2 * linux/arch/arm26/mm/fault.c
4 * Copyright (C) 1995 Linus Torvalds
5 * Modifications for ARM processor (c) 1995-2001 Russell King
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 #include <linux/signal.h>
12 #include <linux/sched.h>
13 #include <linux/kernel.h>
14 #include <linux/errno.h>
15 #include <linux/string.h>
16 #include <linux/types.h>
17 #include <linux/ptrace.h>
18 #include <linux/mman.h>
20 #include <linux/interrupt.h>
21 #include <linux/proc_fs.h>
22 #include <linux/init.h>
24 #include <asm/system.h>
25 #include <asm/pgtable.h>
26 #include <asm/uaccess.h> //FIXME this header may be bogusly included
30 #define FAULT_CODE_LDRSTRPOST 0x80
31 #define FAULT_CODE_LDRSTRPRE 0x40
32 #define FAULT_CODE_LDRSTRREG 0x20
33 #define FAULT_CODE_LDMSTM 0x10
34 #define FAULT_CODE_LDCSTC 0x08
35 #define FAULT_CODE_PREFETCH 0x04
36 #define FAULT_CODE_WRITE 0x02
37 #define FAULT_CODE_FORCECOW 0x01
39 #define DO_COW(m) ((m) & (FAULT_CODE_WRITE|FAULT_CODE_FORCECOW))
40 #define READ_FAULT(m) (!((m) & FAULT_CODE_WRITE))
43 * This is useful to dump out the page tables associated with
46 void show_pte(struct mm_struct *mm, unsigned long addr)
53 printk(KERN_ALERT "pgd = %p\n", mm->pgd);
54 pgd = pgd_offset(mm, addr);
55 printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
61 pmd = pmd_offset(pgd, addr);
71 /* We must not map this if we have highmem enabled */
73 pte = pte_offset_map(pmd, addr);
74 printk(", *pte=%08lx", pte_val(*pte));
82 * Oops. The kernel tried to access some page that wasn't present.
85 __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
89 * Are we prepared to handle this kernel fault?
91 if (fixup_exception(regs))
95 * No handler, we'll have to terminate things with extreme prejudice.
99 "Unable to handle kernel %s at virtual address %08lx\n",
100 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
101 "paging request", addr);
104 die("Oops", regs, fsr);
110 * Something tried to access memory that isn't in our memory map..
111 * User mode accesses just cause a SIGSEGV
114 __do_user_fault(struct task_struct *tsk, unsigned long addr,
115 unsigned int fsr, int code, struct pt_regs *regs)
119 #ifdef CONFIG_DEBUG_USER
120 printk("%s: unhandled page fault at 0x%08lx, code 0x%03x\n",
121 tsk->comm, addr, fsr);
122 show_pte(tsk->mm, addr);
124 //dump_backtrace(regs, tsk); // FIXME ARM32 dropped this - why?
125 while(1); //FIXME - hack to stop debug going nutso
128 tsk->thread.address = addr;
129 tsk->thread.error_code = fsr;
130 tsk->thread.trap_no = 14;
131 si.si_signo = SIGSEGV;
134 si.si_addr = (void *)addr;
135 force_sig_info(SIGSEGV, &si, tsk);
139 __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
140 struct task_struct *tsk)
142 struct vm_area_struct *vma;
145 vma = find_vma(mm, addr);
146 fault = -2; /* bad map area */
149 if (vma->vm_start > addr)
153 * Ok, we have a good vm_area for this
154 * memory access, so we can handle it.
157 if (READ_FAULT(fsr)) /* read? */
158 mask = VM_READ|VM_EXEC|VM_WRITE;
162 fault = -1; /* bad access type */
163 if (!(vma->vm_flags & mask))
167 * If for any reason at all we couldn't handle
168 * the fault, make sure we exit gracefully rather
169 * than endlessly redo the fault.
172 fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, DO_COW(fsr));
175 * Handle the "normal" cases first - successful and sigbus
183 case VM_FAULT_SIGBUS:
187 fault = -3; /* out of memory */
192 * If we are out of memory for pid1,
193 * sleep for a while and retry
199 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
205 int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
207 struct task_struct *tsk;
208 struct mm_struct *mm;
215 * If we're in an interrupt or have no user
216 * context, we must not take the fault..
218 if (in_atomic() || !mm)
221 down_read(&mm->mmap_sem);
222 fault = __do_page_fault(mm, addr, fsr, tsk);
223 up_read(&mm->mmap_sem);
226 * Handle the "normal" case first
232 case VM_FAULT_SIGBUS:
237 * If we are in kernel mode at this point, we
238 * have no context to handle this fault with.
239 * FIXME - is this test right?
241 if (!user_mode(regs)){
247 * We ran out of memory, or some other thing happened to
248 * us that made us unable to handle the page fault gracefully.
250 printk("VM: killing process %s\n", tsk->comm);
254 __do_user_fault(tsk, addr, fsr, fault == -1 ? SEGV_ACCERR : SEGV_MAPERR, regs);
261 * We ran out of memory, or some other thing happened to us that made
262 * us unable to handle the page fault gracefully.
266 * Send a sigbus, regardless of whether we were in kernel
269 tsk->thread.address = addr; //FIXME - need other bits setting?
270 tsk->thread.error_code = fsr;
271 tsk->thread.trap_no = 14;
272 force_sig(SIGBUS, tsk);
273 #ifdef CONFIG_DEBUG_USER
274 printk(KERN_DEBUG "%s: sigbus at 0x%08lx, pc=0x%08lx\n",
275 current->comm, addr, instruction_pointer(regs));
278 /* Kernel mode? Handle exceptions or die */
283 __do_kernel_fault(mm, addr, fsr, regs);
288 * Handle a data abort. Note that we have to handle a range of addresses
289 * on ARM2/3 for ldm. If both pages are zero-mapped, then we have to force
290 * a copy-on-write. However, on the second page, we always force COW.
293 do_DataAbort(unsigned long min_addr, unsigned long max_addr, int mode, struct pt_regs *regs)
295 do_page_fault(min_addr, mode, regs);
297 if ((min_addr ^ max_addr) >> PAGE_SHIFT){
298 do_page_fault(max_addr, mode | FAULT_CODE_FORCECOW, regs);
303 do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
306 if (the memc mapping for this page exists) {
307 printk ("Page in, but got abort (undefined instruction?)\n");
311 do_page_fault(addr, FAULT_CODE_PREFETCH, regs);