1/*
 2 * Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org>
 3 *
 4 * This program is free software; you can redistribute it and/or modify
 5 * it under the terms of the GNU General Public License version 2 as
 6 * published by the Free Software Foundation.
 7 */
 8
 9#include <linux/efi.h>
10#include <asm/efi.h>
11#include <asm/mach/map.h>
12#include <asm/mmu_context.h>
13
14static int __init set_permissions(pte_t *ptep, pgtable_t token,
15				  unsigned long addr, void *data)
16{
17	efi_memory_desc_t *md = data;
18	pte_t pte = *ptep;
19
20	if (md->attribute & EFI_MEMORY_RO)
21		pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY));
22	if (md->attribute & EFI_MEMORY_XP)
23		pte = set_pte_bit(pte, __pgprot(L_PTE_XN));
24	set_pte_ext(ptep, pte, PTE_EXT_NG);
25	return 0;
26}
27
28int __init efi_set_mapping_permissions(struct mm_struct *mm,
29				       efi_memory_desc_t *md)
30{
31	unsigned long base, size;
32
33	base = md->virt_addr;
34	size = md->num_pages << EFI_PAGE_SHIFT;
35
36	/*
37	 * We can only use apply_to_page_range() if we can guarantee that the
38	 * entire region was mapped using pages. This should be the case if the
39	 * region does not cover any naturally aligned SECTION_SIZE sized
40	 * blocks.
41	 */
42	if (round_down(base + size, SECTION_SIZE) <
43	    round_up(base, SECTION_SIZE) + SECTION_SIZE)
44		return apply_to_page_range(mm, base, size, set_permissions, md);
45
46	return 0;
47}
48
49int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md)
50{
51	struct map_desc desc = {
52		.virtual	= md->virt_addr,
53		.pfn		= __phys_to_pfn(md->phys_addr),
54		.length		= md->num_pages * EFI_PAGE_SIZE,
55	};
56
57	/*
58	 * Order is important here: memory regions may have all of the
59	 * bits below set (and usually do), so we check them in order of
60	 * preference.
61	 */
62	if (md->attribute & EFI_MEMORY_WB)
63		desc.type = MT_MEMORY_RWX;
64	else if (md->attribute & EFI_MEMORY_WT)
65		desc.type = MT_MEMORY_RWX_NONCACHED;
66	else if (md->attribute & EFI_MEMORY_WC)
67		desc.type = MT_DEVICE_WC;
68	else
69		desc.type = MT_DEVICE;
70
71	create_mapping_late(mm, &desc, true);
72
73	/*
74	 * If stricter permissions were specified, apply them now.
75	 */
76	if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))
77		return efi_set_mapping_permissions(mm, md);
78	return 0;
79}