blob: 9b934ed20368552f5f30d64f303d4e30a9f9824c [file] [log] [blame]
/*
* 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/tpqic02.h>
#include <linux/ftape.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 <asm/uaccess.h>
#include <asm/io.h>
#include <asm/pgalloc.h>
#ifdef CONFIG_I2C
extern int i2c_init_all(void);
#endif
#ifdef CONFIG_FB
extern void fbmem_init(void);
#endif
#ifdef CONFIG_PROM_CONSOLE
extern void prom_con_init(void);
#endif
#ifdef CONFIG_MDA_CONSOLE
extern void mda_console_init(void);
#endif
#if defined(CONFIG_S390_TAPE) && defined(CONFIG_S390_TAPE_CHAR)
extern void tapechar_init(void);
#endif
static ssize_t do_write_mem(struct file * file, void *p, unsigned long realp,
const char * buf, size_t count, loff_t *ppos)
{
ssize_t written;
written = 0;
#if defined(__sparc__) || defined(__mc68000__)
/* 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;
count-=sz;
written+=sz;
}
#endif
if (copy_from_user(p, buf, count))
return -EFAULT;
written += count;
*ppos += written;
return written;
}
/*
* This funcion reads the *physical* memory. The f_pos points directly to the
* memory location.
*/
static ssize_t read_mem(struct file * file, char * buf,
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
unsigned long end_mem;
ssize_t read;
end_mem = __pa(high_memory);
if (p >= end_mem)
return 0;
if (count > end_mem - p)
count = end_mem - p;
read = 0;
#if defined(__sparc__) || defined(__mc68000__)
/* 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;
if (sz > 0) {
if (clear_user(buf, sz))
return -EFAULT;
buf += sz;
p += sz;
count -= sz;
read += sz;
}
}
#endif
if (copy_to_user(buf, __va(p), count))
return -EFAULT;
read += count;
*ppos += read;
return read;
}
static ssize_t write_mem(struct file * file, const char * buf,
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
unsigned long end_mem;
end_mem = __pa(high_memory);
if (p >= end_mem)
return 0;
if (count > end_mem - p)
count = end_mem - p;
return do_write_mem(file, __va(p), p, buf, count, ppos);
}
#ifndef pgprot_noncached
/*
* This should probably be per-architecture in <asm/pgtable.h>
*/
static inline pgprot_t pgprot_noncached(pgprot_t _prot)
{
unsigned long prot = pgprot_val(_prot);
#if defined(__i386__) || defined(__x86_64__)
/* On PPro and successors, PCD alone doesn't always mean
uncached because of interactions with the MTRRs. PCD | PWT
means definitely uncached. */
if (boot_cpu_data.x86 > 3)
prot |= _PAGE_PCD | _PAGE_PWT;
#elif defined(__powerpc__)
prot |= _PAGE_NO_CACHE | _PAGE_GUARDED;
#elif defined(__mc68000__)
#ifdef SUN3_PAGE_NOCACHE
if (MMU_IS_SUN3)
prot |= SUN3_PAGE_NOCACHE;
else
#endif
if (MMU_IS_851 || MMU_IS_030)
prot |= _PAGE_NOCACHE030;
/* Use no-cache mode, serialized */
else if (MMU_IS_040 || MMU_IS_060)
prot = (prot & _CACHEMASK040) | _PAGE_NOCACHE_S;
#endif
return __pgprot(prot);
}
#endif /* !pgprot_noncached */
/*
* Architectures vary in how they handle caching for addresses
* outside of main memory.
*/
static inline int noncached_address(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.
*/
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);
#else
return addr >= __pa(high_memory);
#endif
}
static int mmap_mem(struct file * file, struct vm_area_struct * vma)
{
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
/*
* 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 (noncached_address(offset) || (file->f_flags & O_SYNC))
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
/* Don't try to swap out physical pages.. */
vma->vm_flags |= VM_RESERVED;
/*
* Don't dump addresses that are not real memory to a core file.
*/
if (offset >= __pa(high_memory) || (file->f_flags & O_SYNC))
vma->vm_flags |= VM_IO;
if (remap_page_range(vma->vm_start, offset, vma->vm_end-vma->vm_start,
vma->vm_page_prot))
return -EAGAIN;
return 0;
}
/*
* This function reads the *virtual* memory as seen by the kernel.
*/
static ssize_t read_kmem(struct file *file, char *buf,
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
ssize_t read = 0;
ssize_t virtr = 0;
char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
if (p < (unsigned long) high_memory) {
read = count;
if (count > (unsigned long) high_memory - p)
read = (unsigned long) high_memory - p;
#if defined(__sparc__) || defined(__mc68000__)
/* we don't have page 0 mapped on sparc and m68k.. */
if (p < PAGE_SIZE && read > 0) {
size_t tmp = PAGE_SIZE - p;
if (tmp > read) tmp = read;
if (clear_user(buf, tmp))
return -EFAULT;
buf += tmp;
p += tmp;
read -= tmp;
count -= tmp;
}
#endif
if (copy_to_user(buf, (char *)p, read))
return -EFAULT;
p += read;
buf += read;
count -= read;
}
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;
virtr += len;
p += len;
}
free_page((unsigned long)kbuf);
}
*ppos = p;
return virtr + read;
}
extern long vwrite(char *buf, char *addr, unsigned long count);
/*
* This function writes to the *virtual* memory as seen by the kernel.
*/
static ssize_t write_kmem(struct file * file, const char * buf,
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
ssize_t wrote = 0;
ssize_t virtr = 0;
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;
wrote = do_write_mem(file, (void*)p, p, buf, wrote, ppos);
if(wrote < 0)
return(wrote);
p += wrote;
buf += wrote;
count -= wrote;
}
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;
if (len && copy_from_user(kbuf, buf, len)) {
free_page((unsigned long)kbuf);
return -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__)
static ssize_t read_port(struct file * file, char * buf,
size_t count, loff_t *ppos)
{
unsigned long i = *ppos;
char *tmp = buf;
if (verify_area(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 * buf,
size_t count, loff_t *ppos)
{
unsigned long i = *ppos;
const char * tmp = buf;
if (verify_area(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 * buf,
size_t count, loff_t *ppos)
{
return 0;
}
static ssize_t write_null(struct file * file, const char * buf,
size_t count, loff_t *ppos)
{
return count;
}
/*
* For fun, we are using the MMU for this.
*/
static inline size_t read_zero_pagealigned(char * 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)
break;
count = vma->vm_end - addr;
if (count > size)
count = size;
zap_page_range(mm, addr, count);
zeromap_page_range(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;
if (current->need_resched)
schedule();
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 * 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->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
return -EAGAIN;
return 0;
}
static ssize_t write_full(struct file * file, const char * 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;
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;
}
return ret;
}
static int open_port(struct inode * inode, struct file * filp)
{
return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}
struct page *kmem_vm_nopage(struct vm_area_struct *vma, unsigned long address, int write)
{
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
unsigned long kaddr;
pgd_t *pgd;
pmd_t *pmd;
pte_t *ptep, pte;
struct page *page = NULL;
/* address is user VA; convert to kernel VA of desired page */
kaddr = (address - vma->vm_start) + offset;
kaddr = VMALLOC_VMADDR(kaddr);
spin_lock(&init_mm.page_table_lock);
/* Lookup page structure for kernel VA */
pgd = pgd_offset(&init_mm, kaddr);
if (pgd_none(*pgd) || pgd_bad(*pgd))
goto out;
pmd = pmd_offset(pgd, kaddr);
if (pmd_none(*pmd) || pmd_bad(*pmd))
goto out;
ptep = pte_offset(pmd, kaddr);
if (!ptep)
goto out;
pte = *ptep;
if (!pte_present(pte))
goto out;
if (write && !pte_write(pte))
goto out;
page = pte_page(pte);
if (!VALID_PAGE(page)) {
page = NULL;
goto out;
}
/* Increment reference count on page */
get_page(page);
out:
spin_unlock(&init_mm.page_table_lock);
return page;
}
struct vm_operations_struct kmem_vm_ops = {
nopage: kmem_vm_nopage,
};
static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
{
unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
unsigned long size = vma->vm_end - vma->vm_start;
/*
* If the user is not attempting to mmap a high memory address then
* the standard mmap_mem mechanism will work. High memory addresses
* need special handling, as remap_page_range expects a physically-
* contiguous range of kernel addresses (such as obtained in kmalloc).
*/
if ((offset + size) < (unsigned long) high_memory)
return mmap_mem(file, vma);
/*
* 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 (noncached_address(offset) || (file->f_flags & O_SYNC))
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
/* Don't do anything here; "nopage" will fill the holes */
vma->vm_ops = &kmem_vm_ops;
/* Don't try to swap out physical pages.. */
vma->vm_flags |= VM_RESERVED;
/*
* Don't dump addresses that are not real memory to a core file.
*/
vma->vm_flags |= VM_IO;
return 0;
}
#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
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__)
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 file_operations full_fops = {
llseek: full_lseek,
read: read_full,
write: write_full,
};
extern struct file_operations anon_file_operations;
static int memory_open(struct inode * inode, struct file * filp)
{
switch (MINOR(inode->i_rdev)) {
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__)
case 4:
filp->f_op = &port_fops;
break;
#endif
case 5:
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 10:
filp->f_op = &anon_file_operations;
break;
default:
return -ENXIO;
}
if (filp->f_op && filp->f_op->open)
return filp->f_op->open(inode,filp);
return 0;
}
void __init memory_devfs_register (void)
{
/* These are never unregistered */
static const struct {
unsigned short minor;
char *name;
umode_t mode;
struct file_operations *fops;
} list[] = { /* 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__)
{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},
{10, "anon", S_IRUGO | S_IWUSR, &anon_file_operations},
};
int i;
for (i=0; i<(sizeof(list)/sizeof(*list)); i++)
devfs_register (NULL, list[i].name, DEVFS_FL_NONE,
MEM_MAJOR, list[i].minor,
list[i].mode | S_IFCHR,
list[i].fops, NULL);
}
static struct file_operations memory_fops = {
open: memory_open, /* just a selector for the real open */
};
int __init chr_dev_init(void)
{
if (devfs_register_chrdev(MEM_MAJOR,"mem",&memory_fops))
printk("unable to get major %d for memory devs\n", MEM_MAJOR);
memory_devfs_register();
rand_initialize();
#ifdef CONFIG_I2C
i2c_init_all();
#endif
#if defined (CONFIG_FB)
fbmem_init();
#endif
#if defined (CONFIG_PROM_CONSOLE)
prom_con_init();
#endif
#if defined (CONFIG_MDA_CONSOLE)
mda_console_init();
#endif
tty_init();
#ifdef CONFIG_M68K_PRINTER
lp_m68k_init();
#endif
misc_init();
#if CONFIG_QIC02_TAPE
qic02_tape_init();
#endif
#ifdef CONFIG_FTAPE
ftape_init();
#endif
#if defined(CONFIG_S390_TAPE) && defined(CONFIG_S390_TAPE_CHAR)
tapechar_init();
#endif
return 0;
}
__initcall(chr_dev_init);