mm/page_table_check: remove unused parameter in [__]page_table_check_pmd_set
[platform/kernel/linux-starfive.git] / mm / page_table_check.c
1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4  * Copyright (c) 2021, Google LLC.
5  * Pasha Tatashin <pasha.tatashin@soleen.com>
6  */
7 #include <linux/kstrtox.h>
8 #include <linux/mm.h>
9 #include <linux/page_table_check.h>
10
11 #undef pr_fmt
12 #define pr_fmt(fmt)     "page_table_check: " fmt
13
14 struct page_table_check {
15         atomic_t anon_map_count;
16         atomic_t file_map_count;
17 };
18
19 static bool __page_table_check_enabled __initdata =
20                                 IS_ENABLED(CONFIG_PAGE_TABLE_CHECK_ENFORCED);
21
22 DEFINE_STATIC_KEY_TRUE(page_table_check_disabled);
23 EXPORT_SYMBOL(page_table_check_disabled);
24
25 static int __init early_page_table_check_param(char *buf)
26 {
27         return kstrtobool(buf, &__page_table_check_enabled);
28 }
29
30 early_param("page_table_check", early_page_table_check_param);
31
32 static bool __init need_page_table_check(void)
33 {
34         return __page_table_check_enabled;
35 }
36
37 static void __init init_page_table_check(void)
38 {
39         if (!__page_table_check_enabled)
40                 return;
41         static_branch_disable(&page_table_check_disabled);
42 }
43
44 struct page_ext_operations page_table_check_ops = {
45         .size = sizeof(struct page_table_check),
46         .need = need_page_table_check,
47         .init = init_page_table_check,
48         .need_shared_flags = false,
49 };
50
51 static struct page_table_check *get_page_table_check(struct page_ext *page_ext)
52 {
53         BUG_ON(!page_ext);
54         return (void *)(page_ext) + page_table_check_ops.offset;
55 }
56
57 /*
58  * An entry is removed from the page table, decrement the counters for that page
59  * verify that it is of correct type and counters do not become negative.
60  */
61 static void page_table_check_clear(unsigned long pfn, unsigned long pgcnt)
62 {
63         struct page_ext *page_ext;
64         struct page *page;
65         unsigned long i;
66         bool anon;
67
68         if (!pfn_valid(pfn))
69                 return;
70
71         page = pfn_to_page(pfn);
72         page_ext = page_ext_get(page);
73
74         BUG_ON(PageSlab(page));
75         anon = PageAnon(page);
76
77         for (i = 0; i < pgcnt; i++) {
78                 struct page_table_check *ptc = get_page_table_check(page_ext);
79
80                 if (anon) {
81                         BUG_ON(atomic_read(&ptc->file_map_count));
82                         BUG_ON(atomic_dec_return(&ptc->anon_map_count) < 0);
83                 } else {
84                         BUG_ON(atomic_read(&ptc->anon_map_count));
85                         BUG_ON(atomic_dec_return(&ptc->file_map_count) < 0);
86                 }
87                 page_ext = page_ext_next(page_ext);
88         }
89         page_ext_put(page_ext);
90 }
91
92 /*
93  * A new entry is added to the page table, increment the counters for that page
94  * verify that it is of correct type and is not being mapped with a different
95  * type to a different process.
96  */
97 static void page_table_check_set(unsigned long pfn, unsigned long pgcnt,
98                                  bool rw)
99 {
100         struct page_ext *page_ext;
101         struct page *page;
102         unsigned long i;
103         bool anon;
104
105         if (!pfn_valid(pfn))
106                 return;
107
108         page = pfn_to_page(pfn);
109         page_ext = page_ext_get(page);
110
111         BUG_ON(PageSlab(page));
112         anon = PageAnon(page);
113
114         for (i = 0; i < pgcnt; i++) {
115                 struct page_table_check *ptc = get_page_table_check(page_ext);
116
117                 if (anon) {
118                         BUG_ON(atomic_read(&ptc->file_map_count));
119                         BUG_ON(atomic_inc_return(&ptc->anon_map_count) > 1 && rw);
120                 } else {
121                         BUG_ON(atomic_read(&ptc->anon_map_count));
122                         BUG_ON(atomic_inc_return(&ptc->file_map_count) < 0);
123                 }
124                 page_ext = page_ext_next(page_ext);
125         }
126         page_ext_put(page_ext);
127 }
128
129 /*
130  * page is on free list, or is being allocated, verify that counters are zeroes
131  * crash if they are not.
132  */
133 void __page_table_check_zero(struct page *page, unsigned int order)
134 {
135         struct page_ext *page_ext;
136         unsigned long i;
137
138         BUG_ON(PageSlab(page));
139
140         page_ext = page_ext_get(page);
141         BUG_ON(!page_ext);
142         for (i = 0; i < (1ul << order); i++) {
143                 struct page_table_check *ptc = get_page_table_check(page_ext);
144
145                 BUG_ON(atomic_read(&ptc->anon_map_count));
146                 BUG_ON(atomic_read(&ptc->file_map_count));
147                 page_ext = page_ext_next(page_ext);
148         }
149         page_ext_put(page_ext);
150 }
151
152 void __page_table_check_pte_clear(struct mm_struct *mm, pte_t pte)
153 {
154         if (&init_mm == mm)
155                 return;
156
157         if (pte_user_accessible_page(pte)) {
158                 page_table_check_clear(pte_pfn(pte), PAGE_SIZE >> PAGE_SHIFT);
159         }
160 }
161 EXPORT_SYMBOL(__page_table_check_pte_clear);
162
163 void __page_table_check_pmd_clear(struct mm_struct *mm, pmd_t pmd)
164 {
165         if (&init_mm == mm)
166                 return;
167
168         if (pmd_user_accessible_page(pmd)) {
169                 page_table_check_clear(pmd_pfn(pmd), PMD_SIZE >> PAGE_SHIFT);
170         }
171 }
172 EXPORT_SYMBOL(__page_table_check_pmd_clear);
173
174 void __page_table_check_pud_clear(struct mm_struct *mm, pud_t pud)
175 {
176         if (&init_mm == mm)
177                 return;
178
179         if (pud_user_accessible_page(pud)) {
180                 page_table_check_clear(pud_pfn(pud), PUD_SIZE >> PAGE_SHIFT);
181         }
182 }
183 EXPORT_SYMBOL(__page_table_check_pud_clear);
184
185 void __page_table_check_pte_set(struct mm_struct *mm, pte_t *ptep, pte_t pte)
186 {
187         if (&init_mm == mm)
188                 return;
189
190         __page_table_check_pte_clear(mm, ptep_get(ptep));
191         if (pte_user_accessible_page(pte)) {
192                 page_table_check_set(pte_pfn(pte), PAGE_SIZE >> PAGE_SHIFT,
193                                      pte_write(pte));
194         }
195 }
196 EXPORT_SYMBOL(__page_table_check_pte_set);
197
198 void __page_table_check_pmd_set(struct mm_struct *mm, pmd_t *pmdp, pmd_t pmd)
199 {
200         if (&init_mm == mm)
201                 return;
202
203         __page_table_check_pmd_clear(mm, *pmdp);
204         if (pmd_user_accessible_page(pmd)) {
205                 page_table_check_set(pmd_pfn(pmd), PMD_SIZE >> PAGE_SHIFT,
206                                      pmd_write(pmd));
207         }
208 }
209 EXPORT_SYMBOL(__page_table_check_pmd_set);
210
211 void __page_table_check_pud_set(struct mm_struct *mm, unsigned long addr,
212                                 pud_t *pudp, pud_t pud)
213 {
214         if (&init_mm == mm)
215                 return;
216
217         __page_table_check_pud_clear(mm, *pudp);
218         if (pud_user_accessible_page(pud)) {
219                 page_table_check_set(pud_pfn(pud), PUD_SIZE >> PAGE_SHIFT,
220                                      pud_write(pud));
221         }
222 }
223 EXPORT_SYMBOL(__page_table_check_pud_set);
224
225 void __page_table_check_pte_clear_range(struct mm_struct *mm,
226                                         unsigned long addr,
227                                         pmd_t pmd)
228 {
229         if (&init_mm == mm)
230                 return;
231
232         if (!pmd_bad(pmd) && !pmd_leaf(pmd)) {
233                 pte_t *ptep = pte_offset_map(&pmd, addr);
234                 unsigned long i;
235
236                 if (WARN_ON(!ptep))
237                         return;
238                 for (i = 0; i < PTRS_PER_PTE; i++) {
239                         __page_table_check_pte_clear(mm, ptep_get(ptep));
240                         addr += PAGE_SIZE;
241                         ptep++;
242                 }
243                 pte_unmap(ptep - PTRS_PER_PTE);
244         }
245 }