1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * fault.c: Page fault handlers for the Sparc. 4 * 5 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) 6 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be) 7 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz) 8 */ 9 10 #include <asm/head.h> 11 12 #include <linux/string.h> 13 #include <linux/types.h> 14 #include <linux/sched.h> 15 #include <linux/ptrace.h> 16 #include <linux/mman.h> 17 #include <linux/threads.h> 18 #include <linux/kernel.h> 19 #include <linux/signal.h> 20 #include <linux/mm.h> 21 #include <linux/smp.h> 22 #include <linux/perf_event.h> 23 #include <linux/interrupt.h> 24 #include <linux/kdebug.h> 25 #include <linux/uaccess.h> 26 27 #include <asm/page.h> 28 #include <asm/pgtable.h> 29 #include <asm/openprom.h> 30 #include <asm/oplib.h> 31 #include <asm/setup.h> 32 #include <asm/smp.h> 33 #include <asm/traps.h> 34 35 #include "mm_32.h" 36 37 int show_unhandled_signals = 1; 38 39 static void __noreturn unhandled_fault(unsigned long address, 40 struct task_struct *tsk, 41 struct pt_regs *regs) 42 { 43 if ((unsigned long) address < PAGE_SIZE) { 44 printk(KERN_ALERT 45 "Unable to handle kernel NULL pointer dereference\n"); 46 } else { 47 printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n", 48 address); 49 } 50 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n", 51 (tsk->mm ? tsk->mm->context : tsk->active_mm->context)); 52 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n", 53 (tsk->mm ? (unsigned long) tsk->mm->pgd : 54 (unsigned long) tsk->active_mm->pgd)); 55 die_if_kernel("Oops", regs); 56 } 57 58 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc, 59 unsigned long address) 60 { 61 struct pt_regs regs; 62 unsigned long g2; 63 unsigned int insn; 64 int i; 65 66 i = search_extables_range(ret_pc, &g2); 67 switch (i) { 68 case 3: 69 /* load & store will be handled by fixup */ 70 return 3; 71 72 case 1: 73 /* store will be handled by fixup, load will bump out */ 74 /* for _to_ macros */ 75 insn = *((unsigned int *) pc); 76 if ((insn >> 21) & 1) 77 return 1; 78 break; 79 80 case 2: 81 /* load will be handled by fixup, store will bump out */ 82 /* for _from_ macros */ 83 insn = *((unsigned int *) pc); 84 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15) 85 return 2; 86 break; 87 88 default: 89 break; 90 } 91 92 memset(®s, 0, sizeof(regs)); 93 regs.pc = pc; 94 regs.npc = pc + 4; 95 __asm__ __volatile__( 96 "rd %%psr, %0\n\t" 97 "nop\n\t" 98 "nop\n\t" 99 "nop\n" : "=r" (regs.psr)); 100 unhandled_fault(address, current, ®s); 101 102 /* Not reached */ 103 return 0; 104 } 105 106 static inline void 107 show_signal_msg(struct pt_regs *regs, int sig, int code, 108 unsigned long address, struct task_struct *tsk) 109 { 110 if (!unhandled_signal(tsk, sig)) 111 return; 112 113 if (!printk_ratelimit()) 114 return; 115 116 printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x", 117 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, 118 tsk->comm, task_pid_nr(tsk), address, 119 (void *)regs->pc, (void *)regs->u_regs[UREG_I7], 120 (void *)regs->u_regs[UREG_FP], code); 121 122 print_vma_addr(KERN_CONT " in ", regs->pc); 123 124 printk(KERN_CONT "\n"); 125 } 126 127 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs, 128 unsigned long addr) 129 { 130 siginfo_t info; 131 132 info.si_signo = sig; 133 info.si_code = code; 134 info.si_errno = 0; 135 info.si_addr = (void __user *) addr; 136 info.si_trapno = 0; 137 138 if (unlikely(show_unhandled_signals)) 139 show_signal_msg(regs, sig, info.si_code, 140 addr, current); 141 142 force_sig_info (sig, &info, current); 143 } 144 145 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault) 146 { 147 unsigned int insn; 148 149 if (text_fault) 150 return regs->pc; 151 152 if (regs->psr & PSR_PS) 153 insn = *(unsigned int *) regs->pc; 154 else 155 __get_user(insn, (unsigned int *) regs->pc); 156 157 return safe_compute_effective_address(regs, insn); 158 } 159 160 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 161 int text_fault) 162 { 163 unsigned long addr = compute_si_addr(regs, text_fault); 164 165 __do_fault_siginfo(code, sig, regs, addr); 166 } 167 168 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write, 169 unsigned long address) 170 { 171 struct vm_area_struct *vma; 172 struct task_struct *tsk = current; 173 struct mm_struct *mm = tsk->mm; 174 unsigned int fixup; 175 unsigned long g2; 176 int from_user = !(regs->psr & PSR_PS); 177 int fault, code; 178 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 179 180 if (text_fault) 181 address = regs->pc; 182 183 /* 184 * We fault-in kernel-space virtual memory on-demand. The 185 * 'reference' page table is init_mm.pgd. 186 * 187 * NOTE! We MUST NOT take any locks for this case. We may 188 * be in an interrupt or a critical region, and should 189 * only copy the information from the master page table, 190 * nothing more. 191 */ 192 code = SEGV_MAPERR; 193 if (address >= TASK_SIZE) 194 goto vmalloc_fault; 195 196 /* 197 * If we're in an interrupt or have no user 198 * context, we must not take the fault.. 199 */ 200 if (pagefault_disabled() || !mm) 201 goto no_context; 202 203 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 204 205 retry: 206 down_read(&mm->mmap_sem); 207 208 if (!from_user && address >= PAGE_OFFSET) 209 goto bad_area; 210 211 vma = find_vma(mm, address); 212 if (!vma) 213 goto bad_area; 214 if (vma->vm_start <= address) 215 goto good_area; 216 if (!(vma->vm_flags & VM_GROWSDOWN)) 217 goto bad_area; 218 if (expand_stack(vma, address)) 219 goto bad_area; 220 /* 221 * Ok, we have a good vm_area for this memory access, so 222 * we can handle it.. 223 */ 224 good_area: 225 code = SEGV_ACCERR; 226 if (write) { 227 if (!(vma->vm_flags & VM_WRITE)) 228 goto bad_area; 229 } else { 230 /* Allow reads even for write-only mappings */ 231 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 232 goto bad_area; 233 } 234 235 if (from_user) 236 flags |= FAULT_FLAG_USER; 237 if (write) 238 flags |= FAULT_FLAG_WRITE; 239 240 /* 241 * If for any reason at all we couldn't handle the fault, 242 * make sure we exit gracefully rather than endlessly redo 243 * the fault. 244 */ 245 fault = handle_mm_fault(vma, address, flags); 246 247 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 248 return; 249 250 if (unlikely(fault & VM_FAULT_ERROR)) { 251 if (fault & VM_FAULT_OOM) 252 goto out_of_memory; 253 else if (fault & VM_FAULT_SIGSEGV) 254 goto bad_area; 255 else if (fault & VM_FAULT_SIGBUS) 256 goto do_sigbus; 257 BUG(); 258 } 259 260 if (flags & FAULT_FLAG_ALLOW_RETRY) { 261 if (fault & VM_FAULT_MAJOR) { 262 current->maj_flt++; 263 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 264 1, regs, address); 265 } else { 266 current->min_flt++; 267 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 268 1, regs, address); 269 } 270 if (fault & VM_FAULT_RETRY) { 271 flags &= ~FAULT_FLAG_ALLOW_RETRY; 272 flags |= FAULT_FLAG_TRIED; 273 274 /* No need to up_read(&mm->mmap_sem) as we would 275 * have already released it in __lock_page_or_retry 276 * in mm/filemap.c. 277 */ 278 279 goto retry; 280 } 281 } 282 283 up_read(&mm->mmap_sem); 284 return; 285 286 /* 287 * Something tried to access memory that isn't in our memory map.. 288 * Fix it, but check if it's kernel or user first.. 289 */ 290 bad_area: 291 up_read(&mm->mmap_sem); 292 293 bad_area_nosemaphore: 294 /* User mode accesses just cause a SIGSEGV */ 295 if (from_user) { 296 do_fault_siginfo(code, SIGSEGV, regs, text_fault); 297 return; 298 } 299 300 /* Is this in ex_table? */ 301 no_context: 302 g2 = regs->u_regs[UREG_G2]; 303 if (!from_user) { 304 fixup = search_extables_range(regs->pc, &g2); 305 /* Values below 10 are reserved for other things */ 306 if (fixup > 10) { 307 extern const unsigned int __memset_start[]; 308 extern const unsigned int __memset_end[]; 309 extern const unsigned int __csum_partial_copy_start[]; 310 extern const unsigned int __csum_partial_copy_end[]; 311 312 #ifdef DEBUG_EXCEPTIONS 313 printk("Exception: PC<%08lx> faddr<%08lx>\n", 314 regs->pc, address); 315 printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n", 316 regs->pc, fixup, g2); 317 #endif 318 if ((regs->pc >= (unsigned long)__memset_start && 319 regs->pc < (unsigned long)__memset_end) || 320 (regs->pc >= (unsigned long)__csum_partial_copy_start && 321 regs->pc < (unsigned long)__csum_partial_copy_end)) { 322 regs->u_regs[UREG_I4] = address; 323 regs->u_regs[UREG_I5] = regs->pc; 324 } 325 regs->u_regs[UREG_G2] = g2; 326 regs->pc = fixup; 327 regs->npc = regs->pc + 4; 328 return; 329 } 330 } 331 332 unhandled_fault(address, tsk, regs); 333 do_exit(SIGKILL); 334 335 /* 336 * We ran out of memory, or some other thing happened to us that made 337 * us unable to handle the page fault gracefully. 338 */ 339 out_of_memory: 340 up_read(&mm->mmap_sem); 341 if (from_user) { 342 pagefault_out_of_memory(); 343 return; 344 } 345 goto no_context; 346 347 do_sigbus: 348 up_read(&mm->mmap_sem); 349 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault); 350 if (!from_user) 351 goto no_context; 352 353 vmalloc_fault: 354 { 355 /* 356 * Synchronize this task's top level page-table 357 * with the 'reference' page table. 358 */ 359 int offset = pgd_index(address); 360 pgd_t *pgd, *pgd_k; 361 pmd_t *pmd, *pmd_k; 362 363 pgd = tsk->active_mm->pgd + offset; 364 pgd_k = init_mm.pgd + offset; 365 366 if (!pgd_present(*pgd)) { 367 if (!pgd_present(*pgd_k)) 368 goto bad_area_nosemaphore; 369 pgd_val(*pgd) = pgd_val(*pgd_k); 370 return; 371 } 372 373 pmd = pmd_offset(pgd, address); 374 pmd_k = pmd_offset(pgd_k, address); 375 376 if (pmd_present(*pmd) || !pmd_present(*pmd_k)) 377 goto bad_area_nosemaphore; 378 379 *pmd = *pmd_k; 380 return; 381 } 382 } 383 384 /* This always deals with user addresses. */ 385 static void force_user_fault(unsigned long address, int write) 386 { 387 struct vm_area_struct *vma; 388 struct task_struct *tsk = current; 389 struct mm_struct *mm = tsk->mm; 390 unsigned int flags = FAULT_FLAG_USER; 391 int code; 392 393 code = SEGV_MAPERR; 394 395 down_read(&mm->mmap_sem); 396 vma = find_vma(mm, address); 397 if (!vma) 398 goto bad_area; 399 if (vma->vm_start <= address) 400 goto good_area; 401 if (!(vma->vm_flags & VM_GROWSDOWN)) 402 goto bad_area; 403 if (expand_stack(vma, address)) 404 goto bad_area; 405 good_area: 406 code = SEGV_ACCERR; 407 if (write) { 408 if (!(vma->vm_flags & VM_WRITE)) 409 goto bad_area; 410 flags |= FAULT_FLAG_WRITE; 411 } else { 412 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 413 goto bad_area; 414 } 415 switch (handle_mm_fault(vma, address, flags)) { 416 case VM_FAULT_SIGBUS: 417 case VM_FAULT_OOM: 418 goto do_sigbus; 419 } 420 up_read(&mm->mmap_sem); 421 return; 422 bad_area: 423 up_read(&mm->mmap_sem); 424 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address); 425 return; 426 427 do_sigbus: 428 up_read(&mm->mmap_sem); 429 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address); 430 } 431 432 static void check_stack_aligned(unsigned long sp) 433 { 434 if (sp & 0x7UL) 435 force_sig(SIGILL, current); 436 } 437 438 void window_overflow_fault(void) 439 { 440 unsigned long sp; 441 442 sp = current_thread_info()->rwbuf_stkptrs[0]; 443 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 444 force_user_fault(sp + 0x38, 1); 445 force_user_fault(sp, 1); 446 447 check_stack_aligned(sp); 448 } 449 450 void window_underflow_fault(unsigned long sp) 451 { 452 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 453 force_user_fault(sp + 0x38, 0); 454 force_user_fault(sp, 0); 455 456 check_stack_aligned(sp); 457 } 458 459 void window_ret_fault(struct pt_regs *regs) 460 { 461 unsigned long sp; 462 463 sp = regs->u_regs[UREG_FP]; 464 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) 465 force_user_fault(sp + 0x38, 0); 466 force_user_fault(sp, 0); 467 468 check_stack_aligned(sp); 469 } 470