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 22 #include <asm/traps.h> 23 24 /* Various important other fields */ 25 #define bit22set(x) (x & 0x00000200) 26 #define bits23_25set(x) (x & 0x000001c0) 27 #define isGraphicsFlushRead(x) ((x & 0xfc003fdf) == 0x04001a80) 28 /* extended opcode is 0x6a */ 29 30 #define BITSSET 0x1c0 /* for identifying LDCW */ 31 32 33 int show_unhandled_signals = 1; 34 35 /* 36 * parisc_acctyp(unsigned int inst) -- 37 * Given a PA-RISC memory access instruction, determine if the 38 * the instruction would perform a memory read or memory write 39 * operation. 40 * 41 * This function assumes that the given instruction is a memory access 42 * instruction (i.e. you should really only call it if you know that 43 * the instruction has generated some sort of a memory access fault). 44 * 45 * Returns: 46 * VM_READ if read operation 47 * VM_WRITE if write operation 48 * VM_EXEC if execute operation 49 */ 50 static unsigned long 51 parisc_acctyp(unsigned long code, unsigned int inst) 52 { 53 if (code == 6 || code == 16) 54 return VM_EXEC; 55 56 switch (inst & 0xf0000000) { 57 case 0x40000000: /* load */ 58 case 0x50000000: /* new load */ 59 return VM_READ; 60 61 case 0x60000000: /* store */ 62 case 0x70000000: /* new store */ 63 return VM_WRITE; 64 65 case 0x20000000: /* coproc */ 66 case 0x30000000: /* coproc2 */ 67 if (bit22set(inst)) 68 return VM_WRITE; 69 /* fall through */ 70 71 case 0x0: /* indexed/memory management */ 72 if (bit22set(inst)) { 73 /* 74 * Check for the 'Graphics Flush Read' instruction. 75 * It resembles an FDC instruction, except for bits 76 * 20 and 21. Any combination other than zero will 77 * utilize the block mover functionality on some 78 * older PA-RISC platforms. The case where a block 79 * move is performed from VM to graphics IO space 80 * should be treated as a READ. 81 * 82 * The significance of bits 20,21 in the FDC 83 * instruction is: 84 * 85 * 00 Flush data cache (normal instruction behavior) 86 * 01 Graphics flush write (IO space -> VM) 87 * 10 Graphics flush read (VM -> IO space) 88 * 11 Graphics flush read/write (VM <-> IO space) 89 */ 90 if (isGraphicsFlushRead(inst)) 91 return VM_READ; 92 return VM_WRITE; 93 } else { 94 /* 95 * Check for LDCWX and LDCWS (semaphore instructions). 96 * If bits 23 through 25 are all 1's it is one of 97 * the above two instructions and is a write. 98 * 99 * Note: With the limited bits we are looking at, 100 * this will also catch PROBEW and PROBEWI. However, 101 * these should never get in here because they don't 102 * generate exceptions of the type: 103 * Data TLB miss fault/data page fault 104 * Data memory protection trap 105 */ 106 if (bits23_25set(inst) == BITSSET) 107 return VM_WRITE; 108 } 109 return VM_READ; /* Default */ 110 } 111 return VM_READ; /* Default */ 112 } 113 114 #undef bit22set 115 #undef bits23_25set 116 #undef isGraphicsFlushRead 117 #undef BITSSET 118 119 120 #if 0 121 /* This is the treewalk to find a vma which is the highest that has 122 * a start < addr. We're using find_vma_prev instead right now, but 123 * we might want to use this at some point in the future. Probably 124 * not, but I want it committed to CVS so I don't lose it :-) 125 */ 126 while (tree != vm_avl_empty) { 127 if (tree->vm_start > addr) { 128 tree = tree->vm_avl_left; 129 } else { 130 prev = tree; 131 if (prev->vm_next == NULL) 132 break; 133 if (prev->vm_next->vm_start > addr) 134 break; 135 tree = tree->vm_avl_right; 136 } 137 } 138 #endif 139 140 int fixup_exception(struct pt_regs *regs) 141 { 142 const struct exception_table_entry *fix; 143 144 fix = search_exception_tables(regs->iaoq[0]); 145 if (fix) { 146 /* 147 * Fix up get_user() and put_user(). 148 * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() sets the least-significant 149 * bit in the relative address of the fixup routine to indicate 150 * that %r8 should be loaded with -EFAULT to report a userspace 151 * access error. 152 */ 153 if (fix->fixup & 1) { 154 regs->gr[8] = -EFAULT; 155 156 /* zero target register for get_user() */ 157 if (parisc_acctyp(0, regs->iir) == VM_READ) { 158 int treg = regs->iir & 0x1f; 159 BUG_ON(treg == 0); 160 regs->gr[treg] = 0; 161 } 162 } 163 164 regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup; 165 regs->iaoq[0] &= ~3; 166 /* 167 * NOTE: In some cases the faulting instruction 168 * may be in the delay slot of a branch. We 169 * don't want to take the branch, so we don't 170 * increment iaoq[1], instead we set it to be 171 * iaoq[0]+4, and clear the B bit in the PSW 172 */ 173 regs->iaoq[1] = regs->iaoq[0] + 4; 174 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */ 175 176 return 1; 177 } 178 179 return 0; 180 } 181 182 /* 183 * parisc hardware trap list 184 * 185 * Documented in section 3 "Addressing and Access Control" of the 186 * "PA-RISC 1.1 Architecture and Instruction Set Reference Manual" 187 * https://parisc.wiki.kernel.org/index.php/File:Pa11_acd.pdf 188 * 189 * For implementation see handle_interruption() in traps.c 190 */ 191 static const char * const trap_description[] = { 192 [1] "High-priority machine check (HPMC)", 193 [2] "Power failure interrupt", 194 [3] "Recovery counter trap", 195 [5] "Low-priority machine check", 196 [6] "Instruction TLB miss fault", 197 [7] "Instruction access rights / protection trap", 198 [8] "Illegal instruction trap", 199 [9] "Break instruction trap", 200 [10] "Privileged operation trap", 201 [11] "Privileged register trap", 202 [12] "Overflow trap", 203 [13] "Conditional trap", 204 [14] "FP Assist Exception trap", 205 [15] "Data TLB miss fault", 206 [16] "Non-access ITLB miss fault", 207 [17] "Non-access DTLB miss fault", 208 [18] "Data memory protection/unaligned access trap", 209 [19] "Data memory break trap", 210 [20] "TLB dirty bit trap", 211 [21] "Page reference trap", 212 [22] "Assist emulation trap", 213 [25] "Taken branch trap", 214 [26] "Data memory access rights trap", 215 [27] "Data memory protection ID trap", 216 [28] "Unaligned data reference trap", 217 }; 218 219 const char *trap_name(unsigned long code) 220 { 221 const char *t = NULL; 222 223 if (code < ARRAY_SIZE(trap_description)) 224 t = trap_description[code]; 225 226 return t ? t : "Unknown trap"; 227 } 228 229 /* 230 * Print out info about fatal segfaults, if the show_unhandled_signals 231 * sysctl is set: 232 */ 233 static inline void 234 show_signal_msg(struct pt_regs *regs, unsigned long code, 235 unsigned long address, struct task_struct *tsk, 236 struct vm_area_struct *vma) 237 { 238 if (!unhandled_signal(tsk, SIGSEGV)) 239 return; 240 241 if (!printk_ratelimit()) 242 return; 243 244 pr_warn("\n"); 245 pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx", 246 tsk->comm, code, address); 247 print_vma_addr(KERN_CONT " in ", regs->iaoq[0]); 248 249 pr_cont("\ntrap #%lu: %s%c", code, trap_name(code), 250 vma ? ',':'\n'); 251 252 if (vma) 253 pr_cont(" vm_start = 0x%08lx, vm_end = 0x%08lx\n", 254 vma->vm_start, vma->vm_end); 255 256 show_regs(regs); 257 } 258 259 void do_page_fault(struct pt_regs *regs, unsigned long code, 260 unsigned long address) 261 { 262 struct vm_area_struct *vma, *prev_vma; 263 struct task_struct *tsk; 264 struct mm_struct *mm; 265 unsigned long acc_type; 266 vm_fault_t fault = 0; 267 unsigned int flags; 268 269 if (faulthandler_disabled()) 270 goto no_context; 271 272 tsk = current; 273 mm = tsk->mm; 274 if (!mm) 275 goto no_context; 276 277 flags = FAULT_FLAG_DEFAULT; 278 if (user_mode(regs)) 279 flags |= FAULT_FLAG_USER; 280 281 acc_type = parisc_acctyp(code, regs->iir); 282 if (acc_type & VM_WRITE) 283 flags |= FAULT_FLAG_WRITE; 284 retry: 285 mmap_read_lock(mm); 286 vma = find_vma_prev(mm, address, &prev_vma); 287 if (!vma || address < vma->vm_start) 288 goto check_expansion; 289 /* 290 * Ok, we have a good vm_area for this memory access. We still need to 291 * check the access permissions. 292 */ 293 294 good_area: 295 296 if ((vma->vm_flags & acc_type) != acc_type) 297 goto bad_area; 298 299 /* 300 * If for any reason at all we couldn't handle the fault, make 301 * sure we exit gracefully rather than endlessly redo the 302 * fault. 303 */ 304 305 fault = handle_mm_fault(vma, address, flags); 306 307 if (fault_signal_pending(fault, regs)) 308 return; 309 310 if (unlikely(fault & VM_FAULT_ERROR)) { 311 /* 312 * We hit a shared mapping outside of the file, or some 313 * other thing happened to us that made us unable to 314 * handle the page fault gracefully. 315 */ 316 if (fault & VM_FAULT_OOM) 317 goto out_of_memory; 318 else if (fault & VM_FAULT_SIGSEGV) 319 goto bad_area; 320 else if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON| 321 VM_FAULT_HWPOISON_LARGE)) 322 goto bad_area; 323 BUG(); 324 } 325 if (flags & FAULT_FLAG_ALLOW_RETRY) { 326 if (fault & VM_FAULT_MAJOR) 327 current->maj_flt++; 328 else 329 current->min_flt++; 330 if (fault & VM_FAULT_RETRY) { 331 /* 332 * No need to mmap_read_unlock(mm) as we would 333 * have already released it in __lock_page_or_retry 334 * in mm/filemap.c. 335 */ 336 flags |= FAULT_FLAG_TRIED; 337 goto retry; 338 } 339 } 340 mmap_read_unlock(mm); 341 return; 342 343 check_expansion: 344 vma = prev_vma; 345 if (vma && (expand_stack(vma, address) == 0)) 346 goto good_area; 347 348 /* 349 * Something tried to access memory that isn't in our memory map.. 350 */ 351 bad_area: 352 mmap_read_unlock(mm); 353 354 if (user_mode(regs)) { 355 int signo, si_code; 356 357 switch (code) { 358 case 15: /* Data TLB miss fault/Data page fault */ 359 /* send SIGSEGV when outside of vma */ 360 if (!vma || 361 address < vma->vm_start || address >= vma->vm_end) { 362 signo = SIGSEGV; 363 si_code = SEGV_MAPERR; 364 break; 365 } 366 367 /* send SIGSEGV for wrong permissions */ 368 if ((vma->vm_flags & acc_type) != acc_type) { 369 signo = SIGSEGV; 370 si_code = SEGV_ACCERR; 371 break; 372 } 373 374 /* probably address is outside of mapped file */ 375 /* fall through */ 376 case 17: /* NA data TLB miss / page fault */ 377 case 18: /* Unaligned access - PCXS only */ 378 signo = SIGBUS; 379 si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR; 380 break; 381 case 16: /* Non-access instruction TLB miss fault */ 382 case 26: /* PCXL: Data memory access rights trap */ 383 default: 384 signo = SIGSEGV; 385 si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR; 386 break; 387 } 388 #ifdef CONFIG_MEMORY_FAILURE 389 if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) { 390 unsigned int lsb = 0; 391 printk(KERN_ERR 392 "MCE: Killing %s:%d due to hardware memory corruption fault at %08lx\n", 393 tsk->comm, tsk->pid, address); 394 /* 395 * Either small page or large page may be poisoned. 396 * In other words, VM_FAULT_HWPOISON_LARGE and 397 * VM_FAULT_HWPOISON are mutually exclusive. 398 */ 399 if (fault & VM_FAULT_HWPOISON_LARGE) 400 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); 401 else if (fault & VM_FAULT_HWPOISON) 402 lsb = PAGE_SHIFT; 403 404 force_sig_mceerr(BUS_MCEERR_AR, (void __user *) address, 405 lsb); 406 return; 407 } 408 #endif 409 show_signal_msg(regs, code, address, tsk, vma); 410 411 force_sig_fault(signo, si_code, (void __user *) address); 412 return; 413 } 414 415 no_context: 416 417 if (!user_mode(regs) && fixup_exception(regs)) { 418 return; 419 } 420 421 parisc_terminate("Bad Address (null pointer deref?)", regs, code, address); 422 423 out_of_memory: 424 mmap_read_unlock(mm); 425 if (!user_mode(regs)) 426 goto no_context; 427 pagefault_out_of_memory(); 428 } 429