1 /* 2 * fault.c: Page fault handlers for the Sparc. 3 * 4 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) 5 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be) 6 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz) 7 */ 8 9 #include <asm/head.h> 10 11 #include <linux/string.h> 12 #include <linux/types.h> 13 #include <linux/sched.h> 14 #include <linux/ptrace.h> 15 #include <linux/mman.h> 16 #include <linux/threads.h> 17 #include <linux/kernel.h> 18 #include <linux/signal.h> 19 #include <linux/mm.h> 20 #include <linux/smp.h> 21 #include <linux/perf_event.h> 22 #include <linux/interrupt.h> 23 #include <linux/kdebug.h> 24 #include <linux/uaccess.h> 25 26 #include <asm/page.h> 27 #include <asm/pgtable.h> 28 #include <asm/openprom.h> 29 #include <asm/oplib.h> 30 #include <asm/setup.h> 31 #include <asm/smp.h> 32 #include <asm/traps.h> 33 34 #include "mm_32.h" 35 36 int show_unhandled_signals = 1; 37 38 static void __noreturn unhandled_fault(unsigned long address, 39 struct task_struct *tsk, 40 struct pt_regs *regs) 41 { 42 if ((unsigned long) address < PAGE_SIZE) { 43 printk(KERN_ALERT 44 "Unable to handle kernel NULL pointer dereference\n"); 45 } else { 46 printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n", 47 address); 48 } 49 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n", 50 (tsk->mm ? tsk->mm->context : tsk->active_mm->context)); 51 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n", 52 (tsk->mm ? (unsigned long) tsk->mm->pgd : 53 (unsigned long) tsk->active_mm->pgd)); 54 die_if_kernel("Oops", regs); 55 } 56 57 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc, 58 unsigned long address) 59 { 60 struct pt_regs regs; 61 unsigned long g2; 62 unsigned int insn; 63 int i; 64 65 i = search_extables_range(ret_pc, &g2); 66 switch (i) { 67 case 3: 68 /* load & store will be handled by fixup */ 69 return 3; 70 71 case 1: 72 /* store will be handled by fixup, load will bump out */ 73 /* for _to_ macros */ 74 insn = *((unsigned int *) pc); 75 if ((insn >> 21) & 1) 76 return 1; 77 break; 78 79 case 2: 80 /* load will be handled by fixup, store will bump out */ 81 /* for _from_ macros */ 82 insn = *((unsigned int *) pc); 83 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15) 84 return 2; 85 break; 86 87 default: 88 break; 89 } 90 91 memset(®s, 0, sizeof(regs)); 92 regs.pc = pc; 93 regs.npc = pc + 4; 94 __asm__ __volatile__( 95 "rd %%psr, %0\n\t" 96 "nop\n\t" 97 "nop\n\t" 98 "nop\n" : "=r" (regs.psr)); 99 unhandled_fault(address, current, ®s); 100 101 /* Not reached */ 102 return 0; 103 } 104 105 static inline void 106 show_signal_msg(struct pt_regs *regs, int sig, int code, 107 unsigned long address, struct task_struct *tsk) 108 { 109 if (!unhandled_signal(tsk, sig)) 110 return; 111 112 if (!printk_ratelimit()) 113 return; 114 115 printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x", 116 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, 117 tsk->comm, task_pid_nr(tsk), address, 118 (void *)regs->pc, (void *)regs->u_regs[UREG_I7], 119 (void *)regs->u_regs[UREG_FP], code); 120 121 print_vma_addr(KERN_CONT " in ", regs->pc); 122 123 printk(KERN_CONT "\n"); 124 } 125 126 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs, 127 unsigned long addr) 128 { 129 siginfo_t info; 130 131 info.si_signo = sig; 132 info.si_code = code; 133 info.si_errno = 0; 134 info.si_addr = (void __user *) addr; 135 info.si_trapno = 0; 136 137 if (unlikely(show_unhandled_signals)) 138 show_signal_msg(regs, sig, info.si_code, 139 addr, current); 140 141 force_sig_info (sig, &info, current); 142 } 143 144 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault) 145 { 146 unsigned int insn; 147 148 if (text_fault) 149 return regs->pc; 150 151 if (regs->psr & PSR_PS) 152 insn = *(unsigned int *) regs->pc; 153 else 154 __get_user(insn, (unsigned int *) regs->pc); 155 156 return safe_compute_effective_address(regs, insn); 157 } 158 159 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 160 int text_fault) 161 { 162 unsigned long addr = compute_si_addr(regs, text_fault); 163 164 __do_fault_siginfo(code, sig, regs, addr); 165 } 166 167 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write, 168 unsigned long address) 169 { 170 struct vm_area_struct *vma; 171 struct task_struct *tsk = current; 172 struct mm_struct *mm = tsk->mm; 173 unsigned int fixup; 174 unsigned long g2; 175 int from_user = !(regs->psr & PSR_PS); 176 int fault, code; 177 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 178 179 if (text_fault) 180 address = regs->pc; 181 182 /* 183 * We fault-in kernel-space virtual memory on-demand. The 184 * 'reference' page table is init_mm.pgd. 185 * 186 * NOTE! We MUST NOT take any locks for this case. We may 187 * be in an interrupt or a critical region, and should 188 * only copy the information from the master page table, 189 * nothing more. 190 */ 191 code = SEGV_MAPERR; 192 if (address >= TASK_SIZE) 193 goto vmalloc_fault; 194 195 /* 196 * If we're in an interrupt or have no user 197 * context, we must not take the fault.. 198 */ 199 if (pagefault_disabled() || !mm) 200 goto no_context; 201 202 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 203 204 retry: 205 down_read(&mm->mmap_sem); 206 207 if (!from_user && address >= PAGE_OFFSET) 208 goto bad_area; 209 210 vma = find_vma(mm, address); 211 if (!vma) 212 goto bad_area; 213 if (vma->vm_start <= address) 214 goto good_area; 215 if (!(vma->vm_flags & VM_GROWSDOWN)) 216 goto bad_area; 217 if (expand_stack(vma, address)) 218 goto bad_area; 219 /* 220 * Ok, we have a good vm_area for this memory access, so 221 * we can handle it.. 222 */ 223 good_area: 224 code = SEGV_ACCERR; 225 if (write) { 226 if (!(vma->vm_flags & VM_WRITE)) 227 goto bad_area; 228 } else { 229 /* Allow reads even for write-only mappings */ 230 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 231 goto bad_area; 232 } 233 234 if (from_user) 235 flags |= FAULT_FLAG_USER; 236 if (write) 237 flags |= FAULT_FLAG_WRITE; 238 239 /* 240 * If for any reason at all we couldn't handle the fault, 241 * make sure we exit gracefully rather than endlessly redo 242 * the fault. 243 */ 244 fault = handle_mm_fault(mm, vma, address, flags); 245 246 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 247 return; 248 249 if (unlikely(fault & VM_FAULT_ERROR)) { 250 if (fault & VM_FAULT_OOM) 251 goto out_of_memory; 252 else if (fault & VM_FAULT_SIGSEGV) 253 goto bad_area; 254 else if (fault & VM_FAULT_SIGBUS) 255 goto do_sigbus; 256 BUG(); 257 } 258 259 if (flags & FAULT_FLAG_ALLOW_RETRY) { 260 if (fault & VM_FAULT_MAJOR) { 261 current->maj_flt++; 262 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 263 1, regs, address); 264 } else { 265 current->min_flt++; 266 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 267 1, regs, address); 268 } 269 if (fault & VM_FAULT_RETRY) { 270 flags &= ~FAULT_FLAG_ALLOW_RETRY; 271 flags |= FAULT_FLAG_TRIED; 272 273 /* No need to up_read(&mm->mmap_sem) as we would 274 * have already released it in __lock_page_or_retry 275 * in mm/filemap.c. 276 */ 277 278 goto retry; 279 } 280 } 281 282 up_read(&mm->mmap_sem); 283 return; 284 285 /* 286 * Something tried to access memory that isn't in our memory map.. 287 * Fix it, but check if it's kernel or user first.. 288 */ 289 bad_area: 290 up_read(&mm->mmap_sem); 291 292 bad_area_nosemaphore: 293 /* User mode accesses just cause a SIGSEGV */ 294 if (from_user) { 295 do_fault_siginfo(code, SIGSEGV, regs, text_fault); 296 return; 297 } 298 299 /* Is this in ex_table? */ 300 no_context: 301 g2 = regs->u_regs[UREG_G2]; 302 if (!from_user) { 303 fixup = search_extables_range(regs->pc, &g2); 304 /* Values below 10 are reserved for other things */ 305 if (fixup > 10) { 306 extern const unsigned int __memset_start[]; 307 extern const unsigned int __memset_end[]; 308 extern const unsigned int __csum_partial_copy_start[]; 309 extern const unsigned int __csum_partial_copy_end[]; 310 311 #ifdef DEBUG_EXCEPTIONS 312 printk("Exception: PC<%08lx> faddr<%08lx>\n", 313 regs->pc, address); 314 printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n", 315 regs->pc, fixup, g2); 316 #endif 317 if ((regs->pc >= (unsigned long)__memset_start && 318 regs->pc < (unsigned long)__memset_end) || 319 (regs->pc >= (unsigned long)__csum_partial_copy_start && 320 regs->pc < (unsigned long)__csum_partial_copy_end)) { 321 regs->u_regs[UREG_I4] = address; 322 regs->u_regs[UREG_I5] = regs->pc; 323 } 324 regs->u_regs[UREG_G2] = g2; 325 regs->pc = fixup; 326 regs->npc = regs->pc + 4; 327 return; 328 } 329 } 330 331 unhandled_fault(address, tsk, regs); 332 do_exit(SIGKILL); 333 334 /* 335 * We ran out of memory, or some other thing happened to us that made 336 * us unable to handle the page fault gracefully. 337 */ 338 out_of_memory: 339 up_read(&mm->mmap_sem); 340 if (from_user) { 341 pagefault_out_of_memory(); 342 return; 343 } 344 goto no_context; 345 346 do_sigbus: 347 up_read(&mm->mmap_sem); 348 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault); 349 if (!from_user) 350 goto no_context; 351 352 vmalloc_fault: 353 { 354 /* 355 * Synchronize this task's top level page-table 356 * with the 'reference' page table. 357 */ 358 int offset = pgd_index(address); 359 pgd_t *pgd, *pgd_k; 360 pmd_t *pmd, *pmd_k; 361 362 pgd = tsk->active_mm->pgd + offset; 363 pgd_k = init_mm.pgd + offset; 364 365 if (!pgd_present(*pgd)) { 366 if (!pgd_present(*pgd_k)) 367 goto bad_area_nosemaphore; 368 pgd_val(*pgd) = pgd_val(*pgd_k); 369 return; 370 } 371 372 pmd = pmd_offset(pgd, address); 373 pmd_k = pmd_offset(pgd_k, address); 374 375 if (pmd_present(*pmd) || !pmd_present(*pmd_k)) 376 goto bad_area_nosemaphore; 377 378 *pmd = *pmd_k; 379 return; 380 } 381 } 382 383 /* This always deals with user addresses. */ 384 static void force_user_fault(unsigned long address, int write) 385 { 386 struct vm_area_struct *vma; 387 struct task_struct *tsk = current; 388 struct mm_struct *mm = tsk->mm; 389 unsigned int flags = FAULT_FLAG_USER; 390 int code; 391 392 code = SEGV_MAPERR; 393 394 down_read(&mm->mmap_sem); 395 vma = find_vma(mm, address); 396 if (!vma) 397 goto bad_area; 398 if (vma->vm_start <= address) 399 goto good_area; 400 if (!(vma->vm_flags & VM_GROWSDOWN)) 401 goto bad_area; 402 if (expand_stack(vma, address)) 403 goto bad_area; 404 good_area: 405 code = SEGV_ACCERR; 406 if (write) { 407 if (!(vma->vm_flags & VM_WRITE)) 408 goto bad_area; 409 flags |= FAULT_FLAG_WRITE; 410 } else { 411 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 412 goto bad_area; 413 } 414 switch (handle_mm_fault(mm, vma, address, flags)) { 415 case VM_FAULT_SIGBUS: 416 case VM_FAULT_OOM: 417 goto do_sigbus; 418 } 419 up_read(&mm->mmap_sem); 420 return; 421 bad_area: 422 up_read(&mm->mmap_sem); 423 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address); 424 return; 425 426 do_sigbus: 427 up_read(&mm->mmap_sem); 428 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address); 429 } 430 431 static void check_stack_aligned(unsigned long sp) 432 { 433 if (sp & 0x7UL) 434 force_sig(SIGILL, current); 435 } 436 437 void window_overflow_fault(void) 438 { 439 unsigned long sp; 440 441 sp = current_thread_info()->rwbuf_stkptrs[0]; 442 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 443 force_user_fault(sp + 0x38, 1); 444 force_user_fault(sp, 1); 445 446 check_stack_aligned(sp); 447 } 448 449 void window_underflow_fault(unsigned long sp) 450 { 451 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 452 force_user_fault(sp + 0x38, 0); 453 force_user_fault(sp, 0); 454 455 check_stack_aligned(sp); 456 } 457 458 void window_ret_fault(struct pt_regs *regs) 459 { 460 unsigned long sp; 461 462 sp = regs->u_regs[UREG_FP]; 463 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 464 force_user_fault(sp + 0x38, 0); 465 force_user_fault(sp, 0); 466 467 check_stack_aligned(sp); 468 } 469