1 // SPDX-License-Identifier: GPL-2.0-or-later 2 3 /* 4 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp. 5 * <benh@kernel.crashing.org> 6 */ 7 8 #include <linux/errno.h> 9 #include <linux/sched.h> 10 #include <linux/kernel.h> 11 #include <linux/mm.h> 12 #include <linux/smp.h> 13 #include <linux/stddef.h> 14 #include <linux/unistd.h> 15 #include <linux/slab.h> 16 #include <linux/user.h> 17 #include <linux/elf.h> 18 #include <linux/security.h> 19 #include <linux/memblock.h> 20 #include <linux/syscalls.h> 21 #include <linux/time_namespace.h> 22 #include <vdso/datapage.h> 23 24 #include <asm/syscall.h> 25 #include <asm/processor.h> 26 #include <asm/mmu.h> 27 #include <asm/mmu_context.h> 28 #include <asm/prom.h> 29 #include <asm/machdep.h> 30 #include <asm/cputable.h> 31 #include <asm/sections.h> 32 #include <asm/firmware.h> 33 #include <asm/vdso.h> 34 #include <asm/vdso_datapage.h> 35 #include <asm/setup.h> 36 37 /* The alignment of the vDSO */ 38 #define VDSO_ALIGNMENT (1 << 16) 39 40 extern char vdso32_start, vdso32_end; 41 extern char vdso64_start, vdso64_end; 42 43 /* 44 * The vdso data page (aka. systemcfg for old ppc64 fans) is here. 45 * Once the early boot kernel code no longer needs to muck around 46 * with it, it will become dynamically allocated 47 */ 48 static union { 49 struct vdso_arch_data data; 50 u8 page[PAGE_SIZE]; 51 } vdso_data_store __page_aligned_data; 52 struct vdso_arch_data *vdso_data = &vdso_data_store.data; 53 54 enum vvar_pages { 55 VVAR_DATA_PAGE_OFFSET, 56 VVAR_TIMENS_PAGE_OFFSET, 57 VVAR_NR_PAGES, 58 }; 59 60 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma, 61 unsigned long text_size) 62 { 63 unsigned long new_size = new_vma->vm_end - new_vma->vm_start; 64 65 if (new_size != text_size) 66 return -EINVAL; 67 68 current->mm->context.vdso = (void __user *)new_vma->vm_start; 69 70 return 0; 71 } 72 73 static int vdso32_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) 74 { 75 return vdso_mremap(sm, new_vma, &vdso32_end - &vdso32_start); 76 } 77 78 static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) 79 { 80 return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start); 81 } 82 83 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, 84 struct vm_area_struct *vma, struct vm_fault *vmf); 85 86 static struct vm_special_mapping vvar_spec __ro_after_init = { 87 .name = "[vvar]", 88 .fault = vvar_fault, 89 }; 90 91 static struct vm_special_mapping vdso32_spec __ro_after_init = { 92 .name = "[vdso]", 93 .mremap = vdso32_mremap, 94 }; 95 96 static struct vm_special_mapping vdso64_spec __ro_after_init = { 97 .name = "[vdso]", 98 .mremap = vdso64_mremap, 99 }; 100 101 #ifdef CONFIG_TIME_NS 102 struct vdso_data *arch_get_vdso_data(void *vvar_page) 103 { 104 return ((struct vdso_arch_data *)vvar_page)->data; 105 } 106 107 /* 108 * The vvar mapping contains data for a specific time namespace, so when a task 109 * changes namespace we must unmap its vvar data for the old namespace. 110 * Subsequent faults will map in data for the new namespace. 111 * 112 * For more details see timens_setup_vdso_data(). 113 */ 114 int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) 115 { 116 struct mm_struct *mm = task->mm; 117 struct vm_area_struct *vma; 118 119 mmap_read_lock(mm); 120 121 for (vma = mm->mmap; vma; vma = vma->vm_next) { 122 unsigned long size = vma->vm_end - vma->vm_start; 123 124 if (vma_is_special_mapping(vma, &vvar_spec)) 125 zap_page_range(vma, vma->vm_start, size); 126 } 127 128 mmap_read_unlock(mm); 129 return 0; 130 } 131 132 static struct page *find_timens_vvar_page(struct vm_area_struct *vma) 133 { 134 if (likely(vma->vm_mm == current->mm)) 135 return current->nsproxy->time_ns->vvar_page; 136 137 /* 138 * VM_PFNMAP | VM_IO protect .fault() handler from being called 139 * through interfaces like /proc/$pid/mem or 140 * process_vm_{readv,writev}() as long as there's no .access() 141 * in special_mapping_vmops. 142 * For more details check_vma_flags() and __access_remote_vm() 143 */ 144 WARN(1, "vvar_page accessed remotely"); 145 146 return NULL; 147 } 148 #else 149 static struct page *find_timens_vvar_page(struct vm_area_struct *vma) 150 { 151 return NULL; 152 } 153 #endif 154 155 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, 156 struct vm_area_struct *vma, struct vm_fault *vmf) 157 { 158 struct page *timens_page = find_timens_vvar_page(vma); 159 unsigned long pfn; 160 161 switch (vmf->pgoff) { 162 case VVAR_DATA_PAGE_OFFSET: 163 if (timens_page) 164 pfn = page_to_pfn(timens_page); 165 else 166 pfn = virt_to_pfn(vdso_data); 167 break; 168 #ifdef CONFIG_TIME_NS 169 case VVAR_TIMENS_PAGE_OFFSET: 170 /* 171 * If a task belongs to a time namespace then a namespace 172 * specific VVAR is mapped with the VVAR_DATA_PAGE_OFFSET and 173 * the real VVAR page is mapped with the VVAR_TIMENS_PAGE_OFFSET 174 * offset. 175 * See also the comment near timens_setup_vdso_data(). 176 */ 177 if (!timens_page) 178 return VM_FAULT_SIGBUS; 179 pfn = virt_to_pfn(vdso_data); 180 break; 181 #endif /* CONFIG_TIME_NS */ 182 default: 183 return VM_FAULT_SIGBUS; 184 } 185 186 return vmf_insert_pfn(vma, vmf->address, pfn); 187 } 188 189 /* 190 * This is called from binfmt_elf, we create the special vma for the 191 * vDSO and insert it into the mm struct tree 192 */ 193 static int __arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 194 { 195 unsigned long vdso_size, vdso_base, mappings_size; 196 struct vm_special_mapping *vdso_spec; 197 unsigned long vvar_size = VVAR_NR_PAGES * PAGE_SIZE; 198 struct mm_struct *mm = current->mm; 199 struct vm_area_struct *vma; 200 201 if (is_32bit_task()) { 202 vdso_spec = &vdso32_spec; 203 vdso_size = &vdso32_end - &vdso32_start; 204 vdso_base = VDSO32_MBASE; 205 } else { 206 vdso_spec = &vdso64_spec; 207 vdso_size = &vdso64_end - &vdso64_start; 208 /* 209 * On 64bit we don't have a preferred map address. This 210 * allows get_unmapped_area to find an area near other mmaps 211 * and most likely share a SLB entry. 212 */ 213 vdso_base = 0; 214 } 215 216 mappings_size = vdso_size + vvar_size; 217 mappings_size += (VDSO_ALIGNMENT - 1) & PAGE_MASK; 218 219 /* 220 * pick a base address for the vDSO in process space. We try to put it 221 * at vdso_base which is the "natural" base for it, but we might fail 222 * and end up putting it elsewhere. 223 * Add enough to the size so that the result can be aligned. 224 */ 225 vdso_base = get_unmapped_area(NULL, vdso_base, mappings_size, 0, 0); 226 if (IS_ERR_VALUE(vdso_base)) 227 return vdso_base; 228 229 /* Add required alignment. */ 230 vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT); 231 232 /* 233 * Put vDSO base into mm struct. We need to do this before calling 234 * install_special_mapping or the perf counter mmap tracking code 235 * will fail to recognise it as a vDSO. 236 */ 237 mm->context.vdso = (void __user *)vdso_base + vvar_size; 238 239 vma = _install_special_mapping(mm, vdso_base, vvar_size, 240 VM_READ | VM_MAYREAD | VM_IO | 241 VM_DONTDUMP | VM_PFNMAP, &vvar_spec); 242 if (IS_ERR(vma)) 243 return PTR_ERR(vma); 244 245 /* 246 * our vma flags don't have VM_WRITE so by default, the process isn't 247 * allowed to write those pages. 248 * gdb can break that with ptrace interface, and thus trigger COW on 249 * those pages but it's then your responsibility to never do that on 250 * the "data" page of the vDSO or you'll stop getting kernel updates 251 * and your nice userland gettimeofday will be totally dead. 252 * It's fine to use that for setting breakpoints in the vDSO code 253 * pages though. 254 */ 255 vma = _install_special_mapping(mm, vdso_base + vvar_size, vdso_size, 256 VM_READ | VM_EXEC | VM_MAYREAD | 257 VM_MAYWRITE | VM_MAYEXEC, vdso_spec); 258 if (IS_ERR(vma)) 259 do_munmap(mm, vdso_base, vvar_size, NULL); 260 261 return PTR_ERR_OR_ZERO(vma); 262 } 263 264 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 265 { 266 struct mm_struct *mm = current->mm; 267 int rc; 268 269 mm->context.vdso = NULL; 270 271 if (mmap_write_lock_killable(mm)) 272 return -EINTR; 273 274 rc = __arch_setup_additional_pages(bprm, uses_interp); 275 if (rc) 276 mm->context.vdso = NULL; 277 278 mmap_write_unlock(mm); 279 return rc; 280 } 281 282 #define VDSO_DO_FIXUPS(type, value, bits, sec) do { \ 283 void *__start = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_start); \ 284 void *__end = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_end); \ 285 \ 286 do_##type##_fixups((value), __start, __end); \ 287 } while (0) 288 289 static void __init vdso_fixup_features(void) 290 { 291 #ifdef CONFIG_PPC64 292 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 64, ftr_fixup); 293 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 64, mmu_ftr_fixup); 294 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 64, fw_ftr_fixup); 295 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 64, lwsync_fixup); 296 #endif /* CONFIG_PPC64 */ 297 298 #ifdef CONFIG_VDSO32 299 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 32, ftr_fixup); 300 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 32, mmu_ftr_fixup); 301 #ifdef CONFIG_PPC64 302 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 32, fw_ftr_fixup); 303 #endif /* CONFIG_PPC64 */ 304 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 32, lwsync_fixup); 305 #endif 306 } 307 308 /* 309 * Called from setup_arch to initialize the bitmap of available 310 * syscalls in the systemcfg page 311 */ 312 static void __init vdso_setup_syscall_map(void) 313 { 314 unsigned int i; 315 316 for (i = 0; i < NR_syscalls; i++) { 317 if (sys_call_table[i] != (unsigned long)&sys_ni_syscall) 318 vdso_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); 319 if (IS_ENABLED(CONFIG_COMPAT) && 320 compat_sys_call_table[i] != (unsigned long)&sys_ni_syscall) 321 vdso_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); 322 } 323 } 324 325 #ifdef CONFIG_PPC64 326 int vdso_getcpu_init(void) 327 { 328 unsigned long cpu, node, val; 329 330 /* 331 * SPRG_VDSO contains the CPU in the bottom 16 bits and the NUMA node 332 * in the next 16 bits. The VDSO uses this to implement getcpu(). 333 */ 334 cpu = get_cpu(); 335 WARN_ON_ONCE(cpu > 0xffff); 336 337 node = cpu_to_node(cpu); 338 WARN_ON_ONCE(node > 0xffff); 339 340 val = (cpu & 0xffff) | ((node & 0xffff) << 16); 341 mtspr(SPRN_SPRG_VDSO_WRITE, val); 342 get_paca()->sprg_vdso = val; 343 344 put_cpu(); 345 346 return 0; 347 } 348 /* We need to call this before SMP init */ 349 early_initcall(vdso_getcpu_init); 350 #endif 351 352 static struct page ** __init vdso_setup_pages(void *start, void *end) 353 { 354 int i; 355 struct page **pagelist; 356 int pages = (end - start) >> PAGE_SHIFT; 357 358 pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL); 359 if (!pagelist) 360 panic("%s: Cannot allocate page list for VDSO", __func__); 361 362 for (i = 0; i < pages; i++) 363 pagelist[i] = virt_to_page(start + i * PAGE_SIZE); 364 365 return pagelist; 366 } 367 368 static int __init vdso_init(void) 369 { 370 #ifdef CONFIG_PPC64 371 /* 372 * Fill up the "systemcfg" stuff for backward compatibility 373 */ 374 strcpy((char *)vdso_data->eye_catcher, "SYSTEMCFG:PPC64"); 375 vdso_data->version.major = SYSTEMCFG_MAJOR; 376 vdso_data->version.minor = SYSTEMCFG_MINOR; 377 vdso_data->processor = mfspr(SPRN_PVR); 378 /* 379 * Fake the old platform number for pSeries and add 380 * in LPAR bit if necessary 381 */ 382 vdso_data->platform = 0x100; 383 if (firmware_has_feature(FW_FEATURE_LPAR)) 384 vdso_data->platform |= 1; 385 vdso_data->physicalMemorySize = memblock_phys_mem_size(); 386 vdso_data->dcache_size = ppc64_caches.l1d.size; 387 vdso_data->dcache_line_size = ppc64_caches.l1d.line_size; 388 vdso_data->icache_size = ppc64_caches.l1i.size; 389 vdso_data->icache_line_size = ppc64_caches.l1i.line_size; 390 vdso_data->dcache_block_size = ppc64_caches.l1d.block_size; 391 vdso_data->icache_block_size = ppc64_caches.l1i.block_size; 392 vdso_data->dcache_log_block_size = ppc64_caches.l1d.log_block_size; 393 vdso_data->icache_log_block_size = ppc64_caches.l1i.log_block_size; 394 #endif /* CONFIG_PPC64 */ 395 396 vdso_setup_syscall_map(); 397 398 vdso_fixup_features(); 399 400 if (IS_ENABLED(CONFIG_VDSO32)) 401 vdso32_spec.pages = vdso_setup_pages(&vdso32_start, &vdso32_end); 402 403 if (IS_ENABLED(CONFIG_PPC64)) 404 vdso64_spec.pages = vdso_setup_pages(&vdso64_start, &vdso64_end); 405 406 smp_wmb(); 407 408 return 0; 409 } 410 arch_initcall(vdso_init); 411