linux/drivers/char/mem.c
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   1/*
   2 *  linux/drivers/char/mem.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 *
   6 *  Added devfs support.
   7 *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
   8 *  Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
   9 */
  10
  11#include <linux/mm.h>
  12#include <linux/miscdevice.h>
  13#include <linux/slab.h>
  14#include <linux/vmalloc.h>
  15#include <linux/mman.h>
  16#include <linux/random.h>
  17#include <linux/init.h>
  18#include <linux/raw.h>
  19#include <linux/tty.h>
  20#include <linux/capability.h>
  21#include <linux/ptrace.h>
  22#include <linux/device.h>
  23#include <linux/highmem.h>
  24#include <linux/backing-dev.h>
  25#include <linux/splice.h>
  26#include <linux/pfn.h>
  27#include <linux/export.h>
  28#include <linux/io.h>
  29#include <linux/aio.h>
  30
  31#include <asm/uaccess.h>
  32
  33#ifdef CONFIG_IA64
  34# include <linux/efi.h>
  35#endif
  36
  37#define DEVPORT_MINOR   4
  38
  39static inline unsigned long size_inside_page(unsigned long start,
  40                                             unsigned long size)
  41{
  42        unsigned long sz;
  43
  44        sz = PAGE_SIZE - (start & (PAGE_SIZE - 1));
  45
  46        return min(sz, size);
  47}
  48
  49#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
  50static inline int valid_phys_addr_range(phys_addr_t addr, size_t count)
  51{
  52        return addr + count <= __pa(high_memory);
  53}
  54
  55static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
  56{
  57        return 1;
  58}
  59#endif
  60
  61#ifdef CONFIG_STRICT_DEVMEM
  62static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  63{
  64        u64 from = ((u64)pfn) << PAGE_SHIFT;
  65        u64 to = from + size;
  66        u64 cursor = from;
  67
  68        while (cursor < to) {
  69                if (!devmem_is_allowed(pfn)) {
  70                        printk(KERN_INFO
  71                "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
  72                                current->comm, from, to);
  73                        return 0;
  74                }
  75                cursor += PAGE_SIZE;
  76                pfn++;
  77        }
  78        return 1;
  79}
  80#else
  81static inline int range_is_allowed(unsigned long pfn, unsigned long size)
  82{
  83        return 1;
  84}
  85#endif
  86
  87#ifndef unxlate_dev_mem_ptr
  88#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
  89void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr)
  90{
  91}
  92#endif
  93
  94/*
  95 * This funcion reads the *physical* memory. The f_pos points directly to the
  96 * memory location.
  97 */
  98static ssize_t read_mem(struct file *file, char __user *buf,
  99                        size_t count, loff_t *ppos)
 100{
 101        phys_addr_t p = *ppos;
 102        ssize_t read, sz;
 103        void *ptr;
 104
 105        if (p != *ppos)
 106                return 0;
 107
 108        if (!valid_phys_addr_range(p, count))
 109                return -EFAULT;
 110        read = 0;
 111#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 112        /* we don't have page 0 mapped on sparc and m68k.. */
 113        if (p < PAGE_SIZE) {
 114                sz = size_inside_page(p, count);
 115                if (sz > 0) {
 116                        if (clear_user(buf, sz))
 117                                return -EFAULT;
 118                        buf += sz;
 119                        p += sz;
 120                        count -= sz;
 121                        read += sz;
 122                }
 123        }
 124#endif
 125
 126        while (count > 0) {
 127                unsigned long remaining;
 128
 129                sz = size_inside_page(p, count);
 130
 131                if (!range_is_allowed(p >> PAGE_SHIFT, count))
 132                        return -EPERM;
 133
 134                /*
 135                 * On ia64 if a page has been mapped somewhere as uncached, then
 136                 * it must also be accessed uncached by the kernel or data
 137                 * corruption may occur.
 138                 */
 139                ptr = xlate_dev_mem_ptr(p);
 140                if (!ptr)
 141                        return -EFAULT;
 142
 143                remaining = copy_to_user(buf, ptr, sz);
 144                unxlate_dev_mem_ptr(p, ptr);
 145                if (remaining)
 146                        return -EFAULT;
 147
 148                buf += sz;
 149                p += sz;
 150                count -= sz;
 151                read += sz;
 152        }
 153
 154        *ppos += read;
 155        return read;
 156}
 157
 158static ssize_t write_mem(struct file *file, const char __user *buf,
 159                         size_t count, loff_t *ppos)
 160{
 161        phys_addr_t p = *ppos;
 162        ssize_t written, sz;
 163        unsigned long copied;
 164        void *ptr;
 165
 166        if (p != *ppos)
 167                return -EFBIG;
 168
 169        if (!valid_phys_addr_range(p, count))
 170                return -EFAULT;
 171
 172        written = 0;
 173
 174#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 175        /* we don't have page 0 mapped on sparc and m68k.. */
 176        if (p < PAGE_SIZE) {
 177                sz = size_inside_page(p, count);
 178                /* Hmm. Do something? */
 179                buf += sz;
 180                p += sz;
 181                count -= sz;
 182                written += sz;
 183        }
 184#endif
 185
 186        while (count > 0) {
 187                sz = size_inside_page(p, count);
 188
 189                if (!range_is_allowed(p >> PAGE_SHIFT, sz))
 190                        return -EPERM;
 191
 192                /*
 193                 * On ia64 if a page has been mapped somewhere as uncached, then
 194                 * it must also be accessed uncached by the kernel or data
 195                 * corruption may occur.
 196                 */
 197                ptr = xlate_dev_mem_ptr(p);
 198                if (!ptr) {
 199                        if (written)
 200                                break;
 201                        return -EFAULT;
 202                }
 203
 204                copied = copy_from_user(ptr, buf, sz);
 205                unxlate_dev_mem_ptr(p, ptr);
 206                if (copied) {
 207                        written += sz - copied;
 208                        if (written)
 209                                break;
 210                        return -EFAULT;
 211                }
 212
 213                buf += sz;
 214                p += sz;
 215                count -= sz;
 216                written += sz;
 217        }
 218
 219        *ppos += written;
 220        return written;
 221}
 222
 223int __weak phys_mem_access_prot_allowed(struct file *file,
 224        unsigned long pfn, unsigned long size, pgprot_t *vma_prot)
 225{
 226        return 1;
 227}
 228
 229#ifndef __HAVE_PHYS_MEM_ACCESS_PROT
 230
 231/*
 232 * Architectures vary in how they handle caching for addresses
 233 * outside of main memory.
 234 *
 235 */
 236#ifdef pgprot_noncached
 237static int uncached_access(struct file *file, phys_addr_t addr)
 238{
 239#if defined(CONFIG_IA64)
 240        /*
 241         * On ia64, we ignore O_DSYNC because we cannot tolerate memory
 242         * attribute aliases.
 243         */
 244        return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
 245#elif defined(CONFIG_MIPS)
 246        {
 247                extern int __uncached_access(struct file *file,
 248                                             unsigned long addr);
 249
 250                return __uncached_access(file, addr);
 251        }
 252#else
 253        /*
 254         * Accessing memory above the top the kernel knows about or through a
 255         * file pointer
 256         * that was marked O_DSYNC will be done non-cached.
 257         */
 258        if (file->f_flags & O_DSYNC)
 259                return 1;
 260        return addr >= __pa(high_memory);
 261#endif
 262}
 263#endif
 264
 265static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 266                                     unsigned long size, pgprot_t vma_prot)
 267{
 268#ifdef pgprot_noncached
 269        phys_addr_t offset = pfn << PAGE_SHIFT;
 270
 271        if (uncached_access(file, offset))
 272                return pgprot_noncached(vma_prot);
 273#endif
 274        return vma_prot;
 275}
 276#endif
 277
 278#ifndef CONFIG_MMU
 279static unsigned long get_unmapped_area_mem(struct file *file,
 280                                           unsigned long addr,
 281                                           unsigned long len,
 282                                           unsigned long pgoff,
 283                                           unsigned long flags)
 284{
 285        if (!valid_mmap_phys_addr_range(pgoff, len))
 286                return (unsigned long) -EINVAL;
 287        return pgoff << PAGE_SHIFT;
 288}
 289
 290/* can't do an in-place private mapping if there's no MMU */
 291static inline int private_mapping_ok(struct vm_area_struct *vma)
 292{
 293        return vma->vm_flags & VM_MAYSHARE;
 294}
 295#else
 296#define get_unmapped_area_mem   NULL
 297
 298static inline int private_mapping_ok(struct vm_area_struct *vma)
 299{
 300        return 1;
 301}
 302#endif
 303
 304static const struct vm_operations_struct mmap_mem_ops = {
 305#ifdef CONFIG_HAVE_IOREMAP_PROT
 306        .access = generic_access_phys
 307#endif
 308};
 309
 310static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 311{
 312        size_t size = vma->vm_end - vma->vm_start;
 313
 314        if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))
 315                return -EINVAL;
 316
 317        if (!private_mapping_ok(vma))
 318                return -ENOSYS;
 319
 320        if (!range_is_allowed(vma->vm_pgoff, size))
 321                return -EPERM;
 322
 323        if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size,
 324                                                &vma->vm_page_prot))
 325                return -EINVAL;
 326
 327        vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
 328                                                 size,
 329                                                 vma->vm_page_prot);
 330
 331        vma->vm_ops = &mmap_mem_ops;
 332
 333        /* Remap-pfn-range will mark the range VM_IO */
 334        if (remap_pfn_range(vma,
 335                            vma->vm_start,
 336                            vma->vm_pgoff,
 337                            size,
 338                            vma->vm_page_prot)) {
 339                return -EAGAIN;
 340        }
 341        return 0;
 342}
 343
 344#ifdef CONFIG_DEVKMEM
 345static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 346{
 347        unsigned long pfn;
 348
 349        /* Turn a kernel-virtual address into a physical page frame */
 350        pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
 351
 352        /*
 353         * RED-PEN: on some architectures there is more mapped memory than
 354         * available in mem_map which pfn_valid checks for. Perhaps should add a
 355         * new macro here.
 356         *
 357         * RED-PEN: vmalloc is not supported right now.
 358         */
 359        if (!pfn_valid(pfn))
 360                return -EIO;
 361
 362        vma->vm_pgoff = pfn;
 363        return mmap_mem(file, vma);
 364}
 365#endif
 366
 367#ifdef CONFIG_DEVKMEM
 368/*
 369 * This function reads the *virtual* memory as seen by the kernel.
 370 */
 371static ssize_t read_kmem(struct file *file, char __user *buf,
 372                         size_t count, loff_t *ppos)
 373{
 374        unsigned long p = *ppos;
 375        ssize_t low_count, read, sz;
 376        char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
 377        int err = 0;
 378
 379        read = 0;
 380        if (p < (unsigned long) high_memory) {
 381                low_count = count;
 382                if (count > (unsigned long)high_memory - p)
 383                        low_count = (unsigned long)high_memory - p;
 384
 385#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 386                /* we don't have page 0 mapped on sparc and m68k.. */
 387                if (p < PAGE_SIZE && low_count > 0) {
 388                        sz = size_inside_page(p, low_count);
 389                        if (clear_user(buf, sz))
 390                                return -EFAULT;
 391                        buf += sz;
 392                        p += sz;
 393                        read += sz;
 394                        low_count -= sz;
 395                        count -= sz;
 396                }
 397#endif
 398                while (low_count > 0) {
 399                        sz = size_inside_page(p, low_count);
 400
 401                        /*
 402                         * On ia64 if a page has been mapped somewhere as
 403                         * uncached, then it must also be accessed uncached
 404                         * by the kernel or data corruption may occur
 405                         */
 406                        kbuf = xlate_dev_kmem_ptr((void *)p);
 407
 408                        if (copy_to_user(buf, kbuf, sz))
 409                                return -EFAULT;
 410                        buf += sz;
 411                        p += sz;
 412                        read += sz;
 413                        low_count -= sz;
 414                        count -= sz;
 415                }
 416        }
 417
 418        if (count > 0) {
 419                kbuf = (char *)__get_free_page(GFP_KERNEL);
 420                if (!kbuf)
 421                        return -ENOMEM;
 422                while (count > 0) {
 423                        sz = size_inside_page(p, count);
 424                        if (!is_vmalloc_or_module_addr((void *)p)) {
 425                                err = -ENXIO;
 426                                break;
 427                        }
 428                        sz = vread(kbuf, (char *)p, sz);
 429                        if (!sz)
 430                                break;
 431                        if (copy_to_user(buf, kbuf, sz)) {
 432                                err = -EFAULT;
 433                                break;
 434                        }
 435                        count -= sz;
 436                        buf += sz;
 437                        read += sz;
 438                        p += sz;
 439                }
 440                free_page((unsigned long)kbuf);
 441        }
 442        *ppos = p;
 443        return read ? read : err;
 444}
 445
 446
 447static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
 448                                size_t count, loff_t *ppos)
 449{
 450        ssize_t written, sz;
 451        unsigned long copied;
 452
 453        written = 0;
 454#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
 455        /* we don't have page 0 mapped on sparc and m68k.. */
 456        if (p < PAGE_SIZE) {
 457                sz = size_inside_page(p, count);
 458                /* Hmm. Do something? */
 459                buf += sz;
 460                p += sz;
 461                count -= sz;
 462                written += sz;
 463        }
 464#endif
 465
 466        while (count > 0) {
 467                void *ptr;
 468
 469                sz = size_inside_page(p, count);
 470
 471                /*
 472                 * On ia64 if a page has been mapped somewhere as uncached, then
 473                 * it must also be accessed uncached by the kernel or data
 474                 * corruption may occur.
 475                 */
 476                ptr = xlate_dev_kmem_ptr((void *)p);
 477
 478                copied = copy_from_user(ptr, buf, sz);
 479                if (copied) {
 480                        written += sz - copied;
 481                        if (written)
 482                                break;
 483                        return -EFAULT;
 484                }
 485                buf += sz;
 486                p += sz;
 487                count -= sz;
 488                written += sz;
 489        }
 490
 491        *ppos += written;
 492        return written;
 493}
 494
 495/*
 496 * This function writes to the *virtual* memory as seen by the kernel.
 497 */
 498static ssize_t write_kmem(struct file *file, const char __user *buf,
 499                          size_t count, loff_t *ppos)
 500{
 501        unsigned long p = *ppos;
 502        ssize_t wrote = 0;
 503        ssize_t virtr = 0;
 504        char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
 505        int err = 0;
 506
 507        if (p < (unsigned long) high_memory) {
 508                unsigned long to_write = min_t(unsigned long, count,
 509                                               (unsigned long)high_memory - p);
 510                wrote = do_write_kmem(p, buf, to_write, ppos);
 511                if (wrote != to_write)
 512                        return wrote;
 513                p += wrote;
 514                buf += wrote;
 515                count -= wrote;
 516        }
 517
 518        if (count > 0) {
 519                kbuf = (char *)__get_free_page(GFP_KERNEL);
 520                if (!kbuf)
 521                        return wrote ? wrote : -ENOMEM;
 522                while (count > 0) {
 523                        unsigned long sz = size_inside_page(p, count);
 524                        unsigned long n;
 525
 526                        if (!is_vmalloc_or_module_addr((void *)p)) {
 527                                err = -ENXIO;
 528                                break;
 529                        }
 530                        n = copy_from_user(kbuf, buf, sz);
 531                        if (n) {
 532                                err = -EFAULT;
 533                                break;
 534                        }
 535                        vwrite(kbuf, (char *)p, sz);
 536                        count -= sz;
 537                        buf += sz;
 538                        virtr += sz;
 539                        p += sz;
 540                }
 541                free_page((unsigned long)kbuf);
 542        }
 543
 544        *ppos = p;
 545        return virtr + wrote ? : err;
 546}
 547#endif
 548
 549#ifdef CONFIG_DEVPORT
 550static ssize_t read_port(struct file *file, char __user *buf,
 551                         size_t count, loff_t *ppos)
 552{
 553        unsigned long i = *ppos;
 554        char __user *tmp = buf;
 555
 556        if (!access_ok(VERIFY_WRITE, buf, count))
 557                return -EFAULT;
 558        while (count-- > 0 && i < 65536) {
 559                if (__put_user(inb(i), tmp) < 0)
 560                        return -EFAULT;
 561                i++;
 562                tmp++;
 563        }
 564        *ppos = i;
 565        return tmp-buf;
 566}
 567
 568static ssize_t write_port(struct file *file, const char __user *buf,
 569                          size_t count, loff_t *ppos)
 570{
 571        unsigned long i = *ppos;
 572        const char __user *tmp = buf;
 573
 574        if (!access_ok(VERIFY_READ, buf, count))
 575                return -EFAULT;
 576        while (count-- > 0 && i < 65536) {
 577                char c;
 578                if (__get_user(c, tmp)) {
 579                        if (tmp > buf)
 580                                break;
 581                        return -EFAULT;
 582                }
 583                outb(c, i);
 584                i++;
 585                tmp++;
 586        }
 587        *ppos = i;
 588        return tmp-buf;
 589}
 590#endif
 591
 592static ssize_t read_null(struct file *file, char __user *buf,
 593                         size_t count, loff_t *ppos)
 594{
 595        return 0;
 596}
 597
 598static ssize_t write_null(struct file *file, const char __user *buf,
 599                          size_t count, loff_t *ppos)
 600{
 601        return count;
 602}
 603
 604static ssize_t aio_read_null(struct kiocb *iocb, const struct iovec *iov,
 605                             unsigned long nr_segs, loff_t pos)
 606{
 607        return 0;
 608}
 609
 610static ssize_t aio_write_null(struct kiocb *iocb, const struct iovec *iov,
 611                              unsigned long nr_segs, loff_t pos)
 612{
 613        return iov_length(iov, nr_segs);
 614}
 615
 616static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf,
 617                        struct splice_desc *sd)
 618{
 619        return sd->len;
 620}
 621
 622static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out,
 623                                 loff_t *ppos, size_t len, unsigned int flags)
 624{
 625        return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null);
 626}
 627
 628static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter)
 629{
 630        size_t written = 0;
 631
 632        while (iov_iter_count(iter)) {
 633                size_t chunk = iov_iter_count(iter), n;
 634                if (chunk > PAGE_SIZE)
 635                        chunk = PAGE_SIZE;      /* Just for latency reasons */
 636                n = iov_iter_zero(chunk, iter);
 637                if (!n && iov_iter_count(iter))
 638                        return written ? written : -EFAULT;
 639                written += n;
 640                if (signal_pending(current))
 641                        return written ? written : -ERESTARTSYS;
 642                cond_resched();
 643        }
 644        return written;
 645}
 646
 647static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 648{
 649#ifndef CONFIG_MMU
 650        return -ENOSYS;
 651#endif
 652        if (vma->vm_flags & VM_SHARED)
 653                return shmem_zero_setup(vma);
 654        return 0;
 655}
 656
 657static ssize_t write_full(struct file *file, const char __user *buf,
 658                          size_t count, loff_t *ppos)
 659{
 660        return -ENOSPC;
 661}
 662
 663/*
 664 * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
 665 * can fopen() both devices with "a" now.  This was previously impossible.
 666 * -- SRB.
 667 */
 668static loff_t null_lseek(struct file *file, loff_t offset, int orig)
 669{
 670        return file->f_pos = 0;
 671}
 672
 673/*
 674 * The memory devices use the full 32/64 bits of the offset, and so we cannot
 675 * check against negative addresses: they are ok. The return value is weird,
 676 * though, in that case (0).
 677 *
 678 * also note that seeking relative to the "end of file" isn't supported:
 679 * it has no meaning, so it returns -EINVAL.
 680 */
 681static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 682{
 683        loff_t ret;
 684
 685        mutex_lock(&file_inode(file)->i_mutex);
 686        switch (orig) {
 687        case SEEK_CUR:
 688                offset += file->f_pos;
 689        case SEEK_SET:
 690                /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
 691                if (IS_ERR_VALUE((unsigned long long)offset)) {
 692                        ret = -EOVERFLOW;
 693                        break;
 694                }
 695                file->f_pos = offset;
 696                ret = file->f_pos;
 697                force_successful_syscall_return();
 698                break;
 699        default:
 700                ret = -EINVAL;
 701        }
 702        mutex_unlock(&file_inode(file)->i_mutex);
 703        return ret;
 704}
 705
 706static int open_port(struct inode *inode, struct file *filp)
 707{
 708        return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
 709}
 710
 711#define zero_lseek      null_lseek
 712#define full_lseek      null_lseek
 713#define write_zero      write_null
 714#define aio_write_zero  aio_write_null
 715#define open_mem        open_port
 716#define open_kmem       open_mem
 717
 718static const struct file_operations mem_fops = {
 719        .llseek         = memory_lseek,
 720        .read           = read_mem,
 721        .write          = write_mem,
 722        .mmap           = mmap_mem,
 723        .open           = open_mem,
 724        .get_unmapped_area = get_unmapped_area_mem,
 725};
 726
 727#ifdef CONFIG_DEVKMEM
 728static const struct file_operations kmem_fops = {
 729        .llseek         = memory_lseek,
 730        .read           = read_kmem,
 731        .write          = write_kmem,
 732        .mmap           = mmap_kmem,
 733        .open           = open_kmem,
 734        .get_unmapped_area = get_unmapped_area_mem,
 735};
 736#endif
 737
 738static const struct file_operations null_fops = {
 739        .llseek         = null_lseek,
 740        .read           = read_null,
 741        .write          = write_null,
 742        .aio_read       = aio_read_null,
 743        .aio_write      = aio_write_null,
 744        .splice_write   = splice_write_null,
 745};
 746
 747#ifdef CONFIG_DEVPORT
 748static const struct file_operations port_fops = {
 749        .llseek         = memory_lseek,
 750        .read           = read_port,
 751        .write          = write_port,
 752        .open           = open_port,
 753};
 754#endif
 755
 756static const struct file_operations zero_fops = {
 757        .llseek         = zero_lseek,
 758        .read           = new_sync_read,
 759        .write          = write_zero,
 760        .read_iter      = read_iter_zero,
 761        .aio_write      = aio_write_zero,
 762        .mmap           = mmap_zero,
 763};
 764
 765/*
 766 * capabilities for /dev/zero
 767 * - permits private mappings, "copies" are taken of the source of zeros
 768 * - no writeback happens
 769 */
 770static struct backing_dev_info zero_bdi = {
 771        .name           = "char/mem",
 772        .capabilities   = BDI_CAP_MAP_COPY | BDI_CAP_NO_ACCT_AND_WRITEBACK,
 773};
 774
 775static const struct file_operations full_fops = {
 776        .llseek         = full_lseek,
 777        .read           = new_sync_read,
 778        .read_iter      = read_iter_zero,
 779        .write          = write_full,
 780};
 781
 782static const struct memdev {
 783        const char *name;
 784        umode_t mode;
 785        const struct file_operations *fops;
 786        struct backing_dev_info *dev_info;
 787} devlist[] = {
 788         [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
 789#ifdef CONFIG_DEVKMEM
 790         [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
 791#endif
 792         [3] = { "null", 0666, &null_fops, NULL },
 793#ifdef CONFIG_DEVPORT
 794         [4] = { "port", 0, &port_fops, NULL },
 795#endif
 796         [5] = { "zero", 0666, &zero_fops, &zero_bdi },
 797         [7] = { "full", 0666, &full_fops, NULL },
 798         [8] = { "random", 0666, &random_fops, NULL },
 799         [9] = { "urandom", 0666, &urandom_fops, NULL },
 800#ifdef CONFIG_PRINTK
 801        [11] = { "kmsg", 0644, &kmsg_fops, NULL },
 802#endif
 803};
 804
 805static int memory_open(struct inode *inode, struct file *filp)
 806{
 807        int minor;
 808        const struct memdev *dev;
 809
 810        minor = iminor(inode);
 811        if (minor >= ARRAY_SIZE(devlist))
 812                return -ENXIO;
 813
 814        dev = &devlist[minor];
 815        if (!dev->fops)
 816                return -ENXIO;
 817
 818        filp->f_op = dev->fops;
 819        if (dev->dev_info)
 820                filp->f_mapping->backing_dev_info = dev->dev_info;
 821
 822        /* Is /dev/mem or /dev/kmem ? */
 823        if (dev->dev_info == &directly_mappable_cdev_bdi)
 824                filp->f_mode |= FMODE_UNSIGNED_OFFSET;
 825
 826        if (dev->fops->open)
 827                return dev->fops->open(inode, filp);
 828
 829        return 0;
 830}
 831
 832static const struct file_operations memory_fops = {
 833        .open = memory_open,
 834        .llseek = noop_llseek,
 835};
 836
 837static char *mem_devnode(struct device *dev, umode_t *mode)
 838{
 839        if (mode && devlist[MINOR(dev->devt)].mode)
 840                *mode = devlist[MINOR(dev->devt)].mode;
 841        return NULL;
 842}
 843
 844static struct class *mem_class;
 845
 846static int __init chr_dev_init(void)
 847{
 848        int minor;
 849        int err;
 850
 851        err = bdi_init(&zero_bdi);
 852        if (err)
 853                return err;
 854
 855        if (register_chrdev(MEM_MAJOR, "mem", &memory_fops))
 856                printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 857
 858        mem_class = class_create(THIS_MODULE, "mem");
 859        if (IS_ERR(mem_class))
 860                return PTR_ERR(mem_class);
 861
 862        mem_class->devnode = mem_devnode;
 863        for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
 864                if (!devlist[minor].name)
 865                        continue;
 866
 867                /*
 868                 * Create /dev/port?
 869                 */
 870                if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
 871                        continue;
 872
 873                device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
 874                              NULL, devlist[minor].name);
 875        }
 876
 877        return tty_init();
 878}
 879
 880fs_initcall(chr_dev_init);
 881
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