diff options
Diffstat (limited to 'drivers/char/mem.c')
| -rw-r--r-- | drivers/char/mem.c | 880 |
1 files changed, 880 insertions, 0 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c new file mode 100644 index 000000000000..947cb3cef816 --- /dev/null +++ b/drivers/char/mem.c @@ -0,0 +1,880 @@ +/* + * 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/backing-dev.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 long val; + /* + * 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(vma->vm_pgoff)) + return -EIO; + val = (u64)vma->vm_pgoff << PAGE_SHIFT; + vma->vm_pgoff = __pa(val) >> PAGE_SHIFT; + return mmap_mem(file, vma); +} + +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__) +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 + +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 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, +}; + +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__) + 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; + 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__) + {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}, +}; + +static struct class_simple *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_simple_create(THIS_MODULE, "mem"); + for (i = 0; i < ARRAY_SIZE(devlist); i++) { + class_simple_device_add(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); |