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) {
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 * Although relocatable kernels can fix up the misalignment with respect to
39 * MIN_KIMG_ALIGN, the resulting virtual text addresses are subtly out of
40 * sync with those recorded in the vmlinux when kaslr is disabled but the
41 * image required relocation anyway. Therefore retain 2M alignment unless
42 * KASLR is in use.
43 */
min_kimg_align(void)44 static u64 min_kimg_align(void)
45 {
46 return efi_nokaslr ? MIN_KIMG_ALIGN : EFI_KIMG_ALIGN;
47 }
48
handle_kernel_image(unsigned long * image_addr,unsigned long * image_size,unsigned long * reserve_addr,unsigned long * reserve_size,efi_loaded_image_t * image)49 efi_status_t handle_kernel_image(unsigned long *image_addr,
50 unsigned long *image_size,
51 unsigned long *reserve_addr,
52 unsigned long *reserve_size,
53 efi_loaded_image_t *image)
54 {
55 efi_status_t status;
56 unsigned long kernel_size, kernel_memsize = 0;
57 u32 phys_seed = 0;
58
59 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
60 if (!efi_nokaslr) {
61 status = efi_get_random_bytes(sizeof(phys_seed),
62 (u8 *)&phys_seed);
63 if (status == EFI_NOT_FOUND) {
64 efi_info("EFI_RNG_PROTOCOL unavailable, KASLR will be disabled\n");
65 efi_nokaslr = true;
66 } else if (status != EFI_SUCCESS) {
67 efi_err("efi_get_random_bytes() failed (0x%lx), KASLR will be disabled\n",
68 status);
69 efi_nokaslr = true;
70 }
71 } else {
72 efi_info("KASLR disabled on kernel command line\n");
73 }
74 }
75
76 if (image->image_base != _text)
77 efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n");
78
79 kernel_size = _edata - _text;
80 kernel_memsize = kernel_size + (_end - _edata);
81 *reserve_size = kernel_memsize;
82
83 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && phys_seed != 0) {
84 /*
85 * If KASLR is enabled, and we have some randomness available,
86 * locate the kernel at a randomized offset in physical memory.
87 */
88 status = efi_random_alloc(*reserve_size, min_kimg_align(),
89 reserve_addr, phys_seed);
90 } else {
91 status = EFI_OUT_OF_RESOURCES;
92 }
93
94 if (status != EFI_SUCCESS) {
95 if (IS_ALIGNED((u64)_text, min_kimg_align())) {
96 /*
97 * Just execute from wherever we were loaded by the
98 * UEFI PE/COFF loader if the alignment is suitable.
99 */
100 *image_addr = (u64)_text;
101 *reserve_size = 0;
102 return EFI_SUCCESS;
103 }
104
105 status = efi_allocate_pages_aligned(*reserve_size, reserve_addr,
106 ULONG_MAX, min_kimg_align());
107
108 if (status != EFI_SUCCESS) {
109 efi_err("Failed to relocate kernel\n");
110 *reserve_size = 0;
111 return status;
112 }
113 }
114
115 *image_addr = *reserve_addr;
116 memcpy((void *)*image_addr, _text, kernel_size);
117
118 return EFI_SUCCESS;
119 }
120