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-rw-r--r--kernel/arch/cris/mm/fault.c388
1 files changed, 388 insertions, 0 deletions
diff --git a/kernel/arch/cris/mm/fault.c b/kernel/arch/cris/mm/fault.c
new file mode 100644
index 000000000..3066d40a6
--- /dev/null
+++ b/kernel/arch/cris/mm/fault.c
@@ -0,0 +1,388 @@
+/*
+ * arch/cris/mm/fault.c
+ *
+ * Copyright (C) 2000-2010 Axis Communications AB
+ */
+
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/wait.h>
+#include <linux/uaccess.h>
+#include <arch/system.h>
+
+extern int find_fixup_code(struct pt_regs *);
+extern void die_if_kernel(const char *, struct pt_regs *, long);
+extern void show_registers(struct pt_regs *regs);
+
+/* debug of low-level TLB reload */
+#undef DEBUG
+
+#ifdef DEBUG
+#define D(x) x
+#else
+#define D(x)
+#endif
+
+/* debug of higher-level faults */
+#define DPG(x)
+
+/* current active page directory */
+
+DEFINE_PER_CPU(pgd_t *, current_pgd);
+unsigned long cris_signal_return_page;
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ *
+ * Notice that the address we're given is aligned to the page the fault
+ * occurred in, since we only get the PFN in R_MMU_CAUSE not the complete
+ * address.
+ *
+ * error_code:
+ * bit 0 == 0 means no page found, 1 means protection fault
+ * bit 1 == 0 means read, 1 means write
+ *
+ * If this routine detects a bad access, it returns 1, otherwise it
+ * returns 0.
+ */
+
+asmlinkage void
+do_page_fault(unsigned long address, struct pt_regs *regs,
+ int protection, int writeaccess)
+{
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ struct vm_area_struct * vma;
+ siginfo_t info;
+ int fault;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+
+ D(printk(KERN_DEBUG
+ "Page fault for %lX on %X at %lX, prot %d write %d\n",
+ address, smp_processor_id(), instruction_pointer(regs),
+ protection, writeaccess));
+
+ tsk = current;
+
+ /*
+ * 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.
+ *
+ * NOTE2: This is done so that, when updating the vmalloc
+ * mappings we don't have to walk all processes pgdirs and
+ * add the high mappings all at once. Instead we do it as they
+ * are used. However vmalloc'ed page entries have the PAGE_GLOBAL
+ * bit set so sometimes the TLB can use a lingering entry.
+ *
+ * This verifies that the fault happens in kernel space
+ * and that the fault was not a protection error (error_code & 1).
+ */
+
+ if (address >= VMALLOC_START &&
+ !protection &&
+ !user_mode(regs))
+ goto vmalloc_fault;
+
+ /* When stack execution is not allowed we store the signal
+ * trampolines in the reserved cris_signal_return_page.
+ * Handle this in the exact same way as vmalloc (we know
+ * that the mapping is there and is valid so no need to
+ * call handle_mm_fault).
+ */
+ if (cris_signal_return_page &&
+ address == cris_signal_return_page &&
+ !protection && user_mode(regs))
+ goto vmalloc_fault;
+
+ /* we can and should enable interrupts at this point */
+ local_irq_enable();
+
+ mm = tsk->mm;
+ info.si_code = SEGV_MAPERR;
+
+ /*
+ * If we're in an interrupt, have pagefaults disabled or have no
+ * user context, we must not take the fault.
+ */
+
+ if (faulthandler_disabled() || !mm)
+ goto no_context;
+
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+retry:
+ 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 (user_mode(regs)) {
+ /*
+ * accessing the stack below usp is always a bug.
+ * we get page-aligned addresses so we can only check
+ * if we're within a page from usp, but that might be
+ * enough to catch brutal errors at least.
+ */
+ if (address + PAGE_SIZE < rdusp())
+ 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;
+
+ /* first do some preliminary protection checks */
+
+ if (writeaccess == 2){
+ if (!(vma->vm_flags & VM_EXEC))
+ goto bad_area;
+ } else if (writeaccess == 1) {
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ flags |= FAULT_FLAG_WRITE;
+ } else {
+ if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
+ 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.
+ */
+
+ fault = handle_mm_fault(mm, vma, address, flags);
+
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return;
+
+ if (unlikely(fault & VM_FAULT_ERROR)) {
+ if (fault & VM_FAULT_OOM)
+ goto out_of_memory;
+ else if (fault & VM_FAULT_SIGSEGV)
+ goto bad_area;
+ else if (fault & VM_FAULT_SIGBUS)
+ goto do_sigbus;
+ BUG();
+ }
+
+ if (flags & FAULT_FLAG_ALLOW_RETRY) {
+ if (fault & VM_FAULT_MAJOR)
+ tsk->maj_flt++;
+ else
+ tsk->min_flt++;
+ if (fault & VM_FAULT_RETRY) {
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
+
+ /*
+ * No need to up_read(&mm->mmap_sem) as we would
+ * have already released it in __lock_page_or_retry
+ * in mm/filemap.c.
+ */
+
+ goto retry;
+ }
+ }
+
+ 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:
+ DPG(show_registers(regs));
+
+ /* User mode accesses just cause a SIGSEGV */
+
+ if (user_mode(regs)) {
+#ifdef CONFIG_NO_SEGFAULT_TERMINATION
+ DECLARE_WAIT_QUEUE_HEAD(wq);
+#endif
+ printk(KERN_NOTICE "%s (pid %d) segfaults for page "
+ "address %08lx at pc %08lx\n",
+ tsk->comm, tsk->pid,
+ address, instruction_pointer(regs));
+
+ /* With DPG on, we've already dumped registers above. */
+ DPG(if (0))
+ show_registers(regs);
+
+#ifdef CONFIG_NO_SEGFAULT_TERMINATION
+ wait_event_interruptible(wq, 0 == 1);
+#else
+ 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);
+#endif
+ return;
+ }
+
+ no_context:
+
+ /* Are we prepared to handle this kernel fault?
+ *
+ * (The kernel has valid exception-points in the source
+ * when it accesses user-memory. When it fails in one
+ * of those points, we find it in a table and do a jump
+ * to some fixup code that loads an appropriate error
+ * code)
+ */
+
+ if (find_fixup_code(regs))
+ return;
+
+ /*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+
+ if (!oops_in_progress) {
+ oops_in_progress = 1;
+ if ((unsigned long) (address) < PAGE_SIZE)
+ printk(KERN_ALERT "Unable to handle kernel NULL "
+ "pointer dereference");
+ else
+ printk(KERN_ALERT "Unable to handle kernel access"
+ " at virtual address %08lx\n", address);
+
+ die_if_kernel("Oops", regs, (writeaccess << 1) | protection);
+ oops_in_progress = 0;
+ }
+
+ 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 (!user_mode(regs))
+ goto no_context;
+ pagefault_out_of_memory();
+ return;
+
+ do_sigbus:
+ up_read(&mm->mmap_sem);
+
+ /*
+ * 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 *)address;
+ force_sig_info(SIGBUS, &info, tsk);
+
+ /* Kernel mode? Handle exceptions or die */
+ if (!user_mode(regs))
+ goto no_context;
+ return;
+
+vmalloc_fault:
+ {
+ /*
+ * Synchronize this task's top level page-table
+ * with the 'reference' page table.
+ *
+ * Use current_pgd instead of tsk->active_mm->pgd
+ * since the latter might be unavailable if this
+ * code is executed in a misfortunately run irq
+ * (like inside schedule() between switch_mm and
+ * switch_to...).
+ */
+
+ int offset = pgd_index(address);
+ pgd_t *pgd, *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+ pte_t *pte_k;
+
+ pgd = (pgd_t *)per_cpu(current_pgd, smp_processor_id()) + offset;
+ pgd_k = init_mm.pgd + offset;
+
+ /* Since we're two-level, we don't need to do both
+ * set_pgd and set_pmd (they do the same thing). If
+ * we go three-level at some point, do the right thing
+ * with pgd_present and set_pgd here.
+ *
+ * Also, since the vmalloc area is global, we don't
+ * need to copy individual PTE's, it is enough to
+ * copy the pgd pointer into the pte page of the
+ * root task. If that is there, we'll find our pte if
+ * it exists.
+ */
+
+ 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 bad_area_nosemaphore;
+
+ set_pmd(pmd, *pmd_k);
+
+ /* Make sure the actual PTE exists as well to
+ * catch kernel vmalloc-area accesses to non-mapped
+ * addresses. If we don't do this, this will just
+ * silently loop forever.
+ */
+
+ pte_k = pte_offset_kernel(pmd_k, address);
+ if (!pte_present(*pte_k))
+ goto no_context;
+
+ return;
+ }
+}
+
+/* Find fixup code. */
+int
+find_fixup_code(struct pt_regs *regs)
+{
+ const struct exception_table_entry *fixup;
+ /* in case of delay slot fault (v32) */
+ unsigned long ip = (instruction_pointer(regs) & ~0x1);
+
+ fixup = search_exception_tables(ip);
+ if (fixup != 0) {
+ /* Adjust the instruction pointer in the stackframe. */
+ instruction_pointer(regs) = fixup->fixup;
+ arch_fixup(regs);
+ return 1;
+ }
+
+ return 0;
+}