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