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 * To prevent the compiler from emitting GOT-indirected (and thus absolute)
11 * references to the section markers, override their visibility as 'hidden'
12 */
13 #pragma GCC visibility push(hidden)
14 #include <asm/sections.h>
15 #pragma GCC visibility pop
16
17 #include <linux/efi.h>
18 #include <asm/efi.h>
19 #include <asm/memory.h>
20 #include <asm/sysreg.h>
21
22 #include "efistub.h"
23
24 efi_status_t check_platform_features(efi_system_table_t *sys_table_arg)
25 {
26 u64 tg;
27
28 /* UEFI mandates support for 4 KB granularity, no need to check */
29 if (IS_ENABLED(CONFIG_ARM64_4K_PAGES))
30 return EFI_SUCCESS;
31
32 tg = (read_cpuid(ID_AA64MMFR0_EL1) >> ID_AA64MMFR0_TGRAN_SHIFT) & 0xf;
33 if (tg != ID_AA64MMFR0_TGRAN_SUPPORTED) {
34 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
35 pr_efi_err(sys_table_arg, "This 64 KB granular kernel is not supported by your CPU\n");
36 else
37 pr_efi_err(sys_table_arg, "This 16 KB granular kernel is not supported by your CPU\n");
38 return EFI_UNSUPPORTED;
39 }
40 return EFI_SUCCESS;
41 }
42
43 efi_status_t handle_kernel_image(efi_system_table_t *sys_table_arg,
44 unsigned long *image_addr,
45 unsigned long *image_size,
46 unsigned long *reserve_addr,
47 unsigned long *reserve_size,
48 unsigned long dram_base,
49 efi_loaded_image_t *image)
50 {
51 efi_status_t status;
52 unsigned long kernel_size, kernel_memsize = 0;
53 void *old_image_addr = (void *)*image_addr;
54 unsigned long preferred_offset;
55 u64 phys_seed = 0;
56
57 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
58 if (!nokaslr()) {
59 status = efi_get_random_bytes(sys_table_arg,
60 sizeof(phys_seed),
61 (u8 *)&phys_seed);
62 if (status == EFI_NOT_FOUND) {
63 pr_efi(sys_table_arg, "EFI_RNG_PROTOCOL unavailable, no randomness supplied\n");
64 } else if (status != EFI_SUCCESS) {
65 pr_efi_err(sys_table_arg, "efi_get_random_bytes() failed\n");
66 return status;
67 }
68 } else {
69 pr_efi(sys_table_arg, "KASLR disabled on kernel command line\n");
70 }
71 }
72
73 /*
74 * The preferred offset of the kernel Image is TEXT_OFFSET bytes beyond
75 * a 2 MB aligned base, which itself may be lower than dram_base, as
76 * long as the resulting offset equals or exceeds it.
77 */
78 preferred_offset = round_down(dram_base, MIN_KIMG_ALIGN) + TEXT_OFFSET;
79 if (preferred_offset < dram_base)
80 preferred_offset += MIN_KIMG_ALIGN;
81
82 kernel_size = _edata - _text;
83 kernel_memsize = kernel_size + (_end - _edata);
84
85 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
86 /*
87 * If CONFIG_DEBUG_ALIGN_RODATA is not set, produce a
88 * displacement in the interval [0, MIN_KIMG_ALIGN) that
89 * doesn't violate this kernel's de-facto alignment
90 * constraints.
91 */
92 u32 mask = (MIN_KIMG_ALIGN - 1) & ~(EFI_KIMG_ALIGN - 1);
93 u32 offset = !IS_ENABLED(CONFIG_DEBUG_ALIGN_RODATA) ?
94 (phys_seed >> 32) & mask : TEXT_OFFSET;
95
96 /*
97 * With CONFIG_RANDOMIZE_TEXT_OFFSET=y, TEXT_OFFSET may not
98 * be a multiple of EFI_KIMG_ALIGN, and we must ensure that
99 * we preserve the misalignment of 'offset' relative to
100 * EFI_KIMG_ALIGN so that statically allocated objects whose
101 * alignment exceeds PAGE_SIZE appear correctly aligned in
102 * memory.
103 */
104 offset |= TEXT_OFFSET % EFI_KIMG_ALIGN;
105
106 /*
107 * If KASLR is enabled, and we have some randomness available,
108 * locate the kernel at a randomized offset in physical memory.
109 */
110 *reserve_size = kernel_memsize + offset;
111 status = efi_random_alloc(sys_table_arg, *reserve_size,
112 MIN_KIMG_ALIGN, reserve_addr,
113 (u32)phys_seed);
114
115 *image_addr = *reserve_addr + offset;
116 } else {
117 /*
118 * Else, try a straight allocation at the preferred offset.
119 * This will work around the issue where, if dram_base == 0x0,
120 * efi_low_alloc() refuses to allocate at 0x0 (to prevent the
121 * address of the allocation to be mistaken for a FAIL return
122 * value or a NULL pointer). It will also ensure that, on
123 * platforms where the [dram_base, dram_base + TEXT_OFFSET)
124 * interval is partially occupied by the firmware (like on APM
125 * Mustang), we can still place the kernel at the address
126 * 'dram_base + TEXT_OFFSET'.
127 */
128 if (*image_addr == preferred_offset)
129 return EFI_SUCCESS;
130
131 *image_addr = *reserve_addr = preferred_offset;
132 *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN);
133
134 status = efi_call_early(allocate_pages, EFI_ALLOCATE_ADDRESS,
135 EFI_LOADER_DATA,
136 *reserve_size / EFI_PAGE_SIZE,
137 (efi_physical_addr_t *)reserve_addr);
138 }
139
140 if (status != EFI_SUCCESS) {
141 *reserve_size = kernel_memsize + TEXT_OFFSET;
142 status = efi_low_alloc(sys_table_arg, *reserve_size,
143 MIN_KIMG_ALIGN, reserve_addr);
144
145 if (status != EFI_SUCCESS) {
146 pr_efi_err(sys_table_arg, "Failed to relocate kernel\n");
147 *reserve_size = 0;
148 return status;
149 }
150 *image_addr = *reserve_addr + TEXT_OFFSET;
151 }
152 memcpy((void *)*image_addr, old_image_addr, kernel_size);
153
154 return EFI_SUCCESS;
155 }