1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
4 *
5 * Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net)
6 * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz)
7 */
8
9 #include <asm/head.h>
10
11 #include <linux/string.h>
12 #include <linux/types.h>
13 #include <linux/sched.h>
14 #include <linux/sched/debug.h>
15 #include <linux/ptrace.h>
16 #include <linux/mman.h>
17 #include <linux/signal.h>
18 #include <linux/mm.h>
19 #include <linux/extable.h>
20 #include <linux/init.h>
21 #include <linux/perf_event.h>
22 #include <linux/interrupt.h>
23 #include <linux/kprobes.h>
24 #include <linux/kdebug.h>
25 #include <linux/percpu.h>
26 #include <linux/context_tracking.h>
27 #include <linux/uaccess.h>
28
29 #include <asm/page.h>
30 #include <asm/openprom.h>
31 #include <asm/oplib.h>
32 #include <asm/asi.h>
33 #include <asm/lsu.h>
34 #include <asm/sections.h>
35 #include <asm/mmu_context.h>
36 #include <asm/setup.h>
37
38 int show_unhandled_signals = 1;
39
40 static void __kprobes unhandled_fault(unsigned long address,
41 struct task_struct *tsk,
42 struct pt_regs *regs)
43 {
44 if ((unsigned long) address < PAGE_SIZE) {
45 printk(KERN_ALERT "Unable to handle kernel NULL "
46 "pointer dereference\n");
47 } else {
48 printk(KERN_ALERT "Unable to handle kernel paging request "
49 "at virtual address %016lx\n", (unsigned long)address);
50 }
51 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n",
52 (tsk->mm ?
53 CTX_HWBITS(tsk->mm->context) :
54 CTX_HWBITS(tsk->active_mm->context)));
55 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",
56 (tsk->mm ? (unsigned long) tsk->mm->pgd :
57 (unsigned long) tsk->active_mm->pgd));
58 die_if_kernel("Oops", regs);
59 }
60
61 static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr)
62 {
63 printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
64 regs->tpc);
65 printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]);
66 printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]);
67 printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr);
68 dump_stack();
69 unhandled_fault(regs->tpc, current, regs);
70 }
71
72 /*
73 * We now make sure that mmap_lock is held in all paths that call
74 * this. Additionally, to prevent kswapd from ripping ptes from
75 * under us, raise interrupts around the time that we look at the
76 * pte, kswapd will have to wait to get his smp ipi response from
77 * us. vmtruncate likewise. This saves us having to get pte lock.
78 */
79 static unsigned int get_user_insn(unsigned long tpc)
80 {
81 pgd_t *pgdp = pgd_offset(current->mm, tpc);
82 p4d_t *p4dp;
83 pud_t *pudp;
84 pmd_t *pmdp;
85 pte_t *ptep, pte;
86 unsigned long pa;
87 u32 insn = 0;
88
89 if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp)))
90 goto out;
91 p4dp = p4d_offset(pgdp, tpc);
92 if (p4d_none(*p4dp) || unlikely(p4d_bad(*p4dp)))
93 goto out;
94 pudp = pud_offset(p4dp, tpc);
95 if (pud_none(*pudp) || unlikely(pud_bad(*pudp)))
96 goto out;
97
98 /* This disables preemption for us as well. */
99 local_irq_disable();
100
101 pmdp = pmd_offset(pudp, tpc);
102 again:
103 if (pmd_none(*pmdp) || unlikely(pmd_bad(*pmdp)))
104 goto out_irq_enable;
105
106 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
107 if (is_hugetlb_pmd(*pmdp)) {
108 pa = pmd_pfn(*pmdp) << PAGE_SHIFT;
109 pa += tpc & ~HPAGE_MASK;
110
111 /* Use phys bypass so we don't pollute dtlb/dcache. */
112 __asm__ __volatile__("lduwa [%1] %2, %0"
113 : "=r" (insn)
114 : "r" (pa), "i" (ASI_PHYS_USE_EC));
115 } else
116 #endif
117 {
118 ptep = pte_offset_map(pmdp, tpc);
119 if (!ptep)
120 goto again;
121 pte = *ptep;
122 if (pte_present(pte)) {
123 pa = (pte_pfn(pte) << PAGE_SHIFT);
124 pa += (tpc & ~PAGE_MASK);
125
126 /* Use phys bypass so we don't pollute dtlb/dcache. */
127 __asm__ __volatile__("lduwa [%1] %2, %0"
128 : "=r" (insn)
129 : "r" (pa), "i" (ASI_PHYS_USE_EC));
130 }
131 pte_unmap(ptep);
132 }
133 out_irq_enable:
134 local_irq_enable();
135 out:
136 return insn;
137 }
138
139 static inline void
140 show_signal_msg(struct pt_regs *regs, int sig, int code,
141 unsigned long address, struct task_struct *tsk)
142 {
143 if (!unhandled_signal(tsk, sig))
144 return;
145
146 if (!printk_ratelimit())
147 return;
148
149 printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
150 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
151 tsk->comm, task_pid_nr(tsk), address,
152 (void *)regs->tpc, (void *)regs->u_regs[UREG_I7],
153 (void *)regs->u_regs[UREG_FP], code);
154
155 print_vma_addr(KERN_CONT " in ", regs->tpc);
156
157 printk(KERN_CONT "\n");
158 }
159
160 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
161 unsigned long fault_addr, unsigned int insn,
162 int fault_code)
163 {
164 unsigned long addr;
165
166 if (fault_code & FAULT_CODE_ITLB) {
167 addr = regs->tpc;
168 } else {
169 /* If we were able to probe the faulting instruction, use it
170 * to compute a precise fault address. Otherwise use the fault
171 * time provided address which may only have page granularity.
172 */
173 if (insn)
174 addr = compute_effective_address(regs, insn, 0);
175 else
176 addr = fault_addr;
177 }
178
179 if (unlikely(show_unhandled_signals))
180 show_signal_msg(regs, sig, code, addr, current);
181
182 force_sig_fault(sig, code, (void __user *) addr);
183 }
184
185 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
186 {
187 if (!insn) {
188 if (!regs->tpc || (regs->tpc & 0x3))
189 return 0;
190 if (regs->tstate & TSTATE_PRIV) {
191 insn = *(unsigned int *) regs->tpc;
192 } else {
193 insn = get_user_insn(regs->tpc);
194 }
195 }
196 return insn;
197 }
198
199 static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code,
200 int fault_code, unsigned int insn,
201 unsigned long address)
202 {
203 unsigned char asi = ASI_P;
204
205 if ((!insn) && (regs->tstate & TSTATE_PRIV))
206 goto cannot_handle;
207
208 /* If user insn could be read (thus insn is zero), that
209 * is fine. We will just gun down the process with a signal
210 * in that case.
211 */
212
213 if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) &&
214 (insn & 0xc0800000) == 0xc0800000) {
215 if (insn & 0x2000)
216 asi = (regs->tstate >> 24);
217 else
218 asi = (insn >> 5);
219 if ((asi & 0xf2) == 0x82) {
220 if (insn & 0x1000000) {
221 handle_ldf_stq(insn, regs);
222 } else {
223 /* This was a non-faulting load. Just clear the
224 * destination register(s) and continue with the next
225 * instruction. -jj
226 */
227 handle_ld_nf(insn, regs);
228 }
229 return;
230 }
231 }
232
233 /* Is this in ex_table? */
234 if (regs->tstate & TSTATE_PRIV) {
235 const struct exception_table_entry *entry;
236
237 entry = search_exception_tables(regs->tpc);
238 if (entry) {
239 regs->tpc = entry->fixup;
240 regs->tnpc = regs->tpc + 4;
241 return;
242 }
243 } else {
244 /* The si_code was set to make clear whether
245 * this was a SEGV_MAPERR or SEGV_ACCERR fault.
246 */
247 do_fault_siginfo(si_code, SIGSEGV, regs, address, insn, fault_code);
248 return;
249 }
250
251 cannot_handle:
252 unhandled_fault (address, current, regs);
253 }
254
255 static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs)
256 {
257 static int times;
258
259 if (times++ < 10)
260 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports "
261 "64-bit TPC [%lx]\n",
262 current->comm, current->pid,
263 regs->tpc);
264 show_regs(regs);
265 }
266
267 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
268 {
269 enum ctx_state prev_state = exception_enter();
270 struct mm_struct *mm = current->mm;
271 struct vm_area_struct *vma;
272 unsigned int insn = 0;
273 int si_code, fault_code;
274 vm_fault_t fault;
275 unsigned long address, mm_rss;
276 unsigned int flags = FAULT_FLAG_DEFAULT;
277
278 fault_code = get_thread_fault_code();
279
280 if (kprobe_page_fault(regs, 0))
281 goto exit_exception;
282
283 si_code = SEGV_MAPERR;
284 address = current_thread_info()->fault_address;
285
286 if ((fault_code & FAULT_CODE_ITLB) &&
287 (fault_code & FAULT_CODE_DTLB))
288 BUG();
289
290 if (test_thread_flag(TIF_32BIT)) {
291 if (!(regs->tstate & TSTATE_PRIV)) {
292 if (unlikely((regs->tpc >> 32) != 0)) {
293 bogus_32bit_fault_tpc(regs);
294 goto intr_or_no_mm;
295 }
296 }
297 if (unlikely((address >> 32) != 0))
298 goto intr_or_no_mm;
299 }
300
301 if (regs->tstate & TSTATE_PRIV) {
302 unsigned long tpc = regs->tpc;
303
304 /* Sanity check the PC. */
305 if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) ||
306 (tpc >= MODULES_VADDR && tpc < MODULES_END)) {
307 /* Valid, no problems... */
308 } else {
309 bad_kernel_pc(regs, address);
310 goto exit_exception;
311 }
312 } else
313 flags |= FAULT_FLAG_USER;
314
315 /*
316 * If we're in an interrupt or have no user
317 * context, we must not take the fault..
318 */
319 if (faulthandler_disabled() || !mm)
320 goto intr_or_no_mm;
321
322 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
323
324 if (!mmap_read_trylock(mm)) {
325 if ((regs->tstate & TSTATE_PRIV) &&
326 !search_exception_tables(regs->tpc)) {
327 insn = get_fault_insn(regs, insn);
328 goto handle_kernel_fault;
329 }
330
331 retry:
332 mmap_read_lock(mm);
333 }
334
335 if (fault_code & FAULT_CODE_BAD_RA)
336 goto do_sigbus;
337
338 vma = find_vma(mm, address);
339 if (!vma)
340 goto bad_area;
341
342 /* Pure DTLB misses do not tell us whether the fault causing
343 * load/store/atomic was a write or not, it only says that there
344 * was no match. So in such a case we (carefully) read the
345 * instruction to try and figure this out. It's an optimization
346 * so it's ok if we can't do this.
347 *
348 * Special hack, window spill/fill knows the exact fault type.
349 */
350 if (((fault_code &
351 (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) &&
352 (vma->vm_flags & VM_WRITE) != 0) {
353 insn = get_fault_insn(regs, 0);
354 if (!insn)
355 goto continue_fault;
356 /* All loads, stores and atomics have bits 30 and 31 both set
357 * in the instruction. Bit 21 is set in all stores, but we
358 * have to avoid prefetches which also have bit 21 set.
359 */
360 if ((insn & 0xc0200000) == 0xc0200000 &&
361 (insn & 0x01780000) != 0x01680000) {
362 /* Don't bother updating thread struct value,
363 * because update_mmu_cache only cares which tlb
364 * the access came from.
365 */
366 fault_code |= FAULT_CODE_WRITE;
367 }
368 }
369 continue_fault:
370
371 if (vma->vm_start <= address)
372 goto good_area;
373 if (!(vma->vm_flags & VM_GROWSDOWN))
374 goto bad_area;
375 if (!(fault_code & FAULT_CODE_WRITE)) {
376 /* Non-faulting loads shouldn't expand stack. */
377 insn = get_fault_insn(regs, insn);
378 if ((insn & 0xc0800000) == 0xc0800000) {
379 unsigned char asi;
380
381 if (insn & 0x2000)
382 asi = (regs->tstate >> 24);
383 else
384 asi = (insn >> 5);
385 if ((asi & 0xf2) == 0x82)
386 goto bad_area;
387 }
388 }
389 vma = expand_stack(mm, address);
390 if (!vma)
391 goto bad_area_nosemaphore;
392 /*
393 * Ok, we have a good vm_area for this memory access, so
394 * we can handle it..
395 */
396 good_area:
397 si_code = SEGV_ACCERR;
398
399 /* If we took a ITLB miss on a non-executable page, catch
400 * that here.
401 */
402 if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) {
403 WARN(address != regs->tpc,
404 "address (%lx) != regs->tpc (%lx)\n", address, regs->tpc);
405 WARN_ON(regs->tstate & TSTATE_PRIV);
406 goto bad_area;
407 }
408
409 if (fault_code & FAULT_CODE_WRITE) {
410 if (!(vma->vm_flags & VM_WRITE))
411 goto bad_area;
412
413 /* Spitfire has an icache which does not snoop
414 * processor stores. Later processors do...
415 */
416 if (tlb_type == spitfire &&
417 (vma->vm_flags & VM_EXEC) != 0 &&
418 vma->vm_file != NULL)
419 set_thread_fault_code(fault_code |
420 FAULT_CODE_BLKCOMMIT);
421
422 flags |= FAULT_FLAG_WRITE;
423 } else {
424 /* Allow reads even for write-only mappings */
425 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
426 goto bad_area;
427 }
428
429 fault = handle_mm_fault(vma, address, flags, regs);
430
431 if (fault_signal_pending(fault, regs)) {
432 if (regs->tstate & TSTATE_PRIV) {
433 insn = get_fault_insn(regs, insn);
434 goto handle_kernel_fault;
435 }
436 goto exit_exception;
437 }
438
439 /* The fault is fully completed (including releasing mmap lock) */
440 if (fault & VM_FAULT_COMPLETED)
441 goto lock_released;
442
443 if (unlikely(fault & VM_FAULT_ERROR)) {
444 if (fault & VM_FAULT_OOM)
445 goto out_of_memory;
446 else if (fault & VM_FAULT_SIGSEGV)
447 goto bad_area;
448 else if (fault & VM_FAULT_SIGBUS)
449 goto do_sigbus;
450 BUG();
451 }
452
453 if (fault & VM_FAULT_RETRY) {
454 flags |= FAULT_FLAG_TRIED;
455
456 /* No need to mmap_read_unlock(mm) as we would
457 * have already released it in __lock_page_or_retry
458 * in mm/filemap.c.
459 */
460
461 goto retry;
462 }
463 mmap_read_unlock(mm);
464
465 lock_released:
466 mm_rss = get_mm_rss(mm);
467 #if defined(CONFIG_TRANSPARENT_HUGEPAGE)
468 mm_rss -= (mm->context.thp_pte_count * (HPAGE_SIZE / PAGE_SIZE));
469 #endif
470 if (unlikely(mm_rss >
471 mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit))
472 tsb_grow(mm, MM_TSB_BASE, mm_rss);
473 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
474 mm_rss = mm->context.hugetlb_pte_count + mm->context.thp_pte_count;
475 mm_rss *= REAL_HPAGE_PER_HPAGE;
476 if (unlikely(mm_rss >
477 mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) {
478 if (mm->context.tsb_block[MM_TSB_HUGE].tsb)
479 tsb_grow(mm, MM_TSB_HUGE, mm_rss);
480 else
481 hugetlb_setup(regs);
482
483 }
484 #endif
485 exit_exception:
486 exception_exit(prev_state);
487 return;
488
489 /*
490 * Something tried to access memory that isn't in our memory map..
491 * Fix it, but check if it's kernel or user first..
492 */
493 bad_area:
494 mmap_read_unlock(mm);
495 bad_area_nosemaphore:
496 insn = get_fault_insn(regs, insn);
497
498 handle_kernel_fault:
499 do_kernel_fault(regs, si_code, fault_code, insn, address);
500 goto exit_exception;
501
502 /*
503 * We ran out of memory, or some other thing happened to us that made
504 * us unable to handle the page fault gracefully.
505 */
506 out_of_memory:
507 insn = get_fault_insn(regs, insn);
508 mmap_read_unlock(mm);
509 if (!(regs->tstate & TSTATE_PRIV)) {
510 pagefault_out_of_memory();
511 goto exit_exception;
512 }
513 goto handle_kernel_fault;
514
515 intr_or_no_mm:
516 insn = get_fault_insn(regs, 0);
517 goto handle_kernel_fault;
518
519 do_sigbus:
520 insn = get_fault_insn(regs, insn);
521 mmap_read_unlock(mm);
522
523 /*
524 * Send a sigbus, regardless of whether we were in kernel
525 * or user mode.
526 */
527 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, address, insn, fault_code);
528
529 /* Kernel mode? Handle exceptions or die */
530 if (regs->tstate & TSTATE_PRIV)
531 goto handle_kernel_fault;
532 }
533
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