releases/4.4.181/hwmon-f71805f-use-request_muxed_region-for-super-io-.patch

   1 From 8c20e729f900e90d3b7bfbbb6d585e6e792a11b5 Mon Sep 17 00:00:00 2001
   2 From: Guenter Roeck <linux@roeck-us.net>
   3 Date: Thu, 4 Apr 2019 10:52:43 -0700
   4 Subject: hwmon: (f71805f) Use request_muxed_region for Super-IO accesses
   5
   6 [ Upstream commit 73e6ff71a7ea924fb7121d576a2d41e3be3fc6b5 ]
   7
   8 Super-IO accesses may fail on a system with no or unmapped LPC bus.
   9
  10 Unable to handle kernel paging request at virtual address ffffffbffee0002e
  11 pgd = ffffffc1d68d4000
  12 [ffffffbffee0002e] *pgd=0000000000000000, *pud=0000000000000000
  13 Internal error: Oops: 94000046 [#1] PREEMPT SMP
  14 Modules linked in: f71805f(+) hwmon
  15 CPU: 3 PID: 1659 Comm: insmod Not tainted 4.5.0+ #88
  16 Hardware name: linux,dummy-virt (DT)
  17 task: ffffffc1f6665400 ti: ffffffc1d6418000 task.ti: ffffffc1d6418000
  18 PC is at f71805f_find+0x6c/0x358 [f71805f]
  19
  20 Also, other drivers may attempt to access the LPC bus at the same time,
  21 resulting in undefined behavior.
  22
  23 Use request_muxed_region() to ensure that IO access on the requested
  24 address space is supported, and to ensure that access by multiple
  25 drivers is synchronized.
  26
  27 Fixes: e53004e20a58e ("hwmon: New f71805f driver")
  28 Reported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
  29 Reported-by: John Garry <john.garry@huawei.com>
  30 Cc: John Garry <john.garry@huawei.com>
  31 Acked-by: John Garry <john.garry@huawei.com>
  32 Signed-off-by: Guenter Roeck <linux@roeck-us.net>
  33 Signed-off-by: Sasha Levin <sashal@kernel.org>
  34 ---
  35  drivers/hwmon/f71805f.c | 15 ++++++++++++---
  36  1 file changed, 12 insertions(+), 3 deletions(-)
  37
  38 diff --git a/drivers/hwmon/f71805f.c b/drivers/hwmon/f71805f.c
  39 index facd05cda26da..e8c0898864277 100644
  40 --- a/drivers/hwmon/f71805f.c
  41 +++ b/drivers/hwmon/f71805f.c
  42 @@ -96,17 +96,23 @@ superio_select(int base, int ld)
  43         outb(ld, base + 1);
  44  }
  45
  46 -static inline void
  47 +static inline int
  48  superio_enter(int base)
  49  {
  50 +       if (!request_muxed_region(base, 2, DRVNAME))
  51 +               return -EBUSY;
  52 +
  53         outb(0x87, base);
  54         outb(0x87, base);
  55 +
  56 +       return 0;
  57  }
  58
  59  static inline void
  60  superio_exit(int base)
  61  {
  62         outb(0xaa, base);
  63 +       release_region(base, 2);
  64  }
  65
  66  /*
  67 @@ -1561,7 +1567,7 @@ static int __init f71805f_device_add(unsigned short address,
  68  static int __init f71805f_find(int sioaddr, unsigned short *address,
  69                                struct f71805f_sio_data *sio_data)
  70  {
  71 -       int err = -ENODEV;
  72 +       int err;
  73         u16 devid;
  74
  75         static const char * const names[] = {
  76 @@ -1569,8 +1575,11 @@ static int __init f71805f_find(int sioaddr, unsigned short *address,
  77                 "F71872F/FG or F71806F/FG",
  78         };
  79
  80 -       superio_enter(sioaddr);
  81 +       err = superio_enter(sioaddr);
  82 +       if (err)
  83 +               return err;
  84
  85 +       err = -ENODEV;
  86         devid = superio_inw(sioaddr, SIO_REG_MANID);
  87         if (devid != SIO_FINTEK_ID)
  88                 goto exit;
  89 --
  90 2.20.1
  91