patches/kernel/0260-locking-barriers-introduce-new-memory-barrier-gmb.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: Elena Reshetova <elena.reshetova@intel.com>
   3 Date: Mon, 4 Sep 2017 13:11:43 +0300
   4 Subject: [PATCH] locking/barriers: introduce new memory barrier gmb()
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 CVE-2017-5753
  10 CVE-2017-5715
  11
  12 In constrast to existing mb() and rmb() barriers,
  13 gmb() barrier is arch-independent and can be used to
  14 implement any type of memory barrier.
  15 In x86 case, it is either lfence or mfence, based on
  16 processor type. ARM and others can define it according
  17 to their needs.
  18
  19 Suggested-by: Arjan van de Ven <arjan@linux.intel.com>
  20 Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
  21 Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
  22 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  23 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  24 (cherry picked from commit 6834bd7e6159da957a6c01deebf16132a694bc23)
  25 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  26 ---
  27  arch/x86/include/asm/barrier.h | 3 +++
  28  include/asm-generic/barrier.h  | 4 ++++
  29  2 files changed, 7 insertions(+)
  30
  31 diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
  32 index bfb28caf97b1..aae78054cae2 100644
  33 --- a/arch/x86/include/asm/barrier.h
  34 +++ b/arch/x86/include/asm/barrier.h
  35 @@ -23,6 +23,9 @@
  36  #define wmb()  asm volatile("sfence" ::: "memory")
  37  #endif
  38
  39 +#define gmb() alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC, \
  40 +                                      "lfence", X86_FEATURE_LFENCE_RDTSC);
  41 +
  42  #ifdef CONFIG_X86_PPRO_FENCE
  43  #define dma_rmb()      rmb()
  44  #else
  45 diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
  46 index fe297b599b0a..0ee1345c9222 100644
  47 --- a/include/asm-generic/barrier.h
  48 +++ b/include/asm-generic/barrier.h
  49 @@ -42,6 +42,10 @@
  50  #define wmb()  mb()
  51  #endif
  52
  53 +#ifndef gmb
  54 +#define gmb()  do { } while (0)
  55 +#endif
  56 +
  57  #ifndef dma_rmb
  58  #define dma_rmb()      rmb()
  59  #endif
  60 --
  61 2.14.2
  62