned long nr_pages;
 		const unsigned int shrink[] = {
 			I915_SHRINK_BOUND | I915_SHRINK_UNBOUND,
 			0,
@@ -150,6 +151,8 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
 			}
 		} while (1);
 
+		nr_pages = min_t(unsigned long,
+				folio_nr_pages(folio), page_count - i);
 		if (!i ||
 		    sg->length >= max_segment ||
 		    folio_pfn(folio) != next_pfn) {
@@ -157,13 +160,13 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
 				sg = sg_next(sg);
 
 			st->nents++;
-			sg_set_folio(sg, folio, folio_size(folio), 0);
+			sg_set_folio(sg, folio, nr_pages * PAGE_SIZE, 0);
 		} else {
 			/* XXX: could overflow? */
-			sg->length += folio_size(folio);
+			sg->length += nr_pages * PAGE_SIZE;
 		}
-		next_pfn = folio_pfn(folio) + folio_nr_pages(folio);
-		i += folio_nr_pages(folio) - 1;
+		next_pfn = folio_pfn(folio) + nr_pages;
+		i += nr_pages - 1;
 
 		/* Check that the i965g/gm workaround works. */
 		GEM_BUG_ON(gfp & __GFP_DMA32 && next_pfn >= 0x00100000UL);
@@ -206,8 +209,6 @@ static int shmem_get_pages(struct drm_i915_gem_object *obj)
 	struct address_space *mapping = obj->base.filp->f_mapping;
 	unsigned int max_segment = i915_sg_segment_size(i915->drm.dev);
 	struct sg_table *st;
-	struct sgt_iter sgt_iter;
-	struct page *page;
 	int ret;
 
 	/*
@@ -236,9 +237,7 @@ rebuild_st:
 		 * for PAGE_SIZE chunks instead may be helpful.
 		 */
 		if (max_segment > PAGE_SIZE) {
-			for_each_sgt_page(page, sgt_iter, st)
-				put_page(page);
-			sg_free_table(st);
+			shmem_sg_free_table(st, mapping, false, false);
 			kfree(st);
 
 			max_segment = PAGE_SIZE;
@@ -304,38 +303,21 @@ void __shmem_writeback(size_t size, struct address_space *mapping)
 		.nr_to_write = SWAP_CLUSTER_MAX,
 		.range_start = 0,
 		.range_end = LLONG_MAX,
-		.for_reclaim = 1,
 	};
-	unsigned long i;
+	struct folio *folio = NULL;
+	int error = 0;
 
 	/*
 	 * Leave mmapings intact (GTT will have been revoked on unbinding,
-	 * leaving only CPU mmapings around) and add those pages to the LRU
+	 * leaving only CPU mmapings around) and add those folios to the LRU
 	 * instead of invoking writeback so they are aged and paged out
 	 * as normal.
 	 */
-
-	/* Begin writeback on each dirty page */
-	for (i = 0; i < size >> PAGE_SHIFT; i++) {
-		struct page *page;
-
-		page = find_lock_page(mapping, i);
-		if (!page)
-			continue;
-
-		if (!page_mapped(page) && clear_page_dirty_for_io(page)) {
-			int ret;
-
-			SetPageReclaim(page);
-			ret = mapping->a_ops->writepage(page, &wbc);
-			if (!PageWriteback(page))
-				ClearPageReclaim(page);
-			if (!ret)
-				goto put;
-		}
-		unlock_page(page);
-put:
-		put_page(page);
+	while ((folio = writeback_iter(mapping, &wbc, folio, &error))) {
+		if (folio_mapped(folio))
+			folio_redirty_for_writepage(&wbc, folio);
+		else
+			error = shmem_writeout(folio, NULL, NULL);
 	}
 }
 
@@ -418,11 +400,12 @@ static int
 shmem_pwrite(struct drm_i915_gem_object *obj,
 	     const struct drm_i915_gem_pwrite *arg)
 {
-	struct address_space *mapping = obj->base.filp->f_mapping;
-	const struct address_space_operations *aops = mapping->a_ops;
 	char __user *user_data = u64_to_user_ptr(arg->data_ptr);
-	u64 remain, offset;
-	unsigned int pg;
+	struct file *file = obj->base.filp;
+	struct kiocb kiocb;
+	struct iov_iter iter;
+	ssize_t written;
+	u64 size = arg->size;
 
 	/* Caller already validated user args */
 	GEM_BUG_ON(!access_ok(user_data, arg->size));
@@ -445,63 +428,33 @@ shmem_pwrite(struct drm_i915_gem_object *obj,
 	if (obj->mm.madv != I915_MADV_WILLNEED)
 		return -EFAULT;
 
+	if (size > MAX_RW_COUNT)
+		return -EFBIG;
+
+	if (!file->f_op->write_iter)
+		return -EINVAL;
+
+	init_sync_kiocb(&kiocb, file);
+	kiocb.ki_pos = arg->offset;
+	iov_iter_ubuf(&iter, ITER_SOURCE, (void __user *)user_data, size);
+
+	written = file->f_op->write_iter(&kiocb, &iter);
+	BUG_ON(written == -EIOCBQUEUED);
+
 	/*
-	 * Before the pages are instantiated the object is treated as being
-	 * in the CPU domain. The pages will be clflushed as required before
-	 * use, and we can freely write into the pages directly. If userspace
-	 * races pwrite with any other operation; corruption will ensue -
-	 * that is userspace's prerogative!
+	 * First, check if write_iter returned a negative error.
+	 * If the write failed, return the real error code immediately.
+	 * This prevents it from being overwritten by the short write check below.
 	 */
-
-	remain = arg->size;
-	offset = arg->offset;
-	pg = offset_in_page(offset);
-
-	do {
-		unsigned int len, unwritten;
-		struct page *page;
-		void *data, *vaddr;
-		int err;
-		char __maybe_unused c;
-
-		len = PAGE_SIZE - pg;
-		if (len > remain)
-			len = remain;
-
-		/* Prefault the user page to reduce potential recursion */
-		err = __get_user(c, user_data);
-		if (err)
-			return err;
-
-		err = __get_user(c, user_data + len - 1);
-		if (err)
-			return err;
-
-		err = aops->write_begin(obj->base.filp, mapping, offset, len,
-					&page, &data);
-		if (err < 0)
-			return err;
-
-		vaddr = kmap_atomic(page);
-		unwritten = __copy_from_user_inatomic(vaddr + pg,
-						      user_data,
-						      len);
-		kunmap_atomic(vaddr);
-
-		err = aops->write_end(obj->base.filp, mapping, offset, len,
-				      len - unwritten, page, data);
-		if (err < 0)
-			return err;
-
-		/* We don't handle -EFAULT, leave it to the caller to check */
-		if (unwritten)
-			return -ENODEV;
-
-		remain -= len;
-		user_data += len;
-		offset += len;
-		pg = 0;
-	} while (remain);
+	if (written < 0)
+		return written;
+	/*
+	 * Check for a short write (written bytes != requested size).
+	 * Even if some data was written, return -EIO to indicate that the
+	 * write was not fully completed.
+	 */
+	if (written != size)
+		return -EIO;
 
 	return 0;
 }
@@ -570,6 +523,13 @@ static int __create_shmem(struct drm_i915_private *i915,
 	if (IS_ERR(filp))
 		return PTR_ERR(filp);
 
+	/*
+	 * Prevent -EFBIG by allowing large writes beyond MAX_NON_LFS on shmem
+	 * objects by setting O_LARGEFILE.
+	 */
+	if (force_o_largefile())
+		filp->f_flags |= O_LARGEFILE;
+
 	obj->filp = filp;
 	return 0;
 }
@@ -649,48 +609,31 @@ i915_gem_object_create_shmem(struct drm_i915_private *i915,
 
 /* Allocate a new GEM object and fill it with the supplied data */
 struct drm_i915_gem_object *
-i915_gem_object_create_shmem_from_data(struct drm_i915_private *dev_priv,
+i915_gem_object_create_shmem_from_data(struct drm_i915_private *i915,
 				       const void *data, resource_size_t size)
 {
 	struct drm_i915_gem_object *obj;
 	struct file *file;
-	const struct address_space_operations *aops;
-	resource_size_t offset;
-	int err;
+	loff_t pos = 0;
+	ssize_t err;
 
-	GEM_WARN_ON(IS_DGFX(dev_priv));
-	obj = i915_gem_object_create_shmem(dev_priv, round_up(size, PAGE_SIZE));
+	GEM_WARN_ON(IS_DGFX(i915));
+	obj = i915_gem_object_create_shmem(i915, round_up(size, PAGE_SIZE));
 	if (IS_ERR(obj))
 		return obj;
 
 	GEM_BUG_ON(obj->write_domain != I915_GEM_DOMAIN_CPU);
 
 	file = obj->base.filp;
-	aops = file->f_mapping->a_ops;
-	offset = 0;
-	do {
-		unsigned int len = min_t(typeof(size), size, PAGE_SIZE);
-		struct page *page;
-		void *pgdata, *vaddr;
-
-		err = aops->write_begin(file, file->f_mapping, offset, len,
-					&page, &pgdata);
-		if (err < 0)
-			goto fail;
-
-		vaddr = kmap(page);
-		memcpy(vaddr, data, len);
-		kunmap(page);
-
-		err = aops->write_end(file, file->f_mapping, offset, len, len,
-				      page, pgdata);
-		if (err < 0)
-			goto fail;
-
-		size -= len;
-		data += len;
-		offset += len;
-	} while (size);
+	err = kernel_write(file, data, size, &pos);
+
+	if (err < 0)
+		goto fail;
+
+	if (err != size) {
+		err = -EIO;
+		goto fail;
+	}
 
 	return obj;