1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2013, 2014 Linaro Ltd; <roy.franz@linaro.org>
5 * This file implements the EFI boot stub for the arm64 kernel.
6 * Adapted from ARM version by Mark Salter <msalter@redhat.com>
10 #include <linux/efi.h>
12 #include <asm/memory.h>
13 #include <asm/sections.h>
18 * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail
19 * to provide space, and fail to zero it). Check for this condition by double
20 * checking that the first and the last byte of the image are covered by the
21 * same EFI memory map entry.
23 static bool check_image_region(u64 base, u64 size)
25 struct efi_boot_memmap *map;
30 status = efi_get_memory_map(&map, false);
31 if (status != EFI_SUCCESS)
34 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
35 efi_memory_desc_t *md = (void *)map->map + map_offset;
36 u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE;
39 * Find the region that covers base, and return whether
40 * it covers base+size bytes.
42 if (base >= md->phys_addr && base < end) {
43 ret = (base + size) <= end;
48 efi_bs_call(free_pool, map);
53 efi_status_t handle_kernel_image(unsigned long *image_addr,
54 unsigned long *image_size,
55 unsigned long *reserve_addr,
56 unsigned long *reserve_size,
57 efi_loaded_image_t *image,
58 efi_handle_t image_handle)
61 unsigned long kernel_size, kernel_codesize, kernel_memsize;
63 u64 min_kimg_align = efi_get_kimg_min_align();
65 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
66 efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID;
70 efi_info("KASLR disabled on kernel command line\n");
71 } else if (efi_bs_call(handle_protocol, image_handle,
72 &li_fixed_proto, &p) == EFI_SUCCESS) {
73 efi_info("Image placement fixed by loader\n");
75 status = efi_get_random_bytes(sizeof(phys_seed),
77 if (status == EFI_NOT_FOUND) {
78 efi_info("EFI_RNG_PROTOCOL unavailable\n");
80 } else if (status != EFI_SUCCESS) {
81 efi_err("efi_get_random_bytes() failed (0x%lx)\n",
88 if (image->image_base != _text) {
89 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
90 image->image_base = _text;
93 if (!IS_ALIGNED((u64)_text, SEGMENT_ALIGN))
94 efi_err("FIRMWARE BUG: kernel image not aligned on %dk boundary\n",
97 kernel_size = _edata - _text;
98 kernel_codesize = __inittext_end - _text;
99 kernel_memsize = kernel_size + (_end - _edata);
100 *reserve_size = kernel_memsize;
102 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
104 * If KASLR is enabled, and we have some randomness available,
105 * locate the kernel at a randomized offset in physical memory.
107 status = efi_random_alloc(*reserve_size, min_kimg_align,
108 reserve_addr, phys_seed,
109 EFI_LOADER_CODE, EFI_ALLOC_LIMIT);
110 if (status != EFI_SUCCESS)
111 efi_warn("efi_random_alloc() failed: 0x%lx\n", status);
113 status = EFI_OUT_OF_RESOURCES;
116 if (status != EFI_SUCCESS) {
117 if (!check_image_region((u64)_text, kernel_memsize)) {
118 efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n");
119 } else if (IS_ALIGNED((u64)_text, min_kimg_align) &&
120 (u64)_end < EFI_ALLOC_LIMIT) {
122 * Just execute from wherever we were loaded by the
123 * UEFI PE/COFF loader if the placement is suitable.
125 *image_addr = (u64)_text;
130 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
131 ULONG_MAX, min_kimg_align,
134 if (status != EFI_SUCCESS) {
135 efi_err("Failed to relocate kernel\n");
141 *image_addr = *reserve_addr;
142 memcpy((void *)*image_addr, _text, kernel_size);
143 caches_clean_inval_pou(*image_addr, *image_addr + kernel_codesize);
144 efi_remap_image(*image_addr, *reserve_size, kernel_codesize);
149 asmlinkage void primary_entry(void);
151 unsigned long primary_entry_offset(void)
154 * When built as part of the kernel, the EFI stub cannot branch to the
155 * kernel proper via the image header, as the PE/COFF header is
156 * strictly not part of the in-memory presentation of the image, only
157 * of the file representation. So instead, we need to jump to the
158 * actual entrypoint in the .text region of the image.
160 return (char *)primary_entry - _text;