xref: /openbmc/linux/arch/s390/mm/fault.c (revision 91c0837e)
11da177e4SLinus Torvalds /*
21da177e4SLinus Torvalds  *  S390 version
3a53c8fabSHeiko Carstens  *    Copyright IBM Corp. 1999
41da177e4SLinus Torvalds  *    Author(s): Hartmut Penner (hp@de.ibm.com)
51da177e4SLinus Torvalds  *               Ulrich Weigand (uweigand@de.ibm.com)
61da177e4SLinus Torvalds  *
71da177e4SLinus Torvalds  *  Derived from "arch/i386/mm/fault.c"
81da177e4SLinus Torvalds  *    Copyright (C) 1995  Linus Torvalds
91da177e4SLinus Torvalds  */
101da177e4SLinus Torvalds 
11052ff461SHeiko Carstens #include <linux/kernel_stat.h>
12cdd6c482SIngo Molnar #include <linux/perf_event.h>
131da177e4SLinus Torvalds #include <linux/signal.h>
141da177e4SLinus Torvalds #include <linux/sched.h>
151da177e4SLinus Torvalds #include <linux/kernel.h>
161da177e4SLinus Torvalds #include <linux/errno.h>
171da177e4SLinus Torvalds #include <linux/string.h>
181da177e4SLinus Torvalds #include <linux/types.h>
191da177e4SLinus Torvalds #include <linux/ptrace.h>
201da177e4SLinus Torvalds #include <linux/mman.h>
211da177e4SLinus Torvalds #include <linux/mm.h>
227757591aSHeiko Carstens #include <linux/compat.h>
231da177e4SLinus Torvalds #include <linux/smp.h>
241eeb66a1SChristoph Hellwig #include <linux/kdebug.h>
251da177e4SLinus Torvalds #include <linux/init.h>
261da177e4SLinus Torvalds #include <linux/console.h>
271da177e4SLinus Torvalds #include <linux/module.h>
281da177e4SLinus Torvalds #include <linux/hardirq.h>
294ba069b8SMichael Grundy #include <linux/kprobes.h>
30be5ec363SMartin Schwidefsky #include <linux/uaccess.h>
3153492b1dSGerald Schaefer #include <linux/hugetlb.h>
32cbb870c8SHeiko Carstens #include <asm/asm-offsets.h>
331da177e4SLinus Torvalds #include <asm/pgtable.h>
34d7b250e2SHeiko Carstens #include <asm/irq.h>
356252d702SMartin Schwidefsky #include <asm/mmu_context.h>
36a0616cdeSDavid Howells #include <asm/facility.h>
37a806170eSHeiko Carstens #include "../kernel/entry.h"
381da177e4SLinus Torvalds 
39347a8dc3SMartin Schwidefsky #ifndef CONFIG_64BIT
401da177e4SLinus Torvalds #define __FAIL_ADDR_MASK 0x7ffff000
411da177e4SLinus Torvalds #define __SUBCODE_MASK 0x0200
421da177e4SLinus Torvalds #define __PF_RES_FIELD 0ULL
43347a8dc3SMartin Schwidefsky #else /* CONFIG_64BIT */
441da177e4SLinus Torvalds #define __FAIL_ADDR_MASK -4096L
451da177e4SLinus Torvalds #define __SUBCODE_MASK 0x0600
461da177e4SLinus Torvalds #define __PF_RES_FIELD 0x8000000000000000ULL
47347a8dc3SMartin Schwidefsky #endif /* CONFIG_64BIT */
481da177e4SLinus Torvalds 
4950d7280dSMartin Schwidefsky #define VM_FAULT_BADCONTEXT	0x010000
5050d7280dSMartin Schwidefsky #define VM_FAULT_BADMAP		0x020000
5150d7280dSMartin Schwidefsky #define VM_FAULT_BADACCESS	0x040000
52f2c76e3bSHeiko Carstens #define VM_FAULT_SIGNAL		0x080000
5324eb3a82SDominik Dingel #define VM_FAULT_PFAULT		0x100000
5450d7280dSMartin Schwidefsky 
55a4f32bdbSHeiko Carstens static unsigned long store_indication __read_mostly;
5692f842eaSMartin Schwidefsky 
57a4f32bdbSHeiko Carstens #ifdef CONFIG_64BIT
58a4f32bdbSHeiko Carstens static int __init fault_init(void)
5992f842eaSMartin Schwidefsky {
60a4f32bdbSHeiko Carstens 	if (test_facility(75))
6192f842eaSMartin Schwidefsky 		store_indication = 0xc00;
62a4f32bdbSHeiko Carstens 	return 0;
6392f842eaSMartin Schwidefsky }
64a4f32bdbSHeiko Carstens early_initcall(fault_init);
65a4f32bdbSHeiko Carstens #endif
6692f842eaSMartin Schwidefsky 
677ecb344aSMartin Schwidefsky static inline int notify_page_fault(struct pt_regs *regs)
6810c1031fSMartin Schwidefsky {
6933464e3bSChristoph Hellwig 	int ret = 0;
7033464e3bSChristoph Hellwig 
7133464e3bSChristoph Hellwig 	/* kprobe_running() needs smp_processor_id() */
7222e0a046SHeiko Carstens 	if (kprobes_built_in() && !user_mode(regs)) {
7333464e3bSChristoph Hellwig 		preempt_disable();
7433464e3bSChristoph Hellwig 		if (kprobe_running() && kprobe_fault_handler(regs, 14))
7533464e3bSChristoph Hellwig 			ret = 1;
7633464e3bSChristoph Hellwig 		preempt_enable();
7733464e3bSChristoph Hellwig 	}
7833464e3bSChristoph Hellwig 	return ret;
794ba069b8SMichael Grundy }
804ba069b8SMichael Grundy 
811da177e4SLinus Torvalds 
821da177e4SLinus Torvalds /*
831da177e4SLinus Torvalds  * Unlock any spinlocks which will prevent us from getting the
84cefc8be8SKirill Korotaev  * message out.
851da177e4SLinus Torvalds  */
861da177e4SLinus Torvalds void bust_spinlocks(int yes)
871da177e4SLinus Torvalds {
881da177e4SLinus Torvalds 	if (yes) {
891da177e4SLinus Torvalds 		oops_in_progress = 1;
901da177e4SLinus Torvalds 	} else {
911da177e4SLinus Torvalds 		int loglevel_save = console_loglevel;
921da177e4SLinus Torvalds 		console_unblank();
931da177e4SLinus Torvalds 		oops_in_progress = 0;
941da177e4SLinus Torvalds 		/*
951da177e4SLinus Torvalds 		 * OK, the message is on the console.  Now we call printk()
961da177e4SLinus Torvalds 		 * without oops_in_progress set so that printk will give klogd
971da177e4SLinus Torvalds 		 * a poke.  Hold onto your hats...
981da177e4SLinus Torvalds 		 */
991da177e4SLinus Torvalds 		console_loglevel = 15;
1001da177e4SLinus Torvalds 		printk(" ");
1011da177e4SLinus Torvalds 		console_loglevel = loglevel_save;
1021da177e4SLinus Torvalds 	}
1031da177e4SLinus Torvalds }
1041da177e4SLinus Torvalds 
1051da177e4SLinus Torvalds /*
106482b05ddSGerald Schaefer  * Returns the address space associated with the fault.
10761365e13SMartin Schwidefsky  * Returns 0 for kernel space and 1 for user space.
1081da177e4SLinus Torvalds  */
109457f2180SHeiko Carstens static inline int user_space_fault(struct pt_regs *regs)
1101da177e4SLinus Torvalds {
111457f2180SHeiko Carstens 	unsigned long trans_exc_code;
112457f2180SHeiko Carstens 
1131da177e4SLinus Torvalds 	/*
11461365e13SMartin Schwidefsky 	 * The lowest two bits of the translation exception
11561365e13SMartin Schwidefsky 	 * identification indicate which paging table was used.
1161da177e4SLinus Torvalds 	 */
117457f2180SHeiko Carstens 	trans_exc_code = regs->int_parm_long & 3;
118457f2180SHeiko Carstens 	if (trans_exc_code == 3) /* home space -> kernel */
119457f2180SHeiko Carstens 		return 0;
120457f2180SHeiko Carstens 	if (user_mode(regs))
121457f2180SHeiko Carstens 		return 1;
122457f2180SHeiko Carstens 	if (trans_exc_code == 2) /* secondary space -> set_fs */
12361365e13SMartin Schwidefsky 		return current->thread.mm_segment.ar4;
124457f2180SHeiko Carstens 	if (current->flags & PF_VCPU)
125457f2180SHeiko Carstens 		return 1;
126457f2180SHeiko Carstens 	return 0;
1271da177e4SLinus Torvalds }
1281da177e4SLinus Torvalds 
1293b7df342SHeiko Carstens static int bad_address(void *p)
1303b7df342SHeiko Carstens {
1313b7df342SHeiko Carstens 	unsigned long dummy;
1323b7df342SHeiko Carstens 
1333b7df342SHeiko Carstens 	return probe_kernel_address((unsigned long *)p, dummy);
1343b7df342SHeiko Carstens }
1353b7df342SHeiko Carstens 
1363b7df342SHeiko Carstens #ifdef CONFIG_64BIT
1373b7df342SHeiko Carstens static void dump_pagetable(unsigned long asce, unsigned long address)
1383b7df342SHeiko Carstens {
1393b7df342SHeiko Carstens 	unsigned long *table = __va(asce & PAGE_MASK);
1403b7df342SHeiko Carstens 
1413b7df342SHeiko Carstens 	pr_alert("AS:%016lx ", asce);
1423b7df342SHeiko Carstens 	switch (asce & _ASCE_TYPE_MASK) {
1433b7df342SHeiko Carstens 	case _ASCE_TYPE_REGION1:
1443b7df342SHeiko Carstens 		table = table + ((address >> 53) & 0x7ff);
1453b7df342SHeiko Carstens 		if (bad_address(table))
1463b7df342SHeiko Carstens 			goto bad;
1473b7df342SHeiko Carstens 		pr_cont("R1:%016lx ", *table);
1483b7df342SHeiko Carstens 		if (*table & _REGION_ENTRY_INVALID)
1493b7df342SHeiko Carstens 			goto out;
1503b7df342SHeiko Carstens 		table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
1513b7df342SHeiko Carstens 		/* fallthrough */
1523b7df342SHeiko Carstens 	case _ASCE_TYPE_REGION2:
1533b7df342SHeiko Carstens 		table = table + ((address >> 42) & 0x7ff);
1543b7df342SHeiko Carstens 		if (bad_address(table))
1553b7df342SHeiko Carstens 			goto bad;
1563b7df342SHeiko Carstens 		pr_cont("R2:%016lx ", *table);
1573b7df342SHeiko Carstens 		if (*table & _REGION_ENTRY_INVALID)
1583b7df342SHeiko Carstens 			goto out;
1593b7df342SHeiko Carstens 		table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
1603b7df342SHeiko Carstens 		/* fallthrough */
1613b7df342SHeiko Carstens 	case _ASCE_TYPE_REGION3:
1623b7df342SHeiko Carstens 		table = table + ((address >> 31) & 0x7ff);
1633b7df342SHeiko Carstens 		if (bad_address(table))
1643b7df342SHeiko Carstens 			goto bad;
1653b7df342SHeiko Carstens 		pr_cont("R3:%016lx ", *table);
1663b7df342SHeiko Carstens 		if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
1673b7df342SHeiko Carstens 			goto out;
1683b7df342SHeiko Carstens 		table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
1693b7df342SHeiko Carstens 		/* fallthrough */
1703b7df342SHeiko Carstens 	case _ASCE_TYPE_SEGMENT:
1713b7df342SHeiko Carstens 		table = table + ((address >> 20) & 0x7ff);
1723b7df342SHeiko Carstens 		if (bad_address(table))
1733b7df342SHeiko Carstens 			goto bad;
17491c0837eSJoe Perches 		pr_cont("S:%016lx ", *table);
1753b7df342SHeiko Carstens 		if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
1763b7df342SHeiko Carstens 			goto out;
1773b7df342SHeiko Carstens 		table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
1783b7df342SHeiko Carstens 	}
1793b7df342SHeiko Carstens 	table = table + ((address >> 12) & 0xff);
1803b7df342SHeiko Carstens 	if (bad_address(table))
1813b7df342SHeiko Carstens 		goto bad;
1823b7df342SHeiko Carstens 	pr_cont("P:%016lx ", *table);
1833b7df342SHeiko Carstens out:
1843b7df342SHeiko Carstens 	pr_cont("\n");
1853b7df342SHeiko Carstens 	return;
1863b7df342SHeiko Carstens bad:
1873b7df342SHeiko Carstens 	pr_cont("BAD\n");
1883b7df342SHeiko Carstens }
1893b7df342SHeiko Carstens 
1903b7df342SHeiko Carstens #else /* CONFIG_64BIT */
1913b7df342SHeiko Carstens 
1923b7df342SHeiko Carstens static void dump_pagetable(unsigned long asce, unsigned long address)
1933b7df342SHeiko Carstens {
1943b7df342SHeiko Carstens 	unsigned long *table = __va(asce & PAGE_MASK);
1953b7df342SHeiko Carstens 
1963b7df342SHeiko Carstens 	pr_alert("AS:%08lx ", asce);
1973b7df342SHeiko Carstens 	table = table + ((address >> 20) & 0x7ff);
1983b7df342SHeiko Carstens 	if (bad_address(table))
1993b7df342SHeiko Carstens 		goto bad;
2003b7df342SHeiko Carstens 	pr_cont("S:%08lx ", *table);
2013b7df342SHeiko Carstens 	if (*table & _SEGMENT_ENTRY_INVALID)
2023b7df342SHeiko Carstens 		goto out;
2033b7df342SHeiko Carstens 	table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
2043b7df342SHeiko Carstens 	table = table + ((address >> 12) & 0xff);
2053b7df342SHeiko Carstens 	if (bad_address(table))
2063b7df342SHeiko Carstens 		goto bad;
2073b7df342SHeiko Carstens 	pr_cont("P:%08lx ", *table);
2083b7df342SHeiko Carstens out:
2093b7df342SHeiko Carstens 	pr_cont("\n");
2103b7df342SHeiko Carstens 	return;
2113b7df342SHeiko Carstens bad:
2123b7df342SHeiko Carstens 	pr_cont("BAD\n");
2133b7df342SHeiko Carstens }
2143b7df342SHeiko Carstens 
2153b7df342SHeiko Carstens #endif /* CONFIG_64BIT */
2163b7df342SHeiko Carstens 
2173b7df342SHeiko Carstens static void dump_fault_info(struct pt_regs *regs)
2183b7df342SHeiko Carstens {
2193b7df342SHeiko Carstens 	unsigned long asce;
2203b7df342SHeiko Carstens 
2213b7df342SHeiko Carstens 	pr_alert("Fault in ");
2223b7df342SHeiko Carstens 	switch (regs->int_parm_long & 3) {
2233b7df342SHeiko Carstens 	case 3:
2243b7df342SHeiko Carstens 		pr_cont("home space ");
2253b7df342SHeiko Carstens 		break;
2263b7df342SHeiko Carstens 	case 2:
2273b7df342SHeiko Carstens 		pr_cont("secondary space ");
2283b7df342SHeiko Carstens 		break;
2293b7df342SHeiko Carstens 	case 1:
2303b7df342SHeiko Carstens 		pr_cont("access register ");
2313b7df342SHeiko Carstens 		break;
2323b7df342SHeiko Carstens 	case 0:
2333b7df342SHeiko Carstens 		pr_cont("primary space ");
2343b7df342SHeiko Carstens 		break;
2353b7df342SHeiko Carstens 	}
2363b7df342SHeiko Carstens 	pr_cont("mode while using ");
2373b7df342SHeiko Carstens 	if (!user_space_fault(regs)) {
2383b7df342SHeiko Carstens 		asce = S390_lowcore.kernel_asce;
2393b7df342SHeiko Carstens 		pr_cont("kernel ");
2403b7df342SHeiko Carstens 	}
2413b7df342SHeiko Carstens #ifdef CONFIG_PGSTE
2423b7df342SHeiko Carstens 	else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
2433b7df342SHeiko Carstens 		struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
2443b7df342SHeiko Carstens 		asce = gmap->asce;
2453b7df342SHeiko Carstens 		pr_cont("gmap ");
2463b7df342SHeiko Carstens 	}
2473b7df342SHeiko Carstens #endif
2483b7df342SHeiko Carstens 	else {
2493b7df342SHeiko Carstens 		asce = S390_lowcore.user_asce;
2503b7df342SHeiko Carstens 		pr_cont("user ");
2513b7df342SHeiko Carstens 	}
2523b7df342SHeiko Carstens 	pr_cont("ASCE.\n");
2533b7df342SHeiko Carstens 	dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
2543b7df342SHeiko Carstens }
2553b7df342SHeiko Carstens 
256aa33c8cbSMartin Schwidefsky static inline void report_user_fault(struct pt_regs *regs, long signr)
257ab3c68eeSHeiko Carstens {
258ab3c68eeSHeiko Carstens 	if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
259ab3c68eeSHeiko Carstens 		return;
260ab3c68eeSHeiko Carstens 	if (!unhandled_signal(current, signr))
261ab3c68eeSHeiko Carstens 		return;
262ab3c68eeSHeiko Carstens 	if (!printk_ratelimit())
263ab3c68eeSHeiko Carstens 		return;
264413d4047SHeiko Carstens 	printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d",
265413d4047SHeiko Carstens 	       regs->int_code & 0xffff, regs->int_code >> 17);
266ab3c68eeSHeiko Carstens 	print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
267aa33c8cbSMartin Schwidefsky 	printk(KERN_CONT "\n");
2683b7df342SHeiko Carstens 	printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
2693b7df342SHeiko Carstens 	       regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
2703b7df342SHeiko Carstens 	dump_fault_info(regs);
271ab3c68eeSHeiko Carstens 	show_regs(regs);
272ab3c68eeSHeiko Carstens }
273ab3c68eeSHeiko Carstens 
2741da177e4SLinus Torvalds /*
2751da177e4SLinus Torvalds  * Send SIGSEGV to task.  This is an external routine
2761da177e4SLinus Torvalds  * to keep the stack usage of do_page_fault small.
2771da177e4SLinus Torvalds  */
278aa33c8cbSMartin Schwidefsky static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
2791da177e4SLinus Torvalds {
2801da177e4SLinus Torvalds 	struct siginfo si;
2811da177e4SLinus Torvalds 
282aa33c8cbSMartin Schwidefsky 	report_user_fault(regs, SIGSEGV);
2831da177e4SLinus Torvalds 	si.si_signo = SIGSEGV;
2841da177e4SLinus Torvalds 	si.si_code = si_code;
285aa33c8cbSMartin Schwidefsky 	si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
2861da177e4SLinus Torvalds 	force_sig_info(SIGSEGV, &si, current);
2871da177e4SLinus Torvalds }
2881da177e4SLinus Torvalds 
289aa33c8cbSMartin Schwidefsky static noinline void do_no_context(struct pt_regs *regs)
29010c1031fSMartin Schwidefsky {
29110c1031fSMartin Schwidefsky 	const struct exception_table_entry *fixup;
29261365e13SMartin Schwidefsky 	unsigned long address;
29310c1031fSMartin Schwidefsky 
29410c1031fSMartin Schwidefsky 	/* Are we prepared to handle this kernel fault?  */
29550d7280dSMartin Schwidefsky 	fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
29610c1031fSMartin Schwidefsky 	if (fixup) {
297eb608fb3SHeiko Carstens 		regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
29810c1031fSMartin Schwidefsky 		return;
29910c1031fSMartin Schwidefsky 	}
30010c1031fSMartin Schwidefsky 
30110c1031fSMartin Schwidefsky 	/*
30210c1031fSMartin Schwidefsky 	 * Oops. The kernel tried to access some bad page. We'll have to
30310c1031fSMartin Schwidefsky 	 * terminate things with extreme prejudice.
30410c1031fSMartin Schwidefsky 	 */
305aa33c8cbSMartin Schwidefsky 	address = regs->int_parm_long & __FAIL_ADDR_MASK;
306457f2180SHeiko Carstens 	if (!user_space_fault(regs))
30710c1031fSMartin Schwidefsky 		printk(KERN_ALERT "Unable to handle kernel pointer dereference"
3083b7df342SHeiko Carstens 		       " in virtual kernel address space\n");
30910c1031fSMartin Schwidefsky 	else
31010c1031fSMartin Schwidefsky 		printk(KERN_ALERT "Unable to handle kernel paging request"
3113b7df342SHeiko Carstens 		       " in virtual user address space\n");
3123b7df342SHeiko Carstens 	printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
3133b7df342SHeiko Carstens 	       regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
3143b7df342SHeiko Carstens 	dump_fault_info(regs);
315aa33c8cbSMartin Schwidefsky 	die(regs, "Oops");
31610c1031fSMartin Schwidefsky 	do_exit(SIGKILL);
31710c1031fSMartin Schwidefsky }
31810c1031fSMartin Schwidefsky 
319aa33c8cbSMartin Schwidefsky static noinline void do_low_address(struct pt_regs *regs)
32010c1031fSMartin Schwidefsky {
32110c1031fSMartin Schwidefsky 	/* Low-address protection hit in kernel mode means
32210c1031fSMartin Schwidefsky 	   NULL pointer write access in kernel mode.  */
32310c1031fSMartin Schwidefsky 	if (regs->psw.mask & PSW_MASK_PSTATE) {
32410c1031fSMartin Schwidefsky 		/* Low-address protection hit in user mode 'cannot happen'. */
325aa33c8cbSMartin Schwidefsky 		die (regs, "Low-address protection");
32610c1031fSMartin Schwidefsky 		do_exit(SIGKILL);
32710c1031fSMartin Schwidefsky 	}
32810c1031fSMartin Schwidefsky 
329aa33c8cbSMartin Schwidefsky 	do_no_context(regs);
33010c1031fSMartin Schwidefsky }
33110c1031fSMartin Schwidefsky 
332aa33c8cbSMartin Schwidefsky static noinline void do_sigbus(struct pt_regs *regs)
33310c1031fSMartin Schwidefsky {
33410c1031fSMartin Schwidefsky 	struct task_struct *tsk = current;
33536bf9680SMartin Schwidefsky 	struct siginfo si;
33610c1031fSMartin Schwidefsky 
33710c1031fSMartin Schwidefsky 	/*
33810c1031fSMartin Schwidefsky 	 * Send a sigbus, regardless of whether we were in kernel
33910c1031fSMartin Schwidefsky 	 * or user mode.
34010c1031fSMartin Schwidefsky 	 */
34136bf9680SMartin Schwidefsky 	si.si_signo = SIGBUS;
34236bf9680SMartin Schwidefsky 	si.si_errno = 0;
34336bf9680SMartin Schwidefsky 	si.si_code = BUS_ADRERR;
344aa33c8cbSMartin Schwidefsky 	si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
34536bf9680SMartin Schwidefsky 	force_sig_info(SIGBUS, &si, tsk);
34610c1031fSMartin Schwidefsky }
34710c1031fSMartin Schwidefsky 
348aa33c8cbSMartin Schwidefsky static noinline void do_fault_error(struct pt_regs *regs, int fault)
34950d7280dSMartin Schwidefsky {
35050d7280dSMartin Schwidefsky 	int si_code;
35150d7280dSMartin Schwidefsky 
35250d7280dSMartin Schwidefsky 	switch (fault) {
35350d7280dSMartin Schwidefsky 	case VM_FAULT_BADACCESS:
35450d7280dSMartin Schwidefsky 	case VM_FAULT_BADMAP:
35550d7280dSMartin Schwidefsky 		/* Bad memory access. Check if it is kernel or user space. */
3567d256175SHeiko Carstens 		if (user_mode(regs)) {
35750d7280dSMartin Schwidefsky 			/* User mode accesses just cause a SIGSEGV */
35850d7280dSMartin Schwidefsky 			si_code = (fault == VM_FAULT_BADMAP) ?
35950d7280dSMartin Schwidefsky 				SEGV_MAPERR : SEGV_ACCERR;
360aa33c8cbSMartin Schwidefsky 			do_sigsegv(regs, si_code);
36150d7280dSMartin Schwidefsky 			return;
36250d7280dSMartin Schwidefsky 		}
36350d7280dSMartin Schwidefsky 	case VM_FAULT_BADCONTEXT:
36424eb3a82SDominik Dingel 	case VM_FAULT_PFAULT:
365aa33c8cbSMartin Schwidefsky 		do_no_context(regs);
36650d7280dSMartin Schwidefsky 		break;
367f2c76e3bSHeiko Carstens 	case VM_FAULT_SIGNAL:
368f2c76e3bSHeiko Carstens 		if (!user_mode(regs))
369f2c76e3bSHeiko Carstens 			do_no_context(regs);
370f2c76e3bSHeiko Carstens 		break;
37150d7280dSMartin Schwidefsky 	default: /* fault & VM_FAULT_ERROR */
37299583181SHeiko Carstens 		if (fault & VM_FAULT_OOM) {
3737d256175SHeiko Carstens 			if (!user_mode(regs))
374aa33c8cbSMartin Schwidefsky 				do_no_context(regs);
37599583181SHeiko Carstens 			else
37650d7280dSMartin Schwidefsky 				pagefault_out_of_memory();
37799583181SHeiko Carstens 		} else if (fault & VM_FAULT_SIGBUS) {
37850d7280dSMartin Schwidefsky 			/* Kernel mode? Handle exceptions or die */
3797d256175SHeiko Carstens 			if (!user_mode(regs))
380aa33c8cbSMartin Schwidefsky 				do_no_context(regs);
38136bf9680SMartin Schwidefsky 			else
382aa33c8cbSMartin Schwidefsky 				do_sigbus(regs);
38350d7280dSMartin Schwidefsky 		} else
38450d7280dSMartin Schwidefsky 			BUG();
38550d7280dSMartin Schwidefsky 		break;
38650d7280dSMartin Schwidefsky 	}
38750d7280dSMartin Schwidefsky }
38850d7280dSMartin Schwidefsky 
3891da177e4SLinus Torvalds /*
3901da177e4SLinus Torvalds  * This routine handles page faults.  It determines the address,
3911da177e4SLinus Torvalds  * and the problem, and then passes it off to one of the appropriate
3921da177e4SLinus Torvalds  * routines.
3931da177e4SLinus Torvalds  *
39450d7280dSMartin Schwidefsky  * interruption code (int_code):
3951da177e4SLinus Torvalds  *   04       Protection           ->  Write-Protection  (suprression)
3961da177e4SLinus Torvalds  *   10       Segment translation  ->  Not present       (nullification)
3971da177e4SLinus Torvalds  *   11       Page translation     ->  Not present       (nullification)
3981da177e4SLinus Torvalds  *   3b       Region third trans.  ->  Not present       (nullification)
3991da177e4SLinus Torvalds  */
400aa33c8cbSMartin Schwidefsky static inline int do_exception(struct pt_regs *regs, int access)
4011da177e4SLinus Torvalds {
40224eb3a82SDominik Dingel #ifdef CONFIG_PGSTE
40324eb3a82SDominik Dingel 	struct gmap *gmap;
40424eb3a82SDominik Dingel #endif
4051da177e4SLinus Torvalds 	struct task_struct *tsk;
4061da177e4SLinus Torvalds 	struct mm_struct *mm;
4071da177e4SLinus Torvalds 	struct vm_area_struct *vma;
408aa33c8cbSMartin Schwidefsky 	unsigned long trans_exc_code;
4091da177e4SLinus Torvalds 	unsigned long address;
41033ce6140SHeiko Carstens 	unsigned int flags;
41133ce6140SHeiko Carstens 	int fault;
41210c1031fSMartin Schwidefsky 
41339efd4ecSMartin Schwidefsky 	tsk = current;
41439efd4ecSMartin Schwidefsky 	/*
41539efd4ecSMartin Schwidefsky 	 * The instruction that caused the program check has
41639efd4ecSMartin Schwidefsky 	 * been nullified. Don't signal single step via SIGTRAP.
41739efd4ecSMartin Schwidefsky 	 */
418d3a73acbSMartin Schwidefsky 	clear_pt_regs_flag(regs, PIF_PER_TRAP);
41939efd4ecSMartin Schwidefsky 
4207ecb344aSMartin Schwidefsky 	if (notify_page_fault(regs))
42150d7280dSMartin Schwidefsky 		return 0;
4221da177e4SLinus Torvalds 
4231da177e4SLinus Torvalds 	mm = tsk->mm;
424aa33c8cbSMartin Schwidefsky 	trans_exc_code = regs->int_parm_long;
4251da177e4SLinus Torvalds 
4261da177e4SLinus Torvalds 	/*
4271da177e4SLinus Torvalds 	 * Verify that the fault happened in user space, that
4281da177e4SLinus Torvalds 	 * we are not in an interrupt and that there is a
4291da177e4SLinus Torvalds 	 * user context.
4301da177e4SLinus Torvalds 	 */
43150d7280dSMartin Schwidefsky 	fault = VM_FAULT_BADCONTEXT;
432457f2180SHeiko Carstens 	if (unlikely(!user_space_fault(regs) || in_atomic() || !mm))
43350d7280dSMartin Schwidefsky 		goto out;
4341da177e4SLinus Torvalds 
43561365e13SMartin Schwidefsky 	address = trans_exc_code & __FAIL_ADDR_MASK;
436a8b0ca17SPeter Zijlstra 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
437f2c76e3bSHeiko Carstens 	flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
438759496baSJohannes Weiner 	if (user_mode(regs))
439759496baSJohannes Weiner 		flags |= FAULT_FLAG_USER;
44033ce6140SHeiko Carstens 	if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
44133ce6140SHeiko Carstens 		flags |= FAULT_FLAG_WRITE;
4421da177e4SLinus Torvalds 	down_read(&mm->mmap_sem);
4431da177e4SLinus Torvalds 
444e5992f2eSMartin Schwidefsky #ifdef CONFIG_PGSTE
445527e30b4SMartin Schwidefsky 	gmap = (current->flags & PF_VCPU) ?
446527e30b4SMartin Schwidefsky 		(struct gmap *) S390_lowcore.gmap : NULL;
44724eb3a82SDominik Dingel 	if (gmap) {
448527e30b4SMartin Schwidefsky 		current->thread.gmap_addr = address;
449527e30b4SMartin Schwidefsky 		address = __gmap_translate(gmap, address);
450e5992f2eSMartin Schwidefsky 		if (address == -EFAULT) {
451e5992f2eSMartin Schwidefsky 			fault = VM_FAULT_BADMAP;
452e5992f2eSMartin Schwidefsky 			goto out_up;
453e5992f2eSMartin Schwidefsky 		}
45424eb3a82SDominik Dingel 		if (gmap->pfault_enabled)
45524eb3a82SDominik Dingel 			flags |= FAULT_FLAG_RETRY_NOWAIT;
456e5992f2eSMartin Schwidefsky 	}
457e5992f2eSMartin Schwidefsky #endif
458e5992f2eSMartin Schwidefsky 
459e5992f2eSMartin Schwidefsky retry:
46050d7280dSMartin Schwidefsky 	fault = VM_FAULT_BADMAP;
4611da177e4SLinus Torvalds 	vma = find_vma(mm, address);
4621da177e4SLinus Torvalds 	if (!vma)
46350d7280dSMartin Schwidefsky 		goto out_up;
464c1821c2eSGerald Schaefer 
46550d7280dSMartin Schwidefsky 	if (unlikely(vma->vm_start > address)) {
4661da177e4SLinus Torvalds 		if (!(vma->vm_flags & VM_GROWSDOWN))
46750d7280dSMartin Schwidefsky 			goto out_up;
4681da177e4SLinus Torvalds 		if (expand_stack(vma, address))
46950d7280dSMartin Schwidefsky 			goto out_up;
47050d7280dSMartin Schwidefsky 	}
47150d7280dSMartin Schwidefsky 
4721da177e4SLinus Torvalds 	/*
4731da177e4SLinus Torvalds 	 * Ok, we have a good vm_area for this memory access, so
4741da177e4SLinus Torvalds 	 * we can handle it..
4751da177e4SLinus Torvalds 	 */
47650d7280dSMartin Schwidefsky 	fault = VM_FAULT_BADACCESS;
4771ab947deSMartin Schwidefsky 	if (unlikely(!(vma->vm_flags & access)))
47850d7280dSMartin Schwidefsky 		goto out_up;
4791da177e4SLinus Torvalds 
48053492b1dSGerald Schaefer 	if (is_vm_hugetlb_page(vma))
48153492b1dSGerald Schaefer 		address &= HPAGE_MASK;
4821da177e4SLinus Torvalds 	/*
4831da177e4SLinus Torvalds 	 * If for any reason at all we couldn't handle the fault,
4841da177e4SLinus Torvalds 	 * make sure we exit gracefully rather than endlessly redo
4851da177e4SLinus Torvalds 	 * the fault.
4861da177e4SLinus Torvalds 	 */
48733ce6140SHeiko Carstens 	fault = handle_mm_fault(mm, vma, address, flags);
488f2c76e3bSHeiko Carstens 	/* No reason to continue if interrupted by SIGKILL. */
489f2c76e3bSHeiko Carstens 	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
490f2c76e3bSHeiko Carstens 		fault = VM_FAULT_SIGNAL;
491f2c76e3bSHeiko Carstens 		goto out;
492f2c76e3bSHeiko Carstens 	}
49350d7280dSMartin Schwidefsky 	if (unlikely(fault & VM_FAULT_ERROR))
49450d7280dSMartin Schwidefsky 		goto out_up;
49550d7280dSMartin Schwidefsky 
49633ce6140SHeiko Carstens 	/*
49733ce6140SHeiko Carstens 	 * Major/minor page fault accounting is only done on the
49833ce6140SHeiko Carstens 	 * initial attempt. If we go through a retry, it is extremely
49933ce6140SHeiko Carstens 	 * likely that the page will be found in page cache at that point.
50033ce6140SHeiko Carstens 	 */
50133ce6140SHeiko Carstens 	if (flags & FAULT_FLAG_ALLOW_RETRY) {
502bde69af2SHeiko Carstens 		if (fault & VM_FAULT_MAJOR) {
50383c54070SNick Piggin 			tsk->maj_flt++;
504a8b0ca17SPeter Zijlstra 			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
505bde69af2SHeiko Carstens 				      regs, address);
506bde69af2SHeiko Carstens 		} else {
50783c54070SNick Piggin 			tsk->min_flt++;
508a8b0ca17SPeter Zijlstra 			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
509bde69af2SHeiko Carstens 				      regs, address);
510bde69af2SHeiko Carstens 		}
51133ce6140SHeiko Carstens 		if (fault & VM_FAULT_RETRY) {
51224eb3a82SDominik Dingel #ifdef CONFIG_PGSTE
51324eb3a82SDominik Dingel 			if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
51424eb3a82SDominik Dingel 				/* FAULT_FLAG_RETRY_NOWAIT has been set,
51524eb3a82SDominik Dingel 				 * mmap_sem has not been released */
51624eb3a82SDominik Dingel 				current->thread.gmap_pfault = 1;
51724eb3a82SDominik Dingel 				fault = VM_FAULT_PFAULT;
51824eb3a82SDominik Dingel 				goto out_up;
51924eb3a82SDominik Dingel 			}
52024eb3a82SDominik Dingel #endif
52133ce6140SHeiko Carstens 			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
52233ce6140SHeiko Carstens 			 * of starvation. */
52324eb3a82SDominik Dingel 			flags &= ~(FAULT_FLAG_ALLOW_RETRY |
52424eb3a82SDominik Dingel 				   FAULT_FLAG_RETRY_NOWAIT);
52545cac65bSShaohua Li 			flags |= FAULT_FLAG_TRIED;
526e5992f2eSMartin Schwidefsky 			down_read(&mm->mmap_sem);
52733ce6140SHeiko Carstens 			goto retry;
52833ce6140SHeiko Carstens 		}
52933ce6140SHeiko Carstens 	}
530527e30b4SMartin Schwidefsky #ifdef CONFIG_PGSTE
531527e30b4SMartin Schwidefsky 	if (gmap) {
532527e30b4SMartin Schwidefsky 		address =  __gmap_link(gmap, current->thread.gmap_addr,
533527e30b4SMartin Schwidefsky 				       address);
534527e30b4SMartin Schwidefsky 		if (address == -EFAULT) {
535527e30b4SMartin Schwidefsky 			fault = VM_FAULT_BADMAP;
536527e30b4SMartin Schwidefsky 			goto out_up;
537527e30b4SMartin Schwidefsky 		}
538527e30b4SMartin Schwidefsky 		if (address == -ENOMEM) {
539527e30b4SMartin Schwidefsky 			fault = VM_FAULT_OOM;
540527e30b4SMartin Schwidefsky 			goto out_up;
541527e30b4SMartin Schwidefsky 		}
542527e30b4SMartin Schwidefsky 	}
543527e30b4SMartin Schwidefsky #endif
54450d7280dSMartin Schwidefsky 	fault = 0;
54550d7280dSMartin Schwidefsky out_up:
5461da177e4SLinus Torvalds 	up_read(&mm->mmap_sem);
54750d7280dSMartin Schwidefsky out:
54850d7280dSMartin Schwidefsky 	return fault;
5491da177e4SLinus Torvalds }
5501da177e4SLinus Torvalds 
5517a5388deSHeiko Carstens void do_protection_exception(struct pt_regs *regs)
5521da177e4SLinus Torvalds {
553aa33c8cbSMartin Schwidefsky 	unsigned long trans_exc_code;
55450d7280dSMartin Schwidefsky 	int fault;
55561365e13SMartin Schwidefsky 
556aa33c8cbSMartin Schwidefsky 	trans_exc_code = regs->int_parm_long;
557f752ac4dSMartin Schwidefsky 	/*
558f752ac4dSMartin Schwidefsky 	 * Protection exceptions are suppressing, decrement psw address.
559f752ac4dSMartin Schwidefsky 	 * The exception to this rule are aborted transactions, for these
560f752ac4dSMartin Schwidefsky 	 * the PSW already points to the correct location.
561f752ac4dSMartin Schwidefsky 	 */
562f752ac4dSMartin Schwidefsky 	if (!(regs->int_code & 0x200))
563aa33c8cbSMartin Schwidefsky 		regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
56410c1031fSMartin Schwidefsky 	/*
56510c1031fSMartin Schwidefsky 	 * Check for low-address protection.  This needs to be treated
56610c1031fSMartin Schwidefsky 	 * as a special case because the translation exception code
56710c1031fSMartin Schwidefsky 	 * field is not guaranteed to contain valid data in this case.
56810c1031fSMartin Schwidefsky 	 */
56961365e13SMartin Schwidefsky 	if (unlikely(!(trans_exc_code & 4))) {
570aa33c8cbSMartin Schwidefsky 		do_low_address(regs);
57110c1031fSMartin Schwidefsky 		return;
57210c1031fSMartin Schwidefsky 	}
573aa33c8cbSMartin Schwidefsky 	fault = do_exception(regs, VM_WRITE);
57450d7280dSMartin Schwidefsky 	if (unlikely(fault))
575aa33c8cbSMartin Schwidefsky 		do_fault_error(regs, fault);
5761da177e4SLinus Torvalds }
5777a5388deSHeiko Carstens NOKPROBE_SYMBOL(do_protection_exception);
5781da177e4SLinus Torvalds 
5797a5388deSHeiko Carstens void do_dat_exception(struct pt_regs *regs)
5801da177e4SLinus Torvalds {
5811ab947deSMartin Schwidefsky 	int access, fault;
58250d7280dSMartin Schwidefsky 
5831ab947deSMartin Schwidefsky 	access = VM_READ | VM_EXEC | VM_WRITE;
584aa33c8cbSMartin Schwidefsky 	fault = do_exception(regs, access);
58550d7280dSMartin Schwidefsky 	if (unlikely(fault))
586aa33c8cbSMartin Schwidefsky 		do_fault_error(regs, fault);
5871da177e4SLinus Torvalds }
5887a5388deSHeiko Carstens NOKPROBE_SYMBOL(do_dat_exception);
5891da177e4SLinus Torvalds 
5901da177e4SLinus Torvalds #ifdef CONFIG_PFAULT
5911da177e4SLinus Torvalds /*
5921da177e4SLinus Torvalds  * 'pfault' pseudo page faults routines.
5931da177e4SLinus Torvalds  */
594fb0a9d7eSHeiko Carstens static int pfault_disable;
5951da177e4SLinus Torvalds 
5961da177e4SLinus Torvalds static int __init nopfault(char *str)
5971da177e4SLinus Torvalds {
5981da177e4SLinus Torvalds 	pfault_disable = 1;
5991da177e4SLinus Torvalds 	return 1;
6001da177e4SLinus Torvalds }
6011da177e4SLinus Torvalds 
6021da177e4SLinus Torvalds __setup("nopfault", nopfault);
6031da177e4SLinus Torvalds 
6047dd8fe1fSHeiko Carstens struct pfault_refbk {
6057dd8fe1fSHeiko Carstens 	u16 refdiagc;
6067dd8fe1fSHeiko Carstens 	u16 reffcode;
6077dd8fe1fSHeiko Carstens 	u16 refdwlen;
6087dd8fe1fSHeiko Carstens 	u16 refversn;
6097dd8fe1fSHeiko Carstens 	u64 refgaddr;
6107dd8fe1fSHeiko Carstens 	u64 refselmk;
6117dd8fe1fSHeiko Carstens 	u64 refcmpmk;
6127dd8fe1fSHeiko Carstens 	u64 reserved;
6137dd8fe1fSHeiko Carstens } __attribute__ ((packed, aligned(8)));
6141da177e4SLinus Torvalds 
6151da177e4SLinus Torvalds int pfault_init(void)
6161da177e4SLinus Torvalds {
6177dd8fe1fSHeiko Carstens 	struct pfault_refbk refbk = {
6187dd8fe1fSHeiko Carstens 		.refdiagc = 0x258,
6197dd8fe1fSHeiko Carstens 		.reffcode = 0,
6207dd8fe1fSHeiko Carstens 		.refdwlen = 5,
6217dd8fe1fSHeiko Carstens 		.refversn = 2,
6227dd8fe1fSHeiko Carstens 		.refgaddr = __LC_CURRENT_PID,
6237dd8fe1fSHeiko Carstens 		.refselmk = 1ULL << 48,
6247dd8fe1fSHeiko Carstens 		.refcmpmk = 1ULL << 48,
6257dd8fe1fSHeiko Carstens 		.reserved = __PF_RES_FIELD };
6261da177e4SLinus Torvalds         int rc;
6271da177e4SLinus Torvalds 
628f32269a0SCarsten Otte 	if (pfault_disable)
6291da177e4SLinus Torvalds 		return -1;
63094c12cc7SMartin Schwidefsky 	asm volatile(
6311da177e4SLinus Torvalds 		"	diag	%1,%0,0x258\n"
6321da177e4SLinus Torvalds 		"0:	j	2f\n"
6331da177e4SLinus Torvalds 		"1:	la	%0,8\n"
6341da177e4SLinus Torvalds 		"2:\n"
63594c12cc7SMartin Schwidefsky 		EX_TABLE(0b,1b)
636d4b68996SMartin Schwidefsky 		: "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
6371da177e4SLinus Torvalds         return rc;
6381da177e4SLinus Torvalds }
6391da177e4SLinus Torvalds 
6401da177e4SLinus Torvalds void pfault_fini(void)
6411da177e4SLinus Torvalds {
6427dd8fe1fSHeiko Carstens 	struct pfault_refbk refbk = {
6437dd8fe1fSHeiko Carstens 		.refdiagc = 0x258,
6447dd8fe1fSHeiko Carstens 		.reffcode = 1,
6457dd8fe1fSHeiko Carstens 		.refdwlen = 5,
6467dd8fe1fSHeiko Carstens 		.refversn = 2,
6477dd8fe1fSHeiko Carstens 	};
6481da177e4SLinus Torvalds 
649f32269a0SCarsten Otte 	if (pfault_disable)
6501da177e4SLinus Torvalds 		return;
65194c12cc7SMartin Schwidefsky 	asm volatile(
6521da177e4SLinus Torvalds 		"	diag	%0,0,0x258\n"
6531da177e4SLinus Torvalds 		"0:\n"
65494c12cc7SMartin Schwidefsky 		EX_TABLE(0b,0b)
655d4b68996SMartin Schwidefsky 		: : "a" (&refbk), "m" (refbk) : "cc");
6561da177e4SLinus Torvalds }
6571da177e4SLinus Torvalds 
658f2db2e6cSHeiko Carstens static DEFINE_SPINLOCK(pfault_lock);
659f2db2e6cSHeiko Carstens static LIST_HEAD(pfault_list);
660f2db2e6cSHeiko Carstens 
661fde15c3aSHeiko Carstens static void pfault_interrupt(struct ext_code ext_code,
662f6649a7eSMartin Schwidefsky 			     unsigned int param32, unsigned long param64)
6631da177e4SLinus Torvalds {
6641da177e4SLinus Torvalds 	struct task_struct *tsk;
6651da177e4SLinus Torvalds 	__u16 subcode;
666f2db2e6cSHeiko Carstens 	pid_t pid;
6671da177e4SLinus Torvalds 
6681da177e4SLinus Torvalds 	/*
6691da177e4SLinus Torvalds 	 * Get the external interruption subcode & pfault
6701da177e4SLinus Torvalds 	 * initial/completion signal bit. VM stores this
6711da177e4SLinus Torvalds 	 * in the 'cpu address' field associated with the
6721da177e4SLinus Torvalds          * external interrupt.
6731da177e4SLinus Torvalds 	 */
674fde15c3aSHeiko Carstens 	subcode = ext_code.subcode;
6751da177e4SLinus Torvalds 	if ((subcode & 0xff00) != __SUBCODE_MASK)
6761da177e4SLinus Torvalds 		return;
677420f42ecSHeiko Carstens 	inc_irq_stat(IRQEXT_PFL);
678f2db2e6cSHeiko Carstens 	/* Get the token (= pid of the affected task). */
679f2db2e6cSHeiko Carstens 	pid = sizeof(void *) == 4 ? param32 : param64;
680f2db2e6cSHeiko Carstens 	rcu_read_lock();
681f2db2e6cSHeiko Carstens 	tsk = find_task_by_pid_ns(pid, &init_pid_ns);
682f2db2e6cSHeiko Carstens 	if (tsk)
683f2db2e6cSHeiko Carstens 		get_task_struct(tsk);
684f2db2e6cSHeiko Carstens 	rcu_read_unlock();
685f2db2e6cSHeiko Carstens 	if (!tsk)
686f2db2e6cSHeiko Carstens 		return;
687f2db2e6cSHeiko Carstens 	spin_lock(&pfault_lock);
6881da177e4SLinus Torvalds 	if (subcode & 0x0080) {
6891da177e4SLinus Torvalds 		/* signal bit is set -> a page has been swapped in by VM */
690f2db2e6cSHeiko Carstens 		if (tsk->thread.pfault_wait == 1) {
6911da177e4SLinus Torvalds 			/* Initial interrupt was faster than the completion
6921da177e4SLinus Torvalds 			 * interrupt. pfault_wait is valid. Set pfault_wait
6931da177e4SLinus Torvalds 			 * back to zero and wake up the process. This can
6941da177e4SLinus Torvalds 			 * safely be done because the task is still sleeping
695b6d09449SMartin Schwidefsky 			 * and can't produce new pfaults. */
6961da177e4SLinus Torvalds 			tsk->thread.pfault_wait = 0;
697f2db2e6cSHeiko Carstens 			list_del(&tsk->thread.list);
6981da177e4SLinus Torvalds 			wake_up_process(tsk);
699d5e50a51SHeiko Carstens 			put_task_struct(tsk);
700f2db2e6cSHeiko Carstens 		} else {
701f2db2e6cSHeiko Carstens 			/* Completion interrupt was faster than initial
702f2db2e6cSHeiko Carstens 			 * interrupt. Set pfault_wait to -1 so the initial
703fa2fb2f4SHeiko Carstens 			 * interrupt doesn't put the task to sleep.
704fa2fb2f4SHeiko Carstens 			 * If the task is not running, ignore the completion
705fa2fb2f4SHeiko Carstens 			 * interrupt since it must be a leftover of a PFAULT
706fa2fb2f4SHeiko Carstens 			 * CANCEL operation which didn't remove all pending
707fa2fb2f4SHeiko Carstens 			 * completion interrupts. */
708fa2fb2f4SHeiko Carstens 			if (tsk->state == TASK_RUNNING)
709f2db2e6cSHeiko Carstens 				tsk->thread.pfault_wait = -1;
7101da177e4SLinus Torvalds 		}
7111da177e4SLinus Torvalds 	} else {
7121da177e4SLinus Torvalds 		/* signal bit not set -> a real page is missing. */
713d49f47f8SHeiko Carstens 		if (WARN_ON_ONCE(tsk != current))
714d49f47f8SHeiko Carstens 			goto out;
715d5e50a51SHeiko Carstens 		if (tsk->thread.pfault_wait == 1) {
716d5e50a51SHeiko Carstens 			/* Already on the list with a reference: put to sleep */
7170a16ba78SHeiko Carstens 			__set_task_state(tsk, TASK_UNINTERRUPTIBLE);
718d5e50a51SHeiko Carstens 			set_tsk_need_resched(tsk);
719d5e50a51SHeiko Carstens 		} else if (tsk->thread.pfault_wait == -1) {
7201da177e4SLinus Torvalds 			/* Completion interrupt was faster than the initial
721f2db2e6cSHeiko Carstens 			 * interrupt (pfault_wait == -1). Set pfault_wait
722f2db2e6cSHeiko Carstens 			 * back to zero and exit. */
7231da177e4SLinus Torvalds 			tsk->thread.pfault_wait = 0;
724f2db2e6cSHeiko Carstens 		} else {
725f2db2e6cSHeiko Carstens 			/* Initial interrupt arrived before completion
726d5e50a51SHeiko Carstens 			 * interrupt. Let the task sleep.
727d5e50a51SHeiko Carstens 			 * An extra task reference is needed since a different
728d5e50a51SHeiko Carstens 			 * cpu may set the task state to TASK_RUNNING again
729d5e50a51SHeiko Carstens 			 * before the scheduler is reached. */
730d5e50a51SHeiko Carstens 			get_task_struct(tsk);
731f2db2e6cSHeiko Carstens 			tsk->thread.pfault_wait = 1;
732f2db2e6cSHeiko Carstens 			list_add(&tsk->thread.list, &pfault_list);
7330a16ba78SHeiko Carstens 			__set_task_state(tsk, TASK_UNINTERRUPTIBLE);
7341da177e4SLinus Torvalds 			set_tsk_need_resched(tsk);
7351da177e4SLinus Torvalds 		}
7361da177e4SLinus Torvalds 	}
737d49f47f8SHeiko Carstens out:
738f2db2e6cSHeiko Carstens 	spin_unlock(&pfault_lock);
73954c27791SHeiko Carstens 	put_task_struct(tsk);
740f2db2e6cSHeiko Carstens }
741f2db2e6cSHeiko Carstens 
742e2741f17SPaul Gortmaker static int pfault_cpu_notify(struct notifier_block *self, unsigned long action,
743e2741f17SPaul Gortmaker 			     void *hcpu)
744f2db2e6cSHeiko Carstens {
745f2db2e6cSHeiko Carstens 	struct thread_struct *thread, *next;
746f2db2e6cSHeiko Carstens 	struct task_struct *tsk;
747f2db2e6cSHeiko Carstens 
7481c725922SHeiko Carstens 	switch (action & ~CPU_TASKS_FROZEN) {
749f2db2e6cSHeiko Carstens 	case CPU_DEAD:
750f2db2e6cSHeiko Carstens 		spin_lock_irq(&pfault_lock);
751f2db2e6cSHeiko Carstens 		list_for_each_entry_safe(thread, next, &pfault_list, list) {
752f2db2e6cSHeiko Carstens 			thread->pfault_wait = 0;
753f2db2e6cSHeiko Carstens 			list_del(&thread->list);
754f2db2e6cSHeiko Carstens 			tsk = container_of(thread, struct task_struct, thread);
755f2db2e6cSHeiko Carstens 			wake_up_process(tsk);
756d5e50a51SHeiko Carstens 			put_task_struct(tsk);
757f2db2e6cSHeiko Carstens 		}
758f2db2e6cSHeiko Carstens 		spin_unlock_irq(&pfault_lock);
759f2db2e6cSHeiko Carstens 		break;
760f2db2e6cSHeiko Carstens 	default:
761f2db2e6cSHeiko Carstens 		break;
762f2db2e6cSHeiko Carstens 	}
763f2db2e6cSHeiko Carstens 	return NOTIFY_OK;
764f2db2e6cSHeiko Carstens }
7651da177e4SLinus Torvalds 
766fb0a9d7eSHeiko Carstens static int __init pfault_irq_init(void)
76729b08d2bSHeiko Carstens {
768fb0a9d7eSHeiko Carstens 	int rc;
76929b08d2bSHeiko Carstens 
7701dad093bSThomas Huth 	rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
7717dd8fe1fSHeiko Carstens 	if (rc)
7727dd8fe1fSHeiko Carstens 		goto out_extint;
7737dd8fe1fSHeiko Carstens 	rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
7747dd8fe1fSHeiko Carstens 	if (rc)
7757dd8fe1fSHeiko Carstens 		goto out_pfault;
77682003c3eSHeiko Carstens 	irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
7777dd8fe1fSHeiko Carstens 	hotcpu_notifier(pfault_cpu_notify, 0);
7787dd8fe1fSHeiko Carstens 	return 0;
7797dd8fe1fSHeiko Carstens 
7807dd8fe1fSHeiko Carstens out_pfault:
7811dad093bSThomas Huth 	unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
7827dd8fe1fSHeiko Carstens out_extint:
783fb0a9d7eSHeiko Carstens 	pfault_disable = 1;
784fb0a9d7eSHeiko Carstens 	return rc;
785fb0a9d7eSHeiko Carstens }
786fb0a9d7eSHeiko Carstens early_initcall(pfault_irq_init);
787fb0a9d7eSHeiko Carstens 
7887dd8fe1fSHeiko Carstens #endif /* CONFIG_PFAULT */
789