[PATCH v3 0/2] efi: arm: add support for earlycon on EFI framebuffer

[PATCH v3 0/2] efi: arm: add support for earlycon on EFI framebuffer

[Ard Biesheuvel]

Repurpose the existing EFI earlyprintk code to implement support for
'earlycon=efi' for arm64 systems, allowing the graphical console
to be used instead of the serial port for early debug output.

Changes since v2:
- update patch #1 so that no attempts are made to build the memencrypt related
  early memremap routines for 32-bit x86
- update patch #2 so earlycon=efifb is not enabled on Itanium

Changes since v1:
- Rename earlycon= argument to 'efifb' to emphasize that this is specific
  to the EFI framebuffer.
- Replace earlyprintk=efi entirely, rather than keep it alongside earlycon.
  Since earlycon is typically enabled (along with the infrastructure), and
  earlyprintk isn't, this does not result in a lot more code to be included,
  but does make it more likely that a given [distro] kernel has support for
  this enabled out of the box.
- Switch to write-combine mappings by default. This is the default for efifb,
  and is actually required on arm64, since device attributes do not tolerate
  unaligned accesses or other operations (such as DC ZVA) that rely on memory
  semantics. This requires ARCH_USE_MEMREMAP_PROT to be wired up, which is
  why a new patch #1 has been added.
- Since adding the 'ram' parameter for framebuffers in shared memory on cache
  coherent devices is trivial after the switch to WC mappings, fold the change
  into the main patch.

If there are no objections, I will proceed to queue these in efi/next for v5.1

Cc: corbet@lwn.net
Cc: leif.lindholm@linaro.org
Cc: graeme.gregory@linaro.org
Cc: mingo@redhat.com
Cc: tglx@linutronix.de
Cc: linux-doc@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: agraf@suse.de
Cc: pjones@redhat.com

Ard Biesheuvel (2):
  x86: make ARCH_USE_MEMREMAP_PROT a generic Kconfig symbol
  efi: x86: convert x86 EFI earlyprintk into generic earlycon
    implementation

 Documentation/admin-guide/kernel-parameters.txt                         |   8 +-
 arch/Kconfig                                                            |   3 +
 arch/x86/Kconfig                                                        |   5 +-
 arch/x86/Kconfig.debug                                                  |  10 --
 arch/x86/include/asm/efi.h                                              |   1 -
 arch/x86/kernel/early_printk.c                                          |   4 -
 arch/x86/mm/ioremap.c                                                   |   4 +-
 arch/x86/platform/efi/Makefile                                          |   1 -
 drivers/firmware/efi/Kconfig                                            |   6 +
 drivers/firmware/efi/Makefile                                           |   1 +
 arch/x86/platform/efi/early_printk.c => drivers/firmware/efi/earlycon.c | 130 ++++++++------------
 11 files changed, 69 insertions(+), 104 deletions(-)
 rename arch/x86/platform/efi/early_printk.c => drivers/firmware/efi/earlycon.c (45%)

-- 
2.20.1


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[PATCH v3 1/2] x86: make ARCH_USE_MEMREMAP_PROT a generic Kconfig symbol

[Ard Biesheuvel]

Turn ARCH_USE_MEMREMAP_PROT into a generic Kconfig symbol, and fix the
dependency expression to reflect that AMD_MEM_ENCRYPT depends on it,
instead of the other way around. This will permit ARCH_USE_MEMREMAP_PROT
to be selected by other architectures and other subsystems, such as
earlycon for efifb in a subsequent patch.

Note that this will cause the encryption related early memremap routines
in arch/x86/mm/ioremap.c to be built for 32-bit x86 as well, which triggers
the following warning:

     arch/x86//mm/ioremap.c: In function 'early_memremap_encrypted':
  >> arch/x86/include/asm/pgtable_types.h:193:27: warning: conversion from
                     'long long unsigned int' to 'long unsigned int' changes
                     value from '9223372036854776163' to '355' [-Woverflow]
      #define __PAGE_KERNEL_ENC (__PAGE_KERNEL | _PAGE_ENC)
                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~
     arch/x86//mm/ioremap.c:713:46: note: in expansion of macro '__PAGE_KERNEL_ENC'
       return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_ENC);

which essentially means they are 64-bit only anyway. However, we cannot
make them dependent on CONFIG_ARCH_HAS_MEM_ENCRYPT, since that is always
defined, even for i386 (and changing that results in a slew of build errors)

So instead, build those routines only if CONFIG_AMD_MEM_ENCRYPT is
defined.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 arch/Kconfig          | 3 +++
 arch/x86/Kconfig      | 5 +----
 arch/x86/mm/ioremap.c | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 4cfb6de48f79..9f0213213da8 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -885,6 +885,9 @@ config HAVE_ARCH_PREL32_RELOCATIONS
 	  architectures, and don't require runtime relocation on relocatable
 	  kernels.
 
+config ARCH_USE_MEMREMAP_PROT
+	bool
+
 source "kernel/gcov/Kconfig"
 
 source "scripts/gcc-plugins/Kconfig"
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 15af091611e2..09c2c5600579 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1510,6 +1510,7 @@ config AMD_MEM_ENCRYPT
 	bool "AMD Secure Memory Encryption (SME) support"
 	depends on X86_64 && CPU_SUP_AMD
 	select DYNAMIC_PHYSICAL_MASK
+	select ARCH_USE_MEMREMAP_PROT
 	---help---
 	  Say yes to enable support for the encryption of system memory.
 	  This requires an AMD processor that supports Secure Memory
@@ -1529,10 +1530,6 @@ config AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT
 	  If set to N, then the encryption of system memory can be
 	  activated with the mem_encrypt=on command line option.
 
-config ARCH_USE_MEMREMAP_PROT
-	def_bool y
-	depends on AMD_MEM_ENCRYPT
-
 # Common NUMA Features
 config NUMA
 	bool "Numa Memory Allocation and Scheduler Support"
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 5378d10f1d31..0029604af8a4 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -705,7 +705,7 @@ bool phys_mem_access_encrypted(unsigned long phys_addr, unsigned long size)
 	return arch_memremap_can_ram_remap(phys_addr, size, 0);
 }
 
-#ifdef CONFIG_ARCH_USE_MEMREMAP_PROT
+#ifdef CONFIG_AMD_MEM_ENCRYPT
 /* Remap memory with encryption */
 void __init *early_memremap_encrypted(resource_size_t phys_addr,
 				      unsigned long size)
@@ -747,7 +747,7 @@ void __init *early_memremap_decrypted_wp(resource_size_t phys_addr,
 
 	return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_NOENC_WP);
 }
-#endif	/* CONFIG_ARCH_USE_MEMREMAP_PROT */
+#endif	/* CONFIG_AMD_MEM_ENCRYPT */
 
 static pte_t bm_pte[PAGE_SIZE/sizeof(pte_t)] __page_aligned_bss;
 
-- 
2.20.1


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[PATCH v3 2/2] efi: x86: convert x86 EFI earlyprintk into generic earlycon implementation

[Ard Biesheuvel]

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, nor is its early_memremap operational
early enough, so it is disabled there. Itanium has its own
asm/early_ioremap.h header which does not declare early_memremap_prot
(and it never implemented earlyprintk=efi in the first place) so
let's just disable it there as well.

Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 Documentation/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 +
 arch/x86/platform/efi/early_printk.c => drivers/firmware/efi/earlycon.c | 130 ++++++++------------
 8 files changed, 63 insertions(+), 98 deletions(-)

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 45%
rename from arch/x86/platform/efi/early_printk.c
rename to drivers/firmware/efi/earlycon.c
index 7138bc7a265c..163d8204b190 100644
--- a/arch/x86/platform/efi/early_printk.c
+++ b/drivers/firmware/efi/earlycon.c
@@ -10,104 +10,68 @@
 #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 +92,14 @@ 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 +119,7 @@ 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 +128,12 @@ 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 +156,39 @@ 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 +200,9 @@ 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);
-- 
2.20.1


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