Merge branch 'akpm' (Andrew's patch-bomb)
[linux-3.10.git] / arch / mips / mm / fault.c
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 1995 - 2000 by Ralf Baechle
7  */
8 #include <linux/signal.h>
9 #include <linux/sched.h>
10 #include <linux/interrupt.h>
11 #include <linux/kernel.h>
12 #include <linux/errno.h>
13 #include <linux/string.h>
14 #include <linux/types.h>
15 #include <linux/ptrace.h>
16 #include <linux/mman.h>
17 #include <linux/mm.h>
18 #include <linux/smp.h>
19 #include <linux/module.h>
20 #include <linux/kprobes.h>
21 #include <linux/perf_event.h>
22
23 #include <asm/branch.h>
24 #include <asm/mmu_context.h>
25 #include <asm/uaccess.h>
26 #include <asm/ptrace.h>
27 #include <asm/highmem.h>                /* For VMALLOC_END */
28 #include <linux/kdebug.h>
29
30 /*
31  * This routine handles page faults.  It determines the address,
32  * and the problem, and then passes it off to one of the appropriate
33  * routines.
34  */
35 asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long write,
36                               unsigned long address)
37 {
38         struct vm_area_struct * vma = NULL;
39         struct task_struct *tsk = current;
40         struct mm_struct *mm = tsk->mm;
41         const int field = sizeof(unsigned long) * 2;
42         siginfo_t info;
43         int fault;
44         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
45                                                  (write ? FAULT_FLAG_WRITE : 0);
46
47 #if 0
48         printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
49                current->comm, current->pid, field, address, write,
50                field, regs->cp0_epc);
51 #endif
52
53 #ifdef CONFIG_KPROBES
54         /*
55          * This is to notify the fault handler of the kprobes.  The
56          * exception code is redundant as it is also carried in REGS,
57          * but we pass it anyhow.
58          */
59         if (notify_die(DIE_PAGE_FAULT, "page fault", regs, -1,
60                        (regs->cp0_cause >> 2) & 0x1f, SIGSEGV) == NOTIFY_STOP)
61                 return;
62 #endif
63
64         info.si_code = SEGV_MAPERR;
65
66         /*
67          * We fault-in kernel-space virtual memory on-demand. The
68          * 'reference' page table is init_mm.pgd.
69          *
70          * NOTE! We MUST NOT take any locks for this case. We may
71          * be in an interrupt or a critical region, and should
72          * only copy the information from the master page table,
73          * nothing more.
74          */
75 #ifdef CONFIG_64BIT
76 # define VMALLOC_FAULT_TARGET no_context
77 #else
78 # define VMALLOC_FAULT_TARGET vmalloc_fault
79 #endif
80
81         if (unlikely(address >= VMALLOC_START && address <= VMALLOC_END))
82                 goto VMALLOC_FAULT_TARGET;
83 #ifdef MODULE_START
84         if (unlikely(address >= MODULE_START && address < MODULE_END))
85                 goto VMALLOC_FAULT_TARGET;
86 #endif
87
88         /*
89          * If we're in an interrupt or have no user
90          * context, we must not take the fault..
91          */
92         if (in_atomic() || !mm)
93                 goto bad_area_nosemaphore;
94
95 retry:
96         down_read(&mm->mmap_sem);
97         vma = find_vma(mm, address);
98         if (!vma)
99                 goto bad_area;
100         if (vma->vm_start <= address)
101                 goto good_area;
102         if (!(vma->vm_flags & VM_GROWSDOWN))
103                 goto bad_area;
104         if (expand_stack(vma, address))
105                 goto bad_area;
106 /*
107  * Ok, we have a good vm_area for this memory access, so
108  * we can handle it..
109  */
110 good_area:
111         info.si_code = SEGV_ACCERR;
112
113         if (write) {
114                 if (!(vma->vm_flags & VM_WRITE))
115                         goto bad_area;
116         } else {
117                 if (cpu_has_rixi) {
118                         if (address == regs->cp0_epc && !(vma->vm_flags & VM_EXEC)) {
119 #if 0
120                                 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] XI violation\n",
121                                           raw_smp_processor_id(),
122                                           current->comm, current->pid,
123                                           field, address, write,
124                                           field, regs->cp0_epc);
125 #endif
126                                 goto bad_area;
127                         }
128                         if (!(vma->vm_flags & VM_READ)) {
129 #if 0
130                                 pr_notice("Cpu%d[%s:%d:%0*lx:%ld:%0*lx] RI violation\n",
131                                           raw_smp_processor_id(),
132                                           current->comm, current->pid,
133                                           field, address, write,
134                                           field, regs->cp0_epc);
135 #endif
136                                 goto bad_area;
137                         }
138                 } else {
139                         if (!(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC)))
140                                 goto bad_area;
141                 }
142         }
143
144         /*
145          * If for any reason at all we couldn't handle the fault,
146          * make sure we exit gracefully rather than endlessly redo
147          * the fault.
148          */
149         fault = handle_mm_fault(mm, vma, address, flags);
150
151         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
152                 return;
153
154         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
155         if (unlikely(fault & VM_FAULT_ERROR)) {
156                 if (fault & VM_FAULT_OOM)
157                         goto out_of_memory;
158                 else if (fault & VM_FAULT_SIGBUS)
159                         goto do_sigbus;
160                 BUG();
161         }
162         if (flags & FAULT_FLAG_ALLOW_RETRY) {
163                 if (fault & VM_FAULT_MAJOR) {
164                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
165                                                   regs, address);
166                         tsk->maj_flt++;
167                 } else {
168                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
169                                                   regs, address);
170                         tsk->min_flt++;
171                 }
172                 if (fault & VM_FAULT_RETRY) {
173                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
174                         flags |= FAULT_FLAG_TRIED;
175
176                         /*
177                          * No need to up_read(&mm->mmap_sem) as we would
178                          * have already released it in __lock_page_or_retry
179                          * in mm/filemap.c.
180                          */
181
182                         goto retry;
183                 }
184         }
185
186         up_read(&mm->mmap_sem);
187         return;
188
189 /*
190  * Something tried to access memory that isn't in our memory map..
191  * Fix it, but check if it's kernel or user first..
192  */
193 bad_area:
194         up_read(&mm->mmap_sem);
195
196 bad_area_nosemaphore:
197         /* User mode accesses just cause a SIGSEGV */
198         if (user_mode(regs)) {
199                 tsk->thread.cp0_badvaddr = address;
200                 tsk->thread.error_code = write;
201 #if 0
202                 printk("do_page_fault() #2: sending SIGSEGV to %s for "
203                        "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
204                        tsk->comm,
205                        write ? "write access to" : "read access from",
206                        field, address,
207                        field, (unsigned long) regs->cp0_epc,
208                        field, (unsigned long) regs->regs[31]);
209 #endif
210                 info.si_signo = SIGSEGV;
211                 info.si_errno = 0;
212                 /* info.si_code has been set above */
213                 info.si_addr = (void __user *) address;
214                 force_sig_info(SIGSEGV, &info, tsk);
215                 return;
216         }
217
218 no_context:
219         /* Are we prepared to handle this kernel fault?  */
220         if (fixup_exception(regs)) {
221                 current->thread.cp0_baduaddr = address;
222                 return;
223         }
224
225         /*
226          * Oops. The kernel tried to access some bad page. We'll have to
227          * terminate things with extreme prejudice.
228          */
229         bust_spinlocks(1);
230
231         printk(KERN_ALERT "CPU %d Unable to handle kernel paging request at "
232                "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
233                raw_smp_processor_id(), field, address, field, regs->cp0_epc,
234                field,  regs->regs[31]);
235         die("Oops", regs);
236
237 out_of_memory:
238         /*
239          * We ran out of memory, call the OOM killer, and return the userspace
240          * (which will retry the fault, or kill us if we got oom-killed).
241          */
242         up_read(&mm->mmap_sem);
243         pagefault_out_of_memory();
244         return;
245
246 do_sigbus:
247         up_read(&mm->mmap_sem);
248
249         /* Kernel mode? Handle exceptions or die */
250         if (!user_mode(regs))
251                 goto no_context;
252         else
253         /*
254          * Send a sigbus, regardless of whether we were in kernel
255          * or user mode.
256          */
257 #if 0
258                 printk("do_page_fault() #3: sending SIGBUS to %s for "
259                        "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
260                        tsk->comm,
261                        write ? "write access to" : "read access from",
262                        field, address,
263                        field, (unsigned long) regs->cp0_epc,
264                        field, (unsigned long) regs->regs[31]);
265 #endif
266         tsk->thread.cp0_badvaddr = address;
267         info.si_signo = SIGBUS;
268         info.si_errno = 0;
269         info.si_code = BUS_ADRERR;
270         info.si_addr = (void __user *) address;
271         force_sig_info(SIGBUS, &info, tsk);
272
273         return;
274 #ifndef CONFIG_64BIT
275 vmalloc_fault:
276         {
277                 /*
278                  * Synchronize this task's top level page-table
279                  * with the 'reference' page table.
280                  *
281                  * Do _not_ use "tsk" here. We might be inside
282                  * an interrupt in the middle of a task switch..
283                  */
284                 int offset = __pgd_offset(address);
285                 pgd_t *pgd, *pgd_k;
286                 pud_t *pud, *pud_k;
287                 pmd_t *pmd, *pmd_k;
288                 pte_t *pte_k;
289
290                 pgd = (pgd_t *) pgd_current[raw_smp_processor_id()] + offset;
291                 pgd_k = init_mm.pgd + offset;
292
293                 if (!pgd_present(*pgd_k))
294                         goto no_context;
295                 set_pgd(pgd, *pgd_k);
296
297                 pud = pud_offset(pgd, address);
298                 pud_k = pud_offset(pgd_k, address);
299                 if (!pud_present(*pud_k))
300                         goto no_context;
301
302                 pmd = pmd_offset(pud, address);
303                 pmd_k = pmd_offset(pud_k, address);
304                 if (!pmd_present(*pmd_k))
305                         goto no_context;
306                 set_pmd(pmd, *pmd_k);
307
308                 pte_k = pte_offset_kernel(pmd_k, address);
309                 if (!pte_present(*pte_k))
310                         goto no_context;
311                 return;
312         }
313 #endif
314 }