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