On 10/6/25 6:15 AM, [email protected] wrote:
> From: Chali Anis <[email protected]>
>
> The handover boot support is Linux-specific and can be disabled
> with CONFIG_EFI_HANDOVER_PROTOCOL. In preparation for adding a compliant
> boot method, move the handover-specific parts into their own file.
>
> Signed-off-by: Ahmad Fatoum <[email protected]>
> Signed-off-by: Chali Anis <[email protected]>
Reviewed-by: Ahmad Fatoum <[email protected]>
> ---
> efi/payload/Kconfig | 5 +
> efi/payload/Makefile | 1 +
> efi/payload/handover.c | 154 +++++++++++++++++++++++++++++
> efi/payload/image.c | 192 +++++--------------------------------
> efi/payload/image.h | 14 +++
> efi/payload/setup_header.h | 63 ++++++++++++
> 6 files changed, 260 insertions(+), 169 deletions(-)
> create mode 100644 efi/payload/handover.c
> create mode 100644 efi/payload/image.h
> create mode 100644 efi/payload/setup_header.h
>
> diff --git a/efi/payload/Kconfig b/efi/payload/Kconfig
> index a403acc81a93..d0a46704a6b9 100644
> --- a/efi/payload/Kconfig
> +++ b/efi/payload/Kconfig
> @@ -25,4 +25,9 @@ if EFI_PAYLOAD
> config EFI_STUB
> def_bool HAVE_EFI_STUB
>
> +config EFI_HANDOVER_PROTOCOL
> + bool "EFI Handover protocol"
> + default y
> + depends on X86
> +
> endif
> diff --git a/efi/payload/Makefile b/efi/payload/Makefile
> index 1250535302d3..d8b577bf3e23 100644
> --- a/efi/payload/Makefile
> +++ b/efi/payload/Makefile
> @@ -2,6 +2,7 @@
>
> obj-y += init.o
> obj-y += image.o
> +obj-$(CONFIG_EFI_HANDOVER_PROTOCOL) += handover.o
> obj-y += efi-initrd.o
> obj-$(CONFIG_OFTREE) += fdt.o
> bbenv-y += env-efi
> diff --git a/efi/payload/handover.c b/efi/payload/handover.c
> new file mode 100644
> index 000000000000..82f4cb4f5286
> --- /dev/null
> +++ b/efi/payload/handover.c
> @@ -0,0 +1,154 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * handover.c - legacy x86 EFI handover protocol
> + *
> + * Copyright (c) 2014 Sascha Hauer <[email protected]>, Pengutronix
> + */
> +
> +#define pr_fmt(fmt) "efi-handover: " fmt
> +
> +#include <clock.h>
> +#include <common.h>
> +#include <linux/sizes.h>
> +#include <linux/ktime.h>
> +#include <memory.h>
> +#include <command.h>
> +#include <magicvar.h>
> +#include <init.h>
> +#include <driver.h>
> +#include <io.h>
> +#include <efi.h>
> +#include <malloc.h>
> +#include <string.h>
> +#include <linux/err.h>
> +#include <boot.h>
> +#include <bootm.h>
> +#include <fs.h>
> +#include <libfile.h>
> +#include <binfmt.h>
> +#include <wchar.h>
> +#include <efi/efi-payload.h>
> +#include <efi/efi-device.h>
> +
> +#include "image.h"
> +#include "setup_header.h"
> +
> +static int efi_do_execute_image(enum filetype filetype, const char *file)
> +{
> + efi_handle_t handle;
> + struct efi_loaded_image *loaded_image;
> + int ret;
> +
> + ret = efi_load_image(file, &loaded_image, &handle);
> + if (ret)
> + return ret;
> +
> + return efi_execute_image(handle, loaded_image, filetype);
> +}
> +
> +typedef void(*handover_fn)(void *image, struct efi_system_table *table,
> + struct x86_setup_header *header);
> +
> +static inline void linux_efi_handover(efi_handle_t handle,
> + struct x86_setup_header *header)
> +{
> + handover_fn handover;
> + uintptr_t addr;
> +
> + addr = header->code32_start + header->handover_offset;
> + if (IS_ENABLED(CONFIG_X86_64))
> + addr += 512;
> +
> + handover = efi_phys_to_virt(addr);
> + handover(handle, efi_sys_table, header);
> +}
> +
> +static int do_bootm_efi(struct image_data *data)
> +{
> + void *tmp;
> + void *initrd = NULL;
> + size_t size;
> + efi_handle_t handle;
> + int ret;
> + const char *options;
> + struct efi_loaded_image *loaded_image;
> + struct x86_setup_header *image_header, *boot_header;
> +
> + ret = efi_load_image(data->os_file, &loaded_image, &handle);
> + if (ret)
> + return ret;
> +
> + image_header = (struct x86_setup_header *)loaded_image->image_base;
> +
> + if (!is_x86_setup_header(image_header) ||
> + image_header->version < 0x20b ||
> + !image_header->relocatable_kernel) {
> + pr_err("Not a valid kernel image!\n");
> + BS->unload_image(handle);
> + return -EINVAL;
> + }
> +
> + boot_header = xmalloc(0x4000);
> + memset(boot_header, 0, 0x4000);
> + memcpy(boot_header, image_header, sizeof(*image_header));
> +
> + /* Refer to Linux kernel commit a27e292b8a54
> + * ("Documentation/x86/boot: Reserve type_of_loader=13 for barebox")
> + */
> + boot_header->type_of_loader = 0x13;
> +
> + if (data->initrd_file) {
> + tmp = read_file(data->initrd_file, &size);
> + initrd = xmemalign(PAGE_SIZE, PAGE_ALIGN(size));
> + memcpy(initrd, tmp, size);
> + memset(initrd + size, 0, PAGE_ALIGN(size) - size);
> + free(tmp);
> + boot_header->ramdisk_image = efi_virt_to_phys(initrd);
> + boot_header->ramdisk_size = PAGE_ALIGN(size);
> + }
> +
> + options = linux_bootargs_get();
> + if (options) {
> + boot_header->cmd_line_ptr = efi_virt_to_phys(options);
> + boot_header->cmdline_size = strlen(options);
> + }
> +
> + boot_header->code32_start = efi_virt_to_phys(loaded_image->image_base +
> + (image_header->setup_sects+1) * 512);
> +
> + if (bootm_verbose(data)) {
> + printf("\nStarting kernel at 0x%p", loaded_image->image_base);
> + if (data->initrd_file)
> + printf(", initrd at 0x%08x",
> + boot_header->ramdisk_image);
> + printf("...\n");
> + }
> +
> + if (data->dryrun) {
> + BS->unload_image(handle);
> + free(boot_header);
> + free(initrd);
> + return 0;
> + }
> +
> + efi_set_variable_usec("LoaderTimeExecUSec", &efi_systemd_vendor_guid,
> + ktime_to_us(ktime_get()));
> +
> + shutdown_barebox();
> + linux_efi_handover(handle, boot_header);
> +
> + return 0;
> +}
> +
> +static struct image_handler efi_handle_tr = {
> + .name = "EFI Application",
> + .bootm = do_bootm_efi,
> + .filetype = filetype_exe,
> +};
> +
> +static int efi_register_handover_handler(void)
> +{
> + register_image_handler(&efi_handle_tr);
> + return 0;
> +}
> +late_efi_initcall(efi_register_handover_handler);
> diff --git a/efi/payload/image.c b/efi/payload/image.c
> index 33c5e18dac27..ae7678188d84 100644
> --- a/efi/payload/image.c
> +++ b/efi/payload/image.c
> @@ -5,13 +5,12 @@
> * Copyright (c) 2014 Sascha Hauer <[email protected]>, Pengutronix
> */
>
> +#define pr_fmt(fmt) "efi-image: " fmt
> +
> #include <clock.h>
> #include <common.h>
> #include <linux/sizes.h>
> -#include <linux/ktime.h>
> #include <memory.h>
> -#include <command.h>
> -#include <magicvar.h>
> #include <init.h>
> #include <driver.h>
> #include <io.h>
> @@ -19,7 +18,7 @@
> #include <malloc.h>
> #include <string.h>
> #include <linux/err.h>
> -#include <boot.h>
> +#include <bootargs.h>
> #include <bootm.h>
> #include <fs.h>
> #include <libfile.h>
> @@ -28,54 +27,8 @@
> #include <efi/efi-payload.h>
> #include <efi/efi-device.h>
>
> -struct linux_kernel_header {
> - /* first sector of the image */
> - uint8_t code1[0x0020];
> - uint16_t cl_magic; /**< Magic number 0xA33F */
> - uint16_t cl_offset; /**< The offset of command line */
> - uint8_t code2[0x01F1 - 0x0020 - 2 - 2];
> - uint8_t setup_sects; /**< The size of the setup in sectors */
> - uint16_t root_flags; /**< If the root is mounted readonly */
> - uint16_t syssize; /**< obsolete */
> - uint16_t swap_dev; /**< obsolete */
> - uint16_t ram_size; /**< obsolete */
> - uint16_t vid_mode; /**< Video mode control */
> - uint16_t root_dev; /**< Default root device number */
> - uint16_t boot_flag; /**< 0xAA55 magic number */
> -
> - /* second sector of the image */
> - uint16_t jump; /**< Jump instruction (this is code!) */
> - uint32_t header; /**< Magic signature "HdrS" */
> - uint16_t version; /**< Boot protocol version supported */
> - uint32_t realmode_swtch; /**< Boot loader hook */
> - uint16_t start_sys; /**< The load-low segment (obsolete) */
> - uint16_t kernel_version; /**< Points to kernel version string */
> - uint8_t type_of_loader; /**< Boot loader identifier */
> - uint8_t loadflags; /**< Boot protocol option flags */
> - uint16_t setup_move_size; /**< Move to high memory size */
> - uint32_t code32_start; /**< Boot loader hook */
> - uint32_t ramdisk_image; /**< initrd load address */
> - uint32_t ramdisk_size; /**< initrd size */
> - uint32_t bootsect_kludge; /**< obsolete */
> - uint16_t heap_end_ptr; /**< Free memory after setup end */
> - uint8_t ext_loader_ver; /**< boot loader's extension of the
> version number */
> - uint8_t ext_loader_type; /**< boot loader's extension of its
> type */
> - uint32_t cmd_line_ptr; /**< Points to the kernel command line
> */
> - uint32_t initrd_addr_max; /**< Highest address for initrd */
> - uint32_t kernel_alignment; /**< Alignment unit required by the
> kernel */
> - uint8_t relocatable_kernel; /** */
> - uint8_t min_alignment; /** */
> - uint16_t xloadflags; /** */
> - uint32_t cmdline_size; /** */
> - uint32_t hardware_subarch; /** */
> - uint64_t hardware_subarch_data; /** */
> - uint32_t payload_offset; /** */
> - uint32_t payload_length; /** */
> - uint64_t setup_data; /** */
> - uint64_t pref_address; /** */
> - uint32_t init_size; /** */
> - uint32_t handover_offset; /** */
> -} __attribute__ ((packed));
> +#include "image.h"
> +#include "setup_header.h"
>
> static void *efi_read_file(const char *file, size_t *size)
> {
> @@ -85,10 +38,6 @@ static void *efi_read_file(const char *file, size_t *size)
> char *buf;
> ssize_t ret;
>
> - buf = read_file(file, size);
> - if (buf || errno != ENOMEM)
> - return buf;
> -
> ret = stat(file, &s);
> if (ret)
> return NULL;
> @@ -122,8 +71,8 @@ static void efi_free_file(void *_mem, size_t size)
> BS->free_pages(mem, DIV_ROUND_UP(size, EFI_PAGE_SIZE));
> }
>
> -static int efi_load_image(const char *file, struct efi_loaded_image
> **loaded_image,
> - efi_handle_t *h)
> +int efi_load_image(const char *file, struct efi_loaded_image **loaded_image,
> + efi_handle_t *h)
> {
> void *exe;
> size_t size;
> @@ -158,10 +107,7 @@ static int efi_load_image(const char *file, struct
> efi_loaded_image **loaded_ima
>
> static bool is_linux_image(enum filetype filetype, const void *base)
> {
> - const struct linux_kernel_header *hdr = base;
> -
> - if (IS_ENABLED(CONFIG_X86) &&
> - hdr->boot_flag == 0xAA55 && hdr->header == 0x53726448)
> + if (IS_ENABLED(CONFIG_X86) && is_x86_setup_header(base))
> return true;
>
> if (IS_ENABLED(CONFIG_ARM64) &&
> @@ -171,18 +117,13 @@ static bool is_linux_image(enum filetype filetype,
> const void *base)
> return false;
> }
>
> -static int efi_execute_image(enum filetype filetype, const char *file)
> +int efi_execute_image(efi_handle_t handle,
> + struct efi_loaded_image *loaded_image,
> + enum filetype filetype)
> {
> - efi_handle_t handle;
> - struct efi_loaded_image *loaded_image;
> efi_status_t efiret;
> const char *options;
> bool is_driver;
> - int ret;
> -
> - ret = efi_load_image(file, &loaded_image, &handle);
> - if (ret)
> - return ret;
>
> is_driver = (loaded_image->image_code_type == EFI_BOOT_SERVICES_CODE) ||
> (loaded_image->image_code_type == EFI_RUNTIME_SERVICES_CODE);
> @@ -216,110 +157,17 @@ static int efi_execute_image(enum filetype filetype,
> const char *file)
> return -efi_errno(efiret);
> }
>
> -typedef void(*handover_fn)(void *image, struct efi_system_table *table,
> - struct linux_kernel_header *header);
> -
> -static inline void linux_efi_handover(efi_handle_t handle,
> - struct linux_kernel_header *header)
> -{
> - handover_fn handover;
> - uintptr_t addr;
> -
> - addr = header->code32_start + header->handover_offset;
> - if (IS_ENABLED(CONFIG_X86_64))
> - addr += 512;
> -
> - handover = efi_phys_to_virt(addr);
> - handover(handle, efi_sys_table, header);
> -}
> -
> -static int do_bootm_efi(struct image_data *data)
> +static int efi_execute(struct binfmt_hook *b, char *file, int argc, char
> **argv)
> {
> - void *tmp;
> - void *initrd = NULL;
> - size_t size;
> + struct efi_loaded_image *loaded_image;
> efi_handle_t handle;
> int ret;
> - const char *options;
> - struct efi_loaded_image *loaded_image;
> - struct linux_kernel_header *image_header, *boot_header;
>
> - ret = efi_load_image(data->os_file, &loaded_image, &handle);
> + ret = efi_load_image(file, &loaded_image, &handle);
> if (ret)
> return ret;
>
> - image_header = (struct linux_kernel_header *)loaded_image->image_base;
> -
> - if (image_header->boot_flag != 0xAA55 ||
> - image_header->header != 0x53726448 ||
> - image_header->version < 0x20b ||
> - !image_header->relocatable_kernel) {
> - pr_err("Not a valid kernel image!\n");
> - BS->unload_image(handle);
> - return -EINVAL;
> - }
> -
> - boot_header = xmalloc(0x4000);
> - memset(boot_header, 0, 0x4000);
> - memcpy(boot_header, image_header, sizeof(*image_header));
> -
> - /* Refer to Linux kernel commit a27e292b8a54
> - * ("Documentation/x86/boot: Reserve type_of_loader=13 for barebox")
> - */
> - boot_header->type_of_loader = 0x13;
> -
> - if (data->initrd_file) {
> - tmp = read_file(data->initrd_file, &size);
> - initrd = xmemalign(PAGE_SIZE, PAGE_ALIGN(size));
> - memcpy(initrd, tmp, size);
> - memset(initrd + size, 0, PAGE_ALIGN(size) - size);
> - free(tmp);
> - boot_header->ramdisk_image = efi_virt_to_phys(initrd);
> - boot_header->ramdisk_size = PAGE_ALIGN(size);
> - }
> -
> - options = linux_bootargs_get();
> - if (options) {
> - boot_header->cmd_line_ptr = efi_virt_to_phys(options);
> - boot_header->cmdline_size = strlen(options);
> - }
> -
> - boot_header->code32_start = efi_virt_to_phys(loaded_image->image_base +
> - (image_header->setup_sects+1) * 512);
> -
> - if (bootm_verbose(data)) {
> - printf("\nStarting kernel at 0x%p", loaded_image->image_base);
> - if (data->initrd_file)
> - printf(", initrd at 0x%08x",
> - boot_header->ramdisk_image);
> - printf("...\n");
> - }
> -
> - if (data->dryrun) {
> - BS->unload_image(handle);
> - free(boot_header);
> - free(initrd);
> - return 0;
> - }
> -
> - efi_set_variable_usec("LoaderTimeExecUSec", &efi_systemd_vendor_guid,
> - ktime_to_us(ktime_get()));
> -
> - shutdown_barebox();
> - linux_efi_handover(handle, boot_header);
> -
> - return 0;
> -}
> -
> -static struct image_handler efi_handle_tr = {
> - .name = "EFI Application",
> - .bootm = do_bootm_efi,
> - .filetype = filetype_exe,
> -};
> -
> -static int efi_execute(struct binfmt_hook *b, char *file, int argc, char
> **argv)
> -{
> - return efi_execute_image(b->type, file);
> + return efi_execute_image(handle, loaded_image, b->type);
> }
>
> static struct binfmt_hook binfmt_efi_hook = {
> @@ -352,13 +200,19 @@ static struct binfmt_hook binfmt_arm64_efi_hook = {
> .hook = efi_execute,
> };
>
> +static struct binfmt_hook binfmt_x86_efi_hook = {
> + .type = filetype_x86_linux_image,
> + .hook = efi_execute,
> +};
> +
> static int efi_register_image_handler(void)
> {
> - register_image_handler(&efi_handle_tr);
> binfmt_register(&binfmt_efi_hook);
>
> - if (IS_ENABLED(CONFIG_X86))
> + if (IS_ENABLED(CONFIG_X86)) {
> register_image_handler(&non_efi_handle_linux_x86);
> + binfmt_register(&binfmt_x86_efi_hook);
> + }
>
> if (IS_ENABLED(CONFIG_ARM64))
> binfmt_register(&binfmt_arm64_efi_hook);
> diff --git a/efi/payload/image.h b/efi/payload/image.h
> new file mode 100644
> index 000000000000..673b21db839a
> --- /dev/null
> +++ b/efi/payload/image.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef __EFI_PAYLOAD_IMAGE_H__
> +#define __EFI_PAYLOAD_IMAGE_H__
> +
> +#include <efi/types.h>
> +
> +int efi_load_image(const char *file, struct efi_loaded_image **loaded_image,
> + efi_handle_t *h);
> +
> +int efi_execute_image(efi_handle_t handle,
> + struct efi_loaded_image *loaded_image,
> + enum filetype filetype);
> +
> +#endif
> diff --git a/efi/payload/setup_header.h b/efi/payload/setup_header.h
> new file mode 100644
> index 000000000000..4f094b844415
> --- /dev/null
> +++ b/efi/payload/setup_header.h
> @@ -0,0 +1,63 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef __EFI_PAYLOAD_SETUP_HEADER_H__
> +#define __EFI_PAYLOAD_SETUP_HEADER_H__
> +
> +#include <linux/types.h>
> +
> +struct x86_setup_header {
> + /* first sector of the image */
> + uint8_t code1[0x0020];
> + uint16_t cl_magic; /**< Magic number 0xA33F */
> + uint16_t cl_offset; /**< The offset of command line */
> + uint8_t code2[0x01F1 - 0x0020 - 2 - 2];
> + uint8_t setup_sects; /**< The size of the setup in sectors */
> + uint16_t root_flags; /**< If the root is mounted readonly */
> + uint16_t syssize; /**< obsolete */
> + uint16_t swap_dev; /**< obsolete */
> + uint16_t ram_size; /**< obsolete */
> + uint16_t vid_mode; /**< Video mode control */
> + uint16_t root_dev; /**< Default root device number */
> + uint16_t boot_flag; /**< 0xAA55 magic number */
> +
> + /* second sector of the image */
> + uint16_t jump; /**< Jump instruction (this is code!) */
> + uint32_t header; /**< Magic signature "HdrS" */
> + uint16_t version; /**< Boot protocol version supported */
> + uint32_t realmode_swtch; /**< Boot loader hook */
> + uint16_t start_sys; /**< The load-low segment (obsolete) */
> + uint16_t kernel_version; /**< Points to kernel version string */
> + uint8_t type_of_loader; /**< Boot loader identifier */
> + uint8_t loadflags; /**< Boot protocol option flags */
> + uint16_t setup_move_size; /**< Move to high memory size */
> + uint32_t code32_start; /**< Boot loader hook */
> + uint32_t ramdisk_image; /**< initrd load address */
> + uint32_t ramdisk_size; /**< initrd size */
> + uint32_t bootsect_kludge; /**< obsolete */
> + uint16_t heap_end_ptr; /**< Free memory after setup end */
> + uint8_t ext_loader_ver; /**< boot loader's extension of the
> version number */
> + uint8_t ext_loader_type; /**< boot loader's extension of its
> type */
> + uint32_t cmd_line_ptr; /**< Points to the kernel command line
> */
> + uint32_t initrd_addr_max; /**< Highest address for initrd */
> + uint32_t kernel_alignment; /**< Alignment unit required by the
> kernel */
> + uint8_t relocatable_kernel; /** */
> + uint8_t min_alignment; /** */
> + uint16_t xloadflags; /** */
> + uint32_t cmdline_size; /** */
> + uint32_t hardware_subarch; /** */
> + uint64_t hardware_subarch_data; /** */
> + uint32_t payload_offset; /** */
> + uint32_t payload_length; /** */
> + uint64_t setup_data; /** */
> + uint64_t pref_address; /** */
> + uint32_t init_size; /** */
> + uint32_t handover_offset; /** */
> +} __attribute__ ((packed));
> +
> +static inline bool is_x86_setup_header(const void *base)
> +{
> + const struct x86_setup_header *hdr = base;
> +
> + return hdr->boot_flag == 0xAA55 && hdr->header == 0x53726448;
> +}
> +
> +#endif
--
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