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