target/linux/xburst/patches-3.2/0009-dev-mem-Add-kernel-config-option-to-omit-this-device.patch

   1 From 4003b9a2c05f4d0d37535c3dffbf4a7b47d5c36c Mon Sep 17 00:00:00 2001
   2 From: Maarten ter Huurne <maarten@treewalker.org>
   3 Date: Wed, 8 Sep 2010 02:31:19 +0200
   4 Subject: [PATCH 09/21] /dev/mem: Add kernel config option to omit this
   5  device.
   6
   7 Omitting this device prevents software from accessing the hardware directly, which can cause trouble if the kernel accesses the same hardware.
   8 It also saves some space on embedded systems.
   9 ---
  10  arch/x86/Kconfig.debug |    1 +
  11  drivers/char/Kconfig   |   10 ++++++++++
  12  drivers/char/mem.c     |   17 +++++++++++++++++
  13  3 files changed, 28 insertions(+), 0 deletions(-)
  14
  15 --- a/arch/x86/Kconfig.debug
  16 +++ b/arch/x86/Kconfig.debug
  17 @@ -7,6 +7,7 @@ source "lib/Kconfig.debug"
  18
  19  config STRICT_DEVMEM
  20         bool "Filter access to /dev/mem"
  21 +       depends on DEVMEM
  22         ---help---
  23           If this option is disabled, you allow userspace (root) access to all
  24           of memory, including kernel and userspace memory. Accidental
  25 --- a/drivers/char/Kconfig
  26 +++ b/drivers/char/Kconfig
  27 @@ -6,6 +6,16 @@ menu "Character devices"
  28
  29  source "drivers/tty/Kconfig"
  30
  31 +config DEVMEM
  32 +       bool "/dev/mem virtual device support"
  33 +       default y
  34 +       help
  35 +         Say Y here if you want to support the /dev/mem device.
  36 +         Some X server drivers access the video hardware using this device.
  37 +         Accessing hardware directly from user space can be useful in some
  38 +         cases, but it is not without risks.
  39 +         When in doubt, say "N".
  40 +
  41  config DEVKMEM
  42         bool "/dev/kmem virtual device support"
  43         default y
  44 --- a/drivers/char/mem.c
  45 +++ b/drivers/char/mem.c
  46 @@ -87,6 +87,8 @@ void __weak unxlate_dev_mem_ptr(unsigned
  47  {
  48  }
  49
  50 +#ifdef CONFIG_DEVMEM
  51 +
  52  /*
  53   * This funcion reads the *physical* memory. The f_pos points directly to the
  54   * memory location.
  55 @@ -210,6 +212,10 @@ static ssize_t write_mem(struct file *fi
  56         return written;
  57  }
  58
  59 +#endif
  60 +
  61 +#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM)
  62 +
  63  int __weak phys_mem_access_prot_allowed(struct file *file,
  64         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
  65  {
  66 @@ -331,6 +337,8 @@ static int mmap_mem(struct file *file, s
  67         return 0;
  68  }
  69
  70 +#endif
  71 +
  72  #ifdef CONFIG_DEVKMEM
  73  static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
  74  {
  75 @@ -694,6 +702,7 @@ static loff_t null_lseek(struct file *fi
  76         return file->f_pos = 0;
  77  }
  78
  79 +#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM) || defined(CONFIG_DEVPORT)
  80  /*
  81   * The memory devices use the full 32/64 bits of the offset, and so we cannot
  82   * check against negative addresses: they are ok. The return value is weird,
  83 @@ -726,11 +735,15 @@ static loff_t memory_lseek(struct file *
  84         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
  85         return ret;
  86  }
  87 +#endif
  88
  89 +#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM) || \
  90 +               defined(CONFIG_DEVPORT) || defined(CONFIG_CRASH_DUMP)
  91  static int open_port(struct inode * inode, struct file * filp)
  92  {
  93         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
  94  }
  95 +#endif
  96
  97  #define zero_lseek     null_lseek
  98  #define full_lseek      null_lseek
  99 @@ -740,6 +753,7 @@ static int open_port(struct inode * inod
 100  #define open_kmem      open_mem
 101  #define open_oldmem    open_mem
 102
 103 +#ifdef CONFIG_DEVMEM
 104  static const struct file_operations mem_fops = {
 105         .llseek         = memory_lseek,
 106         .read           = read_mem,
 107 @@ -748,6 +762,7 @@ static const struct file_operations mem_
 108         .open           = open_mem,
 109         .get_unmapped_area = get_unmapped_area_mem,
 110  };
 111 +#endif
 112
 113  #ifdef CONFIG_DEVKMEM
 114  static const struct file_operations kmem_fops = {
 115 @@ -851,7 +866,9 @@ static const struct memdev {
 116         const struct file_operations *fops;
 117         struct backing_dev_info *dev_info;
 118  } devlist[] = {
 119 +#ifdef CONFIG_DEVMEM
 120          [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
 121 +#endif
 122  #ifdef CONFIG_DEVKMEM
 123          [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
 124  #endif