1 /* 2 * vdso setup for s390 3 * 4 * Copyright IBM Corp. 2008 5 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com) 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License (version 2 only) 9 * as published by the Free Software Foundation. 10 */ 11 12 #include <linux/module.h> 13 #include <linux/errno.h> 14 #include <linux/sched.h> 15 #include <linux/kernel.h> 16 #include <linux/mm.h> 17 #include <linux/smp.h> 18 #include <linux/stddef.h> 19 #include <linux/unistd.h> 20 #include <linux/slab.h> 21 #include <linux/user.h> 22 #include <linux/elf.h> 23 #include <linux/security.h> 24 #include <linux/bootmem.h> 25 #include <linux/compat.h> 26 #include <asm/asm-offsets.h> 27 #include <asm/pgtable.h> 28 #include <asm/system.h> 29 #include <asm/processor.h> 30 #include <asm/mmu.h> 31 #include <asm/mmu_context.h> 32 #include <asm/sections.h> 33 #include <asm/vdso.h> 34 35 #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT) 36 extern char vdso32_start, vdso32_end; 37 static void *vdso32_kbase = &vdso32_start; 38 static unsigned int vdso32_pages; 39 static struct page **vdso32_pagelist; 40 #endif 41 42 #ifdef CONFIG_64BIT 43 extern char vdso64_start, vdso64_end; 44 static void *vdso64_kbase = &vdso64_start; 45 static unsigned int vdso64_pages; 46 static struct page **vdso64_pagelist; 47 #endif /* CONFIG_64BIT */ 48 49 /* 50 * Should the kernel map a VDSO page into processes and pass its 51 * address down to glibc upon exec()? 52 */ 53 unsigned int __read_mostly vdso_enabled = 1; 54 55 static int __init vdso_setup(char *s) 56 { 57 unsigned long val; 58 int rc; 59 60 rc = 0; 61 if (strncmp(s, "on", 3) == 0) 62 vdso_enabled = 1; 63 else if (strncmp(s, "off", 4) == 0) 64 vdso_enabled = 0; 65 else { 66 rc = strict_strtoul(s, 0, &val); 67 vdso_enabled = rc ? 0 : !!val; 68 } 69 return !rc; 70 } 71 __setup("vdso=", vdso_setup); 72 73 /* 74 * The vdso data page 75 */ 76 static union { 77 struct vdso_data data; 78 u8 page[PAGE_SIZE]; 79 } vdso_data_store __page_aligned_data; 80 struct vdso_data *vdso_data = &vdso_data_store.data; 81 82 /* 83 * Setup vdso data page. 84 */ 85 static void vdso_init_data(struct vdso_data *vd) 86 { 87 unsigned int facility_list; 88 89 facility_list = stfl(); 90 vd->ectg_available = 91 user_mode != HOME_SPACE_MODE && (facility_list & 1); 92 } 93 94 #ifdef CONFIG_64BIT 95 /* 96 * Setup per cpu vdso data page. 97 */ 98 static void vdso_init_per_cpu_data(int cpu, struct vdso_per_cpu_data *vpcd) 99 { 100 } 101 102 /* 103 * Allocate/free per cpu vdso data. 104 */ 105 #ifdef CONFIG_64BIT 106 #define SEGMENT_ORDER 2 107 #else 108 #define SEGMENT_ORDER 1 109 #endif 110 111 int vdso_alloc_per_cpu(int cpu, struct _lowcore *lowcore) 112 { 113 unsigned long segment_table, page_table, page_frame; 114 u32 *psal, *aste; 115 int i; 116 117 lowcore->vdso_per_cpu_data = __LC_PASTE; 118 119 if (user_mode == HOME_SPACE_MODE || !vdso_enabled) 120 return 0; 121 122 segment_table = __get_free_pages(GFP_KERNEL, SEGMENT_ORDER); 123 page_table = get_zeroed_page(GFP_KERNEL | GFP_DMA); 124 page_frame = get_zeroed_page(GFP_KERNEL); 125 if (!segment_table || !page_table || !page_frame) 126 goto out; 127 128 clear_table((unsigned long *) segment_table, _SEGMENT_ENTRY_EMPTY, 129 PAGE_SIZE << SEGMENT_ORDER); 130 clear_table((unsigned long *) page_table, _PAGE_TYPE_EMPTY, 131 256*sizeof(unsigned long)); 132 133 *(unsigned long *) segment_table = _SEGMENT_ENTRY + page_table; 134 *(unsigned long *) page_table = _PAGE_RO + page_frame; 135 136 psal = (u32 *) (page_table + 256*sizeof(unsigned long)); 137 aste = psal + 32; 138 139 for (i = 4; i < 32; i += 4) 140 psal[i] = 0x80000000; 141 142 lowcore->paste[4] = (u32)(addr_t) psal; 143 psal[0] = 0x20000000; 144 psal[2] = (u32)(addr_t) aste; 145 *(unsigned long *) (aste + 2) = segment_table + 146 _ASCE_TABLE_LENGTH + _ASCE_USER_BITS + _ASCE_TYPE_SEGMENT; 147 aste[4] = (u32)(addr_t) psal; 148 lowcore->vdso_per_cpu_data = page_frame; 149 150 vdso_init_per_cpu_data(cpu, (struct vdso_per_cpu_data *) page_frame); 151 return 0; 152 153 out: 154 free_page(page_frame); 155 free_page(page_table); 156 free_pages(segment_table, SEGMENT_ORDER); 157 return -ENOMEM; 158 } 159 160 void vdso_free_per_cpu(int cpu, struct _lowcore *lowcore) 161 { 162 unsigned long segment_table, page_table, page_frame; 163 u32 *psal, *aste; 164 165 if (user_mode == HOME_SPACE_MODE || !vdso_enabled) 166 return; 167 168 psal = (u32 *)(addr_t) lowcore->paste[4]; 169 aste = (u32 *)(addr_t) psal[2]; 170 segment_table = *(unsigned long *)(aste + 2) & PAGE_MASK; 171 page_table = *(unsigned long *) segment_table; 172 page_frame = *(unsigned long *) page_table; 173 174 free_page(page_frame); 175 free_page(page_table); 176 free_pages(segment_table, SEGMENT_ORDER); 177 } 178 179 static void __vdso_init_cr5(void *dummy) 180 { 181 unsigned long cr5; 182 183 cr5 = offsetof(struct _lowcore, paste); 184 __ctl_load(cr5, 5, 5); 185 } 186 187 static void vdso_init_cr5(void) 188 { 189 if (user_mode != HOME_SPACE_MODE && vdso_enabled) 190 on_each_cpu(__vdso_init_cr5, NULL, 1); 191 } 192 #endif /* CONFIG_64BIT */ 193 194 /* 195 * This is called from binfmt_elf, we create the special vma for the 196 * vDSO and insert it into the mm struct tree 197 */ 198 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 199 { 200 struct mm_struct *mm = current->mm; 201 struct page **vdso_pagelist; 202 unsigned long vdso_pages; 203 unsigned long vdso_base; 204 int rc; 205 206 if (!vdso_enabled) 207 return 0; 208 /* 209 * Only map the vdso for dynamically linked elf binaries. 210 */ 211 if (!uses_interp) 212 return 0; 213 214 vdso_base = mm->mmap_base; 215 #ifdef CONFIG_64BIT 216 vdso_pagelist = vdso64_pagelist; 217 vdso_pages = vdso64_pages; 218 #ifdef CONFIG_COMPAT 219 if (is_compat_task()) { 220 vdso_pagelist = vdso32_pagelist; 221 vdso_pages = vdso32_pages; 222 } 223 #endif 224 #else 225 vdso_pagelist = vdso32_pagelist; 226 vdso_pages = vdso32_pages; 227 #endif 228 229 /* 230 * vDSO has a problem and was disabled, just don't "enable" it for 231 * the process 232 */ 233 if (vdso_pages == 0) 234 return 0; 235 236 current->mm->context.vdso_base = 0; 237 238 /* 239 * pick a base address for the vDSO in process space. We try to put 240 * it at vdso_base which is the "natural" base for it, but we might 241 * fail and end up putting it elsewhere. 242 */ 243 down_write(&mm->mmap_sem); 244 vdso_base = get_unmapped_area(NULL, vdso_base, 245 vdso_pages << PAGE_SHIFT, 0, 0); 246 if (IS_ERR_VALUE(vdso_base)) { 247 rc = vdso_base; 248 goto out_up; 249 } 250 251 /* 252 * Put vDSO base into mm struct. We need to do this before calling 253 * install_special_mapping or the perf counter mmap tracking code 254 * will fail to recognise it as a vDSO (since arch_vma_name fails). 255 */ 256 current->mm->context.vdso_base = vdso_base; 257 258 /* 259 * our vma flags don't have VM_WRITE so by default, the process 260 * isn't allowed to write those pages. 261 * gdb can break that with ptrace interface, and thus trigger COW 262 * on those pages but it's then your responsibility to never do that 263 * on the "data" page of the vDSO or you'll stop getting kernel 264 * updates and your nice userland gettimeofday will be totally dead. 265 * It's fine to use that for setting breakpoints in the vDSO code 266 * pages though 267 * 268 * Make sure the vDSO gets into every core dump. 269 * Dumping its contents makes post-mortem fully interpretable later 270 * without matching up the same kernel and hardware config to see 271 * what PC values meant. 272 */ 273 rc = install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT, 274 VM_READ|VM_EXEC| 275 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| 276 VM_ALWAYSDUMP, 277 vdso_pagelist); 278 if (rc) 279 current->mm->context.vdso_base = 0; 280 out_up: 281 up_write(&mm->mmap_sem); 282 return rc; 283 } 284 285 const char *arch_vma_name(struct vm_area_struct *vma) 286 { 287 if (vma->vm_mm && vma->vm_start == vma->vm_mm->context.vdso_base) 288 return "[vdso]"; 289 return NULL; 290 } 291 292 static int __init vdso_init(void) 293 { 294 int i; 295 296 if (!vdso_enabled) 297 return 0; 298 vdso_init_data(vdso_data); 299 #if defined(CONFIG_32BIT) || defined(CONFIG_COMPAT) 300 /* Calculate the size of the 32 bit vDSO */ 301 vdso32_pages = ((&vdso32_end - &vdso32_start 302 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1; 303 304 /* Make sure pages are in the correct state */ 305 vdso32_pagelist = kzalloc(sizeof(struct page *) * (vdso32_pages + 1), 306 GFP_KERNEL); 307 BUG_ON(vdso32_pagelist == NULL); 308 for (i = 0; i < vdso32_pages - 1; i++) { 309 struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE); 310 ClearPageReserved(pg); 311 get_page(pg); 312 vdso32_pagelist[i] = pg; 313 } 314 vdso32_pagelist[vdso32_pages - 1] = virt_to_page(vdso_data); 315 vdso32_pagelist[vdso32_pages] = NULL; 316 #endif 317 318 #ifdef CONFIG_64BIT 319 /* Calculate the size of the 64 bit vDSO */ 320 vdso64_pages = ((&vdso64_end - &vdso64_start 321 + PAGE_SIZE - 1) >> PAGE_SHIFT) + 1; 322 323 /* Make sure pages are in the correct state */ 324 vdso64_pagelist = kzalloc(sizeof(struct page *) * (vdso64_pages + 1), 325 GFP_KERNEL); 326 BUG_ON(vdso64_pagelist == NULL); 327 for (i = 0; i < vdso64_pages - 1; i++) { 328 struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE); 329 ClearPageReserved(pg); 330 get_page(pg); 331 vdso64_pagelist[i] = pg; 332 } 333 vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data); 334 vdso64_pagelist[vdso64_pages] = NULL; 335 #ifndef CONFIG_SMP 336 if (vdso_alloc_per_cpu(0, &S390_lowcore)) 337 BUG(); 338 #endif 339 vdso_init_cr5(); 340 #endif /* CONFIG_64BIT */ 341 342 get_page(virt_to_page(vdso_data)); 343 344 smp_wmb(); 345 346 return 0; 347 } 348 arch_initcall(vdso_init); 349 350 int in_gate_area_no_task(unsigned long addr) 351 { 352 return 0; 353 } 354 355 int in_gate_area(struct task_struct *task, unsigned long addr) 356 { 357 return 0; 358 } 359 360 struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 361 { 362 return NULL; 363 } 364