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Linux/arch/mn10300/mm/fault.c

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  1 /* MN10300 MMU Fault handler
  2  *
  3  * Copyright (C) 2007 Matsushita Electric Industrial Co., Ltd.
  4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  5  * Modified by David Howells (dhowells@redhat.com)
  6  *
  7  * This program is free software; you can redistribute it and/or
  8  * modify it under the terms of the GNU General Public Licence
  9  * as published by the Free Software Foundation; either version
 10  * 2 of the Licence, or (at your option) any later version.
 11  */
 12 
 13 #include <linux/signal.h>
 14 #include <linux/sched.h>
 15 #include <linux/kernel.h>
 16 #include <linux/errno.h>
 17 #include <linux/string.h>
 18 #include <linux/types.h>
 19 #include <linux/ptrace.h>
 20 #include <linux/mman.h>
 21 #include <linux/mm.h>
 22 #include <linux/smp.h>
 23 #include <linux/interrupt.h>
 24 #include <linux/init.h>
 25 #include <linux/vt_kern.h>              /* For unblank_screen() */
 26 #include <linux/uaccess.h>
 27 
 28 #include <asm/pgalloc.h>
 29 #include <asm/hardirq.h>
 30 #include <asm/cpu-regs.h>
 31 #include <asm/debugger.h>
 32 #include <asm/gdb-stub.h>
 33 
 34 /*
 35  * Unlock any spinlocks which will prevent us from getting the
 36  * message out
 37  */
 38 void bust_spinlocks(int yes)
 39 {
 40         if (yes) {
 41                 oops_in_progress = 1;
 42         } else {
 43                 int loglevel_save = console_loglevel;
 44 #ifdef CONFIG_VT
 45                 unblank_screen();
 46 #endif
 47                 oops_in_progress = 0;
 48                 /*
 49                  * OK, the message is on the console.  Now we call printk()
 50                  * without oops_in_progress set so that printk will give klogd
 51                  * a poke.  Hold onto your hats...
 52                  */
 53                 console_loglevel = 15;  /* NMI oopser may have shut the console
 54                                          * up */
 55                 printk(" ");
 56                 console_loglevel = loglevel_save;
 57         }
 58 }
 59 
 60 void do_BUG(const char *file, int line)
 61 {
 62         bust_spinlocks(1);
 63         printk(KERN_EMERG "------------[ cut here ]------------\n");
 64         printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
 65 }
 66 
 67 #if 0
 68 static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
 69 {
 70         pgd_t *pgd;
 71         pmd_t *pmd;
 72         pte_t *pte;
 73 
 74         pgd = pgdir + __pgd_offset(address);
 75         printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
 76                pgd, (long long) pgd_val(*pgd));
 77 
 78         if (!pgd_present(*pgd)) {
 79                 printk(KERN_DEBUG "... pgd not present!\n");
 80                 return;
 81         }
 82         pmd = pmd_offset(pgd, address);
 83         printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
 84                pmd, (long long)pmd_val(*pmd));
 85 
 86         if (!pmd_present(*pmd)) {
 87                 printk(KERN_DEBUG "... pmd not present!\n");
 88                 return;
 89         }
 90         pte = pte_offset(pmd, address);
 91         printk(KERN_DEBUG "pte entry %p: %016Lx\n",
 92                pte, (long long) pte_val(*pte));
 93 
 94         if (!pte_present(*pte))
 95                 printk(KERN_DEBUG "... pte not present!\n");
 96 }
 97 #endif
 98 
 99 /*
100  * This routine handles page faults.  It determines the address,
101  * and the problem, and then passes it off to one of the appropriate
102  * routines.
103  *
104  * fault_code:
105  * - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
106  * - MSW: 0 if data access, 1 if instruction access
107  * - bit 0: TLB miss flag
108  * - bit 1: initial write
109  * - bit 2: page invalid
110  * - bit 3: protection violation
111  * - bit 4: accessor (0=user 1=kernel)
112  * - bit 5: 0=read 1=write
113  * - bit 6-8: page protection spec
114  * - bit 9: illegal address
115  * - bit 16: 0=data 1=ins
116  *
117  */
118 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
119                               unsigned long address)
120 {
121         struct vm_area_struct *vma;
122         struct task_struct *tsk;
123         struct mm_struct *mm;
124         unsigned long page;
125         siginfo_t info;
126         int fault;
127         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
128 
129 #ifdef CONFIG_GDBSTUB
130         /* handle GDB stub causing a fault */
131         if (gdbstub_busy) {
132                 gdbstub_exception(regs, TBR & TBR_INT_CODE);
133                 return;
134         }
135 #endif
136 
137 #if 0
138         printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n",
139                regs,
140                fault_code & 0x10000 ? "ins" : "data",
141                fault_code & 0xffff, address);
142 #endif
143 
144         tsk = current;
145 
146         /*
147          * We fault-in kernel-space virtual memory on-demand. The
148          * 'reference' page table is init_mm.pgd.
149          *
150          * NOTE! We MUST NOT take any locks for this case. We may
151          * be in an interrupt or a critical region, and should
152          * only copy the information from the master page table,
153          * nothing more.
154          *
155          * This verifies that the fault happens in kernel space
156          * and that the fault was a page not present (invalid) error
157          */
158         if (address >= VMALLOC_START && address < VMALLOC_END &&
159             (fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR &&
160             (fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL
161             )
162                 goto vmalloc_fault;
163 
164         mm = tsk->mm;
165         info.si_code = SEGV_MAPERR;
166 
167         /*
168          * If we're in an interrupt or have no user
169          * context, we must not take the fault..
170          */
171         if (faulthandler_disabled() || !mm)
172                 goto no_context;
173 
174         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
175                 flags |= FAULT_FLAG_USER;
176 retry:
177         down_read(&mm->mmap_sem);
178 
179         vma = find_vma(mm, address);
180         if (!vma)
181                 goto bad_area;
182         if (vma->vm_start <= address)
183                 goto good_area;
184         if (!(vma->vm_flags & VM_GROWSDOWN))
185                 goto bad_area;
186 
187         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
188                 /* accessing the stack below the stack pointer is always a
189                  * bug */
190                 if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
191 #if 0
192                         printk(KERN_WARNING
193                                "[%d] ### Access below stack @%lx (sp=%lx)\n",
194                                current->pid, address, regs->sp);
195                         printk(KERN_WARNING
196                                "vma [%08x - %08x]\n",
197                                vma->vm_start, vma->vm_end);
198                         show_registers(regs);
199                         printk(KERN_WARNING
200                                "[%d] ### Code: [%08lx]"
201                                " %02x %02x %02x %02x %02x %02x %02x %02x\n",
202                                current->pid,
203                                regs->pc,
204                                ((u8 *) regs->pc)[0],
205                                ((u8 *) regs->pc)[1],
206                                ((u8 *) regs->pc)[2],
207                                ((u8 *) regs->pc)[3],
208                                ((u8 *) regs->pc)[4],
209                                ((u8 *) regs->pc)[5],
210                                ((u8 *) regs->pc)[6],
211                                ((u8 *) regs->pc)[7]
212                                );
213 #endif
214                         goto bad_area;
215                 }
216         }
217 
218         if (expand_stack(vma, address))
219                 goto bad_area;
220 
221 /*
222  * Ok, we have a good vm_area for this memory access, so
223  * we can handle it..
224  */
225 good_area:
226         info.si_code = SEGV_ACCERR;
227         switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
228         default:        /* 3: write, present */
229         case MMUFCR_xFC_TYPE_WRITE:
230 #ifdef TEST_VERIFY_AREA
231                 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
232                         printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
233 #endif
234                 /* write to absent page */
235         case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
236                 if (!(vma->vm_flags & VM_WRITE))
237                         goto bad_area;
238                 flags |= FAULT_FLAG_WRITE;
239                 break;
240 
241                 /* read from protected page */
242         case MMUFCR_xFC_TYPE_READ:
243                 goto bad_area;
244 
245                 /* read from absent page present */
246         case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
247                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
248                         goto bad_area;
249                 break;
250         }
251 
252         /*
253          * If for any reason at all we couldn't handle the fault,
254          * make sure we exit gracefully rather than endlessly redo
255          * the fault.
256          */
257         fault = handle_mm_fault(vma, address, flags);
258 
259         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
260                 return;
261 
262         if (unlikely(fault & VM_FAULT_ERROR)) {
263                 if (fault & VM_FAULT_OOM)
264                         goto out_of_memory;
265                 else if (fault & VM_FAULT_SIGSEGV)
266                         goto bad_area;
267                 else if (fault & VM_FAULT_SIGBUS)
268                         goto do_sigbus;
269                 BUG();
270         }
271         if (flags & FAULT_FLAG_ALLOW_RETRY) {
272                 if (fault & VM_FAULT_MAJOR)
273                         current->maj_flt++;
274                 else
275                         current->min_flt++;
276                 if (fault & VM_FAULT_RETRY) {
277                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
278 
279                          /* No need to up_read(&mm->mmap_sem) as we would
280                          * have already released it in __lock_page_or_retry
281                          * in mm/filemap.c.
282                          */
283 
284                         goto retry;
285                 }
286         }
287 
288         up_read(&mm->mmap_sem);
289         return;
290 
291 /*
292  * Something tried to access memory that isn't in our memory map..
293  * Fix it, but check if it's kernel or user first..
294  */
295 bad_area:
296         up_read(&mm->mmap_sem);
297 
298         /* User mode accesses just cause a SIGSEGV */
299         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
300                 info.si_signo = SIGSEGV;
301                 info.si_errno = 0;
302                 /* info.si_code has been set above */
303                 info.si_addr = (void *)address;
304                 force_sig_info(SIGSEGV, &info, tsk);
305                 return;
306         }
307 
308 no_context:
309         /* Are we prepared to handle this kernel fault?  */
310         if (fixup_exception(regs))
311                 return;
312 
313 /*
314  * Oops. The kernel tried to access some bad page. We'll have to
315  * terminate things with extreme prejudice.
316  */
317 
318         bust_spinlocks(1);
319 
320         if (address < PAGE_SIZE)
321                 printk(KERN_ALERT
322                        "Unable to handle kernel NULL pointer dereference");
323         else
324                 printk(KERN_ALERT
325                        "Unable to handle kernel paging request");
326         printk(" at virtual address %08lx\n", address);
327         printk(" printing pc:\n");
328         printk(KERN_ALERT "%08lx\n", regs->pc);
329 
330         debugger_intercept(fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR,
331                            SIGSEGV, SEGV_ACCERR, regs);
332 
333         page = PTBR;
334         page = ((unsigned long *) __va(page))[address >> 22];
335         printk(KERN_ALERT "*pde = %08lx\n", page);
336         if (page & 1) {
337                 page &= PAGE_MASK;
338                 address &= 0x003ff000;
339                 page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
340                 printk(KERN_ALERT "*pte = %08lx\n", page);
341         }
342 
343         die("Oops", regs, fault_code);
344         do_exit(SIGKILL);
345 
346 /*
347  * We ran out of memory, or some other thing happened to us that made
348  * us unable to handle the page fault gracefully.
349  */
350 out_of_memory:
351         up_read(&mm->mmap_sem);
352         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
353                 pagefault_out_of_memory();
354                 return;
355         }
356         goto no_context;
357 
358 do_sigbus:
359         up_read(&mm->mmap_sem);
360 
361         /*
362          * Send a sigbus, regardless of whether we were in kernel
363          * or user mode.
364          */
365         info.si_signo = SIGBUS;
366         info.si_errno = 0;
367         info.si_code = BUS_ADRERR;
368         info.si_addr = (void *)address;
369         force_sig_info(SIGBUS, &info, tsk);
370 
371         /* Kernel mode? Handle exceptions or die */
372         if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
373                 goto no_context;
374         return;
375 
376 vmalloc_fault:
377         {
378                 /*
379                  * Synchronize this task's top level page-table
380                  * with the 'reference' page table.
381                  *
382                  * Do _not_ use "tsk" here. We might be inside
383                  * an interrupt in the middle of a task switch..
384                  */
385                 int index = pgd_index(address);
386                 pgd_t *pgd, *pgd_k;
387                 pud_t *pud, *pud_k;
388                 pmd_t *pmd, *pmd_k;
389                 pte_t *pte_k;
390 
391                 pgd_k = init_mm.pgd + index;
392 
393                 if (!pgd_present(*pgd_k))
394                         goto no_context;
395 
396                 pud_k = pud_offset(pgd_k, address);
397                 if (!pud_present(*pud_k))
398                         goto no_context;
399 
400                 pmd_k = pmd_offset(pud_k, address);
401                 if (!pmd_present(*pmd_k))
402                         goto no_context;
403 
404                 pgd = (pgd_t *) PTBR + index;
405                 pud = pud_offset(pgd, address);
406                 pmd = pmd_offset(pud, address);
407                 set_pmd(pmd, *pmd_k);
408 
409                 pte_k = pte_offset_kernel(pmd_k, address);
410                 if (!pte_present(*pte_k))
411                         goto no_context;
412                 return;
413         }
414 }
415 

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