patches/kernel/0146-x86-entry-gdt-Put-per-CPU-GDT-remaps-in-ascending-or.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Andy Lutomirski <luto@kernel.org>
   3 Date: Mon, 4 Dec 2017 15:07:14 +0100
   4 Subject: [PATCH] x86/entry/gdt: Put per-CPU GDT remaps in ascending order
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 CVE-2017-5754
  10
  11 We currently have CPU 0's GDT at the top of the GDT range and
  12 higher-numbered CPUs at lower addresses.  This happens because the
  13 fixmap is upside down (index 0 is the top of the fixmap).
  14
  15 Flip it so that GDTs are in ascending order by virtual address.
  16 This will simplify a future patch that will generalize the GDT
  17 remap to contain multiple pages.
  18
  19 Signed-off-by: Andy Lutomirski <luto@kernel.org>
  20 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  21 Reviewed-by: Borislav Petkov <bp@suse.de>
  22 Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
  23 Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
  24 Cc: Borislav Petkov <bp@alien8.de>
  25 Cc: Borislav Petkov <bpetkov@suse.de>
  26 Cc: Brian Gerst <brgerst@gmail.com>
  27 Cc: Dave Hansen <dave.hansen@intel.com>
  28 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  29 Cc: David Laight <David.Laight@aculab.com>
  30 Cc: Denys Vlasenko <dvlasenk@redhat.com>
  31 Cc: Eduardo Valentin <eduval@amazon.com>
  32 Cc: Greg KH <gregkh@linuxfoundation.org>
  33 Cc: H. Peter Anvin <hpa@zytor.com>
  34 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  35 Cc: Juergen Gross <jgross@suse.com>
  36 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  37 Cc: Peter Zijlstra <peterz@infradead.org>
  38 Cc: Rik van Riel <riel@redhat.com>
  39 Cc: Will Deacon <will.deacon@arm.com>
  40 Cc: aliguori@amazon.com
  41 Cc: daniel.gruss@iaik.tugraz.at
  42 Cc: hughd@google.com
  43 Cc: keescook@google.com
  44 Link: https://lkml.kernel.org/r/20171204150605.471561421@linutronix.de
  45 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  46 (cherry picked from commit aaeed3aeb39c1ba69f0a49baec8cb728121d0a91)
  47 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  48 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  49 (cherry picked from commit 9c37967fad2d6a525df53e0a40edcd652e5abaae)
  50 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  51 ---
  52  arch/x86/include/asm/desc.h | 2 +-
  53  1 file changed, 1 insertion(+), 1 deletion(-)
  54
  55 diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
  56 index f995e5a09136..22ee0a93b4f7 100644
  57 --- a/arch/x86/include/asm/desc.h
  58 +++ b/arch/x86/include/asm/desc.h
  59 @@ -61,7 +61,7 @@ static inline struct desc_struct *get_current_gdt_rw(void)
  60  /* Get the fixmap index for a specific processor */
  61  static inline unsigned int get_cpu_gdt_ro_index(int cpu)
  62  {
  63 -       return FIX_GDT_REMAP_BEGIN + cpu;
  64 +       return FIX_GDT_REMAP_END - cpu;
  65  }
  66
  67  /* Provide the fixmap address of the remapped GDT */
  68 --
  69 2.14.2
  70