1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * 7 * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle 8 * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org) 9 * Copyright 1999 Hewlett Packard Co. 10 * 11 */ 12 13 #include <linux/mm.h> 14 #include <linux/ptrace.h> 15 #include <linux/sched.h> 16 #include <linux/sched/debug.h> 17 #include <linux/interrupt.h> 18 #include <linux/extable.h> 19 #include <linux/uaccess.h> 20 #include <linux/hugetlb.h> 21 #include <linux/perf_event.h> 22 23 #include <asm/traps.h> 24 25 #define DEBUG_NATLB 0 26 27 /* Various important other fields */ 28 #define bit22set(x) (x & 0x00000200) 29 #define bits23_25set(x) (x & 0x000001c0) 30 #define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80) 31 /* extended opcode is 0x6a */ 32 33 #define BITSSET 0x1c0 /* for identifying LDCW */ 34 35 36 int show_unhandled_signals = 1; 37 38 /* 39 * parisc_acctyp(unsigned int inst) -- 40 * Given a PA-RISC memory access instruction, determine if the 41 * instruction would perform a memory read or memory write 42 * operation. 43 * 44 * This function assumes that the given instruction is a memory access 45 * instruction (i.e. you should really only call it if you know that 46 * the instruction has generated some sort of a memory access fault). 47 * 48 * Returns: 49 * VM_READ if read operation 50 * VM_WRITE if write operation 51 * VM_EXEC if execute operation 52 */ 53 unsigned long 54 parisc_acctyp(unsigned long code, unsigned int inst) 55 { 56 if (code == 6 || code == 16) 57 return VM_EXEC; 58 59 switch (inst & 0xf0000000) { 60 case 0x40000000: /* load */ 61 case 0x50000000: /* new load */ 62 return VM_READ; 63 64 case 0x60000000: /* store */ 65 case 0x70000000: /* new store */ 66 return VM_WRITE; 67 68 case 0x20000000: /* coproc */ 69 case 0x30000000: /* coproc2 */ 70 if (bit22set(inst)) 71 return VM_WRITE; 72 fallthrough; 73 74 case 0x0: /* indexed/memory management */ 75 if (bit22set(inst)) { 76 /* 77 * Check for the 'Graphics Flush Read' instruction. 78 * It resembles an FDC instruction, except for bits 79 * 20 and 21. Any combination other than zero will 80 * utilize the block mover functionality on some 81 * older PA-RISC platforms. The case where a block 82 * move is performed from VM to graphics IO space 83 * should be treated as a READ. 84 * 85 * The significance of bits 20,21 in the FDC 86 * instruction is: 87 * 88 * 00 Flush data cache (normal instruction behavior) 89 * 01 Graphics flush write (IO space -> VM) 90 * 10 Graphics flush read (VM -> IO space) 91 * 11 Graphics flush read/write (VM <-> IO space) 92 */ 93 if (isGraphicsFlushRead(inst)) 94 return VM_READ; 95 return VM_WRITE; 96 } else { 97 /* 98 * Check for LDCWX and LDCWS (semaphore instructions). 99 * If bits 23 through 25 are all 1's it is one of 100 * the above two instructions and is a write. 101 * 102 * Note: With the limited bits we are looking at, 103 * this will also catch PROBEW and PROBEWI. However, 104 * these should never get in here because they don't 105 * generate exceptions of the type: 106 * Data TLB miss fault/data page fault 107 * Data memory protection trap 108 */ 109 if (bits23_25set(inst) == BITSSET) 110 return VM_WRITE; 111 } 112 return VM_READ; /* Default */ 113 } 114 return VM_READ; /* Default */ 115 } 116 117 #undef bit22set 118 #undef bits23_25set 119 #undef isGraphicsFlushRead 120 #undef BITSSET 121 122 123 #if 0 124 /* This is the treewalk to find a vma which is the highest that has 125 * a start < addr. We're using find_vma_prev instead right now, but 126 * we might want to use this at some point in the future. Probably 127 * not, but I want it committed to CVS so I don't lose it :-) 128 */ 129 while (tree != vm_avl_empty) { 130 if (tree->vm_start > addr) { 131 tree = tree->vm_avl_left; 132 } else { 133 prev = tree; 134 if (prev->vm_next == NULL) 135 break; 136 if (prev->vm_next->vm_start > addr) 137 break; 138 tree = tree->vm_avl_right; 139 } 140 } 141 #endif 142 143 int fixup_exception(struct pt_regs *regs) 144 { 145 const struct exception_table_entry *fix; 146 147 fix = search_exception_tables(regs->iaoq[0]); 148 if (fix) { 149 /* 150 * Fix up get_user() and put_user(). 151 * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() sets the least-significant 152 * bit in the relative address of the fixup routine to indicate 153 * that gr[ASM_EXCEPTIONTABLE_REG] should be loaded with 154 * -EFAULT to report a userspace access error. 155 */ 156 if (fix->fixup & 1) { 157 regs->gr[ASM_EXCEPTIONTABLE_REG] = -EFAULT; 158 159 /* zero target register for get_user() */ 160 if (parisc_acctyp(0, regs->iir) == VM_READ) { 161 int treg = regs->iir & 0x1f; 162 BUG_ON(treg == 0); 163 regs->gr[treg] = 0; 164 } 165 } 166 167 regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup; 168 regs->iaoq[0] &= ~3; 169 /* 170 * NOTE: In some cases the faulting instruction 171 * may be in the delay slot of a branch. We 172 * don't want to take the branch, so we don't 173 * increment iaoq[1], instead we set it to be 174 * iaoq[0]+4, and clear the B bit in the PSW 175 */ 176 regs->iaoq[1] = regs->iaoq[0] + 4; 177 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */ 178 179 return 1; 180 } 181 182 return 0; 183 } 184 185 /* 186 * parisc hardware trap list 187 * 188 * Documented in section 3 "Addressing and Access Control" of the 189 * "PA-RISC 1.1 Architecture and Instruction Set Reference Manual" 190 * https://parisc.wiki.kernel.org/index.php/File:Pa11_acd.pdf 191 * 192 * For implementation see handle_interruption() in traps.c 193 */ 194 static const char * const trap_description[] = { 195 [1] "High-priority machine check (HPMC)", 196 [2] "Power failure interrupt", 197 [3] "Recovery counter trap", 198 [5] "Low-priority machine check", 199 [6] "Instruction TLB miss fault", 200 [7] "Instruction access rights / protection trap", 201 [8] "Illegal instruction trap", 202 [9] "Break instruction trap", 203 [10] "Privileged operation trap", 204 [11] "Privileged register trap", 205 [12] "Overflow trap", 206 [13] "Conditional trap", 207 [14] "FP Assist Exception trap", 208 [15] "Data TLB miss fault", 209 [16] "Non-access ITLB miss fault", 210 [17] "Non-access DTLB miss fault", 211 [18] "Data memory protection/unaligned access trap", 212 [19] "Data memory break trap", 213 [20] "TLB dirty bit trap", 214 [21] "Page reference trap", 215 [22] "Assist emulation trap", 216 [25] "Taken branch trap", 217 [26] "Data memory access rights trap", 218 [27] "Data memory protection ID trap", 219 [28] "Unaligned data reference trap", 220 }; 221 222 const char *trap_name(unsigned long code) 223 { 224 const char *t = NULL; 225 226 if (code < ARRAY_SIZE(trap_description)) 227 t = trap_description[code]; 228 229 return t ? t : "Unknown trap"; 230 } 231 232 /* 233 * Print out info about fatal segfaults, if the show_unhandled_signals 234 * sysctl is set: 235 */ 236 static inline void 237 show_signal_msg(struct pt_regs *regs, unsigned long code, 238 unsigned long address, struct task_struct *tsk, 239 struct vm_area_struct *vma) 240 { 241 if (!unhandled_signal(tsk, SIGSEGV)) 242 return; 243 244 if (!printk_ratelimit()) 245 return; 246 247 pr_warn("\n"); 248 pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx", 249 tsk->comm, code, address); 250 print_vma_addr(KERN_CONT " in ", regs->iaoq[0]); 251 252 pr_cont("\ntrap #%lu: %s%c", code, trap_name(code), 253 vma ? ',':'\n'); 254 255 if (vma) 256 pr_cont(" vm_start = 0x%08lx, vm_end = 0x%08lx\n", 257 vma->vm_start, vma->vm_end); 258 259 show_regs(regs); 260 } 261 262 void do_page_fault(struct pt_regs *regs, unsigned long code, 263 unsigned long address) 264 { 265 struct vm_area_struct *vma, *prev_vma; 266 struct task_struct *tsk; 267 struct mm_struct *mm; 268 unsigned long acc_type; 269 vm_fault_t fault = 0; 270 unsigned int flags; 271 char *msg; 272 273 tsk = current; 274 mm = tsk->mm; 275 if (!mm) { 276 msg = "Page fault: no context"; 277 goto no_context; 278 } 279 280 flags = FAULT_FLAG_DEFAULT; 281 if (user_mode(regs)) 282 flags |= FAULT_FLAG_USER; 283 284 acc_type = parisc_acctyp(code, regs->iir); 285 if (acc_type & VM_WRITE) 286 flags |= FAULT_FLAG_WRITE; 287 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 288 retry: 289 mmap_read_lock(mm); 290 vma = find_vma_prev(mm, address, &prev_vma); 291 if (!vma || address < vma->vm_start) 292 goto check_expansion; 293 /* 294 * Ok, we have a good vm_area for this memory access. We still need to 295 * check the access permissions. 296 */ 297 298 good_area: 299 300 if ((vma->vm_flags & acc_type) != acc_type) 301 goto bad_area; 302 303 /* 304 * If for any reason at all we couldn't handle the fault, make 305 * sure we exit gracefully rather than endlessly redo the 306 * fault. 307 */ 308 309 fault = handle_mm_fault(vma, address, flags, regs); 310 311 if (fault_signal_pending(fault, regs)) 312 return; 313 314 /* The fault is fully completed (including releasing mmap lock) */ 315 if (fault & VM_FAULT_COMPLETED) 316 return; 317 318 if (unlikely(fault & VM_FAULT_ERROR)) { 319 /* 320 * We hit a shared mapping outside of the file, or some 321 * other thing happened to us that made us unable to 322 * handle the page fault gracefully. 323 */ 324 if (fault & VM_FAULT_OOM) 325 goto out_of_memory; 326 else if (fault & VM_FAULT_SIGSEGV) 327 goto bad_area; 328 else if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON| 329 VM_FAULT_HWPOISON_LARGE)) 330 goto bad_area; 331 BUG(); 332 } 333 if (fault & VM_FAULT_RETRY) { 334 /* 335 * No need to mmap_read_unlock(mm) as we would 336 * have already released it in __lock_page_or_retry 337 * in mm/filemap.c. 338 */ 339 flags |= FAULT_FLAG_TRIED; 340 goto retry; 341 } 342 mmap_read_unlock(mm); 343 return; 344 345 check_expansion: 346 vma = prev_vma; 347 if (vma && (expand_stack(vma, address) == 0)) 348 goto good_area; 349 350 /* 351 * Something tried to access memory that isn't in our memory map.. 352 */ 353 bad_area: 354 mmap_read_unlock(mm); 355 356 if (user_mode(regs)) { 357 int signo, si_code; 358 359 switch (code) { 360 case 15: /* Data TLB miss fault/Data page fault */ 361 /* send SIGSEGV when outside of vma */ 362 if (!vma || 363 address < vma->vm_start || address >= vma->vm_end) { 364 signo = SIGSEGV; 365 si_code = SEGV_MAPERR; 366 break; 367 } 368 369 /* send SIGSEGV for wrong permissions */ 370 if ((vma->vm_flags & acc_type) != acc_type) { 371 signo = SIGSEGV; 372 si_code = SEGV_ACCERR; 373 break; 374 } 375 376 /* probably address is outside of mapped file */ 377 fallthrough; 378 case 17: /* NA data TLB miss / page fault */ 379 case 18: /* Unaligned access - PCXS only */ 380 signo = SIGBUS; 381 si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR; 382 break; 383 case 16: /* Non-access instruction TLB miss fault */ 384 case 26: /* PCXL: Data memory access rights trap */ 385 default: 386 signo = SIGSEGV; 387 si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR; 388 break; 389 } 390 #ifdef CONFIG_MEMORY_FAILURE 391 if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) { 392 unsigned int lsb = 0; 393 printk(KERN_ERR 394 "MCE: Killing %s:%d due to hardware memory corruption fault at %08lx\n", 395 tsk->comm, tsk->pid, address); 396 /* 397 * Either small page or large page may be poisoned. 398 * In other words, VM_FAULT_HWPOISON_LARGE and 399 * VM_FAULT_HWPOISON are mutually exclusive. 400 */ 401 if (fault & VM_FAULT_HWPOISON_LARGE) 402 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); 403 else if (fault & VM_FAULT_HWPOISON) 404 lsb = PAGE_SHIFT; 405 406 force_sig_mceerr(BUS_MCEERR_AR, (void __user *) address, 407 lsb); 408 return; 409 } 410 #endif 411 show_signal_msg(regs, code, address, tsk, vma); 412 413 force_sig_fault(signo, si_code, (void __user *) address); 414 return; 415 } 416 msg = "Page fault: bad address"; 417 418 no_context: 419 420 if (!user_mode(regs) && fixup_exception(regs)) { 421 return; 422 } 423 424 parisc_terminate(msg, regs, code, address); 425 426 out_of_memory: 427 mmap_read_unlock(mm); 428 if (!user_mode(regs)) { 429 msg = "Page fault: out of memory"; 430 goto no_context; 431 } 432 pagefault_out_of_memory(); 433 } 434 435 /* Handle non-access data TLB miss faults. 436 * 437 * For probe instructions, accesses to userspace are considered allowed 438 * if they lie in a valid VMA and the access type matches. We are not 439 * allowed to handle MM faults here so there may be situations where an 440 * actual access would fail even though a probe was successful. 441 */ 442 int 443 handle_nadtlb_fault(struct pt_regs *regs) 444 { 445 unsigned long insn = regs->iir; 446 int breg, treg, xreg, val = 0; 447 struct vm_area_struct *vma, *prev_vma; 448 struct task_struct *tsk; 449 struct mm_struct *mm; 450 unsigned long address; 451 unsigned long acc_type; 452 453 switch (insn & 0x380) { 454 case 0x280: 455 /* FDC instruction */ 456 fallthrough; 457 case 0x380: 458 /* PDC and FIC instructions */ 459 if (DEBUG_NATLB && printk_ratelimit()) { 460 pr_warn("WARNING: nullifying cache flush/purge instruction\n"); 461 show_regs(regs); 462 } 463 if (insn & 0x20) { 464 /* Base modification */ 465 breg = (insn >> 21) & 0x1f; 466 xreg = (insn >> 16) & 0x1f; 467 if (breg && xreg) 468 regs->gr[breg] += regs->gr[xreg]; 469 } 470 regs->gr[0] |= PSW_N; 471 return 1; 472 473 case 0x180: 474 /* PROBE instruction */ 475 treg = insn & 0x1f; 476 if (regs->isr) { 477 tsk = current; 478 mm = tsk->mm; 479 if (mm) { 480 /* Search for VMA */ 481 address = regs->ior; 482 mmap_read_lock(mm); 483 vma = find_vma_prev(mm, address, &prev_vma); 484 mmap_read_unlock(mm); 485 486 /* 487 * Check if access to the VMA is okay. 488 * We don't allow for stack expansion. 489 */ 490 acc_type = (insn & 0x40) ? VM_WRITE : VM_READ; 491 if (vma 492 && address >= vma->vm_start 493 && (vma->vm_flags & acc_type) == acc_type) 494 val = 1; 495 } 496 } 497 if (treg) 498 regs->gr[treg] = val; 499 regs->gr[0] |= PSW_N; 500 return 1; 501 502 case 0x300: 503 /* LPA instruction */ 504 if (insn & 0x20) { 505 /* Base modification */ 506 breg = (insn >> 21) & 0x1f; 507 xreg = (insn >> 16) & 0x1f; 508 if (breg && xreg) 509 regs->gr[breg] += regs->gr[xreg]; 510 } 511 treg = insn & 0x1f; 512 if (treg) 513 regs->gr[treg] = 0; 514 regs->gr[0] |= PSW_N; 515 return 1; 516 517 default: 518 break; 519 } 520 521 return 0; 522 } 523