From: Mikulas Patocka <mpatocka@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 0aed55af88345b ("x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations") Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> Reviewed-by: Dan Williams <dan.j.wiilliams@xxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Cc: Jeff Moyer <jmoyer@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Toshi Kani <toshi.kani@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- 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); _
