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-rw-r--r--kernel/crypto/scatterwalk.c45
1 files changed, 34 insertions, 11 deletions
diff --git a/kernel/crypto/scatterwalk.c b/kernel/crypto/scatterwalk.c
index 3bd749c7b..ea5815c5e 100644
--- a/kernel/crypto/scatterwalk.c
+++ b/kernel/crypto/scatterwalk.c
@@ -54,7 +54,11 @@ static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
struct page *page;
page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
- if (!PageSlab(page))
+ /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
+ * PageSlab cannot be optimised away per se due to
+ * use of volatile pointer.
+ */
+ if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
flush_dcache_page(page);
}
@@ -104,22 +108,18 @@ void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
unsigned int start, unsigned int nbytes, int out)
{
struct scatter_walk walk;
- unsigned int offset = 0;
+ struct scatterlist tmp[2];
if (!nbytes)
return;
- for (;;) {
- scatterwalk_start(&walk, sg);
-
- if (start < offset + sg->length)
- break;
+ sg = scatterwalk_ffwd(tmp, sg, start);
- offset += sg->length;
- sg = sg_next(sg);
- }
+ if (sg_page(sg) == virt_to_page(buf) &&
+ sg->offset == offset_in_page(buf))
+ return;
- scatterwalk_advance(&walk, start - offset);
+ scatterwalk_start(&walk, sg);
scatterwalk_copychunks(buf, &walk, nbytes, out);
scatterwalk_done(&walk, out, 0);
}
@@ -146,3 +146,26 @@ int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes)
return n;
}
EXPORT_SYMBOL_GPL(scatterwalk_bytes_sglen);
+
+struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
+ struct scatterlist *src,
+ unsigned int len)
+{
+ for (;;) {
+ if (!len)
+ return src;
+
+ if (src->length > len)
+ break;
+
+ len -= src->length;
+ src = sg_next(src);
+ }
+
+ sg_init_table(dst, 2);
+ sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);
+ scatterwalk_crypto_chain(dst, sg_next(src), 0, 2);
+
+ return dst;
+}
+EXPORT_SYMBOL_GPL(scatterwalk_ffwd);