3 * Copyright IBM Corp. 1999
4 * Author(s): Hartmut Penner (hp@de.ibm.com)
5 * Ulrich Weigand (uweigand@de.ibm.com)
7 * Derived from "arch/i386/mm/fault.c"
8 * Copyright (C) 1995 Linus Torvalds
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>
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>
34 #include <asm/pgtable.h>
36 #include <asm/mmu_context.h>
37 #include <asm/facility.h>
38 #include "../kernel/entry.h"
40 #define __FAIL_ADDR_MASK -4096L
41 #define __SUBCODE_MASK 0x0600
42 #define __PF_RES_FIELD 0x8000000000000000ULL
44 #define VM_FAULT_BADCONTEXT 0x010000
45 #define VM_FAULT_BADMAP 0x020000
46 #define VM_FAULT_BADACCESS 0x040000
47 #define VM_FAULT_SIGNAL 0x080000
48 #define VM_FAULT_PFAULT 0x100000
50 static unsigned long store_indication __read_mostly
;
52 static int __init
fault_init(void)
54 if (test_facility(75))
55 store_indication
= 0xc00;
58 early_initcall(fault_init
);
60 static inline int notify_page_fault(struct pt_regs
*regs
)
64 /* kprobe_running() needs smp_processor_id() */
65 if (kprobes_built_in() && !user_mode(regs
)) {
67 if (kprobe_running() && kprobe_fault_handler(regs
, 14))
76 * Unlock any spinlocks which will prevent us from getting the
79 void bust_spinlocks(int yes
)
84 int loglevel_save
= console_loglevel
;
88 * OK, the message is on the console. Now we call printk()
89 * without oops_in_progress set so that printk will give klogd
90 * a poke. Hold onto your hats...
92 console_loglevel
= 15;
94 console_loglevel
= loglevel_save
;
99 * Returns the address space associated with the fault.
100 * Returns 0 for kernel space and 1 for user space.
102 static inline int user_space_fault(struct pt_regs
*regs
)
104 unsigned long trans_exc_code
;
107 * The lowest two bits of the translation exception
108 * identification indicate which paging table was used.
110 trans_exc_code
= regs
->int_parm_long
& 3;
111 if (trans_exc_code
== 3) /* home space -> kernel */
115 if (trans_exc_code
== 2) /* secondary space -> set_fs */
116 return current
->thread
.mm_segment
.ar4
;
117 if (current
->flags
& PF_VCPU
)
122 static int bad_address(void *p
)
126 return probe_kernel_address((unsigned long *)p
, dummy
);
129 static void dump_pagetable(unsigned long asce
, unsigned long address
)
131 unsigned long *table
= __va(asce
& PAGE_MASK
);
133 pr_alert("AS:%016lx ", asce
);
134 switch (asce
& _ASCE_TYPE_MASK
) {
135 case _ASCE_TYPE_REGION1
:
136 table
= table
+ ((address
>> 53) & 0x7ff);
137 if (bad_address(table
))
139 pr_cont("R1:%016lx ", *table
);
140 if (*table
& _REGION_ENTRY_INVALID
)
142 table
= (unsigned long *)(*table
& _REGION_ENTRY_ORIGIN
);
144 case _ASCE_TYPE_REGION2
:
145 table
= table
+ ((address
>> 42) & 0x7ff);
146 if (bad_address(table
))
148 pr_cont("R2:%016lx ", *table
);
149 if (*table
& _REGION_ENTRY_INVALID
)
151 table
= (unsigned long *)(*table
& _REGION_ENTRY_ORIGIN
);
153 case _ASCE_TYPE_REGION3
:
154 table
= table
+ ((address
>> 31) & 0x7ff);
155 if (bad_address(table
))
157 pr_cont("R3:%016lx ", *table
);
158 if (*table
& (_REGION_ENTRY_INVALID
| _REGION3_ENTRY_LARGE
))
160 table
= (unsigned long *)(*table
& _REGION_ENTRY_ORIGIN
);
162 case _ASCE_TYPE_SEGMENT
:
163 table
= table
+ ((address
>> 20) & 0x7ff);
164 if (bad_address(table
))
166 pr_cont("S:%016lx ", *table
);
167 if (*table
& (_SEGMENT_ENTRY_INVALID
| _SEGMENT_ENTRY_LARGE
))
169 table
= (unsigned long *)(*table
& _SEGMENT_ENTRY_ORIGIN
);
171 table
= table
+ ((address
>> 12) & 0xff);
172 if (bad_address(table
))
174 pr_cont("P:%016lx ", *table
);
182 static void dump_fault_info(struct pt_regs
*regs
)
186 pr_alert("Fault in ");
187 switch (regs
->int_parm_long
& 3) {
189 pr_cont("home space ");
192 pr_cont("secondary space ");
195 pr_cont("access register ");
198 pr_cont("primary space ");
201 pr_cont("mode while using ");
202 if (!user_space_fault(regs
)) {
203 asce
= S390_lowcore
.kernel_asce
;
207 else if ((current
->flags
& PF_VCPU
) && S390_lowcore
.gmap
) {
208 struct gmap
*gmap
= (struct gmap
*)S390_lowcore
.gmap
;
214 asce
= S390_lowcore
.user_asce
;
218 dump_pagetable(asce
, regs
->int_parm_long
& __FAIL_ADDR_MASK
);
221 static inline void report_user_fault(struct pt_regs
*regs
, long signr
)
223 if ((task_pid_nr(current
) > 1) && !show_unhandled_signals
)
225 if (!unhandled_signal(current
, signr
))
227 if (!printk_ratelimit())
229 printk(KERN_ALERT
"User process fault: interruption code %04x ilc:%d ",
230 regs
->int_code
& 0xffff, regs
->int_code
>> 17);
231 print_vma_addr(KERN_CONT
"in ", regs
->psw
.addr
);
232 printk(KERN_CONT
"\n");
233 printk(KERN_ALERT
"failing address: %016lx TEID: %016lx\n",
234 regs
->int_parm_long
& __FAIL_ADDR_MASK
, regs
->int_parm_long
);
235 dump_fault_info(regs
);
240 * Send SIGSEGV to task. This is an external routine
241 * to keep the stack usage of do_page_fault small.
243 static noinline
void do_sigsegv(struct pt_regs
*regs
, int si_code
)
247 report_user_fault(regs
, SIGSEGV
);
248 si
.si_signo
= SIGSEGV
;
249 si
.si_code
= si_code
;
250 si
.si_addr
= (void __user
*)(regs
->int_parm_long
& __FAIL_ADDR_MASK
);
251 force_sig_info(SIGSEGV
, &si
, current
);
254 static noinline
void do_no_context(struct pt_regs
*regs
)
256 const struct exception_table_entry
*fixup
;
258 /* Are we prepared to handle this kernel fault? */
259 fixup
= search_exception_tables(regs
->psw
.addr
);
261 regs
->psw
.addr
= extable_fixup(fixup
);
266 * Oops. The kernel tried to access some bad page. We'll have to
267 * terminate things with extreme prejudice.
269 if (!user_space_fault(regs
))
270 printk(KERN_ALERT
"Unable to handle kernel pointer dereference"
271 " in virtual kernel address space\n");
273 printk(KERN_ALERT
"Unable to handle kernel paging request"
274 " in virtual user address space\n");
275 printk(KERN_ALERT
"failing address: %016lx TEID: %016lx\n",
276 regs
->int_parm_long
& __FAIL_ADDR_MASK
, regs
->int_parm_long
);
277 dump_fault_info(regs
);
282 static noinline
void do_low_address(struct pt_regs
*regs
)
284 /* Low-address protection hit in kernel mode means
285 NULL pointer write access in kernel mode. */
286 if (regs
->psw
.mask
& PSW_MASK_PSTATE
) {
287 /* Low-address protection hit in user mode 'cannot happen'. */
288 die (regs
, "Low-address protection");
295 static noinline
void do_sigbus(struct pt_regs
*regs
)
297 struct task_struct
*tsk
= current
;
301 * Send a sigbus, regardless of whether we were in kernel
304 si
.si_signo
= SIGBUS
;
306 si
.si_code
= BUS_ADRERR
;
307 si
.si_addr
= (void __user
*)(regs
->int_parm_long
& __FAIL_ADDR_MASK
);
308 force_sig_info(SIGBUS
, &si
, tsk
);
311 static noinline
void do_fault_error(struct pt_regs
*regs
, int fault
)
316 case VM_FAULT_BADACCESS
:
317 case VM_FAULT_BADMAP
:
318 /* Bad memory access. Check if it is kernel or user space. */
319 if (user_mode(regs
)) {
320 /* User mode accesses just cause a SIGSEGV */
321 si_code
= (fault
== VM_FAULT_BADMAP
) ?
322 SEGV_MAPERR
: SEGV_ACCERR
;
323 do_sigsegv(regs
, si_code
);
326 case VM_FAULT_BADCONTEXT
:
327 case VM_FAULT_PFAULT
:
330 case VM_FAULT_SIGNAL
:
331 if (!user_mode(regs
))
334 default: /* fault & VM_FAULT_ERROR */
335 if (fault
& VM_FAULT_OOM
) {
336 if (!user_mode(regs
))
339 pagefault_out_of_memory();
340 } else if (fault
& VM_FAULT_SIGSEGV
) {
341 /* Kernel mode? Handle exceptions or die */
342 if (!user_mode(regs
))
345 do_sigsegv(regs
, SEGV_MAPERR
);
346 } else if (fault
& VM_FAULT_SIGBUS
) {
347 /* Kernel mode? Handle exceptions or die */
348 if (!user_mode(regs
))
359 * This routine handles page faults. It determines the address,
360 * and the problem, and then passes it off to one of the appropriate
363 * interruption code (int_code):
364 * 04 Protection -> Write-Protection (suprression)
365 * 10 Segment translation -> Not present (nullification)
366 * 11 Page translation -> Not present (nullification)
367 * 3b Region third trans. -> Not present (nullification)
369 static inline int do_exception(struct pt_regs
*regs
, int access
)
374 struct task_struct
*tsk
;
375 struct mm_struct
*mm
;
376 struct vm_area_struct
*vma
;
377 unsigned long trans_exc_code
;
378 unsigned long address
;
384 * The instruction that caused the program check has
385 * been nullified. Don't signal single step via SIGTRAP.
387 clear_pt_regs_flag(regs
, PIF_PER_TRAP
);
389 if (notify_page_fault(regs
))
393 trans_exc_code
= regs
->int_parm_long
;
396 * Verify that the fault happened in user space, that
397 * we are not in an interrupt and that there is a
400 fault
= VM_FAULT_BADCONTEXT
;
401 if (unlikely(!user_space_fault(regs
) || faulthandler_disabled() || !mm
))
404 address
= trans_exc_code
& __FAIL_ADDR_MASK
;
405 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS
, 1, regs
, address
);
406 flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
;
408 flags
|= FAULT_FLAG_USER
;
409 if (access
== VM_WRITE
|| (trans_exc_code
& store_indication
) == 0x400)
410 flags
|= FAULT_FLAG_WRITE
;
411 down_read(&mm
->mmap_sem
);
414 gmap
= (current
->flags
& PF_VCPU
) ?
415 (struct gmap
*) S390_lowcore
.gmap
: NULL
;
417 current
->thread
.gmap_addr
= address
;
418 address
= __gmap_translate(gmap
, address
);
419 if (address
== -EFAULT
) {
420 fault
= VM_FAULT_BADMAP
;
423 if (gmap
->pfault_enabled
)
424 flags
|= FAULT_FLAG_RETRY_NOWAIT
;
429 fault
= VM_FAULT_BADMAP
;
430 vma
= find_vma(mm
, address
);
434 if (unlikely(vma
->vm_start
> address
)) {
435 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
437 if (expand_stack(vma
, address
))
442 * Ok, we have a good vm_area for this memory access, so
445 fault
= VM_FAULT_BADACCESS
;
446 if (unlikely(!(vma
->vm_flags
& access
)))
449 if (is_vm_hugetlb_page(vma
))
450 address
&= HPAGE_MASK
;
452 * If for any reason at all we couldn't handle the fault,
453 * make sure we exit gracefully rather than endlessly redo
456 fault
= handle_mm_fault(mm
, vma
, address
, flags
);
457 /* No reason to continue if interrupted by SIGKILL. */
458 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
)) {
459 fault
= VM_FAULT_SIGNAL
;
462 if (unlikely(fault
& VM_FAULT_ERROR
))
466 * Major/minor page fault accounting is only done on the
467 * initial attempt. If we go through a retry, it is extremely
468 * likely that the page will be found in page cache at that point.
470 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
471 if (fault
& VM_FAULT_MAJOR
) {
473 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ
, 1,
477 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN
, 1,
480 if (fault
& VM_FAULT_RETRY
) {
482 if (gmap
&& (flags
& FAULT_FLAG_RETRY_NOWAIT
)) {
483 /* FAULT_FLAG_RETRY_NOWAIT has been set,
484 * mmap_sem has not been released */
485 current
->thread
.gmap_pfault
= 1;
486 fault
= VM_FAULT_PFAULT
;
490 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
492 flags
&= ~(FAULT_FLAG_ALLOW_RETRY
|
493 FAULT_FLAG_RETRY_NOWAIT
);
494 flags
|= FAULT_FLAG_TRIED
;
495 down_read(&mm
->mmap_sem
);
501 address
= __gmap_link(gmap
, current
->thread
.gmap_addr
,
503 if (address
== -EFAULT
) {
504 fault
= VM_FAULT_BADMAP
;
507 if (address
== -ENOMEM
) {
508 fault
= VM_FAULT_OOM
;
515 up_read(&mm
->mmap_sem
);
520 void do_protection_exception(struct pt_regs
*regs
)
522 unsigned long trans_exc_code
;
525 trans_exc_code
= regs
->int_parm_long
;
527 * Protection exceptions are suppressing, decrement psw address.
528 * The exception to this rule are aborted transactions, for these
529 * the PSW already points to the correct location.
531 if (!(regs
->int_code
& 0x200))
532 regs
->psw
.addr
= __rewind_psw(regs
->psw
, regs
->int_code
>> 16);
534 * Check for low-address protection. This needs to be treated
535 * as a special case because the translation exception code
536 * field is not guaranteed to contain valid data in this case.
538 if (unlikely(!(trans_exc_code
& 4))) {
539 do_low_address(regs
);
542 fault
= do_exception(regs
, VM_WRITE
);
544 do_fault_error(regs
, fault
);
546 NOKPROBE_SYMBOL(do_protection_exception
);
548 void do_dat_exception(struct pt_regs
*regs
)
552 access
= VM_READ
| VM_EXEC
| VM_WRITE
;
553 fault
= do_exception(regs
, access
);
555 do_fault_error(regs
, fault
);
557 NOKPROBE_SYMBOL(do_dat_exception
);
561 * 'pfault' pseudo page faults routines.
563 static int pfault_disable
;
565 static int __init
nopfault(char *str
)
571 __setup("nopfault", nopfault
);
573 struct pfault_refbk
{
582 } __attribute__ ((packed
, aligned(8)));
584 int pfault_init(void)
586 struct pfault_refbk refbk
= {
591 .refgaddr
= __LC_LPP
,
592 .refselmk
= 1ULL << 48,
593 .refcmpmk
= 1ULL << 48,
594 .reserved
= __PF_RES_FIELD
};
599 diag_stat_inc(DIAG_STAT_X258
);
601 " diag %1,%0,0x258\n"
606 : "=d" (rc
) : "a" (&refbk
), "m" (refbk
) : "cc");
610 void pfault_fini(void)
612 struct pfault_refbk refbk
= {
621 diag_stat_inc(DIAG_STAT_X258
);
626 : : "a" (&refbk
), "m" (refbk
) : "cc");
629 static DEFINE_SPINLOCK(pfault_lock
);
630 static LIST_HEAD(pfault_list
);
632 static void pfault_interrupt(struct ext_code ext_code
,
633 unsigned int param32
, unsigned long param64
)
635 struct task_struct
*tsk
;
640 * Get the external interruption subcode & pfault
641 * initial/completion signal bit. VM stores this
642 * in the 'cpu address' field associated with the
643 * external interrupt.
645 subcode
= ext_code
.subcode
;
646 if ((subcode
& 0xff00) != __SUBCODE_MASK
)
648 inc_irq_stat(IRQEXT_PFL
);
649 /* Get the token (= pid of the affected task). */
650 pid
= param64
& LPP_PFAULT_PID_MASK
;
652 tsk
= find_task_by_pid_ns(pid
, &init_pid_ns
);
654 get_task_struct(tsk
);
658 spin_lock(&pfault_lock
);
659 if (subcode
& 0x0080) {
660 /* signal bit is set -> a page has been swapped in by VM */
661 if (tsk
->thread
.pfault_wait
== 1) {
662 /* Initial interrupt was faster than the completion
663 * interrupt. pfault_wait is valid. Set pfault_wait
664 * back to zero and wake up the process. This can
665 * safely be done because the task is still sleeping
666 * and can't produce new pfaults. */
667 tsk
->thread
.pfault_wait
= 0;
668 list_del(&tsk
->thread
.list
);
669 wake_up_process(tsk
);
670 put_task_struct(tsk
);
672 /* Completion interrupt was faster than initial
673 * interrupt. Set pfault_wait to -1 so the initial
674 * interrupt doesn't put the task to sleep.
675 * If the task is not running, ignore the completion
676 * interrupt since it must be a leftover of a PFAULT
677 * CANCEL operation which didn't remove all pending
678 * completion interrupts. */
679 if (tsk
->state
== TASK_RUNNING
)
680 tsk
->thread
.pfault_wait
= -1;
683 /* signal bit not set -> a real page is missing. */
684 if (WARN_ON_ONCE(tsk
!= current
))
686 if (tsk
->thread
.pfault_wait
== 1) {
687 /* Already on the list with a reference: put to sleep */
688 __set_task_state(tsk
, TASK_UNINTERRUPTIBLE
);
689 set_tsk_need_resched(tsk
);
690 } else if (tsk
->thread
.pfault_wait
== -1) {
691 /* Completion interrupt was faster than the initial
692 * interrupt (pfault_wait == -1). Set pfault_wait
693 * back to zero and exit. */
694 tsk
->thread
.pfault_wait
= 0;
696 /* Initial interrupt arrived before completion
697 * interrupt. Let the task sleep.
698 * An extra task reference is needed since a different
699 * cpu may set the task state to TASK_RUNNING again
700 * before the scheduler is reached. */
701 get_task_struct(tsk
);
702 tsk
->thread
.pfault_wait
= 1;
703 list_add(&tsk
->thread
.list
, &pfault_list
);
704 __set_task_state(tsk
, TASK_UNINTERRUPTIBLE
);
705 set_tsk_need_resched(tsk
);
709 spin_unlock(&pfault_lock
);
710 put_task_struct(tsk
);
713 static int pfault_cpu_notify(struct notifier_block
*self
, unsigned long action
,
716 struct thread_struct
*thread
, *next
;
717 struct task_struct
*tsk
;
719 switch (action
& ~CPU_TASKS_FROZEN
) {
721 spin_lock_irq(&pfault_lock
);
722 list_for_each_entry_safe(thread
, next
, &pfault_list
, list
) {
723 thread
->pfault_wait
= 0;
724 list_del(&thread
->list
);
725 tsk
= container_of(thread
, struct task_struct
, thread
);
726 wake_up_process(tsk
);
727 put_task_struct(tsk
);
729 spin_unlock_irq(&pfault_lock
);
737 static int __init
pfault_irq_init(void)
741 rc
= register_external_irq(EXT_IRQ_CP_SERVICE
, pfault_interrupt
);
744 rc
= pfault_init() == 0 ? 0 : -EOPNOTSUPP
;
747 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL
);
748 hotcpu_notifier(pfault_cpu_notify
, 0);
752 unregister_external_irq(EXT_IRQ_CP_SERVICE
, pfault_interrupt
);
757 early_initcall(pfault_irq_init
);
759 #endif /* CONFIG_PFAULT */