| /* |
| * linux/arch/m68k/mm/fault.c |
| * |
| * Copyright (C) 1995 Hamish Macdonald |
| */ |
| |
| #include <linux/mman.h> |
| #include <linux/mm.h> |
| #include <linux/kernel.h> |
| #include <linux/ptrace.h> |
| #include <linux/interrupt.h> |
| #include <linux/module.h> |
| |
| #include <asm/setup.h> |
| #include <asm/traps.h> |
| #include <asm/uaccess.h> |
| #include <asm/pgalloc.h> |
| |
| extern void die_if_kernel(char *, struct pt_regs *, long); |
| |
| int send_fault_sig(struct pt_regs *regs) |
| { |
| siginfo_t siginfo = { 0, 0, 0, }; |
| |
| siginfo.si_signo = current->thread.signo; |
| siginfo.si_code = current->thread.code; |
| siginfo.si_addr = (void *)current->thread.faddr; |
| #ifdef DEBUG |
| printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code); |
| #endif |
| |
| if (user_mode(regs)) { |
| force_sig_info(siginfo.si_signo, |
| &siginfo, current); |
| } else { |
| if (handle_kernel_fault(regs)) |
| return -1; |
| |
| //if (siginfo.si_signo == SIGBUS) |
| // force_sig_info(siginfo.si_signo, |
| // &siginfo, current); |
| |
| /* |
| * Oops. The kernel tried to access some bad page. We'll have to |
| * terminate things with extreme prejudice. |
| */ |
| if ((unsigned long)siginfo.si_addr < PAGE_SIZE) |
| printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); |
| else |
| printk(KERN_ALERT "Unable to handle kernel access"); |
| printk(" at virtual address %p\n", siginfo.si_addr); |
| die_if_kernel("Oops", regs, 0 /*error_code*/); |
| do_exit(SIGKILL); |
| } |
| |
| return 1; |
| } |
| |
| /* |
| * This routine handles page faults. It determines the problem, and |
| * then passes it off to one of the appropriate routines. |
| * |
| * 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. |
| */ |
| int do_page_fault(struct pt_regs *regs, unsigned long address, |
| unsigned long error_code) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct * vma; |
| int fault; |
| unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
| |
| #ifdef DEBUG |
| printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", |
| regs->sr, regs->pc, address, error_code, mm ? mm->pgd : NULL); |
| #endif |
| |
| /* |
| * If we're in an interrupt or have no user |
| * context, we must not take the fault.. |
| */ |
| if (in_atomic() || !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 map_err; |
| if (vma->vm_flags & VM_IO) |
| goto acc_err; |
| if (vma->vm_start <= address) |
| goto good_area; |
| if (!(vma->vm_flags & VM_GROWSDOWN)) |
| goto map_err; |
| if (user_mode(regs)) { |
| /* Accessing the stack below usp is always a bug. The |
| "+ 256" is there due to some instructions doing |
| pre-decrement on the stack and that doesn't show up |
| until later. */ |
| if (address + 256 < rdusp()) |
| goto map_err; |
| } |
| if (expand_stack(vma, address)) |
| goto map_err; |
| |
| /* |
| * Ok, we have a good vm_area for this memory access, so |
| * we can handle it.. |
| */ |
| good_area: |
| #ifdef DEBUG |
| printk("do_page_fault: good_area\n"); |
| #endif |
| switch (error_code & 3) { |
| default: /* 3: write, present */ |
| /* fall through */ |
| case 2: /* write, not present */ |
| if (!(vma->vm_flags & VM_WRITE)) |
| goto acc_err; |
| flags |= FAULT_FLAG_WRITE; |
| break; |
| case 1: /* read, present */ |
| goto acc_err; |
| case 0: /* read, not present */ |
| if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
| goto acc_err; |
| } |
| |
| /* |
| * 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); |
| #ifdef DEBUG |
| printk("handle_mm_fault returns %d\n",fault); |
| #endif |
| |
| if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) |
| return 0; |
| |
| if (unlikely(fault & VM_FAULT_ERROR)) { |
| if (fault & VM_FAULT_OOM) |
| goto out_of_memory; |
| else if (fault & VM_FAULT_SIGBUS) |
| goto bus_err; |
| BUG(); |
| } |
| |
| /* |
| * Major/minor page fault accounting is only done on the |
| * initial attempt. If we go through a retry, it is extremely |
| * likely that the page will be found in page cache at that point. |
| */ |
| if (flags & FAULT_FLAG_ALLOW_RETRY) { |
| if (fault & VM_FAULT_MAJOR) |
| current->maj_flt++; |
| else |
| current->min_flt++; |
| if (fault & VM_FAULT_RETRY) { |
| /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk |
| * of starvation. */ |
| 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 0; |
| |
| /* |
| * 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 0; |
| |
| no_context: |
| current->thread.signo = SIGBUS; |
| current->thread.faddr = address; |
| return send_fault_sig(regs); |
| |
| bus_err: |
| current->thread.signo = SIGBUS; |
| current->thread.code = BUS_ADRERR; |
| current->thread.faddr = address; |
| goto send_sig; |
| |
| map_err: |
| current->thread.signo = SIGSEGV; |
| current->thread.code = SEGV_MAPERR; |
| current->thread.faddr = address; |
| goto send_sig; |
| |
| acc_err: |
| current->thread.signo = SIGSEGV; |
| current->thread.code = SEGV_ACCERR; |
| current->thread.faddr = address; |
| |
| send_sig: |
| up_read(&mm->mmap_sem); |
| return send_fault_sig(regs); |
| } |