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