1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright (C) 2016 Linaro Ltd. <ard.biesheuvel@linaro.org> |
4 | */ |
5 | |
6 | #define pr_fmt(fmt) "efi: memattr: " fmt |
7 | |
8 | #include <linux/efi.h> |
9 | #include <linux/init.h> |
10 | #include <linux/io.h> |
11 | #include <linux/memblock.h> |
12 | |
13 | #include <asm/early_ioremap.h> |
14 | |
15 | static int __initdata tbl_size; |
16 | unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR; |
17 | |
18 | /* |
19 | * Reserve the memory associated with the Memory Attributes configuration |
20 | * table, if it exists. |
21 | */ |
22 | int __init efi_memattr_init(void) |
23 | { |
24 | efi_memory_attributes_table_t *tbl; |
25 | |
26 | if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR) |
27 | return 0; |
28 | |
29 | tbl = early_memremap(phys_addr: efi_mem_attr_table, size: sizeof(*tbl)); |
30 | if (!tbl) { |
31 | pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n" , |
32 | efi_mem_attr_table); |
33 | return -ENOMEM; |
34 | } |
35 | |
36 | if (tbl->version > 2) { |
37 | pr_warn("Unexpected EFI Memory Attributes table version %d\n" , |
38 | tbl->version); |
39 | goto unmap; |
40 | } |
41 | |
42 | tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size; |
43 | memblock_reserve(base: efi_mem_attr_table, size: tbl_size); |
44 | set_bit(EFI_MEM_ATTR, addr: &efi.flags); |
45 | |
46 | unmap: |
47 | early_memunmap(addr: tbl, size: sizeof(*tbl)); |
48 | return 0; |
49 | } |
50 | |
51 | /* |
52 | * Returns a copy @out of the UEFI memory descriptor @in if it is covered |
53 | * entirely by a UEFI memory map entry with matching attributes. The virtual |
54 | * address of @out is set according to the matching entry that was found. |
55 | */ |
56 | static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out) |
57 | { |
58 | u64 in_paddr = in->phys_addr; |
59 | u64 in_size = in->num_pages << EFI_PAGE_SHIFT; |
60 | efi_memory_desc_t *md; |
61 | |
62 | *out = *in; |
63 | |
64 | if (in->type != EFI_RUNTIME_SERVICES_CODE && |
65 | in->type != EFI_RUNTIME_SERVICES_DATA) { |
66 | pr_warn("Entry type should be RuntimeServiceCode/Data\n" ); |
67 | return false; |
68 | } |
69 | |
70 | if (PAGE_SIZE > EFI_PAGE_SIZE && |
71 | (!PAGE_ALIGNED(in->phys_addr) || |
72 | !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) { |
73 | /* |
74 | * Since arm64 may execute with page sizes of up to 64 KB, the |
75 | * UEFI spec mandates that RuntimeServices memory regions must |
76 | * be 64 KB aligned. We need to validate this here since we will |
77 | * not be able to tighten permissions on such regions without |
78 | * affecting adjacent regions. |
79 | */ |
80 | pr_warn("Entry address region misaligned\n" ); |
81 | return false; |
82 | } |
83 | |
84 | for_each_efi_memory_desc(md) { |
85 | u64 md_paddr = md->phys_addr; |
86 | u64 md_size = md->num_pages << EFI_PAGE_SHIFT; |
87 | |
88 | if (!(md->attribute & EFI_MEMORY_RUNTIME)) |
89 | continue; |
90 | if (md->virt_addr == 0 && md->phys_addr != 0) { |
91 | /* no virtual mapping has been installed by the stub */ |
92 | break; |
93 | } |
94 | |
95 | if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size) |
96 | continue; |
97 | |
98 | /* |
99 | * This entry covers the start of @in, check whether |
100 | * it covers the end as well. |
101 | */ |
102 | if (md_paddr + md_size < in_paddr + in_size) { |
103 | pr_warn("Entry covers multiple EFI memory map regions\n" ); |
104 | return false; |
105 | } |
106 | |
107 | if (md->type != in->type) { |
108 | pr_warn("Entry type deviates from EFI memory map region type\n" ); |
109 | return false; |
110 | } |
111 | |
112 | out->virt_addr = in_paddr + (md->virt_addr - md_paddr); |
113 | |
114 | return true; |
115 | } |
116 | |
117 | pr_warn("No matching entry found in the EFI memory map\n" ); |
118 | return false; |
119 | } |
120 | |
121 | /* |
122 | * To be called after the EFI page tables have been populated. If a memory |
123 | * attributes table is available, its contents will be used to update the |
124 | * mappings with tightened permissions as described by the table. |
125 | * This requires the UEFI memory map to have already been populated with |
126 | * virtual addresses. |
127 | */ |
128 | int __init efi_memattr_apply_permissions(struct mm_struct *mm, |
129 | efi_memattr_perm_setter fn) |
130 | { |
131 | efi_memory_attributes_table_t *tbl; |
132 | bool has_bti = false; |
133 | int i, ret; |
134 | |
135 | if (tbl_size <= sizeof(*tbl)) |
136 | return 0; |
137 | |
138 | /* |
139 | * We need the EFI memory map to be setup so we can use it to |
140 | * lookup the virtual addresses of all entries in the of EFI |
141 | * Memory Attributes table. If it isn't available, this |
142 | * function should not be called. |
143 | */ |
144 | if (WARN_ON(!efi_enabled(EFI_MEMMAP))) |
145 | return 0; |
146 | |
147 | tbl = memremap(offset: efi_mem_attr_table, size: tbl_size, flags: MEMREMAP_WB); |
148 | if (!tbl) { |
149 | pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n" , |
150 | efi_mem_attr_table); |
151 | return -ENOMEM; |
152 | } |
153 | |
154 | if (tbl->version > 1 && |
155 | (tbl->flags & EFI_MEMORY_ATTRIBUTES_FLAGS_RT_FORWARD_CONTROL_FLOW_GUARD)) |
156 | has_bti = true; |
157 | |
158 | if (efi_enabled(EFI_DBG)) |
159 | pr_info("Processing EFI Memory Attributes table:\n" ); |
160 | |
161 | for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) { |
162 | efi_memory_desc_t md; |
163 | unsigned long size; |
164 | bool valid; |
165 | char buf[64]; |
166 | |
167 | valid = entry_is_valid(in: (void *)tbl->entry + i * tbl->desc_size, |
168 | out: &md); |
169 | size = md.num_pages << EFI_PAGE_SHIFT; |
170 | if (efi_enabled(EFI_DBG) || !valid) |
171 | pr_info("%s 0x%012llx-0x%012llx %s\n" , |
172 | valid ? "" : "!" , md.phys_addr, |
173 | md.phys_addr + size - 1, |
174 | efi_md_typeattr_format(buf, sizeof(buf), &md)); |
175 | |
176 | if (valid) { |
177 | ret = fn(mm, &md, has_bti); |
178 | if (ret) |
179 | pr_err("Error updating mappings, skipping subsequent md's\n" ); |
180 | } |
181 | } |
182 | memunmap(addr: tbl); |
183 | return ret; |
184 | } |
185 | |