1 files changed, 247 insertions, 0 deletions

diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
new file mode 100644
index 000000000000..64ace5a9cd3d
--- /dev/null
+++ b/arch/alpha/mm/fault.c
@@ -0,0 +1,247 @@
+/*
+ *  linux/arch/alpha/mm/fault.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ */
+
+#include <linux/config.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <asm/io.h>
+
+#define __EXTERN_INLINE inline
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+#undef  __EXTERN_INLINE
+
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+
+extern void die_if_kernel(char *,struct pt_regs *,long, unsigned long *);
+
+
+/*
+ * Force a new ASN for a task.
+ */
+
+#ifndef CONFIG_SMP
+unsigned long last_asn = ASN_FIRST_VERSION;
+#endif
+
+void
+__load_new_mm_context(struct mm_struct *next_mm)
+{
+        unsigned long mmc;
+        struct pcb_struct *pcb;
+
+        mmc = __get_new_mm_context(next_mm, smp_processor_id());
+        next_mm->context[smp_processor_id()] = mmc;
+
+        pcb = &current_thread_info()->pcb;
+        pcb->asn = mmc & HARDWARE_ASN_MASK;
+        pcb->ptbr = ((unsigned long) next_mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
+
+        __reload_thread(pcb);
+}
+
+
+/*
+ * This routine handles page faults.  It determines the address,
+ * and the problem, and then passes it off to handle_mm_fault().
+ *
+ * mmcsr:
+ *      0 = translation not valid
+ *      1 = access violation
+ *      2 = fault-on-read
+ *      3 = fault-on-execute
+ *      4 = fault-on-write
+ *
+ * cause:
+ *      -1 = instruction fetch
+ *      0 = load
+ *      1 = store
+ *
+ * Registers $9 through $15 are saved in a block just prior to `regs' and
+ * are saved and restored around the call to allow exception code to
+ * modify them.
+ */
+
+/* Macro for exception fixup code to access integer registers.  */
+#define dpf_reg(r)                                                      \
+        (((unsigned long *)regs)[(r) <= 8 ? (r) : (r) <= 15 ? (r)-16 :  \
+                                 (r) <= 18 ? (r)+8 : (r)-10])
+
+asmlinkage void
+do_page_fault(unsigned long address, unsigned long mmcsr,
+              long cause, struct pt_regs *regs)
+{
+        struct vm_area_struct * vma;
+        struct mm_struct *mm = current->mm;
+        const struct exception_table_entry *fixup;
+        int fault, si_code = SEGV_MAPERR;
+        siginfo_t info;
+
+        /* As of EV6, a load into $31/$f31 is a prefetch, and never faults
+           (or is suppressed by the PALcode).  Support that for older CPUs
+           by ignoring such an instruction.  */
+        if (cause == 0) {
+                unsigned int insn;
+                __get_user(insn, (unsigned int __user *)regs->pc);
+                if ((insn >> 21 & 0x1f) == 0x1f &&
+                    /* ldq ldl ldt lds ldg ldf ldwu ldbu */
+                    (1ul << (insn >> 26) & 0x30f00001400ul)) {
+                        regs->pc += 4;
+                        return;
+                }
+        }
+
+        /* If we're in an interrupt context, or have no user context,
+           we must not take the fault.  */
+        if (!mm || in_interrupt())
+                goto no_context;
+
+#ifdef CONFIG_ALPHA_LARGE_VMALLOC
+        if (address >= TASK_SIZE)
+                goto vmalloc_fault;
+#endif
+
+        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 (cause < 0) {
+                if (!(vma->vm_flags & VM_EXEC))
+                        goto bad_area;
+        } else if (!cause) {
+                /* Allow reads even for write-only mappings */
+                if (!(vma->vm_flags & (VM_READ | 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.  */
+        fault = handle_mm_fault(mm, vma, address, cause > 0);
+        up_read(&mm->mmap_sem);
+
+        switch (fault) {
+              case VM_FAULT_MINOR:
+                current->min_flt++;
+                break;
+              case VM_FAULT_MAJOR:
+                current->maj_flt++;
+                break;
+              case VM_FAULT_SIGBUS:
+                goto do_sigbus;
+              case VM_FAULT_OOM:
+                goto out_of_memory;
+              default:
+                BUG();
+        }
+        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);
+
+        if (user_mode(regs))
+                goto do_sigsegv;
+
+ no_context:
+        /* Are we prepared to handle this fault as an exception?  */
+        if ((fixup = search_exception_tables(regs->pc)) != 0) {
+                unsigned long newpc;
+                newpc = fixup_exception(dpf_reg, fixup, regs->pc);
+                regs->pc = newpc;
+                return;
+        }
+
+        /* Oops. The kernel tried to access some bad page. We'll have to
+           terminate things with extreme prejudice.  */
+        printk(KERN_ALERT "Unable to handle kernel paging request at "
+               "virtual address %016lx\n", address);
+        die_if_kernel("Oops", regs, cause, (unsigned long*)regs - 16);
+        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:
+        if (current->pid == 1) {
+                yield();
+                down_read(&mm->mmap_sem);
+                goto survive;
+        }
+        printk(KERN_ALERT "VM: killing process %s(%d)\n",
+               current->comm, current->pid);
+        if (!user_mode(regs))
+                goto no_context;
+        do_exit(SIGKILL);
+
+ do_sigbus:
+        /* Send a sigbus, regardless of whether we were in kernel
+           or user mode.  */
+        info.si_signo = SIGBUS;
+        info.si_errno = 0;
+        info.si_code = BUS_ADRERR;
+        info.si_addr = (void __user *) address;
+        force_sig_info(SIGBUS, &info, current);
+        if (!user_mode(regs))
+                goto no_context;
+        return;
+
+ do_sigsegv:
+        info.si_signo = SIGSEGV;
+        info.si_errno = 0;
+        info.si_code = si_code;
+        info.si_addr = (void __user *) address;
+        force_sig_info(SIGSEGV, &info, current);
+        return;
+
+#ifdef CONFIG_ALPHA_LARGE_VMALLOC
+ vmalloc_fault:
+        if (user_mode(regs))
+                goto do_sigsegv;
+        else {
+                /* Synchronize this task's top level page-table
+                   with the "reference" page table from init.  */
+                long index = pgd_index(address);
+                pgd_t *pgd, *pgd_k;
+
+                pgd = current->active_mm->pgd + index;
+                pgd_k = swapper_pg_dir + index;
+                if (!pgd_present(*pgd) && pgd_present(*pgd_k)) {
+                        pgd_val(*pgd) = pgd_val(*pgd_k);
+                        return;
+                }
+                goto no_context;
+        }
+#endif
+}