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-rw-r--r--arch/s390/mm/fault.c586
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 00000000000..80306bc8c79
--- /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
+
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