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/syscalls.h> 20 #include <linux/vdso_datastore.h> 21 #include <vdso/datapage.h> 22 23 #include <asm/syscall.h> 24 #include <asm/processor.h> 25 #include <asm/mmu.h> 26 #include <asm/mmu_context.h> 27 #include <asm/machdep.h> 28 #include <asm/cputable.h> 29 #include <asm/sections.h> 30 #include <asm/firmware.h> 31 #include <asm/vdso.h> 32 #include <asm/vdso_datapage.h> 33 #include <asm/setup.h> 34 35 static_assert(__VDSO_PAGES == VDSO_NR_PAGES); 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 long sys_ni_syscall(void); 44 45 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma, 46 unsigned long text_size) 47 { 48 unsigned long new_size = new_vma->vm_end - new_vma->vm_start; 49 50 if (new_size != text_size) 51 return -EINVAL; 52 53 current->mm->context.vdso = (void __user *)new_vma->vm_start; 54 55 return 0; 56 } 57 58 static int vdso32_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) 59 { 60 return vdso_mremap(sm, new_vma, &vdso32_end - &vdso32_start); 61 } 62 63 static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) 64 { 65 return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start); 66 } 67 68 static void vdso_close(const struct vm_special_mapping *sm, struct vm_area_struct *vma) 69 { 70 struct mm_struct *mm = vma->vm_mm; 71 72 /* 73 * close() is called for munmap() but also for mremap(). In the mremap() 74 * case the vdso pointer has already been updated by the mremap() hook 75 * above, so it must not be set to NULL here. 76 */ 77 if (vma->vm_start != (unsigned long)mm->context.vdso) 78 return; 79 80 mm->context.vdso = NULL; 81 } 82 83 static struct vm_special_mapping vdso32_spec __ro_after_init = { 84 .name = "[vdso]", 85 .mremap = vdso32_mremap, 86 .close = vdso_close, 87 }; 88 89 static struct vm_special_mapping vdso64_spec __ro_after_init = { 90 .name = "[vdso]", 91 .mremap = vdso64_mremap, 92 .close = vdso_close, 93 }; 94 95 /* 96 * This is called from binfmt_elf, we create the special vma for the 97 * vDSO and insert it into the mm struct tree 98 */ 99 static int __arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 100 { 101 unsigned long vdso_size, vdso_base, mappings_size; 102 struct vm_special_mapping *vdso_spec; 103 unsigned long vvar_size = VDSO_NR_PAGES * PAGE_SIZE; 104 struct mm_struct *mm = current->mm; 105 struct vm_area_struct *vma; 106 107 if (is_32bit_task()) { 108 vdso_spec = &vdso32_spec; 109 vdso_size = &vdso32_end - &vdso32_start; 110 } else { 111 vdso_spec = &vdso64_spec; 112 vdso_size = &vdso64_end - &vdso64_start; 113 } 114 115 mappings_size = vdso_size + vvar_size; 116 mappings_size += (VDSO_ALIGNMENT - 1) & PAGE_MASK; 117 118 /* 119 * Pick a base address for the vDSO in process space. 120 * Add enough to the size so that the result can be aligned. 121 */ 122 vdso_base = get_unmapped_area(NULL, 0, mappings_size, 0, 0); 123 if (IS_ERR_VALUE(vdso_base)) 124 return vdso_base; 125 126 /* Add required alignment. */ 127 vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT); 128 129 vma = vdso_install_vvar_mapping(mm, vdso_base); 130 if (IS_ERR(vma)) 131 return PTR_ERR(vma); 132 133 /* 134 * our vma flags don't have VM_WRITE so by default, the process isn't 135 * allowed to write those pages. 136 * gdb can break that with ptrace interface, and thus trigger COW on 137 * those pages but it's then your responsibility to never do that on 138 * the "data" page of the vDSO or you'll stop getting kernel updates 139 * and your nice userland gettimeofday will be totally dead. 140 * It's fine to use that for setting breakpoints in the vDSO code 141 * pages though. 142 */ 143 vma = _install_special_mapping(mm, vdso_base + vvar_size, vdso_size, 144 VM_READ | VM_EXEC | VM_MAYREAD | 145 VM_MAYWRITE | VM_MAYEXEC, vdso_spec); 146 if (IS_ERR(vma)) { 147 do_munmap(mm, vdso_base, vvar_size, NULL); 148 return PTR_ERR(vma); 149 } 150 151 // Now that the mappings are in place, set the mm VDSO pointer 152 mm->context.vdso = (void __user *)vdso_base + vvar_size; 153 154 return 0; 155 } 156 157 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 158 { 159 struct mm_struct *mm = current->mm; 160 int rc; 161 162 mm->context.vdso = NULL; 163 164 if (mmap_write_lock_killable(mm)) 165 return -EINTR; 166 167 rc = __arch_setup_additional_pages(bprm, uses_interp); 168 169 mmap_write_unlock(mm); 170 return rc; 171 } 172 173 #define VDSO_DO_FIXUPS(type, value, bits, sec) do { \ 174 void *__start = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_start); \ 175 void *__end = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_end); \ 176 \ 177 do_##type##_fixups((value), __start, __end); \ 178 } while (0) 179 180 static void __init vdso_fixup_features(void) 181 { 182 #ifdef CONFIG_PPC64 183 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 64, ftr_fixup); 184 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 64, mmu_ftr_fixup); 185 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 64, fw_ftr_fixup); 186 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 64, lwsync_fixup); 187 #endif /* CONFIG_PPC64 */ 188 189 #ifdef CONFIG_VDSO32 190 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 32, ftr_fixup); 191 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 32, mmu_ftr_fixup); 192 #ifdef CONFIG_PPC64 193 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 32, fw_ftr_fixup); 194 #endif /* CONFIG_PPC64 */ 195 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 32, lwsync_fixup); 196 #endif 197 } 198 199 /* 200 * Called from setup_arch to initialize the bitmap of available 201 * syscalls in the systemcfg page 202 */ 203 static void __init vdso_setup_syscall_map(void) 204 { 205 unsigned int i; 206 207 for (i = 0; i < NR_syscalls; i++) { 208 if (sys_call_table[i] != (void *)&sys_ni_syscall) 209 vdso_k_arch_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); 210 if (IS_ENABLED(CONFIG_COMPAT) && 211 compat_sys_call_table[i] != (void *)&sys_ni_syscall) 212 vdso_k_arch_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); 213 } 214 } 215 216 #ifdef CONFIG_PPC64 217 int vdso_getcpu_init(void) 218 { 219 unsigned long cpu, node, val; 220 221 /* 222 * SPRG_VDSO contains the CPU in the bottom 16 bits and the NUMA node 223 * in the next 16 bits. The VDSO uses this to implement getcpu(). 224 */ 225 cpu = get_cpu(); 226 WARN_ON_ONCE(cpu > 0xffff); 227 228 node = cpu_to_node(cpu); 229 WARN_ON_ONCE(node > 0xffff); 230 231 val = (cpu & 0xffff) | ((node & 0xffff) << 16); 232 mtspr(SPRN_SPRG_VDSO_WRITE, val); 233 get_paca()->sprg_vdso = val; 234 235 put_cpu(); 236 237 return 0; 238 } 239 /* We need to call this before SMP init */ 240 early_initcall(vdso_getcpu_init); 241 #endif 242 243 static struct page ** __init vdso_setup_pages(void *start, void *end) 244 { 245 int i; 246 struct page **pagelist; 247 int pages = (end - start) >> PAGE_SHIFT; 248 249 pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL); 250 if (!pagelist) 251 panic("%s: Cannot allocate page list for VDSO", __func__); 252 253 for (i = 0; i < pages; i++) 254 pagelist[i] = virt_to_page(start + i * PAGE_SIZE); 255 256 return pagelist; 257 } 258 259 static int __init vdso_init(void) 260 { 261 #ifdef CONFIG_PPC64 262 vdso_k_arch_data->dcache_block_size = ppc64_caches.l1d.block_size; 263 vdso_k_arch_data->icache_block_size = ppc64_caches.l1i.block_size; 264 vdso_k_arch_data->dcache_log_block_size = ppc64_caches.l1d.log_block_size; 265 vdso_k_arch_data->icache_log_block_size = ppc64_caches.l1i.log_block_size; 266 #endif /* CONFIG_PPC64 */ 267 268 vdso_setup_syscall_map(); 269 270 vdso_fixup_features(); 271 272 if (IS_ENABLED(CONFIG_VDSO32)) 273 vdso32_spec.pages = vdso_setup_pages(&vdso32_start, &vdso32_end); 274 275 if (IS_ENABLED(CONFIG_PPC64)) 276 vdso64_spec.pages = vdso_setup_pages(&vdso64_start, &vdso64_end); 277 278 smp_wmb(); 279 280 return 0; 281 } 282 arch_initcall(vdso_init); 283