mem.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 734 行 · 第 1/2 页

/*
 *  linux/drivers/char/mem.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Added devfs support. 
 *    Jan-11-1998, C. Scott Ananian <[e-mail]>
 *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <[e-mail]>
 */

#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 <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);
#elif defined(CONFIG_PPC64)
	/* On PPC64, we always do non-cacheable access to the IO hole and
	 * cacheable elsewhere. Cache paradox can checkstop the CPU and
	 * the high_memory heuristic below is wrong on machines with memory
	 * above the IO hole... Ah, and of course, XFree86 doesn't pass
	 * O_SYNC when mapping us to tap IO space. Surprised ?
	 */
	return !page_is_ram(addr >> PAGE_SHIFT);
#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

static ssize_t do_write_mem(void *p, unsigned long realp,
			    const char __user * buf, size_t count, loff_t *ppos)
{
	ssize_t written;
	unsigned long copied;

	written = 0;
#if defined(__sparc__) || (defined(__mc68000__) && defined(CONFIG_MMU))
	/* 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
	copied = copy_from_user(p, buf, count);
	if (copied) {
		ssize_t ret = written + (count - copied);

		if (ret)
			return ret;
		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 __user * buf,
			size_t count, loff_t *ppos)
{
	unsigned long p = *ppos;
	ssize_t read;

	if (!valid_phys_addr_range(p, &count))
		return -EFAULT;
	read = 0;
#if defined(__sparc__) || (defined(__mc68000__) && defined(CONFIG_MMU))
	/* 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 __user * buf, 
			 size_t count, loff_t *ppos)
{
	unsigned long p = *ppos;

	if (!valid_phys_addr_range(p, &count))
		return -EFAULT;
	return do_write_mem(__va(p), p, buf, count, ppos);
}

static int mmap_mem(struct file * file, struct vm_area_struct * vma)
{
	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
	int uncached;

	uncached = uncached_access(file, offset);
#ifdef pgprot_noncached
	if (uncached)
		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
#endif

	/* 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 (uncached)
		vma->vm_flags |= VM_IO;

	if (remap_page_range(vma, vma->vm_start, offset, vma->vm_end-vma->vm_start,
			     vma->vm_page_prot))
		return -EAGAIN;
	return 0;
}

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 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__) && defined(CONFIG_MMU))
		/* 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;
}

/*
 * 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_mem((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__)
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 (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 __user * buf,
			  size_t count, loff_t *ppos)
{
	unsigned long i = *ppos;
	const char __user * tmp = buf;