316 lines
7.1 KiB
C
316 lines
7.1 KiB
C
/*
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* linux/arch/arm26/mm/fault.c
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*
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* Copyright (C) 1995 Linus Torvalds
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* Modifications for ARM processor (c) 1995-2001 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/config.h>
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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/interrupt.h>
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#include <linux/proc_fs.h>
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#include <linux/init.h>
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#include <asm/system.h>
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#include <asm/pgtable.h>
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#include <asm/uaccess.h> //FIXME this header may be bogusly included
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#include "fault.h"
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#define FAULT_CODE_LDRSTRPOST 0x80
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#define FAULT_CODE_LDRSTRPRE 0x40
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#define FAULT_CODE_LDRSTRREG 0x20
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#define FAULT_CODE_LDMSTM 0x10
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#define FAULT_CODE_LDCSTC 0x08
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#define FAULT_CODE_PREFETCH 0x04
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#define FAULT_CODE_WRITE 0x02
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#define FAULT_CODE_FORCECOW 0x01
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#define DO_COW(m) ((m) & (FAULT_CODE_WRITE|FAULT_CODE_FORCECOW))
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#define READ_FAULT(m) (!((m) & FAULT_CODE_WRITE))
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#define DEBUG
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/*
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* This is useful to dump out the page tables associated with
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* 'addr' in mm 'mm'.
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*/
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void show_pte(struct mm_struct *mm, unsigned long addr)
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{
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pgd_t *pgd;
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if (!mm)
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mm = &init_mm;
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printk(KERN_ALERT "pgd = %p\n", mm->pgd);
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pgd = pgd_offset(mm, addr);
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printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
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do {
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pmd_t *pmd;
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pte_t *pte;
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pmd = pmd_offset(pgd, addr);
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if (pmd_none(*pmd))
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break;
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if (pmd_bad(*pmd)) {
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printk("(bad)");
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break;
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}
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/* We must not map this if we have highmem enabled */
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/* FIXME */
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pte = pte_offset_map(pmd, addr);
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printk(", *pte=%08lx", pte_val(*pte));
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pte_unmap(pte);
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} while(0);
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printk("\n");
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}
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/*
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* Oops. The kernel tried to access some page that wasn't present.
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*/
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static void
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__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
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struct pt_regs *regs)
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{
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/*
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* Are we prepared to handle this kernel fault?
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*/
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if (fixup_exception(regs))
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return;
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/*
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* No handler, we'll have to terminate things with extreme prejudice.
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*/
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bust_spinlocks(1);
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printk(KERN_ALERT
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"Unable to handle kernel %s at virtual address %08lx\n",
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(addr < PAGE_SIZE) ? "NULL pointer dereference" :
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"paging request", addr);
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show_pte(mm, addr);
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die("Oops", regs, fsr);
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bust_spinlocks(0);
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do_exit(SIGKILL);
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}
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/*
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* Something tried to access memory that isn't in our memory map..
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* User mode accesses just cause a SIGSEGV
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*/
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static void
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__do_user_fault(struct task_struct *tsk, unsigned long addr,
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unsigned int fsr, int code, struct pt_regs *regs)
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{
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struct siginfo si;
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#ifdef CONFIG_DEBUG_USER
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printk("%s: unhandled page fault at 0x%08lx, code 0x%03x\n",
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tsk->comm, addr, fsr);
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show_pte(tsk->mm, addr);
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show_regs(regs);
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//dump_backtrace(regs, tsk); // FIXME ARM32 dropped this - why?
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while(1); //FIXME - hack to stop debug going nutso
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#endif
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tsk->thread.address = addr;
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tsk->thread.error_code = fsr;
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tsk->thread.trap_no = 14;
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si.si_signo = SIGSEGV;
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si.si_errno = 0;
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si.si_code = code;
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si.si_addr = (void *)addr;
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force_sig_info(SIGSEGV, &si, tsk);
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}
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static int
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__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
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struct task_struct *tsk)
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{
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struct vm_area_struct *vma;
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int fault, mask;
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vma = find_vma(mm, addr);
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fault = -2; /* bad map area */
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if (!vma)
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goto out;
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if (vma->vm_start > addr)
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goto check_stack;
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/*
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* Ok, we have a good vm_area for this
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* memory access, so we can handle it.
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*/
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good_area:
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if (READ_FAULT(fsr)) /* read? */
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mask = VM_READ|VM_EXEC;
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else
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mask = VM_WRITE;
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fault = -1; /* bad access type */
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if (!(vma->vm_flags & mask))
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goto out;
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/*
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* If for any reason at all we couldn't handle
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* the fault, make sure we exit gracefully rather
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* than endlessly redo the fault.
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*/
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survive:
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fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, DO_COW(fsr));
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/*
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* Handle the "normal" cases first - successful and sigbus
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*/
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switch (fault) {
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case VM_FAULT_MAJOR:
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tsk->maj_flt++;
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return fault;
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case VM_FAULT_MINOR:
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tsk->min_flt++;
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case VM_FAULT_SIGBUS:
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return fault;
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}
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fault = -3; /* out of memory */
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if (tsk->pid != 1)
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goto out;
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/*
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* If we are out of memory for pid1,
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* sleep for a while and retry
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*/
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yield();
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goto survive;
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check_stack:
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if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
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goto good_area;
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out:
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return fault;
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}
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int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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{
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struct task_struct *tsk;
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struct mm_struct *mm;
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int fault;
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tsk = current;
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mm = tsk->mm;
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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_interrupt() || !mm)
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goto no_context;
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down_read(&mm->mmap_sem);
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fault = __do_page_fault(mm, addr, fsr, tsk);
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up_read(&mm->mmap_sem);
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/*
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* Handle the "normal" case first
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*/
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switch (fault) {
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case VM_FAULT_MINOR:
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case VM_FAULT_MAJOR:
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return 0;
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case VM_FAULT_SIGBUS:
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goto do_sigbus;
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}
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/*
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* If we are in kernel mode at this point, we
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* have no context to handle this fault with.
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* FIXME - is this test right?
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*/
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if (!user_mode(regs)){
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goto no_context;
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}
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if (fault == -3) {
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/*
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* We ran out of memory, or some other thing happened to
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* us that made us unable to handle the page fault gracefully.
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*/
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printk("VM: killing process %s\n", tsk->comm);
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do_exit(SIGKILL);
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}
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else{
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__do_user_fault(tsk, addr, fsr, fault == -1 ? SEGV_ACCERR : SEGV_MAPERR, regs);
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}
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return 0;
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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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do_sigbus:
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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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tsk->thread.address = addr; //FIXME - need other bits setting?
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tsk->thread.error_code = fsr;
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tsk->thread.trap_no = 14;
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force_sig(SIGBUS, tsk);
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#ifdef CONFIG_DEBUG_USER
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printk(KERN_DEBUG "%s: sigbus at 0x%08lx, pc=0x%08lx\n",
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current->comm, addr, instruction_pointer(regs));
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#endif
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/* Kernel mode? Handle exceptions or die */
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if (user_mode(regs))
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return 0;
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no_context:
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__do_kernel_fault(mm, addr, fsr, regs);
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return 0;
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}
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/*
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* Handle a data abort. Note that we have to handle a range of addresses
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* on ARM2/3 for ldm. If both pages are zero-mapped, then we have to force
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* a copy-on-write. However, on the second page, we always force COW.
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*/
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asmlinkage void
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do_DataAbort(unsigned long min_addr, unsigned long max_addr, int mode, struct pt_regs *regs)
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{
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do_page_fault(min_addr, mode, regs);
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if ((min_addr ^ max_addr) >> PAGE_SHIFT){
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do_page_fault(max_addr, mode | FAULT_CODE_FORCECOW, regs);
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}
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}
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asmlinkage int
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do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
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{
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#if 0
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if (the memc mapping for this page exists) {
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printk ("Page in, but got abort (undefined instruction?)\n");
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return 0;
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}
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#endif
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do_page_fault(addr, FAULT_CODE_PREFETCH, regs);
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return 1;
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}
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