415 lines
10 KiB
C
415 lines
10 KiB
C
/* MN10300 MMU Fault handler
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*
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* Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
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* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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* Modified by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/interrupt.h>
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#include <linux/init.h>
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#include <linux/vt_kern.h> /* For unblank_screen() */
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#include <asm/uaccess.h>
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#include <asm/pgalloc.h>
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#include <asm/hardirq.h>
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#include <asm/cpu-regs.h>
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#include <asm/debugger.h>
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#include <asm/gdb-stub.h>
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/*
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* Unlock any spinlocks which will prevent us from getting the
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* message out
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*/
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void bust_spinlocks(int yes)
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{
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if (yes) {
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oops_in_progress = 1;
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} else {
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int loglevel_save = console_loglevel;
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#ifdef CONFIG_VT
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unblank_screen();
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#endif
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oops_in_progress = 0;
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/*
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* OK, the message is on the console. Now we call printk()
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* without oops_in_progress set so that printk will give klogd
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* a poke. Hold onto your hats...
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*/
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console_loglevel = 15; /* NMI oopser may have shut the console
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* up */
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printk(" ");
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console_loglevel = loglevel_save;
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}
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}
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void do_BUG(const char *file, int line)
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{
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bust_spinlocks(1);
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printk(KERN_EMERG "------------[ cut here ]------------\n");
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printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
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}
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#if 0
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static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
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{
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pgd_t *pgd;
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pmd_t *pmd;
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pte_t *pte;
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pgd = pgdir + __pgd_offset(address);
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printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
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pgd, (long long) pgd_val(*pgd));
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if (!pgd_present(*pgd)) {
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printk(KERN_DEBUG "... pgd not present!\n");
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return;
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}
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pmd = pmd_offset(pgd, address);
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printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
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pmd, (long long)pmd_val(*pmd));
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if (!pmd_present(*pmd)) {
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printk(KERN_DEBUG "... pmd not present!\n");
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return;
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}
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pte = pte_offset(pmd, address);
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printk(KERN_DEBUG "pte entry %p: %016Lx\n",
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pte, (long long) pte_val(*pte));
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if (!pte_present(*pte))
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printk(KERN_DEBUG "... pte not present!\n");
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}
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#endif
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/*
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* This routine handles page faults. It determines the address,
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* and the problem, and then passes it off to one of the appropriate
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* routines.
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*
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* fault_code:
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* - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
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* - MSW: 0 if data access, 1 if instruction access
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* - bit 0: TLB miss flag
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* - bit 1: initial write
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* - bit 2: page invalid
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* - bit 3: protection violation
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* - bit 4: accessor (0=user 1=kernel)
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* - bit 5: 0=read 1=write
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* - bit 6-8: page protection spec
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* - bit 9: illegal address
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* - bit 16: 0=data 1=ins
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*
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*/
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asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
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unsigned long address)
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{
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struct vm_area_struct *vma;
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struct task_struct *tsk;
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struct mm_struct *mm;
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unsigned long page;
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siginfo_t info;
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int fault;
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unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
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#ifdef CONFIG_GDBSTUB
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/* handle GDB stub causing a fault */
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if (gdbstub_busy) {
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gdbstub_exception(regs, TBR & TBR_INT_CODE);
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return;
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}
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#endif
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#if 0
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printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n",
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regs,
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fault_code & 0x10000 ? "ins" : "data",
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fault_code & 0xffff, address);
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#endif
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tsk = current;
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/*
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* We fault-in kernel-space virtual memory on-demand. The
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* 'reference' page table is init_mm.pgd.
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*
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* NOTE! We MUST NOT take any locks for this case. We may
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* be in an interrupt or a critical region, and should
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* only copy the information from the master page table,
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* nothing more.
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*
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* This verifies that the fault happens in kernel space
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* and that the fault was a page not present (invalid) error
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*/
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if (address >= VMALLOC_START && address < VMALLOC_END &&
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(fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR &&
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(fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL
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)
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goto vmalloc_fault;
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mm = tsk->mm;
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info.si_code = SEGV_MAPERR;
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/*
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* If we're in an interrupt or have no user
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* context, we must not take the fault..
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*/
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if (in_atomic() || !mm)
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goto no_context;
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if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
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flags |= FAULT_FLAG_USER;
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retry:
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, address);
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if (!vma)
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goto bad_area;
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if (vma->vm_start <= address)
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goto good_area;
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if (!(vma->vm_flags & VM_GROWSDOWN))
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goto bad_area;
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if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
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/* accessing the stack below the stack pointer is always a
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* bug */
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if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
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#if 0
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printk(KERN_WARNING
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"[%d] ### Access below stack @%lx (sp=%lx)\n",
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current->pid, address, regs->sp);
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printk(KERN_WARNING
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"vma [%08x - %08x]\n",
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vma->vm_start, vma->vm_end);
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show_registers(regs);
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printk(KERN_WARNING
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"[%d] ### Code: [%08lx]"
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" %02x %02x %02x %02x %02x %02x %02x %02x\n",
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current->pid,
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regs->pc,
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((u8 *) regs->pc)[0],
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((u8 *) regs->pc)[1],
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((u8 *) regs->pc)[2],
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((u8 *) regs->pc)[3],
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((u8 *) regs->pc)[4],
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((u8 *) regs->pc)[5],
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((u8 *) regs->pc)[6],
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((u8 *) regs->pc)[7]
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);
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#endif
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goto bad_area;
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}
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}
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if (expand_stack(vma, address))
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goto bad_area;
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/*
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* Ok, we have a good vm_area for this memory access, so
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* we can handle it..
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*/
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good_area:
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info.si_code = SEGV_ACCERR;
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switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
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default: /* 3: write, present */
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case MMUFCR_xFC_TYPE_WRITE:
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#ifdef TEST_VERIFY_AREA
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if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
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printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
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#endif
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/* write to absent page */
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case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
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if (!(vma->vm_flags & VM_WRITE))
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goto bad_area;
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flags |= FAULT_FLAG_WRITE;
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break;
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/* read from protected page */
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case MMUFCR_xFC_TYPE_READ:
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goto bad_area;
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/* read from absent page present */
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case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
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if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
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goto bad_area;
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break;
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}
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/*
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* If for any reason at all we couldn't handle the fault,
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* make sure we exit gracefully rather than endlessly redo
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* the fault.
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*/
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fault = handle_mm_fault(mm, vma, address, flags);
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if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
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return;
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if (unlikely(fault & VM_FAULT_ERROR)) {
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if (fault & VM_FAULT_OOM)
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goto out_of_memory;
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else if (fault & VM_FAULT_SIGSEGV)
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goto bad_area;
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else if (fault & VM_FAULT_SIGBUS)
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goto do_sigbus;
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BUG();
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}
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if (flags & FAULT_FLAG_ALLOW_RETRY) {
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if (fault & VM_FAULT_MAJOR)
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current->maj_flt++;
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else
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current->min_flt++;
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if (fault & VM_FAULT_RETRY) {
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flags &= ~FAULT_FLAG_ALLOW_RETRY;
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/* No need to up_read(&mm->mmap_sem) as we would
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* have already released it in __lock_page_or_retry
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* in mm/filemap.c.
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*/
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goto retry;
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}
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}
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up_read(&mm->mmap_sem);
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return;
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/*
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* Something tried to access memory that isn't in our memory map..
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* Fix it, but check if it's kernel or user first..
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*/
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bad_area:
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up_read(&mm->mmap_sem);
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/* User mode accesses just cause a SIGSEGV */
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if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
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info.si_signo = SIGSEGV;
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info.si_errno = 0;
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/* info.si_code has been set above */
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info.si_addr = (void *)address;
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force_sig_info(SIGSEGV, &info, tsk);
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return;
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}
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no_context:
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/* Are we prepared to handle this kernel fault? */
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if (fixup_exception(regs))
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return;
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/*
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* Oops. The kernel tried to access some bad page. We'll have to
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* terminate things with extreme prejudice.
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*/
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bust_spinlocks(1);
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if (address < PAGE_SIZE)
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printk(KERN_ALERT
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"Unable to handle kernel NULL pointer dereference");
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else
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printk(KERN_ALERT
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"Unable to handle kernel paging request");
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printk(" at virtual address %08lx\n", address);
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printk(" printing pc:\n");
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printk(KERN_ALERT "%08lx\n", regs->pc);
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debugger_intercept(fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR,
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SIGSEGV, SEGV_ACCERR, regs);
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page = PTBR;
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page = ((unsigned long *) __va(page))[address >> 22];
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printk(KERN_ALERT "*pde = %08lx\n", page);
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if (page & 1) {
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page &= PAGE_MASK;
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address &= 0x003ff000;
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page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
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printk(KERN_ALERT "*pte = %08lx\n", page);
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}
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die("Oops", regs, fault_code);
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do_exit(SIGKILL);
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/*
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* We ran out of memory, or some other thing happened to us that made
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* us unable to handle the page fault gracefully.
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*/
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out_of_memory:
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up_read(&mm->mmap_sem);
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if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
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pagefault_out_of_memory();
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return;
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}
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goto no_context;
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do_sigbus:
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up_read(&mm->mmap_sem);
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/*
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* Send a sigbus, regardless of whether we were in kernel
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* or user mode.
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*/
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info.si_signo = SIGBUS;
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info.si_errno = 0;
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info.si_code = BUS_ADRERR;
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info.si_addr = (void *)address;
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force_sig_info(SIGBUS, &info, tsk);
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/* Kernel mode? Handle exceptions or die */
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if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
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goto no_context;
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return;
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vmalloc_fault:
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{
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/*
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* Synchronize this task's top level page-table
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* with the 'reference' page table.
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*
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* Do _not_ use "tsk" here. We might be inside
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* an interrupt in the middle of a task switch..
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*/
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int index = pgd_index(address);
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pgd_t *pgd, *pgd_k;
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pud_t *pud, *pud_k;
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pmd_t *pmd, *pmd_k;
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pte_t *pte_k;
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pgd_k = init_mm.pgd + index;
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if (!pgd_present(*pgd_k))
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goto no_context;
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pud_k = pud_offset(pgd_k, address);
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if (!pud_present(*pud_k))
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goto no_context;
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pmd_k = pmd_offset(pud_k, address);
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if (!pmd_present(*pmd_k))
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goto no_context;
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pgd = (pgd_t *) PTBR + index;
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pud = pud_offset(pgd, address);
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pmd = pmd_offset(pud, address);
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set_pmd(pmd, *pmd_k);
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pte_k = pte_offset_kernel(pmd_k, address);
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if (!pte_present(*pte_k))
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goto no_context;
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return;
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}
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}
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