1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Common EFI memory map functions.
4 */
5
6#define pr_fmt(fmt) "efi: " fmt
7
8#include <linux/init.h>
9#include <linux/kernel.h>
10#include <linux/efi.h>
11#include <linux/io.h>
12#include <linux/memblock.h>
13#include <linux/slab.h>
14
15#include <asm/early_ioremap.h>
16#include <asm/efi.h>
17
18/**
19 * __efi_memmap_init - Common code for mapping the EFI memory map
20 * @data: EFI memory map data
21 *
22 * This function takes care of figuring out which function to use to
23 * map the EFI memory map in efi.memmap based on how far into the boot
24 * we are.
25 *
26 * During bootup EFI_MEMMAP_LATE in data->flags should be clear since we
27 * only have access to the early_memremap*() functions as the vmalloc
28 * space isn't setup. Once the kernel is fully booted we can fallback
29 * to the more robust memremap*() API.
30 *
31 * Returns: zero on success, a negative error code on failure.
32 */
33int __init __efi_memmap_init(struct efi_memory_map_data *data)
34{
35 struct efi_memory_map map;
36 phys_addr_t phys_map;
37
38 phys_map = data->phys_map;
39
40 if (data->flags & EFI_MEMMAP_LATE)
41 map.map = memremap(offset: phys_map, size: data->size, flags: MEMREMAP_WB);
42 else
43 map.map = early_memremap(phys_addr: phys_map, size: data->size);
44
45 if (!map.map) {
46 pr_err("Could not map the memory map! phys_map=%pa, size=0x%lx\n",
47 &phys_map, data->size);
48 return -ENOMEM;
49 }
50
51 map.phys_map = data->phys_map;
52 map.nr_map = data->size / data->desc_size;
53 map.map_end = map.map + data->size;
54
55 map.desc_version = data->desc_version;
56 map.desc_size = data->desc_size;
57 map.flags = data->flags;
58
59 set_bit(EFI_MEMMAP, addr: &efi.flags);
60
61 efi.memmap = map;
62
63 return 0;
64}
65
66/**
67 * efi_memmap_init_early - Map the EFI memory map data structure
68 * @data: EFI memory map data
69 *
70 * Use early_memremap() to map the passed in EFI memory map and assign
71 * it to efi.memmap.
72 *
73 * Returns: zero on success, a negative error code on failure.
74 */
75int __init efi_memmap_init_early(struct efi_memory_map_data *data)
76{
77 /* Cannot go backwards */
78 WARN_ON(efi.memmap.flags & EFI_MEMMAP_LATE);
79
80 data->flags = 0;
81 return __efi_memmap_init(data);
82}
83
84void __init efi_memmap_unmap(void)
85{
86 if (!efi_enabled(EFI_MEMMAP))
87 return;
88
89 if (!(efi.memmap.flags & EFI_MEMMAP_LATE)) {
90 unsigned long size;
91
92 size = efi.memmap.desc_size * efi.memmap.nr_map;
93 early_memunmap(addr: efi.memmap.map, size);
94 } else {
95 memunmap(addr: efi.memmap.map);
96 }
97
98 efi.memmap.map = NULL;
99 clear_bit(EFI_MEMMAP, addr: &efi.flags);
100}
101
102/**
103 * efi_memmap_init_late - Map efi.memmap with memremap()
104 * @addr: Physical address of the new EFI memory map
105 * @size: Size in bytes of the new EFI memory map
106 *
107 * Setup a mapping of the EFI memory map using ioremap_cache(). This
108 * function should only be called once the vmalloc space has been
109 * setup and is therefore not suitable for calling during early EFI
110 * initialise, e.g. in efi_init(). Additionally, it expects
111 * efi_memmap_init_early() to have already been called.
112 *
113 * The reason there are two EFI memmap initialisation
114 * (efi_memmap_init_early() and this late version) is because the
115 * early EFI memmap should be explicitly unmapped once EFI
116 * initialisation is complete as the fixmap space used to map the EFI
117 * memmap (via early_memremap()) is a scarce resource.
118 *
119 * This late mapping is intended to persist for the duration of
120 * runtime so that things like efi_mem_desc_lookup() and
121 * efi_mem_attributes() always work.
122 *
123 * Returns: zero on success, a negative error code on failure.
124 */
125int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
126{
127 struct efi_memory_map_data data = {
128 .phys_map = addr,
129 .size = size,
130 .flags = EFI_MEMMAP_LATE,
131 };
132
133 /* Did we forget to unmap the early EFI memmap? */
134 WARN_ON(efi.memmap.map);
135
136 /* Were we already called? */
137 WARN_ON(efi.memmap.flags & EFI_MEMMAP_LATE);
138
139 /*
140 * It makes no sense to allow callers to register different
141 * values for the following fields. Copy them out of the
142 * existing early EFI memmap.
143 */
144 data.desc_version = efi.memmap.desc_version;
145 data.desc_size = efi.memmap.desc_size;
146
147 return __efi_memmap_init(data: &data);
148}
149