/* * 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/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/crash_dump.h> #include <linux/backing-dev.h> #include <linux/bootmem.h> #include <linux/splice.h> #include <linux/pfn.h> #include <asm/uaccess.h> #include <asm/io.h> #ifdef CONFIG_IA64 # include <linux/efi.h> #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_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_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) { if (addr + count > __pa(high_memory)) return 0; return 1; } static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) { 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) { written += sz - copied; if (written) break; return -EFAULT; } buf += sz; p += sz; count -= sz; written += sz; } *ppos += written; return written; } #ifndef __HAVE_PHYS_MEM_ACCESS_PROT static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { #ifdef pgprot_noncached unsigned long 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 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; vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, size, vma->vm_page_prot); /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */ if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, size, 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) { written += sz - copied; if (written) break; 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) { if (wrote + virtr) break; 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; } #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 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); } #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); if (zeromap_page_range(vma, addr, count, PAGE_COPY)) break; 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) { int err; if (vma->vm_flags & VM_SHARED) return shmem_zero_setup(vma); err = zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot); BUG_ON(err == -EEXIST); return err; } #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; mutex_lock(&file->f_path.dentry->d_inode->i_mutex); 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; } mutex_unlock(&file->f_path.dentry->d_inode->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 open_mem open_port #define open_kmem open_mem #define open_oldmem 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, }; 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, }; static const struct file_operations null_fops = { .llseek = null_lseek, .read = read_null, .write = 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, .mmap = mmap_zero, }; /* * capabilities for /dev/zero * - permits private mappings, "copies" are taken of the source of zeros */ static struct backing_dev_info zero_bdi = { .capabilities = BDI_CAP_MAP_COPY, }; static const struct file_operations full_fops = { .llseek = full_lseek, .read = read_full, .write = write_full, }; #ifdef CONFIG_CRASH_DUMP static const 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; ssize_t 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); if (ret > count) /* printk can add a prefix */ ret = count; } kfree(tmp); return ret; } static const 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; filp->f_mapping->backing_dev_info = &directly_mappable_cdev_bdi; break; case 2: filp->f_op = &kmem_fops; filp->f_mapping->backing_dev_info = &directly_mappable_cdev_bdi; break; case 3: filp->f_op = &null_fops; break; #ifdef CONFIG_DEVPORT 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 const 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; const 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}, #ifdef CONFIG_DEVPORT {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++) device_create(mem_class, NULL, MKDEV(MEM_MAJOR, devlist[i].minor), devlist[i].name); return 0; } fs_initcall(chr_dev_init);