1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * VDSO implementations. 4 * 5 * Copyright (C) 2012 ARM Limited 6 * 7 * Author: Will Deacon <will.deacon@arm.com> 8 */ 9 10 #include <linux/cache.h> 11 #include <linux/clocksource.h> 12 #include <linux/elf.h> 13 #include <linux/err.h> 14 #include <linux/errno.h> 15 #include <linux/gfp.h> 16 #include <linux/kernel.h> 17 #include <linux/mm.h> 18 #include <linux/sched.h> 19 #include <linux/signal.h> 20 #include <linux/slab.h> 21 #include <linux/timekeeper_internal.h> 22 #include <linux/vmalloc.h> 23 #include <vdso/datapage.h> 24 #include <vdso/helpers.h> 25 #include <vdso/vsyscall.h> 26 27 #include <asm/cacheflush.h> 28 #include <asm/signal32.h> 29 #include <asm/vdso.h> 30 31 extern char vdso_start[], vdso_end[]; 32 #ifdef CONFIG_COMPAT_VDSO 33 extern char vdso32_start[], vdso32_end[]; 34 #endif /* CONFIG_COMPAT_VDSO */ 35 36 /* vdso_lookup arch_index */ 37 enum arch_vdso_type { 38 ARM64_VDSO = 0, 39 #ifdef CONFIG_COMPAT_VDSO 40 ARM64_VDSO32 = 1, 41 #endif /* CONFIG_COMPAT_VDSO */ 42 }; 43 #ifdef CONFIG_COMPAT_VDSO 44 #define VDSO_TYPES (ARM64_VDSO32 + 1) 45 #else 46 #define VDSO_TYPES (ARM64_VDSO + 1) 47 #endif /* CONFIG_COMPAT_VDSO */ 48 49 struct __vdso_abi { 50 const char *name; 51 const char *vdso_code_start; 52 const char *vdso_code_end; 53 unsigned long vdso_pages; 54 /* Data Mapping */ 55 struct vm_special_mapping *dm; 56 /* Code Mapping */ 57 struct vm_special_mapping *cm; 58 }; 59 60 static struct __vdso_abi vdso_lookup[VDSO_TYPES] __ro_after_init = { 61 { 62 .name = "vdso", 63 .vdso_code_start = vdso_start, 64 .vdso_code_end = vdso_end, 65 }, 66 #ifdef CONFIG_COMPAT_VDSO 67 { 68 .name = "vdso32", 69 .vdso_code_start = vdso32_start, 70 .vdso_code_end = vdso32_end, 71 }, 72 #endif /* CONFIG_COMPAT_VDSO */ 73 }; 74 75 /* 76 * The vDSO data page. 77 */ 78 static union { 79 struct vdso_data data[CS_BASES]; 80 u8 page[PAGE_SIZE]; 81 } vdso_data_store __page_aligned_data; 82 struct vdso_data *vdso_data = vdso_data_store.data; 83 84 static int __vdso_remap(enum arch_vdso_type arch_index, 85 const struct vm_special_mapping *sm, 86 struct vm_area_struct *new_vma) 87 { 88 unsigned long new_size = new_vma->vm_end - new_vma->vm_start; 89 unsigned long vdso_size = vdso_lookup[arch_index].vdso_code_end - 90 vdso_lookup[arch_index].vdso_code_start; 91 92 if (vdso_size != new_size) 93 return -EINVAL; 94 95 current->mm->context.vdso = (void *)new_vma->vm_start; 96 97 return 0; 98 } 99 100 static int __vdso_init(enum arch_vdso_type arch_index) 101 { 102 int i; 103 struct page **vdso_pagelist; 104 unsigned long pfn; 105 106 if (memcmp(vdso_lookup[arch_index].vdso_code_start, "\177ELF", 4)) { 107 pr_err("vDSO is not a valid ELF object!\n"); 108 return -EINVAL; 109 } 110 111 vdso_lookup[arch_index].vdso_pages = ( 112 vdso_lookup[arch_index].vdso_code_end - 113 vdso_lookup[arch_index].vdso_code_start) >> 114 PAGE_SHIFT; 115 116 /* Allocate the vDSO pagelist, plus a page for the data. */ 117 vdso_pagelist = kcalloc(vdso_lookup[arch_index].vdso_pages + 1, 118 sizeof(struct page *), 119 GFP_KERNEL); 120 if (vdso_pagelist == NULL) 121 return -ENOMEM; 122 123 /* Grab the vDSO data page. */ 124 vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data)); 125 126 127 /* Grab the vDSO code pages. */ 128 pfn = sym_to_pfn(vdso_lookup[arch_index].vdso_code_start); 129 130 for (i = 0; i < vdso_lookup[arch_index].vdso_pages; i++) 131 vdso_pagelist[i + 1] = pfn_to_page(pfn + i); 132 133 vdso_lookup[arch_index].dm->pages = &vdso_pagelist[0]; 134 vdso_lookup[arch_index].cm->pages = &vdso_pagelist[1]; 135 136 return 0; 137 } 138 139 static int __setup_additional_pages(enum arch_vdso_type arch_index, 140 struct mm_struct *mm, 141 struct linux_binprm *bprm, 142 int uses_interp) 143 { 144 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 145 void *ret; 146 147 vdso_text_len = vdso_lookup[arch_index].vdso_pages << PAGE_SHIFT; 148 /* Be sure to map the data page */ 149 vdso_mapping_len = vdso_text_len + PAGE_SIZE; 150 151 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 152 if (IS_ERR_VALUE(vdso_base)) { 153 ret = ERR_PTR(vdso_base); 154 goto up_fail; 155 } 156 157 ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE, 158 VM_READ|VM_MAYREAD, 159 vdso_lookup[arch_index].dm); 160 if (IS_ERR(ret)) 161 goto up_fail; 162 163 vdso_base += PAGE_SIZE; 164 mm->context.vdso = (void *)vdso_base; 165 ret = _install_special_mapping(mm, vdso_base, vdso_text_len, 166 VM_READ|VM_EXEC| 167 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 168 vdso_lookup[arch_index].cm); 169 if (IS_ERR(ret)) 170 goto up_fail; 171 172 return 0; 173 174 up_fail: 175 mm->context.vdso = NULL; 176 return PTR_ERR(ret); 177 } 178 179 #ifdef CONFIG_COMPAT 180 /* 181 * Create and map the vectors page for AArch32 tasks. 182 */ 183 #ifdef CONFIG_COMPAT_VDSO 184 static int aarch32_vdso_mremap(const struct vm_special_mapping *sm, 185 struct vm_area_struct *new_vma) 186 { 187 return __vdso_remap(ARM64_VDSO32, sm, new_vma); 188 } 189 #endif /* CONFIG_COMPAT_VDSO */ 190 191 /* 192 * aarch32_vdso_pages: 193 * 0 - kuser helpers 194 * 1 - sigreturn code 195 * or (CONFIG_COMPAT_VDSO): 196 * 0 - kuser helpers 197 * 1 - vdso data 198 * 2 - vdso code 199 */ 200 #define C_VECTORS 0 201 #ifdef CONFIG_COMPAT_VDSO 202 #define C_VVAR 1 203 #define C_VDSO 2 204 #define C_PAGES (C_VDSO + 1) 205 #else 206 #define C_SIGPAGE 1 207 #define C_PAGES (C_SIGPAGE + 1) 208 #endif /* CONFIG_COMPAT_VDSO */ 209 static struct page *aarch32_vdso_pages[C_PAGES] __ro_after_init; 210 static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = { 211 { 212 .name = "[vectors]", /* ABI */ 213 .pages = &aarch32_vdso_pages[C_VECTORS], 214 }, 215 #ifdef CONFIG_COMPAT_VDSO 216 { 217 .name = "[vvar]", 218 }, 219 { 220 .name = "[vdso]", 221 .mremap = aarch32_vdso_mremap, 222 }, 223 #else 224 { 225 .name = "[sigpage]", /* ABI */ 226 .pages = &aarch32_vdso_pages[C_SIGPAGE], 227 }, 228 #endif /* CONFIG_COMPAT_VDSO */ 229 }; 230 231 static int aarch32_alloc_kuser_vdso_page(void) 232 { 233 extern char __kuser_helper_start[], __kuser_helper_end[]; 234 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 235 unsigned long vdso_page; 236 237 if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) 238 return 0; 239 240 vdso_page = get_zeroed_page(GFP_ATOMIC); 241 if (!vdso_page) 242 return -ENOMEM; 243 244 memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start, 245 kuser_sz); 246 aarch32_vdso_pages[C_VECTORS] = virt_to_page(vdso_page); 247 flush_dcache_page(aarch32_vdso_pages[C_VECTORS]); 248 return 0; 249 } 250 251 #ifdef CONFIG_COMPAT_VDSO 252 static int __aarch32_alloc_vdso_pages(void) 253 { 254 int ret; 255 256 vdso_lookup[ARM64_VDSO32].dm = &aarch32_vdso_spec[C_VVAR]; 257 vdso_lookup[ARM64_VDSO32].cm = &aarch32_vdso_spec[C_VDSO]; 258 259 ret = __vdso_init(ARM64_VDSO32); 260 if (ret) 261 return ret; 262 263 ret = aarch32_alloc_kuser_vdso_page(); 264 if (ret) { 265 unsigned long c_vvar = 266 (unsigned long)page_to_virt(aarch32_vdso_pages[C_VVAR]); 267 unsigned long c_vdso = 268 (unsigned long)page_to_virt(aarch32_vdso_pages[C_VDSO]); 269 270 free_page(c_vvar); 271 free_page(c_vdso); 272 } 273 274 return ret; 275 } 276 #else 277 static int __aarch32_alloc_vdso_pages(void) 278 { 279 extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[]; 280 int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start; 281 unsigned long sigpage; 282 int ret; 283 284 sigpage = get_zeroed_page(GFP_ATOMIC); 285 if (!sigpage) 286 return -ENOMEM; 287 288 memcpy((void *)sigpage, __aarch32_sigret_code_start, sigret_sz); 289 aarch32_vdso_pages[C_SIGPAGE] = virt_to_page(sigpage); 290 flush_dcache_page(aarch32_vdso_pages[C_SIGPAGE]); 291 292 ret = aarch32_alloc_kuser_vdso_page(); 293 if (ret) 294 free_page(sigpage); 295 296 return ret; 297 } 298 #endif /* CONFIG_COMPAT_VDSO */ 299 300 static int __init aarch32_alloc_vdso_pages(void) 301 { 302 return __aarch32_alloc_vdso_pages(); 303 } 304 arch_initcall(aarch32_alloc_vdso_pages); 305 306 static int aarch32_kuser_helpers_setup(struct mm_struct *mm) 307 { 308 void *ret; 309 310 if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) 311 return 0; 312 313 /* 314 * Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's 315 * not safe to CoW the page containing the CPU exception vectors. 316 */ 317 ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE, 318 VM_READ | VM_EXEC | 319 VM_MAYREAD | VM_MAYEXEC, 320 &aarch32_vdso_spec[C_VECTORS]); 321 322 return PTR_ERR_OR_ZERO(ret); 323 } 324 325 #ifndef CONFIG_COMPAT_VDSO 326 static int aarch32_sigreturn_setup(struct mm_struct *mm) 327 { 328 unsigned long addr; 329 void *ret; 330 331 addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); 332 if (IS_ERR_VALUE(addr)) { 333 ret = ERR_PTR(addr); 334 goto out; 335 } 336 337 /* 338 * VM_MAYWRITE is required to allow gdb to Copy-on-Write and 339 * set breakpoints. 340 */ 341 ret = _install_special_mapping(mm, addr, PAGE_SIZE, 342 VM_READ | VM_EXEC | VM_MAYREAD | 343 VM_MAYWRITE | VM_MAYEXEC, 344 &aarch32_vdso_spec[C_SIGPAGE]); 345 if (IS_ERR(ret)) 346 goto out; 347 348 mm->context.vdso = (void *)addr; 349 350 out: 351 return PTR_ERR_OR_ZERO(ret); 352 } 353 #endif /* !CONFIG_COMPAT_VDSO */ 354 355 int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 356 { 357 struct mm_struct *mm = current->mm; 358 int ret; 359 360 if (down_write_killable(&mm->mmap_sem)) 361 return -EINTR; 362 363 ret = aarch32_kuser_helpers_setup(mm); 364 if (ret) 365 goto out; 366 367 #ifdef CONFIG_COMPAT_VDSO 368 ret = __setup_additional_pages(ARM64_VDSO32, 369 mm, 370 bprm, 371 uses_interp); 372 #else 373 ret = aarch32_sigreturn_setup(mm); 374 #endif /* CONFIG_COMPAT_VDSO */ 375 376 out: 377 up_write(&mm->mmap_sem); 378 return ret; 379 } 380 #endif /* CONFIG_COMPAT */ 381 382 static int vdso_mremap(const struct vm_special_mapping *sm, 383 struct vm_area_struct *new_vma) 384 { 385 return __vdso_remap(ARM64_VDSO, sm, new_vma); 386 } 387 388 /* 389 * aarch64_vdso_pages: 390 * 0 - vvar 391 * 1 - vdso 392 */ 393 #define A_VVAR 0 394 #define A_VDSO 1 395 #define A_PAGES (A_VDSO + 1) 396 static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = { 397 { 398 .name = "[vvar]", 399 }, 400 { 401 .name = "[vdso]", 402 .mremap = vdso_mremap, 403 }, 404 }; 405 406 static int __init vdso_init(void) 407 { 408 vdso_lookup[ARM64_VDSO].dm = &vdso_spec[A_VVAR]; 409 vdso_lookup[ARM64_VDSO].cm = &vdso_spec[A_VDSO]; 410 411 return __vdso_init(ARM64_VDSO); 412 } 413 arch_initcall(vdso_init); 414 415 int arch_setup_additional_pages(struct linux_binprm *bprm, 416 int uses_interp) 417 { 418 struct mm_struct *mm = current->mm; 419 int ret; 420 421 if (down_write_killable(&mm->mmap_sem)) 422 return -EINTR; 423 424 ret = __setup_additional_pages(ARM64_VDSO, 425 mm, 426 bprm, 427 uses_interp); 428 429 up_write(&mm->mmap_sem); 430 431 return ret; 432 } 433