1 /* 2 * linux/arch/m68k/mm/fault.c 3 * 4 * Copyright (C) 1995 Hamish Macdonald 5 */ 6 7 #include <linux/mman.h> 8 #include <linux/mm.h> 9 #include <linux/kernel.h> 10 #include <linux/ptrace.h> 11 #include <linux/interrupt.h> 12 #include <linux/module.h> 13 14 #include <asm/setup.h> 15 #include <asm/traps.h> 16 #include <asm/uaccess.h> 17 #include <asm/pgalloc.h> 18 19 extern void die_if_kernel(char *, struct pt_regs *, long); 20 21 int send_fault_sig(struct pt_regs *regs) 22 { 23 siginfo_t siginfo = { 0, 0, 0, }; 24 25 siginfo.si_signo = current->thread.signo; 26 siginfo.si_code = current->thread.code; 27 siginfo.si_addr = (void *)current->thread.faddr; 28 #ifdef DEBUG 29 printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code); 30 #endif 31 32 if (user_mode(regs)) { 33 force_sig_info(siginfo.si_signo, 34 &siginfo, current); 35 } else { 36 if (handle_kernel_fault(regs)) 37 return -1; 38 39 //if (siginfo.si_signo == SIGBUS) 40 // force_sig_info(siginfo.si_signo, 41 // &siginfo, current); 42 43 /* 44 * Oops. The kernel tried to access some bad page. We'll have to 45 * terminate things with extreme prejudice. 46 */ 47 if ((unsigned long)siginfo.si_addr < PAGE_SIZE) 48 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); 49 else 50 printk(KERN_ALERT "Unable to handle kernel access"); 51 printk(" at virtual address %p\n", siginfo.si_addr); 52 die_if_kernel("Oops", regs, 0 /*error_code*/); 53 do_exit(SIGKILL); 54 } 55 56 return 1; 57 } 58 59 /* 60 * This routine handles page faults. It determines the problem, and 61 * then passes it off to one of the appropriate routines. 62 * 63 * error_code: 64 * bit 0 == 0 means no page found, 1 means protection fault 65 * bit 1 == 0 means read, 1 means write 66 * 67 * If this routine detects a bad access, it returns 1, otherwise it 68 * returns 0. 69 */ 70 int do_page_fault(struct pt_regs *regs, unsigned long address, 71 unsigned long error_code) 72 { 73 struct mm_struct *mm = current->mm; 74 struct vm_area_struct * vma; 75 int write, fault; 76 77 #ifdef DEBUG 78 printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", 79 regs->sr, regs->pc, address, error_code, 80 current->mm->pgd); 81 #endif 82 83 /* 84 * If we're in an interrupt or have no user 85 * context, we must not take the fault.. 86 */ 87 if (in_atomic() || !mm) 88 goto no_context; 89 90 down_read(&mm->mmap_sem); 91 92 vma = find_vma(mm, address); 93 if (!vma) 94 goto map_err; 95 if (vma->vm_flags & VM_IO) 96 goto acc_err; 97 if (vma->vm_start <= address) 98 goto good_area; 99 if (!(vma->vm_flags & VM_GROWSDOWN)) 100 goto map_err; 101 if (user_mode(regs)) { 102 /* Accessing the stack below usp is always a bug. The 103 "+ 256" is there due to some instructions doing 104 pre-decrement on the stack and that doesn't show up 105 until later. */ 106 if (address + 256 < rdusp()) 107 goto map_err; 108 } 109 if (expand_stack(vma, address)) 110 goto map_err; 111 112 /* 113 * Ok, we have a good vm_area for this memory access, so 114 * we can handle it.. 115 */ 116 good_area: 117 #ifdef DEBUG 118 printk("do_page_fault: good_area\n"); 119 #endif 120 write = 0; 121 switch (error_code & 3) { 122 default: /* 3: write, present */ 123 /* fall through */ 124 case 2: /* write, not present */ 125 if (!(vma->vm_flags & VM_WRITE)) 126 goto acc_err; 127 write++; 128 break; 129 case 1: /* read, present */ 130 goto acc_err; 131 case 0: /* read, not present */ 132 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) 133 goto acc_err; 134 } 135 136 /* 137 * If for any reason at all we couldn't handle the fault, 138 * make sure we exit gracefully rather than endlessly redo 139 * the fault. 140 */ 141 142 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0); 143 #ifdef DEBUG 144 printk("handle_mm_fault returns %d\n",fault); 145 #endif 146 if (unlikely(fault & VM_FAULT_ERROR)) { 147 if (fault & VM_FAULT_OOM) 148 goto out_of_memory; 149 else if (fault & VM_FAULT_SIGBUS) 150 goto bus_err; 151 BUG(); 152 } 153 if (fault & VM_FAULT_MAJOR) 154 current->maj_flt++; 155 else 156 current->min_flt++; 157 158 up_read(&mm->mmap_sem); 159 return 0; 160 161 /* 162 * We ran out of memory, or some other thing happened to us that made 163 * us unable to handle the page fault gracefully. 164 */ 165 out_of_memory: 166 up_read(&mm->mmap_sem); 167 if (!user_mode(regs)) 168 goto no_context; 169 pagefault_out_of_memory(); 170 return 0; 171 172 no_context: 173 current->thread.signo = SIGBUS; 174 current->thread.faddr = address; 175 return send_fault_sig(regs); 176 177 bus_err: 178 current->thread.signo = SIGBUS; 179 current->thread.code = BUS_ADRERR; 180 current->thread.faddr = address; 181 goto send_sig; 182 183 map_err: 184 current->thread.signo = SIGSEGV; 185 current->thread.code = SEGV_MAPERR; 186 current->thread.faddr = address; 187 goto send_sig; 188 189 acc_err: 190 current->thread.signo = SIGSEGV; 191 current->thread.code = SEGV_ACCERR; 192 current->thread.faddr = address; 193 194 send_sig: 195 up_read(&mm->mmap_sem); 196 return send_fault_sig(regs); 197 } 198