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 enum vdso_abi { 37 VDSO_ABI_AA64, 38 #ifdef CONFIG_COMPAT_VDSO 39 VDSO_ABI_AA32, 40 #endif /* CONFIG_COMPAT_VDSO */ 41 }; 42 43 struct vdso_abi_info { 44 const char *name; 45 const char *vdso_code_start; 46 const char *vdso_code_end; 47 unsigned long vdso_pages; 48 /* Data Mapping */ 49 struct vm_special_mapping *dm; 50 /* Code Mapping */ 51 struct vm_special_mapping *cm; 52 }; 53 54 static struct vdso_abi_info vdso_info[] __ro_after_init = { 55 [VDSO_ABI_AA64] = { 56 .name = "vdso", 57 .vdso_code_start = vdso_start, 58 .vdso_code_end = vdso_end, 59 }, 60 #ifdef CONFIG_COMPAT_VDSO 61 [VDSO_ABI_AA32] = { 62 .name = "vdso32", 63 .vdso_code_start = vdso32_start, 64 .vdso_code_end = vdso32_end, 65 }, 66 #endif /* CONFIG_COMPAT_VDSO */ 67 }; 68 69 /* 70 * The vDSO data page. 71 */ 72 static union { 73 struct vdso_data data[CS_BASES]; 74 u8 page[PAGE_SIZE]; 75 } vdso_data_store __page_aligned_data; 76 struct vdso_data *vdso_data = vdso_data_store.data; 77 78 static int __vdso_remap(enum vdso_abi abi, 79 const struct vm_special_mapping *sm, 80 struct vm_area_struct *new_vma) 81 { 82 unsigned long new_size = new_vma->vm_end - new_vma->vm_start; 83 unsigned long vdso_size = vdso_info[abi].vdso_code_end - 84 vdso_info[abi].vdso_code_start; 85 86 if (vdso_size != new_size) 87 return -EINVAL; 88 89 current->mm->context.vdso = (void *)new_vma->vm_start; 90 91 return 0; 92 } 93 94 static int __vdso_init(enum vdso_abi abi) 95 { 96 int i; 97 struct page **vdso_pagelist; 98 unsigned long pfn; 99 100 if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4)) { 101 pr_err("vDSO is not a valid ELF object!\n"); 102 return -EINVAL; 103 } 104 105 vdso_info[abi].vdso_pages = ( 106 vdso_info[abi].vdso_code_end - 107 vdso_info[abi].vdso_code_start) >> 108 PAGE_SHIFT; 109 110 /* Allocate the vDSO pagelist, plus a page for the data. */ 111 vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages + 1, 112 sizeof(struct page *), 113 GFP_KERNEL); 114 if (vdso_pagelist == NULL) 115 return -ENOMEM; 116 117 /* Grab the vDSO data page. */ 118 vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data)); 119 120 121 /* Grab the vDSO code pages. */ 122 pfn = sym_to_pfn(vdso_info[abi].vdso_code_start); 123 124 for (i = 0; i < vdso_info[abi].vdso_pages; i++) 125 vdso_pagelist[i + 1] = pfn_to_page(pfn + i); 126 127 vdso_info[abi].dm->pages = &vdso_pagelist[0]; 128 vdso_info[abi].cm->pages = &vdso_pagelist[1]; 129 130 return 0; 131 } 132 133 static int __setup_additional_pages(enum vdso_abi abi, 134 struct mm_struct *mm, 135 struct linux_binprm *bprm, 136 int uses_interp) 137 { 138 unsigned long vdso_base, vdso_text_len, vdso_mapping_len; 139 unsigned long gp_flags = 0; 140 void *ret; 141 142 vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT; 143 /* Be sure to map the data page */ 144 vdso_mapping_len = vdso_text_len + PAGE_SIZE; 145 146 vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0); 147 if (IS_ERR_VALUE(vdso_base)) { 148 ret = ERR_PTR(vdso_base); 149 goto up_fail; 150 } 151 152 ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE, 153 VM_READ|VM_MAYREAD, 154 vdso_info[abi].dm); 155 if (IS_ERR(ret)) 156 goto up_fail; 157 158 if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) && system_supports_bti()) 159 gp_flags = VM_ARM64_BTI; 160 161 vdso_base += PAGE_SIZE; 162 mm->context.vdso = (void *)vdso_base; 163 ret = _install_special_mapping(mm, vdso_base, vdso_text_len, 164 VM_READ|VM_EXEC|gp_flags| 165 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, 166 vdso_info[abi].cm); 167 if (IS_ERR(ret)) 168 goto up_fail; 169 170 return 0; 171 172 up_fail: 173 mm->context.vdso = NULL; 174 return PTR_ERR(ret); 175 } 176 177 #ifdef CONFIG_COMPAT 178 /* 179 * Create and map the vectors page for AArch32 tasks. 180 */ 181 #ifdef CONFIG_COMPAT_VDSO 182 static int aarch32_vdso_mremap(const struct vm_special_mapping *sm, 183 struct vm_area_struct *new_vma) 184 { 185 return __vdso_remap(VDSO_ABI_AA32, sm, new_vma); 186 } 187 #endif /* CONFIG_COMPAT_VDSO */ 188 189 enum aarch32_map { 190 AA32_MAP_VECTORS, /* kuser helpers */ 191 #ifdef CONFIG_COMPAT_VDSO 192 AA32_MAP_VVAR, 193 AA32_MAP_VDSO, 194 #else 195 AA32_MAP_SIGPAGE 196 #endif 197 }; 198 199 static struct page *aarch32_vectors_page __ro_after_init; 200 #ifndef CONFIG_COMPAT_VDSO 201 static struct page *aarch32_sig_page __ro_after_init; 202 #endif 203 204 static struct vm_special_mapping aarch32_vdso_maps[] = { 205 [AA32_MAP_VECTORS] = { 206 .name = "[vectors]", /* ABI */ 207 .pages = &aarch32_vectors_page, 208 }, 209 #ifdef CONFIG_COMPAT_VDSO 210 [AA32_MAP_VVAR] = { 211 .name = "[vvar]", 212 }, 213 [AA32_MAP_VDSO] = { 214 .name = "[vdso]", 215 .mremap = aarch32_vdso_mremap, 216 }, 217 #else 218 [AA32_MAP_SIGPAGE] = { 219 .name = "[sigpage]", /* ABI */ 220 .pages = &aarch32_sig_page, 221 }, 222 #endif /* CONFIG_COMPAT_VDSO */ 223 }; 224 225 static int aarch32_alloc_kuser_vdso_page(void) 226 { 227 extern char __kuser_helper_start[], __kuser_helper_end[]; 228 int kuser_sz = __kuser_helper_end - __kuser_helper_start; 229 unsigned long vdso_page; 230 231 if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) 232 return 0; 233 234 vdso_page = get_zeroed_page(GFP_ATOMIC); 235 if (!vdso_page) 236 return -ENOMEM; 237 238 memcpy((void *)(vdso_page + 0x1000 - kuser_sz), __kuser_helper_start, 239 kuser_sz); 240 aarch32_vectors_page = virt_to_page(vdso_page); 241 flush_dcache_page(aarch32_vectors_page); 242 return 0; 243 } 244 245 #ifdef CONFIG_COMPAT_VDSO 246 static int __aarch32_alloc_vdso_pages(void) 247 { 248 int ret; 249 250 vdso_info[VDSO_ABI_AA32].dm = &aarch32_vdso_maps[AA32_MAP_VVAR]; 251 vdso_info[VDSO_ABI_AA32].cm = &aarch32_vdso_maps[AA32_MAP_VDSO]; 252 253 ret = __vdso_init(VDSO_ABI_AA32); 254 if (ret) 255 return ret; 256 257 return aarch32_alloc_kuser_vdso_page(); 258 } 259 #else 260 static int __aarch32_alloc_vdso_pages(void) 261 { 262 extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[]; 263 int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start; 264 unsigned long sigpage; 265 int ret; 266 267 sigpage = get_zeroed_page(GFP_ATOMIC); 268 if (!sigpage) 269 return -ENOMEM; 270 271 memcpy((void *)sigpage, __aarch32_sigret_code_start, sigret_sz); 272 aarch32_sig_page = virt_to_page(sigpage); 273 flush_dcache_page(aarch32_sig_page); 274 275 ret = aarch32_alloc_kuser_vdso_page(); 276 if (ret) 277 free_page(sigpage); 278 279 return ret; 280 } 281 #endif /* CONFIG_COMPAT_VDSO */ 282 283 static int __init aarch32_alloc_vdso_pages(void) 284 { 285 return __aarch32_alloc_vdso_pages(); 286 } 287 arch_initcall(aarch32_alloc_vdso_pages); 288 289 static int aarch32_kuser_helpers_setup(struct mm_struct *mm) 290 { 291 void *ret; 292 293 if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) 294 return 0; 295 296 /* 297 * Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's 298 * not safe to CoW the page containing the CPU exception vectors. 299 */ 300 ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE, 301 VM_READ | VM_EXEC | 302 VM_MAYREAD | VM_MAYEXEC, 303 &aarch32_vdso_maps[AA32_MAP_VECTORS]); 304 305 return PTR_ERR_OR_ZERO(ret); 306 } 307 308 #ifndef CONFIG_COMPAT_VDSO 309 static int aarch32_sigreturn_setup(struct mm_struct *mm) 310 { 311 unsigned long addr; 312 void *ret; 313 314 addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); 315 if (IS_ERR_VALUE(addr)) { 316 ret = ERR_PTR(addr); 317 goto out; 318 } 319 320 /* 321 * VM_MAYWRITE is required to allow gdb to Copy-on-Write and 322 * set breakpoints. 323 */ 324 ret = _install_special_mapping(mm, addr, PAGE_SIZE, 325 VM_READ | VM_EXEC | VM_MAYREAD | 326 VM_MAYWRITE | VM_MAYEXEC, 327 &aarch32_vdso_maps[AA32_MAP_SIGPAGE]); 328 if (IS_ERR(ret)) 329 goto out; 330 331 mm->context.vdso = (void *)addr; 332 333 out: 334 return PTR_ERR_OR_ZERO(ret); 335 } 336 #endif /* !CONFIG_COMPAT_VDSO */ 337 338 int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 339 { 340 struct mm_struct *mm = current->mm; 341 int ret; 342 343 if (mmap_write_lock_killable(mm)) 344 return -EINTR; 345 346 ret = aarch32_kuser_helpers_setup(mm); 347 if (ret) 348 goto out; 349 350 #ifdef CONFIG_COMPAT_VDSO 351 ret = __setup_additional_pages(VDSO_ABI_AA32, 352 mm, 353 bprm, 354 uses_interp); 355 #else 356 ret = aarch32_sigreturn_setup(mm); 357 #endif /* CONFIG_COMPAT_VDSO */ 358 359 out: 360 mmap_write_unlock(mm); 361 return ret; 362 } 363 #endif /* CONFIG_COMPAT */ 364 365 static int vdso_mremap(const struct vm_special_mapping *sm, 366 struct vm_area_struct *new_vma) 367 { 368 return __vdso_remap(VDSO_ABI_AA64, sm, new_vma); 369 } 370 371 enum aarch64_map { 372 AA64_MAP_VVAR, 373 AA64_MAP_VDSO, 374 }; 375 376 static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = { 377 [AA64_MAP_VVAR] = { 378 .name = "[vvar]", 379 }, 380 [AA64_MAP_VDSO] = { 381 .name = "[vdso]", 382 .mremap = vdso_mremap, 383 }, 384 }; 385 386 static int __init vdso_init(void) 387 { 388 vdso_info[VDSO_ABI_AA64].dm = &aarch64_vdso_maps[AA64_MAP_VVAR]; 389 vdso_info[VDSO_ABI_AA64].cm = &aarch64_vdso_maps[AA64_MAP_VDSO]; 390 391 return __vdso_init(VDSO_ABI_AA64); 392 } 393 arch_initcall(vdso_init); 394 395 int arch_setup_additional_pages(struct linux_binprm *bprm, 396 int uses_interp) 397 { 398 struct mm_struct *mm = current->mm; 399 int ret; 400 401 if (mmap_write_lock_killable(mm)) 402 return -EINTR; 403 404 ret = __setup_additional_pages(VDSO_ABI_AA64, 405 mm, 406 bprm, 407 uses_interp); 408 409 mmap_write_unlock(mm); 410 411 return ret; 412 } 413