linux-IllusionX/drivers/char/mem.c
Linus Torvalds 4bb82551e1 Fix up mmap of /dev/kmem
This leaves the issue of whether we should deprecate the whole thing (or
if we should check the whole mmap range, for that matter) open. Just do
the minimal fix for now.
2005-08-13 14:22:59 -07:00

936 lines
21 KiB
C

/*
* 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/config.h>
#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/smp_lock.h>
#include <linux/devfs_fs_kernel.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 <asm/uaccess.h>
#include <asm/io.h>
#ifdef CONFIG_IA64
# include <linux/efi.h>
#endif
#if defined(CONFIG_S390_TAPE) && defined(CONFIG_S390_TAPE_CHAR)
extern void tapechar_init(void);
#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(__i386__)
/*
* On the PPro and successors, the MTRRs are used to set
* memory types for physical addresses outside main memory,
* so blindly setting PCD or PWT on those pages is wrong.
* For Pentiums and earlier, the surround logic should disable
* caching for the high addresses through the KEN pin, but
* we maintain the tradition of paranoia in this code.
*/
if (file->f_flags & O_SYNC)
return 1;
return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
&& addr >= __pa(high_memory);
#elif defined(__x86_64__)
/*
* This is broken because it can generate memory type aliases,
* which can cause cache corruptions
* But it is only available for root and we have to be bug-to-bug
* compatible with i386.
*/
if (file->f_flags & O_SYNC)
return 1;
/* same behaviour as i386. PAT always set to cached and MTRRs control the
caching behaviour.
Hopefully a full PAT implementation will fix that soon. */
return 0;
#elif defined(CONFIG_IA64)
/*
* On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
*/
return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
#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)
{
unsigned long end_mem;
end_mem = __pa(high_memory);
if (addr >= end_mem)
return 0;
if (*count > end_mem - addr)
*count = end_mem - addr;
return 1;
}
#endif
/*
* 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);
/*
* 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 (copy_to_user(buf, ptr, sz))
return -EFAULT;
buf += sz;
p += sz;
count -= sz;
read += sz;
}
*ppos += read;
return read;
}
static ssize_t write_mem(struct file * file, const char __user * buf,
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
ssize_t written, sz;
unsigned long copied;
void *ptr;
if (!valid_phys_addr_range(p, &count))
return -EFAULT;
written = 0;
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
/* we don't have page 0 mapped on sparc and m68k.. */
if (p < PAGE_SIZE) {
unsigned long sz = PAGE_SIZE - p;
if (sz > count)
sz = count;
/* Hmm. Do something? */
buf += sz;
p += sz;
count -= sz;
written += 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);
/*
* 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);
copied = copy_from_user(ptr, buf, sz);
if (copied) {
ssize_t ret;
ret = written + (sz - copied);
if (ret)
return ret;
return -EFAULT;
}
buf += sz;
p += sz;
count -= sz;
written += sz;
}
*ppos += written;
return written;
}
static int mmap_mem(struct file * file, struct vm_area_struct * vma)
{
#if defined(__HAVE_PHYS_MEM_ACCESS_PROT)
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
vma->vm_page_prot = phys_mem_access_prot(file, offset,
vma->vm_end - vma->vm_start,
vma->vm_page_prot);
#elif defined(pgprot_noncached)
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
int uncached;
uncached = uncached_access(file, offset);
if (uncached)
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
#endif
/* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
if (remap_pfn_range(vma,
vma->vm_start,
vma->vm_pgoff,
vma->vm_end-vma->vm_start,
vma->vm_page_prot))
return -EAGAIN;
return 0;
}
static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
{
unsigned long pfn;
/* Turn a kernel-virtual address into a physical page frame */
pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
/*
* RED-PEN: on some architectures there is more mapped memory
* than available in mem_map which pfn_valid checks
* for. Perhaps should add a new macro here.
*
* RED-PEN: vmalloc is not supported right now.
*/
if (!pfn_valid(pfn))
return -EIO;
vma->vm_pgoff = pfn;
return mmap_mem(file, vma);
}
#ifdef CONFIG_CRASH_DUMP
/*
* Read memory corresponding to the old kernel.
*/
static ssize_t read_oldmem(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
unsigned long pfn, offset;
size_t read = 0, csize;
int rc = 0;
while (count) {
pfn = *ppos / PAGE_SIZE;
if (pfn > saved_max_pfn)
return read;
offset = (unsigned long)(*ppos % PAGE_SIZE);
if (count > PAGE_SIZE - offset)
csize = PAGE_SIZE - offset;
else
csize = count;
rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
if (rc < 0)
return rc;
buf += csize;
*ppos += csize;
read += csize;
count -= csize;
}
return read;
}
#endif
extern long vread(char *buf, char *addr, unsigned long count);
extern long vwrite(char *buf, char *addr, unsigned long count);
/*
* This function reads the *virtual* memory as seen by the kernel.
*/
static ssize_t read_kmem(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
ssize_t low_count, read, sz;
char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
read = 0;
if (p < (unsigned long) high_memory) {
low_count = count;
if (count > (unsigned long) high_memory - p)
low_count = (unsigned long) high_memory - p;
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
/* we don't have page 0 mapped on sparc and m68k.. */
if (p < PAGE_SIZE && low_count > 0) {
size_t tmp = PAGE_SIZE - p;
if (tmp > low_count) tmp = low_count;
if (clear_user(buf, tmp))
return -EFAULT;
buf += tmp;
p += tmp;
read += tmp;
low_count -= tmp;
count -= tmp;
}
#endif
while (low_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, low_count);
/*
* 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
*/
kbuf = xlate_dev_kmem_ptr((char *)p);
if (copy_to_user(buf, kbuf, sz))
return -EFAULT;
buf += sz;
p += sz;
read += sz;
low_count -= sz;
count -= sz;
}
}
if (count > 0) {
kbuf = (char *)__get_free_page(GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
while (count > 0) {
int len = count;
if (len > PAGE_SIZE)
len = PAGE_SIZE;
len = vread(kbuf, (char *)p, len);
if (!len)
break;
if (copy_to_user(buf, kbuf, len)) {
free_page((unsigned long)kbuf);
return -EFAULT;
}
count -= len;
buf += len;
read += len;
p += len;
}
free_page((unsigned long)kbuf);
}
*ppos = p;
return read;
}
static inline ssize_t
do_write_kmem(void *p, unsigned long realp, const char __user * buf,
size_t count, loff_t *ppos)
{
ssize_t written, sz;
unsigned long copied;
written = 0;
#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
/* we don't have page 0 mapped on sparc and m68k.. */
if (realp < PAGE_SIZE) {
unsigned long sz = PAGE_SIZE - realp;
if (sz > count)
sz = count;
/* Hmm. Do something? */
buf += sz;
p += sz;
realp += sz;
count -= sz;
written += sz;
}
#endif
while (count > 0) {
char *ptr;
/*
* Handle first page in case it's not aligned
*/
if (-realp & (PAGE_SIZE - 1))
sz = -realp & (PAGE_SIZE - 1);
else
sz = PAGE_SIZE;
sz = min_t(unsigned long, sz, count);
/*
* 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_kmem_ptr(p);
copied = copy_from_user(ptr, buf, sz);
if (copied) {
ssize_t ret;
ret = written + (sz - copied);
if (ret)
return ret;
return -EFAULT;
}
buf += sz;
p += sz;
realp += sz;
count -= sz;
written += sz;
}
*ppos += written;
return written;
}
/*
* This function writes to the *virtual* memory as seen by the kernel.
*/
static ssize_t write_kmem(struct file * file, const char __user * buf,
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
ssize_t wrote = 0;
ssize_t virtr = 0;
ssize_t written;
char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
if (p < (unsigned long) high_memory) {
wrote = count;
if (count > (unsigned long) high_memory - p)
wrote = (unsigned long) high_memory - p;
written = do_write_kmem((void*)p, p, buf, wrote, ppos);
if (written != wrote)
return written;
wrote = written;
p += wrote;
buf += wrote;
count -= wrote;
}
if (count > 0) {
kbuf = (char *)__get_free_page(GFP_KERNEL);
if (!kbuf)
return wrote ? wrote : -ENOMEM;
while (count > 0) {
int len = count;
if (len > PAGE_SIZE)
len = PAGE_SIZE;
if (len) {
written = copy_from_user(kbuf, buf, len);
if (written) {
ssize_t ret;
free_page((unsigned long)kbuf);
ret = wrote + virtr + (len - written);
return ret ? ret : -EFAULT;
}
}
len = vwrite(kbuf, (char *)p, len);
count -= len;
buf += len;
virtr += len;
p += len;
}
free_page((unsigned long)kbuf);
}
*ppos = p;
return virtr + wrote;
}
#if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
static ssize_t read_port(struct file * file, char __user * buf,
size_t count, loff_t *ppos)
{
unsigned long i = *ppos;
char __user *tmp = buf;
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
while (count-- > 0 && i < 65536) {
if (__put_user(inb(i),tmp) < 0)
return -EFAULT;
i++;
tmp++;
}
*ppos = i;
return tmp-buf;
}
static ssize_t write_port(struct file * file, const char __user * buf,
size_t count, loff_t *ppos)
{
unsigned long i = *ppos;
const char __user * tmp = buf;
if (!access_ok(VERIFY_READ,buf,count))
return -EFAULT;
while (count-- > 0 && i < 65536) {
char c;
if (__get_user(c, tmp))
return -EFAULT;
outb(c,i);
i++;
tmp++;
}
*ppos = i;
return tmp-buf;
}
#endif
static ssize_t read_null(struct file * file, char __user * buf,
size_t count, loff_t *ppos)
{
return 0;
}
static ssize_t write_null(struct file * file, const char __user * buf,
size_t count, loff_t *ppos)
{
return count;
}
#ifdef CONFIG_MMU
/*
* For fun, we are using the MMU for this.
*/
static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
{
struct mm_struct *mm;
struct vm_area_struct * vma;
unsigned long addr=(unsigned long)buf;
mm = current->mm;
/* Oops, this was forgotten before. -ben */
down_read(&mm->mmap_sem);
/* For private mappings, just map in zero pages. */
for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
unsigned long count;
if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
goto out_up;
if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
break;
count = vma->vm_end - addr;
if (count > size)
count = size;
zap_page_range(vma, addr, count, NULL);
zeromap_page_range(vma, addr, count, PAGE_COPY);
size -= count;
buf += count;
addr += count;
if (size == 0)
goto out_up;
}
up_read(&mm->mmap_sem);
/* The shared case is hard. Let's do the conventional zeroing. */
do {
unsigned long unwritten = clear_user(buf, PAGE_SIZE);
if (unwritten)
return size + unwritten - PAGE_SIZE;
cond_resched();
buf += PAGE_SIZE;
size -= PAGE_SIZE;
} while (size);
return size;
out_up:
up_read(&mm->mmap_sem);
return size;
}
static ssize_t read_zero(struct file * file, char __user * buf,
size_t count, loff_t *ppos)
{
unsigned long left, unwritten, written = 0;
if (!count)
return 0;
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
left = count;
/* do we want to be clever? Arbitrary cut-off */
if (count >= PAGE_SIZE*4) {
unsigned long partial;
/* How much left of the page? */
partial = (PAGE_SIZE-1) & -(unsigned long) buf;
unwritten = clear_user(buf, partial);
written = partial - unwritten;
if (unwritten)
goto out;
left -= partial;
buf += partial;
unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
written += (left & PAGE_MASK) - unwritten;
if (unwritten)
goto out;
buf += left & PAGE_MASK;
left &= ~PAGE_MASK;
}
unwritten = clear_user(buf, left);
written += left - unwritten;
out:
return written ? written : -EFAULT;
}
static int mmap_zero(struct file * file, struct vm_area_struct * vma)
{
if (vma->vm_flags & VM_SHARED)
return shmem_zero_setup(vma);
if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
return -EAGAIN;
return 0;
}
#else /* CONFIG_MMU */
static ssize_t read_zero(struct file * file, char * buf,
size_t count, loff_t *ppos)
{
size_t todo = count;
while (todo) {
size_t chunk = todo;
if (chunk > 4096)
chunk = 4096; /* Just for latency reasons */
if (clear_user(buf, chunk))
return -EFAULT;
buf += chunk;
todo -= chunk;
cond_resched();
}
return count;
}
static int mmap_zero(struct file * file, struct vm_area_struct * vma)
{
return -ENOSYS;
}
#endif /* CONFIG_MMU */
static ssize_t write_full(struct file * file, const char __user * buf,
size_t count, loff_t *ppos)
{
return -ENOSPC;
}
/*
* Special lseek() function for /dev/null and /dev/zero. Most notably, you
* can fopen() both devices with "a" now. This was previously impossible.
* -- SRB.
*/
static loff_t null_lseek(struct file * file, loff_t offset, int orig)
{
return file->f_pos = 0;
}
/*
* The memory devices use the full 32/64 bits of the offset, and so we cannot
* check against negative addresses: they are ok. The return value is weird,
* though, in that case (0).
*
* also note that seeking relative to the "end of file" isn't supported:
* it has no meaning, so it returns -EINVAL.
*/
static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
{
loff_t ret;
down(&file->f_dentry->d_inode->i_sem);
switch (orig) {
case 0:
file->f_pos = offset;
ret = file->f_pos;
force_successful_syscall_return();
break;
case 1:
file->f_pos += offset;
ret = file->f_pos;
force_successful_syscall_return();
break;
default:
ret = -EINVAL;
}
up(&file->f_dentry->d_inode->i_sem);
return ret;
}
static int open_port(struct inode * inode, struct file * filp)
{
return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}
#define zero_lseek null_lseek
#define full_lseek null_lseek
#define write_zero write_null
#define read_full read_zero
#define open_mem open_port
#define open_kmem open_mem
#define open_oldmem open_mem
static struct file_operations mem_fops = {
.llseek = memory_lseek,
.read = read_mem,
.write = write_mem,
.mmap = mmap_mem,
.open = open_mem,
};
static struct file_operations kmem_fops = {
.llseek = memory_lseek,
.read = read_kmem,
.write = write_kmem,
.mmap = mmap_kmem,
.open = open_kmem,
};
static struct file_operations null_fops = {
.llseek = null_lseek,
.read = read_null,
.write = write_null,
};
#if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
static struct file_operations port_fops = {
.llseek = memory_lseek,
.read = read_port,
.write = write_port,
.open = open_port,
};
#endif
static struct file_operations zero_fops = {
.llseek = zero_lseek,
.read = read_zero,
.write = write_zero,
.mmap = mmap_zero,
};
static struct backing_dev_info zero_bdi = {
.capabilities = BDI_CAP_MAP_COPY,
};
static struct file_operations full_fops = {
.llseek = full_lseek,
.read = read_full,
.write = write_full,
};
#ifdef CONFIG_CRASH_DUMP
static struct file_operations oldmem_fops = {
.read = read_oldmem,
.open = open_oldmem,
};
#endif
static ssize_t kmsg_write(struct file * file, const char __user * buf,
size_t count, loff_t *ppos)
{
char *tmp;
int ret;
tmp = kmalloc(count + 1, GFP_KERNEL);
if (tmp == NULL)
return -ENOMEM;
ret = -EFAULT;
if (!copy_from_user(tmp, buf, count)) {
tmp[count] = 0;
ret = printk("%s", tmp);
}
kfree(tmp);
return ret;
}
static struct file_operations kmsg_fops = {
.write = kmsg_write,
};
static int memory_open(struct inode * inode, struct file * filp)
{
switch (iminor(inode)) {
case 1:
filp->f_op = &mem_fops;
break;
case 2:
filp->f_op = &kmem_fops;
break;
case 3:
filp->f_op = &null_fops;
break;
#if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
case 4:
filp->f_op = &port_fops;
break;
#endif
case 5:
filp->f_mapping->backing_dev_info = &zero_bdi;
filp->f_op = &zero_fops;
break;
case 7:
filp->f_op = &full_fops;
break;
case 8:
filp->f_op = &random_fops;
break;
case 9:
filp->f_op = &urandom_fops;
break;
case 11:
filp->f_op = &kmsg_fops;
break;
#ifdef CONFIG_CRASH_DUMP
case 12:
filp->f_op = &oldmem_fops;
break;
#endif
default:
return -ENXIO;
}
if (filp->f_op && filp->f_op->open)
return filp->f_op->open(inode,filp);
return 0;
}
static struct file_operations memory_fops = {
.open = memory_open, /* just a selector for the real open */
};
static const struct {
unsigned int minor;
char *name;
umode_t mode;
struct file_operations *fops;
} devlist[] = { /* list of minor devices */
{1, "mem", S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
{2, "kmem", S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
{3, "null", S_IRUGO | S_IWUGO, &null_fops},
#if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
{4, "port", S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
#endif
{5, "zero", S_IRUGO | S_IWUGO, &zero_fops},
{7, "full", S_IRUGO | S_IWUGO, &full_fops},
{8, "random", S_IRUGO | S_IWUSR, &random_fops},
{9, "urandom", S_IRUGO | S_IWUSR, &urandom_fops},
{11,"kmsg", S_IRUGO | S_IWUSR, &kmsg_fops},
#ifdef CONFIG_CRASH_DUMP
{12,"oldmem", S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
#endif
};
static struct class *mem_class;
static int __init chr_dev_init(void)
{
int i;
if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
printk("unable to get major %d for memory devs\n", MEM_MAJOR);
mem_class = class_create(THIS_MODULE, "mem");
for (i = 0; i < ARRAY_SIZE(devlist); i++) {
class_device_create(mem_class, MKDEV(MEM_MAJOR, devlist[i].minor),
NULL, devlist[i].name);
devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
S_IFCHR | devlist[i].mode, devlist[i].name);
}
return 0;
}
fs_initcall(chr_dev_init);