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