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
parisc_acctyp(unsigned long code,unsigned int inst)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
fixup_exception(struct pt_regs * regs)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 the register encoded in the "or %r0,%r0,register"
154 * opcode should be loaded with -EFAULT to report a userspace
155 * access error.
156 */
157 if (fix->fixup & 1) {
158 int fault_error_reg = fix->err_opcode & 0x1f;
159 if (!WARN_ON(!fault_error_reg))
160 regs->gr[fault_error_reg] = -EFAULT;
161 pr_debug("Unalignment fixup of register %d at %pS\n",
162 fault_error_reg, (void*)regs->iaoq[0]);
163
164 /* zero target register for get_user() */
165 if (parisc_acctyp(0, regs->iir) == VM_READ) {
166 int treg = regs->iir & 0x1f;
167 BUG_ON(treg == 0);
168 regs->gr[treg] = 0;
169 }
170 }
171
172 regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup;
173 regs->iaoq[0] &= ~3;
174 /*
175 * NOTE: In some cases the faulting instruction
176 * may be in the delay slot of a branch. We
177 * don't want to take the branch, so we don't
178 * increment iaoq[1], instead we set it to be
179 * iaoq[0]+4, and clear the B bit in the PSW
180 */
181 regs->iaoq[1] = regs->iaoq[0] + 4;
182 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
183
184 return 1;
185 }
186
187 return 0;
188 }
189
190 /*
191 * parisc hardware trap list
192 *
193 * Documented in section 3 "Addressing and Access Control" of the
194 * "PA-RISC 1.1 Architecture and Instruction Set Reference Manual"
195 * https://parisc.wiki.kernel.org/index.php/File:Pa11_acd.pdf
196 *
197 * For implementation see handle_interruption() in traps.c
198 */
199 static const char * const trap_description[] = {
200 [1] = "High-priority machine check (HPMC)",
201 [2] = "Power failure interrupt",
202 [3] = "Recovery counter trap",
203 [5] = "Low-priority machine check",
204 [6] = "Instruction TLB miss fault",
205 [7] = "Instruction access rights / protection trap",
206 [8] = "Illegal instruction trap",
207 [9] = "Break instruction trap",
208 [10] = "Privileged operation trap",
209 [11] = "Privileged register trap",
210 [12] = "Overflow trap",
211 [13] = "Conditional trap",
212 [14] = "FP Assist Exception trap",
213 [15] = "Data TLB miss fault",
214 [16] = "Non-access ITLB miss fault",
215 [17] = "Non-access DTLB miss fault",
216 [18] = "Data memory protection/unaligned access trap",
217 [19] = "Data memory break trap",
218 [20] = "TLB dirty bit trap",
219 [21] = "Page reference trap",
220 [22] = "Assist emulation trap",
221 [25] = "Taken branch trap",
222 [26] = "Data memory access rights trap",
223 [27] = "Data memory protection ID trap",
224 [28] = "Unaligned data reference trap",
225 };
226
trap_name(unsigned long code)227 const char *trap_name(unsigned long code)
228 {
229 const char *t = NULL;
230
231 if (code < ARRAY_SIZE(trap_description))
232 t = trap_description[code];
233
234 return t ? t : "Unknown trap";
235 }
236
237 /*
238 * Print out info about fatal segfaults, if the show_unhandled_signals
239 * sysctl is set:
240 */
241 static inline void
show_signal_msg(struct pt_regs * regs,unsigned long code,unsigned long address,struct task_struct * tsk,struct vm_area_struct * vma)242 show_signal_msg(struct pt_regs *regs, unsigned long code,
243 unsigned long address, struct task_struct *tsk,
244 struct vm_area_struct *vma)
245 {
246 if (!unhandled_signal(tsk, SIGSEGV))
247 return;
248
249 if (!printk_ratelimit())
250 return;
251
252 pr_warn("\n");
253 pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx",
254 tsk->comm, code, address);
255 print_vma_addr(KERN_CONT " in ", regs->iaoq[0]);
256
257 pr_cont("\ntrap #%lu: %s%c", code, trap_name(code),
258 vma ? ',':'\n');
259
260 if (vma)
261 pr_cont(" vm_start = 0x%08lx, vm_end = 0x%08lx\n",
262 vma->vm_start, vma->vm_end);
263
264 show_regs(regs);
265 }
266
do_page_fault(struct pt_regs * regs,unsigned long code,unsigned long address)267 void do_page_fault(struct pt_regs *regs, unsigned long code,
268 unsigned long address)
269 {
270 struct vm_area_struct *vma, *prev_vma;
271 struct task_struct *tsk;
272 struct mm_struct *mm;
273 unsigned long acc_type;
274 vm_fault_t fault = 0;
275 unsigned int flags;
276 char *msg;
277
278 tsk = current;
279 mm = tsk->mm;
280 if (!mm) {
281 msg = "Page fault: no context";
282 goto no_context;
283 }
284
285 flags = FAULT_FLAG_DEFAULT;
286 if (user_mode(regs))
287 flags |= FAULT_FLAG_USER;
288
289 acc_type = parisc_acctyp(code, regs->iir);
290 if (acc_type & VM_WRITE)
291 flags |= FAULT_FLAG_WRITE;
292 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
293 retry:
294 mmap_read_lock(mm);
295 vma = find_vma_prev(mm, address, &prev_vma);
296 if (!vma || address < vma->vm_start) {
297 if (!prev_vma || !(prev_vma->vm_flags & VM_GROWSUP))
298 goto bad_area;
299 vma = expand_stack(mm, address);
300 if (!vma)
301 goto bad_area_nosemaphore;
302 }
303
304 /*
305 * Ok, we have a good vm_area for this memory access. We still need to
306 * check the access permissions.
307 */
308
309 if ((vma->vm_flags & acc_type) != acc_type)
310 goto bad_area;
311
312 /*
313 * If for any reason at all we couldn't handle the fault, make
314 * sure we exit gracefully rather than endlessly redo the
315 * fault.
316 */
317
318 fault = handle_mm_fault(vma, address, flags, regs);
319
320 if (fault_signal_pending(fault, regs)) {
321 if (!user_mode(regs)) {
322 msg = "Page fault: fault signal on kernel memory";
323 goto no_context;
324 }
325 return;
326 }
327
328 /* The fault is fully completed (including releasing mmap lock) */
329 if (fault & VM_FAULT_COMPLETED)
330 return;
331
332 if (unlikely(fault & VM_FAULT_ERROR)) {
333 /*
334 * We hit a shared mapping outside of the file, or some
335 * other thing happened to us that made us unable to
336 * handle the page fault gracefully.
337 */
338 if (fault & VM_FAULT_OOM)
339 goto out_of_memory;
340 else if (fault & VM_FAULT_SIGSEGV)
341 goto bad_area;
342 else if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
343 VM_FAULT_HWPOISON_LARGE))
344 goto bad_area;
345 BUG();
346 }
347 if (fault & VM_FAULT_RETRY) {
348 /*
349 * No need to mmap_read_unlock(mm) as we would
350 * have already released it in __lock_page_or_retry
351 * in mm/filemap.c.
352 */
353 flags |= FAULT_FLAG_TRIED;
354 goto retry;
355 }
356 mmap_read_unlock(mm);
357 return;
358
359 /*
360 * Something tried to access memory that isn't in our memory map..
361 */
362 bad_area:
363 mmap_read_unlock(mm);
364
365 bad_area_nosemaphore:
366 if (user_mode(regs)) {
367 int signo, si_code;
368
369 switch (code) {
370 case 15: /* Data TLB miss fault/Data page fault */
371 /* send SIGSEGV when outside of vma */
372 if (!vma ||
373 address < vma->vm_start || address >= vma->vm_end) {
374 signo = SIGSEGV;
375 si_code = SEGV_MAPERR;
376 break;
377 }
378
379 /* send SIGSEGV for wrong permissions */
380 if ((vma->vm_flags & acc_type) != acc_type) {
381 signo = SIGSEGV;
382 si_code = SEGV_ACCERR;
383 break;
384 }
385
386 /* probably address is outside of mapped file */
387 fallthrough;
388 case 17: /* NA data TLB miss / page fault */
389 case 18: /* Unaligned access - PCXS only */
390 signo = SIGBUS;
391 si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
392 break;
393 case 16: /* Non-access instruction TLB miss fault */
394 case 26: /* PCXL: Data memory access rights trap */
395 default:
396 signo = SIGSEGV;
397 si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
398 break;
399 }
400 #ifdef CONFIG_MEMORY_FAILURE
401 if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
402 unsigned int lsb = 0;
403 printk(KERN_ERR
404 "MCE: Killing %s:%d due to hardware memory corruption fault at %08lx\n",
405 tsk->comm, tsk->pid, address);
406 /*
407 * Either small page or large page may be poisoned.
408 * In other words, VM_FAULT_HWPOISON_LARGE and
409 * VM_FAULT_HWPOISON are mutually exclusive.
410 */
411 if (fault & VM_FAULT_HWPOISON_LARGE)
412 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
413 else if (fault & VM_FAULT_HWPOISON)
414 lsb = PAGE_SHIFT;
415
416 force_sig_mceerr(BUS_MCEERR_AR, (void __user *) address,
417 lsb);
418 return;
419 }
420 #endif
421 show_signal_msg(regs, code, address, tsk, vma);
422
423 force_sig_fault(signo, si_code, (void __user *) address);
424 return;
425 }
426 msg = "Page fault: bad address";
427
428 no_context:
429
430 if (!user_mode(regs) && fixup_exception(regs)) {
431 return;
432 }
433
434 parisc_terminate(msg, regs, code, address);
435
436 out_of_memory:
437 mmap_read_unlock(mm);
438 if (!user_mode(regs)) {
439 msg = "Page fault: out of memory";
440 goto no_context;
441 }
442 pagefault_out_of_memory();
443 }
444
445 /* Handle non-access data TLB miss faults.
446 *
447 * For probe instructions, accesses to userspace are considered allowed
448 * if they lie in a valid VMA and the access type matches. We are not
449 * allowed to handle MM faults here so there may be situations where an
450 * actual access would fail even though a probe was successful.
451 */
452 int
handle_nadtlb_fault(struct pt_regs * regs)453 handle_nadtlb_fault(struct pt_regs *regs)
454 {
455 unsigned long insn = regs->iir;
456 int breg, treg, xreg, val = 0;
457 struct vm_area_struct *vma;
458 struct task_struct *tsk;
459 struct mm_struct *mm;
460 unsigned long address;
461 unsigned long acc_type;
462
463 switch (insn & 0x380) {
464 case 0x280:
465 /* FDC instruction */
466 fallthrough;
467 case 0x380:
468 /* PDC and FIC instructions */
469 if (DEBUG_NATLB && printk_ratelimit()) {
470 pr_warn("WARNING: nullifying cache flush/purge instruction\n");
471 show_regs(regs);
472 }
473 if (insn & 0x20) {
474 /* Base modification */
475 breg = (insn >> 21) & 0x1f;
476 xreg = (insn >> 16) & 0x1f;
477 if (breg && xreg)
478 regs->gr[breg] += regs->gr[xreg];
479 }
480 regs->gr[0] |= PSW_N;
481 return 1;
482
483 case 0x180:
484 /* PROBE instruction */
485 treg = insn & 0x1f;
486 if (regs->isr) {
487 tsk = current;
488 mm = tsk->mm;
489 if (mm) {
490 /* Search for VMA */
491 address = regs->ior;
492 mmap_read_lock(mm);
493 vma = vma_lookup(mm, address);
494 mmap_read_unlock(mm);
495
496 /*
497 * Check if access to the VMA is okay.
498 * We don't allow for stack expansion.
499 */
500 acc_type = (insn & 0x40) ? VM_WRITE : VM_READ;
501 if (vma
502 && (vma->vm_flags & acc_type) == acc_type)
503 val = 1;
504 }
505 }
506 if (treg)
507 regs->gr[treg] = val;
508 regs->gr[0] |= PSW_N;
509 return 1;
510
511 case 0x300:
512 /* LPA instruction */
513 if (insn & 0x20) {
514 /* Base modification */
515 breg = (insn >> 21) & 0x1f;
516 xreg = (insn >> 16) & 0x1f;
517 if (breg && xreg)
518 regs->gr[breg] += regs->gr[xreg];
519 }
520 treg = insn & 0x1f;
521 if (treg)
522 regs->gr[treg] = 0;
523 regs->gr[0] |= PSW_N;
524 return 1;
525
526 default:
527 break;
528 }
529
530 return 0;
531 }
532