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 <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/prom.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 39 extern char vdso32_start, vdso32_end; 40 extern char vdso64_start, vdso64_end; 41 42 /* 43 * The vdso data page (aka. systemcfg for old ppc64 fans) is here. 44 * Once the early boot kernel code no longer needs to muck around 45 * with it, it will become dynamically allocated 46 */ 47 static union { 48 struct vdso_arch_data data; 49 u8 page[PAGE_SIZE]; 50 } vdso_data_store __page_aligned_data; 51 struct vdso_arch_data *vdso_data = &vdso_data_store.data; 52 53 static int vdso_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma, 54 unsigned long text_size) 55 { 56 unsigned long new_size = new_vma->vm_end - new_vma->vm_start; 57 58 if (new_size != text_size + PAGE_SIZE) 59 return -EINVAL; 60 61 current->mm->context.vdso = (void __user *)new_vma->vm_start + PAGE_SIZE; 62 63 return 0; 64 } 65 66 static int vdso32_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) 67 { 68 return vdso_mremap(sm, new_vma, &vdso32_end - &vdso32_start); 69 } 70 71 static int vdso64_mremap(const struct vm_special_mapping *sm, struct vm_area_struct *new_vma) 72 { 73 return vdso_mremap(sm, new_vma, &vdso64_end - &vdso64_start); 74 } 75 76 static struct vm_special_mapping vdso32_spec __ro_after_init = { 77 .name = "[vdso]", 78 .mremap = vdso32_mremap, 79 }; 80 81 static struct vm_special_mapping vdso64_spec __ro_after_init = { 82 .name = "[vdso]", 83 .mremap = vdso64_mremap, 84 }; 85 86 /* 87 * This is called from binfmt_elf, we create the special vma for the 88 * vDSO and insert it into the mm struct tree 89 */ 90 static int __arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 91 { 92 struct mm_struct *mm = current->mm; 93 struct vm_special_mapping *vdso_spec; 94 struct vm_area_struct *vma; 95 unsigned long vdso_size; 96 unsigned long vdso_base; 97 98 if (is_32bit_task()) { 99 vdso_spec = &vdso32_spec; 100 vdso_size = &vdso32_end - &vdso32_start; 101 vdso_base = VDSO32_MBASE; 102 } else { 103 vdso_spec = &vdso64_spec; 104 vdso_size = &vdso64_end - &vdso64_start; 105 /* 106 * On 64bit we don't have a preferred map address. This 107 * allows get_unmapped_area to find an area near other mmaps 108 * and most likely share a SLB entry. 109 */ 110 vdso_base = 0; 111 } 112 113 /* Add a page to the vdso size for the data page */ 114 vdso_size += PAGE_SIZE; 115 116 /* 117 * pick a base address for the vDSO in process space. We try to put it 118 * at vdso_base which is the "natural" base for it, but we might fail 119 * and end up putting it elsewhere. 120 * Add enough to the size so that the result can be aligned. 121 */ 122 vdso_base = get_unmapped_area(NULL, vdso_base, 123 vdso_size + ((VDSO_ALIGNMENT - 1) & PAGE_MASK), 124 0, 0); 125 if (IS_ERR_VALUE(vdso_base)) 126 return vdso_base; 127 128 /* Add required alignment. */ 129 vdso_base = ALIGN(vdso_base, VDSO_ALIGNMENT); 130 131 /* 132 * Put vDSO base into mm struct. We need to do this before calling 133 * install_special_mapping or the perf counter mmap tracking code 134 * will fail to recognise it as a vDSO. 135 */ 136 mm->context.vdso = (void __user *)vdso_base + PAGE_SIZE; 137 138 /* 139 * our vma flags don't have VM_WRITE so by default, the process isn't 140 * allowed to write those pages. 141 * gdb can break that with ptrace interface, and thus trigger COW on 142 * those pages but it's then your responsibility to never do that on 143 * the "data" page of the vDSO or you'll stop getting kernel updates 144 * and your nice userland gettimeofday will be totally dead. 145 * It's fine to use that for setting breakpoints in the vDSO code 146 * pages though. 147 */ 148 vma = _install_special_mapping(mm, vdso_base, vdso_size, 149 VM_READ | VM_EXEC | VM_MAYREAD | 150 VM_MAYWRITE | VM_MAYEXEC, vdso_spec); 151 return PTR_ERR_OR_ZERO(vma); 152 } 153 154 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 155 { 156 struct mm_struct *mm = current->mm; 157 int rc; 158 159 mm->context.vdso = NULL; 160 161 if (mmap_write_lock_killable(mm)) 162 return -EINTR; 163 164 rc = __arch_setup_additional_pages(bprm, uses_interp); 165 if (rc) 166 mm->context.vdso = NULL; 167 168 mmap_write_unlock(mm); 169 return rc; 170 } 171 172 #define VDSO_DO_FIXUPS(type, value, bits, sec) do { \ 173 void *__start = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_start); \ 174 void *__end = (void *)VDSO##bits##_SYMBOL(&vdso##bits##_start, sec##_end); \ 175 \ 176 do_##type##_fixups((value), __start, __end); \ 177 } while (0) 178 179 static void __init vdso_fixup_features(void) 180 { 181 #ifdef CONFIG_PPC64 182 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 64, ftr_fixup); 183 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 64, mmu_ftr_fixup); 184 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 64, fw_ftr_fixup); 185 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 64, lwsync_fixup); 186 #endif /* CONFIG_PPC64 */ 187 188 #ifdef CONFIG_VDSO32 189 VDSO_DO_FIXUPS(feature, cur_cpu_spec->cpu_features, 32, ftr_fixup); 190 VDSO_DO_FIXUPS(feature, cur_cpu_spec->mmu_features, 32, mmu_ftr_fixup); 191 #ifdef CONFIG_PPC64 192 VDSO_DO_FIXUPS(feature, powerpc_firmware_features, 32, fw_ftr_fixup); 193 #endif /* CONFIG_PPC64 */ 194 VDSO_DO_FIXUPS(lwsync, cur_cpu_spec->cpu_features, 32, lwsync_fixup); 195 #endif 196 } 197 198 /* 199 * Called from setup_arch to initialize the bitmap of available 200 * syscalls in the systemcfg page 201 */ 202 static void __init vdso_setup_syscall_map(void) 203 { 204 unsigned int i; 205 206 for (i = 0; i < NR_syscalls; i++) { 207 if (sys_call_table[i] != (unsigned long)&sys_ni_syscall) 208 vdso_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); 209 if (IS_ENABLED(CONFIG_COMPAT) && 210 compat_sys_call_table[i] != (unsigned long)&sys_ni_syscall) 211 vdso_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); 212 } 213 } 214 215 #ifdef CONFIG_PPC64 216 int vdso_getcpu_init(void) 217 { 218 unsigned long cpu, node, val; 219 220 /* 221 * SPRG_VDSO contains the CPU in the bottom 16 bits and the NUMA node 222 * in the next 16 bits. The VDSO uses this to implement getcpu(). 223 */ 224 cpu = get_cpu(); 225 WARN_ON_ONCE(cpu > 0xffff); 226 227 node = cpu_to_node(cpu); 228 WARN_ON_ONCE(node > 0xffff); 229 230 val = (cpu & 0xffff) | ((node & 0xffff) << 16); 231 mtspr(SPRN_SPRG_VDSO_WRITE, val); 232 get_paca()->sprg_vdso = val; 233 234 put_cpu(); 235 236 return 0; 237 } 238 /* We need to call this before SMP init */ 239 early_initcall(vdso_getcpu_init); 240 #endif 241 242 static struct page ** __init vdso_setup_pages(void *start, void *end) 243 { 244 int i; 245 struct page **pagelist; 246 int pages = (end - start) >> PAGE_SHIFT; 247 248 pagelist = kcalloc(pages + 1, sizeof(struct page *), GFP_KERNEL); 249 if (!pagelist) 250 panic("%s: Cannot allocate page list for VDSO", __func__); 251 252 pagelist[0] = virt_to_page(vdso_data); 253 254 for (i = 0; i < pages; i++) 255 pagelist[i + 1] = virt_to_page(start + i * PAGE_SIZE); 256 257 return pagelist; 258 } 259 260 static int __init vdso_init(void) 261 { 262 #ifdef CONFIG_PPC64 263 /* 264 * Fill up the "systemcfg" stuff for backward compatibility 265 */ 266 strcpy((char *)vdso_data->eye_catcher, "SYSTEMCFG:PPC64"); 267 vdso_data->version.major = SYSTEMCFG_MAJOR; 268 vdso_data->version.minor = SYSTEMCFG_MINOR; 269 vdso_data->processor = mfspr(SPRN_PVR); 270 /* 271 * Fake the old platform number for pSeries and add 272 * in LPAR bit if necessary 273 */ 274 vdso_data->platform = 0x100; 275 if (firmware_has_feature(FW_FEATURE_LPAR)) 276 vdso_data->platform |= 1; 277 vdso_data->physicalMemorySize = memblock_phys_mem_size(); 278 vdso_data->dcache_size = ppc64_caches.l1d.size; 279 vdso_data->dcache_line_size = ppc64_caches.l1d.line_size; 280 vdso_data->icache_size = ppc64_caches.l1i.size; 281 vdso_data->icache_line_size = ppc64_caches.l1i.line_size; 282 vdso_data->dcache_block_size = ppc64_caches.l1d.block_size; 283 vdso_data->icache_block_size = ppc64_caches.l1i.block_size; 284 vdso_data->dcache_log_block_size = ppc64_caches.l1d.log_block_size; 285 vdso_data->icache_log_block_size = ppc64_caches.l1i.log_block_size; 286 #endif /* CONFIG_PPC64 */ 287 288 vdso_setup_syscall_map(); 289 290 vdso_fixup_features(); 291 292 if (IS_ENABLED(CONFIG_VDSO32)) 293 vdso32_spec.pages = vdso_setup_pages(&vdso32_start, &vdso32_end); 294 295 if (IS_ENABLED(CONFIG_PPC64)) 296 vdso64_spec.pages = vdso_setup_pages(&vdso64_start, &vdso64_end); 297 298 smp_wmb(); 299 300 return 0; 301 } 302 arch_initcall(vdso_init); 303