From: Mikulas Patocka mpatocka@redhat.com 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/alpine.LRH.2.02.2009161451140.21915@file01.intrane... Fixes: 0aed55af88345b ("x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations") Signed-off-by: Mikulas Patocka mpatocka@redhat.com Reviewed-by: Dan Williams dan.j.wiilliams@intel.com Cc: Jan Kara jack@suse.cz Cc: Jeff Moyer jmoyer@redhat.com Cc: Ingo Molnar mingo@redhat.com Cc: Christoph Hellwig hch@lst.de Cc: Toshi Kani toshi.kani@hpe.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Al Viro viro@zeniv.linux.org.uk Cc: Thomas Gleixner tglx@linutronix.de Cc: Matthew Wilcox mawilcox@microsoft.com Cc: Ross Zwisler ross.zwisler@linux.intel.com Cc: Ingo Molnar mingo@elte.hu Cc: "H. Peter Anvin" hpa@zytor.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

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

--- 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); _