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1// SPDX-License-Identifier: GPL-2.0
2#include <linux/module.h>
3#include <linux/kernel.h>
4#include <linux/slab.h>
5#include <linux/mm_types.h>
6
7#include <asm/cputype.h>
8#include <asm/idmap.h>
9#include <asm/pgalloc.h>
10#include <asm/pgtable.h>
11#include <asm/sections.h>
12#include <asm/system_info.h>
13
14/*
15 * Note: accesses outside of the kernel image and the identity map area
16 * are not supported on any CPU using the idmap tables as its current
17 * page tables.
18 */
19pgd_t *idmap_pgd __ro_after_init;
20long long arch_phys_to_idmap_offset __ro_after_init;
21
22#ifdef CONFIG_ARM_LPAE
23static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
24 unsigned long prot)
25{
26 pmd_t *pmd;
27 unsigned long next;
28
29 if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
30 pmd = pmd_alloc_one(&init_mm, addr);
31 if (!pmd) {
32 pr_warn("Failed to allocate identity pmd.\n");
33 return;
34 }
35 /*
36 * Copy the original PMD to ensure that the PMD entries for
37 * the kernel image are preserved.
38 */
39 if (!pud_none(*pud))
40 memcpy(pmd, pmd_offset(pud, 0),
41 PTRS_PER_PMD * sizeof(pmd_t));
42 pud_populate(&init_mm, pud, pmd);
43 pmd += pmd_index(addr);
44 } else
45 pmd = pmd_offset(pud, addr);
46
47 do {
48 next = pmd_addr_end(addr, end);
49 *pmd = __pmd((addr & PMD_MASK) | prot);
50 flush_pmd_entry(pmd);
51 } while (pmd++, addr = next, addr != end);
52}
53#else /* !CONFIG_ARM_LPAE */
54static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
55 unsigned long prot)
56{
57 pmd_t *pmd = pmd_offset(pud, addr);
58
59 addr = (addr & PMD_MASK) | prot;
60 pmd[0] = __pmd(addr);
61 addr += SECTION_SIZE;
62 pmd[1] = __pmd(addr);
63 flush_pmd_entry(pmd);
64}
65#endif /* CONFIG_ARM_LPAE */
66
67static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
68 unsigned long prot)
69{
70 pud_t *pud = pud_offset(pgd, addr);
71 unsigned long next;
72
73 do {
74 next = pud_addr_end(addr, end);
75 idmap_add_pmd(pud, addr, next, prot);
76 } while (pud++, addr = next, addr != end);
77}
78
79static void identity_mapping_add(pgd_t *pgd, const char *text_start,
80 const char *text_end, unsigned long prot)
81{
82 unsigned long addr, end;
83 unsigned long next;
84
85 addr = virt_to_idmap(text_start);
86 end = virt_to_idmap(text_end);
87 pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);
88
89 prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
90
91 if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale_family())
92 prot |= PMD_BIT4;
93
94 pgd += pgd_index(addr);
95 do {
96 next = pgd_addr_end(addr, end);
97 idmap_add_pud(pgd, addr, next, prot);
98 } while (pgd++, addr = next, addr != end);
99}
100
101extern char __idmap_text_start[], __idmap_text_end[];
102
103static int __init init_static_idmap(void)
104{
105 idmap_pgd = pgd_alloc(&init_mm);
106 if (!idmap_pgd)
107 return -ENOMEM;
108
109 identity_mapping_add(idmap_pgd, __idmap_text_start,
110 __idmap_text_end, 0);
111
112 /* Flush L1 for the hardware to see this page table content */
113 flush_cache_louis();
114
115 return 0;
116}
117early_initcall(init_static_idmap);
118
119/*
120 * In order to soft-boot, we need to switch to a 1:1 mapping for the
121 * cpu_reset functions. This will then ensure that we have predictable
122 * results when turning off the mmu.
123 */
124void setup_mm_for_reboot(void)
125{
126 /* Switch to the identity mapping. */
127 cpu_switch_mm(idmap_pgd, &init_mm);
128 local_flush_bp_all();
129
130#ifdef CONFIG_CPU_HAS_ASID
131 /*
132 * We don't have a clean ASID for the identity mapping, which
133 * may clash with virtual addresses of the previous page tables
134 * and therefore potentially in the TLB.
135 */
136 local_flush_tlb_all();
137#endif
138}
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
12pgd_t *idmap_pgd;
13phys_addr_t (*arch_virt_to_idmap) (unsigned long x);
14
15#ifdef CONFIG_ARM_LPAE
16static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
17 unsigned long prot)
18{
19 pmd_t *pmd;
20 unsigned long next;
21
22 if (pud_none_or_clear_bad(pud) || (pud_val(*pud) & L_PGD_SWAPPER)) {
23 pmd = pmd_alloc_one(&init_mm, addr);
24 if (!pmd) {
25 pr_warning("Failed to allocate identity pmd.\n");
26 return;
27 }
28 pud_populate(&init_mm, pud, pmd);
29 pmd += pmd_index(addr);
30 } else
31 pmd = pmd_offset(pud, addr);
32
33 do {
34 next = pmd_addr_end(addr, end);
35 *pmd = __pmd((addr & PMD_MASK) | prot);
36 flush_pmd_entry(pmd);
37 } while (pmd++, addr = next, addr != end);
38}
39#else /* !CONFIG_ARM_LPAE */
40static void idmap_add_pmd(pud_t *pud, unsigned long addr, unsigned long end,
41 unsigned long prot)
42{
43 pmd_t *pmd = pmd_offset(pud, addr);
44
45 addr = (addr & PMD_MASK) | prot;
46 pmd[0] = __pmd(addr);
47 addr += SECTION_SIZE;
48 pmd[1] = __pmd(addr);
49 flush_pmd_entry(pmd);
50}
51#endif /* CONFIG_ARM_LPAE */
52
53static void idmap_add_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
54 unsigned long prot)
55{
56 pud_t *pud = pud_offset(pgd, addr);
57 unsigned long next;
58
59 do {
60 next = pud_addr_end(addr, end);
61 idmap_add_pmd(pud, addr, next, prot);
62 } while (pud++, addr = next, addr != end);
63}
64
65static void identity_mapping_add(pgd_t *pgd, const char *text_start,
66 const char *text_end, unsigned long prot)
67{
68 unsigned long addr, end;
69 unsigned long next;
70
71 addr = virt_to_idmap(text_start);
72 end = virt_to_idmap(text_end);
73 pr_info("Setting up static identity map for 0x%lx - 0x%lx\n", addr, end);
74
75 prot |= PMD_TYPE_SECT | PMD_SECT_AP_WRITE | PMD_SECT_AF;
76
77 if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
78 prot |= PMD_BIT4;
79
80 pgd += pgd_index(addr);
81 do {
82 next = pgd_addr_end(addr, end);
83 idmap_add_pud(pgd, addr, next, prot);
84 } while (pgd++, addr = next, addr != end);
85}
86
87extern char __idmap_text_start[], __idmap_text_end[];
88
89static int __init init_static_idmap(void)
90{
91 idmap_pgd = pgd_alloc(&init_mm);
92 if (!idmap_pgd)
93 return -ENOMEM;
94
95 identity_mapping_add(idmap_pgd, __idmap_text_start,
96 __idmap_text_end, 0);
97
98 /* Flush L1 for the hardware to see this page table content */
99 flush_cache_louis();
100
101 return 0;
102}
103early_initcall(init_static_idmap);
104
105/*
106 * In order to soft-boot, we need to switch to a 1:1 mapping for the
107 * cpu_reset functions. This will then ensure that we have predictable
108 * results when turning off the mmu.
109 */
110void setup_mm_for_reboot(void)
111{
112 /* Switch to the identity mapping. */
113 cpu_switch_mm(idmap_pgd, &init_mm);
114 local_flush_bp_all();
115
116#ifdef CONFIG_CPU_HAS_ASID
117 /*
118 * We don't have a clean ASID for the identity mapping, which
119 * may clash with virtual addresses of the previous page tables
120 * and therefore potentially in the TLB.
121 */
122 local_flush_tlb_all();
123#endif
124}