[PATCHv7 02/14] x86/asm: Fix comment in return_from_SYSCALL_64

[Kirill A. Shutemov]

On x86-64 __VIRTUAL_MASK_SHIFT depends on paging mode now.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
 arch/x86/entry/entry_64.S | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 4a4c0834f965..a9a8027a6c0e 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -265,7 +265,8 @@ return_from_SYSCALL_64:
 	 * If width of "canonical tail" ever becomes variable, this will need
 	 * to be updated to remain correct on both old and new CPUs.
 	 *
-	 * Change top 16 bits to be the sign-extension of 47th bit
+	 * Change top bits to match most significant bit (47th or 56th bit
+	 * depending on paging mode) in the address.
 	 */
 	shl	$(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
 	sar	$(64 - (__VIRTUAL_MASK_SHIFT+1)), %rcx
-- 
2.11.0