1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2013, 2014 Linaro Ltd; <roy.franz@linaro.org>
4 *
5 * This file implements the EFI boot stub for the arm64 kernel.
6 * Adapted from ARM version by Mark Salter <msalter@redhat.com>
7 */
8
9
10 #include <linux/efi.h>
11 #include <asm/efi.h>
12 #include <asm/memory.h>
13 #include <asm/sections.h>
14 #include <asm/sysreg.h>
15
16 #include "efistub.h"
17
check_platform_features(void)18 efi_status_t check_platform_features(void)
19 {
20 u64 tg;
21
22 /* UEFI mandates support for 4 KB granularity, no need to check */
23 if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
24 return EFI_SUCCESS;
25
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");
30 else
31 efi_err("This 16 KB granular kernel is not supported by your CPU\n");
32 return EFI_UNSUPPORTED;
33 }
34 return EFI_SUCCESS;
35 }
36
37 /*
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.
42 */
check_image_region(u64 base,u64 size)43 static bool check_image_region(u64 base, u64 size)
44 {
45 unsigned long map_size, desc_size, buff_size;
46 efi_memory_desc_t *memory_map;
47 struct efi_boot_memmap map;
48 efi_status_t status;
49 bool ret = false;
50 int map_offset;
51
52 map.map = &memory_map;
53 map.map_size = &map_size;
54 map.desc_size = &desc_size;
55 map.desc_ver = NULL;
56 map.key_ptr = NULL;
57 map.buff_size = &buff_size;
58
59 status = efi_get_memory_map(&map);
60 if (status != EFI_SUCCESS)
61 return false;
62
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;
66
67 /*
68 * Find the region that covers base, and return whether
69 * it covers base+size bytes.
70 */
71 if (base >= md->phys_addr && base < end) {
72 ret = (base + size) <= end;
73 break;
74 }
75 }
76
77 efi_bs_call(free_pool, memory_map);
78
79 return ret;
80 }
81
handle_kernel_image(unsigned long * image_addr,unsigned long * image_size,unsigned long * reserve_addr,unsigned long * reserve_size,efi_loaded_image_t * image)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 {
88 efi_status_t status;
89 unsigned long kernel_size, kernel_memsize = 0;
90 u32 phys_seed = 0;
91
92 /*
93 * Although relocatable kernels can fix up the misalignment with
94 * respect to MIN_KIMG_ALIGN, the resulting virtual text addresses are
95 * subtly out of sync with those recorded in the vmlinux when kaslr is
96 * disabled but the image required relocation anyway. Therefore retain
97 * 2M alignment if KASLR was explicitly disabled, even if it was not
98 * going to be activated to begin with.
99 */
100 u64 min_kimg_align = efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
101
102 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
103 if (!efi_nokaslr) {
104 status = efi_get_random_bytes(sizeof(phys_seed),
105 (u8 *)&phys_seed);
106 if (status == EFI_NOT_FOUND) {
107 efi_info("EFI_RNG_PROTOCOL unavailable\n");
108 efi_nokaslr = true;
109 } else if (status != EFI_SUCCESS) {
110 efi_err("efi_get_random_bytes() failed (0x%lx)\n",
111 status);
112 efi_nokaslr = true;
113 }
114 } else {
115 efi_info("KASLR disabled on kernel command line\n");
116 }
117 }
118
119 if (image->image_base != _text)
120 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
121
122 if (!IS_ALIGNED((u64)_text, EFI_KIMG_ALIGN))
123 efi_err("FIRMWARE BUG: kernel image not aligned on %ldk boundary\n",
124 EFI_KIMG_ALIGN >> 10);
125
126 kernel_size = _edata - _text;
127 kernel_memsize = kernel_size + (_end - _edata);
128 *reserve_size = kernel_memsize;
129
130 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
131 /*
132 * If KASLR is enabled, and we have some randomness available,
133 * locate the kernel at a randomized offset in physical memory.
134 */
135 status = efi_random_alloc(*reserve_size, min_kimg_align,
136 reserve_addr, phys_seed);
137 if (status != EFI_SUCCESS)
138 efi_warn("efi_random_alloc() failed: 0x%lx\n", status);
139 } else {
140 status = EFI_OUT_OF_RESOURCES;
141 }
142
143 if (status != EFI_SUCCESS) {
144 if (!check_image_region((u64)_text, kernel_memsize)) {
145 efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n");
146 } else if (IS_ALIGNED((u64)_text, min_kimg_align)) {
147 /*
148 * Just execute from wherever we were loaded by the
149 * UEFI PE/COFF loader if the alignment is suitable.
150 */
151 *image_addr = (u64)_text;
152 *reserve_size = 0;
153 return EFI_SUCCESS;
154 }
155
156 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
157 ULONG_MAX, min_kimg_align);
158
159 if (status != EFI_SUCCESS) {
160 efi_err("Failed to relocate kernel\n");
161 *reserve_size = 0;
162 return status;
163 }
164 }
165
166 *image_addr = *reserve_addr;
167 memcpy((void *)*image_addr, _text, kernel_size);
168
169 return EFI_SUCCESS;
170 }
171