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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <efi.h>
#include <efilib.h>
#include "linux.h"
#include "util.h"
#define SETUP_MAGIC 0x53726448 /* "HdrS" */
struct SetupHeader {
UINT8 boot_sector[0x01f1];
UINT8 setup_secs;
UINT16 root_flags;
UINT32 sys_size;
UINT16 ram_size;
UINT16 video_mode;
UINT16 root_dev;
UINT16 signature;
UINT16 jump;
UINT32 header;
UINT16 version;
UINT16 su_switch;
UINT16 setup_seg;
UINT16 start_sys;
UINT16 kernel_ver;
UINT8 loader_id;
UINT8 load_flags;
UINT16 movesize;
UINT32 code32_start;
UINT32 ramdisk_start;
UINT32 ramdisk_len;
UINT32 bootsect_kludge;
UINT16 heap_end;
UINT8 ext_loader_ver;
UINT8 ext_loader_type;
UINT32 cmd_line_ptr;
UINT32 ramdisk_max;
UINT32 kernel_alignment;
UINT8 relocatable_kernel;
UINT8 min_alignment;
UINT16 xloadflags;
UINT32 cmdline_size;
UINT32 hardware_subarch;
UINT64 hardware_subarch_data;
UINT32 payload_offset;
UINT32 payload_length;
UINT64 setup_data;
UINT64 pref_address;
UINT32 init_size;
UINT32 handover_offset;
} __attribute__((packed));
#ifdef __x86_64__
typedef VOID(*handover_f)(VOID *image, EFI_SYSTEM_TABLE *table, struct SetupHeader *setup);
static VOID linux_efi_handover(EFI_HANDLE image, struct SetupHeader *setup) {
handover_f handover;
asm volatile ("cli");
handover = (handover_f)((UINTN)setup->code32_start + 512 + setup->handover_offset);
handover(image, ST, setup);
}
#else
typedef VOID(*handover_f)(VOID *image, EFI_SYSTEM_TABLE *table, struct SetupHeader *setup) __attribute__((regparm(0)));
static VOID linux_efi_handover(EFI_HANDLE image, struct SetupHeader *setup) {
handover_f handover;
handover = (handover_f)((UINTN)setup->code32_start + setup->handover_offset);
handover(image, ST, setup);
}
#endif
EFI_STATUS linux_exec(EFI_HANDLE *image,
CHAR8 *cmdline, UINTN cmdline_len,
UINTN linux_addr,
UINTN initrd_addr, UINTN initrd_size, BOOLEAN secure) {
struct SetupHeader *image_setup;
struct SetupHeader *boot_setup;
EFI_PHYSICAL_ADDRESS addr;
EFI_STATUS err;
image_setup = (struct SetupHeader *)(linux_addr);
if (image_setup->signature != 0xAA55 || image_setup->header != SETUP_MAGIC)
return EFI_LOAD_ERROR;
if (image_setup->version < 0x20b || !image_setup->relocatable_kernel)
return EFI_LOAD_ERROR;
addr = 0x3fffffff;
err = uefi_call_wrapper(BS->AllocatePages, 4, AllocateMaxAddress, EfiLoaderData,
EFI_SIZE_TO_PAGES(0x4000), &addr);
if (EFI_ERROR(err))
return err;
boot_setup = (struct SetupHeader *)(UINTN)addr;
ZeroMem(boot_setup, 0x4000);
CopyMem(boot_setup, image_setup, sizeof(struct SetupHeader));
boot_setup->loader_id = 0xff;
if (secure) {
/* set secure boot flag in linux kernel zero page, see
- Documentation/x86/zero-page.txt
- arch/x86/include/uapi/asm/bootparam.h
- drivers/firmware/efi/libstub/secureboot.c
in the linux kernel source tree
Possible values: 0 (unassigned), 1 (undetected), 2 (disabled), 3 (enabled)
*/
boot_setup->boot_sector[0x1ec] = 3;
}
boot_setup->code32_start = (UINT32)linux_addr + (image_setup->setup_secs+1) * 512;
if (cmdline) {
addr = 0xA0000;
err = uefi_call_wrapper(BS->AllocatePages, 4, AllocateMaxAddress, EfiLoaderData,
EFI_SIZE_TO_PAGES(cmdline_len + 1), &addr);
if (EFI_ERROR(err))
return err;
CopyMem((VOID *)(UINTN)addr, cmdline, cmdline_len);
((CHAR8 *)(UINTN)addr)[cmdline_len] = 0;
boot_setup->cmd_line_ptr = (UINT32)addr;
}
boot_setup->ramdisk_start = (UINT32)initrd_addr;
boot_setup->ramdisk_len = (UINT32)initrd_size;
linux_efi_handover(image, boot_setup);
return EFI_LOAD_ERROR;
}
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