Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / arch / s390 / mm / fault.c
diff --git a/kernel/arch/s390/mm/fault.c b/kernel/arch/s390/mm/fault.c
new file mode 100644 (file)
index 0000000..4c8f5d7
--- /dev/null
@@ -0,0 +1,758 @@
+/*
+ *  S390 version
+ *    Copyright IBM Corp. 1999
+ *    Author(s): Hartmut Penner (hp@de.ibm.com)
+ *               Ulrich Weigand (uweigand@de.ibm.com)
+ *
+ *  Derived from "arch/i386/mm/fault.c"
+ *    Copyright (C) 1995  Linus Torvalds
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/perf_event.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/compat.h>
+#include <linux/smp.h>
+#include <linux/kdebug.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/hardirq.h>
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+#include <linux/hugetlb.h>
+#include <asm/asm-offsets.h>
+#include <asm/pgtable.h>
+#include <asm/irq.h>
+#include <asm/mmu_context.h>
+#include <asm/facility.h>
+#include "../kernel/entry.h"
+
+#define __FAIL_ADDR_MASK -4096L
+#define __SUBCODE_MASK 0x0600
+#define __PF_RES_FIELD 0x8000000000000000ULL
+
+#define VM_FAULT_BADCONTEXT    0x010000
+#define VM_FAULT_BADMAP                0x020000
+#define VM_FAULT_BADACCESS     0x040000
+#define VM_FAULT_SIGNAL                0x080000
+#define VM_FAULT_PFAULT                0x100000
+
+static unsigned long store_indication __read_mostly;
+
+static int __init fault_init(void)
+{
+       if (test_facility(75))
+               store_indication = 0xc00;
+       return 0;
+}
+early_initcall(fault_init);
+
+static inline int notify_page_fault(struct pt_regs *regs)
+{
+       int ret = 0;
+
+       /* kprobe_running() needs smp_processor_id() */
+       if (kprobes_built_in() && !user_mode(regs)) {
+               preempt_disable();
+               if (kprobe_running() && kprobe_fault_handler(regs, 14))
+                       ret = 1;
+               preempt_enable();
+       }
+       return ret;
+}
+
+
+/*
+ * Unlock any spinlocks which will prevent us from getting the
+ * message out.
+ */
+void bust_spinlocks(int yes)
+{
+       if (yes) {
+               oops_in_progress = 1;
+       } else {
+               int loglevel_save = console_loglevel;
+               console_unblank();
+               oops_in_progress = 0;
+               /*
+                * OK, the message is on the console.  Now we call printk()
+                * without oops_in_progress set so that printk will give klogd
+                * a poke.  Hold onto your hats...
+                */
+               console_loglevel = 15;
+               printk(" ");
+               console_loglevel = loglevel_save;
+       }
+}
+
+/*
+ * Returns the address space associated with the fault.
+ * Returns 0 for kernel space and 1 for user space.
+ */
+static inline int user_space_fault(struct pt_regs *regs)
+{
+       unsigned long trans_exc_code;
+
+       /*
+        * The lowest two bits of the translation exception
+        * identification indicate which paging table was used.
+        */
+       trans_exc_code = regs->int_parm_long & 3;
+       if (trans_exc_code == 3) /* home space -> kernel */
+               return 0;
+       if (user_mode(regs))
+               return 1;
+       if (trans_exc_code == 2) /* secondary space -> set_fs */
+               return current->thread.mm_segment.ar4;
+       if (current->flags & PF_VCPU)
+               return 1;
+       return 0;
+}
+
+static int bad_address(void *p)
+{
+       unsigned long dummy;
+
+       return probe_kernel_address((unsigned long *)p, dummy);
+}
+
+static void dump_pagetable(unsigned long asce, unsigned long address)
+{
+       unsigned long *table = __va(asce & PAGE_MASK);
+
+       pr_alert("AS:%016lx ", asce);
+       switch (asce & _ASCE_TYPE_MASK) {
+       case _ASCE_TYPE_REGION1:
+               table = table + ((address >> 53) & 0x7ff);
+               if (bad_address(table))
+                       goto bad;
+               pr_cont("R1:%016lx ", *table);
+               if (*table & _REGION_ENTRY_INVALID)
+                       goto out;
+               table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+               /* fallthrough */
+       case _ASCE_TYPE_REGION2:
+               table = table + ((address >> 42) & 0x7ff);
+               if (bad_address(table))
+                       goto bad;
+               pr_cont("R2:%016lx ", *table);
+               if (*table & _REGION_ENTRY_INVALID)
+                       goto out;
+               table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+               /* fallthrough */
+       case _ASCE_TYPE_REGION3:
+               table = table + ((address >> 31) & 0x7ff);
+               if (bad_address(table))
+                       goto bad;
+               pr_cont("R3:%016lx ", *table);
+               if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
+                       goto out;
+               table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
+               /* fallthrough */
+       case _ASCE_TYPE_SEGMENT:
+               table = table + ((address >> 20) & 0x7ff);
+               if (bad_address(table))
+                       goto bad;
+               pr_cont("S:%016lx ", *table);
+               if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
+                       goto out;
+               table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
+       }
+       table = table + ((address >> 12) & 0xff);
+       if (bad_address(table))
+               goto bad;
+       pr_cont("P:%016lx ", *table);
+out:
+       pr_cont("\n");
+       return;
+bad:
+       pr_cont("BAD\n");
+}
+
+static void dump_fault_info(struct pt_regs *regs)
+{
+       unsigned long asce;
+
+       pr_alert("Fault in ");
+       switch (regs->int_parm_long & 3) {
+       case 3:
+               pr_cont("home space ");
+               break;
+       case 2:
+               pr_cont("secondary space ");
+               break;
+       case 1:
+               pr_cont("access register ");
+               break;
+       case 0:
+               pr_cont("primary space ");
+               break;
+       }
+       pr_cont("mode while using ");
+       if (!user_space_fault(regs)) {
+               asce = S390_lowcore.kernel_asce;
+               pr_cont("kernel ");
+       }
+#ifdef CONFIG_PGSTE
+       else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
+               struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
+               asce = gmap->asce;
+               pr_cont("gmap ");
+       }
+#endif
+       else {
+               asce = S390_lowcore.user_asce;
+               pr_cont("user ");
+       }
+       pr_cont("ASCE.\n");
+       dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
+}
+
+static inline void report_user_fault(struct pt_regs *regs, long signr)
+{
+       if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
+               return;
+       if (!unhandled_signal(current, signr))
+               return;
+       if (!printk_ratelimit())
+               return;
+       printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ",
+              regs->int_code & 0xffff, regs->int_code >> 17);
+       print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
+       printk(KERN_CONT "\n");
+       printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
+              regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
+       dump_fault_info(regs);
+       show_regs(regs);
+}
+
+/*
+ * Send SIGSEGV to task.  This is an external routine
+ * to keep the stack usage of do_page_fault small.
+ */
+static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
+{
+       struct siginfo si;
+
+       report_user_fault(regs, SIGSEGV);
+       si.si_signo = SIGSEGV;
+       si.si_code = si_code;
+       si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
+       force_sig_info(SIGSEGV, &si, current);
+}
+
+static noinline void do_no_context(struct pt_regs *regs)
+{
+       const struct exception_table_entry *fixup;
+       unsigned long address;
+
+       /* Are we prepared to handle this kernel fault?  */
+       fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
+       if (fixup) {
+               regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
+               return;
+       }
+
+       /*
+        * Oops. The kernel tried to access some bad page. We'll have to
+        * terminate things with extreme prejudice.
+        */
+       address = regs->int_parm_long & __FAIL_ADDR_MASK;
+       if (!user_space_fault(regs))
+               printk(KERN_ALERT "Unable to handle kernel pointer dereference"
+                      " in virtual kernel address space\n");
+       else
+               printk(KERN_ALERT "Unable to handle kernel paging request"
+                      " in virtual user address space\n");
+       printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
+              regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
+       dump_fault_info(regs);
+       die(regs, "Oops");
+       do_exit(SIGKILL);
+}
+
+static noinline void do_low_address(struct pt_regs *regs)
+{
+       /* Low-address protection hit in kernel mode means
+          NULL pointer write access in kernel mode.  */
+       if (regs->psw.mask & PSW_MASK_PSTATE) {
+               /* Low-address protection hit in user mode 'cannot happen'. */
+               die (regs, "Low-address protection");
+               do_exit(SIGKILL);
+       }
+
+       do_no_context(regs);
+}
+
+static noinline void do_sigbus(struct pt_regs *regs)
+{
+       struct task_struct *tsk = current;
+       struct siginfo si;
+
+       /*
+        * Send a sigbus, regardless of whether we were in kernel
+        * or user mode.
+        */
+       si.si_signo = SIGBUS;
+       si.si_errno = 0;
+       si.si_code = BUS_ADRERR;
+       si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
+       force_sig_info(SIGBUS, &si, tsk);
+}
+
+static noinline void do_fault_error(struct pt_regs *regs, int fault)
+{
+       int si_code;
+
+       switch (fault) {
+       case VM_FAULT_BADACCESS:
+       case VM_FAULT_BADMAP:
+               /* Bad memory access. Check if it is kernel or user space. */
+               if (user_mode(regs)) {
+                       /* User mode accesses just cause a SIGSEGV */
+                       si_code = (fault == VM_FAULT_BADMAP) ?
+                               SEGV_MAPERR : SEGV_ACCERR;
+                       do_sigsegv(regs, si_code);
+                       return;
+               }
+       case VM_FAULT_BADCONTEXT:
+       case VM_FAULT_PFAULT:
+               do_no_context(regs);
+               break;
+       case VM_FAULT_SIGNAL:
+               if (!user_mode(regs))
+                       do_no_context(regs);
+               break;
+       default: /* fault & VM_FAULT_ERROR */
+               if (fault & VM_FAULT_OOM) {
+                       if (!user_mode(regs))
+                               do_no_context(regs);
+                       else
+                               pagefault_out_of_memory();
+               } else if (fault & VM_FAULT_SIGSEGV) {
+                       /* Kernel mode? Handle exceptions or die */
+                       if (!user_mode(regs))
+                               do_no_context(regs);
+                       else
+                               do_sigsegv(regs, SEGV_MAPERR);
+               } else if (fault & VM_FAULT_SIGBUS) {
+                       /* Kernel mode? Handle exceptions or die */
+                       if (!user_mode(regs))
+                               do_no_context(regs);
+                       else
+                               do_sigbus(regs);
+               } else
+                       BUG();
+               break;
+       }
+}
+
+/*
+ * This routine handles page faults.  It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ *
+ * interruption code (int_code):
+ *   04       Protection           ->  Write-Protection  (suprression)
+ *   10       Segment translation  ->  Not present       (nullification)
+ *   11       Page translation     ->  Not present       (nullification)
+ *   3b       Region third trans.  ->  Not present       (nullification)
+ */
+static inline int do_exception(struct pt_regs *regs, int access)
+{
+#ifdef CONFIG_PGSTE
+       struct gmap *gmap;
+#endif
+       struct task_struct *tsk;
+       struct mm_struct *mm;
+       struct vm_area_struct *vma;
+       unsigned long trans_exc_code;
+       unsigned long address;
+       unsigned int flags;
+       int fault;
+
+       tsk = current;
+       /*
+        * The instruction that caused the program check has
+        * been nullified. Don't signal single step via SIGTRAP.
+        */
+       clear_pt_regs_flag(regs, PIF_PER_TRAP);
+
+       if (notify_page_fault(regs))
+               return 0;
+
+       mm = tsk->mm;
+       trans_exc_code = regs->int_parm_long;
+
+       /*
+        * Verify that the fault happened in user space, that
+        * we are not in an interrupt and that there is a 
+        * user context.
+        */
+       fault = VM_FAULT_BADCONTEXT;
+       if (unlikely(!user_space_fault(regs) || faulthandler_disabled() || !mm))
+               goto out;
+
+       address = trans_exc_code & __FAIL_ADDR_MASK;
+       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+       flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+       if (user_mode(regs))
+               flags |= FAULT_FLAG_USER;
+       if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
+               flags |= FAULT_FLAG_WRITE;
+       down_read(&mm->mmap_sem);
+
+#ifdef CONFIG_PGSTE
+       gmap = (current->flags & PF_VCPU) ?
+               (struct gmap *) S390_lowcore.gmap : NULL;
+       if (gmap) {
+               current->thread.gmap_addr = address;
+               address = __gmap_translate(gmap, address);
+               if (address == -EFAULT) {
+                       fault = VM_FAULT_BADMAP;
+                       goto out_up;
+               }
+               if (gmap->pfault_enabled)
+                       flags |= FAULT_FLAG_RETRY_NOWAIT;
+       }
+#endif
+
+retry:
+       fault = VM_FAULT_BADMAP;
+       vma = find_vma(mm, address);
+       if (!vma)
+               goto out_up;
+
+       if (unlikely(vma->vm_start > address)) {
+               if (!(vma->vm_flags & VM_GROWSDOWN))
+                       goto out_up;
+               if (expand_stack(vma, address))
+                       goto out_up;
+       }
+
+       /*
+        * Ok, we have a good vm_area for this memory access, so
+        * we can handle it..
+        */
+       fault = VM_FAULT_BADACCESS;
+       if (unlikely(!(vma->vm_flags & access)))
+               goto out_up;
+
+       if (is_vm_hugetlb_page(vma))
+               address &= HPAGE_MASK;
+       /*
+        * If for any reason at all we couldn't handle the fault,
+        * make sure we exit gracefully rather than endlessly redo
+        * the fault.
+        */
+       fault = handle_mm_fault(mm, vma, address, flags);
+       /* No reason to continue if interrupted by SIGKILL. */
+       if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
+               fault = VM_FAULT_SIGNAL;
+               goto out;
+       }
+       if (unlikely(fault & VM_FAULT_ERROR))
+               goto out_up;
+
+       /*
+        * Major/minor page fault accounting is only done on the
+        * initial attempt. If we go through a retry, it is extremely
+        * likely that the page will be found in page cache at that point.
+        */
+       if (flags & FAULT_FLAG_ALLOW_RETRY) {
+               if (fault & VM_FAULT_MAJOR) {
+                       tsk->maj_flt++;
+                       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+                                     regs, address);
+               } else {
+                       tsk->min_flt++;
+                       perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+                                     regs, address);
+               }
+               if (fault & VM_FAULT_RETRY) {
+#ifdef CONFIG_PGSTE
+                       if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
+                               /* FAULT_FLAG_RETRY_NOWAIT has been set,
+                                * mmap_sem has not been released */
+                               current->thread.gmap_pfault = 1;
+                               fault = VM_FAULT_PFAULT;
+                               goto out_up;
+                       }
+#endif
+                       /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+                        * of starvation. */
+                       flags &= ~(FAULT_FLAG_ALLOW_RETRY |
+                                  FAULT_FLAG_RETRY_NOWAIT);
+                       flags |= FAULT_FLAG_TRIED;
+                       down_read(&mm->mmap_sem);
+                       goto retry;
+               }
+       }
+#ifdef CONFIG_PGSTE
+       if (gmap) {
+               address =  __gmap_link(gmap, current->thread.gmap_addr,
+                                      address);
+               if (address == -EFAULT) {
+                       fault = VM_FAULT_BADMAP;
+                       goto out_up;
+               }
+               if (address == -ENOMEM) {
+                       fault = VM_FAULT_OOM;
+                       goto out_up;
+               }
+       }
+#endif
+       fault = 0;
+out_up:
+       up_read(&mm->mmap_sem);
+out:
+       return fault;
+}
+
+void do_protection_exception(struct pt_regs *regs)
+{
+       unsigned long trans_exc_code;
+       int fault;
+
+       trans_exc_code = regs->int_parm_long;
+       /*
+        * Protection exceptions are suppressing, decrement psw address.
+        * The exception to this rule are aborted transactions, for these
+        * the PSW already points to the correct location.
+        */
+       if (!(regs->int_code & 0x200))
+               regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
+       /*
+        * Check for low-address protection.  This needs to be treated
+        * as a special case because the translation exception code
+        * field is not guaranteed to contain valid data in this case.
+        */
+       if (unlikely(!(trans_exc_code & 4))) {
+               do_low_address(regs);
+               return;
+       }
+       fault = do_exception(regs, VM_WRITE);
+       if (unlikely(fault))
+               do_fault_error(regs, fault);
+}
+NOKPROBE_SYMBOL(do_protection_exception);
+
+void do_dat_exception(struct pt_regs *regs)
+{
+       int access, fault;
+
+       access = VM_READ | VM_EXEC | VM_WRITE;
+       fault = do_exception(regs, access);
+       if (unlikely(fault))
+               do_fault_error(regs, fault);
+}
+NOKPROBE_SYMBOL(do_dat_exception);
+
+#ifdef CONFIG_PFAULT 
+/*
+ * 'pfault' pseudo page faults routines.
+ */
+static int pfault_disable;
+
+static int __init nopfault(char *str)
+{
+       pfault_disable = 1;
+       return 1;
+}
+
+__setup("nopfault", nopfault);
+
+struct pfault_refbk {
+       u16 refdiagc;
+       u16 reffcode;
+       u16 refdwlen;
+       u16 refversn;
+       u64 refgaddr;
+       u64 refselmk;
+       u64 refcmpmk;
+       u64 reserved;
+} __attribute__ ((packed, aligned(8)));
+
+int pfault_init(void)
+{
+       struct pfault_refbk refbk = {
+               .refdiagc = 0x258,
+               .reffcode = 0,
+               .refdwlen = 5,
+               .refversn = 2,
+               .refgaddr = __LC_CURRENT_PID,
+               .refselmk = 1ULL << 48,
+               .refcmpmk = 1ULL << 48,
+               .reserved = __PF_RES_FIELD };
+        int rc;
+
+       if (pfault_disable)
+               return -1;
+       asm volatile(
+               "       diag    %1,%0,0x258\n"
+               "0:     j       2f\n"
+               "1:     la      %0,8\n"
+               "2:\n"
+               EX_TABLE(0b,1b)
+               : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
+        return rc;
+}
+
+void pfault_fini(void)
+{
+       struct pfault_refbk refbk = {
+               .refdiagc = 0x258,
+               .reffcode = 1,
+               .refdwlen = 5,
+               .refversn = 2,
+       };
+
+       if (pfault_disable)
+               return;
+       asm volatile(
+               "       diag    %0,0,0x258\n"
+               "0:\n"
+               EX_TABLE(0b,0b)
+               : : "a" (&refbk), "m" (refbk) : "cc");
+}
+
+static DEFINE_SPINLOCK(pfault_lock);
+static LIST_HEAD(pfault_list);
+
+static void pfault_interrupt(struct ext_code ext_code,
+                            unsigned int param32, unsigned long param64)
+{
+       struct task_struct *tsk;
+       __u16 subcode;
+       pid_t pid;
+
+       /*
+        * Get the external interruption subcode & pfault
+        * initial/completion signal bit. VM stores this 
+        * in the 'cpu address' field associated with the
+         * external interrupt. 
+        */
+       subcode = ext_code.subcode;
+       if ((subcode & 0xff00) != __SUBCODE_MASK)
+               return;
+       inc_irq_stat(IRQEXT_PFL);
+       /* Get the token (= pid of the affected task). */
+       pid = sizeof(void *) == 4 ? param32 : param64;
+       rcu_read_lock();
+       tsk = find_task_by_pid_ns(pid, &init_pid_ns);
+       if (tsk)
+               get_task_struct(tsk);
+       rcu_read_unlock();
+       if (!tsk)
+               return;
+       spin_lock(&pfault_lock);
+       if (subcode & 0x0080) {
+               /* signal bit is set -> a page has been swapped in by VM */
+               if (tsk->thread.pfault_wait == 1) {
+                       /* Initial interrupt was faster than the completion
+                        * interrupt. pfault_wait is valid. Set pfault_wait
+                        * back to zero and wake up the process. This can
+                        * safely be done because the task is still sleeping
+                        * and can't produce new pfaults. */
+                       tsk->thread.pfault_wait = 0;
+                       list_del(&tsk->thread.list);
+                       wake_up_process(tsk);
+                       put_task_struct(tsk);
+               } else {
+                       /* Completion interrupt was faster than initial
+                        * interrupt. Set pfault_wait to -1 so the initial
+                        * interrupt doesn't put the task to sleep.
+                        * If the task is not running, ignore the completion
+                        * interrupt since it must be a leftover of a PFAULT
+                        * CANCEL operation which didn't remove all pending
+                        * completion interrupts. */
+                       if (tsk->state == TASK_RUNNING)
+                               tsk->thread.pfault_wait = -1;
+               }
+       } else {
+               /* signal bit not set -> a real page is missing. */
+               if (WARN_ON_ONCE(tsk != current))
+                       goto out;
+               if (tsk->thread.pfault_wait == 1) {
+                       /* Already on the list with a reference: put to sleep */
+                       __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+                       set_tsk_need_resched(tsk);
+               } else if (tsk->thread.pfault_wait == -1) {
+                       /* Completion interrupt was faster than the initial
+                        * interrupt (pfault_wait == -1). Set pfault_wait
+                        * back to zero and exit. */
+                       tsk->thread.pfault_wait = 0;
+               } else {
+                       /* Initial interrupt arrived before completion
+                        * interrupt. Let the task sleep.
+                        * An extra task reference is needed since a different
+                        * cpu may set the task state to TASK_RUNNING again
+                        * before the scheduler is reached. */
+                       get_task_struct(tsk);
+                       tsk->thread.pfault_wait = 1;
+                       list_add(&tsk->thread.list, &pfault_list);
+                       __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+                       set_tsk_need_resched(tsk);
+               }
+       }
+out:
+       spin_unlock(&pfault_lock);
+       put_task_struct(tsk);
+}
+
+static int pfault_cpu_notify(struct notifier_block *self, unsigned long action,
+                            void *hcpu)
+{
+       struct thread_struct *thread, *next;
+       struct task_struct *tsk;
+
+       switch (action & ~CPU_TASKS_FROZEN) {
+       case CPU_DEAD:
+               spin_lock_irq(&pfault_lock);
+               list_for_each_entry_safe(thread, next, &pfault_list, list) {
+                       thread->pfault_wait = 0;
+                       list_del(&thread->list);
+                       tsk = container_of(thread, struct task_struct, thread);
+                       wake_up_process(tsk);
+                       put_task_struct(tsk);
+               }
+               spin_unlock_irq(&pfault_lock);
+               break;
+       default:
+               break;
+       }
+       return NOTIFY_OK;
+}
+
+static int __init pfault_irq_init(void)
+{
+       int rc;
+
+       rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
+       if (rc)
+               goto out_extint;
+       rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
+       if (rc)
+               goto out_pfault;
+       irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
+       hotcpu_notifier(pfault_cpu_notify, 0);
+       return 0;
+
+out_pfault:
+       unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
+out_extint:
+       pfault_disable = 1;
+       return rc;
+}
+early_initcall(pfault_irq_init);
+
+#endif /* CONFIG_PFAULT */