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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Generic Linux boot protocol using the EFI/PE entry point of the kernel. Passes
* initrd with the LINUX_INITRD_MEDIA_GUID DevicePath and cmdline with
* EFI LoadedImageProtocol.
*
* This method works for Linux 5.8 and newer on ARM/Aarch64, x86/x68_64 and RISC-V.
*/
#include "efi-log.h"
#include "initrd.h"
#include "linux.h"
#include "pe.h"
#include "proto/device-path.h"
#include "proto/loaded-image.h"
#include "util.h"
typedef struct {
MEMMAP_DEVICE_PATH memmap_path;
EFI_DEVICE_PATH end_path;
} _packed_ KERNEL_FILE_PATH;
EFI_STATUS linux_exec(
EFI_HANDLE parent_image,
const char16_t *cmdline,
const struct iovec *kernel,
const struct iovec *initrd) {
EFI_LOADED_IMAGE_PROTOCOL original_parent_loaded_image;
size_t kernel_size_in_memory = 0;
uint32_t entry_point;
uint64_t image_base;
EFI_STATUS err;
assert(parent_image);
assert(iovec_is_set(kernel));
assert(iovec_is_valid(initrd));
err = pe_kernel_info(kernel->iov_base, &entry_point, &image_base, &kernel_size_in_memory);
if (err != EFI_SUCCESS)
return log_error_status(err, "Bad kernel image: %m");
/* Re-use the parent_image(_handle) and parent_loaded_image for the kernel image we are about to execute.
* We have to do this, because if kernel stub code passes its own handle to certain firmware functions,
* the firmware could cast EFI_LOADED_IMAGE_PROTOCOL * to a larger struct to access its own private data,
* and if we allocated a smaller struct, that could cause problems.
* This is modeled exactly after GRUB behaviour, which has proven to be functional. */
EFI_LOADED_IMAGE_PROTOCOL* parent_loaded_image;
err = BS->HandleProtocol(
parent_image, MAKE_GUID_PTR(EFI_LOADED_IMAGE_PROTOCOL), (void **) &parent_loaded_image);
if (err != EFI_SUCCESS)
return log_error_status(err, "Cannot get parent loaded image: %m");
err = pe_kernel_check_no_relocation(kernel->iov_base);
if (err != EFI_SUCCESS)
return err;
const PeSectionHeader *headers;
size_t n_headers;
/* Do we need to validate anything here? the len? */
err = pe_section_table_from_base(kernel->iov_base, &headers, &n_headers);
if (err != EFI_SUCCESS)
return log_error_status(err, "Cannot read sections: %m");
/* Do we need to ensure under 4gb address on x86? */
_cleanup_pages_ Pages loaded_kernel_pages = xmalloc_pages(
AllocateAnyPages, EfiLoaderCode, EFI_SIZE_TO_PAGES(kernel_size_in_memory), 0);
uint8_t* loaded_kernel = PHYSICAL_ADDRESS_TO_POINTER(loaded_kernel_pages.addr);
FOREACH_ARRAY(h, headers, n_headers) {
if (h->PointerToRelocations != 0)
return log_error_status(EFI_LOAD_ERROR, "Inner kernel image contains sections with relocations, which we do not support.");
if (h->SizeOfRawData == 0)
continue;
if ((h->VirtualAddress < image_base)
|| (h->VirtualAddress - image_base + h->SizeOfRawData > kernel_size_in_memory))
return log_error_status(EFI_LOAD_ERROR, "Section would write outside of memory");
memcpy(loaded_kernel + h->VirtualAddress - image_base,
(const uint8_t*)kernel->iov_base + h->PointerToRawData,
h->SizeOfRawData);
memzero(loaded_kernel + h->VirtualAddress + h->SizeOfRawData,
h->VirtualSize - h->SizeOfRawData);
}
_cleanup_free_ KERNEL_FILE_PATH *kernel_file_path = xnew(KERNEL_FILE_PATH, 1);
kernel_file_path->memmap_path.Header.Type = HARDWARE_DEVICE_PATH;
kernel_file_path->memmap_path.Header.SubType = HW_MEMMAP_DP;
kernel_file_path->memmap_path.Header.Length = sizeof (MEMMAP_DEVICE_PATH);
kernel_file_path->memmap_path.MemoryType = EfiLoaderData;
kernel_file_path->memmap_path.StartingAddress = POINTER_TO_PHYSICAL_ADDRESS(kernel->iov_base);
kernel_file_path->memmap_path.EndingAddress = POINTER_TO_PHYSICAL_ADDRESS(kernel->iov_base) + kernel->iov_len;
kernel_file_path->end_path.Type = END_DEVICE_PATH_TYPE;
kernel_file_path->end_path.SubType = END_ENTIRE_DEVICE_PATH_SUBTYPE;
kernel_file_path->end_path.Length = sizeof (EFI_DEVICE_PATH);
original_parent_loaded_image = *parent_loaded_image;
parent_loaded_image->FilePath = &kernel_file_path->memmap_path.Header;
parent_loaded_image->ImageBase = loaded_kernel;
parent_loaded_image->ImageSize = kernel_size_in_memory;
if (cmdline) {
parent_loaded_image->LoadOptions = (void *) cmdline;
parent_loaded_image->LoadOptionsSize = strsize16(parent_loaded_image->LoadOptions);
}
_cleanup_(cleanup_initrd) EFI_HANDLE initrd_handle = NULL;
err = initrd_register(initrd->iov_base, initrd->iov_len, &initrd_handle);
if (err != EFI_SUCCESS)
return log_error_status(err, "Error registering initrd: %m");
log_wait();
EFI_IMAGE_ENTRY_POINT entry =
(EFI_IMAGE_ENTRY_POINT) ((const uint8_t *) parent_loaded_image->ImageBase + entry_point);
err = entry(parent_image, ST);
/* Restore */
*parent_loaded_image = original_parent_loaded_image;
return log_error_status(err, "Error starting kernel image: %m");
}
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