[PATCH] dmaengine: async_xor, fix zero address issue when xor highmem page

[<b29237@freescale.com>]

From: Forrest shi <b29237@freescale.com>

	we may do_sync_xor high mem pages, in this case, page_address will
        return zero address which cause a failure.

	this patch uses kmap_atomic before xor the pages and kunmap_atomic
        after it.

	Signed-off-by: b29237@freescale.com <xuelin.shi@freescale.com>
---
 crypto/async_tx/async_xor.c |   16 ++++++++++++----
 1 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/crypto/async_tx/async_xor.c b/crypto/async_tx/async_xor.c
index bc28337..5b416d1 100644
--- a/crypto/async_tx/async_xor.c
+++ b/crypto/async_tx/async_xor.c
@@ -26,6 +26,7 @@
 #include <linux/kernel.h>
 #include <linux/interrupt.h>
 #include <linux/mm.h>
+#include <linux/highmem.h>
 #include <linux/dma-mapping.h>
 #include <linux/raid/xor.h>
 #include <linux/async_tx.h>
@@ -126,7 +127,7 @@ do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 	    int src_cnt, size_t len, struct async_submit_ctl *submit)
 {
 	int i;
-	int xor_src_cnt = 0;
+	int xor_src_cnt = 0, kmap_cnt=0;
 	int src_off = 0;
 	void *dest_buf;
 	void **srcs;
@@ -138,11 +139,13 @@ do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 
 	/* convert to buffer pointers */
 	for (i = 0; i < src_cnt; i++)
-		if (src_list[i])
-			srcs[xor_src_cnt++] = page_address(src_list[i]) + offset;
+		if (src_list[i]) {
+			srcs[xor_src_cnt++] = kmap_atomic(src_list[i], KM_USER1) + offset;
+		}
+	kmap_cnt = xor_src_cnt;
 	src_cnt = xor_src_cnt;
 	/* set destination address */
-	dest_buf = page_address(dest) + offset;
+	dest_buf = kmap_atomic(dest, KM_USER0) + offset;
 
 	if (submit->flags & ASYNC_TX_XOR_ZERO_DST)
 		memset(dest_buf, 0, len);
@@ -157,6 +160,11 @@ do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset,
 		src_off += xor_src_cnt;
 	}
 
+	kunmap_atomic(dest_buf, KM_USER0);
+	for (i = 0; i < kmap_cnt; i++) 
+		if (src_list[i])
+			kunmap_atomic(srcs[i], KM_USER1);
+
 	async_tx_sync_epilog(submit);
 }
 
-- 
1.7.0.4