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 if (unlikely(show_unhandled_signals)) 131 show_signal_msg(regs, sig, code, 132 addr, current); 133 134 force_sig_fault(sig, code, (void __user *) addr, 0); 135 } 136 137 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault) 138 { 139 unsigned int insn; 140 141 if (text_fault) 142 return regs->pc; 143 144 if (regs->psr & PSR_PS) 145 insn = *(unsigned int *) regs->pc; 146 else 147 __get_user(insn, (unsigned int *) regs->pc); 148 149 return safe_compute_effective_address(regs, insn); 150 } 151 152 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 153 int text_fault) 154 { 155 unsigned long addr = compute_si_addr(regs, text_fault); 156 157 __do_fault_siginfo(code, sig, regs, addr); 158 } 159 160 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write, 161 unsigned long address) 162 { 163 struct vm_area_struct *vma; 164 struct task_struct *tsk = current; 165 struct mm_struct *mm = tsk->mm; 166 unsigned int fixup; 167 unsigned long g2; 168 int from_user = !(regs->psr & PSR_PS); 169 int code; 170 vm_fault_t fault; 171 unsigned int flags = FAULT_FLAG_DEFAULT; 172 173 if (text_fault) 174 address = regs->pc; 175 176 /* 177 * We fault-in kernel-space virtual memory on-demand. The 178 * 'reference' page table is init_mm.pgd. 179 * 180 * NOTE! We MUST NOT take any locks for this case. We may 181 * be in an interrupt or a critical region, and should 182 * only copy the information from the master page table, 183 * nothing more. 184 */ 185 code = SEGV_MAPERR; 186 if (address >= TASK_SIZE) 187 goto vmalloc_fault; 188 189 /* 190 * If we're in an interrupt or have no user 191 * context, we must not take the fault.. 192 */ 193 if (pagefault_disabled() || !mm) 194 goto no_context; 195 196 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 197 198 retry: 199 down_read(&mm->mmap_sem); 200 201 if (!from_user && address >= PAGE_OFFSET) 202 goto bad_area; 203 204 vma = find_vma(mm, address); 205 if (!vma) 206 goto bad_area; 207 if (vma->vm_start <= address) 208 goto good_area; 209 if (!(vma->vm_flags & VM_GROWSDOWN)) 210 goto bad_area; 211 if (expand_stack(vma, address)) 212 goto bad_area; 213 /* 214 * Ok, we have a good vm_area for this memory access, so 215 * we can handle it.. 216 */ 217 good_area: 218 code = SEGV_ACCERR; 219 if (write) { 220 if (!(vma->vm_flags & VM_WRITE)) 221 goto bad_area; 222 } else { 223 /* Allow reads even for write-only mappings */ 224 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 225 goto bad_area; 226 } 227 228 if (from_user) 229 flags |= FAULT_FLAG_USER; 230 if (write) 231 flags |= FAULT_FLAG_WRITE; 232 233 /* 234 * If for any reason at all we couldn't handle the fault, 235 * make sure we exit gracefully rather than endlessly redo 236 * the fault. 237 */ 238 fault = handle_mm_fault(vma, address, flags); 239 240 if (fault_signal_pending(fault, regs)) 241 return; 242 243 if (unlikely(fault & VM_FAULT_ERROR)) { 244 if (fault & VM_FAULT_OOM) 245 goto out_of_memory; 246 else if (fault & VM_FAULT_SIGSEGV) 247 goto bad_area; 248 else if (fault & VM_FAULT_SIGBUS) 249 goto do_sigbus; 250 BUG(); 251 } 252 253 if (flags & FAULT_FLAG_ALLOW_RETRY) { 254 if (fault & VM_FAULT_MAJOR) { 255 current->maj_flt++; 256 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 257 1, regs, address); 258 } else { 259 current->min_flt++; 260 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 261 1, regs, address); 262 } 263 if (fault & VM_FAULT_RETRY) { 264 flags |= FAULT_FLAG_TRIED; 265 266 /* No need to up_read(&mm->mmap_sem) as we would 267 * have already released it in __lock_page_or_retry 268 * in mm/filemap.c. 269 */ 270 271 goto retry; 272 } 273 } 274 275 up_read(&mm->mmap_sem); 276 return; 277 278 /* 279 * Something tried to access memory that isn't in our memory map.. 280 * Fix it, but check if it's kernel or user first.. 281 */ 282 bad_area: 283 up_read(&mm->mmap_sem); 284 285 bad_area_nosemaphore: 286 /* User mode accesses just cause a SIGSEGV */ 287 if (from_user) { 288 do_fault_siginfo(code, SIGSEGV, regs, text_fault); 289 return; 290 } 291 292 /* Is this in ex_table? */ 293 no_context: 294 g2 = regs->u_regs[UREG_G2]; 295 if (!from_user) { 296 fixup = search_extables_range(regs->pc, &g2); 297 /* Values below 10 are reserved for other things */ 298 if (fixup > 10) { 299 extern const unsigned int __memset_start[]; 300 extern const unsigned int __memset_end[]; 301 extern const unsigned int __csum_partial_copy_start[]; 302 extern const unsigned int __csum_partial_copy_end[]; 303 304 #ifdef DEBUG_EXCEPTIONS 305 printk("Exception: PC<%08lx> faddr<%08lx>\n", 306 regs->pc, address); 307 printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n", 308 regs->pc, fixup, g2); 309 #endif 310 if ((regs->pc >= (unsigned long)__memset_start && 311 regs->pc < (unsigned long)__memset_end) || 312 (regs->pc >= (unsigned long)__csum_partial_copy_start && 313 regs->pc < (unsigned long)__csum_partial_copy_end)) { 314 regs->u_regs[UREG_I4] = address; 315 regs->u_regs[UREG_I5] = regs->pc; 316 } 317 regs->u_regs[UREG_G2] = g2; 318 regs->pc = fixup; 319 regs->npc = regs->pc + 4; 320 return; 321 } 322 } 323 324 unhandled_fault(address, tsk, regs); 325 do_exit(SIGKILL); 326 327 /* 328 * We ran out of memory, or some other thing happened to us that made 329 * us unable to handle the page fault gracefully. 330 */ 331 out_of_memory: 332 up_read(&mm->mmap_sem); 333 if (from_user) { 334 pagefault_out_of_memory(); 335 return; 336 } 337 goto no_context; 338 339 do_sigbus: 340 up_read(&mm->mmap_sem); 341 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault); 342 if (!from_user) 343 goto no_context; 344 345 vmalloc_fault: 346 { 347 /* 348 * Synchronize this task's top level page-table 349 * with the 'reference' page table. 350 */ 351 int offset = pgd_index(address); 352 pgd_t *pgd, *pgd_k; 353 p4d_t *p4d, *p4d_k; 354 pud_t *pud, *pud_k; 355 pmd_t *pmd, *pmd_k; 356 357 pgd = tsk->active_mm->pgd + offset; 358 pgd_k = init_mm.pgd + offset; 359 360 if (!pgd_present(*pgd)) { 361 if (!pgd_present(*pgd_k)) 362 goto bad_area_nosemaphore; 363 pgd_val(*pgd) = pgd_val(*pgd_k); 364 return; 365 } 366 367 p4d = p4d_offset(pgd, address); 368 pud = pud_offset(p4d, address); 369 pmd = pmd_offset(pud, address); 370 371 p4d_k = p4d_offset(pgd_k, address); 372 pud_k = pud_offset(p4d_k, address); 373 pmd_k = pmd_offset(pud_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(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); 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