1 files changed, 241 insertions, 0 deletions

diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
new file mode 100644
index 000000000000..a945a33e85a1
--- /dev/null
+++ b/arch/xtensa/mm/fault.c
@@ -0,0 +1,241 @@
+// TODO VM_EXEC flag work-around, cache aliasing
+/*
+ * arch/xtensa/mm/fault.c
+ *
+ * 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) 2001 - 2005 Tensilica Inc.
+ *
+ * Chris Zankel <chris@zankel.net>
+ * Joe Taylor   <joe@tensilica.com, joetylr@yahoo.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <asm/mmu_context.h>
+#include <asm/cacheflush.h>
+#include <asm/hardirq.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/pgalloc.h>
+
+unsigned long asid_cache = ASID_FIRST_VERSION;
+void bad_page_fault(struct pt_regs*, unsigned long, int);
+
+/*
+ * This routine handles page faults.  It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ *
+ * Note: does not handle Miss and MultiHit.
+ */
+
+void do_page_fault(struct pt_regs *regs)
+{
+        struct vm_area_struct * vma;
+        struct mm_struct *mm = current->mm;
+        unsigned int exccause = regs->exccause;
+        unsigned int address = regs->excvaddr;
+        siginfo_t info;
+
+        int is_write, is_exec;
+
+        info.si_code = SEGV_MAPERR;
+
+        /* We fault-in kernel-space virtual memory on-demand. The
+         * 'reference' page table is init_mm.pgd.
+         */
+        if (address >= TASK_SIZE && !user_mode(regs))
+                goto vmalloc_fault;
+
+        /* If we're in an interrupt or have no user
+         * context, we must not take the fault..
+         */
+        if (in_atomic() || !mm) {
+                bad_page_fault(regs, address, SIGSEGV);
+                return;
+        }
+
+        is_write = (exccause == XCHAL_EXCCAUSE_STORE_CACHE_ATTRIBUTE) ? 1 : 0;
+        is_exec =  (exccause == XCHAL_EXCCAUSE_ITLB_PRIVILEGE ||
+                    exccause == XCHAL_EXCCAUSE_ITLB_MISS ||
+                    exccause == XCHAL_EXCCAUSE_FETCH_CACHE_ATTRIBUTE) ? 1 : 0;
+
+#if 0
+        printk("[%s:%d:%08x:%d:%08x:%s%s]\n", current->comm, current->pid,
+               address, exccause, regs->pc, is_write? "w":"", is_exec? "x":"");
+#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:
+        info.si_code = SEGV_ACCERR;
+
+        if (is_write) {
+                if (!(vma->vm_flags & VM_WRITE))
+                        goto bad_area;
+        } else if (is_exec) {
+                if (!(vma->vm_flags & VM_EXEC))
+                        goto bad_area;
+        } else  /* Allow read even from write-only pages. */
+                if (!(vma->vm_flags & (VM_READ | VM_WRITE)))
+                        goto bad_area;
+
+        /* If for any reason at all we couldn't handle the fault,
+         * make sure we exit gracefully rather than endlessly redo
+         * the fault.
+         */
+survive:
+        switch (handle_mm_fault(mm, vma, address, is_write)) {
+        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();
+        }
+
+        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);
+        if (user_mode(regs)) {
+                current->thread.bad_vaddr = address;
+                current->thread.error_code = is_write;
+                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, current);
+                return;
+        }
+        bad_page_fault(regs, address, SIGSEGV);
+        return;
+
+
+        /* 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 (current->pid == 1) {
+                yield();
+                down_read(&mm->mmap_sem);
+                goto survive;
+        }
+        printk("VM: killing process %s\n", current->comm);
+        if (user_mode(regs))
+                do_exit(SIGKILL);
+        bad_page_fault(regs, address, SIGKILL);
+        return;
+
+do_sigbus:
+        up_read(&mm->mmap_sem);
+
+        /* Send a sigbus, regardless of whether we were in kernel
+         * or user mode.
+         */
+        current->thread.bad_vaddr = address;
+        info.si_code = SIGBUS;
+        info.si_errno = 0;
+        info.si_code = BUS_ADRERR;
+        info.si_addr = (void *) address;
+        force_sig_info(SIGBUS, &info, current);
+
+        /* Kernel mode? Handle exceptions or die */
+        if (!user_mode(regs))
+                bad_page_fault(regs, address, SIGBUS);
+
+vmalloc_fault:
+        {
+                /* Synchronize this task's top level page-table
+                 * with the 'reference' page table.
+                 */
+                struct mm_struct *act_mm = current->active_mm;
+                int index = pgd_index(address);
+                pgd_t *pgd, *pgd_k;
+                pmd_t *pmd, *pmd_k;
+                pte_t *pte_k;
+
+                if (act_mm == NULL)
+                        goto bad_page_fault;
+
+                pgd = act_mm->pgd + index;
+                pgd_k = init_mm.pgd + index;
+
+                if (!pgd_present(*pgd_k))
+                        goto bad_page_fault;
+
+                pgd_val(*pgd) = pgd_val(*pgd_k);
+
+                pmd = pmd_offset(pgd, address);
+                pmd_k = pmd_offset(pgd_k, address);
+                if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
+                        goto bad_page_fault;
+
+                pmd_val(*pmd) = pmd_val(*pmd_k);
+                pte_k = pte_offset_kernel(pmd_k, address);
+
+                if (!pte_present(*pte_k))
+                        goto bad_page_fault;
+                return;
+        }
+bad_page_fault:
+        bad_page_fault(regs, address, SIGKILL);
+        return;
+}
+
+
+void
+bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
+{
+        extern void die(const char*, struct pt_regs*, long);
+        const struct exception_table_entry *entry;
+
+        /* Are we prepared to handle this kernel fault?  */
+        if ((entry = search_exception_tables(regs->pc)) != NULL) {
+#if 1
+                printk(KERN_DEBUG "%s: Exception at pc=%#010lx (%lx)\n",
+                                current->comm, regs->pc, entry->fixup);
+#endif
+                current->thread.bad_uaddr = address;
+                regs->pc = entry->fixup;
+                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 %08lx\n pc = %08lx, ra = %08lx\n",
+               address, regs->pc, regs->areg[0]);
+        die("Oops", regs, sig);
+        do_exit(sig);
+}
+