1 files changed, 236 insertions, 0 deletions

diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
new file mode 100644
index 000000000000..ec8077c74e9c
--- /dev/null
+++ b/arch/mips/mm/fault.c
@@ -0,0 +1,236 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1995 - 2000 by Ralf Baechle
+ */
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/interrupt.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/vt_kern.h>              /* For unblank_screen() */
+#include <linux/module.h>
+
+#include <asm/branch.h>
+#include <asm/mmu_context.h>
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/ptrace.h>
+
+/*
+ * This routine handles page faults.  It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ */
+asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
+                              unsigned long address)
+{
+        struct vm_area_struct * vma = NULL;
+        struct task_struct *tsk = current;
+        struct mm_struct *mm = tsk->mm;
+        const int field = sizeof(unsigned long) * 2;
+        siginfo_t info;
+
+#if 0
+        printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", smp_processor_id(),
+               current->comm, current->pid, field, address, write,
+               field, regs->cp0_epc);
+#endif
+
+        info.si_code = SEGV_MAPERR;
+
+        /*
+         * We fault-in kernel-space virtual memory on-demand. The
+         * 'reference' page table is init_mm.pgd.
+         *
+         * NOTE! We MUST NOT take any locks for this case. We may
+         * be in an interrupt or a critical region, and should
+         * only copy the information from the master page table,
+         * nothing more.
+         */
+        if (unlikely(address >= VMALLOC_START))
+                goto vmalloc_fault;
+
+        /*
+         * If we're in an interrupt or have no user
+         * context, we must not take the fault..
+         */
+        if (in_atomic() || !mm)
+                goto bad_area_nosemaphore;
+
+        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:
+        info.si_code = SEGV_ACCERR;
+
+        if (write) {
+                if (!(vma->vm_flags & VM_WRITE))
+                        goto bad_area;
+        } else {
+                if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
+                        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, write)) {
+        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);
+        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);
+
+bad_area_nosemaphore:
+        /* User mode accesses just cause a SIGSEGV */
+        if (user_mode(regs)) {
+                tsk->thread.cp0_badvaddr = address;
+                tsk->thread.error_code = write;
+#if 0
+                printk("do_page_fault() #2: sending SIGSEGV to %s for "
+                       "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
+                       tsk->comm,
+                       write ? "write access to" : "read access from",
+                       field, address,
+                       field, (unsigned long) regs->cp0_epc,
+                       field, (unsigned long) regs->regs[31]);
+#endif
+                info.si_signo = SIGSEGV;
+                info.si_errno = 0;
+                /* info.si_code has been set above */
+                info.si_addr = (void *) address;
+                force_sig_info(SIGSEGV, &info, tsk);
+                return;
+        }
+
+no_context:
+        /* Are we prepared to handle this kernel fault?  */
+        if (fixup_exception(regs)) {
+                current->thread.cp0_baduaddr = address;
+                return;
+        }
+
+        /*
+         * Oops. The kernel tried to access some bad page. We'll have to
+         * terminate things with extreme prejudice.
+         */
+
+        bust_spinlocks(1);
+
+        printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
+               "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
+               smp_processor_id(), field, address, field, regs->cp0_epc,
+               field,  regs->regs[31]);
+        die("Oops", regs);
+
+/*
+ * 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();
+                down_read(&mm->mmap_sem);
+                goto survive;
+        }
+        printk("VM: killing process %s\n", tsk->comm);
+        if (user_mode(regs))
+                do_exit(SIGKILL);
+        goto no_context;
+
+do_sigbus:
+        up_read(&mm->mmap_sem);
+
+        /* Kernel mode? Handle exceptions or die */
+        if (!user_mode(regs))
+                goto no_context;
+
+        /*
+         * Send a sigbus, regardless of whether we were in kernel
+         * or user mode.
+         */
+        tsk->thread.cp0_badvaddr = address;
+        info.si_signo = SIGBUS;
+        info.si_errno = 0;
+        info.si_code = BUS_ADRERR;
+        info.si_addr = (void *) address;
+        force_sig_info(SIGBUS, &info, tsk);
+
+        return;
+
+vmalloc_fault:
+        {
+                /*
+                 * Synchronize this task's top level page-table
+                 * with the 'reference' page table.
+                 *
+                 * Do _not_ use "tsk" here. We might be inside
+                 * an interrupt in the middle of a task switch..
+                 */
+                int offset = __pgd_offset(address);
+                pgd_t *pgd, *pgd_k;
+                pmd_t *pmd, *pmd_k;
+                pte_t *pte_k;
+
+                pgd = (pgd_t *) pgd_current[smp_processor_id()] + offset;
+                pgd_k = init_mm.pgd + offset;
+
+                if (!pgd_present(*pgd_k))
+                        goto no_context;
+                set_pgd(pgd, *pgd_k);
+
+                pmd = pmd_offset(pgd, address);
+                pmd_k = pmd_offset(pgd_k, address);
+                if (!pmd_present(*pmd_k))
+                        goto no_context;
+                set_pmd(pmd, *pmd_k);
+
+                pte_k = pte_offset_kernel(pmd_k, address);
+                if (!pte_present(*pte_k))
+                        goto no_context;
+                return;
+        }
+}