/* * 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 mmapping 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/backing-dev.h> #include <linux/bootmem.h> #include <linux/splice.h> #include <linux/pfn.h> #include <linux/export.h> #include <linux/io.h> #include <linux/aio.h> #include <asm/uaccess.h> #ifdef CONFIG_IA64 # include <linux/efi.h> #endif #define DEVPORT_MINOR 4 static inline unsigned long size_inside_page(unsigned long start, unsigned long size) { unsigned long sz; sz = PAGE_SIZE - (start & (PAGE_SIZE - 1)); return min(sz, size); } #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) { return addr + count <= __pa(high_memory); } 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 __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) { phys_addr_t 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 = size_inside_page(p, count); if (sz > 0) { if (clear_user(buf, sz)) return -EFAULT; buf += sz; p += sz; count -= sz; read += sz; } } #endif while (count > 0) { unsigned long remaining; sz = size_inside_page(p, 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; remaining = copy_to_user(buf, ptr, sz); unxlate_dev_mem_ptr(p, ptr); if (remaining) 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) { phys_addr_t 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) { sz = size_inside_page(p, count); /* Hmm. Do something? */ buf += sz; p += sz; count -= sz; written += sz; } #endif while (count > 0) { sz = size_inside_page(p, count); if (!range_is_allowed(p >> PAGE_SHIFT, sz)) 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) { if (written) break; return -EFAULT; } copied = copy_from_user(ptr, buf, sz); unxlate_dev_mem_ptr(p, ptr); if (copied) { written += sz - copied; if (written) break; return -EFAULT; } buf += sz; p += sz; count -= sz; written += sz; } *ppos += written; return written; } int __weak phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, unsigned long size, pgprot_t *vma_prot) { return 1; } #ifndef __HAVE_PHYS_MEM_ACCESS_PROT /* * Architectures vary in how they handle caching for addresses * outside of main memory. * */ #ifdef pgprot_noncached static int uncached_access(struct file *file, phys_addr_t addr) { #if defined(CONFIG_IA64) /* * On ia64, we ignore O_DSYNC 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_DSYNC will be done non-cached. */ if (file->f_flags & O_DSYNC) return 1; return addr >= __pa(high_memory); #endif } #endif static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { #ifdef pgprot_noncached phys_addr_t offset = pfn << PAGE_SHIFT; if (uncached_access(file, offset)) return pgprot_noncached(vma_prot); #endif return vma_prot; } #endif #ifndef CONFIG_MMU static unsigned long get_unmapped_area_mem(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { if (!valid_mmap_phys_addr_range(pgoff, len)) return (unsigned long) -EINVAL; return pgoff << PAGE_SHIFT; } /* can't do an in-place private mapping if there's no MMU */ static inline int private_mapping_ok(struct vm_area_struct *vma) { return vma->vm_flags & VM_MAYSHARE; } #else #define get_unmapped_area_mem NULL static inline int private_mapping_ok(struct vm_area_struct *vma) { return 1; } #endif static const struct vm_operations_struct mmap_mem_ops = { #ifdef CONFIG_HAVE_IOREMAP_PROT .access = generic_access_phys #endif }; static int mmap_mem(struct file *file, struct vm_area_struct *vma) { size_t size = vma->vm_end - vma->vm_start; if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) return -EINVAL; if (!private_mapping_ok(vma)) return -ENOSYS; if (!range_is_allowed(vma->vm_pgoff, size)) return -EPERM; if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, &vma->vm_page_prot)) return -EINVAL; vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, size, vma->vm_page_prot); vma->vm_ops = &mmap_mem_ops; /* Remap-pfn-range will mark the range VM_IO */ if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, size, vma->vm_page_prot)) { return -EAGAIN; } return 0; } #ifdef CONFIG_DEVKMEM 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); } #endif #ifdef CONFIG_DEVKMEM /* * 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 */ int err = 0; 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) { sz = size_inside_page(p, low_count); if (clear_user(buf, sz)) return -EFAULT; buf += sz; p += sz; read += sz; low_count -= sz; count -= sz; } #endif while (low_count > 0) { sz = size_inside_page(p, 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) { sz = size_inside_page(p, count); if (!is_vmalloc_or_module_addr((void *)p)) { err = -ENXIO; break; } sz = vread(kbuf, (char *)p, sz); if (!sz) break; if (copy_to_user(buf, kbuf, sz)) { err = -EFAULT; break; } count -= sz; buf += sz; read += sz; p += sz; } free_page((unsigned long)kbuf); } *ppos = p; return read ? read : err; } static ssize_t do_write_kmem(unsigned long p, 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 (p < PAGE_SIZE) { sz = size_inside_page(p, count); /* Hmm. Do something? */ buf += sz; p += sz; count -= sz; written += sz; } #endif while (count > 0) { char *ptr; sz = size_inside_page(p, 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((char *)p); copied = copy_from_user(ptr, buf, sz); if (copied) { written += sz - copied; if (written) break; return -EFAULT; } buf += sz; p += 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; char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p); wrote = do_write_kmem(p, buf, to_write, ppos); if (wrote != to_write) return wrote; 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) { unsigned long sz = size_inside_page(p, count); unsigned long n; if (!is_vmalloc_or_module_addr((void *)p)) { err = -ENXIO; break; } n = copy_from_user(kbuf, buf, sz); if (n) { err = -EFAULT; break; } vwrite(kbuf, (char *)p, sz); count -= sz; buf += sz; virtr += sz; p += sz; } free_page((unsigned long)kbuf); } *ppos = p; return virtr + wrote ? : err; } #endif #ifdef CONFIG_DEVPORT 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)) { if (tmp > buf) break; 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; } static ssize_t aio_read_null(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t pos) { return 0; } static ssize_t aio_write_null(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t pos) { return iov_length(iov, nr_segs); } static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, struct splice_desc *sd) { return sd->len; } static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, loff_t *ppos, size_t len, unsigned int flags) { return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); } static ssize_t read_zero(struct file *file, char __user *buf, size_t count, loff_t *ppos) { size_t written; if (!count) return 0; if (!access_ok(VERIFY_WRITE, buf, count)) return -EFAULT; written = 0; while (count) { unsigned long unwritten; size_t chunk = count; if (chunk > PAGE_SIZE) chunk = PAGE_SIZE; /* Just for latency reasons */ unwritten = __clear_user(buf, chunk); written += chunk - unwritten; if (unwritten) break; if (signal_pending(current)) return written ? written : -ERESTARTSYS; buf += chunk; count -= chunk; cond_resched(); } return written ? written : -EFAULT; } static ssize_t aio_read_zero(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t pos) { size_t written = 0; unsigned long i; ssize_t ret; for (i = 0; i < nr_segs; i++) { ret = read_zero(iocb->ki_filp, iov[i].iov_base, iov[i].iov_len, &pos); if (ret < 0) break; written += ret; } return written ? written : -EFAULT; } static int mmap_zero(struct file *file, struct vm_area_struct *vma) { #ifndef CONFIG_MMU return -ENOSYS; #endif if (vma->vm_flags & VM_SHARED) return shmem_zero_setup(vma); return 0; } 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; mutex_lock(&file_inode(file)->i_mutex); switch (orig) { case SEEK_CUR: offset += file->f_pos; case SEEK_SET: /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ if (IS_ERR_VALUE((unsigned long long)offset)) { ret = -EOVERFLOW; break; } file->f_pos = offset; ret = file->f_pos; force_successful_syscall_return(); break; default: ret = -EINVAL; } mutex_unlock(&file_inode(file)->i_mutex); 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 aio_write_zero aio_write_null #define open_mem open_port #define open_kmem open_mem static const struct file_operations mem_fops = { .llseek = memory_lseek, .read = read_mem, .write = write_mem, .mmap = mmap_mem, .open = open_mem, .get_unmapped_area = get_unmapped_area_mem, }; #ifdef CONFIG_DEVKMEM static const struct file_operations kmem_fops = { .llseek = memory_lseek, .read = read_kmem, .write = write_kmem, .mmap = mmap_kmem, .open = open_kmem, .get_unmapped_area = get_unmapped_area_mem, }; #endif static const struct file_operations null_fops = { .llseek = null_lseek, .read = read_null, .write = write_null, .aio_read = aio_read_null, .aio_write = aio_write_null, .splice_write = splice_write_null, }; #ifdef CONFIG_DEVPORT static const struct file_operations port_fops = { .llseek = memory_lseek, .read = read_port, .write = write_port, .open = open_port, }; #endif static const struct file_operations zero_fops = { .llseek = zero_lseek, .read = read_zero, .write = write_zero, .aio_read = aio_read_zero, .aio_write = aio_write_zero, .mmap = mmap_zero, }; /* * capabilities for /dev/zero * - permits private mappings, "copies" are taken of the source of zeros * - no writeback happens */ static struct backing_dev_info zero_bdi = { .name = "char/mem", .capabilities = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK, }; static const struct file_operations full_fops = { .llseek = full_lseek, .read = read_full, .write = write_full, }; static const struct memdev { const char *name; umode_t mode; const struct file_operations *fops; struct backing_dev_info *dev_info; } devlist[] = { [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi }, #ifdef CONFIG_DEVKMEM [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi }, #endif [3] = { "null", 0666, &null_fops, NULL }, #ifdef CONFIG_DEVPORT [4] = { "port", 0, &port_fops, NULL }, #endif [5] = { "zero", 0666, &zero_fops, &zero_bdi }, [7] = { "full", 0666, &full_fops, NULL }, [8] = { "random", 0666, &random_fops, NULL }, [9] = { "urandom", 0666, &urandom_fops, NULL }, #ifdef CONFIG_PRINTK [11] = { "kmsg", 0644, &kmsg_fops, NULL }, #endif }; static int memory_open(struct inode *inode, struct file *filp) { int minor; const struct memdev *dev; minor = iminor(inode); if (minor >= ARRAY_SIZE(devlist)) return -ENXIO; dev = &devlist[minor]; if (!dev->fops) return -ENXIO; filp->f_op = dev->fops; if (dev->dev_info) filp->f_mapping->backing_dev_info = dev->dev_info; /* Is /dev/mem or /dev/kmem ? */ if (dev->dev_info == &directly_mappable_cdev_bdi) filp->f_mode |= FMODE_UNSIGNED_OFFSET; if (dev->fops->open) return dev->fops->open(inode, filp); return 0; } static const struct file_operations memory_fops = { .open = memory_open, .llseek = noop_llseek, }; static char *mem_devnode(struct device *dev, umode_t *mode) { if (mode && devlist[MINOR(dev->devt)].mode) *mode = devlist[MINOR(dev->devt)].mode; return NULL; } static struct class *mem_class; static int __init chr_dev_init(void) { int minor; int err; err = bdi_init(&zero_bdi); if (err) return err; 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"); if (IS_ERR(mem_class)) return PTR_ERR(mem_class); mem_class->devnode = mem_devnode; for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { if (!devlist[minor].name) continue; /* * Create /dev/port? */ if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) continue; device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), NULL, devlist[minor].name); } return tty_init(); } fs_initcall(chr_dev_init);