x86/efi: Add EFI framebuffer earlyprintk support

It's incredibly difficult to diagnose early EFI boot issues without special hardware because earlyprintk=vga doesn't work on EFI systems. Add support for writing to the EFI framebuffer, via earlyprintk=efi, which will actually give users a chance of providing debug output. Cc: H. Peter Anvin <hpa@zytor.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Jones <pjones@redhat.com> Signed-off-by: Matt Fleming <matt.fleming@intel.com>

x86/efi: Add EFI framebuffer earlyprintk support
It's incredibly difficult to diagnose early EFI boot issues without special hardware because earlyprintk=vga doesn't work on EFI systems. Add support for writing to the EFI framebuffer, via earlyprintk=efi, which will actually give users a chance of providing debug output. Cc: H. Peter Anvin <hpa@zytor.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Jones <pjones@redhat.com> Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Matt Fleming
1 parent c158c3bf59
Showing 6 changed files with 216 additions and 3 deletions Side-by-side Diff
Documentation/kernel-parameters.txt
arch/x86/Kconfig.debug
arch/x86/include/asm/efi.h
arch/x86/kernel/early_printk.c
arch/x86/platform/efi/Makefile
arch/x86/platform/efi/early_printk.c
@@ -792,6 +792,7 @@
  
 	earlyprintk=	[X86,SH,BLACKFIN,ARM]
 			earlyprintk=vga
+			earlyprintk=efi
 			earlyprintk=xen
 			earlyprintk=serial[,ttySn[,baudrate]]
 			earlyprintk=serial[,0x...[,baudrate]]
@@ -805,7 +806,8 @@
 			Append ",keep" to not disable it when the real console
 			takes over.
  
-			Only vga or serial or usb debug port at a time.
+			Only one of vga, efi, serial, or usb debug port can
+			be used at a time.
  
 			Currently only ttyS0 and ttyS1 may be specified by
 			name.  Other I/O ports may be explicitly specified
@@ -819,8 +821,8 @@
 			Interaction with the standard serial driver is not
 			very good.
  
-			The VGA output is eventually overwritten by the real
-			console.
+			The VGA and EFI output is eventually overwritten by
+			the real console.
  
 			The xen output can only be used by Xen PV guests.
  
@@ -59,6 +59,16 @@
 	  with klogd/syslogd or the X server. You should normally N here,
 	  unless you want to debug such a crash. You need usb debug device.
  
+config EARLY_PRINTK_EFI
+	bool "Early printk via the EFI framebuffer"
+	depends on EFI && EARLY_PRINTK
+	select FONT_SUPPORT
+	---help---
+	  Write kernel log output directly into the EFI framebuffer.
+
+	  This is useful for kernel debugging when your machine crashes very
+	  early before the console code is initialized.
+
 config X86_PTDUMP
 	bool "Export kernel pagetable layout to userspace via debugfs"
 	depends on DEBUG_KERNEL
@@ -109,6 +109,8 @@
 	return IS_ENABLED(CONFIG_X86_64) == efi_enabled(EFI_64BIT);
 }
  
+extern struct console early_efi_console;
+
 #else
 /*
  * IF EFI is not configured, have the EFI calls return -ENOSYS.
@@ -17,6 +17,8 @@
 #include <asm/mrst.h>
 #include <asm/pgtable.h>
 #include <linux/usb/ehci_def.h>
+#include <linux/efi.h>
+#include <asm/efi.h>
  
 /* Simple VGA output */
 #define VGABASE		(__ISA_IO_base + 0xb8000)
@@ -234,6 +236,11 @@
 			early_console_register(&early_hsu_console, keep);
 		}
 #endif
+#ifdef CONFIG_EARLY_PRINTK_EFI
+		if (!strncmp(buf, "efi", 3))
+			early_console_register(&early_efi_console, keep);
+#endif
+
 		buf++;
 	}
 	return 0;
 obj-$(CONFIG_EFI) 		+= efi.o efi_$(BITS).o efi_stub_$(BITS).o
 obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o
+obj-$(CONFIG_EARLY_PRINTK_EFI)	+= early_printk.o
+/*
+ * Copyright (C) 2013 Intel Corporation; author Matt Fleming
+ *
+ *  This file is part of the Linux kernel, and is made available under
+ *  the terms of the GNU General Public License version 2.
+ */
+
+#include <linux/console.h>
+#include <linux/efi.h>
+#include <linux/font.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <asm/setup.h>
+
+static const struct font_desc *font;
+static u32 efi_x, efi_y;
+
+static __init void early_efi_clear_scanline(unsigned int y)
+{
+	unsigned long base, *dst;
+	u16 len;
+
+	base = boot_params.screen_info.lfb_base;
+	len = boot_params.screen_info.lfb_linelength;
+
+	dst = early_ioremap(base + y*len, len);
+	if (!dst)
+		return;
+
+	memset(dst, 0, len);
+	early_iounmap(dst, len);
+}
+
+static __init void early_efi_scroll_up(void)
+{
+	unsigned long base, *dst, *src;
+	u16 len;
+	u32 i, height;
+
+	base = boot_params.screen_info.lfb_base;
+	len = boot_params.screen_info.lfb_linelength;
+	height = boot_params.screen_info.lfb_height;
+
+	for (i = 0; i < height - font->height; i++) {
+		dst = early_ioremap(base + i*len, len);
+		if (!dst)
+			return;
+
+		src = early_ioremap(base + (i + font->height) * len, len);
+		if (!src) {
+			early_iounmap(dst, len);
+			return;
+		}
+
+		memmove(dst, src, len);
+
+		early_iounmap(src, len);
+		early_iounmap(dst, len);
+	}
+}
+
+static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
+{
+	const u32 color_black = 0x00000000;
+	const u32 color_white = 0x00ffffff;
+	const u8 *src;
+	u8 s8;
+	int m;
+
+	src = font->data + c * font->height;
+	s8 = *(src + h);
+
+	for (m = 0; m < 8; m++) {
+		if ((s8 >> (7 - m)) & 1)
+			*dst = color_white;
+		else
+			*dst = color_black;
+		dst++;
+	}
+}
+
+static __init void
+early_efi_write(struct console *con, const char *str, unsigned int num)
+{
+	struct screen_info *si;
+	unsigned long base;
+	unsigned int len;
+	const char *s;
+	void *dst;
+
+	base = boot_params.screen_info.lfb_base;
+	si = &boot_params.screen_info;
+	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++;
+		}
+
+		linemax = (si->lfb_width - efi_x) / font->width;
+		if (count > linemax)
+			count = linemax;
+
+		for (h = 0; h < font->height; h++) {
+			unsigned int n, x;
+
+			dst = early_ioremap(base + (efi_y + h) * len, len);
+			if (!dst)
+				return;
+
+			s = str;
+			n = count;
+			x = efi_x;
+
+			while (n-- > 0) {
+				early_efi_write_char(dst + x*4, *s, h);
+				x += font->width;
+				s++;
+			}
+
+			early_iounmap(dst, len);
+		}
+
+		num -= count;
+		efi_x += count * font->width;
+		str += count;
+
+		if (num > 0 && *s == '\n') {
+			efi_x = 0;
+			efi_y += font->height;
+			str++;
+			num--;
+		}
+
+		if (efi_x >= si->lfb_width) {
+			efi_x = 0;
+			efi_y += font->height;
+		}
+
+		if (efi_y + font->height >= si->lfb_height) {
+			u32 i;
+
+			efi_y -= font->height;
+			early_efi_scroll_up();
+
+			for (i = 0; i < font->height; i++)
+				early_efi_clear_scanline(efi_y + i);
+		}
+	}
+}
+
+static __init int early_efi_setup(struct console *con, char *options)
+{
+	struct screen_info *si;
+	u16 xres, yres;
+	u32 i;
+
+	si = &boot_params.screen_info;
+	xres = si->lfb_width;
+	yres = si->lfb_height;
+
+	/*
+	 * early_efi_write_char() implicitly assumes a framebuffer with
+	 * 32-bits per pixel.
+	 */
+	if (si->lfb_depth != 32)
+		return -ENODEV;
+
+	font = get_default_font(xres, yres, -1, -1);
+	if (!font)
+		return -ENODEV;
+
+	efi_y = rounddown(yres, font->height) - font->height;
+	for (i = 0; i < (yres - efi_y) / font->height; i++)
+		early_efi_scroll_up();
+
+	return 0;
+}
+
+struct console early_efi_console = {
+	.name =		"earlyefi",
+	.write =	early_efi_write,
+	.setup =	early_efi_setup,
+	.flags =	CON_PRINTBUFFER,
+	.index =	-1,
+};
...	...	@@ -792,6 +792,7 @@
792	792
793	793	earlyprintk= [X86,SH,BLACKFIN,ARM]
794	794	earlyprintk=vga
	795	+ earlyprintk=efi
795	796	earlyprintk=xen
796	797	earlyprintk=serial[,ttySn[,baudrate]]
797	798	earlyprintk=serial[,0x...[,baudrate]]
...	...	@@ -805,7 +806,8 @@
805	806	Append ",keep" to not disable it when the real console
806	807	takes over.
807	808
808		- Only vga or serial or usb debug port at a time.
	809	+ Only one of vga, efi, serial, or usb debug port can
	810	+ be used at a time.
809	811
810	812	Currently only ttyS0 and ttyS1 may be specified by
811	813	name. Other I/O ports may be explicitly specified
...	...	@@ -819,8 +821,8 @@
819	821	Interaction with the standard serial driver is not
820	822	very good.
821	823
822		- The VGA output is eventually overwritten by the real
823		- console.
	824	+ The VGA and EFI output is eventually overwritten by
	825	+ the real console.
824	826
825	827	The xen output can only be used by Xen PV guests.
826	828
...	...	@@ -59,6 +59,16 @@
59	59	with klogd/syslogd or the X server. You should normally N here,
60	60	unless you want to debug such a crash. You need usb debug device.
61	61
	62	+config EARLY_PRINTK_EFI
	63	+ bool "Early printk via the EFI framebuffer"
	64	+ depends on EFI && EARLY_PRINTK
	65	+ select FONT_SUPPORT
	66	+ ---help---
	67	+ Write kernel log output directly into the EFI framebuffer.
	68	+
	69	+ This is useful for kernel debugging when your machine crashes very
	70	+ early before the console code is initialized.
	71	+
62	72	config X86_PTDUMP
63	73	bool "Export kernel pagetable layout to userspace via debugfs"
64	74	depends on DEBUG_KERNEL
...	...	@@ -109,6 +109,8 @@
109	109	return IS_ENABLED(CONFIG_X86_64) == efi_enabled(EFI_64BIT);
110	110	}
111	111
	112	+extern struct console early_efi_console;
	113	+
112	114	#else
113	115	/*
114	116	* IF EFI is not configured, have the EFI calls return -ENOSYS.
...	...	@@ -17,6 +17,8 @@
17	17	#include <asm/mrst.h>
18	18	#include <asm/pgtable.h>
19	19	#include <linux/usb/ehci_def.h>
	20	+#include <linux/efi.h>
	21	+#include <asm/efi.h>
20	22
21	23	/* Simple VGA output */
22	24	#define VGABASE (__ISA_IO_base + 0xb8000)
...	...	@@ -234,6 +236,11 @@
234	236	early_console_register(&early_hsu_console, keep);
235	237	}
236	238	#endif
	239	+#ifdef CONFIG_EARLY_PRINTK_EFI
	240	+ if (!strncmp(buf, "efi", 3))
	241	+ early_console_register(&early_efi_console, keep);
	242	+#endif
	243	+
237	244	buf++;
238	245	}
239	246	return 0;
1	1	obj-$(CONFIG_EFI) += efi.o efi_$(BITS).o efi_stub_$(BITS).o
2	2	obj-$(CONFIG_ACPI_BGRT) += efi-bgrt.o
	3	+obj-$(CONFIG_EARLY_PRINTK_EFI) += early_printk.o
	1	+/*
	2	+ * Copyright (C) 2013 Intel Corporation; author Matt Fleming
	3	+ *
	4	+ * This file is part of the Linux kernel, and is made available under
	5	+ * the terms of the GNU General Public License version 2.
	6	+ */
	7	+
	8	+#include <linux/console.h>
	9	+#include <linux/efi.h>
	10	+#include <linux/font.h>
	11	+#include <linux/io.h>
	12	+#include <linux/kernel.h>
	13	+#include <asm/setup.h>
	14	+
	15	+static const struct font_desc *font;
	16	+static u32 efi_x, efi_y;
	17	+
	18	+static __init void early_efi_clear_scanline(unsigned int y)
	19	+{
	20	+ unsigned long base, *dst;
	21	+ u16 len;
	22	+
	23	+ base = boot_params.screen_info.lfb_base;
	24	+ len = boot_params.screen_info.lfb_linelength;
	25	+
	26	+ dst = early_ioremap(base + y*len, len);
	27	+ if (!dst)
	28	+ return;
	29	+
	30	+ memset(dst, 0, len);
	31	+ early_iounmap(dst, len);
	32	+}
	33	+
	34	+static __init void early_efi_scroll_up(void)
	35	+{
	36	+ unsigned long base, dst, src;
	37	+ u16 len;
	38	+ u32 i, height;
	39	+
	40	+ base = boot_params.screen_info.lfb_base;
	41	+ len = boot_params.screen_info.lfb_linelength;
	42	+ height = boot_params.screen_info.lfb_height;
	43	+
	44	+ for (i = 0; i < height - font->height; i++) {
	45	+ dst = early_ioremap(base + i*len, len);
	46	+ if (!dst)
	47	+ return;
	48	+
	49	+ src = early_ioremap(base + (i + font->height) * len, len);
	50	+ if (!src) {
	51	+ early_iounmap(dst, len);
	52	+ return;
	53	+ }
	54	+
	55	+ memmove(dst, src, len);
	56	+
	57	+ early_iounmap(src, len);
	58	+ early_iounmap(dst, len);
	59	+ }
	60	+}
	61	+
	62	+static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
	63	+{
	64	+ const u32 color_black = 0x00000000;
	65	+ const u32 color_white = 0x00ffffff;
	66	+ const u8 *src;
	67	+ u8 s8;
	68	+ int m;
	69	+
	70	+ src = font->data + c * font->height;
	71	+ s8 = *(src + h);
	72	+
	73	+ for (m = 0; m < 8; m++) {
	74	+ if ((s8 >> (7 - m)) & 1)
	75	+ *dst = color_white;
	76	+ else
	77	+ *dst = color_black;
	78	+ dst++;
	79	+ }
	80	+}
	81	+
	82	+static __init void
	83	+early_efi_write(struct console con, const char str, unsigned int num)
	84	+{
	85	+ struct screen_info *si;
	86	+ unsigned long base;
	87	+ unsigned int len;
	88	+ const char *s;
	89	+ void *dst;
	90	+
	91	+ base = boot_params.screen_info.lfb_base;
	92	+ si = &boot_params.screen_info;
	93	+ len = si->lfb_linelength;
	94	+
	95	+ while (num) {
	96	+ unsigned int linemax;
	97	+ unsigned int h, count = 0;
	98	+
	99	+ for (s = str; s && s != '\n'; s++) {
	100	+ if (count == num)
	101	+ break;
	102	+ count++;
	103	+ }
	104	+
	105	+ linemax = (si->lfb_width - efi_x) / font->width;
	106	+ if (count > linemax)
	107	+ count = linemax;
	108	+
	109	+ for (h = 0; h < font->height; h++) {
	110	+ unsigned int n, x;
	111	+
	112	+ dst = early_ioremap(base + (efi_y + h) * len, len);
	113	+ if (!dst)
	114	+ return;
	115	+
	116	+ s = str;
	117	+ n = count;
	118	+ x = efi_x;
	119	+
	120	+ while (n-- > 0) {
	121	+ early_efi_write_char(dst + x4, s, h);
	122	+ x += font->width;
	123	+ s++;
	124	+ }
	125	+
	126	+ early_iounmap(dst, len);
	127	+ }
	128	+
	129	+ num -= count;
	130	+ efi_x += count * font->width;
	131	+ str += count;
	132	+
	133	+ if (num > 0 && *s == '\n') {
	134	+ efi_x = 0;
	135	+ efi_y += font->height;
	136	+ str++;
	137	+ num--;
	138	+ }
	139	+
	140	+ if (efi_x >= si->lfb_width) {
	141	+ efi_x = 0;
	142	+ efi_y += font->height;
	143	+ }
	144	+
	145	+ if (efi_y + font->height >= si->lfb_height) {
	146	+ u32 i;
	147	+
	148	+ efi_y -= font->height;
	149	+ early_efi_scroll_up();
	150	+
	151	+ for (i = 0; i < font->height; i++)
	152	+ early_efi_clear_scanline(efi_y + i);
	153	+ }
	154	+ }
	155	+}
	156	+
	157	+static __init int early_efi_setup(struct console con, char options)
	158	+{
	159	+ struct screen_info *si;
	160	+ u16 xres, yres;
	161	+ u32 i;
	162	+
	163	+ si = &boot_params.screen_info;
	164	+ xres = si->lfb_width;
	165	+ yres = si->lfb_height;
	166	+
	167	+ /*
	168	+ * early_efi_write_char() implicitly assumes a framebuffer with
	169	+ * 32-bits per pixel.
	170	+ */
	171	+ if (si->lfb_depth != 32)
	172	+ return -ENODEV;
	173	+
	174	+ font = get_default_font(xres, yres, -1, -1);
	175	+ if (!font)
	176	+ return -ENODEV;
	177	+
	178	+ efi_y = rounddown(yres, font->height) - font->height;
	179	+ for (i = 0; i < (yres - efi_y) / font->height; i++)
	180	+ early_efi_scroll_up();
	181	+
	182	+ return 0;
	183	+}
	184	+
	185	+struct console early_efi_console = {
	186	+ .name = "earlyefi",
	187	+ .write = early_efi_write,
	188	+ .setup = early_efi_setup,
	189	+ .flags = CON_PRINTBUFFER,
	190	+ .index = -1,
	191	+};