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 > 1) {
 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 (!(in->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))) {
 71		pr_warn("Entry attributes invalid: RO and XP bits both cleared\n");
 72		return false;
 73	}
 74
 75	if (PAGE_SIZE > EFI_PAGE_SIZE &&
 76	    (!PAGE_ALIGNED(in->phys_addr) ||
 77	     !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) {
 78		/*
 79		 * Since arm64 may execute with page sizes of up to 64 KB, the
 80		 * UEFI spec mandates that RuntimeServices memory regions must
 81		 * be 64 KB aligned. We need to validate this here since we will
 82		 * not be able to tighten permissions on such regions without
 83		 * affecting adjacent regions.
 84		 */
 85		pr_warn("Entry address region misaligned\n");
 86		return false;
 87	}
 88
 89	for_each_efi_memory_desc(md) {
 90		u64 md_paddr = md->phys_addr;
 91		u64 md_size = md->num_pages << EFI_PAGE_SHIFT;
 92
 93		if (!(md->attribute & EFI_MEMORY_RUNTIME))
 94			continue;
 95		if (md->virt_addr == 0 && md->phys_addr != 0) {
 96			/* no virtual mapping has been installed by the stub */
 97			break;
 98		}
 99
100		if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size)
101			continue;
102
103		/*
104		 * This entry covers the start of @in, check whether
105		 * it covers the end as well.
106		 */
107		if (md_paddr + md_size < in_paddr + in_size) {
108			pr_warn("Entry covers multiple EFI memory map regions\n");
109			return false;
110		}
111
112		if (md->type != in->type) {
113			pr_warn("Entry type deviates from EFI memory map region type\n");
114			return false;
115		}
116
117		out->virt_addr = in_paddr + (md->virt_addr - md_paddr);
118
119		return true;
120	}
121
122	pr_warn("No matching entry found in the EFI memory map\n");
123	return false;
124}
125
126/*
127 * To be called after the EFI page tables have been populated. If a memory
128 * attributes table is available, its contents will be used to update the
129 * mappings with tightened permissions as described by the table.
130 * This requires the UEFI memory map to have already been populated with
131 * virtual addresses.
132 */
133int __init efi_memattr_apply_permissions(struct mm_struct *mm,
134					 efi_memattr_perm_setter fn)
135{
136	efi_memory_attributes_table_t *tbl;
137	int i, ret;
138
139	if (tbl_size <= sizeof(*tbl))
140		return 0;
141
142	/*
143	 * We need the EFI memory map to be setup so we can use it to
144	 * lookup the virtual addresses of all entries in the  of EFI
145	 * Memory Attributes table. If it isn't available, this
146	 * function should not be called.
147	 */
148	if (WARN_ON(!efi_enabled(EFI_MEMMAP)))
149		return 0;
150
151	tbl = memremap(efi_mem_attr_table, tbl_size, MEMREMAP_WB);
152	if (!tbl) {
153		pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n",
154		       efi_mem_attr_table);
155		return -ENOMEM;
156	}
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((void *)tbl->entry + i * tbl->desc_size,
168				       &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);
178			if (ret)
179				pr_err("Error updating mappings, skipping subsequent md's\n");
180		}
181	}
182	memunmap(tbl);
183	return ret;
184}