ia64/linux-2.6.18-xen.hg

view arch/arm26/mm/fault.c @ 647:a5bb490065f6

Fix the build after public header sync.
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Wed Aug 13 14:01:49 2008 +0100 (2008-08-13)
parents 831230e53067
children
line source
1 /*
2 * linux/arch/arm26/mm/fault.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 * Modifications for ARM processor (c) 1995-2001 Russell King
6 *
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.
10 */
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>
19 #include <linux/mm.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
28 #include "fault.h"
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))
41 #define DEBUG
42 /*
43 * This is useful to dump out the page tables associated with
44 * 'addr' in mm 'mm'.
45 */
46 void show_pte(struct mm_struct *mm, unsigned long addr)
47 {
48 pgd_t *pgd;
50 if (!mm)
51 mm = &init_mm;
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));
57 do {
58 pmd_t *pmd;
59 pte_t *pte;
61 pmd = pmd_offset(pgd, addr);
63 if (pmd_none(*pmd))
64 break;
66 if (pmd_bad(*pmd)) {
67 printk("(bad)");
68 break;
69 }
71 /* We must not map this if we have highmem enabled */
72 /* FIXME */
73 pte = pte_offset_map(pmd, addr);
74 printk(", *pte=%08lx", pte_val(*pte));
75 pte_unmap(pte);
76 } while(0);
78 printk("\n");
79 }
81 /*
82 * Oops. The kernel tried to access some page that wasn't present.
83 */
84 static void
85 __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
86 struct pt_regs *regs)
87 {
88 /*
89 * Are we prepared to handle this kernel fault?
90 */
91 if (fixup_exception(regs))
92 return;
94 /*
95 * No handler, we'll have to terminate things with extreme prejudice.
96 */
97 bust_spinlocks(1);
98 printk(KERN_ALERT
99 "Unable to handle kernel %s at virtual address %08lx\n",
100 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
101 "paging request", addr);
103 show_pte(mm, addr);
104 die("Oops", regs, fsr);
105 bust_spinlocks(0);
106 do_exit(SIGKILL);
107 }
109 /*
110 * Something tried to access memory that isn't in our memory map..
111 * User mode accesses just cause a SIGSEGV
112 */
113 static void
114 __do_user_fault(struct task_struct *tsk, unsigned long addr,
115 unsigned int fsr, int code, struct pt_regs *regs)
116 {
117 struct siginfo si;
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);
123 show_regs(regs);
124 //dump_backtrace(regs, tsk); // FIXME ARM32 dropped this - why?
125 while(1); //FIXME - hack to stop debug going nutso
126 #endif
128 tsk->thread.address = addr;
129 tsk->thread.error_code = fsr;
130 tsk->thread.trap_no = 14;
131 si.si_signo = SIGSEGV;
132 si.si_errno = 0;
133 si.si_code = code;
134 si.si_addr = (void *)addr;
135 force_sig_info(SIGSEGV, &si, tsk);
136 }
138 static int
139 __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
140 struct task_struct *tsk)
141 {
142 struct vm_area_struct *vma;
143 int fault, mask;
145 vma = find_vma(mm, addr);
146 fault = -2; /* bad map area */
147 if (!vma)
148 goto out;
149 if (vma->vm_start > addr)
150 goto check_stack;
152 /*
153 * Ok, we have a good vm_area for this
154 * memory access, so we can handle it.
155 */
156 good_area:
157 if (READ_FAULT(fsr)) /* read? */
158 mask = VM_READ|VM_EXEC;
159 else
160 mask = VM_WRITE;
162 fault = -1; /* bad access type */
163 if (!(vma->vm_flags & mask))
164 goto out;
166 /*
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.
170 */
171 survive:
172 fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, DO_COW(fsr));
174 /*
175 * Handle the "normal" cases first - successful and sigbus
176 */
177 switch (fault) {
178 case VM_FAULT_MAJOR:
179 tsk->maj_flt++;
180 return fault;
181 case VM_FAULT_MINOR:
182 tsk->min_flt++;
183 case VM_FAULT_SIGBUS:
184 return fault;
185 }
187 fault = -3; /* out of memory */
188 if (tsk->pid != 1)
189 goto out;
191 /*
192 * If we are out of memory for pid1,
193 * sleep for a while and retry
194 */
195 yield();
196 goto survive;
198 check_stack:
199 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
200 goto good_area;
201 out:
202 return fault;
203 }
205 int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
206 {
207 struct task_struct *tsk;
208 struct mm_struct *mm;
209 int fault;
211 tsk = current;
212 mm = tsk->mm;
214 /*
215 * If we're in an interrupt or have no user
216 * context, we must not take the fault..
217 */
218 if (in_interrupt() || !mm)
219 goto no_context;
221 down_read(&mm->mmap_sem);
222 fault = __do_page_fault(mm, addr, fsr, tsk);
223 up_read(&mm->mmap_sem);
225 /*
226 * Handle the "normal" case first
227 */
228 switch (fault) {
229 case VM_FAULT_MINOR:
230 case VM_FAULT_MAJOR:
231 return 0;
232 case VM_FAULT_SIGBUS:
233 goto do_sigbus;
234 }
236 /*
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?
240 */
241 if (!user_mode(regs)){
242 goto no_context;
243 }
245 if (fault == -3) {
246 /*
247 * We ran out of memory, or some other thing happened to
248 * us that made us unable to handle the page fault gracefully.
249 */
250 printk("VM: killing process %s\n", tsk->comm);
251 do_exit(SIGKILL);
252 }
253 else{
254 __do_user_fault(tsk, addr, fsr, fault == -1 ? SEGV_ACCERR : SEGV_MAPERR, regs);
255 }
257 return 0;
260 /*
261 * We ran out of memory, or some other thing happened to us that made
262 * us unable to handle the page fault gracefully.
263 */
264 do_sigbus:
265 /*
266 * Send a sigbus, regardless of whether we were in kernel
267 * or user mode.
268 */
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));
276 #endif
278 /* Kernel mode? Handle exceptions or die */
279 if (user_mode(regs))
280 return 0;
282 no_context:
283 __do_kernel_fault(mm, addr, fsr, regs);
284 return 0;
285 }
287 /*
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.
291 */
292 asmlinkage void
293 do_DataAbort(unsigned long min_addr, unsigned long max_addr, int mode, struct pt_regs *regs)
294 {
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);
299 }
300 }
302 asmlinkage int
303 do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
304 {
305 #if 0
306 if (the memc mapping for this page exists) {
307 printk ("Page in, but got abort (undefined instruction?)\n");
308 return 0;
309 }
310 #endif
311 do_page_fault(addr, FAULT_CODE_PREFETCH, regs);
312 return 1;
313 }