target/linux/brcm2708/patches-4.4/0215-copy_from_user-CPU_SW_DOMAIN_PAN-compatibility.patch

   1 From cfe94ad9e10d75790f783296006c60fb89beb321 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Tue, 29 Mar 2016 15:32:30 +0100
   4 Subject: [PATCH] copy_from_user: CPU_SW_DOMAIN_PAN compatibility
   5
   6 The downstream copy_from_user acceleration must also play nice with
   7 CONFIG_CPU_SW_DOMAIN_PAN.
   8
   9 See: https://github.com/raspberrypi/linux/issues/1381
  10
  11 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  12 ---
  13  arch/arm/lib/uaccess_with_memcpy.c | 14 +++++++++++---
  14  1 file changed, 11 insertions(+), 3 deletions(-)
  15
  16 --- a/arch/arm/lib/uaccess_with_memcpy.c
  17 +++ b/arch/arm/lib/uaccess_with_memcpy.c
  18 @@ -186,6 +186,7 @@ out:
  19  unsigned long noinline
  20  __copy_from_user_memcpy(void *to, const void __user *from, unsigned long n)
  21  {
  22 +       unsigned long ua_flags;
  23         int atomic;
  24
  25         if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
  26 @@ -217,7 +218,9 @@ __copy_from_user_memcpy(void *to, const
  27                 if (tocopy > n)
  28                         tocopy = n;
  29
  30 +               ua_flags = uaccess_save_and_enable();
  31                 memcpy(to, (const void *)from, tocopy);
  32 +               uaccess_restore(ua_flags);
  33                 to += tocopy;
  34                 from += tocopy;
  35                 n -= tocopy;
  36 @@ -261,9 +264,14 @@ arm_copy_from_user(void *to, const void
  37          * With frame pointer disabled, tail call optimization kicks in
  38          * as well making this test almost invisible.
  39          */
  40 -       if (n < COPY_FROM_USER_THRESHOLD)
  41 -               return __copy_from_user_std(to, from, n);
  42 -       return __copy_from_user_memcpy(to, from, n);
  43 +       if (n < COPY_TO_USER_THRESHOLD) {
  44 +               unsigned long ua_flags = uaccess_save_and_enable();
  45 +               n = __copy_from_user_std(to, from, n);
  46 +               uaccess_restore(ua_flags);
  47 +       } else {
  48 +               n = __copy_from_user_memcpy(to, from, n);
  49 +       }
  50 +       return n;
  51  }
  52
  53  static unsigned long noinline