From 48085c7ec07d24f322fbf56dfda77264b31e53b2 Mon Sep 17 00:00:00 2001 From: Alexander Kuleshov <kuleshovmail@gmail.com> Date: Thu, 14 Jun 2018 14:56:07 -0700 Subject: [PATCH 015/103] x86/boot: Simplify kernel load address alignment check commit a4733143085d6c782ac1e6c85778655b6bac1d4e upstream 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 <brgerst@gmail.com> Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Alexander Popov <alpopov@ptsecurity.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> 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 <mingo@kernel.org> Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu> --- arch/x86/kernel/head_64.S | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 4034e90..734ba1d 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 /* -- 2.7.4