1 files changed, 586 insertions, 0 deletions

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
new file mode 100644
index 000000000000..80306bc8c799
--- /dev/null
+++ b/arch/s390/mm/fault.c
@@ -0,0 +1,586 @@
+/*
+ *  arch/s390/mm/fault.c
+ *
+ *  S390 version
+ *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *    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/config.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/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/module.h>
+#include <linux/hardirq.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+
+#ifndef CONFIG_ARCH_S390X
+#define __FAIL_ADDR_MASK 0x7ffff000
+#define __FIXUP_MASK 0x7fffffff
+#define __SUBCODE_MASK 0x0200
+#define __PF_RES_FIELD 0ULL
+#else /* CONFIG_ARCH_S390X */
+#define __FAIL_ADDR_MASK -4096L
+#define __FIXUP_MASK ~0L
+#define __SUBCODE_MASK 0x0600
+#define __PF_RES_FIELD 0x8000000000000000ULL
+#endif /* CONFIG_ARCH_S390X */
+
+#ifdef CONFIG_SYSCTL
+extern int sysctl_userprocess_debug;
+#endif
+
+extern void die(const char *,struct pt_regs *,long);
+
+extern spinlock_t timerlist_lock;
+
+/*
+ * Unlock any spinlocks which will prevent us from getting the
+ * message out (timerlist_lock is acquired through the
+ * console unblank code)
+ */
+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;
+        }
+}
+
+/*
+ * Check which address space is addressed by the access
+ * register in S390_lowcore.exc_access_id.
+ * Returns 1 for user space and 0 for kernel space.
+ */
+static int __check_access_register(struct pt_regs *regs, int error_code)
+{
+        int areg = S390_lowcore.exc_access_id;
+
+        if (areg == 0)
+                /* Access via access register 0 -> kernel address */
+                return 0;
+        save_access_regs(current->thread.acrs);
+        if (regs && areg < NUM_ACRS && current->thread.acrs[areg] <= 1)
+                /*
+                 * access register contains 0 -> kernel address,
+                 * access register contains 1 -> user space address
+                 */
+                return current->thread.acrs[areg];
+
+        /* Something unhealthy was done with the access registers... */
+        die("page fault via unknown access register", regs, error_code);
+        do_exit(SIGKILL);
+        return 0;
+}
+
+/*
+ * Check which address space the address belongs to.
+ * Returns 1 for user space and 0 for kernel space.
+ */
+static inline int check_user_space(struct pt_regs *regs, int error_code)
+{
+        /*
+         * The lowest two bits of S390_lowcore.trans_exc_code indicate
+         * which paging table was used:
+         *   0: Primary Segment Table Descriptor
+         *   1: STD determined via access register
+         *   2: Secondary Segment Table Descriptor
+         *   3: Home Segment Table Descriptor
+         */
+        int descriptor = S390_lowcore.trans_exc_code & 3;
+        if (unlikely(descriptor == 1))
+                return __check_access_register(regs, error_code);
+        if (descriptor == 2)
+                return current->thread.mm_segment.ar4;
+        return descriptor != 0;
+}
+
+/*
+ * Send SIGSEGV to task.  This is an external routine
+ * to keep the stack usage of do_page_fault small.
+ */
+static void do_sigsegv(struct pt_regs *regs, unsigned long error_code,
+                       int si_code, unsigned long address)
+{
+        struct siginfo si;
+
+#if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG)
+#if defined(CONFIG_SYSCTL)
+        if (sysctl_userprocess_debug)
+#endif
+        {
+                printk("User process fault: interruption code 0x%lX\n",
+                       error_code);
+                printk("failing address: %lX\n", address);
+                show_regs(regs);
+        }
+#endif
+        si.si_signo = SIGSEGV;
+        si.si_code = si_code;
+        si.si_addr = (void *) address;
+        force_sig_info(SIGSEGV, &si, current);
+}
+
+/*
+ * This routine handles page faults.  It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ *
+ * error_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)
+ */
+extern inline void
+do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection)
+{
+        struct task_struct *tsk;
+        struct mm_struct *mm;
+        struct vm_area_struct * vma;
+        unsigned long address;
+        int user_address;
+        const struct exception_table_entry *fixup;
+        int si_code = SEGV_MAPERR;
+
+        tsk = current;
+        mm = tsk->mm;
+        
+        /* 
+         * 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 (is_protection && !(S390_lowcore.trans_exc_code & 4)) {
+
+                /* Low-address protection hit in kernel mode means 
+                   NULL pointer write access in kernel mode.  */
+                if (!(regs->psw.mask & PSW_MASK_PSTATE)) {
+                        address = 0;
+                        user_address = 0;
+                        goto no_context;
+                }
+
+                /* Low-address protection hit in user mode 'cannot happen'.  */
+                die ("Low-address protection", regs, error_code);
+                do_exit(SIGKILL);
+        }
+
+        /* 
+         * get the failing address 
+         * more specific the segment and page table portion of 
+         * the address 
+         */
+        address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK;
+        user_address = check_user_space(regs, error_code);
+
+        /*
+         * Verify that the fault happened in user space, that
+         * we are not in an interrupt and that there is a 
+         * user context.
+         */
+        if (user_address == 0 || in_interrupt() || !mm)
+                goto no_context;
+
+        /*
+         * When we get here, the fault happened in the current
+         * task's user address space, so we can switch on the
+         * interrupts again and then search the VMAs
+         */
+        local_irq_enable();
+
+        down_read(&mm->mmap_sem);
+
+        vma = find_vma(mm, address);
+        if (!vma)
+                goto bad_area;
+        if (vma->vm_start <= address) 
+                goto good_area;
+        if (!(vma->vm_flags & VM_GROWSDOWN))
+                goto bad_area;
+        if (expand_stack(vma, address))
+                goto bad_area;
+/*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it..
+ */
+good_area:
+        si_code = SEGV_ACCERR;
+        if (!is_protection) {
+                /* page not present, check vm flags */
+                if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
+                        goto bad_area;
+        } else {
+                if (!(vma->vm_flags & VM_WRITE))
+                        goto bad_area;
+        }
+
+survive:
+        /*
+         * If for any reason at all we couldn't handle the fault,
+         * make sure we exit gracefully rather than endlessly redo
+         * the fault.
+         */
+        switch (handle_mm_fault(mm, vma, address, is_protection)) {
+        case VM_FAULT_MINOR:
+                tsk->min_flt++;
+                break;
+        case VM_FAULT_MAJOR:
+                tsk->maj_flt++;
+                break;
+        case VM_FAULT_SIGBUS:
+                goto do_sigbus;
+        case VM_FAULT_OOM:
+                goto out_of_memory;
+        default:
+                BUG();
+        }
+
+        up_read(&mm->mmap_sem);
+        /*
+         * The instruction that caused the program check will
+         * be repeated. Don't signal single step via SIGTRAP.
+         */
+        clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
+        return;
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * Fix it, but check if it's kernel or user first..
+ */
+bad_area:
+        up_read(&mm->mmap_sem);
+
+        /* User mode accesses just cause a SIGSEGV */
+        if (regs->psw.mask & PSW_MASK_PSTATE) {
+                tsk->thread.prot_addr = address;
+                tsk->thread.trap_no = error_code;
+                do_sigsegv(regs, error_code, si_code, address);
+                return;
+        }
+
+no_context:
+        /* Are we prepared to handle this kernel fault?  */
+        fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK);
+        if (fixup) {
+                regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
+                return;
+        }
+
+/*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+        if (user_address == 0)
+                printk(KERN_ALERT "Unable to handle kernel pointer dereference"
+                       " at virtual kernel address %p\n", (void *)address);
+        else
+                printk(KERN_ALERT "Unable to handle kernel paging request"
+                       " at virtual user address %p\n", (void *)address);
+
+        die("Oops", regs, error_code);
+        do_exit(SIGKILL);
+
+
+/*
+ * We ran out of memory, or some other thing happened to us that made
+ * us unable to handle the page fault gracefully.
+*/
+out_of_memory:
+        up_read(&mm->mmap_sem);
+        if (tsk->pid == 1) {
+                yield();
+                goto survive;
+        }
+        printk("VM: killing process %s\n", tsk->comm);
+        if (regs->psw.mask & PSW_MASK_PSTATE)
+                do_exit(SIGKILL);
+        goto no_context;
+
+do_sigbus:
+        up_read(&mm->mmap_sem);
+
+        /*
+         * Send a sigbus, regardless of whether we were in kernel
+         * or user mode.
+         */
+        tsk->thread.prot_addr = address;
+        tsk->thread.trap_no = error_code;
+        force_sig(SIGBUS, tsk);
+
+        /* Kernel mode? Handle exceptions or die */
+        if (!(regs->psw.mask & PSW_MASK_PSTATE))
+                goto no_context;
+}
+
+void do_protection_exception(struct pt_regs *regs, unsigned long error_code)
+{
+        regs->psw.addr -= (error_code >> 16);
+        do_exception(regs, 4, 1);
+}
+
+void do_dat_exception(struct pt_regs *regs, unsigned long error_code)
+{
+        do_exception(regs, error_code & 0xff, 0);
+}
+
+#ifndef CONFIG_ARCH_S390X
+
+typedef struct _pseudo_wait_t {
+       struct _pseudo_wait_t *next;
+       wait_queue_head_t queue;
+       unsigned long address;
+       int resolved;
+} pseudo_wait_t;
+
+static pseudo_wait_t *pseudo_lock_queue = NULL;
+static spinlock_t pseudo_wait_spinlock; /* spinlock to protect lock queue */
+
+/*
+ * This routine handles 'pagex' pseudo page faults.
+ */
+asmlinkage void
+do_pseudo_page_fault(struct pt_regs *regs, unsigned long error_code)
+{
+        pseudo_wait_t wait_struct;
+        pseudo_wait_t *ptr, *last, *next;
+        unsigned long address;
+
+        /*
+         * get the failing address
+         * more specific the segment and page table portion of
+         * the address
+         */
+        address = S390_lowcore.trans_exc_code & 0xfffff000;
+
+        if (address & 0x80000000) {
+                /* high bit set -> a page has been swapped in by VM */
+                address &= 0x7fffffff;
+                spin_lock(&pseudo_wait_spinlock);
+                last = NULL;
+                ptr = pseudo_lock_queue;
+                while (ptr != NULL) {
+                        next = ptr->next;
+                        if (address == ptr->address) {
+                                 /*
+                                 * This is one of the processes waiting
+                                 * for the page. Unchain from the queue.
+                                 * There can be more than one process
+                                 * waiting for the same page. VM presents
+                                 * an initial and a completion interrupt for
+                                 * every process that tries to access a 
+                                 * page swapped out by VM. 
+                                 */
+                                if (last == NULL)
+                                        pseudo_lock_queue = next;
+                                else
+                                        last->next = next;
+                                /* now wake up the process */
+                                ptr->resolved = 1;
+                                wake_up(&ptr->queue);
+                        } else
+                                last = ptr;
+                        ptr = next;
+                }
+                spin_unlock(&pseudo_wait_spinlock);
+        } else {
+                /* Pseudo page faults in kernel mode is a bad idea */
+                if (!(regs->psw.mask & PSW_MASK_PSTATE)) {
+                        /*
+                         * VM presents pseudo page faults if the interrupted
+                         * state was not disabled for interrupts. So we can
+                         * get pseudo page fault interrupts while running
+                         * in kernel mode. We simply access the page here
+                         * while we are running disabled. VM will then swap
+                         * in the page synchronously.
+                         */
+                         if (check_user_space(regs, error_code) == 0)
+                                 /* dereference a virtual kernel address */
+                                 __asm__ __volatile__ (
+                                         "  ic 0,0(%0)"
+                                         : : "a" (address) : "0");
+                         else
+                                 /* dereference a virtual user address */
+                                 __asm__ __volatile__ (
+                                         "  la   2,0(%0)\n"
+                                         "  sacf 512\n"
+                                         "  ic   2,0(2)\n"
+                                         "0:sacf 0\n"
+                                         ".section __ex_table,\"a\"\n"
+                                         "  .align 4\n"
+                                         "  .long  0b,0b\n"
+                                         ".previous"
+                                         : : "a" (address) : "2" );
+
+                        return;
+                }
+                /* initialize and add element to pseudo_lock_queue */
+                init_waitqueue_head (&wait_struct.queue);
+                wait_struct.address = address;
+                wait_struct.resolved = 0;
+                spin_lock(&pseudo_wait_spinlock);
+                wait_struct.next = pseudo_lock_queue;
+                pseudo_lock_queue = &wait_struct;
+                spin_unlock(&pseudo_wait_spinlock);
+                /*
+                 * The instruction that caused the program check will
+                 * be repeated. Don't signal single step via SIGTRAP.
+                 */
+                clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
+                /* go to sleep */
+                wait_event(wait_struct.queue, wait_struct.resolved);
+        }
+}
+#endif /* CONFIG_ARCH_S390X */
+
+#ifdef CONFIG_PFAULT 
+/*
+ * 'pfault' pseudo page faults routines.
+ */
+static int pfault_disable = 0;
+
+static int __init nopfault(char *str)
+{
+        pfault_disable = 1;
+        return 1;
+}
+
+__setup("nopfault", nopfault);
+
+typedef struct {
+        __u16 refdiagc;
+        __u16 reffcode;
+        __u16 refdwlen;
+        __u16 refversn;
+        __u64 refgaddr;
+        __u64 refselmk;
+        __u64 refcmpmk;
+        __u64 reserved;
+} __attribute__ ((packed)) pfault_refbk_t;
+
+int pfault_init(void)
+{
+        pfault_refbk_t refbk =
+                { 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48,
+                  __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"
+                ".section __ex_table,\"a\"\n"
+                "   .align 4\n"
+#ifndef CONFIG_ARCH_S390X
+                "   .long  0b,1b\n"
+#else /* CONFIG_ARCH_S390X */
+                "   .quad  0b,1b\n"
+#endif /* CONFIG_ARCH_S390X */
+                ".previous"
+                : "=d" (rc) : "a" (&refbk) : "cc" );
+        __ctl_set_bit(0, 9);
+        return rc;
+}
+
+void pfault_fini(void)
+{
+        pfault_refbk_t refbk =
+        { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL };
+
+        if (pfault_disable)
+                return;
+        __ctl_clear_bit(0,9);
+        __asm__ __volatile__(
+                "    diag  %0,0,0x258\n"
+                "0:\n"
+                ".section __ex_table,\"a\"\n"
+                "   .align 4\n"
+#ifndef CONFIG_ARCH_S390X
+                "   .long  0b,0b\n"
+#else /* CONFIG_ARCH_S390X */
+                "   .quad  0b,0b\n"
+#endif /* CONFIG_ARCH_S390X */
+                ".previous"
+                : : "a" (&refbk) : "cc" );
+}
+
+asmlinkage void
+pfault_interrupt(struct pt_regs *regs, __u16 error_code)
+{
+        struct task_struct *tsk;
+        __u16 subcode;
+
+        /*
+         * Get the external interruption subcode & pfault
+         * initial/completion signal bit. VM stores this 
+         * in the 'cpu address' field associated with the
+         * external interrupt. 
+         */
+        subcode = S390_lowcore.cpu_addr;
+        if ((subcode & 0xff00) != __SUBCODE_MASK)
+                return;
+
+        /*
+         * Get the token (= address of the task structure of the affected task).
+         */
+        tsk = *(struct task_struct **) __LC_PFAULT_INTPARM;
+
+        if (subcode & 0x0080) {
+                /* signal bit is set -> a page has been swapped in by VM */
+                if (xchg(&tsk->thread.pfault_wait, -1) != 0) {
+                        /* 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 procude new pfaults. */
+                        tsk->thread.pfault_wait = 0;
+                        wake_up_process(tsk);
+                }
+        } else {
+                /* signal bit not set -> a real page is missing. */
+                set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+                if (xchg(&tsk->thread.pfault_wait, 1) != 0) {
+                        /* Completion interrupt was faster than the initial
+                         * interrupt (swapped in a -1 for pfault_wait). Set
+                         * pfault_wait back to zero and exit. This can be
+                         * done safely because tsk is running in kernel 
+                         * mode and can't produce new pfaults. */
+                        tsk->thread.pfault_wait = 0;
+                        set_task_state(tsk, TASK_RUNNING);
+                } else
+                        set_tsk_need_resched(tsk);
+        }
+}
+#endif
+