2 * linux/arch/m68k/mm/fault.c
4 * Copyright (C) 1995 Hamish Macdonald
7 #include <linux/mman.h>
9 #include <linux/kernel.h>
10 #include <linux/ptrace.h>
11 #include <linux/interrupt.h>
12 #include <linux/module.h>
14 #include <asm/setup.h>
15 #include <asm/traps.h>
16 #include <asm/uaccess.h>
17 #include <asm/pgalloc.h>
19 extern void die_if_kernel(char *, struct pt_regs *, long);
21 int send_fault_sig(struct pt_regs *regs)
23 siginfo_t siginfo = { 0, 0, 0, };
25 siginfo.si_signo = current->thread.signo;
26 siginfo.si_code = current->thread.code;
27 siginfo.si_addr = (void *)current->thread.faddr;
29 printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code);
32 if (user_mode(regs)) {
33 force_sig_info(siginfo.si_signo,
36 if (handle_kernel_fault(regs))
39 //if (siginfo.si_signo == SIGBUS)
40 // force_sig_info(siginfo.si_signo,
41 // &siginfo, current);
44 * Oops. The kernel tried to access some bad page. We'll have to
45 * terminate things with extreme prejudice.
47 if ((unsigned long)siginfo.si_addr < PAGE_SIZE)
48 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
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*/);
60 * This routine handles page faults. It determines the problem, and
61 * then passes it off to one of the appropriate routines.
64 * bit 0 == 0 means no page found, 1 means protection fault
65 * bit 1 == 0 means read, 1 means write
67 * If this routine detects a bad access, it returns 1, otherwise it
70 int do_page_fault(struct pt_regs *regs, unsigned long address,
71 unsigned long error_code)
73 struct mm_struct *mm = current->mm;
74 struct vm_area_struct * vma;
76 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
79 printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n",
80 regs->sr, regs->pc, address, error_code,
85 * If we're in an interrupt or have no user
86 * context, we must not take the fault..
88 if (in_atomic() || !mm)
92 flags |= FAULT_FLAG_USER;
94 down_read(&mm->mmap_sem);
96 vma = find_vma(mm, address);
99 if (vma->vm_flags & VM_IO)
101 if (vma->vm_start <= address)
103 if (!(vma->vm_flags & VM_GROWSDOWN))
105 if (user_mode(regs)) {
106 /* Accessing the stack below usp is always a bug. The
107 "+ 256" is there due to some instructions doing
108 pre-decrement on the stack and that doesn't show up
110 if (address + 256 < rdusp())
113 if (expand_stack(vma, address))
117 * Ok, we have a good vm_area for this memory access, so
122 printk("do_page_fault: good_area\n");
124 switch (error_code & 3) {
125 default: /* 3: write, present */
127 case 2: /* write, not present */
128 if (!(vma->vm_flags & VM_WRITE))
130 flags |= FAULT_FLAG_WRITE;
132 case 1: /* read, present */
134 case 0: /* read, not present */
135 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
140 * If for any reason at all we couldn't handle the fault,
141 * make sure we exit gracefully rather than endlessly redo
145 fault = handle_mm_fault(mm, vma, address, flags);
147 printk("handle_mm_fault returns %d\n",fault);
150 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
153 if (unlikely(fault & VM_FAULT_ERROR)) {
154 if (fault & VM_FAULT_OOM)
156 else if (fault & VM_FAULT_SIGBUS)
162 * Major/minor page fault accounting is only done on the
163 * initial attempt. If we go through a retry, it is extremely
164 * likely that the page will be found in page cache at that point.
166 if (flags & FAULT_FLAG_ALLOW_RETRY) {
167 if (fault & VM_FAULT_MAJOR)
171 if (fault & VM_FAULT_RETRY) {
172 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
174 flags &= ~FAULT_FLAG_ALLOW_RETRY;
175 flags |= FAULT_FLAG_TRIED;
178 * No need to up_read(&mm->mmap_sem) as we would
179 * have already released it in __lock_page_or_retry
187 up_read(&mm->mmap_sem);
191 * We ran out of memory, or some other thing happened to us that made
192 * us unable to handle the page fault gracefully.
195 up_read(&mm->mmap_sem);
196 if (!user_mode(regs))
198 pagefault_out_of_memory();
202 current->thread.signo = SIGBUS;
203 current->thread.faddr = address;
204 return send_fault_sig(regs);
207 current->thread.signo = SIGBUS;
208 current->thread.code = BUS_ADRERR;
209 current->thread.faddr = address;
213 current->thread.signo = SIGSEGV;
214 current->thread.code = SEGV_MAPERR;
215 current->thread.faddr = address;
219 current->thread.signo = SIGSEGV;
220 current->thread.code = SEGV_ACCERR;
221 current->thread.faddr = address;
224 up_read(&mm->mmap_sem);
225 return send_fault_sig(regs);