1 files changed, 235 insertions, 0 deletions

diff --git a/arch/score/mm/fault.c b/arch/score/mm/fault.c
new file mode 100644
index 000000000000..47b600e4b2c5
--- /dev/null
+++ b/arch/score/mm/fault.c
@@ -0,0 +1,235 @@
+/*
+ * arch/score/mm/fault.c
+ *
+ * Score Processor version.
+ *
+ * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
+ *  Lennox Wu <lennox.wu@sunplusct.com>
+ *  Chen Liqin <liqin.chen@sunplusct.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/module.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/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;
+        int fault;
+
+        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 && address <= VMALLOC_END))
+                goto vmalloc_fault;
+#ifdef MODULE_START
+        if (unlikely(address >= MODULE_START && address < MODULE_END))
+                goto vmalloc_fault;
+#endif
+
+        /*
+        * 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_WRITE | 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.
+        */
+        fault = handle_mm_fault(mm, vma, address, write);
+        if (unlikely(fault & VM_FAULT_ERROR)) {
+                if (fault & VM_FAULT_OOM)
+                        goto out_of_memory;
+                else if (fault & VM_FAULT_SIGBUS)
+                        goto do_sigbus;
+                BUG();
+        }
+        if (fault & VM_FAULT_MAJOR)
+                tsk->maj_flt++;
+        else
+                tsk->min_flt++;
+
+        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;
+                info.si_signo = SIGSEGV;
+                info.si_errno = 0;
+                /* info.si_code has been set above */
+                info.si_addr = (void __user *) 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",
+                        0, field, address, field, regs->cp0_epc,
+                        field, regs->regs[3]);
+        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 (is_global_init(tsk)) {
+                yield();
+                down_read(&mm->mmap_sem);
+                goto survive;
+        }
+        printk("VM: killing process %s\n", tsk->comm);
+        if (user_mode(regs))
+                do_group_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;
+        else
+        /*
+        * 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 __user *) 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;
+                pud_t *pud, *pud_k;
+                pmd_t *pmd, *pmd_k;
+                pte_t *pte_k;
+
+                pgd = (pgd_t *) pgd_current + offset;
+                pgd_k = init_mm.pgd + offset;
+
+                if (!pgd_present(*pgd_k))
+                        goto no_context;
+                set_pgd(pgd, *pgd_k);
+
+                pud = pud_offset(pgd, address);
+                pud_k = pud_offset(pgd_k, address);
+                if (!pud_present(*pud_k))
+                        goto no_context;
+
+                pmd = pmd_offset(pud, address);
+                pmd_k = pmd_offset(pud_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;
+        }
+}