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 45 static 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 59 static 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 81 static 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 */ 104 static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { } 105 #endif /* CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */ 106 #else /* !CONFIG_TRANSPARENT_HUGEPAGE */ 107 static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot) { } 108 static void __init pud_basic_tests(unsigned long pfn, pgprot_t prot) { } 109 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 110 111 static 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 } 118 119 static 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 128 static 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 } 141 142 static 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 */ 160 static void __init pud_clear_tests(struct mm_struct *mm, pud_t *pudp) { } 161 static 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 168 static 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 } 181 182 static 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 } 200 201 static 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 } 214 215 static 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 */ 234 static void __init p4d_clear_tests(struct mm_struct *mm, p4d_t *p4dp) { } 235 static void __init pgd_clear_tests(struct mm_struct *mm, pgd_t *pgdp) { } 236 static void __init p4d_populate_tests(struct mm_struct *mm, p4d_t *p4dp, 237 pud_t *pudp) 238 { 239 } 240 static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp, 241 p4d_t *p4dp) 242 { 243 } 244 #endif /* PAGETABLE_P4D_FOLDED */ 245 246 static 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 } 258 259 static 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 } 269 270 static 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 } 284 285 static 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 } 296 297 static 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 } 387 late_initcall(debug_vm_pgtable); 388