x86 EFI boot stub

From: Matt Fleming <[email protected]>

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 <[email protected]>

Cc Thomas Gleixner <[email protected]>

Cc Ingo Molnar <[email protected]>

Cc Mike Waychison <[email protected]>

Cc Matthew Garrett <[email protected]>

Cc Andi Kleen <[email protected]>

Cc Maarten Lankhorst <[email protected]>

Tested-by Henrik Rydberg <[email protected]>

Signed-off-by Matt Fleming <[email protected]>

---

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 ‘main’:
arch/x86/boot/tools/build.c:138:24: warning: unused variable ‘pe_header’ arch/x86/boot/tools/build.c:138:15: warning: unused variable ‘file_sz’

- 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

arch/x86/Kconfig +7 -0

index 6a47bb2..d40c876 100644
@@ -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"

arch/x86/boot/compressed/Makefile +9 -1

index 09664ef..b123b9a 100644
@@ -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)
 	@:
 

arch/x86/boot/compressed/eboot.c new file +680 -0

new file mode 100644
index 0000000..f84e389
@@ -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++;
+		}

arch/x86/boot/compressed/eboot.c new file +277 -0

+		}
+	}
+
+	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;
+}

arch/x86/boot/compressed/efi_stub_32.S new file +87 -0

new file mode 100644
index 0000000..5047cd9
@@ -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
+

arch/x86/boot/compressed/efi_stub_64.S new file +1 -0

new file mode 100644
index 0000000..cedc60d
@@ -0,0 +1 @@
+#include "../../platform/efi/efi_stub_64.S"

arch/x86/boot/compressed/head_32.S +22 -0

index 67a655a..a055993 100644
@@ -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

arch/x86/boot/compressed/head_64.S +20 -0

index 35af09d..558d76c 100644
@@ -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

arch/x86/boot/compressed/string.c +9 -0

index 19b3e69..ffb9c5c 100644
@@ -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"

arch/x86/boot/header.S +158 -0

index 93e689f..c4756f6 100644
@@ -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:

arch/x86/boot/string.c +35 -0

index 3cbc405..574dedf 100644
@@ -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;
+}

arch/x86/boot/tools/build.c +39 -0

index fdc60a0..4e9bd6b 100644
@@ -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");

arch/x86/kernel/asm-offsets.c +2 -0

index 4f13faf..68de2dc 100644
@@ -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);
 }

arch/x86/boot/compressed/eboot.c line 690

Quoted 9 lines

arch/x86/boot/compressed/eboot.c new file +9 -0

+		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?

arch/x86/boot/compressed/eboot.c line 696

Quoted 6 lines

arch/x86/boot/compressed/eboot.c new file +6 -0

+
+			s1 = (u8 *)(unsigned long)cmdline;
+			s2 = (u16 *)options;
+
+			for (i = 0; i < options_size - 1; i++)
+				*s1++ = *s2++;

arch/x86/boot/compressed/eboot.c line 698

Quoted 2 lines

arch/x86/boot/compressed/eboot.c new file +2 -0

+
+			*s1 = '\0';

For this null character..

arch/x86/boot/compressed/eboot.c line 690

Quoted 3 lines

arch/x86/boot/compressed/eboot.c new file +3 -0

+			status = low_alloc(options_size, 1, &cmdline);
+			if (status != EFI_SUCCESS)
+				goto fail;

Shouldn't this be options_size + 1?

arch/x86/boot/compressed/eboot.c line 698

Quoted 8 lines

arch/x86/boot/compressed/eboot.c new file +8 -0

+
+			s1 = (u8 *)(unsigned long)cmdline;
+			s2 = (u16 *)options;
+
+			for (i = 0; i < options_size - 1; i++)
+				*s1++ = *s2++;
+
+			*s1 = '\0';

For this null character..

Review

Quoted 1 line

(quoted diff) +1 -0

+		}

From: Matt Fleming <[email protected]>

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

Seems initrd is failing for me. Is there any limitation on the size of the initrd? The default one fedora generates for my kernel is 46mb. It loads the kernel, but it reboots before it gets to userspace. Loading the kernel and initrd with grub2-efi works. EFI booting without initrd works too.

From 5f1a572e59915daaa263093f0a2f180c88fa8504 Mon Sep 17 00:00:00 2001

Quoted 5 lines · Maarten Lankhorst

Seems initrd is failing for me. Is there any limitation on the size of the initrd? The default one fedora generates for my kernel is 46mb. It loads the kernel, but it reboots before it gets to userspace. Loading the kernel and initrd with grub2-efi works. EFI booting without initrd works too.

Sorry it took me so long to reply to this! Could you try version 6 of this patch?

From 5f1a572e59915daaa263093f0a2f180c88fa8504 Mon Sep 17 00:00:00 2001
From: Matt Fleming <[email protected]>
Date: Wed, 20 Jul 2011 09:24:53 +0100
Subject: [PATCH v6] x86, efi: EFI boot stub support
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

v6:

- Try to allocate initrd memory just below hdr->inird_addr_max.

When I tested this with v3.2-rc2 it didn't boot, it hung before it initialized the kernel.
Without initrd it works fine, though.

Quoted 3 lines · Maarten Lankhorst

When I tested this with v3.2-rc2 it didn't boot, it hung before it initialized the kernel.
Without initrd it works fine, though.

Bah, so this change actually makes booting worse? You said before that you almost made it to userspace but this seems to hang much earlier now. Is that correct?

... back to the drawing board.

Hey Matt,

Quoted 8 lines · Matt Fleming

Quoted 3 lines · Maarten Lankhorst

When I tested this with v3.2-rc2 it didn't boot, it hung before it initialized the kernel.
Without initrd it works fine, though.

Bah, so this change actually makes booting worse? You said before that you almost made it to userspace but this seems to hang much earlier now. Is that correct?

Quoted 1 line

... back to the drawing board.

I was looking at why grub2 could boot, seems to be it reads in chunks of 256 kilobytes. I seem to be able to get it to boot with chunks of 4 mb as well, but didn't test beyond that.

So the fix is to simply read the file in parts, otherwise efi hangs.. As a nice side effect, short reads are also handled, but the efi firmware seems to choke over huge reads and dies.

Hey Matt,

Quoted 8 lines · Matt Fleming

Quoted 3 lines · Maarten Lankhorst

When I tested this with v3.2-rc2 it didn't boot, it hung before it initialized the kernel.
Without initrd it works fine, though.

Bah, so this change actually makes booting worse? You said before that you almost made it to userspace but this seems to hang much earlier now. Is that correct?

Quoted 1 line

... back to the drawing board.

I was looking at why grub2 could boot, seems to be it reads in chunks of 256 kilobytes. I seem to be able to get it to boot with chunks of 4 mb as well, but didn't test beyond that.

So the fix is to simply read the file in parts, otherwise efi hangs.. As a nice side effect, short reads are also handled, but the efi firmware seems to choke over huge reads and dies.

Thanks a lot for diagnosing this, Maarten! The copy of grub that I have (fedora's version) looks like it uses the disk_io protocol to read from disks, I wonder if there's a reason for this. I Cc'd Peter Jones in case he's seen anything like this before.

grub needs to be able to read files off filesystems that may not be supported by the UEFI implementation, so has its own filesystem drivers that use disk_io.

From elilo source code:

The efi boot stub tries to read the entire initrd in 1 go, however some efi implementations hang if too much if asked to read too much data at the same time. After some experimentation I found out that my asrock p67 board will hang if asked to read chunks of 4mb, so use a safe value.

From elilo source code:
/*
* We load by chunks rather than a single big read because
* early versions of EFI had troubles loading files
* from floppies in a single big request. Breaking
* the read down into chunks of 4KB fixed that
* problem. While this problem has been fixed, we still prefer
* this method because it tells us whether or not we're making
* forward progress.
*/

While the comment says 4KB, it's using 4 * EFI_PAGE_SIZE (16KB), so I went by the safest route of following elilo here.

Signed-off-by Maarten Lankhorst <[email protected]>

---
 arch/x86/boot/compressed/eboot.c |   20 ++++++++++++++------
 1 files changed, 14 insertions(+), 6 deletions(-)

Quoted 17 lines · Maarten Lankhorst

The efi boot stub tries to read the entire initrd in 1 go, however some efi implementations hang if too much if asked to read too much data at the same time. After some experimentation I found out that my asrock p67 board will hang if asked to read chunks of 4mb, so use a safe value.

From elilo source code:
/*
* We load by chunks rather than a single big read because
* early versions of EFI had troubles loading files
* from floppies in a single big request. Breaking
* the read down into chunks of 4KB fixed that
* problem. While this problem has been fixed, we still prefer
* this method because it tells us whether or not we're making
* forward progress.
*/

Quoted 3 lines

While the comment says 4KB, it's using 4 * EFI_PAGE_SIZE (16KB), so I went by the safest route of following elilo here.

Quoted 18 lines · Matt Fleming

Quoted 17 lines · Maarten Lankhorst

The efi boot stub tries to read the entire initrd in 1 go, however some efi implementations hang if too much if asked to read too much data at the same time. After some experimentation I found out that my asrock p67 board will hang if asked to read chunks of 4mb, so use a safe value.

From elilo source code:
/*
* We load by chunks rather than a single big read because
* early versions of EFI had troubles loading files
* from floppies in a single big request. Breaking
* the read down into chunks of 4KB fixed that
* problem. While this problem has been fixed, we still prefer
* this method because it tells us whether or not we're making
* forward progress.
*/

Quoted 3 lines

Quoted 3 lines

While the comment says 4KB, it's using 4 * EFI_PAGE_SIZE (16KB), so I went by the safest route of following elilo here.

I'm going to NAK this, because I think the performance impact is too severe. I would like to set the cap at 1 MiB for now, unless we can identify platforms where *that* is known to fail.

Maarten, would you be willing to rev your patch? Furthermore, please make the maximum chunksize a define.

Quoted 26 lines · H. Peter Anvin

Quoted 18 lines · Matt Fleming

Quoted 17 lines · Maarten Lankhorst

The efi boot stub tries to read the entire initrd in 1 go, however some efi implementations hang if too much if asked to read too much data at the same time. After some experimentation I found out that my asrock p67 board will hang if asked to read chunks of 4mb, so use a safe value.

From elilo source code:
/*
* We load by chunks rather than a single big read because
* early versions of EFI had troubles loading files
* from floppies in a single big request. Breaking
* the read down into chunks of 4KB fixed that
* problem. While this problem has been fixed, we still prefer
* this method because it tells us whether or not we're making
* forward progress.
*/

Quoted 3 lines

Quoted 3 lines

While the comment says 4KB, it's using 4 * EFI_PAGE_SIZE (16KB), so I went by the safest route of following elilo here.

I'm going to NAK this, because I think the performance impact is too severe. I would like to set the cap at 1 MiB for now, unless we can identify platforms where *that* is known to fail.

Quoted 3 lines

Maarten, would you be willing to rev your patch? Furthermore, please make the maximum chunksize a define.

One more thing, Maarten: could you please provide the full DMI information of the affected system?

When I was testing in increments of 1 mb, 4 mb was the magic number that caused a hang. My system runs fine with 1mb and my original patch used that as blocksize.