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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * S390 version
4 * Copyright IBM Corp. 1999
5 * Author(s): Hartmut Penner (hp@de.ibm.com)
6 * Ulrich Weigand (uweigand@de.ibm.com)
7 *
8 * Derived from "arch/i386/mm/fault.c"
9 * Copyright (C) 1995 Linus Torvalds
10 */
11
12#include <linux/kernel_stat.h>
13#include <linux/mmu_context.h>
14#include <linux/perf_event.h>
15#include <linux/signal.h>
16#include <linux/sched.h>
17#include <linux/sched/debug.h>
18#include <linux/jump_label.h>
19#include <linux/kernel.h>
20#include <linux/errno.h>
21#include <linux/string.h>
22#include <linux/types.h>
23#include <linux/ptrace.h>
24#include <linux/mman.h>
25#include <linux/mm.h>
26#include <linux/compat.h>
27#include <linux/smp.h>
28#include <linux/kdebug.h>
29#include <linux/init.h>
30#include <linux/console.h>
31#include <linux/extable.h>
32#include <linux/hardirq.h>
33#include <linux/kprobes.h>
34#include <linux/uaccess.h>
35#include <linux/hugetlb.h>
36#include <linux/kfence.h>
37#include <asm/asm-extable.h>
38#include <asm/asm-offsets.h>
39#include <asm/ptrace.h>
40#include <asm/fault.h>
41#include <asm/diag.h>
42#include <asm/gmap.h>
43#include <asm/irq.h>
44#include <asm/facility.h>
45#include <asm/uv.h>
46#include "../kernel/entry.h"
47
48enum fault_type {
49 KERNEL_FAULT,
50 USER_FAULT,
51 GMAP_FAULT,
52};
53
54static DEFINE_STATIC_KEY_FALSE(have_store_indication);
55
56static int __init fault_init(void)
57{
58 if (test_facility(75))
59 static_branch_enable(&have_store_indication);
60 return 0;
61}
62early_initcall(fault_init);
63
64/*
65 * Find out which address space caused the exception.
66 */
67static enum fault_type get_fault_type(struct pt_regs *regs)
68{
69 union teid teid = { .val = regs->int_parm_long };
70
71 if (likely(teid.as == PSW_BITS_AS_PRIMARY)) {
72 if (user_mode(regs))
73 return USER_FAULT;
74 if (!IS_ENABLED(CONFIG_PGSTE))
75 return KERNEL_FAULT;
76 if (test_pt_regs_flag(regs, PIF_GUEST_FAULT))
77 return GMAP_FAULT;
78 return KERNEL_FAULT;
79 }
80 if (teid.as == PSW_BITS_AS_SECONDARY)
81 return USER_FAULT;
82 /* Access register mode, not used in the kernel */
83 if (teid.as == PSW_BITS_AS_ACCREG)
84 return USER_FAULT;
85 /* Home space -> access via kernel ASCE */
86 return KERNEL_FAULT;
87}
88
89static unsigned long get_fault_address(struct pt_regs *regs)
90{
91 union teid teid = { .val = regs->int_parm_long };
92
93 return teid.addr * PAGE_SIZE;
94}
95
96static __always_inline bool fault_is_write(struct pt_regs *regs)
97{
98 union teid teid = { .val = regs->int_parm_long };
99
100 if (static_branch_likely(&have_store_indication))
101 return teid.fsi == TEID_FSI_STORE;
102 return false;
103}
104
105static void dump_pagetable(unsigned long asce, unsigned long address)
106{
107 unsigned long entry, *table = __va(asce & _ASCE_ORIGIN);
108
109 pr_alert("AS:%016lx ", asce);
110 switch (asce & _ASCE_TYPE_MASK) {
111 case _ASCE_TYPE_REGION1:
112 table += (address & _REGION1_INDEX) >> _REGION1_SHIFT;
113 if (get_kernel_nofault(entry, table))
114 goto bad;
115 pr_cont("R1:%016lx ", entry);
116 if (entry & _REGION_ENTRY_INVALID)
117 goto out;
118 table = __va(entry & _REGION_ENTRY_ORIGIN);
119 fallthrough;
120 case _ASCE_TYPE_REGION2:
121 table += (address & _REGION2_INDEX) >> _REGION2_SHIFT;
122 if (get_kernel_nofault(entry, table))
123 goto bad;
124 pr_cont("R2:%016lx ", entry);
125 if (entry & _REGION_ENTRY_INVALID)
126 goto out;
127 table = __va(entry & _REGION_ENTRY_ORIGIN);
128 fallthrough;
129 case _ASCE_TYPE_REGION3:
130 table += (address & _REGION3_INDEX) >> _REGION3_SHIFT;
131 if (get_kernel_nofault(entry, table))
132 goto bad;
133 pr_cont("R3:%016lx ", entry);
134 if (entry & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
135 goto out;
136 table = __va(entry & _REGION_ENTRY_ORIGIN);
137 fallthrough;
138 case _ASCE_TYPE_SEGMENT:
139 table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
140 if (get_kernel_nofault(entry, table))
141 goto bad;
142 pr_cont("S:%016lx ", entry);
143 if (entry & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
144 goto out;
145 table = __va(entry & _SEGMENT_ENTRY_ORIGIN);
146 }
147 table += (address & _PAGE_INDEX) >> _PAGE_SHIFT;
148 if (get_kernel_nofault(entry, table))
149 goto bad;
150 pr_cont("P:%016lx ", entry);
151out:
152 pr_cont("\n");
153 return;
154bad:
155 pr_cont("BAD\n");
156}
157
158static void dump_fault_info(struct pt_regs *regs)
159{
160 union teid teid = { .val = regs->int_parm_long };
161 unsigned long asce;
162
163 pr_alert("Failing address: %016lx TEID: %016lx\n",
164 get_fault_address(regs), teid.val);
165 pr_alert("Fault in ");
166 switch (teid.as) {
167 case PSW_BITS_AS_HOME:
168 pr_cont("home space ");
169 break;
170 case PSW_BITS_AS_SECONDARY:
171 pr_cont("secondary space ");
172 break;
173 case PSW_BITS_AS_ACCREG:
174 pr_cont("access register ");
175 break;
176 case PSW_BITS_AS_PRIMARY:
177 pr_cont("primary space ");
178 break;
179 }
180 pr_cont("mode while using ");
181 switch (get_fault_type(regs)) {
182 case USER_FAULT:
183 asce = S390_lowcore.user_asce.val;
184 pr_cont("user ");
185 break;
186 case GMAP_FAULT:
187 asce = ((struct gmap *)S390_lowcore.gmap)->asce;
188 pr_cont("gmap ");
189 break;
190 case KERNEL_FAULT:
191 asce = S390_lowcore.kernel_asce.val;
192 pr_cont("kernel ");
193 break;
194 default:
195 unreachable();
196 }
197 pr_cont("ASCE.\n");
198 dump_pagetable(asce, get_fault_address(regs));
199}
200
201int show_unhandled_signals = 1;
202
203void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault)
204{
205 static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST);
206
207 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
208 return;
209 if (!unhandled_signal(current, signr))
210 return;
211 if (!__ratelimit(&rs))
212 return;
213 pr_alert("User process fault: interruption code %04x ilc:%d ",
214 regs->int_code & 0xffff, regs->int_code >> 17);
215 print_vma_addr(KERN_CONT "in ", regs->psw.addr);
216 pr_cont("\n");
217 if (is_mm_fault)
218 dump_fault_info(regs);
219 show_regs(regs);
220}
221
222static void do_sigsegv(struct pt_regs *regs, int si_code)
223{
224 report_user_fault(regs, SIGSEGV, 1);
225 force_sig_fault(SIGSEGV, si_code, (void __user *)get_fault_address(regs));
226}
227
228static void handle_fault_error_nolock(struct pt_regs *regs, int si_code)
229{
230 enum fault_type fault_type;
231 unsigned long address;
232 bool is_write;
233
234 if (user_mode(regs)) {
235 if (WARN_ON_ONCE(!si_code))
236 si_code = SEGV_MAPERR;
237 return do_sigsegv(regs, si_code);
238 }
239 if (fixup_exception(regs))
240 return;
241 fault_type = get_fault_type(regs);
242 if (fault_type == KERNEL_FAULT) {
243 address = get_fault_address(regs);
244 is_write = fault_is_write(regs);
245 if (kfence_handle_page_fault(address, is_write, regs))
246 return;
247 }
248 if (fault_type == KERNEL_FAULT)
249 pr_alert("Unable to handle kernel pointer dereference in virtual kernel address space\n");
250 else
251 pr_alert("Unable to handle kernel paging request in virtual user address space\n");
252 dump_fault_info(regs);
253 die(regs, "Oops");
254}
255
256static void handle_fault_error(struct pt_regs *regs, int si_code)
257{
258 struct mm_struct *mm = current->mm;
259
260 mmap_read_unlock(mm);
261 handle_fault_error_nolock(regs, si_code);
262}
263
264static void do_sigbus(struct pt_regs *regs)
265{
266 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)get_fault_address(regs));
267}
268
269/*
270 * This routine handles page faults. It determines the address,
271 * and the problem, and then passes it off to one of the appropriate
272 * routines.
273 *
274 * interruption code (int_code):
275 * 04 Protection -> Write-Protection (suppression)
276 * 10 Segment translation -> Not present (nullification)
277 * 11 Page translation -> Not present (nullification)
278 * 3b Region third trans. -> Not present (nullification)
279 */
280static void do_exception(struct pt_regs *regs, int access)
281{
282 struct vm_area_struct *vma;
283 unsigned long address;
284 struct mm_struct *mm;
285 enum fault_type type;
286 unsigned int flags;
287 struct gmap *gmap;
288 vm_fault_t fault;
289 bool is_write;
290
291 /*
292 * The instruction that caused the program check has
293 * been nullified. Don't signal single step via SIGTRAP.
294 */
295 clear_thread_flag(TIF_PER_TRAP);
296 if (kprobe_page_fault(regs, 14))
297 return;
298 mm = current->mm;
299 address = get_fault_address(regs);
300 is_write = fault_is_write(regs);
301 type = get_fault_type(regs);
302 switch (type) {
303 case KERNEL_FAULT:
304 return handle_fault_error_nolock(regs, 0);
305 case USER_FAULT:
306 case GMAP_FAULT:
307 if (faulthandler_disabled() || !mm)
308 return handle_fault_error_nolock(regs, 0);
309 break;
310 }
311 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
312 flags = FAULT_FLAG_DEFAULT;
313 if (user_mode(regs))
314 flags |= FAULT_FLAG_USER;
315 if (is_write)
316 access = VM_WRITE;
317 if (access == VM_WRITE)
318 flags |= FAULT_FLAG_WRITE;
319 if (!(flags & FAULT_FLAG_USER))
320 goto lock_mmap;
321 vma = lock_vma_under_rcu(mm, address);
322 if (!vma)
323 goto lock_mmap;
324 if (!(vma->vm_flags & access)) {
325 vma_end_read(vma);
326 goto lock_mmap;
327 }
328 fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
329 if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED)))
330 vma_end_read(vma);
331 if (!(fault & VM_FAULT_RETRY)) {
332 count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
333 if (unlikely(fault & VM_FAULT_ERROR))
334 goto error;
335 return;
336 }
337 count_vm_vma_lock_event(VMA_LOCK_RETRY);
338 if (fault & VM_FAULT_MAJOR)
339 flags |= FAULT_FLAG_TRIED;
340
341 /* Quick path to respond to signals */
342 if (fault_signal_pending(fault, regs)) {
343 if (!user_mode(regs))
344 handle_fault_error_nolock(regs, 0);
345 return;
346 }
347lock_mmap:
348 mmap_read_lock(mm);
349 gmap = NULL;
350 if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) {
351 gmap = (struct gmap *)S390_lowcore.gmap;
352 current->thread.gmap_addr = address;
353 current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE);
354 current->thread.gmap_int_code = regs->int_code & 0xffff;
355 address = __gmap_translate(gmap, address);
356 if (address == -EFAULT)
357 return handle_fault_error(regs, SEGV_MAPERR);
358 if (gmap->pfault_enabled)
359 flags |= FAULT_FLAG_RETRY_NOWAIT;
360 }
361retry:
362 vma = find_vma(mm, address);
363 if (!vma)
364 return handle_fault_error(regs, SEGV_MAPERR);
365 if (unlikely(vma->vm_start > address)) {
366 if (!(vma->vm_flags & VM_GROWSDOWN))
367 return handle_fault_error(regs, SEGV_MAPERR);
368 vma = expand_stack(mm, address);
369 if (!vma)
370 return handle_fault_error_nolock(regs, SEGV_MAPERR);
371 }
372 if (unlikely(!(vma->vm_flags & access)))
373 return handle_fault_error(regs, SEGV_ACCERR);
374 fault = handle_mm_fault(vma, address, flags, regs);
375 if (fault_signal_pending(fault, regs)) {
376 if (flags & FAULT_FLAG_RETRY_NOWAIT)
377 mmap_read_unlock(mm);
378 if (!user_mode(regs))
379 handle_fault_error_nolock(regs, 0);
380 return;
381 }
382 /* The fault is fully completed (including releasing mmap lock) */
383 if (fault & VM_FAULT_COMPLETED) {
384 if (gmap) {
385 mmap_read_lock(mm);
386 goto gmap;
387 }
388 return;
389 }
390 if (unlikely(fault & VM_FAULT_ERROR)) {
391 mmap_read_unlock(mm);
392 goto error;
393 }
394 if (fault & VM_FAULT_RETRY) {
395 if (IS_ENABLED(CONFIG_PGSTE) && gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
396 /*
397 * FAULT_FLAG_RETRY_NOWAIT has been set,
398 * mmap_lock has not been released
399 */
400 current->thread.gmap_pfault = 1;
401 return handle_fault_error(regs, 0);
402 }
403 flags &= ~FAULT_FLAG_RETRY_NOWAIT;
404 flags |= FAULT_FLAG_TRIED;
405 mmap_read_lock(mm);
406 goto retry;
407 }
408gmap:
409 if (IS_ENABLED(CONFIG_PGSTE) && gmap) {
410 address = __gmap_link(gmap, current->thread.gmap_addr,
411 address);
412 if (address == -EFAULT)
413 return handle_fault_error(regs, SEGV_MAPERR);
414 if (address == -ENOMEM) {
415 fault = VM_FAULT_OOM;
416 mmap_read_unlock(mm);
417 goto error;
418 }
419 }
420 mmap_read_unlock(mm);
421 return;
422error:
423 if (fault & VM_FAULT_OOM) {
424 if (!user_mode(regs))
425 handle_fault_error_nolock(regs, 0);
426 else
427 pagefault_out_of_memory();
428 } else if (fault & VM_FAULT_SIGSEGV) {
429 if (!user_mode(regs))
430 handle_fault_error_nolock(regs, 0);
431 else
432 do_sigsegv(regs, SEGV_MAPERR);
433 } else if (fault & VM_FAULT_SIGBUS) {
434 if (!user_mode(regs))
435 handle_fault_error_nolock(regs, 0);
436 else
437 do_sigbus(regs);
438 } else {
439 BUG();
440 }
441}
442
443void do_protection_exception(struct pt_regs *regs)
444{
445 union teid teid = { .val = regs->int_parm_long };
446
447 /*
448 * Protection exceptions are suppressing, decrement psw address.
449 * The exception to this rule are aborted transactions, for these
450 * the PSW already points to the correct location.
451 */
452 if (!(regs->int_code & 0x200))
453 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
454 /*
455 * Check for low-address protection. This needs to be treated
456 * as a special case because the translation exception code
457 * field is not guaranteed to contain valid data in this case.
458 */
459 if (unlikely(!teid.b61)) {
460 if (user_mode(regs)) {
461 /* Low-address protection in user mode: cannot happen */
462 die(regs, "Low-address protection");
463 }
464 /*
465 * Low-address protection in kernel mode means
466 * NULL pointer write access in kernel mode.
467 */
468 return handle_fault_error_nolock(regs, 0);
469 }
470 if (unlikely(MACHINE_HAS_NX && teid.b56)) {
471 regs->int_parm_long = (teid.addr * PAGE_SIZE) | (regs->psw.addr & PAGE_MASK);
472 return handle_fault_error_nolock(regs, SEGV_ACCERR);
473 }
474 do_exception(regs, VM_WRITE);
475}
476NOKPROBE_SYMBOL(do_protection_exception);
477
478void do_dat_exception(struct pt_regs *regs)
479{
480 do_exception(regs, VM_ACCESS_FLAGS);
481}
482NOKPROBE_SYMBOL(do_dat_exception);
483
484#if IS_ENABLED(CONFIG_PGSTE)
485
486void do_secure_storage_access(struct pt_regs *regs)
487{
488 union teid teid = { .val = regs->int_parm_long };
489 unsigned long addr = get_fault_address(regs);
490 struct vm_area_struct *vma;
491 struct mm_struct *mm;
492 struct page *page;
493 struct gmap *gmap;
494 int rc;
495
496 /*
497 * Bit 61 indicates if the address is valid, if it is not the
498 * kernel should be stopped or SIGSEGV should be sent to the
499 * process. Bit 61 is not reliable without the misc UV feature,
500 * therefore this needs to be checked too.
501 */
502 if (uv_has_feature(BIT_UV_FEAT_MISC) && !teid.b61) {
503 /*
504 * When this happens, userspace did something that it
505 * was not supposed to do, e.g. branching into secure
506 * memory. Trigger a segmentation fault.
507 */
508 if (user_mode(regs)) {
509 send_sig(SIGSEGV, current, 0);
510 return;
511 }
512 /*
513 * The kernel should never run into this case and
514 * there is no way out of this situation.
515 */
516 panic("Unexpected PGM 0x3d with TEID bit 61=0");
517 }
518 switch (get_fault_type(regs)) {
519 case GMAP_FAULT:
520 mm = current->mm;
521 gmap = (struct gmap *)S390_lowcore.gmap;
522 mmap_read_lock(mm);
523 addr = __gmap_translate(gmap, addr);
524 mmap_read_unlock(mm);
525 if (IS_ERR_VALUE(addr))
526 return handle_fault_error_nolock(regs, SEGV_MAPERR);
527 fallthrough;
528 case USER_FAULT:
529 mm = current->mm;
530 mmap_read_lock(mm);
531 vma = find_vma(mm, addr);
532 if (!vma)
533 return handle_fault_error(regs, SEGV_MAPERR);
534 page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
535 if (IS_ERR_OR_NULL(page)) {
536 mmap_read_unlock(mm);
537 break;
538 }
539 if (arch_make_page_accessible(page))
540 send_sig(SIGSEGV, current, 0);
541 put_page(page);
542 mmap_read_unlock(mm);
543 break;
544 case KERNEL_FAULT:
545 page = phys_to_page(addr);
546 if (unlikely(!try_get_page(page)))
547 break;
548 rc = arch_make_page_accessible(page);
549 put_page(page);
550 if (rc)
551 BUG();
552 break;
553 default:
554 unreachable();
555 }
556}
557NOKPROBE_SYMBOL(do_secure_storage_access);
558
559void do_non_secure_storage_access(struct pt_regs *regs)
560{
561 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
562 unsigned long gaddr = get_fault_address(regs);
563
564 if (WARN_ON_ONCE(get_fault_type(regs) != GMAP_FAULT))
565 return handle_fault_error_nolock(regs, SEGV_MAPERR);
566 if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL)
567 send_sig(SIGSEGV, current, 0);
568}
569NOKPROBE_SYMBOL(do_non_secure_storage_access);
570
571void do_secure_storage_violation(struct pt_regs *regs)
572{
573 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
574 unsigned long gaddr = get_fault_address(regs);
575
576 /*
577 * If the VM has been rebooted, its address space might still contain
578 * secure pages from the previous boot.
579 * Clear the page so it can be reused.
580 */
581 if (!gmap_destroy_page(gmap, gaddr))
582 return;
583 /*
584 * Either KVM messed up the secure guest mapping or the same
585 * page is mapped into multiple secure guests.
586 *
587 * This exception is only triggered when a guest 2 is running
588 * and can therefore never occur in kernel context.
589 */
590 pr_warn_ratelimited("Secure storage violation in task: %s, pid %d\n",
591 current->comm, current->pid);
592 send_sig(SIGSEGV, current, 0);
593}
594
595#endif /* CONFIG_PGSTE */
1/*
2 * S390 version
3 * Copyright IBM Corp. 1999
4 * Author(s): Hartmut Penner (hp@de.ibm.com)
5 * Ulrich Weigand (uweigand@de.ibm.com)
6 *
7 * Derived from "arch/i386/mm/fault.c"
8 * Copyright (C) 1995 Linus Torvalds
9 */
10
11#include <linux/kernel_stat.h>
12#include <linux/perf_event.h>
13#include <linux/signal.h>
14#include <linux/sched.h>
15#include <linux/kernel.h>
16#include <linux/errno.h>
17#include <linux/string.h>
18#include <linux/types.h>
19#include <linux/ptrace.h>
20#include <linux/mman.h>
21#include <linux/mm.h>
22#include <linux/compat.h>
23#include <linux/smp.h>
24#include <linux/kdebug.h>
25#include <linux/init.h>
26#include <linux/console.h>
27#include <linux/module.h>
28#include <linux/hardirq.h>
29#include <linux/kprobes.h>
30#include <linux/uaccess.h>
31#include <linux/hugetlb.h>
32#include <asm/asm-offsets.h>
33#include <asm/pgtable.h>
34#include <asm/irq.h>
35#include <asm/mmu_context.h>
36#include <asm/facility.h>
37#include "../kernel/entry.h"
38
39#ifndef CONFIG_64BIT
40#define __FAIL_ADDR_MASK 0x7ffff000
41#define __SUBCODE_MASK 0x0200
42#define __PF_RES_FIELD 0ULL
43#else /* CONFIG_64BIT */
44#define __FAIL_ADDR_MASK -4096L
45#define __SUBCODE_MASK 0x0600
46#define __PF_RES_FIELD 0x8000000000000000ULL
47#endif /* CONFIG_64BIT */
48
49#define VM_FAULT_BADCONTEXT 0x010000
50#define VM_FAULT_BADMAP 0x020000
51#define VM_FAULT_BADACCESS 0x040000
52#define VM_FAULT_SIGNAL 0x080000
53#define VM_FAULT_PFAULT 0x100000
54
55static unsigned long store_indication __read_mostly;
56
57#ifdef CONFIG_64BIT
58static int __init fault_init(void)
59{
60 if (test_facility(75))
61 store_indication = 0xc00;
62 return 0;
63}
64early_initcall(fault_init);
65#endif
66
67static inline int notify_page_fault(struct pt_regs *regs)
68{
69 int ret = 0;
70
71 /* kprobe_running() needs smp_processor_id() */
72 if (kprobes_built_in() && !user_mode(regs)) {
73 preempt_disable();
74 if (kprobe_running() && kprobe_fault_handler(regs, 14))
75 ret = 1;
76 preempt_enable();
77 }
78 return ret;
79}
80
81
82/*
83 * Unlock any spinlocks which will prevent us from getting the
84 * message out.
85 */
86void bust_spinlocks(int yes)
87{
88 if (yes) {
89 oops_in_progress = 1;
90 } else {
91 int loglevel_save = console_loglevel;
92 console_unblank();
93 oops_in_progress = 0;
94 /*
95 * OK, the message is on the console. Now we call printk()
96 * without oops_in_progress set so that printk will give klogd
97 * a poke. Hold onto your hats...
98 */
99 console_loglevel = 15;
100 printk(" ");
101 console_loglevel = loglevel_save;
102 }
103}
104
105/*
106 * Returns the address space associated with the fault.
107 * Returns 0 for kernel space and 1 for user space.
108 */
109static inline int user_space_fault(struct pt_regs *regs)
110{
111 unsigned long trans_exc_code;
112
113 /*
114 * The lowest two bits of the translation exception
115 * identification indicate which paging table was used.
116 */
117 trans_exc_code = regs->int_parm_long & 3;
118 if (trans_exc_code == 3) /* home space -> kernel */
119 return 0;
120 if (user_mode(regs))
121 return 1;
122 if (trans_exc_code == 2) /* secondary space -> set_fs */
123 return current->thread.mm_segment.ar4;
124 if (current->flags & PF_VCPU)
125 return 1;
126 return 0;
127}
128
129static int bad_address(void *p)
130{
131 unsigned long dummy;
132
133 return probe_kernel_address((unsigned long *)p, dummy);
134}
135
136#ifdef CONFIG_64BIT
137static void dump_pagetable(unsigned long asce, unsigned long address)
138{
139 unsigned long *table = __va(asce & PAGE_MASK);
140
141 pr_alert("AS:%016lx ", asce);
142 switch (asce & _ASCE_TYPE_MASK) {
143 case _ASCE_TYPE_REGION1:
144 table = table + ((address >> 53) & 0x7ff);
145 if (bad_address(table))
146 goto bad;
147 pr_cont("R1:%016lx ", *table);
148 if (*table & _REGION_ENTRY_INVALID)
149 goto out;
150 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
151 /* fallthrough */
152 case _ASCE_TYPE_REGION2:
153 table = table + ((address >> 42) & 0x7ff);
154 if (bad_address(table))
155 goto bad;
156 pr_cont("R2:%016lx ", *table);
157 if (*table & _REGION_ENTRY_INVALID)
158 goto out;
159 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
160 /* fallthrough */
161 case _ASCE_TYPE_REGION3:
162 table = table + ((address >> 31) & 0x7ff);
163 if (bad_address(table))
164 goto bad;
165 pr_cont("R3:%016lx ", *table);
166 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
167 goto out;
168 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
169 /* fallthrough */
170 case _ASCE_TYPE_SEGMENT:
171 table = table + ((address >> 20) & 0x7ff);
172 if (bad_address(table))
173 goto bad;
174 pr_cont(KERN_CONT "S:%016lx ", *table);
175 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
176 goto out;
177 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
178 }
179 table = table + ((address >> 12) & 0xff);
180 if (bad_address(table))
181 goto bad;
182 pr_cont("P:%016lx ", *table);
183out:
184 pr_cont("\n");
185 return;
186bad:
187 pr_cont("BAD\n");
188}
189
190#else /* CONFIG_64BIT */
191
192static void dump_pagetable(unsigned long asce, unsigned long address)
193{
194 unsigned long *table = __va(asce & PAGE_MASK);
195
196 pr_alert("AS:%08lx ", asce);
197 table = table + ((address >> 20) & 0x7ff);
198 if (bad_address(table))
199 goto bad;
200 pr_cont("S:%08lx ", *table);
201 if (*table & _SEGMENT_ENTRY_INVALID)
202 goto out;
203 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
204 table = table + ((address >> 12) & 0xff);
205 if (bad_address(table))
206 goto bad;
207 pr_cont("P:%08lx ", *table);
208out:
209 pr_cont("\n");
210 return;
211bad:
212 pr_cont("BAD\n");
213}
214
215#endif /* CONFIG_64BIT */
216
217static void dump_fault_info(struct pt_regs *regs)
218{
219 unsigned long asce;
220
221 pr_alert("Fault in ");
222 switch (regs->int_parm_long & 3) {
223 case 3:
224 pr_cont("home space ");
225 break;
226 case 2:
227 pr_cont("secondary space ");
228 break;
229 case 1:
230 pr_cont("access register ");
231 break;
232 case 0:
233 pr_cont("primary space ");
234 break;
235 }
236 pr_cont("mode while using ");
237 if (!user_space_fault(regs)) {
238 asce = S390_lowcore.kernel_asce;
239 pr_cont("kernel ");
240 }
241#ifdef CONFIG_PGSTE
242 else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
243 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
244 asce = gmap->asce;
245 pr_cont("gmap ");
246 }
247#endif
248 else {
249 asce = S390_lowcore.user_asce;
250 pr_cont("user ");
251 }
252 pr_cont("ASCE.\n");
253 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
254}
255
256static inline void report_user_fault(struct pt_regs *regs, long signr)
257{
258 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
259 return;
260 if (!unhandled_signal(current, signr))
261 return;
262 if (!printk_ratelimit())
263 return;
264 printk(KERN_ALERT "User process fault: interruption code 0x%X ",
265 regs->int_code);
266 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
267 printk(KERN_CONT "\n");
268 printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
269 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
270 dump_fault_info(regs);
271 show_regs(regs);
272}
273
274/*
275 * Send SIGSEGV to task. This is an external routine
276 * to keep the stack usage of do_page_fault small.
277 */
278static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
279{
280 struct siginfo si;
281
282 report_user_fault(regs, SIGSEGV);
283 si.si_signo = SIGSEGV;
284 si.si_code = si_code;
285 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
286 force_sig_info(SIGSEGV, &si, current);
287}
288
289static noinline void do_no_context(struct pt_regs *regs)
290{
291 const struct exception_table_entry *fixup;
292 unsigned long address;
293
294 /* Are we prepared to handle this kernel fault? */
295 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
296 if (fixup) {
297 regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
298 return;
299 }
300
301 /*
302 * Oops. The kernel tried to access some bad page. We'll have to
303 * terminate things with extreme prejudice.
304 */
305 address = regs->int_parm_long & __FAIL_ADDR_MASK;
306 if (!user_space_fault(regs))
307 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
308 " in virtual kernel address space\n");
309 else
310 printk(KERN_ALERT "Unable to handle kernel paging request"
311 " in virtual user address space\n");
312 printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
313 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
314 dump_fault_info(regs);
315 die(regs, "Oops");
316 do_exit(SIGKILL);
317}
318
319static noinline void do_low_address(struct pt_regs *regs)
320{
321 /* Low-address protection hit in kernel mode means
322 NULL pointer write access in kernel mode. */
323 if (regs->psw.mask & PSW_MASK_PSTATE) {
324 /* Low-address protection hit in user mode 'cannot happen'. */
325 die (regs, "Low-address protection");
326 do_exit(SIGKILL);
327 }
328
329 do_no_context(regs);
330}
331
332static noinline void do_sigbus(struct pt_regs *regs)
333{
334 struct task_struct *tsk = current;
335 struct siginfo si;
336
337 /*
338 * Send a sigbus, regardless of whether we were in kernel
339 * or user mode.
340 */
341 si.si_signo = SIGBUS;
342 si.si_errno = 0;
343 si.si_code = BUS_ADRERR;
344 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
345 force_sig_info(SIGBUS, &si, tsk);
346}
347
348static noinline void do_fault_error(struct pt_regs *regs, int fault)
349{
350 int si_code;
351
352 switch (fault) {
353 case VM_FAULT_BADACCESS:
354 case VM_FAULT_BADMAP:
355 /* Bad memory access. Check if it is kernel or user space. */
356 if (user_mode(regs)) {
357 /* User mode accesses just cause a SIGSEGV */
358 si_code = (fault == VM_FAULT_BADMAP) ?
359 SEGV_MAPERR : SEGV_ACCERR;
360 do_sigsegv(regs, si_code);
361 return;
362 }
363 case VM_FAULT_BADCONTEXT:
364 case VM_FAULT_PFAULT:
365 do_no_context(regs);
366 break;
367 case VM_FAULT_SIGNAL:
368 if (!user_mode(regs))
369 do_no_context(regs);
370 break;
371 default: /* fault & VM_FAULT_ERROR */
372 if (fault & VM_FAULT_OOM) {
373 if (!user_mode(regs))
374 do_no_context(regs);
375 else
376 pagefault_out_of_memory();
377 } else if (fault & VM_FAULT_SIGBUS) {
378 /* Kernel mode? Handle exceptions or die */
379 if (!user_mode(regs))
380 do_no_context(regs);
381 else
382 do_sigbus(regs);
383 } else
384 BUG();
385 break;
386 }
387}
388
389/*
390 * This routine handles page faults. It determines the address,
391 * and the problem, and then passes it off to one of the appropriate
392 * routines.
393 *
394 * interruption code (int_code):
395 * 04 Protection -> Write-Protection (suprression)
396 * 10 Segment translation -> Not present (nullification)
397 * 11 Page translation -> Not present (nullification)
398 * 3b Region third trans. -> Not present (nullification)
399 */
400static inline int do_exception(struct pt_regs *regs, int access)
401{
402#ifdef CONFIG_PGSTE
403 struct gmap *gmap;
404#endif
405 struct task_struct *tsk;
406 struct mm_struct *mm;
407 struct vm_area_struct *vma;
408 unsigned long trans_exc_code;
409 unsigned long address;
410 unsigned int flags;
411 int fault;
412
413 tsk = current;
414 /*
415 * The instruction that caused the program check has
416 * been nullified. Don't signal single step via SIGTRAP.
417 */
418 clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
419
420 if (notify_page_fault(regs))
421 return 0;
422
423 mm = tsk->mm;
424 trans_exc_code = regs->int_parm_long;
425
426 /*
427 * Verify that the fault happened in user space, that
428 * we are not in an interrupt and that there is a
429 * user context.
430 */
431 fault = VM_FAULT_BADCONTEXT;
432 if (unlikely(!user_space_fault(regs) || in_atomic() || !mm))
433 goto out;
434
435 address = trans_exc_code & __FAIL_ADDR_MASK;
436 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
437 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
438 if (user_mode(regs))
439 flags |= FAULT_FLAG_USER;
440 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
441 flags |= FAULT_FLAG_WRITE;
442 down_read(&mm->mmap_sem);
443
444#ifdef CONFIG_PGSTE
445 gmap = (struct gmap *)
446 ((current->flags & PF_VCPU) ? S390_lowcore.gmap : 0);
447 if (gmap) {
448 address = __gmap_fault(address, gmap);
449 if (address == -EFAULT) {
450 fault = VM_FAULT_BADMAP;
451 goto out_up;
452 }
453 if (address == -ENOMEM) {
454 fault = VM_FAULT_OOM;
455 goto out_up;
456 }
457 if (gmap->pfault_enabled)
458 flags |= FAULT_FLAG_RETRY_NOWAIT;
459 }
460#endif
461
462retry:
463 fault = VM_FAULT_BADMAP;
464 vma = find_vma(mm, address);
465 if (!vma)
466 goto out_up;
467
468 if (unlikely(vma->vm_start > address)) {
469 if (!(vma->vm_flags & VM_GROWSDOWN))
470 goto out_up;
471 if (expand_stack(vma, address))
472 goto out_up;
473 }
474
475 /*
476 * Ok, we have a good vm_area for this memory access, so
477 * we can handle it..
478 */
479 fault = VM_FAULT_BADACCESS;
480 if (unlikely(!(vma->vm_flags & access)))
481 goto out_up;
482
483 if (is_vm_hugetlb_page(vma))
484 address &= HPAGE_MASK;
485 /*
486 * If for any reason at all we couldn't handle the fault,
487 * make sure we exit gracefully rather than endlessly redo
488 * the fault.
489 */
490 fault = handle_mm_fault(mm, vma, address, flags);
491 /* No reason to continue if interrupted by SIGKILL. */
492 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
493 fault = VM_FAULT_SIGNAL;
494 goto out;
495 }
496 if (unlikely(fault & VM_FAULT_ERROR))
497 goto out_up;
498
499 /*
500 * Major/minor page fault accounting is only done on the
501 * initial attempt. If we go through a retry, it is extremely
502 * likely that the page will be found in page cache at that point.
503 */
504 if (flags & FAULT_FLAG_ALLOW_RETRY) {
505 if (fault & VM_FAULT_MAJOR) {
506 tsk->maj_flt++;
507 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
508 regs, address);
509 } else {
510 tsk->min_flt++;
511 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
512 regs, address);
513 }
514 if (fault & VM_FAULT_RETRY) {
515#ifdef CONFIG_PGSTE
516 if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
517 /* FAULT_FLAG_RETRY_NOWAIT has been set,
518 * mmap_sem has not been released */
519 current->thread.gmap_pfault = 1;
520 fault = VM_FAULT_PFAULT;
521 goto out_up;
522 }
523#endif
524 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
525 * of starvation. */
526 flags &= ~(FAULT_FLAG_ALLOW_RETRY |
527 FAULT_FLAG_RETRY_NOWAIT);
528 flags |= FAULT_FLAG_TRIED;
529 down_read(&mm->mmap_sem);
530 goto retry;
531 }
532 }
533 fault = 0;
534out_up:
535 up_read(&mm->mmap_sem);
536out:
537 return fault;
538}
539
540void __kprobes do_protection_exception(struct pt_regs *regs)
541{
542 unsigned long trans_exc_code;
543 int fault;
544
545 trans_exc_code = regs->int_parm_long;
546 /*
547 * Protection exceptions are suppressing, decrement psw address.
548 * The exception to this rule are aborted transactions, for these
549 * the PSW already points to the correct location.
550 */
551 if (!(regs->int_code & 0x200))
552 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
553 /*
554 * Check for low-address protection. This needs to be treated
555 * as a special case because the translation exception code
556 * field is not guaranteed to contain valid data in this case.
557 */
558 if (unlikely(!(trans_exc_code & 4))) {
559 do_low_address(regs);
560 return;
561 }
562 fault = do_exception(regs, VM_WRITE);
563 if (unlikely(fault))
564 do_fault_error(regs, fault);
565}
566
567void __kprobes do_dat_exception(struct pt_regs *regs)
568{
569 int access, fault;
570
571 access = VM_READ | VM_EXEC | VM_WRITE;
572 fault = do_exception(regs, access);
573 if (unlikely(fault))
574 do_fault_error(regs, fault);
575}
576
577#ifdef CONFIG_PFAULT
578/*
579 * 'pfault' pseudo page faults routines.
580 */
581static int pfault_disable;
582
583static int __init nopfault(char *str)
584{
585 pfault_disable = 1;
586 return 1;
587}
588
589__setup("nopfault", nopfault);
590
591struct pfault_refbk {
592 u16 refdiagc;
593 u16 reffcode;
594 u16 refdwlen;
595 u16 refversn;
596 u64 refgaddr;
597 u64 refselmk;
598 u64 refcmpmk;
599 u64 reserved;
600} __attribute__ ((packed, aligned(8)));
601
602int pfault_init(void)
603{
604 struct pfault_refbk refbk = {
605 .refdiagc = 0x258,
606 .reffcode = 0,
607 .refdwlen = 5,
608 .refversn = 2,
609 .refgaddr = __LC_CURRENT_PID,
610 .refselmk = 1ULL << 48,
611 .refcmpmk = 1ULL << 48,
612 .reserved = __PF_RES_FIELD };
613 int rc;
614
615 if (pfault_disable)
616 return -1;
617 asm volatile(
618 " diag %1,%0,0x258\n"
619 "0: j 2f\n"
620 "1: la %0,8\n"
621 "2:\n"
622 EX_TABLE(0b,1b)
623 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
624 return rc;
625}
626
627void pfault_fini(void)
628{
629 struct pfault_refbk refbk = {
630 .refdiagc = 0x258,
631 .reffcode = 1,
632 .refdwlen = 5,
633 .refversn = 2,
634 };
635
636 if (pfault_disable)
637 return;
638 asm volatile(
639 " diag %0,0,0x258\n"
640 "0:\n"
641 EX_TABLE(0b,0b)
642 : : "a" (&refbk), "m" (refbk) : "cc");
643}
644
645static DEFINE_SPINLOCK(pfault_lock);
646static LIST_HEAD(pfault_list);
647
648static void pfault_interrupt(struct ext_code ext_code,
649 unsigned int param32, unsigned long param64)
650{
651 struct task_struct *tsk;
652 __u16 subcode;
653 pid_t pid;
654
655 /*
656 * Get the external interruption subcode & pfault
657 * initial/completion signal bit. VM stores this
658 * in the 'cpu address' field associated with the
659 * external interrupt.
660 */
661 subcode = ext_code.subcode;
662 if ((subcode & 0xff00) != __SUBCODE_MASK)
663 return;
664 inc_irq_stat(IRQEXT_PFL);
665 /* Get the token (= pid of the affected task). */
666 pid = sizeof(void *) == 4 ? param32 : param64;
667 rcu_read_lock();
668 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
669 if (tsk)
670 get_task_struct(tsk);
671 rcu_read_unlock();
672 if (!tsk)
673 return;
674 spin_lock(&pfault_lock);
675 if (subcode & 0x0080) {
676 /* signal bit is set -> a page has been swapped in by VM */
677 if (tsk->thread.pfault_wait == 1) {
678 /* Initial interrupt was faster than the completion
679 * interrupt. pfault_wait is valid. Set pfault_wait
680 * back to zero and wake up the process. This can
681 * safely be done because the task is still sleeping
682 * and can't produce new pfaults. */
683 tsk->thread.pfault_wait = 0;
684 list_del(&tsk->thread.list);
685 wake_up_process(tsk);
686 put_task_struct(tsk);
687 } else {
688 /* Completion interrupt was faster than initial
689 * interrupt. Set pfault_wait to -1 so the initial
690 * interrupt doesn't put the task to sleep.
691 * If the task is not running, ignore the completion
692 * interrupt since it must be a leftover of a PFAULT
693 * CANCEL operation which didn't remove all pending
694 * completion interrupts. */
695 if (tsk->state == TASK_RUNNING)
696 tsk->thread.pfault_wait = -1;
697 }
698 } else {
699 /* signal bit not set -> a real page is missing. */
700 if (WARN_ON_ONCE(tsk != current))
701 goto out;
702 if (tsk->thread.pfault_wait == 1) {
703 /* Already on the list with a reference: put to sleep */
704 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
705 set_tsk_need_resched(tsk);
706 } else if (tsk->thread.pfault_wait == -1) {
707 /* Completion interrupt was faster than the initial
708 * interrupt (pfault_wait == -1). Set pfault_wait
709 * back to zero and exit. */
710 tsk->thread.pfault_wait = 0;
711 } else {
712 /* Initial interrupt arrived before completion
713 * interrupt. Let the task sleep.
714 * An extra task reference is needed since a different
715 * cpu may set the task state to TASK_RUNNING again
716 * before the scheduler is reached. */
717 get_task_struct(tsk);
718 tsk->thread.pfault_wait = 1;
719 list_add(&tsk->thread.list, &pfault_list);
720 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
721 set_tsk_need_resched(tsk);
722 }
723 }
724out:
725 spin_unlock(&pfault_lock);
726 put_task_struct(tsk);
727}
728
729static int pfault_cpu_notify(struct notifier_block *self, unsigned long action,
730 void *hcpu)
731{
732 struct thread_struct *thread, *next;
733 struct task_struct *tsk;
734
735 switch (action & ~CPU_TASKS_FROZEN) {
736 case CPU_DEAD:
737 spin_lock_irq(&pfault_lock);
738 list_for_each_entry_safe(thread, next, &pfault_list, list) {
739 thread->pfault_wait = 0;
740 list_del(&thread->list);
741 tsk = container_of(thread, struct task_struct, thread);
742 wake_up_process(tsk);
743 put_task_struct(tsk);
744 }
745 spin_unlock_irq(&pfault_lock);
746 break;
747 default:
748 break;
749 }
750 return NOTIFY_OK;
751}
752
753static int __init pfault_irq_init(void)
754{
755 int rc;
756
757 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
758 if (rc)
759 goto out_extint;
760 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
761 if (rc)
762 goto out_pfault;
763 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
764 hotcpu_notifier(pfault_cpu_notify, 0);
765 return 0;
766
767out_pfault:
768 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
769out_extint:
770 pfault_disable = 1;
771 return rc;
772}
773early_initcall(pfault_irq_init);
774
775#endif /* CONFIG_PFAULT */