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

1From 4003b9a2c05f4d0d37535c3dffbf4a7b47d5c36c Mon Sep 17 00:00:00 2001
2From: Maarten ter Huurne <maarten@treewalker.org>
3Date: Wed, 8 Sep 2010 02:31:19 +0200
4Subject: [PATCH 09/28] /dev/mem: Add kernel config option to omit this
5 device.
6
7Omitting this device prevents software from accessing the hardware directly, which can cause trouble if the kernel accesses the same hardware.
8It 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
15diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
16index 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
27diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
28index 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
48diff --git a/drivers/char/mem.c b/drivers/char/mem.c
49index 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--
1321.7.5.4
133
134

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