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-rw-r--r--drivers/tty/vt/vc_screen.c719
1 files changed, 719 insertions, 0 deletions
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
new file mode 100644
index 000000000..2fb509d57
--- /dev/null
+++ b/drivers/tty/vt/vc_screen.c
@@ -0,0 +1,719 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Provide access to virtual console memory.
+ * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
+ * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
+ * [minor: N]
+ *
+ * /dev/vcsaN: idem, but including attributes, and prefixed with
+ * the 4 bytes lines,columns,x,y (as screendump used to give).
+ * Attribute/character pair is in native endianity.
+ * [minor: N+128]
+ *
+ * /dev/vcsuN: similar to /dev/vcsaN but using 4-byte unicode values
+ * instead of 1-byte screen glyph values.
+ * [minor: N+64]
+ *
+ * /dev/vcsuaN: same idea as /dev/vcsaN for unicode (not yet implemented).
+ *
+ * This replaces screendump and part of selection, so that the system
+ * administrator can control access using file system permissions.
+ *
+ * aeb@cwi.nl - efter Friedas begravelse - 950211
+ *
+ * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
+ * - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
+ * - making it shorter - scr_readw are macros which expand in PRETTY long code
+ */
+
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/tty.h>
+#include <linux/interrupt.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/vt_kern.h>
+#include <linux/selection.h>
+#include <linux/kbd_kern.h>
+#include <linux/console.h>
+#include <linux/device.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/notifier.h>
+
+#include <linux/uaccess.h>
+#include <asm/byteorder.h>
+#include <asm/unaligned.h>
+
+#undef attr
+#undef org
+#undef addr
+#define HEADER_SIZE 4
+
+#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
+
+/*
+ * Our minor space:
+ *
+ * 0 ... 63 glyph mode without attributes
+ * 64 ... 127 unicode mode without attributes
+ * 128 ... 191 glyph mode with attributes
+ * 192 ... 255 unused (reserved for unicode with attributes)
+ *
+ * This relies on MAX_NR_CONSOLES being <= 63, meaning 63 actual consoles
+ * with minors 0, 64, 128 and 192 being proxies for the foreground console.
+ */
+#if MAX_NR_CONSOLES > 63
+#warning "/dev/vcs* devices may not accommodate more than 63 consoles"
+#endif
+
+#define console(inode) (iminor(inode) & 63)
+#define use_unicode(inode) (iminor(inode) & 64)
+#define use_attributes(inode) (iminor(inode) & 128)
+
+
+struct vcs_poll_data {
+ struct notifier_block notifier;
+ unsigned int cons_num;
+ bool seen_last_update;
+ wait_queue_head_t waitq;
+ struct fasync_struct *fasync;
+};
+
+static int
+vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
+{
+ struct vt_notifier_param *param = _param;
+ struct vc_data *vc = param->vc;
+ struct vcs_poll_data *poll =
+ container_of(nb, struct vcs_poll_data, notifier);
+ int currcons = poll->cons_num;
+
+ if (code != VT_UPDATE)
+ return NOTIFY_DONE;
+
+ if (currcons == 0)
+ currcons = fg_console;
+ else
+ currcons--;
+ if (currcons != vc->vc_num)
+ return NOTIFY_DONE;
+
+ poll->seen_last_update = false;
+ wake_up_interruptible(&poll->waitq);
+ kill_fasync(&poll->fasync, SIGIO, POLL_IN);
+ return NOTIFY_OK;
+}
+
+static void
+vcs_poll_data_free(struct vcs_poll_data *poll)
+{
+ unregister_vt_notifier(&poll->notifier);
+ kfree(poll);
+}
+
+static struct vcs_poll_data *
+vcs_poll_data_get(struct file *file)
+{
+ struct vcs_poll_data *poll = file->private_data, *kill = NULL;
+
+ if (poll)
+ return poll;
+
+ poll = kzalloc(sizeof(*poll), GFP_KERNEL);
+ if (!poll)
+ return NULL;
+ poll->cons_num = console(file_inode(file));
+ init_waitqueue_head(&poll->waitq);
+ poll->notifier.notifier_call = vcs_notifier;
+ if (register_vt_notifier(&poll->notifier) != 0) {
+ kfree(poll);
+ return NULL;
+ }
+
+ /*
+ * This code may be called either through ->poll() or ->fasync().
+ * If we have two threads using the same file descriptor, they could
+ * both enter this function, both notice that the structure hasn't
+ * been allocated yet and go ahead allocating it in parallel, but
+ * only one of them must survive and be shared otherwise we'd leak
+ * memory with a dangling notifier callback.
+ */
+ spin_lock(&file->f_lock);
+ if (!file->private_data) {
+ file->private_data = poll;
+ } else {
+ /* someone else raced ahead of us */
+ kill = poll;
+ poll = file->private_data;
+ }
+ spin_unlock(&file->f_lock);
+ if (kill)
+ vcs_poll_data_free(kill);
+
+ return poll;
+}
+
+/*
+ * Returns VC for inode.
+ * Must be called with console_lock.
+ */
+static struct vc_data*
+vcs_vc(struct inode *inode, int *viewed)
+{
+ unsigned int currcons = console(inode);
+
+ WARN_CONSOLE_UNLOCKED();
+
+ if (currcons == 0) {
+ currcons = fg_console;
+ if (viewed)
+ *viewed = 1;
+ } else {
+ currcons--;
+ if (viewed)
+ *viewed = 0;
+ }
+ return vc_cons[currcons].d;
+}
+
+/*
+ * Returns size for VC carried by inode.
+ * Must be called with console_lock.
+ */
+static int
+vcs_size(struct inode *inode)
+{
+ int size;
+ struct vc_data *vc;
+
+ WARN_CONSOLE_UNLOCKED();
+
+ vc = vcs_vc(inode, NULL);
+ if (!vc)
+ return -ENXIO;
+
+ size = vc->vc_rows * vc->vc_cols;
+
+ if (use_attributes(inode)) {
+ if (use_unicode(inode))
+ return -EOPNOTSUPP;
+ size = 2*size + HEADER_SIZE;
+ } else if (use_unicode(inode))
+ size *= 4;
+ return size;
+}
+
+static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
+{
+ int size;
+
+ console_lock();
+ size = vcs_size(file_inode(file));
+ console_unlock();
+ if (size < 0)
+ return size;
+ return fixed_size_llseek(file, offset, orig, size);
+}
+
+
+static ssize_t
+vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+ struct inode *inode = file_inode(file);
+ struct vc_data *vc;
+ struct vcs_poll_data *poll;
+ long pos, read;
+ int attr, uni_mode, row, col, maxcol, viewed;
+ unsigned short *org = NULL;
+ ssize_t ret;
+ char *con_buf;
+
+ con_buf = (char *) __get_free_page(GFP_KERNEL);
+ if (!con_buf)
+ return -ENOMEM;
+
+ pos = *ppos;
+
+ /* Select the proper current console and verify
+ * sanity of the situation under the console lock.
+ */
+ console_lock();
+
+ uni_mode = use_unicode(inode);
+ attr = use_attributes(inode);
+ ret = -ENXIO;
+ vc = vcs_vc(inode, &viewed);
+ if (!vc)
+ goto unlock_out;
+
+ ret = -EINVAL;
+ if (pos < 0)
+ goto unlock_out;
+ /* we enforce 32-bit alignment for pos and count in unicode mode */
+ if (uni_mode && (pos | count) & 3)
+ goto unlock_out;
+
+ poll = file->private_data;
+ if (count && poll)
+ poll->seen_last_update = true;
+ read = 0;
+ ret = 0;
+ while (count) {
+ char *con_buf0, *con_buf_start;
+ long this_round, size;
+ ssize_t orig_count;
+ long p = pos;
+
+ /* Check whether we are above size each round,
+ * as copy_to_user at the end of this loop
+ * could sleep.
+ */
+ size = vcs_size(inode);
+ if (size < 0) {
+ if (read)
+ break;
+ ret = size;
+ goto unlock_out;
+ }
+ if (pos >= size)
+ break;
+ if (count > size - pos)
+ count = size - pos;
+
+ this_round = count;
+ if (this_round > CON_BUF_SIZE)
+ this_round = CON_BUF_SIZE;
+
+ /* Perform the whole read into the local con_buf.
+ * Then we can drop the console spinlock and safely
+ * attempt to move it to userspace.
+ */
+
+ con_buf_start = con_buf0 = con_buf;
+ orig_count = this_round;
+ maxcol = vc->vc_cols;
+ if (uni_mode) {
+ unsigned int nr;
+
+ ret = vc_uniscr_check(vc);
+ if (ret)
+ break;
+ p /= 4;
+ row = p / vc->vc_cols;
+ col = p % maxcol;
+ nr = maxcol - col;
+ do {
+ if (nr > this_round/4)
+ nr = this_round/4;
+ vc_uniscr_copy_line(vc, con_buf0, viewed,
+ row, col, nr);
+ con_buf0 += nr * 4;
+ this_round -= nr * 4;
+ row++;
+ col = 0;
+ nr = maxcol;
+ } while (this_round);
+ } else if (!attr) {
+ org = screen_pos(vc, p, viewed);
+ col = p % maxcol;
+ p += maxcol - col;
+ while (this_round-- > 0) {
+ *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
+ if (++col == maxcol) {
+ org = screen_pos(vc, p, viewed);
+ col = 0;
+ p += maxcol;
+ }
+ }
+ } else {
+ if (p < HEADER_SIZE) {
+ size_t tmp_count;
+
+ con_buf0[0] = (char)vc->vc_rows;
+ con_buf0[1] = (char)vc->vc_cols;
+ getconsxy(vc, con_buf0 + 2);
+
+ con_buf_start += p;
+ this_round += p;
+ if (this_round > CON_BUF_SIZE) {
+ this_round = CON_BUF_SIZE;
+ orig_count = this_round - p;
+ }
+
+ tmp_count = HEADER_SIZE;
+ if (tmp_count > this_round)
+ tmp_count = this_round;
+
+ /* Advance state pointers and move on. */
+ this_round -= tmp_count;
+ p = HEADER_SIZE;
+ con_buf0 = con_buf + HEADER_SIZE;
+ /* If this_round >= 0, then p is even... */
+ } else if (p & 1) {
+ /* Skip first byte for output if start address is odd
+ * Update region sizes up/down depending on free
+ * space in buffer.
+ */
+ con_buf_start++;
+ if (this_round < CON_BUF_SIZE)
+ this_round++;
+ else
+ orig_count--;
+ }
+ if (this_round > 0) {
+ unsigned short *tmp_buf = (unsigned short *)con_buf0;
+
+ p -= HEADER_SIZE;
+ p /= 2;
+ col = p % maxcol;
+
+ org = screen_pos(vc, p, viewed);
+ p += maxcol - col;
+
+ /* Buffer has even length, so we can always copy
+ * character + attribute. We do not copy last byte
+ * to userspace if this_round is odd.
+ */
+ this_round = (this_round + 1) >> 1;
+
+ while (this_round) {
+ *tmp_buf++ = vcs_scr_readw(vc, org++);
+ this_round --;
+ if (++col == maxcol) {
+ org = screen_pos(vc, p, viewed);
+ col = 0;
+ p += maxcol;
+ }
+ }
+ }
+ }
+
+ /* Finally, release the console semaphore while we push
+ * all the data to userspace from our temporary buffer.
+ *
+ * AKPM: Even though it's a semaphore, we should drop it because
+ * the pagefault handling code may want to call printk().
+ */
+
+ console_unlock();
+ ret = copy_to_user(buf, con_buf_start, orig_count);
+ console_lock();
+
+ if (ret) {
+ read += (orig_count - ret);
+ ret = -EFAULT;
+ break;
+ }
+ buf += orig_count;
+ pos += orig_count;
+ read += orig_count;
+ count -= orig_count;
+ }
+ *ppos += read;
+ if (read)
+ ret = read;
+unlock_out:
+ console_unlock();
+ free_page((unsigned long) con_buf);
+ return ret;
+}
+
+static ssize_t
+vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+ struct inode *inode = file_inode(file);
+ struct vc_data *vc;
+ long pos;
+ long attr, size, written;
+ char *con_buf0;
+ int col, maxcol, viewed;
+ u16 *org0 = NULL, *org = NULL;
+ size_t ret;
+ char *con_buf;
+
+ if (use_unicode(inode))
+ return -EOPNOTSUPP;
+
+ con_buf = (char *) __get_free_page(GFP_KERNEL);
+ if (!con_buf)
+ return -ENOMEM;
+
+ pos = *ppos;
+
+ /* Select the proper current console and verify
+ * sanity of the situation under the console lock.
+ */
+ console_lock();
+
+ attr = use_attributes(inode);
+ ret = -ENXIO;
+ vc = vcs_vc(inode, &viewed);
+ if (!vc)
+ goto unlock_out;
+
+ size = vcs_size(inode);
+ ret = -EINVAL;
+ if (pos < 0 || pos > size)
+ goto unlock_out;
+ if (count > size - pos)
+ count = size - pos;
+ written = 0;
+ while (count) {
+ long this_round = count;
+ size_t orig_count;
+ long p;
+
+ if (this_round > CON_BUF_SIZE)
+ this_round = CON_BUF_SIZE;
+
+ /* Temporarily drop the console lock so that we can read
+ * in the write data from userspace safely.
+ */
+ console_unlock();
+ ret = copy_from_user(con_buf, buf, this_round);
+ console_lock();
+
+ if (ret) {
+ this_round -= ret;
+ if (!this_round) {
+ /* Abort loop if no data were copied. Otherwise
+ * fail with -EFAULT.
+ */
+ if (written)
+ break;
+ ret = -EFAULT;
+ goto unlock_out;
+ }
+ }
+
+ /* The vcs_size might have changed while we slept to grab
+ * the user buffer, so recheck.
+ * Return data written up to now on failure.
+ */
+ size = vcs_size(inode);
+ if (size < 0) {
+ if (written)
+ break;
+ ret = size;
+ goto unlock_out;
+ }
+ if (pos >= size)
+ break;
+ if (this_round > size - pos)
+ this_round = size - pos;
+
+ /* OK, now actually push the write to the console
+ * under the lock using the local kernel buffer.
+ */
+
+ con_buf0 = con_buf;
+ orig_count = this_round;
+ maxcol = vc->vc_cols;
+ p = pos;
+ if (!attr) {
+ org0 = org = screen_pos(vc, p, viewed);
+ col = p % maxcol;
+ p += maxcol - col;
+
+ while (this_round > 0) {
+ unsigned char c = *con_buf0++;
+
+ this_round--;
+ vcs_scr_writew(vc,
+ (vcs_scr_readw(vc, org) & 0xff00) | c, org);
+ org++;
+ if (++col == maxcol) {
+ org = screen_pos(vc, p, viewed);
+ col = 0;
+ p += maxcol;
+ }
+ }
+ } else {
+ if (p < HEADER_SIZE) {
+ char header[HEADER_SIZE];
+
+ getconsxy(vc, header + 2);
+ while (p < HEADER_SIZE && this_round > 0) {
+ this_round--;
+ header[p++] = *con_buf0++;
+ }
+ if (!viewed)
+ putconsxy(vc, header + 2);
+ }
+ p -= HEADER_SIZE;
+ col = (p/2) % maxcol;
+ if (this_round > 0) {
+ org0 = org = screen_pos(vc, p/2, viewed);
+ if ((p & 1) && this_round > 0) {
+ char c;
+
+ this_round--;
+ c = *con_buf0++;
+#ifdef __BIG_ENDIAN
+ vcs_scr_writew(vc, c |
+ (vcs_scr_readw(vc, org) & 0xff00), org);
+#else
+ vcs_scr_writew(vc, (c << 8) |
+ (vcs_scr_readw(vc, org) & 0xff), org);
+#endif
+ org++;
+ p++;
+ if (++col == maxcol) {
+ org = screen_pos(vc, p/2, viewed);
+ col = 0;
+ }
+ }
+ p /= 2;
+ p += maxcol - col;
+ }
+ while (this_round > 1) {
+ unsigned short w;
+
+ w = get_unaligned(((unsigned short *)con_buf0));
+ vcs_scr_writew(vc, w, org++);
+ con_buf0 += 2;
+ this_round -= 2;
+ if (++col == maxcol) {
+ org = screen_pos(vc, p, viewed);
+ col = 0;
+ p += maxcol;
+ }
+ }
+ if (this_round > 0) {
+ unsigned char c;
+
+ c = *con_buf0++;
+#ifdef __BIG_ENDIAN
+ vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
+#else
+ vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
+#endif
+ }
+ }
+ count -= orig_count;
+ written += orig_count;
+ buf += orig_count;
+ pos += orig_count;
+ if (org0)
+ update_region(vc, (unsigned long)(org0), org - org0);
+ }
+ *ppos += written;
+ ret = written;
+ if (written)
+ vcs_scr_updated(vc);
+
+unlock_out:
+ console_unlock();
+ free_page((unsigned long) con_buf);
+ return ret;
+}
+
+static __poll_t
+vcs_poll(struct file *file, poll_table *wait)
+{
+ struct vcs_poll_data *poll = vcs_poll_data_get(file);
+ __poll_t ret = DEFAULT_POLLMASK|EPOLLERR|EPOLLPRI;
+
+ if (poll) {
+ poll_wait(file, &poll->waitq, wait);
+ if (poll->seen_last_update)
+ ret = DEFAULT_POLLMASK;
+ }
+ return ret;
+}
+
+static int
+vcs_fasync(int fd, struct file *file, int on)
+{
+ struct vcs_poll_data *poll = file->private_data;
+
+ if (!poll) {
+ /* don't allocate anything if all we want is disable fasync */
+ if (!on)
+ return 0;
+ poll = vcs_poll_data_get(file);
+ if (!poll)
+ return -ENOMEM;
+ }
+
+ return fasync_helper(fd, file, on, &poll->fasync);
+}
+
+static int
+vcs_open(struct inode *inode, struct file *filp)
+{
+ unsigned int currcons = console(inode);
+ bool attr = use_attributes(inode);
+ bool uni_mode = use_unicode(inode);
+ int ret = 0;
+
+ /* we currently don't support attributes in unicode mode */
+ if (attr && uni_mode)
+ return -EOPNOTSUPP;
+
+ console_lock();
+ if(currcons && !vc_cons_allocated(currcons-1))
+ ret = -ENXIO;
+ console_unlock();
+ return ret;
+}
+
+static int vcs_release(struct inode *inode, struct file *file)
+{
+ struct vcs_poll_data *poll = file->private_data;
+
+ if (poll)
+ vcs_poll_data_free(poll);
+ return 0;
+}
+
+static const struct file_operations vcs_fops = {
+ .llseek = vcs_lseek,
+ .read = vcs_read,
+ .write = vcs_write,
+ .poll = vcs_poll,
+ .fasync = vcs_fasync,
+ .open = vcs_open,
+ .release = vcs_release,
+};
+
+static struct class *vc_class;
+
+void vcs_make_sysfs(int index)
+{
+ device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
+ "vcs%u", index + 1);
+ device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
+ "vcsu%u", index + 1);
+ device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
+ "vcsa%u", index + 1);
+}
+
+void vcs_remove_sysfs(int index)
+{
+ device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
+ device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
+ device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
+}
+
+int __init vcs_init(void)
+{
+ unsigned int i;
+
+ if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
+ panic("unable to get major %d for vcs device", VCS_MAJOR);
+ vc_class = class_create(THIS_MODULE, "vc");
+
+ device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
+ device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
+ device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
+ for (i = 0; i < MIN_NR_CONSOLES; i++)
+ vcs_make_sysfs(i);
+ return 0;
+}
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