[PATCH 09/10] efi: x86: convert x86 EFI earlyprintk into generic earlycon implementation

Ard Biesheuvel
2019-02-02T09:41:56Z

Move the x86 EFI earlyprintk implementation to a shared location under
drivers/firmware and tweak it slightly so we can expose it as an earlycon
implementation (which is generic) rather than earlyprintk (which is only
implemented for a few architectures)

This also involves switching to write-combine mappings by default (which
is required on ARM since device mappings lack memory semantics, and so
memcpy/memset may not be used on them), and adding support for shared
memory framebuffers on cache coherent non-x86 systems (which do not
tolerate mismatched attributes)

Note that 32-bit ARM does not populate its struct screen_info early
enough for earlycon=efifb to work, so it is disabled there.

Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
.../admin-guide/kernel-parameters.txt | 8 +-
arch/x86/Kconfig.debug | 10 --
arch/x86/include/asm/efi.h | 1 -
arch/x86/kernel/early_printk.c | 4 -
arch/x86/platform/efi/Makefile | 1 -
drivers/firmware/efi/Kconfig | 6 +
drivers/firmware/efi/Makefile | 1 +
.../firmware/efi/earlycon.c | 134 +++++++-----------
8 files changed, 64 insertions(+), 101 deletions(-)
rename arch/x86/platform/efi/early_printk.c => drivers/firmware/efi/earlycon.c (42%)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b799bcf67d7b..76dd3baa31e0 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1073,9 +1073,15 @@
specified address. The serial port must already be
setup and configured. Options are not yet supported.

+ efifb,[options]
+ Start an early, unaccelerated console on the EFI
+ memory mapped framebuffer (if available). On cache
+ coherent non-x86 systems that use system memory for
+ the framebuffer, pass the 'ram' option so that it is
+ mapped with the correct attributes.
+
earlyprintk= [X86,SH,ARM,M68k,S390]
earlyprintk=vga
- earlyprintk=efi
earlyprintk=sclp
earlyprintk=xen
earlyprintk=serial[,ttySn[,baudrate]]
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 0723dff17e6c..15d0fbe27872 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -40,16 +40,6 @@ config EARLY_PRINTK_DBGP
with klogd/syslogd or the X server. You should normally say 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 EARLY_PRINTK_USB_XDBC
bool "Early printk via the xHCI debug port"
depends on EARLY_PRINTK && PCI
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index a37378f986ec..08ebb2270d87 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -170,7 +170,6 @@ static inline bool efi_runtime_supported(void)
return false;
}

-extern struct console early_efi_console;
extern void parse_efi_setup(u64 phys_addr, u32 data_len);

extern void efifb_setup_from_dmi(struct screen_info *si, const char *opt);
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 374a52fa5296..9b33904251a9 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -388,10 +388,6 @@ static int __init setup_early_printk(char *buf)
if (!strncmp(buf, "xen", 3))
early_console_register(&xenboot_console, keep);
#endif
-#ifdef CONFIG_EARLY_PRINTK_EFI
- if (!strncmp(buf, "efi", 3))
- early_console_register(&early_efi_console, keep);
-#endif
#ifdef CONFIG_EARLY_PRINTK_USB_XDBC
if (!strncmp(buf, "xdbc", 4))
early_xdbc_parse_parameter(buf + 4);
diff --git a/arch/x86/platform/efi/Makefile b/arch/x86/platform/efi/Makefile
index e4dc3862d423..fe29f3f5d384 100644
--- a/arch/x86/platform/efi/Makefile
+++ b/arch/x86/platform/efi/Makefile
@@ -3,5 +3,4 @@ OBJECT_FILES_NON_STANDARD_efi_thunk_$(BITS).o := y
OBJECT_FILES_NON_STANDARD_efi_stub_$(BITS).o := y

obj-$(CONFIG_EFI) += quirks.o efi.o efi_$(BITS).o efi_stub_$(BITS).o
-obj-$(CONFIG_EARLY_PRINTK_EFI) += early_printk.o
obj-$(CONFIG_EFI_MIXED) += efi_thunk_$(BITS).o
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 89110dfc7127..190be0b1d109 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -198,3 +198,9 @@ config EFI_DEV_PATH_PARSER
bool
depends on ACPI
default n
+
+config EFI_EARLYCON
+ def_bool y
+ depends on SERIAL_EARLYCON && !ARM && !IA64
+ select FONT_SUPPORT
+ select ARCH_USE_MEMREMAP_PROT
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 5f9f5039de50..d2d0d2030620 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -30,5 +30,6 @@ arm-obj-$(CONFIG_EFI) := arm-init.o arm-runtime.o
obj-$(CONFIG_ARM) += $(arm-obj-y)
obj-$(CONFIG_ARM64) += $(arm-obj-y)
obj-$(CONFIG_EFI_CAPSULE_LOADER) += capsule-loader.o
+obj-$(CONFIG_EFI_EARLYCON) += earlycon.o
obj-$(CONFIG_UEFI_CPER_ARM) += cper-arm.o
obj-$(CONFIG_UEFI_CPER_X86) += cper-x86.o
diff --git a/arch/x86/platform/efi/early_printk.c b/drivers/firmware/efi/earlycon.c
similarity index 42%
rename from arch/x86/platform/efi/early_printk.c
rename to drivers/firmware/efi/earlycon.c
index 7138bc7a265c..dc1ae14ea4cf 100644
--- a/arch/x86/platform/efi/early_printk.c
+++ b/drivers/firmware/efi/earlycon.c
@@ -1,8 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
/*
* 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>
@@ -10,104 +8,68 @@
#include <linux/font.h>
#include <linux/io.h>
#include <linux/kernel.h>
-#include <asm/setup.h>
+#include <linux/serial_core.h>
+#include <linux/screen_info.h>
+
+#include <asm/early_ioremap.h>

static const struct font_desc *font;
static u32 efi_x, efi_y;
-static void *efi_fb;
-static bool early_efi_keep;
-
-/*
- * efi earlyprintk need use early_ioremap to map the framebuffer.
- * But early_ioremap is not usable for earlyprintk=efi,keep, ioremap should
- * be used instead. ioremap will be available after paging_init() which is
- * earlier than initcall callbacks. Thus adding this early initcall function
- * early_efi_map_fb to map the whole efi framebuffer.
- */
-static __init int early_efi_map_fb(void)
-{
- u64 base, size;
+static u64 fb_base;
+static pgprot_t fb_prot;

- if (!early_efi_keep)
- return 0;
-
- base = boot_params.screen_info.lfb_base;
- if (boot_params.screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
- base |= (u64)boot_params.screen_info.ext_lfb_base << 32;
- size = boot_params.screen_info.lfb_size;
- efi_fb = ioremap(base, size);
-
- return efi_fb ? 0 : -ENOMEM;
-}
-early_initcall(early_efi_map_fb);
-
-/*
- * early_efi_map maps efi framebuffer region [start, start + len -1]
- * In case earlyprintk=efi,keep we have the whole framebuffer mapped already
- * so just return the offset efi_fb + start.
- */
-static __ref void *early_efi_map(unsigned long start, unsigned long len)
+static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
{
- u64 base;
-
- base = boot_params.screen_info.lfb_base;
- if (boot_params.screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
- base |= (u64)boot_params.screen_info.ext_lfb_base << 32;
-
- if (efi_fb)
- return (efi_fb + start);
- else
- return early_ioremap(base + start, len);
+ return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
}

-static __ref void early_efi_unmap(void *addr, unsigned long len)
+static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
{
- if (!efi_fb)
- early_iounmap(addr, len);
+ early_memunmap(addr, len);
}

-static void early_efi_clear_scanline(unsigned int y)
+static void efi_earlycon_clear_scanline(unsigned int y)
{
unsigned long *dst;
u16 len;

- len = boot_params.screen_info.lfb_linelength;
- dst = early_efi_map(y*len, len);
+ len = screen_info.lfb_linelength;
+ dst = efi_earlycon_map(y*len, len);
if (!dst)
return;

memset(dst, 0, len);
- early_efi_unmap(dst, len);
+ efi_earlycon_unmap(dst, len);
}

-static void early_efi_scroll_up(void)
+static void efi_earlycon_scroll_up(void)
{
unsigned long *dst, *src;
u16 len;
u32 i, height;

- len = boot_params.screen_info.lfb_linelength;
- height = boot_params.screen_info.lfb_height;
+ len = screen_info.lfb_linelength;
+ height = screen_info.lfb_height;

for (i = 0; i < height - font->height; i++) {
- dst = early_efi_map(i*len, len);
+ dst = efi_earlycon_map(i*len, len);
if (!dst)
return;

- src = early_efi_map((i + font->height) * len, len);
+ src = efi_earlycon_map((i + font->height) * len, len);
if (!src) {
- early_efi_unmap(dst, len);
+ efi_earlycon_unmap(dst, len);
return;
}

memmove(dst, src, len);

- early_efi_unmap(src, len);
- early_efi_unmap(dst, len);
+ efi_earlycon_unmap(src, len);
+ efi_earlycon_unmap(dst, len);
}
}

-static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
+static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
{
const u32 color_black = 0x00000000;
const u32 color_white = 0x00ffffff;
@@ -128,14 +90,14 @@ static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
}

static void
-early_efi_write(struct console *con, const char *str, unsigned int num)
+efi_earlycon_write(struct console *con, const char *str, unsigned int num)
{
struct screen_info *si;
unsigned int len;
const char *s;
void *dst;

- si = &boot_params.screen_info;
+ si = &screen_info;
len = si->lfb_linelength;

while (num) {
@@ -155,7 +117,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
for (h = 0; h < font->height; h++) {
unsigned int n, x;

- dst = early_efi_map((efi_y + h) * len, len);
+ dst = efi_earlycon_map((efi_y + h) * len, len);
if (!dst)
return;

@@ -164,12 +126,12 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
x = efi_x;

while (n-- > 0) {
- early_efi_write_char(dst + x*4, *s, h);
+ efi_earlycon_write_char(dst + x*4, *s, h);
x += font->width;
s++;
}

- early_efi_unmap(dst, len);
+ efi_earlycon_unmap(dst, len);
}

num -= count;
@@ -192,26 +154,39 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
u32 i;

efi_y -= font->height;
- early_efi_scroll_up();
+ efi_earlycon_scroll_up();

for (i = 0; i < font->height; i++)
- early_efi_clear_scanline(efi_y + i);
+ efi_earlycon_clear_scanline(efi_y + i);
}
}
}

-static __init int early_efi_setup(struct console *con, char *options)
+static int __init efi_earlycon_setup(struct earlycon_device *device,
+ const char *opt)
{
struct screen_info *si;
u16 xres, yres;
u32 i;

- si = &boot_params.screen_info;
+ if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
+ return -ENODEV;
+
+ fb_base = screen_info.lfb_base;
+ if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
+ fb_base |= (u64)screen_info.ext_lfb_base << 32;
+
+ if (opt && !strcmp(opt, "ram"))
+ fb_prot = PAGE_KERNEL;
+ else
+ fb_prot = pgprot_writecombine(PAGE_KERNEL);
+
+ si = &screen_info;
xres = si->lfb_width;
yres = si->lfb_height;

/*
- * early_efi_write_char() implicitly assumes a framebuffer with
+ * efi_earlycon_write_char() implicitly assumes a framebuffer with
* 32-bits per pixel.
*/
if (si->lfb_depth != 32)
@@ -223,18 +198,9 @@ static __init int early_efi_setup(struct console *con, char *options)

efi_y = rounddown(yres, font->height) - font->height;
for (i = 0; i < (yres - efi_y) / font->height; i++)
- early_efi_scroll_up();
+ efi_earlycon_scroll_up();

- /* early_console_register will unset CON_BOOT in case ,keep */
- if (!(con->flags & CON_BOOT))
- early_efi_keep = true;
+ device->con->write = efi_earlycon_write;
return 0;
}
-
-struct console early_efi_console = {
- .name = "earlyefi",
- .write = early_efi_write,
- .setup = early_efi_setup,
- .flags = CON_PRINTBUFFER,
- .index = -1,
-};
+EARLYCON_DECLARE(efifb, efi_earlycon_setup);
--
2.17.1