From a4733143085d6c782ac1e6c85778655b6bac1d4e Mon Sep 17 00:00:00 2001 From: Alexander Kuleshov Date: Tue, 26 Jan 2016 22:12:10 +0100 Subject: x86/boot: Simplify kernel load address alignment check We are using %rax as temporary register to check the kernel address alignment. We don't really have to since the TEST instruction does not clobber the destination operand. Suggested-by: Brian Gerst Signed-off-by: Alexander Kuleshov Signed-off-by: Borislav Petkov Cc: Alexander Popov Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1453531828-19291-1-git-send-email-kuleshovmail@gmail.com Link: http://lkml.kernel.org/r/1453842730-28463-11-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/head_64.S | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'arch/x86/kernel/head_64.S') diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index ffdc0e8..7c21029 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -76,9 +76,7 @@ startup_64: subq $_text - __START_KERNEL_map, %rbp /* Is the address not 2M aligned? */ - movq %rbp, %rax - andl $~PMD_PAGE_MASK, %eax - testl %eax, %eax + testl $~PMD_PAGE_MASK, %ebp jnz bad_address /* -- cgit v1.1