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/efi.h>
15 #include <linux/io.h>
16 #include <linux/memblock.h>
17 #include <linux/mm_types.h>
18 #include <linux/preempt.h>
19 #include <linux/rbtree.h>
20 #include <linux/rwsem.h>
21 #include <linux/sched.h>
22 #include <linux/slab.h>
23 #include <linux/spinlock.h>
24 
25 #include <asm/cacheflush.h>
26 #include <asm/efi.h>
27 #include <asm/mmu.h>
28 #include <asm/pgalloc.h>
29 #include <asm/pgtable.h>
30 
31 extern u64 efi_system_table;
32 
33 static struct mm_struct efi_mm = {
34 	.mm_rb			= RB_ROOT,
35 	.mm_users		= ATOMIC_INIT(2),
36 	.mm_count		= ATOMIC_INIT(1),
37 	.mmap_sem		= __RWSEM_INITIALIZER(efi_mm.mmap_sem),
38 	.page_table_lock	= __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
39 	.mmlist			= LIST_HEAD_INIT(efi_mm.mmlist),
40 };
41 
42 #ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
43 #include <asm/ptdump.h>
44 
45 static struct ptdump_info efi_ptdump_info = {
46 	.mm		= &efi_mm,
47 	.markers	= (struct addr_marker[]){
48 		{ 0,		"UEFI runtime start" },
49 		{ TASK_SIZE_64,	"UEFI runtime end" }
50 	},
51 	.base_addr	= 0,
52 };
53 
54 static int __init ptdump_init(void)
55 {
56 	return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
57 }
58 device_initcall(ptdump_init);
59 
60 #endif
61 
62 static bool __init efi_virtmap_init(void)
63 {
64 	efi_memory_desc_t *md;
65 	bool systab_found;
66 
67 	efi_mm.pgd = pgd_alloc(&efi_mm);
68 	init_new_context(NULL, &efi_mm);
69 
70 	systab_found = false;
71 	for_each_efi_memory_desc(md) {
72 		phys_addr_t phys = md->phys_addr;
73 		int ret;
74 
75 		if (!(md->attribute & EFI_MEMORY_RUNTIME))
76 			continue;
77 		if (md->virt_addr == 0)
78 			return false;
79 
80 		ret = efi_create_mapping(&efi_mm, md);
81 		if  (!ret) {
82 			pr_info("  EFI remap %pa => %p\n",
83 				&phys, (void *)(unsigned long)md->virt_addr);
84 		} else {
85 			pr_warn("  EFI remap %pa: failed to create mapping (%d)\n",
86 				&phys, ret);
87 			return false;
88 		}
89 		/*
90 		 * If this entry covers the address of the UEFI system table,
91 		 * calculate and record its virtual address.
92 		 */
93 		if (efi_system_table >= phys &&
94 		    efi_system_table < phys + (md->num_pages * EFI_PAGE_SIZE)) {
95 			efi.systab = (void *)(unsigned long)(efi_system_table -
96 							     phys + md->virt_addr);
97 			systab_found = true;
98 		}
99 	}
100 	if (!systab_found) {
101 		pr_err("No virtual mapping found for the UEFI System Table\n");
102 		return false;
103 	}
104 
105 	if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
106 		return false;
107 
108 	return true;
109 }
110 
111 /*
112  * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
113  * non-early mapping of the UEFI system table and virtual mappings for all
114  * EFI_MEMORY_RUNTIME regions.
115  */
116 static int __init arm_enable_runtime_services(void)
117 {
118 	u64 mapsize;
119 
120 	if (!efi_enabled(EFI_BOOT)) {
121 		pr_info("EFI services will not be available.\n");
122 		return 0;
123 	}
124 
125 	if (efi_runtime_disabled()) {
126 		pr_info("EFI runtime services will be disabled.\n");
127 		return 0;
128 	}
129 
130 	if (efi_enabled(EFI_RUNTIME_SERVICES)) {
131 		pr_info("EFI runtime services access via paravirt.\n");
132 		return 0;
133 	}
134 
135 	pr_info("Remapping and enabling EFI services.\n");
136 
137 	mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
138 
139 	if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
140 		pr_err("Failed to remap EFI memory map\n");
141 		return -ENOMEM;
142 	}
143 
144 	if (!efi_virtmap_init()) {
145 		pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
146 		return -ENOMEM;
147 	}
148 
149 	/* Set up runtime services function pointers */
150 	efi_native_runtime_setup();
151 	set_bit(EFI_RUNTIME_SERVICES, &efi.flags);
152 
153 	return 0;
154 }
155 early_initcall(arm_enable_runtime_services);
156 
157 void efi_virtmap_load(void)
158 {
159 	preempt_disable();
160 	efi_set_pgd(&efi_mm);
161 }
162 
163 void efi_virtmap_unload(void)
164 {
165 	efi_set_pgd(current->active_mm);
166 	preempt_enable();
167 }
168