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Date: Tue, 26 Jan 2016 22:12:10 +0100 From: Borislav Petkov <bp@...en8.de> To: Ingo Molnar <mingo@...nel.org> Cc: LKML <linux-kernel@...r.kernel.org> Subject: [PATCH 10/10] x86/head_64: Simplify kernel load address alignment check From: Alexander Kuleshov <kuleshovmail@...il.com> 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@...il.com> Signed-off-by: Alexander Kuleshov <kuleshovmail@...il.com> Cc: Alexander Popov <alpopov@...ecurity.com> Cc: Andrey Ryabinin <ryabinin.a.a@...il.com> Cc: Andy Lutomirski <luto@...nel.org> Cc: Denys Vlasenko <dvlasenk@...hat.com> Cc: "H. Peter Anvin" <hpa@...or.com> Cc: Ingo Molnar <mingo@...hat.com> Cc: Thomas Gleixner <tglx@...utronix.de> Link: http://lkml.kernel.org/r/1453531828-19291-1-git-send-email-kuleshovmail@gmail.com Signed-off-by: Borislav Petkov <bp@...e.de> --- 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 ffdc0e860390..7c21029cb733 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 /* -- 2.3.5
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