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Message-ID: <alpine.DEB.2.10.1412030818030.7838@rob-thinkpad>
Date: Wed, 3 Dec 2014 08:21:04 +0000 (GMT)
From: Rob Ward <robert.ward114@...glemail.com>
To: arnd@...db.de, gregkh@...uxfoundation.org
cc: linux-kernel@...r.kernel.org
Subject: [PATCH] drivers: char: mem: Make /dev/mem an optional device
>From ecd3ac31f6be2372d2beac0cc4831e74aeae75d2 Mon Sep 17 00:00:00 2001
From: Rob Ward <robert.ward114@...glemail.com>
Date: Wed, 5 Nov 2014 19:13:53 +0000
Subject: [PATCH] drivers: char: mem: Make /dev/mem an optional device
Adds Kconfig option CONFIG_DEVMEM that allows the
/dev/mem device to be disabled.
Option defaults to /dev/mem enabled.
Signed-off-by: Rob Ward <robert.ward114@...glemail.com>
---
drivers/char/Kconfig | 9 +++++++++
drivers/char/mem.c | 19 ++++++++++++++++++-
2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index efefd12..a4af822 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -6,6 +6,15 @@ menu "Character devices"
source "drivers/tty/Kconfig"
+config DEVMEM
+ bool "/dev/mem virtual device support"
+ default y
+ help
+ Say Y here if you want to support the /dev/mem device.
+ The /dev/mem device is used to access areas of physical
+ memory.
+ When in doubt, say "Y".
+
config DEVKMEM
bool "/dev/kmem virtual device support"
default y
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 524b707..feadc87 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -92,6 +92,7 @@ void __weak unxlate_dev_mem_ptr(unsigned long phys, void *addr)
* This funcion reads the *physical* memory. The f_pos points directly to the
* memory location.
*/
+#ifdef CONFIG_DEVMEM
static ssize_t read_mem(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
@@ -216,6 +217,7 @@ static ssize_t write_mem(struct file *file, const char __user *buf,
*ppos += written;
return written;
}
+#endif
int __weak phys_mem_access_prot_allowed(struct file *file,
unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
@@ -273,6 +275,7 @@ static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
#endif
#ifndef CONFIG_MMU
+#if defined CONFIG_DEVMEM || defined CONFIG_DEVKMEM
static unsigned long get_unmapped_area_mem(struct file *file,
unsigned long addr,
unsigned long len,
@@ -283,14 +286,16 @@ static unsigned long get_unmapped_area_mem(struct file *file,
return (unsigned long) -EINVAL;
return pgoff << PAGE_SHIFT;
}
-
+#endif
/* can't do an in-place private mapping if there's no MMU */
static inline int private_mapping_ok(struct vm_area_struct *vma)
{
return vma->vm_flags & VM_MAYSHARE;
}
#else
+#if defined CONFIG_DEVMEM || defined CONFIG_DEVKMEM
#define get_unmapped_area_mem NULL
+#endif
static inline int private_mapping_ok(struct vm_area_struct *vma)
{
@@ -298,6 +303,7 @@ static inline int private_mapping_ok(struct vm_area_struct *vma)
}
#endif
+#if defined CONFIG_DEVMEM || defined CONFIG_DEVKMEM
static const struct vm_operations_struct mmap_mem_ops = {
#ifdef CONFIG_HAVE_IOREMAP_PROT
.access = generic_access_phys
@@ -337,6 +343,7 @@ static int mmap_mem(struct file *file, struct vm_area_struct *vma)
}
return 0;
}
+#endif
#ifdef CONFIG_DEVKMEM
static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
@@ -675,6 +682,7 @@ static loff_t null_lseek(struct file *file, loff_t offset, int orig)
* also note that seeking relative to the "end of file" isn't supported:
* it has no meaning, so it returns -EINVAL.
*/
+#if defined CONFIG_DEVMEM || defined CONFIG_DEVKMEM || defined CONFIG_DEVPORT
static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
{
loff_t ret;
@@ -704,14 +712,20 @@ static int open_port(struct inode *inode, struct file *filp)
{
return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}
+#endif
#define zero_lseek null_lseek
#define full_lseek null_lseek
#define write_zero write_null
#define aio_write_zero aio_write_null
+#if defined CONFIG_DEVMEM || defined CONFIG_DEVKMEM
#define open_mem open_port
+#endif
+#ifdef CONFIG_DEVKMEM
#define open_kmem open_mem
+#endif
+#ifdef CONFIG_DEVMEM
static const struct file_operations mem_fops = {
.llseek = memory_lseek,
.read = read_mem,
@@ -720,6 +734,7 @@ static const struct file_operations mem_fops = {
.open = open_mem,
.get_unmapped_area = get_unmapped_area_mem,
};
+#endif
#ifdef CONFIG_DEVKMEM
static const struct file_operations kmem_fops = {
@@ -782,7 +797,9 @@ static const struct memdev {
const struct file_operations *fops;
struct backing_dev_info *dev_info;
} devlist[] = {
+#ifdef CONFIG_DEVMEM
[1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
+#endif
#ifdef CONFIG_DEVKMEM
[2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
#endif
--
2.0.2
--
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