4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Alexander Kuleshov <kuleshovm...@gmail.com> 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 <brge...@gmail.com> Signed-off-by: Alexander Kuleshov <kuleshovm...@gmail.com> Signed-off-by: Borislav Petkov <b...@suse.de> Cc: Alexander Popov <alpo...@ptsecurity.com> Cc: Andrey Ryabinin <ryabinin....@gmail.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Andy Lutomirski <l...@kernel.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/1453531828-19291-1-git-send-email-kuleshovm...@gmail.com Link: http://lkml.kernel.org/r/1453842730-28463-11-git-send-email...@alien8.de Signed-off-by: Ingo Molnar <mi...@kernel.org> Signed-off-by: Srivatsa S. Bhat <sriva...@csail.mit.edu> Reviewed-by: Matt Helsley (VMware) <matt.hels...@gmail.com> Reviewed-by: Alexey Makhalov <amakha...@vmware.com> Reviewed-by: Bo Gan <g...@vmware.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- arch/x86/kernel/head_64.S | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- 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 /*
