From c34cd7750e2497684d4d3917e14212fc403c7760 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@google.com>
Date: Wed, 19 May 2021 17:03:34 +0200
Subject: [PATCH] Revert "mm: fix struct page layout on 32-bit systems"

This reverts commit cfddf6a685e3bbdba0c9976563810ecb118fa516 as it
breaks the kernel abi at the moment.  It will be restored at a later
point in time.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ic4dd11b89bcfd8ded25e4cb39f16967b22f5fa88
---
 include/linux/mm_types.h |  4 ++--
 include/net/page_pool.h  | 12 +-----------
 net/core/page_pool.c     | 12 +++++-------
 3 files changed, 8 insertions(+), 20 deletions(-)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 50648bc12864..8b13a87c1657 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -98,10 +98,10 @@ struct page {
 		};
 		struct {	/* page_pool used by netstack */
 			/**
-			 * @dma_addr: might require a 64-bit value on
+			 * @dma_addr: might require a 64-bit value even on
 			 * 32-bit architectures.
 			 */
-			unsigned long dma_addr[2];
+			dma_addr_t dma_addr;
 		};
 		struct {	/* slab, slob and slub */
 			union {
diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index b139e7bf45fe..81d7773f96cd 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -191,17 +191,7 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
 
 static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
 {
-	dma_addr_t ret = page->dma_addr[0];
-	if (sizeof(dma_addr_t) > sizeof(unsigned long))
-		ret |= (dma_addr_t)page->dma_addr[1] << 16 << 16;
-	return ret;
-}
-
-static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
-{
-	page->dma_addr[0] = addr;
-	if (sizeof(dma_addr_t) > sizeof(unsigned long))
-		page->dma_addr[1] = upper_32_bits(addr);
+	return page->dma_addr;
 }
 
 static inline bool is_page_pool_compiled_in(void)
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 08fbf4049c10..ef98372facf6 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -172,10 +172,8 @@ static void page_pool_dma_sync_for_device(struct page_pool *pool,
 					  struct page *page,
 					  unsigned int dma_sync_size)
 {
-	dma_addr_t dma_addr = page_pool_get_dma_addr(page);
-
 	dma_sync_size = min(dma_sync_size, pool->p.max_len);
-	dma_sync_single_range_for_device(pool->p.dev, dma_addr,
+	dma_sync_single_range_for_device(pool->p.dev, page->dma_addr,
 					 pool->p.offset, dma_sync_size,
 					 pool->p.dma_dir);
 }
@@ -226,7 +224,7 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
 		put_page(page);
 		return NULL;
 	}
-	page_pool_set_dma_addr(page, dma);
+	page->dma_addr = dma;
 
 	if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
 		page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
@@ -294,13 +292,13 @@ void page_pool_release_page(struct page_pool *pool, struct page *page)
 		 */
 		goto skip_dma_unmap;
 
-	dma = page_pool_get_dma_addr(page);
+	dma = page->dma_addr;
 
-	/* When page is unmapped, it cannot be returned to our pool */
+	/* When page is unmapped, it cannot be returned our pool */
 	dma_unmap_page_attrs(pool->p.dev, dma,
 			     PAGE_SIZE << pool->p.order, pool->p.dma_dir,
 			     DMA_ATTR_SKIP_CPU_SYNC);
-	page_pool_set_dma_addr(page, 0);
+	page->dma_addr = 0;
 skip_dma_unmap:
 	/* This may be the last page returned, releasing the pool, so
 	 * it is not safe to reference pool afterwards.