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>
14 #include <asm/sysreg.h>
18 efi_status_t check_platform_features(void)
22 /* UEFI mandates support for 4 KB granularity, no need to check */
23 if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
26 tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf;
27 if (tg < ID_AA64MMFR0_TGRAN_SUPPORTED_MIN || tg > ID_AA64MMFR0_TGRAN_SUPPORTED_MAX) {
28 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
29 efi_err("This 64 KB granular kernel is not supported by your CPU\n");
31 efi_err("This 16 KB granular kernel is not supported by your CPU\n");
32 return EFI_UNSUPPORTED;
38 * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail
39 * to provide space, and fail to zero it). Check for this condition by double
40 * checking that the first and the last byte of the image are covered by the
41 * same EFI memory map entry.
43 static bool check_image_region(u64 base, u64 size)
45 unsigned long map_size, desc_size, buff_size;
46 efi_memory_desc_t *memory_map;
47 struct efi_boot_memmap map;
52 map.map = &memory_map;
53 map.map_size = &map_size;
54 map.desc_size = &desc_size;
57 map.buff_size = &buff_size;
59 status = efi_get_memory_map(&map);
60 if (status != EFI_SUCCESS)
63 for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
64 efi_memory_desc_t *md = (void *)memory_map + map_offset;
65 u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE;
68 * Find the region that covers base, and return whether
69 * it covers base+size bytes.
71 if (base >= md->phys_addr && base < end) {
72 ret = (base + size) <= end;
77 efi_bs_call(free_pool, memory_map);
82 efi_status_t handle_kernel_image(unsigned long *image_addr,
83 unsigned long *image_size,
84 unsigned long *reserve_addr,
85 unsigned long *reserve_size,
86 efi_loaded_image_t *image,
87 efi_handle_t image_handle)
90 unsigned long kernel_size, kernel_memsize = 0;
94 * Although relocatable kernels can fix up the misalignment with
95 * respect to MIN_KIMG_ALIGN, the resulting virtual text addresses are
96 * subtly out of sync with those recorded in the vmlinux when kaslr is
97 * disabled but the image required relocation anyway. Therefore retain
98 * 2M alignment if KASLR was explicitly disabled, even if it was not
99 * going to be activated to begin with.
101 u64 min_kimg_align = efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
103 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
104 efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID;
108 efi_info("KASLR disabled on kernel command line\n");
109 } else if (efi_bs_call(handle_protocol, image_handle,
110 &li_fixed_proto, &p) == EFI_SUCCESS) {
111 efi_info("Image placement fixed by loader\n");
113 status = efi_get_random_bytes(sizeof(phys_seed),
115 if (status == EFI_NOT_FOUND) {
116 efi_info("EFI_RNG_PROTOCOL unavailable\n");
118 } else if (status != EFI_SUCCESS) {
119 efi_err("efi_get_random_bytes() failed (0x%lx)\n",
126 if (image->image_base != _text)
127 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
129 if (!IS_ALIGNED((u64)_text, SEGMENT_ALIGN))
130 efi_err("FIRMWARE BUG: kernel image not aligned on %dk boundary\n",
131 SEGMENT_ALIGN >> 10);
133 kernel_size = _edata - _text;
134 kernel_memsize = kernel_size + (_end - _edata);
135 *reserve_size = kernel_memsize;
137 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
139 * If KASLR is enabled, and we have some randomness available,
140 * locate the kernel at a randomized offset in physical memory.
142 status = efi_random_alloc(*reserve_size, min_kimg_align,
143 reserve_addr, phys_seed);
144 if (status != EFI_SUCCESS)
145 efi_warn("efi_random_alloc() failed: 0x%lx\n", status);
147 status = EFI_OUT_OF_RESOURCES;
150 if (status != EFI_SUCCESS) {
151 if (!check_image_region((u64)_text, kernel_memsize)) {
152 efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n");
153 } else if (IS_ALIGNED((u64)_text, min_kimg_align)) {
155 * Just execute from wherever we were loaded by the
156 * UEFI PE/COFF loader if the alignment is suitable.
158 *image_addr = (u64)_text;
163 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
164 ULONG_MAX, min_kimg_align);
166 if (status != EFI_SUCCESS) {
167 efi_err("Failed to relocate kernel\n");
173 *image_addr = *reserve_addr;
174 memcpy((void *)*image_addr, _text, kernel_size);