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
54 static unsigned long store_indication __read_mostly;
57 static int __init fault_init(void)
59 if (test_facility(75))
60 store_indication = 0xc00;
63 early_initcall(fault_init);
66 static inline int notify_page_fault(struct pt_regs *regs)
70 /* kprobe_running() needs smp_processor_id() */
71 if (kprobes_built_in() && !user_mode(regs)) {
73 if (kprobe_running() && kprobe_fault_handler(regs, 14))
82 * Unlock any spinlocks which will prevent us from getting the
85 void bust_spinlocks(int yes)
90 int loglevel_save = console_loglevel;
94 * OK, the message is on the console. Now we call printk()
95 * without oops_in_progress set so that printk will give klogd
96 * a poke. Hold onto your hats...
98 console_loglevel = 15;
100 console_loglevel = loglevel_save;
105 * Returns the address space associated with the fault.
106 * Returns 0 for kernel space and 1 for user space.
108 static inline int user_space_fault(unsigned long trans_exc_code)
111 * The lowest two bits of the translation exception
112 * identification indicate which paging table was used.
115 if (trans_exc_code == 2)
116 /* Access via secondary space, set_fs setting decides */
117 return current->thread.mm_segment.ar4;
118 if (s390_user_mode == HOME_SPACE_MODE)
119 /* User space if the access has been done via home space. */
120 return trans_exc_code == 3;
122 * If the user space is not the home space the kernel runs in home
123 * space. Access via secondary space has already been covered,
124 * access via primary space or access register is from user space
125 * and access via home space is from the kernel.
127 return trans_exc_code != 3;
130 static inline void report_user_fault(struct pt_regs *regs, long signr)
132 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
134 if (!unhandled_signal(current, signr))
136 if (!printk_ratelimit())
138 printk(KERN_ALERT "User process fault: interruption code 0x%X ",
140 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
141 printk(KERN_CONT "\n");
142 printk(KERN_ALERT "failing address: %lX\n",
143 regs->int_parm_long & __FAIL_ADDR_MASK);
148 * Send SIGSEGV to task. This is an external routine
149 * to keep the stack usage of do_page_fault small.
151 static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
155 report_user_fault(regs, SIGSEGV);
156 si.si_signo = SIGSEGV;
157 si.si_code = si_code;
158 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
159 force_sig_info(SIGSEGV, &si, current);
162 static noinline void do_no_context(struct pt_regs *regs)
164 const struct exception_table_entry *fixup;
165 unsigned long address;
167 /* Are we prepared to handle this kernel fault? */
168 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
170 regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
175 * Oops. The kernel tried to access some bad page. We'll have to
176 * terminate things with extreme prejudice.
178 address = regs->int_parm_long & __FAIL_ADDR_MASK;
179 if (!user_space_fault(regs->int_parm_long))
180 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
181 " at virtual kernel address %p\n", (void *)address);
183 printk(KERN_ALERT "Unable to handle kernel paging request"
184 " at virtual user address %p\n", (void *)address);
190 static noinline void do_low_address(struct pt_regs *regs)
192 /* Low-address protection hit in kernel mode means
193 NULL pointer write access in kernel mode. */
194 if (regs->psw.mask & PSW_MASK_PSTATE) {
195 /* Low-address protection hit in user mode 'cannot happen'. */
196 die (regs, "Low-address protection");
203 static noinline void do_sigbus(struct pt_regs *regs)
205 struct task_struct *tsk = current;
209 * Send a sigbus, regardless of whether we were in kernel
212 si.si_signo = SIGBUS;
214 si.si_code = BUS_ADRERR;
215 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
216 force_sig_info(SIGBUS, &si, tsk);
219 static noinline void do_fault_error(struct pt_regs *regs, int fault)
224 case VM_FAULT_BADACCESS:
225 case VM_FAULT_BADMAP:
226 /* Bad memory access. Check if it is kernel or user space. */
227 if (user_mode(regs)) {
228 /* User mode accesses just cause a SIGSEGV */
229 si_code = (fault == VM_FAULT_BADMAP) ?
230 SEGV_MAPERR : SEGV_ACCERR;
231 do_sigsegv(regs, si_code);
234 case VM_FAULT_BADCONTEXT:
237 case VM_FAULT_SIGNAL:
238 if (!user_mode(regs))
241 default: /* fault & VM_FAULT_ERROR */
242 if (fault & VM_FAULT_OOM) {
243 if (!user_mode(regs))
246 pagefault_out_of_memory();
247 } else if (fault & VM_FAULT_SIGBUS) {
248 /* Kernel mode? Handle exceptions or die */
249 if (!user_mode(regs))
260 * This routine handles page faults. It determines the address,
261 * and the problem, and then passes it off to one of the appropriate
264 * interruption code (int_code):
265 * 04 Protection -> Write-Protection (suprression)
266 * 10 Segment translation -> Not present (nullification)
267 * 11 Page translation -> Not present (nullification)
268 * 3b Region third trans. -> Not present (nullification)
270 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;
280 if (notify_page_fault(regs))
285 trans_exc_code = regs->int_parm_long;
288 * Verify that the fault happened in user space, that
289 * we are not in an interrupt and that there is a
292 fault = VM_FAULT_BADCONTEXT;
293 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
296 address = trans_exc_code & __FAIL_ADDR_MASK;
297 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
298 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
299 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
300 flags |= FAULT_FLAG_WRITE;
301 down_read(&mm->mmap_sem);
304 if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
305 address = __gmap_fault(address,
306 (struct gmap *) S390_lowcore.gmap);
307 if (address == -EFAULT) {
308 fault = VM_FAULT_BADMAP;
311 if (address == -ENOMEM) {
312 fault = VM_FAULT_OOM;
319 fault = VM_FAULT_BADMAP;
320 vma = find_vma(mm, address);
324 if (unlikely(vma->vm_start > address)) {
325 if (!(vma->vm_flags & VM_GROWSDOWN))
327 if (expand_stack(vma, address))
332 * Ok, we have a good vm_area for this memory access, so
335 fault = VM_FAULT_BADACCESS;
336 if (unlikely(!(vma->vm_flags & access)))
339 if (is_vm_hugetlb_page(vma))
340 address &= HPAGE_MASK;
342 * If for any reason at all we couldn't handle the fault,
343 * make sure we exit gracefully rather than endlessly redo
346 fault = handle_mm_fault(mm, vma, address, flags);
347 /* No reason to continue if interrupted by SIGKILL. */
348 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
349 fault = VM_FAULT_SIGNAL;
352 if (unlikely(fault & VM_FAULT_ERROR))
356 * Major/minor page fault accounting is only done on the
357 * initial attempt. If we go through a retry, it is extremely
358 * likely that the page will be found in page cache at that point.
360 if (flags & FAULT_FLAG_ALLOW_RETRY) {
361 if (fault & VM_FAULT_MAJOR) {
363 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
367 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
370 if (fault & VM_FAULT_RETRY) {
371 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
373 flags &= ~FAULT_FLAG_ALLOW_RETRY;
374 flags |= FAULT_FLAG_TRIED;
375 down_read(&mm->mmap_sem);
380 * The instruction that caused the program check will
381 * be repeated. Don't signal single step via SIGTRAP.
383 clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
386 up_read(&mm->mmap_sem);
391 void __kprobes do_protection_exception(struct pt_regs *regs)
393 unsigned long trans_exc_code;
396 trans_exc_code = regs->int_parm_long;
397 /* Protection exception is suppressing, decrement psw address. */
398 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
400 * Check for low-address protection. This needs to be treated
401 * as a special case because the translation exception code
402 * field is not guaranteed to contain valid data in this case.
404 if (unlikely(!(trans_exc_code & 4))) {
405 do_low_address(regs);
408 fault = do_exception(regs, VM_WRITE);
410 do_fault_error(regs, fault);
413 void __kprobes do_dat_exception(struct pt_regs *regs)
417 access = VM_READ | VM_EXEC | VM_WRITE;
418 fault = do_exception(regs, access);
420 do_fault_error(regs, fault);
424 void __kprobes do_asce_exception(struct pt_regs *regs)
426 struct mm_struct *mm = current->mm;
427 struct vm_area_struct *vma;
428 unsigned long trans_exc_code;
430 trans_exc_code = regs->int_parm_long;
431 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
434 down_read(&mm->mmap_sem);
435 vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
436 up_read(&mm->mmap_sem);
439 update_mm(mm, current);
443 /* User mode accesses just cause a SIGSEGV */
444 if (user_mode(regs)) {
445 do_sigsegv(regs, SEGV_MAPERR);
454 int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
459 /* Emulate a uaccess fault from kernel mode. */
460 regs.psw.mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_MCHECK;
461 if (!irqs_disabled())
462 regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
463 regs.psw.addr = (unsigned long) __builtin_return_address(0);
464 regs.psw.addr |= PSW_ADDR_AMODE;
465 regs.int_code = pgm_int_code;
466 regs.int_parm_long = (uaddr & PAGE_MASK) | 2;
467 access = write ? VM_WRITE : VM_READ;
468 fault = do_exception(®s, access);
470 * Since the fault happened in kernel mode while performing a uaccess
471 * all we need to do now is emulating a fixup in case "fault" is not
473 * For the calling uaccess functions this results always in -EFAULT.
475 return fault ? -EFAULT : 0;
480 * 'pfault' pseudo page faults routines.
482 static int pfault_disable;
484 static int __init nopfault(char *str)
490 __setup("nopfault", nopfault);
492 struct pfault_refbk {
501 } __attribute__ ((packed, aligned(8)));
503 int pfault_init(void)
505 struct pfault_refbk refbk = {
510 .refgaddr = __LC_CURRENT_PID,
511 .refselmk = 1ULL << 48,
512 .refcmpmk = 1ULL << 48,
513 .reserved = __PF_RES_FIELD };
519 " diag %1,%0,0x258\n"
524 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
528 void pfault_fini(void)
530 struct pfault_refbk refbk = {
543 : : "a" (&refbk), "m" (refbk) : "cc");
546 static DEFINE_SPINLOCK(pfault_lock);
547 static LIST_HEAD(pfault_list);
549 static void pfault_interrupt(struct ext_code ext_code,
550 unsigned int param32, unsigned long param64)
552 struct task_struct *tsk;
557 * Get the external interruption subcode & pfault
558 * initial/completion signal bit. VM stores this
559 * in the 'cpu address' field associated with the
560 * external interrupt.
562 subcode = ext_code.subcode;
563 if ((subcode & 0xff00) != __SUBCODE_MASK)
565 kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++;
566 /* Get the token (= pid of the affected task). */
567 pid = sizeof(void *) == 4 ? param32 : param64;
569 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
571 get_task_struct(tsk);
575 spin_lock(&pfault_lock);
576 if (subcode & 0x0080) {
577 /* signal bit is set -> a page has been swapped in by VM */
578 if (tsk->thread.pfault_wait == 1) {
579 /* Initial interrupt was faster than the completion
580 * interrupt. pfault_wait is valid. Set pfault_wait
581 * back to zero and wake up the process. This can
582 * safely be done because the task is still sleeping
583 * and can't produce new pfaults. */
584 tsk->thread.pfault_wait = 0;
585 list_del(&tsk->thread.list);
586 wake_up_process(tsk);
587 put_task_struct(tsk);
589 /* Completion interrupt was faster than initial
590 * interrupt. Set pfault_wait to -1 so the initial
591 * interrupt doesn't put the task to sleep.
592 * If the task is not running, ignore the completion
593 * interrupt since it must be a leftover of a PFAULT
594 * CANCEL operation which didn't remove all pending
595 * completion interrupts. */
596 if (tsk->state == TASK_RUNNING)
597 tsk->thread.pfault_wait = -1;
600 /* signal bit not set -> a real page is missing. */
601 if (WARN_ON_ONCE(tsk != current))
603 if (tsk->thread.pfault_wait == 1) {
604 /* Already on the list with a reference: put to sleep */
605 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
606 set_tsk_need_resched(tsk);
607 } else if (tsk->thread.pfault_wait == -1) {
608 /* Completion interrupt was faster than the initial
609 * interrupt (pfault_wait == -1). Set pfault_wait
610 * back to zero and exit. */
611 tsk->thread.pfault_wait = 0;
613 /* Initial interrupt arrived before completion
614 * interrupt. Let the task sleep.
615 * An extra task reference is needed since a different
616 * cpu may set the task state to TASK_RUNNING again
617 * before the scheduler is reached. */
618 get_task_struct(tsk);
619 tsk->thread.pfault_wait = 1;
620 list_add(&tsk->thread.list, &pfault_list);
621 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
622 set_tsk_need_resched(tsk);
626 spin_unlock(&pfault_lock);
627 put_task_struct(tsk);
630 static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
631 unsigned long action, void *hcpu)
633 struct thread_struct *thread, *next;
634 struct task_struct *tsk;
636 switch (action & ~CPU_TASKS_FROZEN) {
638 spin_lock_irq(&pfault_lock);
639 list_for_each_entry_safe(thread, next, &pfault_list, list) {
640 thread->pfault_wait = 0;
641 list_del(&thread->list);
642 tsk = container_of(thread, struct task_struct, thread);
643 wake_up_process(tsk);
644 put_task_struct(tsk);
646 spin_unlock_irq(&pfault_lock);
654 static int __init pfault_irq_init(void)
658 rc = register_external_interrupt(0x2603, pfault_interrupt);
661 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
664 service_subclass_irq_register();
665 hotcpu_notifier(pfault_cpu_notify, 0);
669 unregister_external_interrupt(0x2603, pfault_interrupt);
674 early_initcall(pfault_irq_init);
676 #endif /* CONFIG_PFAULT */