[7/9] arch/x86/lib/usercopy_64.c: fix __copy_user_flushcache() cache writeback

Commit Message

Andrew Morton Sept. 26, 2020, 4:19 a.m. UTC

From: Mikulas Patocka <[e-mail]>
Subject: arch/x86/lib/usercopy_64.c: fix  __copy_user_flushcache() cache writeback

If we copy less than 8 bytes and if the destination crosses a cache line,
__copy_user_flushcache would invalidate only the first cache line.  This
patch makes it invalidate the second cache line as well.

Link: https://lkml.kernel.org/r/[e-mail]
Fixes: 0aed55af88345b ("x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations")
Signed-off-by: Mikulas Patocka <[e-mail]>
Reviewed-by: Dan Williams <[e-mail]>
Cc: Jan Kara <[e-mail]>
Cc: Jeff Moyer <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Toshi Kani <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Al Viro <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Ross Zwisler <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 arch/x86/lib/usercopy_64.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

--- a/arch/x86/lib/usercopy_64.c~arch-x86-lib-usercopy_64c-fix-__copy_user_flushcache-cache-writeback
+++ a/arch/x86/lib/usercopy_64.c
@@ -120,7 +120,7 @@  long __copy_user_flushcache(void *dst, c
 	 */
 	if (size < 8) {
 		if (!IS_ALIGNED(dest, 4) || size != 4)
-			clean_cache_range(dst, 1);
+			clean_cache_range(dst, size);
 	} else {
 		if (!IS_ALIGNED(dest, 8)) {
 			dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);