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
system_needs_vamap(void)18 static bool system_needs_vamap(void)
19 {
20 const u8 *type1_family = efi_get_smbios_string(1, family);
21
22 /*
23 * Ampere Altra machines crash in SetTime() if SetVirtualAddressMap()
24 * has not been called prior.
25 */
26 if (!type1_family || strcmp(type1_family, "Altra"))
27 return false;
28
29 efi_warn("Working around broken SetVirtualAddressMap()\n");
30 return true;
31 }
32
check_platform_features(void)33 efi_status_t check_platform_features(void)
34 {
35 u64 tg;
36
37 /*
38 * If we have 48 bits of VA space for TTBR0 mappings, we can map the
39 * UEFI runtime regions 1:1 and so calling SetVirtualAddressMap() is
40 * unnecessary.
41 */
42 if (VA_BITS_MIN >= 48 && !system_needs_vamap())
43 efi_novamap = true;
44
45 /* UEFI mandates support for 4 KB granularity, no need to check */
46 if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
47 return EFI_SUCCESS;
48
49 tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_EL1_TGRAN_SHIFT) & 0xf;
50 if (tg < ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MIN || tg > ID_AA64MMFR0_EL1_TGRAN_SUPPORTED_MAX) {
51 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
52 efi_err("This 64 KB granular kernel is not supported by your CPU\n");
53 else
54 efi_err("This 16 KB granular kernel is not supported by your CPU\n");
55 return EFI_UNSUPPORTED;
56 }
57 return EFI_SUCCESS;
58 }
59
60 /*
61 * Distro versions of GRUB may ignore the BSS allocation entirely (i.e., fail
62 * to provide space, and fail to zero it). Check for this condition by double
63 * checking that the first and the last byte of the image are covered by the
64 * same EFI memory map entry.
65 */
check_image_region(u64 base,u64 size)66 static bool check_image_region(u64 base, u64 size)
67 {
68 struct efi_boot_memmap *map;
69 efi_status_t status;
70 bool ret = false;
71 int map_offset;
72
73 status = efi_get_memory_map(&map, false);
74 if (status != EFI_SUCCESS)
75 return false;
76
77 for (map_offset = 0; map_offset < map->map_size; map_offset += map->desc_size) {
78 efi_memory_desc_t *md = (void *)map->map + map_offset;
79 u64 end = md->phys_addr + md->num_pages * EFI_PAGE_SIZE;
80
81 /*
82 * Find the region that covers base, and return whether
83 * it covers base+size bytes.
84 */
85 if (base >= md->phys_addr && base < end) {
86 ret = (base + size) <= end;
87 break;
88 }
89 }
90
91 efi_bs_call(free_pool, map);
92
93 return ret;
94 }
95
handle_kernel_image(unsigned long * image_addr,unsigned long * image_size,unsigned long * reserve_addr,unsigned long * reserve_size,efi_loaded_image_t * image,efi_handle_t image_handle)96 efi_status_t handle_kernel_image(unsigned long *image_addr,
97 unsigned long *image_size,
98 unsigned long *reserve_addr,
99 unsigned long *reserve_size,
100 efi_loaded_image_t *image,
101 efi_handle_t image_handle)
102 {
103 efi_status_t status;
104 unsigned long kernel_size, kernel_memsize = 0;
105 u32 phys_seed = 0;
106
107 /*
108 * Although relocatable kernels can fix up the misalignment with
109 * respect to MIN_KIMG_ALIGN, the resulting virtual text addresses are
110 * subtly out of sync with those recorded in the vmlinux when kaslr is
111 * disabled but the image required relocation anyway. Therefore retain
112 * 2M alignment if KASLR was explicitly disabled, even if it was not
113 * going to be activated to begin with.
114 */
115 u64 min_kimg_align = efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
116
117 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
118 efi_guid_t li_fixed_proto = LINUX_EFI_LOADED_IMAGE_FIXED_GUID;
119 void *p;
120
121 if (efi_nokaslr) {
122 efi_info("KASLR disabled on kernel command line\n");
123 } else if (efi_bs_call(handle_protocol, image_handle,
124 &li_fixed_proto, &p) == EFI_SUCCESS) {
125 efi_info("Image placement fixed by loader\n");
126 } else {
127 status = efi_get_random_bytes(sizeof(phys_seed),
128 (u8 *)&phys_seed);
129 if (status == EFI_NOT_FOUND) {
130 efi_info("EFI_RNG_PROTOCOL unavailable\n");
131 efi_nokaslr = true;
132 } else if (status != EFI_SUCCESS) {
133 efi_err("efi_get_random_bytes() failed (0x%lx)\n",
134 status);
135 efi_nokaslr = true;
136 }
137 }
138 }
139
140 if (image->image_base != _text)
141 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
142
143 if (!IS_ALIGNED((u64)_text, SEGMENT_ALIGN))
144 efi_err("FIRMWARE BUG: kernel image not aligned on %dk boundary\n",
145 SEGMENT_ALIGN >> 10);
146
147 kernel_size = _edata - _text;
148 kernel_memsize = kernel_size + (_end - _edata);
149 *reserve_size = kernel_memsize;
150
151 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
152 /*
153 * If KASLR is enabled, and we have some randomness available,
154 * locate the kernel at a randomized offset in physical memory.
155 */
156 status = efi_random_alloc(*reserve_size, min_kimg_align,
157 reserve_addr, phys_seed);
158 if (status != EFI_SUCCESS)
159 efi_warn("efi_random_alloc() failed: 0x%lx\n", status);
160 } else {
161 status = EFI_OUT_OF_RESOURCES;
162 }
163
164 if (status != EFI_SUCCESS) {
165 if (!check_image_region((u64)_text, kernel_memsize)) {
166 efi_err("FIRMWARE BUG: Image BSS overlaps adjacent EFI memory region\n");
167 } else if (IS_ALIGNED((u64)_text, min_kimg_align)) {
168 /*
169 * Just execute from wherever we were loaded by the
170 * UEFI PE/COFF loader if the alignment is suitable.
171 */
172 *image_addr = (u64)_text;
173 *reserve_size = 0;
174 return EFI_SUCCESS;
175 }
176
177 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
178 ULONG_MAX, min_kimg_align);
179
180 if (status != EFI_SUCCESS) {
181 efi_err("Failed to relocate kernel\n");
182 *reserve_size = 0;
183 return status;
184 }
185 }
186
187 *image_addr = *reserve_addr;
188 memcpy((void *)*image_addr, _text, kernel_size);
189
190 return EFI_SUCCESS;
191 }
192