1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Extensible Firmware Interface
4  *
5  * Based on Extensible Firmware Interface Specification version 2.4
6  *
7  * Copyright (C) 2013, 2014 Linaro Ltd.
8  */
9 
10 #include <linux/dmi.h>
11 #include <linux/efi.h>
12 #include <linux/io.h>
13 #include <linux/memblock.h>
14 #include <linux/mm_types.h>
15 #include <linux/preempt.h>
16 #include <linux/rbtree.h>
17 #include <linux/rwsem.h>
18 #include <linux/sched.h>
19 #include <linux/slab.h>
20 #include <linux/spinlock.h>
21 
22 #include <asm/cacheflush.h>
23 #include <asm/efi.h>
24 #include <asm/mmu.h>
25 #include <asm/pgalloc.h>
26 #include <asm/pgtable.h>
27 
28 extern u64 efi_system_table;
29 
30 #ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
31 #include <asm/ptdump.h>
32 
33 static struct ptdump_info efi_ptdump_info = {
34 	.mm		= &efi_mm,
35 	.markers	= (struct addr_marker[]){
36 		{ 0,				"UEFI runtime start" },
37 		{ DEFAULT_MAP_WINDOW_64,	"UEFI runtime end" },
38 		{ -1,				NULL }
39 	},
40 	.base_addr	= 0,
41 };
42 
43 static int __init ptdump_init(void)
44 {
45 	if (efi_enabled(EFI_RUNTIME_SERVICES))
46 		ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
47 
48 	return 0;
49 }
50 device_initcall(ptdump_init);
51 
52 #endif
53 
54 static bool __init efi_virtmap_init(void)
55 {
56 	efi_memory_desc_t *md;
57 	bool systab_found;
58 
59 	efi_mm.pgd = pgd_alloc(&efi_mm);
60 	mm_init_cpumask(&efi_mm);
61 	init_new_context(NULL, &efi_mm);
62 
63 	systab_found = false;
64 	for_each_efi_memory_desc(md) {
65 		phys_addr_t phys = md->phys_addr;
66 		int ret;
67 
68 		if (!(md->attribute & EFI_MEMORY_RUNTIME))
69 			continue;
70 		if (md->virt_addr == 0)
71 			return false;
72 
73 		ret = efi_create_mapping(&efi_mm, md);
74 		if (ret) {
75 			pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
76 				&phys, ret);
77 			return false;
78 		}
79 		/*
80 		 * If this entry covers the address of the UEFI system table,
81 		 * calculate and record its virtual address.
82 		 */
83 		if (efi_system_table >= phys &&
84 		    efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
85 			efi.systab = (void *)(unsigned long)(efi_system_table -
86 							     phys + md->virt_addr);
87 			systab_found = true;
88 		}
89 	}
90 	if (!systab_found) {
91 		pr_err("No virtual mapping found for the UEFI System Table\n");
92 		return false;
93 	}
94 
95 	if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
96 		return false;
97 
98 	return true;
99 }
100 
101 /*
102  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
103  * non-early mapping of the UEFI system table and virtual mappings for all
104  * EFI_MEMORY_RUNTIME regions.
105  */
106 static int __init arm_enable_runtime_services(void)
107 {
108 	u64 mapsize;
109 
110 	if (!efi_enabled(EFI_BOOT)) {
111 		pr_info("EFI services will not be available.\n");
112 		return 0;
113 	}
114 
115 	efi_memmap_unmap();
116 
117 	mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
118 
119 	if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
120 		pr_err("Failed to remap EFI memory map\n");
121 		return 0;
122 	}
123 
124 	if (efi_runtime_disabled()) {
125 		pr_info("EFI runtime services will be disabled.\n");
126 		return 0;
127 	}
128 
129 	if (efi_enabled(EFI_RUNTIME_SERVICES)) {
130 		pr_info("EFI runtime services access via paravirt.\n");
131 		return 0;
132 	}
133 
134 	pr_info("Remapping and enabling EFI services.\n");
135 
136 	if (!efi_virtmap_init()) {
137 		pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
138 		return -ENOMEM;
139 	}
140 
141 	/* Set up runtime services function pointers */
142 	efi_native_runtime_setup();
143 	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
144 
145 	return 0;
146 }
147 early_initcall(arm_enable_runtime_services);
148 
149 void efi_virtmap_load(void)
150 {
151 	preempt_disable();
152 	efi_set_pgd(&efi_mm);
153 }
154 
155 void efi_virtmap_unload(void)
156 {
157 	efi_set_pgd(current->active_mm);
158 	preempt_enable();
159 }
160 
161 
162 static int __init arm_dmi_init(void)
163 {
164 	/*
165 	 * On arm64/ARM, DMI depends on UEFI, and dmi_scan_machine() needs to
166 	 * be called early because dmi_id_init(), which is an arch_initcall
167 	 * itself, depends on dmi_scan_machine() having been called already.
168 	 */
169 	dmi_scan_machine();
170 	if (dmi_available)
171 		dmi_set_dump_stack_arch_desc();
172 	return 0;
173 }
174 core_initcall(arm_dmi_init);
175