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