linux.c

/*
 * stubby
 *
 * Copyright (c) 2020 Cisco Systems, Inc. <pmoore2@cisco.com>
 *
 * This file was originally copied from systemd under the LGPL-2.1+ license
 * and that license has been preserved in this project.  The systemd source
 * repository can be found at https://github.com/systemd/systemd.
 *
 */

/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 */

#include "stubby_efi.h"

#include "linux.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;

#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,
		      CHAR8 *cmdline, UINTN cmdline_len,
		      UINTN linux_addr,
		      UINTN initrd_addr, UINTN initrd_size)
{
	struct boot_params *image_params;
	struct boot_params *boot_params;
	UINT8 setup_sectors;
	EFI_PHYSICAL_ADDRESS addr;
	EFI_STATUS err;

	image_params = (struct boot_params *) linux_addr;

	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;

	boot_params = (struct boot_params *) 0xFFFFFFFF;
	err = uefi_call_wrapper(BS->AllocatePages, 4,
				AllocateMaxAddress,
				EfiLoaderData,
				EFI_SIZE_TO_PAGES(0x4000),
				(EFI_PHYSICAL_ADDRESS *) &boot_params);
	if (EFI_ERROR(err))
		return err;

	ZeroMem(boot_params, 0x4000);
	CopyMem(&boot_params->hdr, &image_params->hdr,
		sizeof(struct setup_header));
	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)linux_addr + \
					(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((VOID *)(UINTN)addr, cmdline, cmdline_len);
		((CHAR8 *)(UINTN)addr)[cmdline_len] = 0;
		boot_params->hdr.cmd_line_ptr = (UINT32)addr;
	}

	boot_params->hdr.ramdisk_image = (UINT32)initrd_addr;
	boot_params->hdr.ramdisk_size = (UINT32)initrd_size;

	linux_efi_handover(image, boot_params);
	return EFI_LOAD_ERROR;
}