patches/kernel/0177-x86-mm-Remove-superfluous-barriers.patch

   1 From bf670c55337b76ab2449abe15d3fd3c11b14c013 Mon Sep 17 00:00:00 2001
   2 From: Peter Zijlstra <peterz@infradead.org>
   3 Date: Tue, 5 Dec 2017 13:34:46 +0100
   4 Subject: [PATCH 177/241] x86/mm: Remove superfluous barriers
   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 atomic64_inc_return() already implies smp_mb() before and after.
  12
  13 Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
  14 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  15 Cc: Andy Lutomirski <luto@kernel.org>
  16 Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
  17 Cc: Borislav Petkov <bp@alien8.de>
  18 Cc: Brian Gerst <brgerst@gmail.com>
  19 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  20 Cc: David Laight <David.Laight@aculab.com>
  21 Cc: Denys Vlasenko <dvlasenk@redhat.com>
  22 Cc: Eduardo Valentin <eduval@amazon.com>
  23 Cc: Greg KH <gregkh@linuxfoundation.org>
  24 Cc: H. Peter Anvin <hpa@zytor.com>
  25 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  26 Cc: Juergen Gross <jgross@suse.com>
  27 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  28 Cc: Peter Zijlstra <peterz@infradead.org>
  29 Cc: Will Deacon <will.deacon@arm.com>
  30 Cc: aliguori@amazon.com
  31 Cc: daniel.gruss@iaik.tugraz.at
  32 Cc: hughd@google.com
  33 Cc: keescook@google.com
  34 Cc: linux-mm@kvack.org
  35 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  36 (cherry picked from commit b5fc6d943808b570bdfbec80f40c6b3855f1c48b)
  37 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  38 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  39 (cherry picked from commit 31a37930df33315a7006b46706f6babdb57db1f4)
  40 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  41 ---
  42  arch/x86/include/asm/tlbflush.h | 8 +-------
  43  1 file changed, 1 insertion(+), 7 deletions(-)
  44
  45 diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
  46 index 6d2688a6fda0..bc1460b4737b 100644
  47 --- a/arch/x86/include/asm/tlbflush.h
  48 +++ b/arch/x86/include/asm/tlbflush.h
  49 @@ -59,19 +59,13 @@ static inline void invpcid_flush_all_nonglobals(void)
  50
  51  static inline u64 inc_mm_tlb_gen(struct mm_struct *mm)
  52  {
  53 -       u64 new_tlb_gen;
  54 -
  55         /*
  56          * Bump the generation count.  This also serves as a full barrier
  57          * that synchronizes with switch_mm(): callers are required to order
  58          * their read of mm_cpumask after their writes to the paging
  59          * structures.
  60          */
  61 -       smp_mb__before_atomic();
  62 -       new_tlb_gen = atomic64_inc_return(&mm->context.tlb_gen);
  63 -       smp_mb__after_atomic();
  64 -
  65 -       return new_tlb_gen;
  66 +       return atomic64_inc_return(&mm->context.tlb_gen);
  67  }
  68
  69  #ifdef CONFIG_PARAVIRT
  70 --
  71 2.14.2
  72