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-rw-r--r--arch/nios2/mm/fault.c261
1 files changed, 261 insertions, 0 deletions
diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c
new file mode 100644
index 000000000..71939fb28
--- /dev/null
+++ b/arch/nios2/mm/fault.c
@@ -0,0 +1,261 @@
+/*
+ * Copyright (C) 2009 Wind River Systems Inc
+ * Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
+ *
+ * based on arch/mips/mm/fault.c which is:
+ *
+ * Copyright (C) 1995-2000 Ralf Baechle
+ *
+ * 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.
+ */
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.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/extable.h>
+#include <linux/uaccess.h>
+#include <linux/perf_event.h>
+
+#include <asm/mmu_context.h>
+#include <asm/traps.h>
+
+#define EXC_SUPERV_INSN_ACCESS 9 /* Supervisor only instruction address */
+#define EXC_SUPERV_DATA_ACCESS 11 /* Supervisor only data address */
+#define EXC_X_PROTECTION_FAULT 13 /* TLB permission violation (x) */
+#define EXC_R_PROTECTION_FAULT 14 /* TLB permission violation (r) */
+#define EXC_W_PROTECTION_FAULT 15 /* TLB permission violation (w) */
+
+/*
+ * 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 cause,
+ unsigned long address)
+{
+ struct vm_area_struct *vma = NULL;
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk->mm;
+ int code = SEGV_MAPERR;
+ vm_fault_t fault;
+ unsigned int flags = FAULT_FLAG_DEFAULT;
+
+ cause >>= 2;
+
+ /* Restart the instruction */
+ regs->ea -= 4;
+
+ /*
+ * 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)) {
+ if (user_mode(regs))
+ goto bad_area_nosemaphore;
+ else
+ goto vmalloc_fault;
+ }
+
+ if (unlikely(address >= TASK_SIZE))
+ goto bad_area_nosemaphore;
+
+ /*
+ * If we're in an interrupt or have no user
+ * context, we must not take the fault..
+ */
+ if (faulthandler_disabled() || !mm)
+ goto bad_area_nosemaphore;
+
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+
+retry:
+ vma = lock_mm_and_find_vma(mm, address, regs);
+ if (!vma)
+ goto bad_area_nosemaphore;
+/*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it..
+ */
+ code = SEGV_ACCERR;
+
+ switch (cause) {
+ case EXC_SUPERV_INSN_ACCESS:
+ goto bad_area;
+ case EXC_SUPERV_DATA_ACCESS:
+ goto bad_area;
+ case EXC_X_PROTECTION_FAULT:
+ if (!(vma->vm_flags & VM_EXEC))
+ goto bad_area;
+ break;
+ case EXC_R_PROTECTION_FAULT:
+ if (!(vma->vm_flags & VM_READ))
+ goto bad_area;
+ break;
+ case EXC_W_PROTECTION_FAULT:
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ flags = FAULT_FLAG_WRITE;
+ break;
+ }
+
+ /*
+ * 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(vma, address, flags, regs);
+
+ if (fault_signal_pending(fault, regs))
+ return;
+
+ /* The fault is fully completed (including releasing mmap lock) */
+ if (fault & VM_FAULT_COMPLETED)
+ 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 (fault & VM_FAULT_RETRY) {
+ flags |= FAULT_FLAG_TRIED;
+
+ /*
+ * No need to mmap_read_unlock(mm) as we would
+ * have already released it in __lock_page_or_retry
+ * in mm/filemap.c.
+ */
+
+ goto retry;
+ }
+
+ mmap_read_unlock(mm);
+ 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:
+ mmap_read_unlock(mm);
+
+bad_area_nosemaphore:
+ /* User mode accesses just cause a SIGSEGV */
+ if (user_mode(regs)) {
+ if (unhandled_signal(current, SIGSEGV) && printk_ratelimit()) {
+ pr_info("%s: unhandled page fault (%d) at 0x%08lx, "
+ "cause %ld\n", current->comm, SIGSEGV, address, cause);
+ show_regs(regs);
+ }
+ _exception(SIGSEGV, regs, code, address);
+ return;
+ }
+
+no_context:
+ /* Are we prepared to handle this kernel fault? */
+ if (fixup_exception(regs))
+ return;
+
+ /*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+ bust_spinlocks(1);
+
+ pr_alert("Unable to handle kernel %s at virtual address %08lx",
+ address < PAGE_SIZE ? "NULL pointer dereference" :
+ "paging request", address);
+ pr_alert("ea = %08lx, ra = %08lx, cause = %ld\n", regs->ea, regs->ra,
+ cause);
+ panic("Oops");
+ 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:
+ mmap_read_unlock(mm);
+ if (!user_mode(regs))
+ goto no_context;
+ pagefault_out_of_memory();
+ return;
+
+do_sigbus:
+ mmap_read_unlock(mm);
+
+ /* Kernel mode? Handle exceptions or die */
+ if (!user_mode(regs))
+ goto no_context;
+
+ _exception(SIGBUS, regs, BUS_ADRERR, address);
+ 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_index(address);
+ pgd_t *pgd, *pgd_k;
+ p4d_t *p4d, *p4d_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+ pte_t *pte_k;
+
+ pgd = pgd_current + offset;
+ pgd_k = init_mm.pgd + offset;
+
+ if (!pgd_present(*pgd_k))
+ goto no_context;
+ set_pgd(pgd, *pgd_k);
+
+ p4d = p4d_offset(pgd, address);
+ p4d_k = p4d_offset(pgd_k, address);
+ if (!p4d_present(*p4d_k))
+ goto no_context;
+ pud = pud_offset(p4d, address);
+ pud_k = pud_offset(p4d_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;
+
+ flush_tlb_kernel_page(address);
+ return;
+ }
+}