From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 11 Apr 2024 10:27:49 +0200 Subject: Adding upstream version 6.6.15. Signed-off-by: Daniel Baumann --- drivers/tty/vt/vc_screen.c | 822 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 822 insertions(+) create mode 100644 drivers/tty/vt/vc_screen.c (limited to 'drivers/tty/vt/vc_screen.c') diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c new file mode 100644 index 0000000000..829c4be66f --- /dev/null +++ b/drivers/tty/vt/vc_screen.c @@ -0,0 +1,822 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Provide access to virtual console memory. + * /dev/vcs: 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +#define HEADER_SIZE 4u +#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; + int event; + 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; + int fa_band; + + switch (code) { + case VT_UPDATE: + fa_band = POLL_PRI; + break; + case VT_DEALLOCATE: + fa_band = POLL_HUP; + break; + default: + return NOTIFY_DONE; + } + + if (currcons == 0) + currcons = fg_console; + else + currcons--; + if (currcons != vc->vc_num) + return NOTIFY_DONE; + + poll->event = code; + wake_up_interruptible(&poll->waitq); + kill_fasync(&poll->fasync, SIGIO, fa_band); + 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; + /* + * In order not to lose any update event, we must pretend one might + * have occurred before we have a chance to register our notifier. + * This is also how user space has come to detect which kernels + * support POLLPRI on /dev/vcs* devices i.e. using poll() with + * POLLPRI and a zero timeout. + */ + poll->event = VT_UPDATE; + + 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; +} + +/** + * vcs_vc -- return VC for @inode + * @inode: inode for which to return a VC + * @viewed: returns whether this console is currently foreground (viewed) + * + * Must be called with console_lock. + */ +static struct vc_data *vcs_vc(struct inode *inode, bool *viewed) +{ + unsigned int currcons = console(inode); + + WARN_CONSOLE_UNLOCKED(); + + if (currcons == 0) { + currcons = fg_console; + if (viewed) + *viewed = true; + } else { + currcons--; + if (viewed) + *viewed = false; + } + return vc_cons[currcons].d; +} + +/** + * vcs_size -- return size for a VC in @vc + * @vc: which VC + * @attr: does it use attributes? + * @unicode: is it unicode? + * + * Must be called with console_lock. + */ +static int vcs_size(const struct vc_data *vc, bool attr, bool unicode) +{ + int size; + + WARN_CONSOLE_UNLOCKED(); + + size = vc->vc_rows * vc->vc_cols; + + if (attr) { + if (unicode) + return -EOPNOTSUPP; + + size = 2 * size + HEADER_SIZE; + } else if (unicode) + size *= 4; + + return size; +} + +static loff_t vcs_lseek(struct file *file, loff_t offset, int orig) +{ + struct inode *inode = file_inode(file); + struct vc_data *vc; + int size; + + console_lock(); + vc = vcs_vc(inode, NULL); + if (!vc) { + console_unlock(); + return -ENXIO; + } + + size = vcs_size(vc, use_attributes(inode), use_unicode(inode)); + console_unlock(); + if (size < 0) + return size; + return fixed_size_llseek(file, offset, orig, size); +} + +static int vcs_read_buf_uni(struct vc_data *vc, char *con_buf, + unsigned int pos, unsigned int count, bool viewed) +{ + unsigned int nr, row, col, maxcol = vc->vc_cols; + int ret; + + ret = vc_uniscr_check(vc); + if (ret) + return ret; + + pos /= 4; + row = pos / maxcol; + col = pos % maxcol; + nr = maxcol - col; + do { + if (nr > count / 4) + nr = count / 4; + vc_uniscr_copy_line(vc, con_buf, viewed, row, col, nr); + con_buf += nr * 4; + count -= nr * 4; + row++; + col = 0; + nr = maxcol; + } while (count); + + return 0; +} + +static void vcs_read_buf_noattr(const struct vc_data *vc, char *con_buf, + unsigned int pos, unsigned int count, bool viewed) +{ + u16 *org; + unsigned int col, maxcol = vc->vc_cols; + + org = screen_pos(vc, pos, viewed); + col = pos % maxcol; + pos += maxcol - col; + + while (count-- > 0) { + *con_buf++ = (vcs_scr_readw(vc, org++) & 0xff); + if (++col == maxcol) { + org = screen_pos(vc, pos, viewed); + col = 0; + pos += maxcol; + } + } +} + +static unsigned int vcs_read_buf(const struct vc_data *vc, char *con_buf, + unsigned int pos, unsigned int count, bool viewed, + unsigned int *skip) +{ + u16 *org, *con_buf16; + unsigned int col, maxcol = vc->vc_cols; + unsigned int filled = count; + + if (pos < HEADER_SIZE) { + /* clamp header values if they don't fit */ + con_buf[0] = min(vc->vc_rows, 0xFFu); + con_buf[1] = min(vc->vc_cols, 0xFFu); + getconsxy(vc, con_buf + 2); + + *skip += pos; + count += pos; + if (count > CON_BUF_SIZE) { + count = CON_BUF_SIZE; + filled = count - pos; + } + + /* Advance state pointers and move on. */ + count -= min(HEADER_SIZE, count); + pos = HEADER_SIZE; + con_buf += HEADER_SIZE; + /* If count >= 0, then pos is even... */ + } else if (pos & 1) { + /* + * Skip first byte for output if start address is odd. Update + * region sizes up/down depending on free space in buffer. + */ + (*skip)++; + if (count < CON_BUF_SIZE) + count++; + else + filled--; + } + + if (!count) + return filled; + + pos -= HEADER_SIZE; + pos /= 2; + col = pos % maxcol; + + org = screen_pos(vc, pos, viewed); + pos += maxcol - col; + + /* + * Buffer has even length, so we can always copy character + attribute. + * We do not copy last byte to userspace if count is odd. + */ + count = (count + 1) / 2; + con_buf16 = (u16 *)con_buf; + + while (count) { + *con_buf16++ = vcs_scr_readw(vc, org++); + count--; + if (++col == maxcol) { + org = screen_pos(vc, pos, viewed); + col = 0; + pos += maxcol; + } + } + + return filled; +} + +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; + unsigned int read; + ssize_t ret; + char *con_buf; + loff_t pos; + bool viewed, attr, uni_mode; + + 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 = -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->event = 0; + read = 0; + ret = 0; + while (count) { + unsigned int this_round, skip = 0; + int size; + + vc = vcs_vc(inode, &viewed); + if (!vc) { + ret = -ENXIO; + break; + } + + /* Check whether we are above size each round, + * as copy_to_user at the end of this loop + * could sleep. + */ + size = vcs_size(vc, attr, uni_mode); + if (size < 0) { + ret = size; + break; + } + 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. + */ + + if (uni_mode) { + ret = vcs_read_buf_uni(vc, con_buf, pos, this_round, + viewed); + if (ret) + break; + } else if (!attr) { + vcs_read_buf_noattr(vc, con_buf, pos, this_round, + viewed); + } else { + this_round = vcs_read_buf(vc, con_buf, pos, this_round, + viewed, &skip); + } + + /* 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 + skip, this_round); + console_lock(); + + if (ret) { + read += this_round - ret; + ret = -EFAULT; + break; + } + buf += this_round; + pos += this_round; + read += this_round; + count -= this_round; + } + *ppos += read; + if (read) + ret = read; +unlock_out: + console_unlock(); + free_page((unsigned long) con_buf); + return ret; +} + +static u16 *vcs_write_buf_noattr(struct vc_data *vc, const char *con_buf, + unsigned int pos, unsigned int count, bool viewed, u16 **org0) +{ + u16 *org; + unsigned int col, maxcol = vc->vc_cols; + + *org0 = org = screen_pos(vc, pos, viewed); + col = pos % maxcol; + pos += maxcol - col; + + while (count > 0) { + unsigned char c = *con_buf++; + + count--; + vcs_scr_writew(vc, + (vcs_scr_readw(vc, org) & 0xff00) | c, org); + org++; + if (++col == maxcol) { + org = screen_pos(vc, pos, viewed); + col = 0; + pos += maxcol; + } + } + + return org; +} + +/* + * Compilers (gcc 10) are unable to optimize the swap in cpu_to_le16. So do it + * the poor man way. + */ +static inline u16 vc_compile_le16(u8 hi, u8 lo) +{ +#ifdef __BIG_ENDIAN + return (lo << 8u) | hi; +#else + return (hi << 8u) | lo; +#endif +} + +static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf, + unsigned int pos, unsigned int count, bool viewed, u16 **org0) +{ + u16 *org; + unsigned int col, maxcol = vc->vc_cols; + unsigned char c; + + /* header */ + if (pos < HEADER_SIZE) { + char header[HEADER_SIZE]; + + getconsxy(vc, header + 2); + while (pos < HEADER_SIZE && count > 0) { + count--; + header[pos++] = *con_buf++; + } + if (!viewed) + putconsxy(vc, header + 2); + } + + if (!count) + return NULL; + + pos -= HEADER_SIZE; + col = (pos/2) % maxcol; + + *org0 = org = screen_pos(vc, pos/2, viewed); + + /* odd pos -- the first single character */ + if (pos & 1) { + count--; + c = *con_buf++; + vcs_scr_writew(vc, vc_compile_le16(c, vcs_scr_readw(vc, org)), + org); + org++; + pos++; + if (++col == maxcol) { + org = screen_pos(vc, pos/2, viewed); + col = 0; + } + } + + pos /= 2; + pos += maxcol - col; + + /* even pos -- handle attr+character pairs */ + while (count > 1) { + unsigned short w; + + w = get_unaligned(((unsigned short *)con_buf)); + vcs_scr_writew(vc, w, org++); + con_buf += 2; + count -= 2; + if (++col == maxcol) { + org = screen_pos(vc, pos, viewed); + col = 0; + pos += maxcol; + } + } + + if (!count) + return org; + + /* odd pos -- the remaining character */ + c = *con_buf++; + vcs_scr_writew(vc, vc_compile_le16(vcs_scr_readw(vc, org) >> 8, c), + org); + + return org; +} + +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; + char *con_buf; + u16 *org0, *org; + unsigned int written; + int size; + ssize_t ret; + loff_t pos; + bool viewed, attr; + + 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(vc, attr, false); + if (size < 0) { + ret = size; + goto unlock_out; + } + ret = -EINVAL; + if (pos < 0 || pos > size) + goto unlock_out; + if (count > size - pos) + count = size - pos; + written = 0; + while (count) { + unsigned int this_round = count; + + 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 vc might have been freed or vcs_size might have changed + * while we slept to grab the user buffer, so recheck. + * Return data written up to now on failure. + */ + vc = vcs_vc(inode, &viewed); + if (!vc) { + if (written) + break; + ret = -ENXIO; + goto unlock_out; + } + size = vcs_size(vc, attr, false); + 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. + */ + + if (attr) + org = vcs_write_buf(vc, con_buf, pos, this_round, + viewed, &org0); + else + org = vcs_write_buf_noattr(vc, con_buf, pos, this_round, + viewed, &org0); + + count -= this_round; + written += this_round; + buf += this_round; + pos += this_round; + if (org) + 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; + + if (poll) { + poll_wait(file, &poll->waitq, wait); + switch (poll->event) { + case VT_UPDATE: + ret = DEFAULT_POLLMASK|EPOLLPRI; + break; + case VT_DEALLOCATE: + ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR; + break; + case 0: + ret = DEFAULT_POLLMASK; + break; + } + } + 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("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; +} -- cgit v1.2.3