linux/drivers/firmware/efi/libstub/file.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Helper functions used by the EFI stub on multiple
 * architectures. This should be #included by the EFI stub
 * implementation files.
 *
 * Copyright 2011 Intel Corporation; author Matt Fleming
 */

#include <linux/efi.h>
#include <asm/efi.h>

#include "efistub.h"

#define MAX_FILENAME_SIZE …

/*
 * Some firmware implementations have problems reading files in one go.
 * A read chunk size of 1MB seems to work for most platforms.
 *
 * Unfortunately, reading files in chunks triggers *other* bugs on some
 * platforms, so we provide a way to disable this workaround, which can
 * be done by passing "efi=nochunk" on the EFI boot stub command line.
 *
 * If you experience issues with initrd images being corrupt it's worth
 * trying efi=nochunk, but chunking is enabled by default on x86 because
 * there are far more machines that require the workaround than those that
 * break with it enabled.
 */
#define EFI_READ_CHUNK_SIZE …

struct finfo { … };

static efi_status_t efi_open_file(efi_file_protocol_t *volume,
				  struct finfo *fi,
				  efi_file_protocol_t **handle,
				  unsigned long *file_size)
{ … }

static efi_status_t efi_open_volume(efi_loaded_image_t *image,
				    efi_file_protocol_t **fh)
{ … }

static int find_file_option(const efi_char16_t *cmdline, int cmdline_len,
			    const efi_char16_t *prefix, int prefix_size,
			    efi_char16_t *result, int result_len)
{ … }

static efi_status_t efi_open_device_path(efi_file_protocol_t **volume,
					 struct finfo *fi)
{ … }

/*
 * Check the cmdline for a LILO-style file= arguments.
 *
 * We only support loading a file from the same filesystem as
 * the kernel image.
 */
efi_status_t handle_cmdline_files(efi_loaded_image_t *image,
				  const efi_char16_t *optstr,
				  int optstr_size,
				  unsigned long soft_limit,
				  unsigned long hard_limit,
				  unsigned long *load_addr,
				  unsigned long *load_size)
{ … }