Curiously, the Crypto API scatterwalk incremented pages by hand
rather than using nth_page. Possibly because scatterwalk predates
nth_page (the following commit is from the history tree):
commit 3957f2b34960d85b63e814262a8be7d5ad91444d
Author: James Morris <jmorris@xxxxxxxxxxxxxxxx>
Date: Sun Feb 2 07:35:32 2003 -0800
[CRYPTO]: in/out scatterlist support for ciphers.
Fix this by using nth_page.
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
---
include/crypto/scatterwalk.h | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h
index b7e617ae4442..4fc70b8422c5 100644
--- a/include/crypto/scatterwalk.h
+++ b/include/crypto/scatterwalk.h
@@ -99,26 +99,27 @@ static inline void scatterwalk_get_sglist(struct scatter_walk *walk,
static inline void scatterwalk_map(struct scatter_walk *walk)
{
- struct page *base_page = sg_page(walk->sg);
+ struct page *page = sg_page(walk->sg);
+ unsigned int offset = walk->offset;
+ void *addr;
+
+ page = nth_page(page, offset >> PAGE_SHIFT);
+ offset = offset_in_page(offset);
if (IS_ENABLED(CONFIG_HIGHMEM)) {
- walk->__addr = kmap_local_page(base_page +
- (walk->offset >> PAGE_SHIFT)) +
- offset_in_page(walk->offset);
+ addr = kmap_local_page(page) + offset;
} else {
/*
* When !HIGHMEM we allow the walker to return segments that
* span a page boundary; see scatterwalk_clamp(). To make it
* clear that in this case we're working in the linear buffer of
* the whole sg entry in the kernel's direct map rather than
- * within the mapped buffer of a single page, compute the
- * address as an offset from the page_address() of the first
- * page of the sg entry. Either way the result is the address
- * in the direct map, but this makes it clearer what is really
- * going on.
+ * within the mapped buffer of a single page, use
+ * page_address() instead of going through kmap.
*/
- walk->__addr = page_address(base_page) + walk->offset;
+ addr = page_address(page) + offset;
}
+ walk->__addr = addr;
}
/**
--
2.39.5
