527 lines
13 KiB
C
527 lines
13 KiB
C
/*
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* arch/s390/mm/fault.c
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*
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* S390 version
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* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Hartmut Penner (hp@de.ibm.com)
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* Ulrich Weigand (uweigand@de.ibm.com)
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*
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* Derived from "arch/i386/mm/fault.c"
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* Copyright (C) 1995 Linus Torvalds
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*/
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/init.h>
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#include <linux/console.h>
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#include <linux/module.h>
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#include <linux/hardirq.h>
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#include <linux/kprobes.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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#include <asm/pgtable.h>
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#include <asm/kdebug.h>
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#include <asm/s390_ext.h>
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#ifndef CONFIG_64BIT
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#define __FAIL_ADDR_MASK 0x7ffff000
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#define __FIXUP_MASK 0x7fffffff
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#define __SUBCODE_MASK 0x0200
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#define __PF_RES_FIELD 0ULL
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#else /* CONFIG_64BIT */
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#define __FAIL_ADDR_MASK -4096L
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#define __FIXUP_MASK ~0L
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#define __SUBCODE_MASK 0x0600
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#define __PF_RES_FIELD 0x8000000000000000ULL
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#endif /* CONFIG_64BIT */
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#ifdef CONFIG_SYSCTL
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extern int sysctl_userprocess_debug;
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#endif
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extern void die(const char *,struct pt_regs *,long);
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#ifdef CONFIG_KPROBES
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ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
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int register_page_fault_notifier(struct notifier_block *nb)
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{
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return atomic_notifier_chain_register(¬ify_page_fault_chain, nb);
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}
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int unregister_page_fault_notifier(struct notifier_block *nb)
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{
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return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb);
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}
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static inline int notify_page_fault(enum die_val val, const char *str,
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struct pt_regs *regs, long err, int trap, int sig)
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{
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struct die_args args = {
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.regs = regs,
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.str = str,
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.err = err,
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.trapnr = trap,
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.signr = sig
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};
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return atomic_notifier_call_chain(¬ify_page_fault_chain, val, &args);
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}
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#else
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static inline int notify_page_fault(enum die_val val, const char *str,
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struct pt_regs *regs, long err, int trap, int sig)
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{
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return NOTIFY_DONE;
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}
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#endif
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extern spinlock_t timerlist_lock;
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/*
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* Unlock any spinlocks which will prevent us from getting the
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* message out (timerlist_lock is acquired through the
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* console unblank code)
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*/
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void bust_spinlocks(int yes)
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{
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if (yes) {
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oops_in_progress = 1;
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} else {
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int loglevel_save = console_loglevel;
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console_unblank();
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oops_in_progress = 0;
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/*
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* OK, the message is on the console. Now we call printk()
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* without oops_in_progress set so that printk will give klogd
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* a poke. Hold onto your hats...
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*/
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console_loglevel = 15;
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printk(" ");
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console_loglevel = loglevel_save;
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}
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}
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/*
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* Check which address space is addressed by the access
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* register in S390_lowcore.exc_access_id.
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* Returns 1 for user space and 0 for kernel space.
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*/
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static int __check_access_register(struct pt_regs *regs, int error_code)
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{
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int areg = S390_lowcore.exc_access_id;
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if (areg == 0)
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/* Access via access register 0 -> kernel address */
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return 0;
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save_access_regs(current->thread.acrs);
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if (regs && areg < NUM_ACRS && current->thread.acrs[areg] <= 1)
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/*
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* access register contains 0 -> kernel address,
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* access register contains 1 -> user space address
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*/
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return current->thread.acrs[areg];
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/* Something unhealthy was done with the access registers... */
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die("page fault via unknown access register", regs, error_code);
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do_exit(SIGKILL);
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return 0;
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}
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/*
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* Check which address space the address belongs to.
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* Returns 1 for user space and 0 for kernel space.
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*/
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static inline int check_user_space(struct pt_regs *regs, int error_code)
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{
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/*
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* The lowest two bits of S390_lowcore.trans_exc_code indicate
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* which paging table was used:
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* 0: Primary Segment Table Descriptor
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* 1: STD determined via access register
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* 2: Secondary Segment Table Descriptor
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* 3: Home Segment Table Descriptor
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*/
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int descriptor = S390_lowcore.trans_exc_code & 3;
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if (unlikely(descriptor == 1))
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return __check_access_register(regs, error_code);
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if (descriptor == 2)
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return current->thread.mm_segment.ar4;
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return descriptor != 0;
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}
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/*
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* Send SIGSEGV to task. This is an external routine
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* to keep the stack usage of do_page_fault small.
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*/
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static void do_sigsegv(struct pt_regs *regs, unsigned long error_code,
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int si_code, unsigned long address)
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{
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struct siginfo si;
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#if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG)
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#if defined(CONFIG_SYSCTL)
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if (sysctl_userprocess_debug)
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#endif
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{
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printk("User process fault: interruption code 0x%lX\n",
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error_code);
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printk("failing address: %lX\n", address);
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show_regs(regs);
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}
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#endif
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si.si_signo = SIGSEGV;
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si.si_code = si_code;
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si.si_addr = (void __user *) address;
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force_sig_info(SIGSEGV, &si, current);
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}
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*
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* error_code:
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* 04 Protection -> Write-Protection (suprression)
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* 10 Segment translation -> Not present (nullification)
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* 11 Page translation -> Not present (nullification)
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* 3b Region third trans. -> Not present (nullification)
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*/
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static inline void __kprobes
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do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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struct vm_area_struct * vma;
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unsigned long address;
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int user_address;
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const struct exception_table_entry *fixup;
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int si_code = SEGV_MAPERR;
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tsk = current;
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mm = tsk->mm;
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if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14,
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SIGSEGV) == NOTIFY_STOP)
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return;
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/*
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* Check for low-address protection. This needs to be treated
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* as a special case because the translation exception code
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* field is not guaranteed to contain valid data in this case.
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*/
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if (is_protection && !(S390_lowcore.trans_exc_code & 4)) {
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/* Low-address protection hit in kernel mode means
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NULL pointer write access in kernel mode. */
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if (!(regs->psw.mask & PSW_MASK_PSTATE)) {
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address = 0;
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user_address = 0;
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goto no_context;
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}
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/* Low-address protection hit in user mode 'cannot happen'. */
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die ("Low-address protection", regs, error_code);
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do_exit(SIGKILL);
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}
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/*
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* get the failing address
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* more specific the segment and page table portion of
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* the address
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*/
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address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK;
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user_address = check_user_space(regs, error_code);
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/*
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* Verify that the fault happened in user space, that
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* we are not in an interrupt and that there is a
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* user context.
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*/
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if (user_address == 0 || in_atomic() || !mm)
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goto no_context;
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/*
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* When we get here, the fault happened in the current
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* task's user address space, so we can switch on the
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* interrupts again and then search the VMAs
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*/
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local_irq_enable();
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if (expand_stack(vma, address))
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goto bad_area;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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si_code = SEGV_ACCERR;
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if (!is_protection) {
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/* page not present, check vm flags */
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if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
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goto bad_area;
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} else {
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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}
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survive:
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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switch (handle_mm_fault(mm, vma, address, is_protection)) {
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case VM_FAULT_MINOR:
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tsk->min_flt++;
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break;
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case VM_FAULT_MAJOR:
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tsk->maj_flt++;
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break;
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case VM_FAULT_SIGBUS:
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goto do_sigbus;
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case VM_FAULT_OOM:
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goto out_of_memory;
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default:
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BUG();
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}
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up_read(&mm->mmap_sem);
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/*
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* The instruction that caused the program check will
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* be repeated. Don't signal single step via SIGTRAP.
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*/
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clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
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return;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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bad_area:
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up_read(&mm->mmap_sem);
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/* User mode accesses just cause a SIGSEGV */
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if (regs->psw.mask & PSW_MASK_PSTATE) {
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tsk->thread.prot_addr = address;
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tsk->thread.trap_no = error_code;
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do_sigsegv(regs, error_code, si_code, address);
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return;
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}
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no_context:
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/* Are we prepared to handle this kernel fault? */
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fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK);
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if (fixup) {
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regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
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return;
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}
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice.
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*/
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if (user_address == 0)
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printk(KERN_ALERT "Unable to handle kernel pointer dereference"
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" at virtual kernel address %p\n", (void *)address);
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else
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printk(KERN_ALERT "Unable to handle kernel paging request"
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" at virtual user address %p\n", (void *)address);
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die("Oops", regs, error_code);
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do_exit(SIGKILL);
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/*
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* We ran out of memory, or some other thing happened to us that made
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* us unable to handle the page fault gracefully.
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*/
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out_of_memory:
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up_read(&mm->mmap_sem);
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if (is_init(tsk)) {
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yield();
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down_read(&mm->mmap_sem);
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goto survive;
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}
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printk("VM: killing process %s\n", tsk->comm);
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if (regs->psw.mask & PSW_MASK_PSTATE)
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do_exit(SIGKILL);
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goto no_context;
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do_sigbus:
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up_read(&mm->mmap_sem);
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/*
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* Send a sigbus, regardless of whether we were in kernel
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* or user mode.
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*/
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tsk->thread.prot_addr = address;
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tsk->thread.trap_no = error_code;
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force_sig(SIGBUS, tsk);
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/* Kernel mode? Handle exceptions or die */
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if (!(regs->psw.mask & PSW_MASK_PSTATE))
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goto no_context;
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}
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void do_protection_exception(struct pt_regs *regs, unsigned long error_code)
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{
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regs->psw.addr -= (error_code >> 16);
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do_exception(regs, 4, 1);
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}
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void do_dat_exception(struct pt_regs *regs, unsigned long error_code)
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{
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do_exception(regs, error_code & 0xff, 0);
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}
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#ifdef CONFIG_PFAULT
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/*
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* 'pfault' pseudo page faults routines.
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*/
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static ext_int_info_t ext_int_pfault;
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static int pfault_disable = 0;
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static int __init nopfault(char *str)
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{
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pfault_disable = 1;
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return 1;
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}
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__setup("nopfault", nopfault);
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typedef struct {
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__u16 refdiagc;
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__u16 reffcode;
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__u16 refdwlen;
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__u16 refversn;
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__u64 refgaddr;
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__u64 refselmk;
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__u64 refcmpmk;
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__u64 reserved;
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} __attribute__ ((packed)) pfault_refbk_t;
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int pfault_init(void)
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{
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pfault_refbk_t refbk =
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{ 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48,
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__PF_RES_FIELD };
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int rc;
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if (!MACHINE_IS_VM || pfault_disable)
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return -1;
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asm volatile(
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" diag %1,%0,0x258\n"
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"0: j 2f\n"
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"1: la %0,8\n"
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"2:\n"
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EX_TABLE(0b,1b)
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: "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
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__ctl_set_bit(0, 9);
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return rc;
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}
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void pfault_fini(void)
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{
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pfault_refbk_t refbk =
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{ 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL };
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if (!MACHINE_IS_VM || pfault_disable)
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return;
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__ctl_clear_bit(0,9);
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asm volatile(
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" diag %0,0,0x258\n"
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"0:\n"
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EX_TABLE(0b,0b)
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: : "a" (&refbk), "m" (refbk) : "cc");
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}
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asmlinkage void
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pfault_interrupt(__u16 error_code)
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{
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struct task_struct *tsk;
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__u16 subcode;
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/*
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* Get the external interruption subcode & pfault
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* initial/completion signal bit. VM stores this
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* in the 'cpu address' field associated with the
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* external interrupt.
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*/
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subcode = S390_lowcore.cpu_addr;
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if ((subcode & 0xff00) != __SUBCODE_MASK)
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return;
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/*
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* Get the token (= address of the task structure of the affected task).
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*/
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tsk = *(struct task_struct **) __LC_PFAULT_INTPARM;
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if (subcode & 0x0080) {
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/* signal bit is set -> a page has been swapped in by VM */
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if (xchg(&tsk->thread.pfault_wait, -1) != 0) {
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/* Initial interrupt was faster than the completion
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* interrupt. pfault_wait is valid. Set pfault_wait
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* back to zero and wake up the process. This can
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* safely be done because the task is still sleeping
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* and can't produce new pfaults. */
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tsk->thread.pfault_wait = 0;
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wake_up_process(tsk);
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put_task_struct(tsk);
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}
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} else {
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/* signal bit not set -> a real page is missing. */
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get_task_struct(tsk);
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set_task_state(tsk, TASK_UNINTERRUPTIBLE);
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if (xchg(&tsk->thread.pfault_wait, 1) != 0) {
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/* Completion interrupt was faster than the initial
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* interrupt (swapped in a -1 for pfault_wait). Set
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* pfault_wait back to zero and exit. This can be
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* done safely because tsk is running in kernel
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* mode and can't produce new pfaults. */
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tsk->thread.pfault_wait = 0;
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set_task_state(tsk, TASK_RUNNING);
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put_task_struct(tsk);
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} else
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set_tsk_need_resched(tsk);
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}
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}
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void __init pfault_irq_init(void)
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{
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if (!MACHINE_IS_VM)
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return;
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/*
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* Try to get pfault pseudo page faults going.
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*/
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if (register_early_external_interrupt(0x2603, pfault_interrupt,
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&ext_int_pfault) != 0)
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panic("Couldn't request external interrupt 0x2603");
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if (pfault_init() == 0)
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return;
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/* Tough luck, no pfault. */
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pfault_disable = 1;
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unregister_early_external_interrupt(0x2603, pfault_interrupt,
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&ext_int_pfault);
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}
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#endif
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