1#include <linux/module.h>
2#include <linux/kernel.h>
3#include <linux/slab.h>
4
5#include <asm/cputype.h>
6#include <asm/idmap.h>
7#include <asm/pgalloc.h>
8#include <asm/pgtable.h>
9#include <asm/sections.h>
10#include <asm/system_info.h>
11
12/*
13 * Note: accesses outside of the kernel image and the identity map area
14 * are not supported on any CPU using the idmap tables as its current
15 * page tables.
16 */
17pgd_t *idmap_pgd;
18phys_addr_t (*arch_virt_to_idmap) (unsigned long x);
19
20#ifdef CONFIG_ARM_LPAE
21static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
22	unsigned long prot)
23{
24	pmd_t *pmd;
25	unsigned long next;
26
27	if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
28		pmd = pmd_alloc_one(&init_mm, addr);
29		if (!pmd) {
30			pr_warn("Failed to allocate identity pmd.\n");
31			return;
32		}
33		/*
34		 * Copy the original PMD to ensure that the PMD entries for
35		 * the kernel image are preserved.
36		 */
37		if (!pud_none(*pud))
38			memcpy(pmd, pmd_offset(pud, 0),
39			       PTRS_PER_PMD * sizeof(pmd_t));
40		pud_populate(&init_mm, pud, pmd);
41		pmd += pmd_index(addr);
42	} else
43		pmd = pmd_offset(pud, addr);
44
45	do {
46		next = pmd_addr_end(addr, end);
47		*pmd = __pmd((addr & PMD_MASK) | prot);
48		flush_pmd_entry(pmd);
49	} while (pmd++, addr = next, addr != end);
50}
51#else	/* !CONFIG_ARM_LPAE */
52static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
53	unsigned long prot)
54{
55	pmd_t *pmd = pmd_offset(pud, addr);
56
57	addr = (addr & PMD_MASK) | prot;
58	pmd[0] = __pmd(addr);
59	addr += SECTION_SIZE;
60	pmd[1] = __pmd(addr);
61	flush_pmd_entry(pmd);
62}
63#endif	/* CONFIG_ARM_LPAE */
64
65static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
66	unsigned long prot)
67{
68	pud_t *pud = pud_offset(pgd, addr);
69	unsigned long next;
70
71	do {
72		next = pud_addr_end(addr, end);
73		idmap_add_pmd(pud, addr, next, prot);
74	} while (pud++, addr = next, addr != end);
75}
76
77static void identity_mapping_add(pgd_t *pgd, const char *text_start,
78				 const char *text_end, unsigned long prot)
79{
80	unsigned long addr, end;
81	unsigned long next;
82
83	addr = virt_to_idmap(text_start);
84	end = virt_to_idmap(text_end);
85	pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);
86
87	prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
88
89	if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
90		prot |= PMD_BIT4;
91
92	pgd += pgd_index(addr);
93	do {
94		next = pgd_addr_end(addr, end);
95		idmap_add_pud(pgd, addr, next, prot);
96	} while (pgd++, addr = next, addr != end);
97}
98
99extern char  __idmap_text_start[], __idmap_text_end[];
100
101static int __init init_static_idmap(void)
102{
103	idmap_pgd = pgd_alloc(&init_mm);
104	if (!idmap_pgd)
105		return -ENOMEM;
106
107	identity_mapping_add(idmap_pgd, __idmap_text_start,
108			     __idmap_text_end, 0);
109
110	/* Flush L1 for the hardware to see this page table content */
111	flush_cache_louis();
112
113	return 0;
114}
115early_initcall(init_static_idmap);
116
117/*
118 * In order to soft-boot, we need to switch to a 1:1 mapping for the
119 * cpu_reset functions. This will then ensure that we have predictable
120 * results when turning off the mmu.
121 */
122void setup_mm_for_reboot(void)
123{
124	/* Switch to the identity mapping. */
125	cpu_switch_mm(idmap_pgd, &init_mm);
126	local_flush_bp_all();
127
128#ifdef CONFIG_CPU_HAS_ASID
129	/*
130	 * We don't have a clean ASID for the identity mapping, which
131	 * may clash with virtual addresses of the previous page tables
132	 * and therefore potentially in the TLB.
133	 */
134	local_flush_tlb_all();
135#endif
136}
137