Merge tag 'tty-4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial driver updates from Greg KH:
 "Here is the big tty and serial driver pull request for 4.19-rc1.

  It's not all that big, just a number of small serial driver updates
  and fixes, along with some better vt handling for unicode characters
  for those using braille terminals.

  All of these patches have been in linux-next for a long time with no
  reported issues"

* tag 'tty-4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (73 commits)
  tty: serial: 8250: Revert NXP SC16C2552 workaround
  serial: 8250_exar: Read INT0 from slave device, too
  tty: rocket: Fix possible buffer overwrite on register_PCI
  serial: 8250_dw: Add ACPI support for uart on Broadcom SoC
  serial: 8250_dw: always set baud rate in dw8250_set_termios
  dt-bindings: serial: Add binding for uartlite
  tty: serial: uartlite: Add support for suspend and resume
  tty: serial: uartlite: Add clock adaptation
  tty: serial: uartlite: Add structure for private data
  serial: sh-sci: Improve support for separate TEI and DRI interrupts
  serial: sh-sci: Remove SCIx_RZ_SCIFA_REGTYPE
  serial: sh-sci: Allow for compressed SCIF address
  serial: sh-sci: Improve interrupts description
  serial: 8250: Use cached port name directly in messages
  serial: 8250_exar: Drop unused variable in pci_xr17v35x_setup()
  vt: drop unused struct vt_struct
  vt: avoid a VLA in the unicode screen scroll function
  vt: add /dev/vcsu* to devices.txt
  vt: coherence validation code for the unicode screen buffer
  vt: selection: take screen contents from uniscr if available
  ...

4 files changed, 490 insertions, 45 deletions

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index de310621b8e7..88312c6c92cc 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -690,7 +690,35 @@ static void k_dead2(struct vc_data *vc, unsigned char value, char up_flag)
  */
 static void k_dead(struct vc_data *vc, unsigned char value, char up_flag)
 {
-	static const unsigned char ret_diacr[NR_DEAD] = {'`', '\'', '^', '~', '"', ',' };
+	static const unsigned char ret_diacr[NR_DEAD] = {
+		'`',	/* dead_grave */
+		'\'',	/* dead_acute */
+		'^',	/* dead_circumflex */
+		'~',	/* dead_tilda */
+		'"',	/* dead_diaeresis */
+		',',	/* dead_cedilla */
+		'_',	/* dead_macron */
+		'U',	/* dead_breve */
+		'.',	/* dead_abovedot */
+		'*',	/* dead_abovering */
+		'=',	/* dead_doubleacute */
+		'c',	/* dead_caron */
+		'k',	/* dead_ogonek */
+		'i',	/* dead_iota */
+		'#',	/* dead_voiced_sound */
+		'o',	/* dead_semivoiced_sound */
+		'!',	/* dead_belowdot */
+		'?',	/* dead_hook */
+		'+',	/* dead_horn */
+		'-',	/* dead_stroke */
+		')',	/* dead_abovecomma */
+		'(',	/* dead_abovereversedcomma */
+		':',	/* dead_doublegrave */
+		'n',	/* dead_invertedbreve */
+		';',	/* dead_belowcomma */
+		'$',	/* dead_currency */
+		'@',	/* dead_greek */
+	};
 
 	k_deadunicode(vc, ret_diacr[value], up_flag);
 }
diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index 90ea1cc52b7a..07496c711d7d 100644
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -57,11 +57,13 @@ static inline void highlight_pointer(const int where)
 	complement_pos(sel_cons, where);
 }
 
-static u16
+static u32
 sel_pos(int n)
 {
+	if (use_unicode)
+		return screen_glyph_unicode(sel_cons, n / 2);
 	return inverse_translate(sel_cons, screen_glyph(sel_cons, n),
-				use_unicode);
+				0);
 }
 
 /**
@@ -90,7 +92,8 @@ static u32 inwordLut[]={
   0x07FFFFFE, /* lowercase         */
 };
 
-static inline int inword(const u16 c) {
+static inline int inword(const u32 c)
+{
 	return c > 0x7f || (( inwordLut[c>>5] >> (c & 0x1F) ) & 1);
 }
 
@@ -116,14 +119,8 @@ static inline int atedge(const int p, int size_row)
 	return (!(p % size_row)	|| !((p + 2) % size_row));
 }
 
-/* constrain v such that v <= u */
-static inline unsigned short limit(const unsigned short v, const unsigned short u)
-{
-	return (v > u) ? u : v;
-}
-
-/* stores the char in UTF8 and returns the number of bytes used (1-3) */
-static int store_utf8(u16 c, char *p)
+/* stores the char in UTF8 and returns the number of bytes used (1-4) */
+static int store_utf8(u32 c, char *p)
 {
 	if (c < 0x80) {
 		/*  0******* */
@@ -134,13 +131,26 @@ static int store_utf8(u16 c, char *p)
 		p[0] = 0xc0 | (c >> 6);
 		p[1] = 0x80 | (c & 0x3f);
 		return 2;
-    	} else {
+	} else if (c < 0x10000) {
 		/* 1110**** 10****** 10****** */
 		p[0] = 0xe0 | (c >> 12);
 		p[1] = 0x80 | ((c >> 6) & 0x3f);
 		p[2] = 0x80 | (c & 0x3f);
 		return 3;
-    	}
+	} else if (c < 0x110000) {
+		/* 11110*** 10****** 10****** 10****** */
+		p[0] = 0xf0 | (c >> 18);
+		p[1] = 0x80 | ((c >> 12) & 0x3f);
+		p[2] = 0x80 | ((c >> 6) & 0x3f);
+		p[3] = 0x80 | (c & 0x3f);
+		return 4;
+	} else {
+		/* outside Unicode, replace with U+FFFD */
+		p[0] = 0xef;
+		p[1] = 0xbf;
+		p[2] = 0xbd;
+		return 3;
+	}
 }
 
 /**
@@ -160,17 +170,17 @@ int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *t
 	struct tiocl_selection v;
 	char *bp, *obp;
 	int i, ps, pe, multiplier;
-	u16 c;
+	u32 c;
 	int mode;
 
 	poke_blanked_console();
 	if (copy_from_user(&v, sel, sizeof(*sel)))
 		return -EFAULT;
 
-	v.xs = limit(v.xs - 1, vc->vc_cols - 1);
-	v.ys = limit(v.ys - 1, vc->vc_rows - 1);
-	v.xe = limit(v.xe - 1, vc->vc_cols - 1);
-	v.ye = limit(v.ye - 1, vc->vc_rows - 1);
+	v.xs = min_t(u16, v.xs - 1, vc->vc_cols - 1);
+	v.ys = min_t(u16, v.ys - 1, vc->vc_rows - 1);
+	v.xe = min_t(u16, v.xe - 1, vc->vc_cols - 1);
+	v.ye = min_t(u16, v.ye - 1, vc->vc_rows - 1);
 	ps = v.ys * vc->vc_size_row + (v.xs << 1);
 	pe = v.ye * vc->vc_size_row + (v.xe << 1);
 
@@ -279,7 +289,7 @@ int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *t
 	sel_end = new_sel_end;
 
 	/* Allocate a new buffer before freeing the old one ... */
-	multiplier = use_unicode ? 3 : 1;  /* chars can take up to 3 bytes */
+	multiplier = use_unicode ? 4 : 1;  /* chars can take up to 4 bytes */
 	bp = kmalloc_array((sel_end - sel_start) / 2 + 1, multiplier,
 			   GFP_KERNEL);
 	if (!bp) {
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index e4a66e1fd05f..2384ea85ffaf 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -10,6 +10,12 @@
  *	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.
  *
@@ -51,6 +57,26 @@
 
 #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;
@@ -102,7 +128,7 @@ vcs_poll_data_get(struct file *file)
 	poll = kzalloc(sizeof(*poll), GFP_KERNEL);
 	if (!poll)
 		return NULL;
-	poll->cons_num = iminor(file_inode(file)) & 127;
+	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) {
@@ -140,7 +166,7 @@ vcs_poll_data_get(struct file *file)
 static struct vc_data*
 vcs_vc(struct inode *inode, int *viewed)
 {
-	unsigned int currcons = iminor(inode) & 127;
+	unsigned int currcons = console(inode);
 
 	WARN_CONSOLE_UNLOCKED();
 
@@ -164,7 +190,6 @@ static int
 vcs_size(struct inode *inode)
 {
 	int size;
-	int minor = iminor(inode);
 	struct vc_data *vc;
 
 	WARN_CONSOLE_UNLOCKED();
@@ -175,8 +200,12 @@ vcs_size(struct inode *inode)
 
 	size = vc->vc_rows * vc->vc_cols;
 
-	if (minor & 128)
+	if (use_attributes(inode)) {
+		if (use_unicode(inode))
+			return -EOPNOTSUPP;
 		size = 2*size + HEADER_SIZE;
+	} else if (use_unicode(inode))
+		size *= 4;
 	return size;
 }
 
@@ -197,12 +226,10 @@ static ssize_t
 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 {
 	struct inode *inode = file_inode(file);
-	unsigned int currcons = iminor(inode);
 	struct vc_data *vc;
 	struct vcs_poll_data *poll;
-	long pos;
-	long attr, read;
-	int col, maxcol, viewed;
+	long pos, read;
+	int attr, uni_mode, row, col, maxcol, viewed;
 	unsigned short *org = NULL;
 	ssize_t ret;
 	char *con_buf;
@@ -218,7 +245,8 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 	 */
 	console_lock();
 
-	attr = (currcons & 128);
+	uni_mode = use_unicode(inode);
+	attr = use_attributes(inode);
 	ret = -ENXIO;
 	vc = vcs_vc(inode, &viewed);
 	if (!vc)
@@ -227,6 +255,10 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 	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;
@@ -266,7 +298,28 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 		con_buf_start = con_buf0 = con_buf;
 		orig_count = this_round;
 		maxcol = vc->vc_cols;
-		if (!attr) {
+		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;
@@ -375,7 +428,6 @@ static ssize_t
 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 {
 	struct inode *inode = file_inode(file);
-	unsigned int currcons = iminor(inode);
 	struct vc_data *vc;
 	long pos;
 	long attr, size, written;
@@ -396,7 +448,7 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 	 */
 	console_lock();
 
-	attr = (currcons & 128);
+	attr = use_attributes(inode);
 	ret = -ENXIO;
 	vc = vcs_vc(inode, &viewed);
 	if (!vc)
@@ -593,9 +645,15 @@ vcs_fasync(int fd, struct file *file, int on)
 static int
 vcs_open(struct inode *inode, struct file *filp)
 {
-	unsigned int currcons = iminor(inode) & 127;
+	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;
@@ -628,6 +686,8 @@ 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);
 }
@@ -635,6 +695,7 @@ void vcs_make_sysfs(int index)
 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));
 }
 
@@ -647,6 +708,7 @@ int __init vcs_init(void)
 	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);
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 15eb6c829d39..5f1183b0b89d 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -104,6 +104,7 @@
 #include <linux/kdb.h>
 #include <linux/ctype.h>
 #include <linux/bsearch.h>
+#include <linux/gcd.h>
 
 #define MAX_NR_CON_DRIVER 16
 
@@ -317,6 +318,306 @@ void schedule_console_callback(void)
 	schedule_work(&console_work);
 }
 
+/*
+ * Code to manage unicode-based screen buffers
+ */
+
+#ifdef NO_VC_UNI_SCREEN
+/* this disables and optimizes related code away at compile time */
+#define get_vc_uniscr(vc) NULL
+#else
+#define get_vc_uniscr(vc) vc->vc_uni_screen
+#endif
+
+#define VC_UNI_SCREEN_DEBUG 0
+
+typedef uint32_t char32_t;
+
+/*
+ * Our screen buffer is preceded by an array of line pointers so that
+ * scrolling only implies some pointer shuffling.
+ */
+struct uni_screen {
+	char32_t *lines[0];
+};
+
+static struct uni_screen *vc_uniscr_alloc(unsigned int cols, unsigned int rows)
+{
+	struct uni_screen *uniscr;
+	void *p;
+	unsigned int memsize, i;
+
+	/* allocate everything in one go */
+	memsize = cols * rows * sizeof(char32_t);
+	memsize += rows * sizeof(char32_t *);
+	p = kmalloc(memsize, GFP_KERNEL);
+	if (!p)
+		return NULL;
+
+	/* initial line pointers */
+	uniscr = p;
+	p = uniscr->lines + rows;
+	for (i = 0; i < rows; i++) {
+		uniscr->lines[i] = p;
+		p += cols * sizeof(char32_t);
+	}
+	return uniscr;
+}
+
+static void vc_uniscr_set(struct vc_data *vc, struct uni_screen *new_uniscr)
+{
+	kfree(vc->vc_uni_screen);
+	vc->vc_uni_screen = new_uniscr;
+}
+
+static void vc_uniscr_putc(struct vc_data *vc, char32_t uc)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+	if (uniscr)
+		uniscr->lines[vc->vc_y][vc->vc_x] = uc;
+}
+
+static void vc_uniscr_insert(struct vc_data *vc, unsigned int nr)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+	if (uniscr) {
+		char32_t *ln = uniscr->lines[vc->vc_y];
+		unsigned int x = vc->vc_x, cols = vc->vc_cols;
+
+		memmove(&ln[x + nr], &ln[x], (cols - x - nr) * sizeof(*ln));
+		memset32(&ln[x], ' ', nr);
+	}
+}
+
+static void vc_uniscr_delete(struct vc_data *vc, unsigned int nr)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+	if (uniscr) {
+		char32_t *ln = uniscr->lines[vc->vc_y];
+		unsigned int x = vc->vc_x, cols = vc->vc_cols;
+
+		memcpy(&ln[x], &ln[x + nr], (cols - x - nr) * sizeof(*ln));
+		memset32(&ln[cols - nr], ' ', nr);
+	}
+}
+
+static void vc_uniscr_clear_line(struct vc_data *vc, unsigned int x,
+				 unsigned int nr)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+	if (uniscr) {
+		char32_t *ln = uniscr->lines[vc->vc_y];
+
+		memset32(&ln[x], ' ', nr);
+	}
+}
+
+static void vc_uniscr_clear_lines(struct vc_data *vc, unsigned int y,
+				  unsigned int nr)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+	if (uniscr) {
+		unsigned int cols = vc->vc_cols;
+
+		while (nr--)
+			memset32(uniscr->lines[y++], ' ', cols);
+	}
+}
+
+static void vc_uniscr_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
+			     enum con_scroll dir, unsigned int nr)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+	if (uniscr) {
+		unsigned int i, j, k, sz, d, clear;
+
+		sz = b - t;
+		clear = b - nr;
+		d = nr;
+		if (dir == SM_DOWN) {
+			clear = t;
+			d = sz - nr;
+		}
+		for (i = 0; i < gcd(d, sz); i++) {
+			char32_t *tmp = uniscr->lines[t + i];
+			j = i;
+			while (1) {
+				k = j + d;
+				if (k >= sz)
+					k -= sz;
+				if (k == i)
+					break;
+				uniscr->lines[t + j] = uniscr->lines[t + k];
+				j = k;
+			}
+			uniscr->lines[t + j] = tmp;
+		}
+		vc_uniscr_clear_lines(vc, clear, nr);
+	}
+}
+
+static void vc_uniscr_copy_area(struct uni_screen *dst,
+				unsigned int dst_cols,
+				unsigned int dst_rows,
+				struct uni_screen *src,
+				unsigned int src_cols,
+				unsigned int src_top_row,
+				unsigned int src_bot_row)
+{
+	unsigned int dst_row = 0;
+
+	if (!dst)
+		return;
+
+	while (src_top_row < src_bot_row) {
+		char32_t *src_line = src->lines[src_top_row];
+		char32_t *dst_line = dst->lines[dst_row];
+
+		memcpy(dst_line, src_line, src_cols * sizeof(char32_t));
+		if (dst_cols - src_cols)
+			memset32(dst_line + src_cols, ' ', dst_cols - src_cols);
+		src_top_row++;
+		dst_row++;
+	}
+	while (dst_row < dst_rows) {
+		char32_t *dst_line = dst->lines[dst_row];
+
+		memset32(dst_line, ' ', dst_cols);
+		dst_row++;
+	}
+}
+
+/*
+ * Called from vcs_read() to make sure unicode screen retrieval is possible.
+ * This will initialize the unicode screen buffer if not already done.
+ * This returns 0 if OK, or a negative error code otherwise.
+ * In particular, -ENODATA is returned if the console is not in UTF-8 mode.
+ */
+int vc_uniscr_check(struct vc_data *vc)
+{
+	struct uni_screen *uniscr;
+	unsigned short *p;
+	int x, y, mask;
+
+	if (__is_defined(NO_VC_UNI_SCREEN))
+		return -EOPNOTSUPP;
+
+	WARN_CONSOLE_UNLOCKED();
+
+	if (!vc->vc_utf)
+		return -ENODATA;
+
+	if (vc->vc_uni_screen)
+		return 0;
+
+	uniscr = vc_uniscr_alloc(vc->vc_cols, vc->vc_rows);
+	if (!uniscr)
+		return -ENOMEM;
+
+	/*
+	 * Let's populate it initially with (imperfect) reverse translation.
+	 * This is the next best thing we can do short of having it enabled
+	 * from the start even when no users rely on this functionality. True
+	 * unicode content will be available after a complete screen refresh.
+	 */
+	p = (unsigned short *)vc->vc_origin;
+	mask = vc->vc_hi_font_mask | 0xff;
+	for (y = 0; y < vc->vc_rows; y++) {
+		char32_t *line = uniscr->lines[y];
+		for (x = 0; x < vc->vc_cols; x++) {
+			u16 glyph = scr_readw(p++) & mask;
+			line[x] = inverse_translate(vc, glyph, true);
+		}
+	}
+
+	vc->vc_uni_screen = uniscr;
+	return 0;
+}
+
+/*
+ * Called from vcs_read() to get the unicode data from the screen.
+ * This must be preceded by a successful call to vc_uniscr_check() once
+ * the console lock has been taken.
+ */
+void vc_uniscr_copy_line(struct vc_data *vc, void *dest, int viewed,
+			 unsigned int row, unsigned int col, unsigned int nr)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+	int offset = row * vc->vc_size_row + col * 2;
+	unsigned long pos;
+
+	BUG_ON(!uniscr);
+
+	pos = (unsigned long)screenpos(vc, offset, viewed);
+	if (pos >= vc->vc_origin && pos < vc->vc_scr_end) {
+		/*
+		 * Desired position falls in the main screen buffer.
+		 * However the actual row/col might be different if
+		 * scrollback is active.
+		 */
+		row = (pos - vc->vc_origin) / vc->vc_size_row;
+		col = ((pos - vc->vc_origin) % vc->vc_size_row) / 2;
+		memcpy(dest, &uniscr->lines[row][col], nr * sizeof(char32_t));
+	} else {
+		/*
+		 * Scrollback is active. For now let's simply backtranslate
+		 * the screen glyphs until the unicode screen buffer does
+		 * synchronize with console display drivers for a scrollback
+		 * buffer of its own.
+		 */
+		u16 *p = (u16 *)pos;
+		int mask = vc->vc_hi_font_mask | 0xff;
+		char32_t *uni_buf = dest;
+		while (nr--) {
+			u16 glyph = scr_readw(p++) & mask;
+			*uni_buf++ = inverse_translate(vc, glyph, true);
+		}
+	}
+}
+
+/* this is for validation and debugging only */
+static void vc_uniscr_debug_check(struct vc_data *vc)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+	unsigned short *p;
+	int x, y, mask;
+
+	if (!VC_UNI_SCREEN_DEBUG || !uniscr)
+		return;
+
+	WARN_CONSOLE_UNLOCKED();
+
+	/*
+	 * Make sure our unicode screen translates into the same glyphs
+	 * as the actual screen. This is brutal indeed.
+	 */
+	p = (unsigned short *)vc->vc_origin;
+	mask = vc->vc_hi_font_mask | 0xff;
+	for (y = 0; y < vc->vc_rows; y++) {
+		char32_t *line = uniscr->lines[y];
+		for (x = 0; x < vc->vc_cols; x++) {
+			u16 glyph = scr_readw(p++) & mask;
+			char32_t uc = line[x];
+			int tc = conv_uni_to_pc(vc, uc);
+			if (tc == -4)
+				tc = conv_uni_to_pc(vc, 0xfffd);
+			if (tc == -4)
+				tc = conv_uni_to_pc(vc, '?');
+			if (tc != glyph)
+				pr_err_ratelimited(
+					"%s: mismatch at %d,%d: glyph=%#x tc=%#x\n",
+					__func__, x, y, glyph, tc);
+		}
+	}
+}
+
+
 static void con_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
 		enum con_scroll dir, unsigned int nr)
 {
@@ -326,6 +627,7 @@ static void con_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
 		nr = b - t - 1;
 	if (b > vc->vc_rows || t >= b || nr < 1)
 		return;
+	vc_uniscr_scroll(vc, t, b, dir, nr);
 	if (con_is_visible(vc) && vc->vc_sw->con_scroll(vc, t, b, dir, nr))
 		return;
 
@@ -533,6 +835,7 @@ static void insert_char(struct vc_data *vc, unsigned int nr)
 {
 	unsigned short *p = (unsigned short *) vc->vc_pos;
 
+	vc_uniscr_insert(vc, nr);
 	scr_memmovew(p + nr, p, (vc->vc_cols - vc->vc_x - nr) * 2);
 	scr_memsetw(p, vc->vc_video_erase_char, nr * 2);
 	vc->vc_need_wrap = 0;
@@ -545,6 +848,7 @@ static void delete_char(struct vc_data *vc, unsigned int nr)
 {
 	unsigned short *p = (unsigned short *) vc->vc_pos;
 
+	vc_uniscr_delete(vc, nr);
 	scr_memcpyw(p, p + nr, (vc->vc_cols - vc->vc_x - nr) * 2);
 	scr_memsetw(p + vc->vc_cols - vc->vc_x - nr, vc->vc_video_erase_char,
 			nr * 2);
@@ -845,10 +1149,11 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 {
 	unsigned long old_origin, new_origin, new_scr_end, rlth, rrem, err = 0;
 	unsigned long end;
-	unsigned int old_rows, old_row_size;
+	unsigned int old_rows, old_row_size, first_copied_row;
 	unsigned int new_cols, new_rows, new_row_size, new_screen_size;
 	unsigned int user;
 	unsigned short *newscreen;
+	struct uni_screen *new_uniscr = NULL;
 
 	WARN_CONSOLE_UNLOCKED();
 
@@ -875,6 +1180,14 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 	if (!newscreen)
 		return -ENOMEM;
 
+	if (get_vc_uniscr(vc)) {
+		new_uniscr = vc_uniscr_alloc(new_cols, new_rows);
+		if (!new_uniscr) {
+			kfree(newscreen);
+			return -ENOMEM;
+		}
+	}
+
 	if (vc == sel_cons)
 		clear_selection();
 
@@ -884,6 +1197,7 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 	err = resize_screen(vc, new_cols, new_rows, user);
 	if (err) {
 		kfree(newscreen);
+		kfree(new_uniscr);
 		return err;
 	}
 
@@ -904,18 +1218,24 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 			 * Cursor near the bottom, copy contents from the
 			 * bottom of buffer
 			 */
-			old_origin += (old_rows - new_rows) * old_row_size;
+			first_copied_row = (old_rows - new_rows);
 		} else {
 			/*
 			 * Cursor is in no man's land, copy 1/2 screenful
 			 * from the top and bottom of cursor position
 			 */
-			old_origin += (vc->vc_y - new_rows/2) * old_row_size;
+			first_copied_row = (vc->vc_y - new_rows/2);
 		}
-	}
-
+		old_origin += first_copied_row * old_row_size;
+	} else
+		first_copied_row = 0;
 	end = old_origin + old_row_size * min(old_rows, new_rows);
 
+	vc_uniscr_copy_area(new_uniscr, new_cols, new_rows,
+			    get_vc_uniscr(vc), rlth/2, first_copied_row,
+			    min(old_rows, new_rows));
+	vc_uniscr_set(vc, new_uniscr);
+
 	update_attr(vc);
 
 	while (old_origin < end) {
@@ -1013,6 +1333,7 @@ struct vc_data *vc_deallocate(unsigned int currcons)
 		vc->vc_sw->con_deinit(vc);
 		put_pid(vc->vt_pid);
 		module_put(vc->vc_sw->owner);
+		vc_uniscr_set(vc, NULL);
 		kfree(vc->vc_screenbuf);
 		vc_cons[currcons].d = NULL;
 	}
@@ -1171,15 +1492,22 @@ static void csi_J(struct vc_data *vc, int vpar)
 
 	switch (vpar) {
 		case 0:	/* erase from cursor to end of display */
+			vc_uniscr_clear_line(vc, vc->vc_x,
+					     vc->vc_cols - vc->vc_x);
+			vc_uniscr_clear_lines(vc, vc->vc_y + 1,
+					      vc->vc_rows - vc->vc_y - 1);
 			count = (vc->vc_scr_end - vc->vc_pos) >> 1;
 			start = (unsigned short *)vc->vc_pos;
 			break;
 		case 1:	/* erase from start to cursor */
+			vc_uniscr_clear_line(vc, 0, vc->vc_x + 1);
+			vc_uniscr_clear_lines(vc, 0, vc->vc_y);
 			count = ((vc->vc_pos - vc->vc_origin) >> 1) + 1;
 			start = (unsigned short *)vc->vc_origin;
 			break;
 		case 2: /* erase whole display */
 		case 3: /* (and scrollback buffer later) */
+			vc_uniscr_clear_lines(vc, 0, vc->vc_rows);
 			count = vc->vc_cols * vc->vc_rows;
 			start = (unsigned short *)vc->vc_origin;
 			break;
@@ -1200,25 +1528,27 @@ static void csi_J(struct vc_data *vc, int vpar)
 static void csi_K(struct vc_data *vc, int vpar)
 {
 	unsigned int count;
-	unsigned short * start;
+	unsigned short *start = (unsigned short *)vc->vc_pos;
+	int offset;
 
 	switch (vpar) {
 		case 0:	/* erase from cursor to end of line */
+			offset = 0;
 			count = vc->vc_cols - vc->vc_x;
-			start = (unsigned short *)vc->vc_pos;
 			break;
 		case 1:	/* erase from start of line to cursor */
-			start = (unsigned short *)(vc->vc_pos - (vc->vc_x << 1));
+			offset = -vc->vc_x;
 			count = vc->vc_x + 1;
 			break;
 		case 2: /* erase whole line */
-			start = (unsigned short *)(vc->vc_pos - (vc->vc_x << 1));
+			offset = -vc->vc_x;
 			count = vc->vc_cols;
 			break;
 		default:
 			return;
 	}
-	scr_memsetw(start, vc->vc_video_erase_char, 2 * count);
+	vc_uniscr_clear_line(vc, vc->vc_x + offset, count);
+	scr_memsetw(start + offset, vc->vc_video_erase_char, 2 * count);
 	vc->vc_need_wrap = 0;
 	if (con_should_update(vc))
 		do_update_region(vc, (unsigned long) start, count);
@@ -1232,6 +1562,7 @@ static void csi_X(struct vc_data *vc, int vpar) /* erase the following vpar posi
 		vpar++;
 	count = (vpar > vc->vc_cols - vc->vc_x) ? (vc->vc_cols - vc->vc_x) : vpar;
 
+	vc_uniscr_clear_line(vc, vc->vc_x, count);
 	scr_memsetw((unsigned short *)vc->vc_pos, vc->vc_video_erase_char, 2 * count);
 	if (con_should_update(vc))
 		vc->vc_sw->con_clear(vc, vc->vc_y, vc->vc_x, 1, count);
@@ -2188,7 +2519,7 @@ static void con_flush(struct vc_data *vc, unsigned long draw_from,
 /* acquires console_lock */
 static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int count)
 {
-	int c, tc, ok, n = 0, draw_x = -1;
+	int c, next_c, tc, ok, n = 0, draw_x = -1;
 	unsigned int currcons;
 	unsigned long draw_from = 0, draw_to = 0;
 	struct vc_data *vc;
@@ -2382,6 +2713,7 @@ rescan_last_byte:
 				con_flush(vc, draw_from, draw_to, &draw_x);
 			}
 
+			next_c = c;
 			while (1) {
 				if (vc->vc_need_wrap || vc->vc_decim)
 					con_flush(vc, draw_from, draw_to,
@@ -2392,6 +2724,7 @@ rescan_last_byte:
 				}
 				if (vc->vc_decim)
 					insert_char(vc, 1);
+				vc_uniscr_putc(vc, next_c);
 				scr_writew(himask ?
 					     ((vc_attr << 8) & ~himask) + ((tc & 0x100) ? himask : 0) + (tc & 0xff) :
 					     (vc_attr << 8) + tc,
@@ -2412,6 +2745,7 @@ rescan_last_byte:
 
 				tc = conv_uni_to_pc(vc, ' '); /* A space is printed in the second column */
 				if (tc < 0) tc = ' ';
+				next_c = ' ';
 			}
 			notify_write(vc, c);
 
@@ -2431,6 +2765,7 @@ rescan_last_byte:
 		do_con_trol(tty, vc, orig);
 	}
 	con_flush(vc, draw_from, draw_to, &draw_x);
+	vc_uniscr_debug_check(vc);
 	console_conditional_schedule();
 	console_unlock();
 	notify_update(vc);
@@ -4257,6 +4592,16 @@ u16 screen_glyph(struct vc_data *vc, int offset)
 }
 EXPORT_SYMBOL_GPL(screen_glyph);
 
+u32 screen_glyph_unicode(struct vc_data *vc, int n)
+{
+	struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+	if (uniscr)
+		return uniscr->lines[n / vc->vc_cols][n % vc->vc_cols];
+	return inverse_translate(vc, screen_glyph(vc, n * 2), 1);
+}
+EXPORT_SYMBOL_GPL(screen_glyph_unicode);
+
 /* used by vcs - note the word offset */
 unsigned short *screen_pos(struct vc_data *vc, int w_offset, int viewed)
 {