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>
33 #include <asm/pgtable.h>
35 #include <asm/mmu_context.h>
36 #include <asm/facility.h>
37 #include "../kernel/entry.h"
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 */
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
55 static unsigned long store_indication __read_mostly;
58 static int __init fault_init(void)
60 if (test_facility(75))
61 store_indication = 0xc00;
64 early_initcall(fault_init);
67 static inline int notify_page_fault(struct pt_regs *regs)
71 /* kprobe_running() needs smp_processor_id() */
72 if (kprobes_built_in() && !user_mode(regs)) {
74 if (kprobe_running() && kprobe_fault_handler(regs, 14))
83 * Unlock any spinlocks which will prevent us from getting the
86 void bust_spinlocks(int yes)
91 int loglevel_save = console_loglevel;
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...
99 console_loglevel = 15;
101 console_loglevel = loglevel_save;
106 * Returns the address space associated with the fault.
107 * Returns 0 for kernel space and 1 for user space.
109 static inline int user_space_fault(unsigned long trans_exc_code)
112 * The lowest two bits of the translation exception
113 * identification indicate which paging table was used.
116 if (trans_exc_code == 2)
117 /* Access via secondary space, set_fs setting decides */
118 return current->thread.mm_segment.ar4;
120 * Access via primary space or access register is from user space
121 * and access via home space is from the kernel.
123 return trans_exc_code != 3;
126 static inline void report_user_fault(struct pt_regs *regs, long signr)
128 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
130 if (!unhandled_signal(current, signr))
132 if (!printk_ratelimit())
134 printk(KERN_ALERT "User process fault: interruption code 0x%X ",
136 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
137 printk(KERN_CONT "\n");
138 printk(KERN_ALERT "failing address: %lX\n",
139 regs->int_parm_long & __FAIL_ADDR_MASK);
144 * Send SIGSEGV to task. This is an external routine
145 * to keep the stack usage of do_page_fault small.
147 static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
151 report_user_fault(regs, SIGSEGV);
152 si.si_signo = SIGSEGV;
153 si.si_code = si_code;
154 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
155 force_sig_info(SIGSEGV, &si, current);
158 static noinline void do_no_context(struct pt_regs *regs)
160 const struct exception_table_entry *fixup;
161 unsigned long address;
163 /* Are we prepared to handle this kernel fault? */
164 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
166 regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
171 * Oops. The kernel tried to access some bad page. We'll have to
172 * terminate things with extreme prejudice.
174 address = regs->int_parm_long & __FAIL_ADDR_MASK;
175 if (!user_space_fault(regs->int_parm_long))
176 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
177 " at virtual kernel address %p\n", (void *)address);
179 printk(KERN_ALERT "Unable to handle kernel paging request"
180 " at virtual user address %p\n", (void *)address);
186 static noinline void do_low_address(struct pt_regs *regs)
188 /* Low-address protection hit in kernel mode means
189 NULL pointer write access in kernel mode. */
190 if (regs->psw.mask & PSW_MASK_PSTATE) {
191 /* Low-address protection hit in user mode 'cannot happen'. */
192 die (regs, "Low-address protection");
199 static noinline void do_sigbus(struct pt_regs *regs)
201 struct task_struct *tsk = current;
205 * Send a sigbus, regardless of whether we were in kernel
208 si.si_signo = SIGBUS;
210 si.si_code = BUS_ADRERR;
211 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
212 force_sig_info(SIGBUS, &si, tsk);
215 static noinline void do_fault_error(struct pt_regs *regs, int fault)
220 case VM_FAULT_BADACCESS:
221 case VM_FAULT_BADMAP:
222 /* Bad memory access. Check if it is kernel or user space. */
223 if (user_mode(regs)) {
224 /* User mode accesses just cause a SIGSEGV */
225 si_code = (fault == VM_FAULT_BADMAP) ?
226 SEGV_MAPERR : SEGV_ACCERR;
227 do_sigsegv(regs, si_code);
230 case VM_FAULT_BADCONTEXT:
231 case VM_FAULT_PFAULT:
234 case VM_FAULT_SIGNAL:
235 if (!user_mode(regs))
238 default: /* fault & VM_FAULT_ERROR */
239 if (fault & VM_FAULT_OOM) {
240 if (!user_mode(regs))
243 pagefault_out_of_memory();
244 } else if (fault & VM_FAULT_SIGBUS) {
245 /* Kernel mode? Handle exceptions or die */
246 if (!user_mode(regs))
257 * This routine handles page faults. It determines the address,
258 * and the problem, and then passes it off to one of the appropriate
261 * interruption code (int_code):
262 * 04 Protection -> Write-Protection (suprression)
263 * 10 Segment translation -> Not present (nullification)
264 * 11 Page translation -> Not present (nullification)
265 * 3b Region third trans. -> Not present (nullification)
267 static inline int do_exception(struct pt_regs *regs, int access)
272 struct task_struct *tsk;
273 struct mm_struct *mm;
274 struct vm_area_struct *vma;
275 unsigned long trans_exc_code;
276 unsigned long address;
282 * The instruction that caused the program check has
283 * been nullified. Don't signal single step via SIGTRAP.
285 clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
287 if (notify_page_fault(regs))
291 trans_exc_code = regs->int_parm_long;
294 * Verify that the fault happened in user space, that
295 * we are not in an interrupt and that there is a
298 fault = VM_FAULT_BADCONTEXT;
299 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
302 address = trans_exc_code & __FAIL_ADDR_MASK;
303 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
304 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
306 flags |= FAULT_FLAG_USER;
307 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
308 flags |= FAULT_FLAG_WRITE;
309 down_read(&mm->mmap_sem);
312 gmap = (struct gmap *)
313 ((current->flags & PF_VCPU) ? S390_lowcore.gmap : 0);
315 address = __gmap_fault(address, gmap);
316 if (address == -EFAULT) {
317 fault = VM_FAULT_BADMAP;
320 if (address == -ENOMEM) {
321 fault = VM_FAULT_OOM;
324 if (gmap->pfault_enabled)
325 flags |= FAULT_FLAG_RETRY_NOWAIT;
330 fault = VM_FAULT_BADMAP;
331 vma = find_vma(mm, address);
335 if (unlikely(vma->vm_start > address)) {
336 if (!(vma->vm_flags & VM_GROWSDOWN))
338 if (expand_stack(vma, address))
343 * Ok, we have a good vm_area for this memory access, so
346 fault = VM_FAULT_BADACCESS;
347 if (unlikely(!(vma->vm_flags & access)))
350 if (is_vm_hugetlb_page(vma))
351 address &= HPAGE_MASK;
353 * If for any reason at all we couldn't handle the fault,
354 * make sure we exit gracefully rather than endlessly redo
357 fault = handle_mm_fault(mm, vma, address, flags);
358 /* No reason to continue if interrupted by SIGKILL. */
359 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
360 fault = VM_FAULT_SIGNAL;
363 if (unlikely(fault & VM_FAULT_ERROR))
367 * Major/minor page fault accounting is only done on the
368 * initial attempt. If we go through a retry, it is extremely
369 * likely that the page will be found in page cache at that point.
371 if (flags & FAULT_FLAG_ALLOW_RETRY) {
372 if (fault & VM_FAULT_MAJOR) {
374 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
378 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
381 if (fault & VM_FAULT_RETRY) {
383 if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
384 /* FAULT_FLAG_RETRY_NOWAIT has been set,
385 * mmap_sem has not been released */
386 current->thread.gmap_pfault = 1;
387 fault = VM_FAULT_PFAULT;
391 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
393 flags &= ~(FAULT_FLAG_ALLOW_RETRY |
394 FAULT_FLAG_RETRY_NOWAIT);
395 flags |= FAULT_FLAG_TRIED;
396 down_read(&mm->mmap_sem);
402 up_read(&mm->mmap_sem);
407 void __kprobes do_protection_exception(struct pt_regs *regs)
409 unsigned long trans_exc_code;
412 trans_exc_code = regs->int_parm_long;
414 * Protection exceptions are suppressing, decrement psw address.
415 * The exception to this rule are aborted transactions, for these
416 * the PSW already points to the correct location.
418 if (!(regs->int_code & 0x200))
419 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
421 * Check for low-address protection. This needs to be treated
422 * as a special case because the translation exception code
423 * field is not guaranteed to contain valid data in this case.
425 if (unlikely(!(trans_exc_code & 4))) {
426 do_low_address(regs);
429 fault = do_exception(regs, VM_WRITE);
431 do_fault_error(regs, fault);
434 void __kprobes do_dat_exception(struct pt_regs *regs)
438 access = VM_READ | VM_EXEC | VM_WRITE;
439 fault = do_exception(regs, access);
441 do_fault_error(regs, fault);
444 int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
449 /* Emulate a uaccess fault from kernel mode. */
450 regs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT | PSW_MASK_MCHECK;
451 if (!irqs_disabled())
452 regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
453 regs.psw.addr = (unsigned long) __builtin_return_address(0);
454 regs.psw.addr |= PSW_ADDR_AMODE;
455 regs.int_code = pgm_int_code;
456 regs.int_parm_long = (uaddr & PAGE_MASK) | 2;
457 access = write ? VM_WRITE : VM_READ;
458 fault = do_exception(®s, access);
460 * Since the fault happened in kernel mode while performing a uaccess
461 * all we need to do now is emulating a fixup in case "fault" is not
463 * For the calling uaccess functions this results always in -EFAULT.
465 return fault ? -EFAULT : 0;
470 * 'pfault' pseudo page faults routines.
472 static int pfault_disable;
474 static int __init nopfault(char *str)
480 __setup("nopfault", nopfault);
482 struct pfault_refbk {
491 } __attribute__ ((packed, aligned(8)));
493 int pfault_init(void)
495 struct pfault_refbk refbk = {
500 .refgaddr = __LC_CURRENT_PID,
501 .refselmk = 1ULL << 48,
502 .refcmpmk = 1ULL << 48,
503 .reserved = __PF_RES_FIELD };
509 " diag %1,%0,0x258\n"
514 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
518 void pfault_fini(void)
520 struct pfault_refbk refbk = {
533 : : "a" (&refbk), "m" (refbk) : "cc");
536 static DEFINE_SPINLOCK(pfault_lock);
537 static LIST_HEAD(pfault_list);
539 static void pfault_interrupt(struct ext_code ext_code,
540 unsigned int param32, unsigned long param64)
542 struct task_struct *tsk;
547 * Get the external interruption subcode & pfault
548 * initial/completion signal bit. VM stores this
549 * in the 'cpu address' field associated with the
550 * external interrupt.
552 subcode = ext_code.subcode;
553 if ((subcode & 0xff00) != __SUBCODE_MASK)
555 inc_irq_stat(IRQEXT_PFL);
556 /* Get the token (= pid of the affected task). */
557 pid = sizeof(void *) == 4 ? param32 : param64;
559 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
561 get_task_struct(tsk);
565 spin_lock(&pfault_lock);
566 if (subcode & 0x0080) {
567 /* signal bit is set -> a page has been swapped in by VM */
568 if (tsk->thread.pfault_wait == 1) {
569 /* Initial interrupt was faster than the completion
570 * interrupt. pfault_wait is valid. Set pfault_wait
571 * back to zero and wake up the process. This can
572 * safely be done because the task is still sleeping
573 * and can't produce new pfaults. */
574 tsk->thread.pfault_wait = 0;
575 list_del(&tsk->thread.list);
576 wake_up_process(tsk);
577 put_task_struct(tsk);
579 /* Completion interrupt was faster than initial
580 * interrupt. Set pfault_wait to -1 so the initial
581 * interrupt doesn't put the task to sleep.
582 * If the task is not running, ignore the completion
583 * interrupt since it must be a leftover of a PFAULT
584 * CANCEL operation which didn't remove all pending
585 * completion interrupts. */
586 if (tsk->state == TASK_RUNNING)
587 tsk->thread.pfault_wait = -1;
590 /* signal bit not set -> a real page is missing. */
591 if (WARN_ON_ONCE(tsk != current))
593 if (tsk->thread.pfault_wait == 1) {
594 /* Already on the list with a reference: put to sleep */
595 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
596 set_tsk_need_resched(tsk);
597 } else if (tsk->thread.pfault_wait == -1) {
598 /* Completion interrupt was faster than the initial
599 * interrupt (pfault_wait == -1). Set pfault_wait
600 * back to zero and exit. */
601 tsk->thread.pfault_wait = 0;
603 /* Initial interrupt arrived before completion
604 * interrupt. Let the task sleep.
605 * An extra task reference is needed since a different
606 * cpu may set the task state to TASK_RUNNING again
607 * before the scheduler is reached. */
608 get_task_struct(tsk);
609 tsk->thread.pfault_wait = 1;
610 list_add(&tsk->thread.list, &pfault_list);
611 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
612 set_tsk_need_resched(tsk);
616 spin_unlock(&pfault_lock);
617 put_task_struct(tsk);
620 static int pfault_cpu_notify(struct notifier_block *self, unsigned long action,
623 struct thread_struct *thread, *next;
624 struct task_struct *tsk;
626 switch (action & ~CPU_TASKS_FROZEN) {
628 spin_lock_irq(&pfault_lock);
629 list_for_each_entry_safe(thread, next, &pfault_list, list) {
630 thread->pfault_wait = 0;
631 list_del(&thread->list);
632 tsk = container_of(thread, struct task_struct, thread);
633 wake_up_process(tsk);
634 put_task_struct(tsk);
636 spin_unlock_irq(&pfault_lock);
644 static int __init pfault_irq_init(void)
648 rc = register_external_interrupt(0x2603, pfault_interrupt);
651 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
654 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
655 hotcpu_notifier(pfault_cpu_notify, 0);
659 unregister_external_interrupt(0x2603, pfault_interrupt);
664 early_initcall(pfault_irq_init);
666 #endif /* CONFIG_PFAULT */