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
15static int __initdata tbl_size;
16unsigned 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 */
22int __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(efi_mem_attr_table, 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(efi_mem_attr_table, tbl_size);
44	set_bit(EFI_MEM_ATTR, &efi.flags);
45
46unmap:
47	early_memunmap(tbl, 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 */
56static 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 */
128int __init efi_memattr_apply_permissions(struct mm_struct *mm,
129					 efi_memattr_perm_setter fn)
130{
131	efi_memory_attributes_table_t *tbl;
132	int i, ret;
133
134	if (tbl_size <= sizeof(*tbl))
135		return 0;
136
137	/*
138	 * We need the EFI memory map to be setup so we can use it to
139	 * lookup the virtual addresses of all entries in the  of EFI
140	 * Memory Attributes table. If it isn't available, this
141	 * function should not be called.
142	 */
143	if (WARN_ON(!efi_enabled(EFI_MEMMAP)))
144		return 0;
145
146	tbl = memremap(efi_mem_attr_table, tbl_size, MEMREMAP_WB);
147	if (!tbl) {
148		pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
149		       efi_mem_attr_table);
150		return -ENOMEM;
151	}
152
153	if (efi_enabled(EFI_DBG))
154		pr_info("Processing EFI Memory Attributes table:\n");
155
156	for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) {
157		efi_memory_desc_t md;
158		unsigned long size;
159		bool valid;
160		char buf[64];
161
162		valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size,
163				       &md);
164		size = md.num_pages << EFI_PAGE_SHIFT;
165		if (efi_enabled(EFI_DBG) || !valid)
166			pr_info("%s 0x%012llx-0x%012llx %s\n",
167				valid ? "" : "!", md.phys_addr,
168				md.phys_addr + size - 1,
169				efi_md_typeattr_format(buf, sizeof(buf), &md));
170
171		if (valid) {
172			ret = fn(mm, &md);
173			if (ret)
174				pr_err("Error updating mappings, skipping subsequent md's\n");
175		}
176	}
177	memunmap(tbl);
178	return ret;
179}
180