| From foo@baz Sun Jul 15 12:18:31 CEST 2018 |
| From: "Srivatsa S. Bhat" <srivatsa@csail.mit.edu> |
| Date: Sat, 14 Jul 2018 02:27:46 -0700 |
| Subject: x86/boot: Simplify kernel load address alignment check |
| To: gregkh@linuxfoundation.org, stable@vger.kernel.org |
| Cc: Brian Gerst <brgerst@gmail.com>, Alexander Kuleshov <kuleshovmail@gmail.com>, Borislav Petkov <bp@suse.de>, Alexander Popov <alpopov@ptsecurity.com>, Andrey Ryabinin <ryabinin.a.a@gmail.com>, Andy Lutomirski <luto@amacapital.net>, Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>, Denys Vlasenko <dvlasenk@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, Linus Torvalds <torvalds@linux-foundation.org>, Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>, "Matt Helsley \(VMware\)" <matt.helsley@gmail.com>, Alexey Makhalov <amakhalov@vmware.com>, Bo Gan <ganb@vmware.com>, matt.helsley@gmail.com, rostedt@goodmis.org, amakhalov@vmware.com, ganb@vmware.com, srivatsa@csail.mit.edu, srivatsab@vmware.com |
| Message-ID: <153156046632.10043.12222368761298728509.stgit@srivatsa-ubuntu> |
| |
| From: Alexander Kuleshov <kuleshovmail@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 <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> |
| Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com> |
| Reviewed-by: Alexey Makhalov <amakhalov@vmware.com> |
| Reviewed-by: Bo Gan <ganb@vmware.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@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 |
| |
| /* |
