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 diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
  16 index bf56e17..0c97d51 100644
  17 --- a/arch/x86/Kconfig.debug
  18 +++ b/arch/x86/Kconfig.debug
  19 @@ -7,6 +7,7 @@ source "lib/Kconfig.debug"
  20
  21  config STRICT_DEVMEM
  22         bool "Filter access to /dev/mem"
  23 +       depends on DEVMEM
  24         ---help---
  25           If this option is disabled, you allow userspace (root) access to all
  26           of memory, including kernel and userspace memory. Accidental
  27 diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
  28 index 4364303..a2e462e 100644
  29 --- a/drivers/char/Kconfig
  30 +++ b/drivers/char/Kconfig
  31 @@ -6,6 +6,16 @@ menu "Character devices"
  32
  33  source "drivers/tty/Kconfig"
  34
  35 +config DEVMEM
  36 +       bool "/dev/mem virtual device support"
  37 +       default y
  38 +       help
  39 +         Say Y here if you want to support the /dev/mem device.
  40 +         Some X server drivers access the video hardware using this device.
  41 +         Accessing hardware directly from user space can be useful in some
  42 +         cases, but it is not without risks.
  43 +         When in doubt, say "N".
  44 +
  45  config DEVKMEM
  46         bool "/dev/kmem virtual device support"
  47         default y
  48 diff --git a/drivers/char/mem.c b/drivers/char/mem.c
  49 index 1451790..a6020ca 100644
  50 --- a/drivers/char/mem.c
  51 +++ b/drivers/char/mem.c
  52 @@ -87,6 +87,8 @@ void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr)
  53  {
  54  }
  55
  56 +#ifdef CONFIG_DEVMEM
  57 +
  58  /*
  59   * This funcion reads the *physical* memory. The f_pos points directly to the
  60   * memory location.
  61 @@ -210,6 +212,10 @@ static ssize_t write_mem(struct file *file, const char __user *buf,
  62         return written;
  63  }
  64
  65 +#endif
  66 +
  67 +#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM)
  68 +
  69  int __weak phys_mem_access_prot_allowed(struct file *file,
  70         unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
  71  {
  72 @@ -331,6 +337,8 @@ static int mmap_mem(struct file *file, struct vm_area_struct *vma)
  73         return 0;
  74  }
  75
  76 +#endif
  77 +
  78  #ifdef CONFIG_DEVKMEM
  79  static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
  80  {
  81 @@ -694,6 +702,7 @@ static loff_t null_lseek(struct file *file, loff_t offset, int orig)
  82         return file->f_pos = 0;
  83  }
  84
  85 +#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM) || defined(CONFIG_DEVPORT)
  86  /*
  87   * The memory devices use the full 32/64 bits of the offset, and so we cannot
  88   * check against negative addresses: they are ok. The return value is weird,
  89 @@ -726,11 +735,15 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
  90         mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
  91         return ret;
  92  }
  93 +#endif
  94
  95 +#if defined(CONFIG_DEVMEM) || defined(CONFIG_DEVKMEM) || \
  96 +               defined(CONFIG_DEVPORT) || defined(CONFIG_CRASH_DUMP)
  97  static int open_port(struct inode * inode, struct file * filp)
  98  {
  99         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 100  }
 101 +#endif
 102
 103  #define zero_lseek     null_lseek
 104  #define full_lseek      null_lseek
 105 @@ -740,6 +753,7 @@ static int open_port(struct inode * inode, struct file * filp)
 106  #define open_kmem      open_mem
 107  #define open_oldmem    open_mem
 108
 109 +#ifdef CONFIG_DEVMEM
 110  static const struct file_operations mem_fops = {
 111         .llseek         = memory_lseek,
 112         .read           = read_mem,
 113 @@ -748,6 +762,7 @@ static const struct file_operations mem_fops = {
 114         .open           = open_mem,
 115         .get_unmapped_area = get_unmapped_area_mem,
 116  };
 117 +#endif
 118
 119  #ifdef CONFIG_DEVKMEM
 120  static const struct file_operations kmem_fops = {
 121 @@ -851,7 +866,9 @@ static const struct memdev {
 122         const struct file_operations *fops;
 123         struct backing_dev_info *dev_info;
 124  } devlist[] = {
 125 +#ifdef CONFIG_DEVMEM
 126          [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
 127 +#endif
 128  #ifdef CONFIG_DEVKMEM
 129          [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
 130  #endif
 131 --
 132 1.7.5.4
 133