/*
* linux/drivers/char/mem.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* Added devfs support.
* Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
* Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
*/
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/raw.h>
#include <linux/tty.h>
#include <linux/capability.h>
#include <linux/ptrace.h>
#include <linux/device.h>
#include <linux/highmem.h>
#include <linux/crash_dump.h>
#include <linux/backing-dev.h>
#include <linux/bootmem.h>
#include <linux/splice.h>
#include <linux/pfn.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#ifdef CONFIG_IA64
# include <linux/efi.h>
#endif
/*
* Architectures vary in how they handle caching for addresses
* outside of main memory.
*
*/
static inline int uncached_access(struct file *file, unsigned long addr)
{
#if defined(CONFIG_IA64)
/*
* On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
*/
return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
#elif defined(CONFIG_MIPS)
{
extern int __uncached_access(struct file *file,
unsigned long addr);
return __uncached_access(file, addr);
}
#else
/*
* Accessing memory above the top the kernel knows about or through a file pointer
* that was marked O_SYNC will be done non-cached.
*/
if (file->f_flags & O_SYNC)
return 1;
return addr >= __pa(high_memory);
#endif
}
#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
static inline int valid_phys_addr_range(unsigned long addr, size_t count)
{
if (addr + count > __pa(high_memory))
return 0;
return 1;
}
static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
{
return 1;
}
#endif
#ifdef CONFIG_STRICT_DEVMEM
static inline int range_is_allowed(unsigned long pfn, unsigned long size)
{
u64 from = ((u64)pfn) << PAGE_SHIFT;
u64 to = from + size;
u64 cursor = from;
while (cursor < to) {
if (!devmem_is_allowed(pfn)) {
printk(KERN_INFO
"Program %s tried to access /dev/mem between %Lx->%Lx.\n",
current->comm, from, to);
return 0;
}
cursor += PAGE_SIZE;
pfn++;
}
return 1;
}
#else
static inline int range_is_allowed(unsigned long pfn, unsigned long size)
{
return 1;
}
#endif
void __attribute__((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.
*/
static ssize_t read_mem(struct file * file, char __user * buf,
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
ssize_t read, sz;
char *ptr;
if (!valid_phys_addr_range(p, count))
return -EFAULT;
read = 0;
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
/* we don't have page 0 mapped on sparc and m68k.. */
if (p < PAGE_SIZE) {
sz = PAGE_SIZE - p;
if (sz > count)
sz = count;
if (sz > 0) {
if (clear_user(buf, sz))
return -EFAULT;
buf += sz;
p += sz;
count -= sz;
read += sz;
}
}
#endif
while (count > 0) {
/*
* Handle first page in case it's not aligned
*/
if (-p & (PAGE_SIZE - 1))
sz = -p & (PAGE_SIZE - 1);
else
sz = PAGE_SIZE;
sz = min_t(unsigned long, sz, count);
if (!range_is_allowed(p >> PAGE_SHIFT, count))
return -EPERM;
/*
* On ia64 if a page has been mapped somewhere as
* uncached, then it must also be accessed uncached
* by the kernel or data corruption may occur
*/
ptr = xlate_dev_mem_ptr(p);
if (!ptr)
return -EFAULT;
if (copy_to_user(buf, ptr, sz)) {
unxlate_dev_mem_ptr(p, ptr);
return