Linux kernel mirror (for testing)
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linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * This kernel test validates architecture page table helpers and
4 * accessors and helps in verifying their continued compliance with
5 * expected generic MM semantics.
6 *
7 * Copyright (C) 2019 ARM Ltd.
8 *
9 * Author: Anshuman Khandual <anshuman.khandual@arm.com>
10 */
11#define pr_fmt(fmt) "debug_vm_pgtable: %s: " fmt, __func__
12
13#include <linux/gfp.h>
14#include <linux/highmem.h>
15#include <linux/hugetlb.h>
16#include <linux/kernel.h>
17#include <linux/kconfig.h>
18#include <linux/mm.h>
19#include <linux/mman.h>
20#include <linux/mm_types.h>
21#include <linux/module.h>
22#include <linux/pfn_t.h>
23#include <linux/printk.h>
24#include <linux/random.h>
25#include <linux/spinlock.h>
26#include <linux/swap.h>
27#include <linux/swapops.h>
28#include <linux/start_kernel.h>
29#include <linux/sched/mm.h>
30#include <asm/pgalloc.h>
31
32#define VMFLAGS (VM_READ|VM_WRITE|VM_EXEC)
33
34/*
35 * On s390 platform, the lower 4 bits are used to identify given page table
36 * entry type. But these bits might affect the ability to clear entries with
37 * pxx_clear() because of how dynamic page table folding works on s390. So
38 * while loading up the entries do not change the lower 4 bits. It does not
39 * have affect any other platform.
40 */
41#define S390_MASK_BITS 4
42#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS)
43#define RANDOM_NZVALUE GENMASK(7, 0)
44
45static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot)
46{
47 pte_t pte = pfn_pte(pfn, prot);
48
49 WARN_ON(!pte_same(pte, pte));
50 WARN_ON(!pte_young(pte_mkyoung(pte_mkold(pte))));
51 WARN_ON(!pte_dirty(pte_mkdirty(pte_mkclean(pte))));
52 WARN_ON(!pte_write(pte_mkwrite(pte_wrprotect(pte))));
53 WARN_ON(pte_young(pte_mkold(pte_mkyoung(pte))));
54 WARN_ON(pte_dirty(pte_mkclean(pte_mkdirty(pte))));
55 WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte))));
56}
57
58#ifdef CONFIG_TRANSPARENT_HUGEPAGE
59static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot)
60{
61 pmd_t pmd = pfn_pmd(pfn, prot);
62
63 if (!has_transparent_hugepage())
64 return;
65
66 WARN_ON(!pmd_same(pmd, pmd));
67 WARN_ON(!pmd_young(pmd_mkyoung(pmd_mkold(pmd))));
68 WARN_ON(!pmd_dirty(pmd_mkdirty(pmd_mkclean(pmd))));
69 WARN_ON(!pmd_write(pmd_mkwrite(pmd_wrprotect(pmd))));
70 WARN_ON(pmd_young(pmd_mkold(pmd_mkyoung(pmd))));
71 WARN_ON(pmd_dirty(pmd_mkclean(pmd_mkdirty(pmd))));
72 WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(pmd))));
73 /*
74 * A huge page does not point to next level page table
75 * entry. Hence this must qualify as pmd_bad().
76 */
77 WARN_ON(!pmd_bad(pmd_mkhuge(pmd)));
78}
79
80#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
81static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot)
82{
83 pud_t pud = pfn_pud(pfn, prot);
84
85 if (!has_transparent_hugepage())
86 return;
87
88 WARN_ON(!pud_same(pud, pud));
89 WARN_ON(!pud_young(pud_mkyoung(pud_mkold(pud))));
90 WARN_ON(!pud_write(pud_mkwrite(pud_wrprotect(pud))));
91 WARN_ON(pud_write(pud_wrprotect(pud_mkwrite(pud))));
92 WARN_ON(pud_young(pud_mkold(pud_mkyoung(pud))));
93
94 if (mm_pmd_folded(mm))
95 return;
96
97 /*
98 * A huge page does not point to next level page table
99 * entry. Hence this must qualify as pud_bad().
100 */
101 WARN_ON(!pud_bad(pud_mkhuge(pud)));
102}
103#else /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
104static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { }
105#endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
106#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
107static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) { }
108static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { }
109#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
110
111static void __init p4d_basic_tests(unsigned long pfn, pgprot_t prot)
112{
113 p4d_t p4d;
114
115 memset(&p4d, RANDOM_NZVALUE, sizeof(p4d_t));
116 WARN_ON(!p4d_same(p4d, p4d));
117}
118
119static void __init pgd_basic_tests(unsigned long pfn, pgprot_t prot)
120{
121 pgd_t pgd;
122
123 memset(&pgd, RANDOM_NZVALUE, sizeof(pgd_t));
124 WARN_ON(!pgd_same(pgd, pgd));
125}
126
127#ifndef __PAGETABLE_PUD_FOLDED
128static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp)
129{
130 pud_t pud = READ_ONCE(*pudp);
131
132 if (mm_pmd_folded(mm))
133 return;
134
135 pud = __pud(pud_val(pud) | RANDOM_ORVALUE);
136 WRITE_ONCE(*pudp, pud);
137 pud_clear(pudp);
138 pud = READ_ONCE(*pudp);
139 WARN_ON(!pud_none(pud));
140}
141
142static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
143 pmd_t *pmdp)
144{
145 pud_t pud;
146
147 if (mm_pmd_folded(mm))
148 return;
149 /*
150 * This entry points to next level page table page.
151 * Hence this must not qualify as pud_bad().
152 */
153 pmd_clear(pmdp);
154 pud_clear(pudp);
155 pud_populate(mm, pudp, pmdp);
156 pud = READ_ONCE(*pudp);
157 WARN_ON(pud_bad(pud));
158}
159#else /* !__PAGETABLE_PUD_FOLDED */
160static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp) { }
161static void __init pud_populate_tests(struct mm_struct *mm, pud_t *pudp,
162 pmd_t *pmdp)
163{
164}
165#endif /* PAGETABLE_PUD_FOLDED */
166
167#ifndef __PAGETABLE_P4D_FOLDED
168static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp)
169{
170 p4d_t p4d = READ_ONCE(*p4dp);
171
172 if (mm_pud_folded(mm))
173 return;
174
175 p4d = __p4d(p4d_val(p4d) | RANDOM_ORVALUE);
176 WRITE_ONCE(*p4dp, p4d);
177 p4d_clear(p4dp);
178 p4d = READ_ONCE(*p4dp);
179 WARN_ON(!p4d_none(p4d));
180}
181
182static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp,
183 pud_t *pudp)
184{
185 p4d_t p4d;
186
187 if (mm_pud_folded(mm))
188 return;
189
190 /*
191 * This entry points to next level page table page.
192 * Hence this must not qualify as p4d_bad().
193 */
194 pud_clear(pudp);
195 p4d_clear(p4dp);
196 p4d_populate(mm, p4dp, pudp);
197 p4d = READ_ONCE(*p4dp);
198 WARN_ON(p4d_bad(p4d));
199}
200
201static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp)
202{
203 pgd_t pgd = READ_ONCE(*pgdp);
204
205 if (mm_p4d_folded(mm))
206 return;
207
208 pgd = __pgd(pgd_val(pgd) | RANDOM_ORVALUE);
209 WRITE_ONCE(*pgdp, pgd);
210 pgd_clear(pgdp);
211 pgd = READ_ONCE(*pgdp);
212 WARN_ON(!pgd_none(pgd));
213}
214
215static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
216 p4d_t *p4dp)
217{
218 pgd_t pgd;
219
220 if (mm_p4d_folded(mm))
221 return;
222
223 /*
224 * This entry points to next level page table page.
225 * Hence this must not qualify as pgd_bad().
226 */
227 p4d_clear(p4dp);
228 pgd_clear(pgdp);
229 pgd_populate(mm, pgdp, p4dp);
230 pgd = READ_ONCE(*pgdp);
231 WARN_ON(pgd_bad(pgd));
232}
233#else /* !__PAGETABLE_P4D_FOLDED */
234static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp) { }
235static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp) { }
236static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp,
237 pud_t *pudp)
238{
239}
240static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
241 p4d_t *p4dp)
242{
243}
244#endif /* PAGETABLE_P4D_FOLDED */
245
246static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep,
247 unsigned long vaddr)
248{
249 pte_t pte = ptep_get(ptep);
250
251 pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
252 set_pte_at(mm, vaddr, ptep, pte);
253 barrier();
254 pte_clear(mm, vaddr, ptep);
255 pte = ptep_get(ptep);
256 WARN_ON(!pte_none(pte));
257}
258
259static void __init pmd_clear_tests(struct mm_struct *mm, pmd_t *pmdp)
260{
261 pmd_t pmd = READ_ONCE(*pmdp);
262
263 pmd = __pmd(pmd_val(pmd) | RANDOM_ORVALUE);
264 WRITE_ONCE(*pmdp, pmd);
265 pmd_clear(pmdp);
266 pmd = READ_ONCE(*pmdp);
267 WARN_ON(!pmd_none(pmd));
268}
269
270static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
271 pgtable_t pgtable)
272{
273 pmd_t pmd;
274
275 /*
276 * This entry points to next level page table page.
277 * Hence this must not qualify as pmd_bad().
278 */
279 pmd_clear(pmdp);
280 pmd_populate(mm, pmdp, pgtable);
281 pmd = READ_ONCE(*pmdp);
282 WARN_ON(pmd_bad(pmd));
283}
284
285static unsigned long __init get_random_vaddr(void)
286{
287 unsigned long random_vaddr, random_pages, total_user_pages;
288
289 total_user_pages = (TASK_SIZE - FIRST_USER_ADDRESS) / PAGE_SIZE;
290
291 random_pages = get_random_long() % total_user_pages;
292 random_vaddr = FIRST_USER_ADDRESS + random_pages * PAGE_SIZE;
293
294 return random_vaddr;
295}
296
297static int __init debug_vm_pgtable(void)
298{
299 struct mm_struct *mm;
300 pgd_t *pgdp;
301 p4d_t *p4dp, *saved_p4dp;
302 pud_t *pudp, *saved_pudp;
303 pmd_t *pmdp, *saved_pmdp, pmd;
304 pte_t *ptep;
305 pgtable_t saved_ptep;
306 pgprot_t prot;
307 phys_addr_t paddr;
308 unsigned long vaddr, pte_aligned, pmd_aligned;
309 unsigned long pud_aligned, p4d_aligned, pgd_aligned;
310 spinlock_t *uninitialized_var(ptl);
311
312 pr_info("Validating architecture page table helpers\n");
313 prot = vm_get_page_prot(VMFLAGS);
314 vaddr = get_random_vaddr();
315 mm = mm_alloc();
316 if (!mm) {
317 pr_err("mm_struct allocation failed\n");
318 return 1;
319 }
320
321 /*
322 * PFN for mapping at PTE level is determined from a standard kernel
323 * text symbol. But pfns for higher page table levels are derived by
324 * masking lower bits of this real pfn. These derived pfns might not
325 * exist on the platform but that does not really matter as pfn_pxx()
326 * helpers will still create appropriate entries for the test. This
327 * helps avoid large memory block allocations to be used for mapping
328 * at higher page table levels.
329 */
330 paddr = __pa_symbol(&start_kernel);
331
332 pte_aligned = (paddr & PAGE_MASK) >> PAGE_SHIFT;
333 pmd_aligned = (paddr & PMD_MASK) >> PAGE_SHIFT;
334 pud_aligned = (paddr & PUD_MASK) >> PAGE_SHIFT;
335 p4d_aligned = (paddr & P4D_MASK) >> PAGE_SHIFT;
336 pgd_aligned = (paddr & PGDIR_MASK) >> PAGE_SHIFT;
337 WARN_ON(!pfn_valid(pte_aligned));
338
339 pgdp = pgd_offset(mm, vaddr);
340 p4dp = p4d_alloc(mm, pgdp, vaddr);
341 pudp = pud_alloc(mm, p4dp, vaddr);
342 pmdp = pmd_alloc(mm, pudp, vaddr);
343 ptep = pte_alloc_map_lock(mm, pmdp, vaddr, &ptl);
344
345 /*
346 * Save all the page table page addresses as the page table
347 * entries will be used for testing with random or garbage
348 * values. These saved addresses will be used for freeing
349 * page table pages.
350 */
351 pmd = READ_ONCE(*pmdp);
352 saved_p4dp = p4d_offset(pgdp, 0UL);
353 saved_pudp = pud_offset(p4dp, 0UL);
354 saved_pmdp = pmd_offset(pudp, 0UL);
355 saved_ptep = pmd_pgtable(pmd);
356
357 pte_basic_tests(pte_aligned, prot);
358 pmd_basic_tests(pmd_aligned, prot);
359 pud_basic_tests(pud_aligned, prot);
360 p4d_basic_tests(p4d_aligned, prot);
361 pgd_basic_tests(pgd_aligned, prot);
362
363 pte_clear_tests(mm, ptep, vaddr);
364 pmd_clear_tests(mm, pmdp);
365 pud_clear_tests(mm, pudp);
366 p4d_clear_tests(mm, p4dp);
367 pgd_clear_tests(mm, pgdp);
368
369 pte_unmap_unlock(ptep, ptl);
370
371 pmd_populate_tests(mm, pmdp, saved_ptep);
372 pud_populate_tests(mm, pudp, saved_pmdp);
373 p4d_populate_tests(mm, p4dp, saved_pudp);
374 pgd_populate_tests(mm, pgdp, saved_p4dp);
375
376 p4d_free(mm, saved_p4dp);
377 pud_free(mm, saved_pudp);
378 pmd_free(mm, saved_pmdp);
379 pte_free(mm, saved_ptep);
380
381 mm_dec_nr_puds(mm);
382 mm_dec_nr_pmds(mm);
383 mm_dec_nr_ptes(mm);
384 mmdrop(mm);
385 return 0;
386}
387late_initcall(debug_vm_pgtable);