Re: [PATCH v5 10/10] x86, efi: EFI boot stub support

[Maarten Lankhorst]

Hey Matt,

On 10/17/2011 12:40 PM, Matt Fleming wrote:
> From: Matt Fleming <matt.fleming@xxxxxxxxx>
>
> There is currently a large divide between kernel development and the
> development of EFI boot loaders. The idea behind this patch is to give
> the kernel developers full control over the EFI boot process. As
> H. Peter Anvin put it,
>
> "The 'kernel carries its own stub' approach been very successful in
> dealing with BIOS, and would make a lot of sense to me for EFI as
> well."
>
> This patch introduces an EFI boot stub that allows an x86 bzImage to
> be loaded and executed by EFI firmware. The bzImage appears to the
> firmware as an EFI application. Luckily there are enough free bits
> within the bzImage header so that it can masquerade as an EFI
> application, thereby coercing the EFI firmware into loading it and
> jumping to its entry point. The beauty of this masquerading approach
> is that both BIOS and EFI boot loaders can still load and run the same
> bzImage, thereby allowing a single kernel image to work in any boot
> environment.
>
> The EFI boot stub supports multiple initrds, but they must exist on
> the same partition as the bzImage. Command-line arguments for the
> kernel can be appended after the bzImage name when run from the EFI
> shell, e.g.
>
> Shell> bzImage console=ttyS0 root=/dev/sdb initrd=initrd.img
>
> Cc: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxx>
> Cc: Mike Waychison <mikew@xxxxxxxxxx>
> Cc: Matthew Garrett <mjg@xxxxxxxxxx>
> Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <m.b.lankhorst@xxxxxxxxx>
> Tested-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
> Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
> ---
>
> v5:
>
>  - load_options_size is UTF-16, which needs dividing by 2 to convert
>    to the corresponding ASCII size (spotted by Maarten).
>
> v4:
>
>  - Don't read more than image->load_options_size
>
> v3:
>
>  - Fix following warnings when compiling CONFIG_EFI_STUB=n
>
>    arch/x86/boot/tools/build.c: In function âmainâ:
>    arch/x86/boot/tools/build.c:138:24: warning: unused variable âpe_headerâ
>    arch/x86/boot/tools/build.c:138:15: warning: unused variable âfile_szâ
>
>  - As reported by Matthew Garrett, some Apple machines have GOPs that
>    don't have hardware attached. We need to weed these out by
>    searching for ones that handle the PCIIO protocol.
>
>  - Don't allocate memory if no initrds are on cmdline
>  - Don't trust image->load_options_size
>
> Maarten Lankhorst noted:
>  - Don't strip first argument when booted from efibootmgr
>  - Don't allocate too much memory for cmdline
>  - Don't update cmdline_size, the kernel considers it read-only
>  - Don't accept '\n' for initrd names
>
> v2:
>
>  - File alignment was too large, was 8192 should be 512. Reported by
>    Maarten Lankhorst on LKML.
>  - Added UGA support for graphics
>  - Use VIDEO_TYPE_EFI instead of hard-coded number.
>  - Move linelength assignment until after we've assigned depth
>  - Dynamically fill out AddressOfEntryPoint in tools/build.c
>  - Don't use magic number for GDT/TSS stuff. Requested by Andi Kleen
>  - The bzImage may need to be relocated as it may have been loaded at
>    a high address address by the firmware. This was required to get my
>    macbook booting because the firmware loaded it at 0x7cxxxxxx, which
>    triggers this error in decompress_kernel(),
>
> 	if (heap > ((-__PAGE_OFFSET-(128<<20)-1) & 0x7fffffff))
> 		error("Destination address too large");
>
>  arch/x86/Kconfig                       |    7 +
>  arch/x86/boot/compressed/Makefile      |   10 +-
>  arch/x86/boot/compressed/eboot.c       |  975 ++++++++++++++++++++++++++++++++
>  arch/x86/boot/compressed/efi_stub_32.S |   87 +++
>  arch/x86/boot/compressed/efi_stub_64.S |    1 +
>  arch/x86/boot/compressed/head_32.S     |   22 +
>  arch/x86/boot/compressed/head_64.S     |   20 +
>  arch/x86/boot/compressed/string.c      |    9 +
>  arch/x86/boot/header.S                 |  158 +++++
>  arch/x86/boot/string.c                 |   35 ++
>  arch/x86/boot/tools/build.c            |   39 ++
>  arch/x86/kernel/asm-offsets.c          |    2 +
>  12 files changed, 1364 insertions(+), 1 deletions(-)
>  create mode 100644 arch/x86/boot/compressed/eboot.c
>  create mode 100644 arch/x86/boot/compressed/efi_stub_32.S
>  create mode 100644 arch/x86/boot/compressed/efi_stub_64.S
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 6a47bb2..d40c876 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1466,6 +1466,13 @@ config EFI
>  	  resultant kernel should continue to boot on existing non-EFI
>  	  platforms.
>  
> +config EFI_STUB
> +       bool "EFI stub support"
> +       depends on EFI
> +       ---help---
> +          This kernel feature allows a bzImage to be loaded directly
> +	  by EFI firmware without the use of a bootloader.
> +
>  config SECCOMP
>  	def_bool y
>  	prompt "Enable seccomp to safely compute untrusted bytecode"
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index 09664ef..b123b9a 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -23,7 +23,15 @@ LDFLAGS_vmlinux := -T
>  
>  hostprogs-y	:= mkpiggy
>  
> -$(obj)/vmlinux: $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o $(obj)/string.o $(obj)/cmdline.o $(obj)/early_serial_console.o $(obj)/piggy.o FORCE
> +VMLINUX_OBJS = $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o \
> +	$(obj)/string.o $(obj)/cmdline.o $(obj)/early_serial_console.o \
> +	$(obj)/piggy.o
> +
> +ifeq ($(CONFIG_EFI_STUB), y)
> +	VMLINUX_OBJS += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o
> +endif
> +
> +$(obj)/vmlinux: $(VMLINUX_OBJS) FORCE
>  	$(call if_changed,ld)
>  	@:
>  
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> new file mode 100644
> index 0000000..f84e389
> --- /dev/null
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -0,0 +1,975 @@
> +/* -----------------------------------------------------------------------
> + *
> + *   Copyright 2011 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/efi.h>
> +#include <asm/efi.h>
> +#include <asm/setup.h>
> +#include <asm/desc.h>
> +
> +#define SEG_TYPE_DATA		(0 << 3)
> +#define SEG_TYPE_READ_WRITE	(1 << 1)
> +#define SEG_TYPE_CODE		(1 << 3)
> +#define SEG_TYPE_EXEC_READ	(1 << 1)
> +#define SEG_TYPE_TSS		((1 << 3) | (1 << 0))
> +#define SEG_OP_SIZE_32BIT	(1 << 0)
> +#define SEG_GRANULARITY_4KB	(1 << 0)
> +
> +#define DESC_TYPE_CODE_DATA	(1 << 0)
> +
> +#define EFI_PAGE_SIZE		(1UL << EFI_PAGE_SHIFT)
> +
> +#define PIXEL_RGB_RESERVED_8BIT_PER_COLOR		0
> +#define PIXEL_BGR_RESERVED_8BIT_PER_COLOR		1
> +#define PIXEL_BIT_MASK					2
> +#define PIXEL_BLT_ONLY					3
> +#define PIXEL_FORMAT_MAX				4
> +
> +typedef struct {
> +	u32 red_mask;
> +	u32 green_mask;
> +	u32 blue_mask;
> +	u32 reserved_mask;
> +} efi_pixel_bitmask_t;
> +
> +typedef struct {
> +	u32 version;
> +	u32 horizontal_resolution;
> +	u32 vertical_resolution;
> +	int pixel_format;
> +	efi_pixel_bitmask_t pixel_information;
> +	u32 pixels_per_scan_line;
> +} __attribute__((packed)) efi_graphics_output_mode_information_t;
> +
> +typedef struct {
> +	u32 max_mode;
> +	u32 mode;
> +	unsigned long info;
> +	unsigned long size_of_info;
> +	u64 frame_buffer_base;
> +	unsigned long frame_buffer_size;
> +} __attribute__((packed)) efi_graphics_output_protocol_mode_t;
> +
> +typedef struct {
> +	void *query_mode;
> +	unsigned long set_mode;
> +	unsigned long blt;
> +	efi_graphics_output_protocol_mode_t *mode;
> +} efi_graphics_output_protocol_t;
> +
> +typedef struct {
> +	void *get_mode;
> +	void *set_mode;
> +	void *blt;
> +} efi_uga_draw_protocol_t;
> +
> +static efi_system_table_t *sys_table;
> +
> +static efi_status_t low_alloc(unsigned long size, unsigned long align,
> +			      unsigned long *addr)
> +{
> +	unsigned long map_size, key, desc_size;
> +	efi_memory_desc_t *map;
> +	efi_status_t status;
> +	unsigned long nr_pages;
> +	u32 desc_version;
> +	int i;
> +
> +	nr_pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
> +
> +	map_size = sizeof(*map) * 32;
> +
> +again:
> +	/*
> +	 * Add an additional efi_memory_desc_t because we're doing an
> +	 * allocation which may be in a new descriptor region.
> +	 */
> +	map_size += sizeof(*map);
> +	status = efi_call_phys3(sys_table->boottime->allocate_pool,
> +				EFI_LOADER_DATA, map_size, (void **)&map);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	status = efi_call_phys5(sys_table->boottime->get_memory_map, &map_size,
> +				map, &key, &desc_size, &desc_version);
> +	if (status == EFI_BUFFER_TOO_SMALL) {
> +		efi_call_phys1(sys_table->boottime->free_pool, map);
> +		goto again;
> +	}
> +
> +	if (status != EFI_SUCCESS)
> +		goto free_pool;
> +
> +	for (i = 0; i < map_size / desc_size; i++) {
> +		efi_memory_desc_t *desc;
> +		u64 start, end;
> +
> +		desc = (efi_memory_desc_t *)((unsigned long)map + (i * desc_size));
> +
> +		if (desc->type != EFI_CONVENTIONAL_MEMORY)
> +			continue;
> +
> +		if (desc->num_pages < nr_pages)
> +			continue;
> +
> +		start = desc->phys_addr;
> +		end = start + desc->num_pages * (1UL << EFI_PAGE_SHIFT);
> +
> +		/*
> +		 * Don't allocate at 0x0. It will confuse code that
> +		 * checks pointers against NULL. Skip the first 8
> +		 * bytes so we start at a nice even number.
> +		 */
> +		if (start == 0x0) {
> +			start += 8;
> +
> +			/* Check for tiny memory regions */
> +			if (start >= end)
> +				continue;
> +		}
> +
> +		start = round_up(start, align);
> +		if ((start + size) > end)
> +			continue;
> +
> +		status = efi_call_phys4(sys_table->boottime->allocate_pages,
> +					EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA,
> +					nr_pages, &start);
> +		if (status == EFI_SUCCESS) {
> +			*addr = start;
> +			break;
> +		}
> +	}
> +
> +	if (i == map_size / desc_size)
> +		status = EFI_NOT_FOUND;
> +
> +free_pool:
> +	efi_call_phys1(sys_table->boottime->free_pool, map);
> +fail:
> +	return status;
> +}
> +
> +static void low_free(unsigned long size, unsigned long addr)
> +{
> +	unsigned long nr_pages;
> +
> +	nr_pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
> +	efi_call_phys2(sys_table->boottime->free_pages, addr, size);
> +}
> +
> +static void find_bits(unsigned long mask, u8 *pos, u8 *size)
> +{
> +        u8 first, len;
> +
> +	first = 0;
> +	len = 0;
> +
> +	if (mask) {
> +		while (!(mask & 0x1)) {
> +			mask = mask >> 1;
> +			first++;
> +		}
> +
> +		while (mask & 0x1) {
> +			mask = mask >> 1;
> +			len++;
> +		}
> +	}
> +
> +        *pos = first;
> +        *size = len;
> +}
> +
> +/*
> + * See if we have Graphics Output Protocol
> + */
> +static efi_status_t setup_gop(struct screen_info *si, efi_guid_t *proto,
> +			      unsigned long size)
> +{
> +	efi_graphics_output_protocol_t *gop, *first_gop;
> +	efi_pixel_bitmask_t pixel_info;
> +	unsigned long nr_gops;
> +	efi_status_t status;
> +	void **gop_handle;
> +	u16 width, height;
> +	u32 fb_base, fb_size;
> +	u32 pixels_per_scan_line;
> +	int pixel_format;
> +	int i;
> +
> +	status = efi_call_phys3(sys_table->boottime->allocate_pool,
> +				EFI_LOADER_DATA, size, &gop_handle);
> +	if (status != EFI_SUCCESS)
> +		return status;
> +
> +	status = efi_call_phys5(sys_table->boottime->locate_handle,
> +				EFI_LOCATE_BY_PROTOCOL, proto,
> +				NULL, &size, gop_handle);
> +	if (status != EFI_SUCCESS)
> +		goto free_handle;
> +
> +	first_gop = NULL;
> +
> +	nr_gops = size / sizeof(void *);
> +	for (i = 0; i < nr_gops; i++) {
> +		efi_graphics_output_mode_information_t *info;
> +		efi_guid_t pciio_proto = EFI_PCI_IO_PROTOCOL_GUID;
> +		void *pciio;
> +		void *h = gop_handle[i];
> +
> +		status = efi_call_phys3(sys_table->boottime->handle_protocol,
> +					h, proto, &gop);
> +		if (status != EFI_SUCCESS)
> +			continue;
> +
> +		efi_call_phys3(sys_table->boottime->handle_protocol,
> +			       h, &pciio_proto, &pciio);
> +
> +		status = efi_call_phys4(gop->query_mode, gop,
> +					gop->mode->mode, &size, &info);
> +		if (status == EFI_SUCCESS && (!first_gop || pciio)) {
> +			/*
> +			 * Apple provide GOPs that are not backed by
> +			 * real hardware (they're used to handle
> +			 * multiple displays). The workaround is to
> +			 * search for a GOP implementing the PCIIO
> +			 * protocol, and if one isn't found, to just
> +			 * fallback to the first GOP.
> +			 */
> +			width = info->horizontal_resolution;
> +			height = info->vertical_resolution;
> +			fb_base = gop->mode->frame_buffer_base;
> +			fb_size = gop->mode->frame_buffer_size;
> +			pixel_format = info->pixel_format;
> +			pixel_info = info->pixel_information;
> +			pixels_per_scan_line = info->pixels_per_scan_line;
> +
> +			/*
> +			 * Once we've found a GOP supporting PCIIO,
> +			 * don't bother looking any further.
> +			 */
> +			if (pciio)
> +				break;
> +
> +			first_gop = gop;
> +		}
> +	}
> +
> +	/* Did we find any GOPs? */
> +	if (!first_gop)
> +		goto free_handle;
> +
> +	/* EFI framebuffer */
> +	si->orig_video_isVGA = VIDEO_TYPE_EFI;
> +
> +	si->lfb_width = width;
> +	si->lfb_height = height;
> +	si->lfb_base = fb_base;
> +	si->lfb_size = fb_size;
> +	si->pages = 1;
> +
> +	if (pixel_format == PIXEL_RGB_RESERVED_8BIT_PER_COLOR) {
> +		si->lfb_depth = 32;
> +		si->lfb_linelength = pixels_per_scan_line * 4;
> +		si->red_size = 8;
> +		si->red_pos = 0;
> +		si->green_size = 8;
> +		si->green_pos = 8;
> +		si->blue_size = 8;
> +		si->blue_pos = 16;
> +		si->rsvd_size = 8;
> +		si->rsvd_pos = 24;
> +	} else if (pixel_format == PIXEL_BGR_RESERVED_8BIT_PER_COLOR) {
> +		si->lfb_depth = 32;
> +		si->lfb_linelength = pixels_per_scan_line * 4;
> +		si->red_size = 8;
> +		si->red_pos = 16;
> +		si->green_size = 8;
> +		si->green_pos = 8;
> +		si->blue_size = 8;
> +		si->blue_pos = 0;
> +		si->rsvd_size = 8;
> +		si->rsvd_pos = 24;
> +	} else if (pixel_format == PIXEL_BIT_MASK) {
> +		find_bits(pixel_info.red_mask, &si->red_pos, &si->red_size);
> +		find_bits(pixel_info.green_mask, &si->green_pos,
> +			  &si->green_size);
> +		find_bits(pixel_info.blue_mask, &si->blue_pos, &si->blue_size);
> +		find_bits(pixel_info.reserved_mask, &si->rsvd_pos,
> +			  &si->rsvd_size);
> +		si->lfb_depth = si->red_size + si->green_size +
> +			si->blue_size + si->rsvd_size;
> +		si->lfb_linelength = (pixels_per_scan_line * si->lfb_depth) / 8;
> +	} else {
> +		si->lfb_depth = 4;
> +		si->lfb_linelength = si->lfb_width / 2;
> +		si->red_size = 0;
> +		si->red_pos = 0;
> +		si->green_size = 0;
> +		si->green_pos = 0;
> +		si->blue_size = 0;
> +		si->blue_pos = 0;
> +		si->rsvd_size = 0;
> +		si->rsvd_pos = 0;
> +	}
> +
> +free_handle:
> +	efi_call_phys1(sys_table->boottime->free_pool, gop_handle);
> +	return status;
> +}
> +
> +/*
> + * See if we have Universal Graphics Adapter (UGA) protocol
> + */
> +static efi_status_t setup_uga(struct screen_info *si, efi_guid_t *uga_proto,
> +			      unsigned long size)
> +{
> +	efi_uga_draw_protocol_t *uga, *first_uga;
> +	unsigned long nr_ugas;
> +	efi_status_t status;
> +	u32 width, height;
> +	void **uga_handle = NULL;
> +	int i;
> +
> +	status = efi_call_phys3(sys_table->boottime->allocate_pool,
> +				EFI_LOADER_DATA, size, &uga_handle);
> +	if (status != EFI_SUCCESS)
> +		return status;
> +
> +	status = efi_call_phys5(sys_table->boottime->locate_handle,
> +				EFI_LOCATE_BY_PROTOCOL, uga_proto,
> +				NULL, &size, uga_handle);
> +	if (status != EFI_SUCCESS)
> +		goto free_handle;
> +
> +	first_uga = NULL;
> +
> +	nr_ugas = size / sizeof(void *);
> +	for (i = 0; i < nr_ugas; i++) {
> +		efi_guid_t pciio_proto = EFI_PCI_IO_PROTOCOL_GUID;
> +		void *handle = uga_handle[i];
> +		u32 w, h, depth, refresh;
> +		void *pciio;
> +
> +		status = efi_call_phys3(sys_table->boottime->handle_protocol,
> +					handle, uga_proto, &uga);
> +		if (status != EFI_SUCCESS)
> +			continue;
> +
> +		efi_call_phys3(sys_table->boottime->handle_protocol,
> +			       handle, &pciio_proto, &pciio);
> +
> +		status = efi_call_phys5(uga->get_mode, uga, &w, &h,
> +					&depth, &refresh);
> +		if (status == EFI_SUCCESS && (!first_uga || pciio)) {
> +			width = w;
> +			height = h;
> +
> +			/*
> +			 * Once we've found a UGA supporting PCIIO,
> +			 * don't bother looking any further.
> +			 */
> +			if (pciio)
> +				break;
> +
> +			first_uga = uga;
> +		}
> +	}
> +
> +	if (!first_uga)
> +		goto free_handle;
> +
> +	/* EFI framebuffer */
> +	si->orig_video_isVGA = VIDEO_TYPE_EFI;
> +
> +	si->lfb_depth = 32;
> +	si->lfb_width = width;
> +	si->lfb_height = height;
> +
> +	si->red_size = 8;
> +	si->red_pos = 16;
> +	si->green_size = 8;
> +	si->green_pos = 8;
> +	si->blue_size = 8;
> +	si->blue_pos = 0;
> +	si->rsvd_size = 8;
> +	si->rsvd_pos = 24;
> +
> +
> +free_handle:
> +	efi_call_phys1(sys_table->boottime->free_pool, uga_handle);
> +	return status;
> +}
> +
> +void setup_graphics(struct boot_params *boot_params)
> +{
> +	efi_guid_t graphics_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
> +	struct screen_info *si;
> +	efi_guid_t uga_proto = EFI_UGA_PROTOCOL_GUID;
> +	efi_status_t status;
> +	unsigned long size;
> +	void **gop_handle = NULL;
> +	void **uga_handle = NULL;
> +
> +	si = &boot_params->screen_info;
> +	memset(si, 0, sizeof(*si));
> +
> +	size = 0;
> +	status = efi_call_phys5(sys_table->boottime->locate_handle,
> +				EFI_LOCATE_BY_PROTOCOL, &graphics_proto,
> +				NULL, &size, gop_handle);
> +	if (status == EFI_BUFFER_TOO_SMALL)
> +		status = setup_gop(si, &graphics_proto, size);
> +
> +	if (status != EFI_SUCCESS) {
> +		size = 0;
> +		status = efi_call_phys5(sys_table->boottime->locate_handle,
> +					EFI_LOCATE_BY_PROTOCOL, &uga_proto,
> +					NULL, &size, uga_handle);
> +		if (status == EFI_BUFFER_TOO_SMALL)
> +			setup_uga(si, &uga_proto, size);
> +	}
> +}
> +
> +struct initrd {
> +	efi_file_handle_t *handle;
> +	u64 size;
> +};
> +
> +/*
> + * Check the cmdline for a LILO-style initrd= arguments.
> + *
> + * We only support loading an initrd from the same filesystem as the
> + * kernel image.
> + */
> +static efi_status_t handle_ramdisks(efi_loaded_image_t *image,
> +				    struct setup_header *hdr)
> +{
> +	struct initrd *initrds;
> +	unsigned long initrd_addr;
> +	efi_guid_t fs_proto = EFI_FILE_SYSTEM_GUID;
> +	u64 initrd_total;
> +	efi_file_io_interface_t *io;
> +	efi_file_handle_t *fh;
> +	efi_status_t status;
> +	int nr_initrds;
> +	char *str;
> +	int i, j, k;
> +
> +	initrd_addr = 0;
> +	initrd_total = 0;
> +
> +	str = (char *)(unsigned long)hdr->cmd_line_ptr;
> +
> +	j = 0;			/* See close_handles */
> +
> +	if (!str || !*str)
> +		return EFI_SUCCESS;
> +
> +	for (nr_initrds = 0; *str; nr_initrds++) {
> +		str = strstr(str, "initrd=");
> +		if (!str)
> +			break;
> +
> +		str += 7;
> +
> +		/* Skip any leading slashes */
> +		while (*str == '/' || *str == '\\')
> +			str++;
> +
> +		while (*str && *str != ' ' && *str != '\n')
> +			str++;
> +	}
> +
> +	if (!nr_initrds)
> +		return EFI_SUCCESS;
> +
> +	status = efi_call_phys3(sys_table->boottime->allocate_pool,
> +				EFI_LOADER_DATA,
> +				nr_initrds * sizeof(*initrds),
> +				&initrds);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	str = (char *)(unsigned long)hdr->cmd_line_ptr;
> +	for (i = 0; i < nr_initrds; i++) {
> +		struct initrd *initrd;
> +		efi_file_handle_t *h;
> +		efi_file_info_t *info;
> +		efi_char16_t filename[256];
> +		unsigned long info_sz;
> +		efi_guid_t info_guid = EFI_FILE_INFO_ID;
> +		efi_char16_t *p;
> +		u64 file_sz;
> +
> +		str = strstr(str, "initrd=");
> +		if (!str)
> +			break;
> +
> +		str += 7;
> +
> +		initrd = &initrds[i];
> +		p = filename;
> +
> +		/* Skip any leading slashes */
> +		while (*str == '/' || *str == '\\')
> +			str++;
> +
> +		while (*str && *str != ' ' && *str != '\n') {
> +			if (p >= filename + sizeof(filename))
> +				break;
> +
> +			*p++ = *str++;
> +		}
> +
> +		*p = '\0';
> +
> +		/* Only open the volume once. */
> +		if (!i) {
> +			efi_boot_services_t *boottime;
> +
> +			boottime = sys_table->boottime;
> +
> +			status = efi_call_phys3(boottime->handle_protocol,
> +					image->device_handle, &fs_proto, &io);
> +			if (status != EFI_SUCCESS)
> +				goto free_initrds;
> +
> +			status = efi_call_phys2(io->open_volume, io, &fh);
> +			if (status != EFI_SUCCESS)
> +				goto free_initrds;
> +		}
> +
> +		status = efi_call_phys5(fh->open, fh, &h, filename,
> +					EFI_FILE_MODE_READ, (u64)0);
> +		if (status != EFI_SUCCESS)
> +			goto close_handles;
> +
> +		initrd->handle = h;
> +
> +		info_sz = 0;
> +		status = efi_call_phys4(h->get_info, h, &info_guid,
> +					&info_sz, NULL);
> +		if (status != EFI_BUFFER_TOO_SMALL)
> +			goto close_handles;
> +
> +grow:
> +		status = efi_call_phys3(sys_table->boottime->allocate_pool,
> +					EFI_LOADER_DATA, info_sz, &info);
> +		if (status != EFI_SUCCESS)
> +			goto close_handles;
> +
> +		status = efi_call_phys4(h->get_info, h, &info_guid,
> +					&info_sz, info);
> +		if (status == EFI_BUFFER_TOO_SMALL) {
> +			efi_call_phys1(sys_table->boottime->free_pool, info);
> +			goto grow;
> +		}
> +
> +		file_sz = info->file_size;
> +		efi_call_phys1(sys_table->boottime->free_pool, info);
> +
> +		if (status != EFI_SUCCESS)
> +			goto close_handles;
> +
> +		initrd->size = file_sz;
> +		initrd_total += file_sz;
> +	}
> +
> +	if (initrd_total) {
> +		unsigned long addr;
> +
> +		/*
> +		 * Multiple initrd's need to be at consecutive
> +		 * addresses in memory, so allocate enough memory for
> +		 * all the initrd's.
> +		 */
> +		status = low_alloc(initrd_total, 0x1000, &initrd_addr);
> +		if (status != EFI_SUCCESS)
> +			goto close_handles;
> +
> +		/* We've run out of free low memory. */
> +		if (initrd_addr > hdr->initrd_addr_max) {
> +			status = EFI_INVALID_PARAMETER;
> +			goto free_initrd_total;
> +		}
> +
> +		addr = initrd_addr;
> +		for (j = 0; j < nr_initrds; j++) {
> +			u64 size;
> +
> +			size = initrds[j].size;
> +			status = efi_call_phys3(fh->read, initrds[j].handle,
> +						&size, addr);
> +			if (status != EFI_SUCCESS)
> +				goto free_initrd_total;
> +
> +			efi_call_phys1(fh->close, initrds[j].handle);
> +
> +			addr += size;
> +		}
> +
> +	}
> +
> +	efi_call_phys1(sys_table->boottime->free_pool, initrds);
> +
> +	hdr->ramdisk_image = initrd_addr;
> +	hdr->ramdisk_size = initrd_total;
> +
> +	return status;
> +
> +free_initrd_total:
> +	low_free(initrd_total, initrd_addr);
> +
> +close_handles:
> +	for (k = j; k < nr_initrds; k++)
> +		efi_call_phys1(fh->close, initrds[k].handle);
> +free_initrds:
> +	efi_call_phys1(sys_table->boottime->free_pool, initrds);
> +fail:
> +	hdr->ramdisk_image = 0;
> +	hdr->ramdisk_size = 0;
> +
> +	return status;
> +}
> +
> +/*
> + * Because the x86 boot code expects to be passed a boot_params we
> + * need to create one ourselves (usually the bootloader would create
> + * one for us).
> + */
> +static efi_status_t make_boot_params(struct boot_params *boot_params,
> +				     efi_loaded_image_t *image,
> +				     void *handle)
> +{
> +	struct efi_info *efi = &boot_params->efi_info;
> +	struct apm_bios_info *bi = &boot_params->apm_bios_info;
> +	struct sys_desc_table *sdt = &boot_params->sys_desc_table;
> +	struct e820entry *e820_map = &boot_params->e820_map[0];
> +	struct e820entry *prev = NULL;
> +	struct setup_header *hdr = &boot_params->hdr;
> +	unsigned long size, key, desc_size, _size;
> +	efi_memory_desc_t *mem_map;
> +	void *options = image->load_options;
> +	u32 load_options_size = image->load_options_size / 2; /* ASCII */
> +	int options_size = 0;
> +	efi_status_t status;
> +	__u32 desc_version;
> +	unsigned long cmdline;
> +	u8 nr_entries;
> +	u16 *s2;
> +	u8 *s1;
> +	int i;
> +
> +	hdr->type_of_loader = 0x21;
> +
> +	/* Convert unicode cmdline to ascii */
> +	cmdline = 0;
> +	s2 = (u16 *)options;
> +
> +	if (s2) {
> +		while (*s2 && *s2 != '\n' && options_size < load_options_size) {
> +			s2++;
> +			options_size++;
> +		}
> +
> +		if (options_size) {
> +			if (options_size > hdr->cmdline_size)
> +				options_size = hdr->cmdline_size;
> +
> +			options_size++;	/* NUL termination */
> +
> +			status = low_alloc(options_size, 1, &cmdline);
> +			if (status != EFI_SUCCESS)
> +				goto fail;
Shouldn't this be options_size + 1?
> +
> +			s1 = (u8 *)(unsigned long)cmdline;
> +			s2 = (u16 *)options;
> +
> +			for (i = 0; i < options_size - 1; i++)
> +				*s1++ = *s2++;
> +
> +			*s1 = '\0';
For this null character..
> +		}
> +	}
> +
> +	hdr->cmd_line_ptr = cmdline;
> +
> +	hdr->ramdisk_image = 0;
> +	hdr->ramdisk_size = 0;
> +
> +	status = handle_ramdisks(image, hdr);
> +	if (status != EFI_SUCCESS)
> +		goto free_cmdline;
> +
> +	setup_graphics(boot_params);
> +
> +	/* Clear APM BIOS info */
> +	memset(bi, 0, sizeof(*bi));
> +
> +	memset(sdt, 0, sizeof(*sdt));
> +
> +	memcpy(&efi->efi_loader_signature, EFI_LOADER_SIGNATURE, sizeof(__u32));
> +
> +	size = sizeof(*mem_map) * 32;
> +
> +again:
> +	size += sizeof(*mem_map);
> +	_size = size;
> +	status = low_alloc(size, 1, (unsigned long *)&mem_map);
> +	if (status != EFI_SUCCESS)
> +		goto free_cmdline;
> +
> +	status = efi_call_phys5(sys_table->boottime->get_memory_map, &size,
> +				mem_map, &key, &desc_size, &desc_version);
> +	if (status == EFI_BUFFER_TOO_SMALL) {
> +		low_free(_size, (unsigned long)mem_map);
> +		goto again;
> +	}
> +
> +	if (status != EFI_SUCCESS)
> +		goto free_mem_map;
> +
> +	efi->efi_systab = (unsigned long)sys_table;
> +	efi->efi_memdesc_size = desc_size;
> +	efi->efi_memdesc_version = desc_version;
> +	efi->efi_memmap = (unsigned long)mem_map;
> +	efi->efi_memmap_size = size;
> +
> +#ifdef CONFIG_X86_64
> +	efi->efi_systab_hi = (unsigned long)sys_table >> 32;
> +	efi->efi_memmap_hi = (unsigned long)mem_map >> 32;
> +#endif
> +
> +	/* Might as well exit boot services now */
> +	status = efi_call_phys2(sys_table->boottime->exit_boot_services,
> +				handle, key);
> +	if (status != EFI_SUCCESS)
> +		goto free_mem_map;
> +
> +	/* Historic? */
> +	boot_params->alt_mem_k = 32 * 1024;
> +
> +	/*
> +	 * Convert the EFI memory map to E820.
> +	 */
> +	nr_entries = 0;
> +	for (i = 0; i < size / desc_size; i++) {
> +		efi_memory_desc_t *d;
> +		unsigned int e820_type = 0;
> +
> +		d = (efi_memory_desc_t *)((unsigned long)mem_map + (i * desc_size));
> +		switch(d->type) {
> +		case EFI_RESERVED_TYPE:
> +		case EFI_RUNTIME_SERVICES_CODE:
> +		case EFI_RUNTIME_SERVICES_DATA:
> +		case EFI_MEMORY_MAPPED_IO:
> +		case EFI_MEMORY_MAPPED_IO_PORT_SPACE:
> +		case EFI_PAL_CODE:
> +			e820_type = E820_RESERVED;
> +			break;
> +
> +		case EFI_UNUSABLE_MEMORY:
> +			e820_type = E820_UNUSABLE;
> +			break;
> +
> +		case EFI_ACPI_RECLAIM_MEMORY:
> +			e820_type = E820_ACPI;
> +			break;
> +
> +		case EFI_LOADER_CODE:
> +		case EFI_LOADER_DATA:
> +		case EFI_BOOT_SERVICES_CODE:
> +		case EFI_BOOT_SERVICES_DATA:
> +		case EFI_CONVENTIONAL_MEMORY:
> +			e820_type = E820_RAM;
> +			break;
> +
> +		case EFI_ACPI_MEMORY_NVS:
> +			e820_type = E820_NVS;
> +			break;
> +
> +		default:
> +			continue;
> +		}
> +
> +		/* Merge adjacent mappings */
> +		if (prev && prev->type == e820_type &&
> +		    (prev->addr + prev->size) == d->phys_addr)
> +			prev->size += d->num_pages << 12;
> +		else {
> +			e820_map->addr = d->phys_addr;
> +			e820_map->size = d->num_pages << 12;
> +			e820_map->type = e820_type;
> +			prev = e820_map++;
> +			nr_entries++;
> +		}
> +	}
> +
> +	boot_params->e820_entries = nr_entries;
> +
> +	return EFI_SUCCESS;
> +
> +free_mem_map:
> +	low_free(_size, (unsigned long)mem_map);
> +free_cmdline:
> +	if (options_size)
> +		low_free(options_size, hdr->cmd_line_ptr);
> +fail:
> +	return status;
> +}
> +
> +/*
> + * On success we return a pointer to a boot_params structure, and NULL
> + * on failure.
> + */
> +struct boot_params *efi_main(void *handle, efi_system_table_t *_table)
> +{
> +	struct boot_params *boot_params;
> +	unsigned long start, nr_pages;
> +	struct desc_ptr *gdt, *idt;
> +	efi_loaded_image_t *image;
> +	struct setup_header *hdr;
> +	efi_status_t status;
> +	efi_guid_t proto = LOADED_IMAGE_PROTOCOL_GUID;
> +	struct desc_struct *desc;
> +
> +	sys_table = _table;
> +
> +	/* Check if we were booted by the EFI firmware */
> +	if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
> +		goto fail;
> +
> +	status = efi_call_phys3(sys_table->boottime->handle_protocol,
> +				handle, &proto, (void *)&image);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	status = low_alloc(0x4000, 1, (unsigned long *)&boot_params);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	memset(boot_params, 0x0, 0x4000);
> +
> +	/* Copy first two sectors to boot_params */
> +	memcpy(boot_params, image->image_base, 1024);
> +
> +	hdr = &boot_params->hdr;
> +
> +	/*
> +	 * The EFI firmware loader could have placed the kernel image
> +	 * anywhere in memory, but the kernel has various restrictions
> +	 * on the max physical address it can run at. Attempt to move
> +	 * the kernel to boot_params.pref_address, or as low as
> +	 * possible.
> +	 */
> +	start = hdr->pref_address;
> +	nr_pages = round_up(hdr->init_size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
> +
> +	status = efi_call_phys4(sys_table->boottime->allocate_pages,
> +				EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA,
> +				nr_pages, &start);
> +	if (status != EFI_SUCCESS) {
> +		status = low_alloc(hdr->init_size, hdr->kernel_alignment,
> +				   &start);
> +		if (status != EFI_SUCCESS)
> +			goto fail;
> +	}
> +
> +	hdr->code32_start = (__u32)start;
> +	hdr->pref_address = (__u64)(unsigned long)image->image_base;
> +
> +	memcpy((void *)start, image->image_base, image->image_size);
> +
> +	status = efi_call_phys3(sys_table->boottime->allocate_pool,
> +				EFI_LOADER_DATA, sizeof(*gdt),
> +				(void **)&gdt);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	gdt->size = 0x800;
> +	status = low_alloc(gdt->size, 8, (unsigned long *)&gdt->address);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	status = efi_call_phys3(sys_table->boottime->allocate_pool,
> +				EFI_LOADER_DATA, sizeof(*idt),
> +				(void **)&idt);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	idt->size = 0;
> +	idt->address = 0;
> +
> +	status = make_boot_params(boot_params, image, handle);
> +	if (status != EFI_SUCCESS)
> +		goto fail;
> +
> +	memset((char *)gdt->address, 0x0, gdt->size);
> +	desc = (struct desc_struct *)gdt->address;
> +
> +	/* The first GDT is a dummy and the second is unused. */
> +	desc += 2;
> +
> +	desc->limit0 = 0xffff;
> +	desc->base0 = 0x0000;
> +	desc->base1 = 0x0000;
> +	desc->type = SEG_TYPE_CODE | SEG_TYPE_EXEC_READ;
> +	desc->s = DESC_TYPE_CODE_DATA;
> +	desc->dpl = 0;
> +	desc->p = 1;
> +	desc->limit = 0xf;
> +	desc->avl = 0;
> +	desc->l = 0;
> +	desc->d = SEG_OP_SIZE_32BIT;
> +	desc->g = SEG_GRANULARITY_4KB;
> +	desc->base2 = 0x00;
> +
> +	desc++;
> +	desc->limit0 = 0xffff;
> +	desc->base0 = 0x0000;
> +	desc->base1 = 0x0000;
> +	desc->type = SEG_TYPE_DATA | SEG_TYPE_READ_WRITE;
> +	desc->s = DESC_TYPE_CODE_DATA;
> +	desc->dpl = 0;
> +	desc->p = 1;
> +	desc->limit = 0xf;
> +	desc->avl = 0;
> +	desc->l = 0;
> +	desc->d = SEG_OP_SIZE_32BIT;
> +	desc->g = SEG_GRANULARITY_4KB;
> +	desc->base2 = 0x00;
> +
> +#ifdef CONFIG_X86_64
> +	/* Task segment value */
> +	desc++;
> +	desc->limit0 = 0x0000;
> +	desc->base0 = 0x0000;
> +	desc->base1 = 0x0000;
> +	desc->type = SEG_TYPE_TSS;
> +	desc->s = 0;
> +	desc->dpl = 0;
> +	desc->p = 1;
> +	desc->limit = 0x0;
> +	desc->avl = 0;
> +	desc->l = 0;
> +	desc->d = 0;
> +	desc->g = SEG_GRANULARITY_4KB;
> +	desc->base2 = 0x00;
> +#endif /* CONFIG_X86_64 */
> +
> +	asm volatile ("lidt %0" :: "m" (*idt));
> +	asm volatile ("lgdt %0" :: "m" (*gdt));
> +
> +	asm volatile("cli");
> +
> +	return boot_params;
> +fail:
> +	return NULL;
> +}
> diff --git a/arch/x86/boot/compressed/efi_stub_32.S b/arch/x86/boot/compressed/efi_stub_32.S
> new file mode 100644
> index 0000000..5047cd9
> --- /dev/null
> +++ b/arch/x86/boot/compressed/efi_stub_32.S
> @@ -0,0 +1,87 @@
> +/*
> + * EFI call stub for IA32.
> + *
> + * This stub allows us to make EFI calls in physical mode with interrupts
> + * turned off. Note that this implementation is different from the one in
> + * arch/x86/platform/efi/efi_stub_32.S because we're _already_ in physical
> + * mode at this point.
> + */
> +
> +#include <linux/linkage.h>
> +#include <asm/page_types.h>
> +
> +/*
> + * efi_call_phys(void *, ...) is a function with variable parameters.
> + * All the callers of this function assure that all the parameters are 4-bytes.
> + */
> +
> +/*
> + * In gcc calling convention, EBX, ESP, EBP, ESI and EDI are all callee save.
> + * So we'd better save all of them at the beginning of this function and restore
> + * at the end no matter how many we use, because we can not assure EFI runtime
> + * service functions will comply with gcc calling convention, too.
> + */
> +
> +.text
> +ENTRY(efi_call_phys)
> +	/*
> +	 * 0. The function can only be called in Linux kernel. So CS has been
> +	 * set to 0x0010, DS and SS have been set to 0x0018. In EFI, I found
> +	 * the values of these registers are the same. And, the corresponding
> +	 * GDT entries are identical. So I will do nothing about segment reg
> +	 * and GDT, but change GDT base register in prelog and epilog.
> +	 */
> +
> +	/*
> +	 * 1. Because we haven't been relocated by this point we need to
> +	 * use relative addressing.
> +	 */
> +	call	1f
> +1:	popl	%edx
> +	subl	$1b, %edx
> +
> +	/*
> +	 * 2. Now on the top of stack is the return
> +	 * address in the caller of efi_call_phys(), then parameter 1,
> +	 * parameter 2, ..., param n. To make things easy, we save the return
> +	 * address of efi_call_phys in a global variable.
> +	 */
> +	popl	%ecx
> +	movl	%ecx, saved_return_addr(%edx)
> +	/* get the function pointer into ECX*/
> +	popl	%ecx
> +	movl	%ecx, efi_rt_function_ptr(%edx)
> +
> +	/*
> +	 * 3. Call the physical function.
> +	 */
> +	call	*%ecx
> +
> +	/*
> +	 * 4. Balance the stack. And because EAX contain the return value,
> +	 * we'd better not clobber it. We need to calculate our address
> +	 * again because %ecx and %edx are not preserved across EFI function
> +	 * calls.
> +	 */
> +	call	1f
> +1:	popl	%edx
> +	subl	$1b, %edx
> +
> +	movl	efi_rt_function_ptr(%edx), %ecx
> +	pushl	%ecx
> +
> +	/*
> +	 * 10. Push the saved return address onto the stack and return.
> +	 */
> +	movl	saved_return_addr(%edx), %ecx
> +	pushl	%ecx
> +	ret
> +ENDPROC(efi_call_phys)
> +.previous
> +
> +.data
> +saved_return_addr:
> +	.long 0
> +efi_rt_function_ptr:
> +	.long 0
> +
> diff --git a/arch/x86/boot/compressed/efi_stub_64.S b/arch/x86/boot/compressed/efi_stub_64.S
> new file mode 100644
> index 0000000..cedc60d
> --- /dev/null
> +++ b/arch/x86/boot/compressed/efi_stub_64.S
> @@ -0,0 +1 @@
> +#include "../../platform/efi/efi_stub_64.S"
> diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
> index 67a655a..a055993 100644
> --- a/arch/x86/boot/compressed/head_32.S
> +++ b/arch/x86/boot/compressed/head_32.S
> @@ -32,6 +32,28 @@
>  
>  	__HEAD
>  ENTRY(startup_32)
> +#ifdef CONFIG_EFI_STUB
> +	/*
> +	 * We don't need the return address, so set up the stack so
> +	 * efi_main() can find its arugments.
> +	 */
> +	add	$0x4, %esp
> +
> +	call	efi_main
> +	cmpl	$0, %eax
> +	je	preferred_addr
> +	movl	%eax, %esi
> +	call	1f
> +1:
> +	popl	%eax
> +	subl	$1b, %eax
> +	subl	BP_pref_address(%esi), %eax
> +	add	BP_code32_start(%esi), %eax
> +	leal	preferred_addr(%eax), %eax
> +	jmp	*%eax
> +
> +preferred_addr:
> +#endif
>  	cld
>  	/*
>  	 * Test KEEP_SEGMENTS flag to see if the bootloader is asking
> diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
> index 35af09d..558d76c 100644
> --- a/arch/x86/boot/compressed/head_64.S
> +++ b/arch/x86/boot/compressed/head_64.S
> @@ -199,6 +199,26 @@ ENTRY(startup_64)
>  	 * an identity mapped page table being provied that maps our
>  	 * entire text+data+bss and hopefully all of memory.
>  	 */
> +#ifdef CONFIG_EFI_STUB
> +	pushq	%rsi
> +	mov	%rcx, %rdi
> +	mov	%rdx, %rsi
> +	call	efi_main
> +	popq	%rsi
> +	cmpq	$0,%rax
> +	je	preferred_addr
> +	movq	%rax,%rsi
> +	call	1f
> +1:
> +	popq	%rax
> +	subq	$1b, %rax
> +	subq	BP_pref_address(%rsi), %rax
> +	add	BP_code32_start(%esi), %eax
> +	leaq	preferred_addr(%rax), %rax
> +	jmp	*%rax
> +
> +preferred_addr:
> +#endif
>  
>  	/* Setup data segments. */
>  	xorl	%eax, %eax
> diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c
> index 19b3e69..ffb9c5c 100644
> --- a/arch/x86/boot/compressed/string.c
> +++ b/arch/x86/boot/compressed/string.c
> @@ -1,2 +1,11 @@
>  #include "misc.h"
> +
> +int memcmp(const void *s1, const void *s2, size_t len)
> +{
> +	u8 diff;
> +	asm("repe; cmpsb; setnz %0"
> +	    : "=qm" (diff), "+D" (s1), "+S" (s2), "+c" (len));
> +	return diff;
> +}
> +
>  #include "../string.c"
> diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
> index 93e689f..c4756f6 100644
> --- a/arch/x86/boot/header.S
> +++ b/arch/x86/boot/header.S
> @@ -45,6 +45,11 @@ SYSSEG		= 0x1000		/* historical load address >> 4 */
>  
>  	.global bootsect_start
>  bootsect_start:
> +#ifdef CONFIG_EFI_STUB
> +	# "MZ", MS-DOS header
> +	.byte 0x4d
> +	.byte 0x5a
> +#endif
>  
>  	# Normalize the start address
>  	ljmp	$BOOTSEG, $start2
> @@ -79,6 +84,14 @@ bs_die:
>  	# invoke the BIOS reset code...
>  	ljmp	$0xf000,$0xfff0
>  
> +#ifdef CONFIG_EFI_STUB
> +	.org	0x3c
> +	#
> +	# Offset to the PE header.
> +	#
> +	.long	pe_header
> +#endif /* CONFIG_EFI_STUB */
> +
>  	.section ".bsdata", "a"
>  bugger_off_msg:
>  	.ascii	"Direct booting from floppy is no longer supported.\r\n"
> @@ -87,6 +100,141 @@ bugger_off_msg:
>  	.ascii	"Remove disk and press any key to reboot . . .\r\n"
>  	.byte	0
>  
> +#ifdef CONFIG_EFI_STUB
> +pe_header:
> +	.ascii	"PE"
> +	.word 	0
> +
> +coff_header:
> +#ifdef CONFIG_X86_32
> +	.word	0x14c				# i386
> +#else
> +	.word	0x8664				# x86-64
> +#endif
> +	.word	2				# nr_sections
> +	.long	0 				# TimeDateStamp
> +	.long	0				# PointerToSymbolTable
> +	.long	1				# NumberOfSymbols
> +	.word	section_table - optional_header	# SizeOfOptionalHeader
> +#ifdef CONFIG_X86_32
> +	.word	0x306				# Characteristics.
> +						# IMAGE_FILE_32BIT_MACHINE |
> +						# IMAGE_FILE_DEBUG_STRIPPED |
> +						# IMAGE_FILE_EXECUTABLE_IMAGE |
> +						# IMAGE_FILE_LINE_NUMS_STRIPPED
> +#else
> +	.word	0x206				# Characteristics
> +						# IMAGE_FILE_DEBUG_STRIPPED |
> +						# IMAGE_FILE_EXECUTABLE_IMAGE |
> +						# IMAGE_FILE_LINE_NUMS_STRIPPED
> +#endif
> +
> +optional_header:
> +#ifdef CONFIG_X86_32
> +	.word	0x10b				# PE32 format
> +#else
> +	.word	0x20b 				# PE32+ format
> +#endif
> +	.byte	0x02				# MajorLinkerVersion
> +	.byte	0x14				# MinorLinkerVersion
> +
> +	# Filled in by build.c
> +	.long	0				# SizeOfCode
> +
> +	.long	0				# SizeOfInitializedData
> +	.long	0				# SizeOfUninitializedData
> +
> +	# Filled in by build.c
> +	.long	0x0000				# AddressOfEntryPoint
> +
> +	.long	0x0000				# BaseOfCode
> +#ifdef CONFIG_X86_32
> +	.long	0				# data
> +#endif
> +
> +extra_header_fields:
> +#ifdef CONFIG_X86_32
> +	.long	0				# ImageBase
> +#else
> +	.quad	0				# ImageBase
> +#endif
> +	.long	0x1000				# SectionAlignment
> +	.long	0x200				# FileAlignment
> +	.word	0				# MajorOperatingSystemVersion
> +	.word	0				# MinorOperatingSystemVersion
> +	.word	0				# MajorImageVersion
> +	.word	0				# MinorImageVersion
> +	.word	0				# MajorSubsystemVersion
> +	.word	0				# MinorSubsystemVersion
> +	.long	0				# Win32VersionValue
> +
> +	#
> +	# The size of the bzImage is written in tools/build.c
> +	#
> +	.long	0				# SizeOfImage
> +
> +	.long	0x200				# SizeOfHeaders
> +	.long	0				# CheckSum
> +	.word	0xa				# Subsystem (EFI application)
> +	.word	0				# DllCharacteristics
> +#ifdef CONFIG_X86_32
> +	.long	0				# SizeOfStackReserve
> +	.long	0				# SizeOfStackCommit
> +	.long	0				# SizeOfHeapReserve
> +	.long	0				# SizeOfHeapCommit
> +#else
> +	.quad	0				# SizeOfStackReserve
> +	.quad	0				# SizeOfStackCommit
> +	.quad	0				# SizeOfHeapReserve
> +	.quad	0				# SizeOfHeapCommit
> +#endif
> +	.long	0				# LoaderFlags
> +	.long	0x1				# NumberOfRvaAndSizes
> +
> +	.quad	0				# ExportTable
> +	.quad	0				# ImportTable
> +	.quad	0				# ResourceTable
> +	.quad	0				# ExceptionTable
> +	.quad	0				# CertificationTable
> +	.quad	0				# BaseRelocationTable
> +
> +	# Section table
> +section_table:
> +	.ascii	".text"
> +	.byte	0
> +	.byte	0
> +	.byte	0
> +	.long	0
> +	.long	0x0				# startup_{32,64}
> +	.long	0				# Size of initialized data
> +						# on disk
> +	.long	0x0				# startup_{32,64}
> +	.long	0				# PointerToRelocations
> +	.long	0				# PointerToLineNumbers
> +	.word	0				# NumberOfRelocations
> +	.word	0				# NumberOfLineNumbers
> +	.long	0x60500020			# Characteristics (section flags)
> +
> +	#
> +	# The EFI application loader requires a relocation section
> +	# because EFI applications are relocatable and not having
> +	# this section seems to confuse it. But since we don't need
> +	# the loader to fixup any relocs for us just fill it with a
> +	# single dummy reloc.
> +	#
> +	.ascii	".reloc"
> +	.byte	0
> +	.byte	0
> +	.long	reloc_end - reloc_start
> +	.long	reloc_start
> +	.long	reloc_end - reloc_start		# SizeOfRawData
> +	.long	reloc_start			# PointerToRawData
> +	.long	0				# PointerToRelocations
> +	.long	0				# PointerToLineNumbers
> +	.word	0				# NumberOfRelocations
> +	.word	0				# NumberOfLineNumbers
> +	.long	0x42100040			# Characteristics (section flags)
> +#endif /* CONFIG_EFI_STUB */
>  
>  	# Kernel attributes; used by setup.  This is part 1 of the
>  	# header, from the old boot sector.
> @@ -318,3 +466,13 @@ die:
>  setup_corrupt:
>  	.byte	7
>  	.string	"No setup signature found...\n"
> +
> +	.data
> +dummy:	.long	0
> +
> +	.section .reloc
> +reloc_start:
> +	.long	dummy - reloc_start
> +	.long	10
> +	.word	0
> +reloc_end:
> diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
> index 3cbc405..574dedf 100644
> --- a/arch/x86/boot/string.c
> +++ b/arch/x86/boot/string.c
> @@ -111,3 +111,38 @@ unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int bas
>  
>  	return result;
>  }
> +
> +/**
> + * strlen - Find the length of a string
> + * @s: The string to be sized
> + */
> +size_t strlen(const char *s)
> +{
> +	const char *sc;
> +
> +	for (sc = s; *sc != '\0'; ++sc)
> +		/* nothing */;
> +	return sc - s;
> +}
> +
> +/**
> + * strstr - Find the first substring in a %NUL terminated string
> + * @s1: The string to be searched
> + * @s2: The string to search for
> + */
> +char *strstr(const char *s1, const char *s2)
> +{
> +	size_t l1, l2;
> +
> +	l2 = strlen(s2);
> +	if (!l2)
> +		return (char *)s1;
> +	l1 = strlen(s1);
> +	while (l1 >= l2) {
> +		l1--;
> +		if (!memcmp(s1, s2, l2))
> +			return (char *)s1;
> +		s1++;
> +	}
> +	return NULL;
> +}
> diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
> index fdc60a0..4e9bd6b 100644
> --- a/arch/x86/boot/tools/build.c
> +++ b/arch/x86/boot/tools/build.c
> @@ -135,6 +135,9 @@ static void usage(void)
>  
>  int main(int argc, char ** argv)
>  {
> +#ifdef CONFIG_EFI_STUB
> +	unsigned int file_sz, pe_header;
> +#endif
>  	unsigned int i, sz, setup_sectors;
>  	int c;
>  	u32 sys_size;
> @@ -194,6 +197,42 @@ int main(int argc, char ** argv)
>  	buf[0x1f6] = sys_size >> 16;
>  	buf[0x1f7] = sys_size >> 24;
>  
> +#ifdef CONFIG_EFI_STUB
> +	file_sz = sz + i + ((sys_size * 16) - sz);
> +
> +	pe_header = *(unsigned int *)&buf[0x3c];
> +
> +	/* Size of code */
> +	*(unsigned int *)&buf[pe_header + 0x1c] = file_sz;
> +
> +	/* Size of image */
> +	*(unsigned int *)&buf[pe_header + 0x50] = file_sz;
> +
> +#ifdef CONFIG_X86_32
> +	/* Address of entry point */
> +	*(unsigned int *)&buf[pe_header + 0x28] = i;
> +
> +	/* .text size */
> +	*(unsigned int *)&buf[pe_header + 0xb0] = file_sz;
> +
> +	/* .text size of initialised data */
> +	*(unsigned int *)&buf[pe_header + 0xb8] = file_sz;
> +#else
> +	/*
> +	 * Address of entry point. startup_32 is at the beginning and
> +	 * the 64-bit entry point (startup_64) is always 512 bytes
> +	 * after.
> +	 */
> +	*(unsigned int *)&buf[pe_header + 0x28] = i + 512;
> +
> +	/* .text size */
> +	*(unsigned int *)&buf[pe_header + 0xc0] = file_sz;
> +
> +	/* .text size of initialised data */
> +	*(unsigned int *)&buf[pe_header + 0xc8] = file_sz;
> +#endif /* CONFIG_X86_32 */
> +#endif /* CONFIG_EFI_STUB */
> +
>  	crc = partial_crc32(buf, i, crc);
>  	if (fwrite(buf, 1, i, stdout) != i)
>  		die("Writing setup failed");
> diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
> index 4f13faf..68de2dc 100644
> --- a/arch/x86/kernel/asm-offsets.c
> +++ b/arch/x86/kernel/asm-offsets.c
> @@ -67,4 +67,6 @@ void common(void) {
>  	OFFSET(BP_hardware_subarch, boot_params, hdr.hardware_subarch);
>  	OFFSET(BP_version, boot_params, hdr.version);
>  	OFFSET(BP_kernel_alignment, boot_params, hdr.kernel_alignment);
> +	OFFSET(BP_pref_address, boot_params, hdr.pref_address);
> +	OFFSET(BP_code32_start, boot_params, hdr.code32_start);
>  }

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