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