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0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Provide access to virtual console memory.
0004  * /dev/vcs: the screen as it is being viewed right now (possibly scrolled)
0005  * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
0006  *            [minor: N]
0007  *
0008  * /dev/vcsaN: idem, but including attributes, and prefixed with
0009  *  the 4 bytes lines,columns,x,y (as screendump used to give).
0010  *  Attribute/character pair is in native endianity.
0011  *            [minor: N+128]
0012  *
0013  * /dev/vcsuN: similar to /dev/vcsaN but using 4-byte unicode values
0014  *  instead of 1-byte screen glyph values.
0015  *            [minor: N+64]
0016  *
0017  * /dev/vcsuaN: same idea as /dev/vcsaN for unicode (not yet implemented).
0018  *
0019  * This replaces screendump and part of selection, so that the system
0020  * administrator can control access using file system permissions.
0021  *
0022  * aeb@cwi.nl - efter Friedas begravelse - 950211
0023  *
0024  * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
0025  *   - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
0026  *   - making it shorter - scr_readw are macros which expand in PRETTY long code
0027  */
0028 
0029 #include <linux/kernel.h>
0030 #include <linux/major.h>
0031 #include <linux/errno.h>
0032 #include <linux/export.h>
0033 #include <linux/tty.h>
0034 #include <linux/interrupt.h>
0035 #include <linux/mm.h>
0036 #include <linux/init.h>
0037 #include <linux/vt_kern.h>
0038 #include <linux/selection.h>
0039 #include <linux/kbd_kern.h>
0040 #include <linux/console.h>
0041 #include <linux/device.h>
0042 #include <linux/sched.h>
0043 #include <linux/fs.h>
0044 #include <linux/poll.h>
0045 #include <linux/signal.h>
0046 #include <linux/slab.h>
0047 #include <linux/notifier.h>
0048 
0049 #include <linux/uaccess.h>
0050 #include <asm/byteorder.h>
0051 #include <asm/unaligned.h>
0052 
0053 #define HEADER_SIZE 4u
0054 #define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
0055 
0056 /*
0057  * Our minor space:
0058  *
0059  *   0 ... 63   glyph mode without attributes
0060  *  64 ... 127  unicode mode without attributes
0061  * 128 ... 191  glyph mode with attributes
0062  * 192 ... 255  unused (reserved for unicode with attributes)
0063  *
0064  * This relies on MAX_NR_CONSOLES being  <= 63, meaning 63 actual consoles
0065  * with minors 0, 64, 128 and 192 being proxies for the foreground console.
0066  */
0067 #if MAX_NR_CONSOLES > 63
0068 #warning "/dev/vcs* devices may not accommodate more than 63 consoles"
0069 #endif
0070 
0071 #define console(inode)      (iminor(inode) & 63)
0072 #define use_unicode(inode)  (iminor(inode) & 64)
0073 #define use_attributes(inode)   (iminor(inode) & 128)
0074 
0075 
0076 struct vcs_poll_data {
0077     struct notifier_block notifier;
0078     unsigned int cons_num;
0079     int event;
0080     wait_queue_head_t waitq;
0081     struct fasync_struct *fasync;
0082 };
0083 
0084 static int
0085 vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
0086 {
0087     struct vt_notifier_param *param = _param;
0088     struct vc_data *vc = param->vc;
0089     struct vcs_poll_data *poll =
0090         container_of(nb, struct vcs_poll_data, notifier);
0091     int currcons = poll->cons_num;
0092     int fa_band;
0093 
0094     switch (code) {
0095     case VT_UPDATE:
0096         fa_band = POLL_PRI;
0097         break;
0098     case VT_DEALLOCATE:
0099         fa_band = POLL_HUP;
0100         break;
0101     default:
0102         return NOTIFY_DONE;
0103     }
0104 
0105     if (currcons == 0)
0106         currcons = fg_console;
0107     else
0108         currcons--;
0109     if (currcons != vc->vc_num)
0110         return NOTIFY_DONE;
0111 
0112     poll->event = code;
0113     wake_up_interruptible(&poll->waitq);
0114     kill_fasync(&poll->fasync, SIGIO, fa_band);
0115     return NOTIFY_OK;
0116 }
0117 
0118 static void
0119 vcs_poll_data_free(struct vcs_poll_data *poll)
0120 {
0121     unregister_vt_notifier(&poll->notifier);
0122     kfree(poll);
0123 }
0124 
0125 static struct vcs_poll_data *
0126 vcs_poll_data_get(struct file *file)
0127 {
0128     struct vcs_poll_data *poll = file->private_data, *kill = NULL;
0129 
0130     if (poll)
0131         return poll;
0132 
0133     poll = kzalloc(sizeof(*poll), GFP_KERNEL);
0134     if (!poll)
0135         return NULL;
0136     poll->cons_num = console(file_inode(file));
0137     init_waitqueue_head(&poll->waitq);
0138     poll->notifier.notifier_call = vcs_notifier;
0139     /*
0140      * In order not to lose any update event, we must pretend one might
0141      * have occurred before we have a chance to register our notifier.
0142      * This is also how user space has come to detect which kernels
0143      * support POLLPRI on /dev/vcs* devices i.e. using poll() with
0144      * POLLPRI and a zero timeout.
0145      */
0146     poll->event = VT_UPDATE;
0147 
0148     if (register_vt_notifier(&poll->notifier) != 0) {
0149         kfree(poll);
0150         return NULL;
0151     }
0152 
0153     /*
0154      * This code may be called either through ->poll() or ->fasync().
0155      * If we have two threads using the same file descriptor, they could
0156      * both enter this function, both notice that the structure hasn't
0157      * been allocated yet and go ahead allocating it in parallel, but
0158      * only one of them must survive and be shared otherwise we'd leak
0159      * memory with a dangling notifier callback.
0160      */
0161     spin_lock(&file->f_lock);
0162     if (!file->private_data) {
0163         file->private_data = poll;
0164     } else {
0165         /* someone else raced ahead of us */
0166         kill = poll;
0167         poll = file->private_data;
0168     }
0169     spin_unlock(&file->f_lock);
0170     if (kill)
0171         vcs_poll_data_free(kill);
0172 
0173     return poll;
0174 }
0175 
0176 /**
0177  * vcs_vc -- return VC for @inode
0178  * @inode: inode for which to return a VC
0179  * @viewed: returns whether this console is currently foreground (viewed)
0180  *
0181  * Must be called with console_lock.
0182  */
0183 static struct vc_data *vcs_vc(struct inode *inode, bool *viewed)
0184 {
0185     unsigned int currcons = console(inode);
0186 
0187     WARN_CONSOLE_UNLOCKED();
0188 
0189     if (currcons == 0) {
0190         currcons = fg_console;
0191         if (viewed)
0192             *viewed = true;
0193     } else {
0194         currcons--;
0195         if (viewed)
0196             *viewed = false;
0197     }
0198     return vc_cons[currcons].d;
0199 }
0200 
0201 /**
0202  * vcs_size -- return size for a VC in @vc
0203  * @vc: which VC
0204  * @attr: does it use attributes?
0205  * @unicode: is it unicode?
0206  *
0207  * Must be called with console_lock.
0208  */
0209 static int vcs_size(const struct vc_data *vc, bool attr, bool unicode)
0210 {
0211     int size;
0212 
0213     WARN_CONSOLE_UNLOCKED();
0214 
0215     size = vc->vc_rows * vc->vc_cols;
0216 
0217     if (attr) {
0218         if (unicode)
0219             return -EOPNOTSUPP;
0220 
0221         size = 2 * size + HEADER_SIZE;
0222     } else if (unicode)
0223         size *= 4;
0224 
0225     return size;
0226 }
0227 
0228 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
0229 {
0230     struct inode *inode = file_inode(file);
0231     struct vc_data *vc;
0232     int size;
0233 
0234     console_lock();
0235     vc = vcs_vc(inode, NULL);
0236     if (!vc) {
0237         console_unlock();
0238         return -ENXIO;
0239     }
0240 
0241     size = vcs_size(vc, use_attributes(inode), use_unicode(inode));
0242     console_unlock();
0243     if (size < 0)
0244         return size;
0245     return fixed_size_llseek(file, offset, orig, size);
0246 }
0247 
0248 static int vcs_read_buf_uni(struct vc_data *vc, char *con_buf,
0249         unsigned int pos, unsigned int count, bool viewed)
0250 {
0251     unsigned int nr, row, col, maxcol = vc->vc_cols;
0252     int ret;
0253 
0254     ret = vc_uniscr_check(vc);
0255     if (ret)
0256         return ret;
0257 
0258     pos /= 4;
0259     row = pos / maxcol;
0260     col = pos % maxcol;
0261     nr = maxcol - col;
0262     do {
0263         if (nr > count / 4)
0264             nr = count / 4;
0265         vc_uniscr_copy_line(vc, con_buf, viewed, row, col, nr);
0266         con_buf += nr * 4;
0267         count -= nr * 4;
0268         row++;
0269         col = 0;
0270         nr = maxcol;
0271     } while (count);
0272 
0273     return 0;
0274 }
0275 
0276 static void vcs_read_buf_noattr(const struct vc_data *vc, char *con_buf,
0277         unsigned int pos, unsigned int count, bool viewed)
0278 {
0279     u16 *org;
0280     unsigned int col, maxcol = vc->vc_cols;
0281 
0282     org = screen_pos(vc, pos, viewed);
0283     col = pos % maxcol;
0284     pos += maxcol - col;
0285 
0286     while (count-- > 0) {
0287         *con_buf++ = (vcs_scr_readw(vc, org++) & 0xff);
0288         if (++col == maxcol) {
0289             org = screen_pos(vc, pos, viewed);
0290             col = 0;
0291             pos += maxcol;
0292         }
0293     }
0294 }
0295 
0296 static unsigned int vcs_read_buf(const struct vc_data *vc, char *con_buf,
0297         unsigned int pos, unsigned int count, bool viewed,
0298         unsigned int *skip)
0299 {
0300     u16 *org, *con_buf16;
0301     unsigned int col, maxcol = vc->vc_cols;
0302     unsigned int filled = count;
0303 
0304     if (pos < HEADER_SIZE) {
0305         /* clamp header values if they don't fit */
0306         con_buf[0] = min(vc->vc_rows, 0xFFu);
0307         con_buf[1] = min(vc->vc_cols, 0xFFu);
0308         getconsxy(vc, con_buf + 2);
0309 
0310         *skip += pos;
0311         count += pos;
0312         if (count > CON_BUF_SIZE) {
0313             count = CON_BUF_SIZE;
0314             filled = count - pos;
0315         }
0316 
0317         /* Advance state pointers and move on. */
0318         count -= min(HEADER_SIZE, count);
0319         pos = HEADER_SIZE;
0320         con_buf += HEADER_SIZE;
0321         /* If count >= 0, then pos is even... */
0322     } else if (pos & 1) {
0323         /*
0324          * Skip first byte for output if start address is odd. Update
0325          * region sizes up/down depending on free space in buffer.
0326          */
0327         (*skip)++;
0328         if (count < CON_BUF_SIZE)
0329             count++;
0330         else
0331             filled--;
0332     }
0333 
0334     if (!count)
0335         return filled;
0336 
0337     pos -= HEADER_SIZE;
0338     pos /= 2;
0339     col = pos % maxcol;
0340 
0341     org = screen_pos(vc, pos, viewed);
0342     pos += maxcol - col;
0343 
0344     /*
0345      * Buffer has even length, so we can always copy character + attribute.
0346      * We do not copy last byte to userspace if count is odd.
0347      */
0348     count = (count + 1) / 2;
0349     con_buf16 = (u16 *)con_buf;
0350 
0351     while (count) {
0352         *con_buf16++ = vcs_scr_readw(vc, org++);
0353         count--;
0354         if (++col == maxcol) {
0355             org = screen_pos(vc, pos, viewed);
0356             col = 0;
0357             pos += maxcol;
0358         }
0359     }
0360 
0361     return filled;
0362 }
0363 
0364 static ssize_t
0365 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
0366 {
0367     struct inode *inode = file_inode(file);
0368     struct vc_data *vc;
0369     struct vcs_poll_data *poll;
0370     unsigned int read;
0371     ssize_t ret;
0372     char *con_buf;
0373     loff_t pos;
0374     bool viewed, attr, uni_mode;
0375 
0376     con_buf = (char *) __get_free_page(GFP_KERNEL);
0377     if (!con_buf)
0378         return -ENOMEM;
0379 
0380     pos = *ppos;
0381 
0382     /* Select the proper current console and verify
0383      * sanity of the situation under the console lock.
0384      */
0385     console_lock();
0386 
0387     uni_mode = use_unicode(inode);
0388     attr = use_attributes(inode);
0389     ret = -ENXIO;
0390     vc = vcs_vc(inode, &viewed);
0391     if (!vc)
0392         goto unlock_out;
0393 
0394     ret = -EINVAL;
0395     if (pos < 0)
0396         goto unlock_out;
0397     /* we enforce 32-bit alignment for pos and count in unicode mode */
0398     if (uni_mode && (pos | count) & 3)
0399         goto unlock_out;
0400 
0401     poll = file->private_data;
0402     if (count && poll)
0403         poll->event = 0;
0404     read = 0;
0405     ret = 0;
0406     while (count) {
0407         unsigned int this_round, skip = 0;
0408         int size;
0409 
0410         /* Check whether we are above size each round,
0411          * as copy_to_user at the end of this loop
0412          * could sleep.
0413          */
0414         size = vcs_size(vc, attr, uni_mode);
0415         if (size < 0) {
0416             if (read)
0417                 break;
0418             ret = size;
0419             goto unlock_out;
0420         }
0421         if (pos >= size)
0422             break;
0423         if (count > size - pos)
0424             count = size - pos;
0425 
0426         this_round = count;
0427         if (this_round > CON_BUF_SIZE)
0428             this_round = CON_BUF_SIZE;
0429 
0430         /* Perform the whole read into the local con_buf.
0431          * Then we can drop the console spinlock and safely
0432          * attempt to move it to userspace.
0433          */
0434 
0435         if (uni_mode) {
0436             ret = vcs_read_buf_uni(vc, con_buf, pos, this_round,
0437                     viewed);
0438             if (ret)
0439                 break;
0440         } else if (!attr) {
0441             vcs_read_buf_noattr(vc, con_buf, pos, this_round,
0442                     viewed);
0443         } else {
0444             this_round = vcs_read_buf(vc, con_buf, pos, this_round,
0445                     viewed, &skip);
0446         }
0447 
0448         /* Finally, release the console semaphore while we push
0449          * all the data to userspace from our temporary buffer.
0450          *
0451          * AKPM: Even though it's a semaphore, we should drop it because
0452          * the pagefault handling code may want to call printk().
0453          */
0454 
0455         console_unlock();
0456         ret = copy_to_user(buf, con_buf + skip, this_round);
0457         console_lock();
0458 
0459         if (ret) {
0460             read += this_round - ret;
0461             ret = -EFAULT;
0462             break;
0463         }
0464         buf += this_round;
0465         pos += this_round;
0466         read += this_round;
0467         count -= this_round;
0468     }
0469     *ppos += read;
0470     if (read)
0471         ret = read;
0472 unlock_out:
0473     console_unlock();
0474     free_page((unsigned long) con_buf);
0475     return ret;
0476 }
0477 
0478 static u16 *vcs_write_buf_noattr(struct vc_data *vc, const char *con_buf,
0479         unsigned int pos, unsigned int count, bool viewed, u16 **org0)
0480 {
0481     u16 *org;
0482     unsigned int col, maxcol = vc->vc_cols;
0483 
0484     *org0 = org = screen_pos(vc, pos, viewed);
0485     col = pos % maxcol;
0486     pos += maxcol - col;
0487 
0488     while (count > 0) {
0489         unsigned char c = *con_buf++;
0490 
0491         count--;
0492         vcs_scr_writew(vc,
0493                    (vcs_scr_readw(vc, org) & 0xff00) | c, org);
0494         org++;
0495         if (++col == maxcol) {
0496             org = screen_pos(vc, pos, viewed);
0497             col = 0;
0498             pos += maxcol;
0499         }
0500     }
0501 
0502     return org;
0503 }
0504 
0505 /*
0506  * Compilers (gcc 10) are unable to optimize the swap in cpu_to_le16. So do it
0507  * the poor man way.
0508  */
0509 static inline u16 vc_compile_le16(u8 hi, u8 lo)
0510 {
0511 #ifdef __BIG_ENDIAN
0512     return (lo << 8u) | hi;
0513 #else
0514     return (hi << 8u) | lo;
0515 #endif
0516 }
0517 
0518 static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf,
0519         unsigned int pos, unsigned int count, bool viewed, u16 **org0)
0520 {
0521     u16 *org;
0522     unsigned int col, maxcol = vc->vc_cols;
0523     unsigned char c;
0524 
0525     /* header */
0526     if (pos < HEADER_SIZE) {
0527         char header[HEADER_SIZE];
0528 
0529         getconsxy(vc, header + 2);
0530         while (pos < HEADER_SIZE && count > 0) {
0531             count--;
0532             header[pos++] = *con_buf++;
0533         }
0534         if (!viewed)
0535             putconsxy(vc, header + 2);
0536     }
0537 
0538     if (!count)
0539         return NULL;
0540 
0541     pos -= HEADER_SIZE;
0542     col = (pos/2) % maxcol;
0543 
0544     *org0 = org = screen_pos(vc, pos/2, viewed);
0545 
0546     /* odd pos -- the first single character */
0547     if (pos & 1) {
0548         count--;
0549         c = *con_buf++;
0550         vcs_scr_writew(vc, vc_compile_le16(c, vcs_scr_readw(vc, org)),
0551                 org);
0552         org++;
0553         pos++;
0554         if (++col == maxcol) {
0555             org = screen_pos(vc, pos/2, viewed);
0556             col = 0;
0557         }
0558     }
0559 
0560     pos /= 2;
0561     pos += maxcol - col;
0562 
0563     /* even pos -- handle attr+character pairs */
0564     while (count > 1) {
0565         unsigned short w;
0566 
0567         w = get_unaligned(((unsigned short *)con_buf));
0568         vcs_scr_writew(vc, w, org++);
0569         con_buf += 2;
0570         count -= 2;
0571         if (++col == maxcol) {
0572             org = screen_pos(vc, pos, viewed);
0573             col = 0;
0574             pos += maxcol;
0575         }
0576     }
0577 
0578     if (!count)
0579         return org;
0580 
0581     /* odd pos -- the remaining character */
0582     c = *con_buf++;
0583     vcs_scr_writew(vc, vc_compile_le16(vcs_scr_readw(vc, org) >> 8, c),
0584                 org);
0585 
0586     return org;
0587 }
0588 
0589 static ssize_t
0590 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
0591 {
0592     struct inode *inode = file_inode(file);
0593     struct vc_data *vc;
0594     char *con_buf;
0595     u16 *org0, *org;
0596     unsigned int written;
0597     int size;
0598     ssize_t ret;
0599     loff_t pos;
0600     bool viewed, attr;
0601 
0602     if (use_unicode(inode))
0603         return -EOPNOTSUPP;
0604 
0605     con_buf = (char *) __get_free_page(GFP_KERNEL);
0606     if (!con_buf)
0607         return -ENOMEM;
0608 
0609     pos = *ppos;
0610 
0611     /* Select the proper current console and verify
0612      * sanity of the situation under the console lock.
0613      */
0614     console_lock();
0615 
0616     attr = use_attributes(inode);
0617     ret = -ENXIO;
0618     vc = vcs_vc(inode, &viewed);
0619     if (!vc)
0620         goto unlock_out;
0621 
0622     size = vcs_size(vc, attr, false);
0623     if (size < 0) {
0624         ret = size;
0625         goto unlock_out;
0626     }
0627     ret = -EINVAL;
0628     if (pos < 0 || pos > size)
0629         goto unlock_out;
0630     if (count > size - pos)
0631         count = size - pos;
0632     written = 0;
0633     while (count) {
0634         unsigned int this_round = count;
0635 
0636         if (this_round > CON_BUF_SIZE)
0637             this_round = CON_BUF_SIZE;
0638 
0639         /* Temporarily drop the console lock so that we can read
0640          * in the write data from userspace safely.
0641          */
0642         console_unlock();
0643         ret = copy_from_user(con_buf, buf, this_round);
0644         console_lock();
0645 
0646         if (ret) {
0647             this_round -= ret;
0648             if (!this_round) {
0649                 /* Abort loop if no data were copied. Otherwise
0650                  * fail with -EFAULT.
0651                  */
0652                 if (written)
0653                     break;
0654                 ret = -EFAULT;
0655                 goto unlock_out;
0656             }
0657         }
0658 
0659         /* The vcs_size might have changed while we slept to grab
0660          * the user buffer, so recheck.
0661          * Return data written up to now on failure.
0662          */
0663         size = vcs_size(vc, attr, false);
0664         if (size < 0) {
0665             if (written)
0666                 break;
0667             ret = size;
0668             goto unlock_out;
0669         }
0670         if (pos >= size)
0671             break;
0672         if (this_round > size - pos)
0673             this_round = size - pos;
0674 
0675         /* OK, now actually push the write to the console
0676          * under the lock using the local kernel buffer.
0677          */
0678 
0679         if (attr)
0680             org = vcs_write_buf(vc, con_buf, pos, this_round,
0681                     viewed, &org0);
0682         else
0683             org = vcs_write_buf_noattr(vc, con_buf, pos, this_round,
0684                     viewed, &org0);
0685 
0686         count -= this_round;
0687         written += this_round;
0688         buf += this_round;
0689         pos += this_round;
0690         if (org)
0691             update_region(vc, (unsigned long)(org0), org - org0);
0692     }
0693     *ppos += written;
0694     ret = written;
0695     if (written)
0696         vcs_scr_updated(vc);
0697 
0698 unlock_out:
0699     console_unlock();
0700     free_page((unsigned long) con_buf);
0701     return ret;
0702 }
0703 
0704 static __poll_t
0705 vcs_poll(struct file *file, poll_table *wait)
0706 {
0707     struct vcs_poll_data *poll = vcs_poll_data_get(file);
0708     __poll_t ret = DEFAULT_POLLMASK|EPOLLERR;
0709 
0710     if (poll) {
0711         poll_wait(file, &poll->waitq, wait);
0712         switch (poll->event) {
0713         case VT_UPDATE:
0714             ret = DEFAULT_POLLMASK|EPOLLPRI;
0715             break;
0716         case VT_DEALLOCATE:
0717             ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR;
0718             break;
0719         case 0:
0720             ret = DEFAULT_POLLMASK;
0721             break;
0722         }
0723     }
0724     return ret;
0725 }
0726 
0727 static int
0728 vcs_fasync(int fd, struct file *file, int on)
0729 {
0730     struct vcs_poll_data *poll = file->private_data;
0731 
0732     if (!poll) {
0733         /* don't allocate anything if all we want is disable fasync */
0734         if (!on)
0735             return 0;
0736         poll = vcs_poll_data_get(file);
0737         if (!poll)
0738             return -ENOMEM;
0739     }
0740 
0741     return fasync_helper(fd, file, on, &poll->fasync);
0742 }
0743 
0744 static int
0745 vcs_open(struct inode *inode, struct file *filp)
0746 {
0747     unsigned int currcons = console(inode);
0748     bool attr = use_attributes(inode);
0749     bool uni_mode = use_unicode(inode);
0750     int ret = 0;
0751 
0752     /* we currently don't support attributes in unicode mode */
0753     if (attr && uni_mode)
0754         return -EOPNOTSUPP;
0755 
0756     console_lock();
0757     if(currcons && !vc_cons_allocated(currcons-1))
0758         ret = -ENXIO;
0759     console_unlock();
0760     return ret;
0761 }
0762 
0763 static int vcs_release(struct inode *inode, struct file *file)
0764 {
0765     struct vcs_poll_data *poll = file->private_data;
0766 
0767     if (poll)
0768         vcs_poll_data_free(poll);
0769     return 0;
0770 }
0771 
0772 static const struct file_operations vcs_fops = {
0773     .llseek     = vcs_lseek,
0774     .read       = vcs_read,
0775     .write      = vcs_write,
0776     .poll       = vcs_poll,
0777     .fasync     = vcs_fasync,
0778     .open       = vcs_open,
0779     .release    = vcs_release,
0780 };
0781 
0782 static struct class *vc_class;
0783 
0784 void vcs_make_sysfs(int index)
0785 {
0786     device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
0787               "vcs%u", index + 1);
0788     device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
0789               "vcsu%u", index + 1);
0790     device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
0791               "vcsa%u", index + 1);
0792 }
0793 
0794 void vcs_remove_sysfs(int index)
0795 {
0796     device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
0797     device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
0798     device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
0799 }
0800 
0801 int __init vcs_init(void)
0802 {
0803     unsigned int i;
0804 
0805     if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
0806         panic("unable to get major %d for vcs device", VCS_MAJOR);
0807     vc_class = class_create(THIS_MODULE, "vc");
0808 
0809     device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
0810     device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
0811     device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
0812     for (i = 0; i < MIN_NR_CONSOLES; i++)
0813         vcs_make_sysfs(i);
0814     return 0;
0815 }
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