1 files changed, 462 insertions, 0 deletions

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
new file mode 100644
index 000000000000..29be1c018949
--- /dev/null
+++ b/arch/arm/mm/fault.c
@@ -0,0 +1,462 @@
+/*
+ *  linux/arch/arm/mm/fault.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *  Modifications for ARM processor (c) 1995-2004 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/signal.h>
+#include <linux/ptrace.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+
+#include <asm/system.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/uaccess.h>
+
+#include "fault.h"
+
+/*
+ * This is useful to dump out the page tables associated with
+ * 'addr' in mm 'mm'.
+ */
+void show_pte(struct mm_struct *mm, unsigned long addr)
+{
+        pgd_t *pgd;
+
+        if (!mm)
+                mm = &init_mm;
+
+        printk(KERN_ALERT "pgd = %p\n", mm->pgd);
+        pgd = pgd_offset(mm, addr);
+        printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
+
+        do {
+                pmd_t *pmd;
+                pte_t *pte;
+
+                if (pgd_none(*pgd))
+                        break;
+
+                if (pgd_bad(*pgd)) {
+                        printk("(bad)");
+                        break;
+                }
+
+                pmd = pmd_offset(pgd, addr);
+#if PTRS_PER_PMD != 1
+                printk(", *pmd=%08lx", pmd_val(*pmd));
+#endif
+
+                if (pmd_none(*pmd))
+                        break;
+
+                if (pmd_bad(*pmd)) {
+                        printk("(bad)");
+                        break;
+                }
+
+#ifndef CONFIG_HIGHMEM
+                /* We must not map this if we have highmem enabled */
+                pte = pte_offset_map(pmd, addr);
+                printk(", *pte=%08lx", pte_val(*pte));
+                printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
+                pte_unmap(pte);
+#endif
+        } while(0);
+
+        printk("\n");
+}
+
+/*
+ * Oops.  The kernel tried to access some page that wasn't present.
+ */
+static void
+__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
+                  struct pt_regs *regs)
+{
+        /*
+         * Are we prepared to handle this kernel fault?
+         */
+        if (fixup_exception(regs))
+                return;
+
+        /*
+         * No handler, we'll have to terminate things with extreme prejudice.
+         */
+        bust_spinlocks(1);
+        printk(KERN_ALERT
+                "Unable to handle kernel %s at virtual address %08lx\n",
+                (addr < PAGE_SIZE) ? "NULL pointer dereference" :
+                "paging request", addr);
+
+        show_pte(mm, addr);
+        die("Oops", regs, fsr);
+        bust_spinlocks(0);
+        do_exit(SIGKILL);
+}
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * User mode accesses just cause a SIGSEGV
+ */
+static void
+__do_user_fault(struct task_struct *tsk, unsigned long addr,
+                unsigned int fsr, int code, struct pt_regs *regs)
+{
+        struct siginfo si;
+
+#ifdef CONFIG_DEBUG_USER
+        if (user_debug & UDBG_SEGV) {
+                printk(KERN_DEBUG "%s: unhandled page fault at 0x%08lx, code 0x%03x\n",
+                       tsk->comm, addr, fsr);
+                show_pte(tsk->mm, addr);
+                show_regs(regs);
+        }
+#endif
+
+        tsk->thread.address = addr;
+        tsk->thread.error_code = fsr;
+        tsk->thread.trap_no = 14;
+        si.si_signo = SIGSEGV;
+        si.si_errno = 0;
+        si.si_code = code;
+        si.si_addr = (void __user *)addr;
+        force_sig_info(SIGSEGV, &si, tsk);
+}
+
+void
+do_bad_area(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr,
+            unsigned int fsr, struct pt_regs *regs)
+{
+        /*
+         * If we are in kernel mode at this point, we
+         * have no context to handle this fault with.
+         */
+        if (user_mode(regs))
+                __do_user_fault(tsk, addr, fsr, SEGV_MAPERR, regs);
+        else
+                __do_kernel_fault(mm, addr, fsr, regs);
+}
+
+#define VM_FAULT_BADMAP         (-20)
+#define VM_FAULT_BADACCESS      (-21)
+
+static int
+__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
+                struct task_struct *tsk)
+{
+        struct vm_area_struct *vma;
+        int fault, mask;
+
+        vma = find_vma(mm, addr);
+        fault = VM_FAULT_BADMAP;
+        if (!vma)
+                goto out;
+        if (vma->vm_start > addr)
+                goto check_stack;
+
+        /*
+         * Ok, we have a good vm_area for this
+         * memory access, so we can handle it.
+         */
+good_area:
+        if (fsr & (1 << 11)) /* write? */
+                mask = VM_WRITE;
+        else
+                mask = VM_READ|VM_EXEC;
+
+        fault = VM_FAULT_BADACCESS;
+        if (!(vma->vm_flags & mask))
+                goto out;
+
+        /*
+         * If for any reason at all we couldn't handle
+         * the fault, make sure we exit gracefully rather
+         * than endlessly redo the fault.
+         */
+survive:
+        fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, fsr & (1 << 11));
+
+        /*
+         * Handle the "normal" cases first - successful and sigbus
+         */
+        switch (fault) {
+        case VM_FAULT_MAJOR:
+                tsk->maj_flt++;
+                return fault;
+        case VM_FAULT_MINOR:
+                tsk->min_flt++;
+        case VM_FAULT_SIGBUS:
+                return fault;
+        }
+
+        if (tsk->pid != 1)
+                goto out;
+
+        /*
+         * If we are out of memory for pid1,
+         * sleep for a while and retry
+         */
+        yield();
+        goto survive;
+
+check_stack:
+        if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
+                goto good_area;
+out:
+        return fault;
+}
+
+static int
+do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+        struct task_struct *tsk;
+        struct mm_struct *mm;
+        int fault;
+
+        tsk = current;
+        mm  = tsk->mm;
+
+        /*
+         * If we're in an interrupt or have no user
+         * context, we must not take the fault..
+         */
+        if (in_interrupt() || !mm)
+                goto no_context;
+
+        down_read(&mm->mmap_sem);
+        fault = __do_page_fault(mm, addr, fsr, tsk);
+        up_read(&mm->mmap_sem);
+
+        /*
+         * Handle the "normal" case first
+         */
+        if (fault > 0)
+                return 0;
+
+        /*
+         * We had some memory, but were unable to
+         * successfully fix up this page fault.
+         */
+        if (fault == 0)
+                goto do_sigbus;
+
+        /*
+         * If we are in kernel mode at this point, we
+         * have no context to handle this fault with.
+         */
+        if (!user_mode(regs))
+                goto no_context;
+
+        if (fault == VM_FAULT_OOM) {
+                /*
+                 * We ran out of memory, or some other thing happened to
+                 * us that made us unable to handle the page fault gracefully.
+                 */
+                printk("VM: killing process %s\n", tsk->comm);
+                do_exit(SIGKILL);
+        } else
+                __do_user_fault(tsk, addr, fsr, fault == VM_FAULT_BADACCESS ?
+                                SEGV_ACCERR : SEGV_MAPERR, regs);
+        return 0;
+
+
+/*
+ * We ran out of memory, or some other thing happened to us that made
+ * us unable to handle the page fault gracefully.
+ */
+do_sigbus:
+        /*
+         * Send a sigbus, regardless of whether we were in kernel
+         * or user mode.
+         */
+        tsk->thread.address = addr;
+        tsk->thread.error_code = fsr;
+        tsk->thread.trap_no = 14;
+        force_sig(SIGBUS, tsk);
+#ifdef CONFIG_DEBUG_USER
+        if (user_debug & UDBG_BUS) {
+                printk(KERN_DEBUG "%s: sigbus at 0x%08lx, pc=0x%08lx\n",
+                        current->comm, addr, instruction_pointer(regs));
+        }
+#endif
+
+        /* Kernel mode? Handle exceptions or die */
+        if (user_mode(regs))
+                return 0;
+
+no_context:
+        __do_kernel_fault(mm, addr, fsr, regs);
+        return 0;
+}
+
+/*
+ * First Level Translation Fault Handler
+ *
+ * We enter here because the first level page table doesn't contain
+ * a valid entry for the address.
+ *
+ * If the address is in kernel space (>= TASK_SIZE), then we are
+ * probably faulting in the vmalloc() area.
+ *
+ * If the init_task's first level page tables contains the relevant
+ * entry, we copy the it to this task.  If not, we send the process
+ * a signal, fixup the exception, or oops the kernel.
+ *
+ * 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.
+ */
+static int
+do_translation_fault(unsigned long addr, unsigned int fsr,
+                     struct pt_regs *regs)
+{
+        struct task_struct *tsk;
+        unsigned int index;
+        pgd_t *pgd, *pgd_k;
+        pmd_t *pmd, *pmd_k;
+
+        if (addr < TASK_SIZE)
+                return do_page_fault(addr, fsr, regs);
+
+        index = pgd_index(addr);
+
+        /*
+         * FIXME: CP15 C1 is write only on ARMv3 architectures.
+         */
+        pgd = cpu_get_pgd() + index;
+        pgd_k = init_mm.pgd + index;
+
+        if (pgd_none(*pgd_k))
+                goto bad_area;
+
+        if (!pgd_present(*pgd))
+                set_pgd(pgd, *pgd_k);
+
+        pmd_k = pmd_offset(pgd_k, addr);
+        pmd   = pmd_offset(pgd, addr);
+
+        if (pmd_none(*pmd_k))
+                goto bad_area;
+
+        copy_pmd(pmd, pmd_k);
+        return 0;
+
+bad_area:
+        tsk = current;
+
+        do_bad_area(tsk, tsk->active_mm, addr, fsr, regs);
+        return 0;
+}
+
+/*
+ * Some section permission faults need to be handled gracefully.
+ * They can happen due to a __{get,put}_user during an oops.
+ */
+static int
+do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+        struct task_struct *tsk = current;
+        do_bad_area(tsk, tsk->active_mm, addr, fsr, regs);
+        return 0;
+}
+
+/*
+ * This abort handler always returns "fault".
+ */
+static int
+do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+        return 1;
+}
+
+static struct fsr_info {
+        int     (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
+        int     sig;
+        const char *name;
+} fsr_info[] = {
+        /*
+         * The following are the standard ARMv3 and ARMv4 aborts.  ARMv5
+         * defines these to be "precise" aborts.
+         */
+        { do_bad,               SIGSEGV, "vector exception"                },
+        { do_bad,               SIGILL,  "alignment exception"             },
+        { do_bad,               SIGKILL, "terminal exception"              },
+        { do_bad,               SIGILL,  "alignment exception"             },
+        { do_bad,               SIGBUS,  "external abort on linefetch"     },
+        { do_translation_fault, SIGSEGV, "section translation fault"       },
+        { do_bad,               SIGBUS,  "external abort on linefetch"     },
+        { do_page_fault,        SIGSEGV, "page translation fault"          },
+        { do_bad,               SIGBUS,  "external abort on non-linefetch" },
+        { do_bad,               SIGSEGV, "section domain fault"            },
+        { do_bad,               SIGBUS,  "external abort on non-linefetch" },
+        { do_bad,               SIGSEGV, "page domain fault"               },
+        { do_bad,               SIGBUS,  "external abort on translation"   },
+        { do_sect_fault,        SIGSEGV, "section permission fault"        },
+        { do_bad,               SIGBUS,  "external abort on translation"   },
+        { do_page_fault,        SIGSEGV, "page permission fault"           },
+        /*
+         * The following are "imprecise" aborts, which are signalled by bit
+         * 10 of the FSR, and may not be recoverable.  These are only
+         * supported if the CPU abort handler supports bit 10.
+         */
+        { do_bad,               SIGBUS,  "unknown 16"                      },
+        { do_bad,               SIGBUS,  "unknown 17"                      },
+        { do_bad,               SIGBUS,  "unknown 18"                      },
+        { do_bad,               SIGBUS,  "unknown 19"                      },
+        { do_bad,               SIGBUS,  "lock abort"                      }, /* xscale */
+        { do_bad,               SIGBUS,  "unknown 21"                      },
+        { do_bad,               SIGBUS,  "imprecise external abort"        }, /* xscale */
+        { do_bad,               SIGBUS,  "unknown 23"                      },
+        { do_bad,               SIGBUS,  "dcache parity error"             }, /* xscale */
+        { do_bad,               SIGBUS,  "unknown 25"                      },
+        { do_bad,               SIGBUS,  "unknown 26"                      },
+        { do_bad,               SIGBUS,  "unknown 27"                      },
+        { do_bad,               SIGBUS,  "unknown 28"                      },
+        { do_bad,               SIGBUS,  "unknown 29"                      },
+        { do_bad,               SIGBUS,  "unknown 30"                      },
+        { do_bad,               SIGBUS,  "unknown 31"                      }
+};
+
+void __init
+hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
+                int sig, const char *name)
+{
+        if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) {
+                fsr_info[nr].fn   = fn;
+                fsr_info[nr].sig  = sig;
+                fsr_info[nr].name = name;
+        }
+}
+
+/*
+ * Dispatch a data abort to the relevant handler.
+ */
+asmlinkage void
+do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+        const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6);
+
+        if (!inf->fn(addr, fsr, regs))
+                return;
+
+        printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
+                inf->name, fsr, addr);
+        force_sig(inf->sig, current);
+        show_pte(current->mm, addr);
+        die_if_kernel("Oops", regs, 0);
+}
+
+asmlinkage void
+do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
+{
+        do_translation_fault(addr, 0, regs);
+}
+