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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <efi.h>
#include <efilib.h>
#include "linux.h"
#include "initrd.h"
#include "util.h"
#ifdef __i386__
#define __regparm0__ __attribute__((regparm(0)))
#else
#define __regparm0__
#endif
typedef VOID(*handover_f)(VOID *image, EFI_SYSTEM_TABLE *table, struct boot_params *params) __regparm0__;
static VOID linux_efi_handover(EFI_HANDLE image, struct boot_params *params) {
handover_f handover;
UINTN start = (UINTN)params->hdr.code32_start;
assert(params);
#ifdef __x86_64__
asm volatile ("cli");
start += 512;
#endif
handover = (handover_f)(start + params->hdr.handover_offset);
handover(image, ST, params);
}
EFI_STATUS linux_exec(
EFI_HANDLE image,
const CHAR8 *cmdline, UINTN cmdline_len,
const VOID *linux_buffer,
const VOID *initrd_buffer, UINTN initrd_length) {
const struct boot_params *image_params;
struct boot_params *boot_params;
EFI_HANDLE initrd_handle = NULL;
EFI_PHYSICAL_ADDRESS addr;
UINT8 setup_sectors;
EFI_STATUS err;
assert(image);
assert(cmdline || cmdline_len == 0);
assert(linux_buffer);
assert(initrd_buffer || initrd_length == 0);
image_params = (const struct boot_params *) linux_buffer;
if (image_params->hdr.boot_flag != 0xAA55 ||
image_params->hdr.header != SETUP_MAGIC ||
image_params->hdr.version < 0x20b ||
!image_params->hdr.relocatable_kernel)
return EFI_LOAD_ERROR;
addr = UINT32_MAX; /* Below the 32bit boundary */
err = uefi_call_wrapper(
BS->AllocatePages, 4,
AllocateMaxAddress,
EfiLoaderData,
EFI_SIZE_TO_PAGES(0x4000),
&addr);
if (EFI_ERROR(err))
return err;
boot_params = (struct boot_params *) PHYSICAL_ADDRESS_TO_POINTER(addr);
ZeroMem(boot_params, 0x4000);
boot_params->hdr = image_params->hdr;
boot_params->hdr.type_of_loader = 0xff;
setup_sectors = image_params->hdr.setup_sects > 0 ? image_params->hdr.setup_sects : 4;
boot_params->hdr.code32_start = (UINT32) POINTER_TO_PHYSICAL_ADDRESS(linux_buffer) + (setup_sectors + 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(PHYSICAL_ADDRESS_TO_POINTER(addr), cmdline, cmdline_len);
((CHAR8 *) PHYSICAL_ADDRESS_TO_POINTER(addr))[cmdline_len] = 0;
boot_params->hdr.cmd_line_ptr = (UINT32) addr;
}
/* Providing the initrd via LINUX_INITRD_MEDIA_GUID is only supported by Linux 5.8+ (5.7+ on ARM64).
Until supported kernels become more established, we continue to set ramdisk in the handover struct.
This value is overridden by kernels that support LINUX_INITRD_MEDIA_GUID.
If you need to know which protocol was used by the kernel, pass "efi=debug" to the kernel,
this will print a line when InitrdMediaGuid was successfully used to load the initrd.
*/
boot_params->hdr.ramdisk_image = (UINT32) POINTER_TO_PHYSICAL_ADDRESS(initrd_buffer);
boot_params->hdr.ramdisk_size = (UINT32) initrd_length;
/* register LINUX_INITRD_MEDIA_GUID */
err = initrd_register(initrd_buffer, initrd_length, &initrd_handle);
if (EFI_ERROR(err))
return err;
linux_efi_handover(image, boot_params);
(void) initrd_unregister(initrd_handle);
initrd_handle = NULL;
return EFI_LOAD_ERROR;
}
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