1 files changed, 30 insertions, 11 deletions

diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c
index 4d6c5327471a..f54e6fdf08e2 100644
--- a/drivers/firmware/efi/earlycon.c
+++ b/drivers/firmware/efi/earlycon.c
@@ -10,11 +10,14 @@
 #include <linux/kernel.h>
 #include <linux/serial_core.h>
 #include <linux/screen_info.h>
+#include <linux/string.h>
 
 #include <asm/early_ioremap.h>
 
 static const struct console *earlycon_console __initdata;
 static const struct font_desc *font;
+static u16 cur_line_y, max_line_y;
+static u32 efi_x_array[1024];
 static u32 efi_x, efi_y;
 static u64 fb_base;
 static bool fb_wb;
@@ -85,9 +88,17 @@ static void efi_earlycon_clear_scanline(unsigned int y)
 static void efi_earlycon_scroll_up(void)
 {
 	unsigned long *dst, *src;
+	u16 maxlen = 0;
 	u16 len;
 	u32 i, height;
 
+	/* Find the cached maximum x coordinate */
+	for (i = 0; i < max_line_y; i++) {
+		if (efi_x_array[i] > maxlen)
+			maxlen = efi_x_array[i];
+	}
+	maxlen *= 4;
+
 	len = screen_info.lfb_linelength;
 	height = screen_info.lfb_height;
 
@@ -102,7 +113,7 @@ static void efi_earlycon_scroll_up(void)
 			return;
 		}
 
-		memmove(dst, src, len);
+		memmove(dst, src, maxlen);
 
 		efi_earlycon_unmap(src, len);
 		efi_earlycon_unmap(dst, len);
@@ -135,6 +146,7 @@ static void
 efi_earlycon_write(struct console *con, const char *str, unsigned int num)
 {
 	struct screen_info *si;
+	u32 cur_efi_x = efi_x;
 	unsigned int len;
 	const char *s;
 	void *dst;
@@ -143,16 +155,10 @@ efi_earlycon_write(struct console *con, const char *str, unsigned int num)
 	len = si->lfb_linelength;
 
 	while (num) {
-		unsigned int linemax;
-		unsigned int h, count = 0;
-
-		for (s = str; *s && *s != '\n'; s++) {
-			if (count == num)
-				break;
-			count++;
-		}
+		unsigned int linemax = (si->lfb_width - efi_x) / font->width;
+		unsigned int h, count;
 
-		linemax = (si->lfb_width - efi_x) / font->width;
+		count = strnchrnul(str, num, '\n') - str;
 		if (count > linemax)
 			count = linemax;
 
@@ -181,6 +187,7 @@ efi_earlycon_write(struct console *con, const char *str, unsigned int num)
 		str += count;
 
 		if (num > 0 && *s == '\n') {
+			cur_efi_x = efi_x;
 			efi_x = 0;
 			efi_y += font->height;
 			str++;
@@ -188,6 +195,7 @@ efi_earlycon_write(struct console *con, const char *str, unsigned int num)
 		}
 
 		if (efi_x + font->width > si->lfb_width) {
+			cur_efi_x = efi_x;
 			efi_x = 0;
 			efi_y += font->height;
 		}
@@ -195,6 +203,9 @@ efi_earlycon_write(struct console *con, const char *str, unsigned int num)
 		if (efi_y + font->height > si->lfb_height) {
 			u32 i;
 
+			efi_x_array[cur_line_y] = cur_efi_x;
+			cur_line_y = (cur_line_y + 1) % max_line_y;
+
 			efi_y -= font->height;
 			efi_earlycon_scroll_up();
 
@@ -235,7 +246,15 @@ static int __init efi_earlycon_setup(struct earlycon_device *device,
 	if (!font)
 		return -ENODEV;
 
-	efi_y = rounddown(yres, font->height) - font->height;
+	/* Fill the cache with maximum possible value of x coordinate */
+	memset32(efi_x_array, rounddown(xres, font->width), ARRAY_SIZE(efi_x_array));
+	efi_y = rounddown(yres, font->height);
+
+	/* Make sure we have cache for the x coordinate for the full screen */
+	max_line_y = efi_y / font->height + 1;
+	cur_line_y = 0;
+
+	efi_y -= font->height;
 	for (i = 0; i < (yres - efi_y) / font->height; i++)
 		efi_earlycon_scroll_up();