1 /*
2  * Extensible Firmware Interface
3  *
4  * Based on Extensible Firmware Interface Specification version 2.4
5  *
6  * Copyright (C) 2013, 2014 Linaro Ltd.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  *
12  */
13 
14 #include <linux/dmi.h>
15 #include <linux/efi.h>
16 #include <linux/io.h>
17 #include <linux/memblock.h>
18 #include <linux/mm_types.h>
19 #include <linux/preempt.h>
20 #include <linux/rbtree.h>
21 #include <linux/rwsem.h>
22 #include <linux/sched.h>
23 #include <linux/slab.h>
24 #include <linux/spinlock.h>
25 
26 #include <asm/cacheflush.h>
27 #include <asm/efi.h>
28 #include <asm/mmu.h>
29 #include <asm/pgalloc.h>
30 #include <asm/pgtable.h>
31 
32 extern u64 efi_system_table;
33 
34 #ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
35 #include <asm/ptdump.h>
36 
37 static struct ptdump_info efi_ptdump_info = {
38 	.mm		= &efi_mm,
39 	.markers	= (struct addr_marker[]){
40 		{ 0,				"UEFI runtime start" },
41 		{ DEFAULT_MAP_WINDOW_64,	"UEFI runtime end" },
42 		{ -1,				NULL }
43 	},
44 	.base_addr	= 0,
45 };
46 
47 static int __init ptdump_init(void)
48 {
49 	if (!efi_enabled(EFI_RUNTIME_SERVICES))
50 		return 0;
51 
52 	return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
53 }
54 device_initcall(ptdump_init);
55 
56 #endif
57 
58 static bool __init efi_virtmap_init(void)
59 {
60 	efi_memory_desc_t *md;
61 	bool systab_found;
62 
63 	efi_mm.pgd = pgd_alloc(&efi_mm);
64 	mm_init_cpumask(&efi_mm);
65 	init_new_context(NULL, &efi_mm);
66 
67 	systab_found = false;
68 	for_each_efi_memory_desc(md) {
69 		phys_addr_t phys = md->phys_addr;
70 		int ret;
71 
72 		if (!(md->attribute & EFI_MEMORY_RUNTIME))
73 			continue;
74 		if (md->virt_addr == 0)
75 			return false;
76 
77 		ret = efi_create_mapping(&efi_mm, md);
78 		if (ret) {
79 			pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
80 				&phys, ret);
81 			return false;
82 		}
83 		/*
84 		 * If this entry covers the address of the UEFI system table,
85 		 * calculate and record its virtual address.
86 		 */
87 		if (efi_system_table >= phys &&
88 		    efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
89 			efi.systab = (void *)(unsigned long)(efi_system_table -
90 							     phys + md->virt_addr);
91 			systab_found = true;
92 		}
93 	}
94 	if (!systab_found) {
95 		pr_err("No virtual mapping found for the UEFI System Table\n");
96 		return false;
97 	}
98 
99 	if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
100 		return false;
101 
102 	return true;
103 }
104 
105 /*
106  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
107  * non-early mapping of the UEFI system table and virtual mappings for all
108  * EFI_MEMORY_RUNTIME regions.
109  */
110 static int __init arm_enable_runtime_services(void)
111 {
112 	u64 mapsize;
113 
114 	if (!efi_enabled(EFI_BOOT)) {
115 		pr_info("EFI services will not be available.\n");
116 		return 0;
117 	}
118 
119 	efi_memmap_unmap();
120 
121 	mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
122 
123 	if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
124 		pr_err("Failed to remap EFI memory map\n");
125 		return 0;
126 	}
127 
128 	if (efi_runtime_disabled()) {
129 		pr_info("EFI runtime services will be disabled.\n");
130 		return 0;
131 	}
132 
133 	if (efi_enabled(EFI_RUNTIME_SERVICES)) {
134 		pr_info("EFI runtime services access via paravirt.\n");
135 		return 0;
136 	}
137 
138 	pr_info("Remapping and enabling EFI services.\n");
139 
140 	if (!efi_virtmap_init()) {
141 		pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
142 		return -ENOMEM;
143 	}
144 
145 	/* Set up runtime services function pointers */
146 	efi_native_runtime_setup();
147 	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
148 
149 	return 0;
150 }
151 early_initcall(arm_enable_runtime_services);
152 
153 void efi_virtmap_load(void)
154 {
155 	preempt_disable();
156 	efi_set_pgd(&efi_mm);
157 }
158 
159 void efi_virtmap_unload(void)
160 {
161 	efi_set_pgd(current->active_mm);
162 	preempt_enable();
163 }
164 
165 
166 static int __init arm_dmi_init(void)
167 {
168 	/*
169 	 * On arm64/ARM, DMI depends on UEFI, and dmi_scan_machine() needs to
170 	 * be called early because dmi_id_init(), which is an arch_initcall
171 	 * itself, depends on dmi_scan_machine() having been called already.
172 	 */
173 	dmi_scan_machine();
174 	if (dmi_available)
175 		dmi_set_dump_stack_arch_desc();
176 	return 0;
177 }
178 core_initcall(arm_dmi_init);
179