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
27 #include <asm/system.h>
28 #include <asm/uaccess.h>
29 #include <asm/pgalloc.h>
30 #include <asm/hardirq.h>
31 #include <asm/cpu-regs.h>
32 #include <asm/debugger.h>
33 #include <asm/gdb-stub.h>
34
35 /*
36 * Unlock any spinlocks which will prevent us from getting the
37 * message out
38 */
bust_spinlocks(int yes)39 void bust_spinlocks(int yes)
40 {
41 if (yes) {
42 oops_in_progress = 1;
43 } else {
44 int loglevel_save = console_loglevel;
45 #ifdef CONFIG_VT
46 unblank_screen();
47 #endif
48 oops_in_progress = 0;
49 /*
50 * OK, the message is on the console. Now we call printk()
51 * without oops_in_progress set so that printk will give klogd
52 * a poke. Hold onto your hats...
53 */
54 console_loglevel = 15; /* NMI oopser may have shut the console
55 * up */
56 printk(" ");
57 console_loglevel = loglevel_save;
58 }
59 }
60
do_BUG(const char * file,int line)61 void do_BUG(const char *file, int line)
62 {
63 bust_spinlocks(1);
64 printk(KERN_EMERG "------------[ cut here ]------------\n");
65 printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
66 }
67
68 #if 0
69 static void print_pagetable_entries(pgd_t *pgdir, unsigned long address)
70 {
71 pgd_t *pgd;
72 pmd_t *pmd;
73 pte_t *pte;
74
75 pgd = pgdir + __pgd_offset(address);
76 printk(KERN_DEBUG "pgd entry %p: %016Lx\n",
77 pgd, (long long) pgd_val(*pgd));
78
79 if (!pgd_present(*pgd)) {
80 printk(KERN_DEBUG "... pgd not present!\n");
81 return;
82 }
83 pmd = pmd_offset(pgd, address);
84 printk(KERN_DEBUG "pmd entry %p: %016Lx\n",
85 pmd, (long long)pmd_val(*pmd));
86
87 if (!pmd_present(*pmd)) {
88 printk(KERN_DEBUG "... pmd not present!\n");
89 return;
90 }
91 pte = pte_offset(pmd, address);
92 printk(KERN_DEBUG "pte entry %p: %016Lx\n",
93 pte, (long long) pte_val(*pte));
94
95 if (!pte_present(*pte))
96 printk(KERN_DEBUG "... pte not present!\n");
97 }
98 #endif
99
100 /*
101 * This routine handles page faults. It determines the address,
102 * and the problem, and then passes it off to one of the appropriate
103 * routines.
104 *
105 * fault_code:
106 * - LSW: either MMUFCR_IFC or MMUFCR_DFC as appropriate
107 * - MSW: 0 if data access, 1 if instruction access
108 * - bit 0: TLB miss flag
109 * - bit 1: initial write
110 * - bit 2: page invalid
111 * - bit 3: protection violation
112 * - bit 4: accessor (0=user 1=kernel)
113 * - bit 5: 0=read 1=write
114 * - bit 6-8: page protection spec
115 * - bit 9: illegal address
116 * - bit 16: 0=data 1=ins
117 *
118 */
do_page_fault(struct pt_regs * regs,unsigned long fault_code,unsigned long address)119 asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long fault_code,
120 unsigned long address)
121 {
122 struct vm_area_struct *vma;
123 struct task_struct *tsk;
124 struct mm_struct *mm;
125 unsigned long page;
126 siginfo_t info;
127 int write, fault;
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 (in_atomic() || !mm)
172 goto no_context;
173
174 down_read(&mm->mmap_sem);
175
176 vma = find_vma(mm, address);
177 if (!vma)
178 goto bad_area;
179 if (vma->vm_start <= address)
180 goto good_area;
181 if (!(vma->vm_flags & VM_GROWSDOWN))
182 goto bad_area;
183
184 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
185 /* accessing the stack below the stack pointer is always a
186 * bug */
187 if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
188 #if 0
189 printk(KERN_WARNING
190 "[%d] ### Access below stack @%lx (sp=%lx)\n",
191 current->pid, address, regs->sp);
192 printk(KERN_WARNING
193 "vma [%08x - %08x]\n",
194 vma->vm_start, vma->vm_end);
195 show_registers(regs);
196 printk(KERN_WARNING
197 "[%d] ### Code: [%08lx]"
198 " %02x %02x %02x %02x %02x %02x %02x %02x\n",
199 current->pid,
200 regs->pc,
201 ((u8 *) regs->pc)[0],
202 ((u8 *) regs->pc)[1],
203 ((u8 *) regs->pc)[2],
204 ((u8 *) regs->pc)[3],
205 ((u8 *) regs->pc)[4],
206 ((u8 *) regs->pc)[5],
207 ((u8 *) regs->pc)[6],
208 ((u8 *) regs->pc)[7]
209 );
210 #endif
211 goto bad_area;
212 }
213 }
214
215 if (expand_stack(vma, address))
216 goto bad_area;
217
218 /*
219 * Ok, we have a good vm_area for this memory access, so
220 * we can handle it..
221 */
222 good_area:
223 info.si_code = SEGV_ACCERR;
224 write = 0;
225 switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
226 default: /* 3: write, present */
227 case MMUFCR_xFC_TYPE_WRITE:
228 #ifdef TEST_VERIFY_AREA
229 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
230 printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
231 #endif
232 /* write to absent page */
233 case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
234 if (!(vma->vm_flags & VM_WRITE))
235 goto bad_area;
236 write++;
237 break;
238
239 /* read from protected page */
240 case MMUFCR_xFC_TYPE_READ:
241 goto bad_area;
242
243 /* read from absent page present */
244 case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
245 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
246 goto bad_area;
247 break;
248 }
249
250 /*
251 * If for any reason at all we couldn't handle the fault,
252 * make sure we exit gracefully rather than endlessly redo
253 * the fault.
254 */
255 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
256 if (unlikely(fault & VM_FAULT_ERROR)) {
257 if (fault & VM_FAULT_OOM)
258 goto out_of_memory;
259 else if (fault & VM_FAULT_SIGBUS)
260 goto do_sigbus;
261 BUG();
262 }
263 if (fault & VM_FAULT_MAJOR)
264 current->maj_flt++;
265 else
266 current->min_flt++;
267
268 up_read(&mm->mmap_sem);
269 return;
270
271 /*
272 * Something tried to access memory that isn't in our memory map..
273 * Fix it, but check if it's kernel or user first..
274 */
275 bad_area:
276 up_read(&mm->mmap_sem);
277
278 /* User mode accesses just cause a SIGSEGV */
279 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
280 info.si_signo = SIGSEGV;
281 info.si_errno = 0;
282 /* info.si_code has been set above */
283 info.si_addr = (void *)address;
284 force_sig_info(SIGSEGV, &info, tsk);
285 return;
286 }
287
288 no_context:
289 /* Are we prepared to handle this kernel fault? */
290 if (fixup_exception(regs))
291 return;
292
293 /*
294 * Oops. The kernel tried to access some bad page. We'll have to
295 * terminate things with extreme prejudice.
296 */
297
298 bust_spinlocks(1);
299
300 if (address < PAGE_SIZE)
301 printk(KERN_ALERT
302 "Unable to handle kernel NULL pointer dereference");
303 else
304 printk(KERN_ALERT
305 "Unable to handle kernel paging request");
306 printk(" at virtual address %08lx\n", address);
307 printk(" printing pc:\n");
308 printk(KERN_ALERT "%08lx\n", regs->pc);
309
310 debugger_intercept(fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR,
311 SIGSEGV, SEGV_ACCERR, regs);
312
313 page = PTBR;
314 page = ((unsigned long *) __va(page))[address >> 22];
315 printk(KERN_ALERT "*pde = %08lx\n", page);
316 if (page & 1) {
317 page &= PAGE_MASK;
318 address &= 0x003ff000;
319 page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
320 printk(KERN_ALERT "*pte = %08lx\n", page);
321 }
322
323 die("Oops", regs, fault_code);
324 do_exit(SIGKILL);
325
326 /*
327 * We ran out of memory, or some other thing happened to us that made
328 * us unable to handle the page fault gracefully.
329 */
330 out_of_memory:
331 up_read(&mm->mmap_sem);
332 printk(KERN_ALERT "VM: killing process %s\n", tsk->comm);
333 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
334 do_exit(SIGKILL);
335 goto no_context;
336
337 do_sigbus:
338 up_read(&mm->mmap_sem);
339
340 /*
341 * Send a sigbus, regardless of whether we were in kernel
342 * or user mode.
343 */
344 info.si_signo = SIGBUS;
345 info.si_errno = 0;
346 info.si_code = BUS_ADRERR;
347 info.si_addr = (void *)address;
348 force_sig_info(SIGBUS, &info, tsk);
349
350 /* Kernel mode? Handle exceptions or die */
351 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
352 goto no_context;
353 return;
354
355 vmalloc_fault:
356 {
357 /*
358 * Synchronize this task's top level page-table
359 * with the 'reference' page table.
360 *
361 * Do _not_ use "tsk" here. We might be inside
362 * an interrupt in the middle of a task switch..
363 */
364 int index = pgd_index(address);
365 pgd_t *pgd, *pgd_k;
366 pud_t *pud, *pud_k;
367 pmd_t *pmd, *pmd_k;
368 pte_t *pte_k;
369
370 pgd_k = init_mm.pgd + index;
371
372 if (!pgd_present(*pgd_k))
373 goto no_context;
374
375 pud_k = pud_offset(pgd_k, address);
376 if (!pud_present(*pud_k))
377 goto no_context;
378
379 pmd_k = pmd_offset(pud_k, address);
380 if (!pmd_present(*pmd_k))
381 goto no_context;
382
383 pgd = (pgd_t *) PTBR + index;
384 pud = pud_offset(pgd, address);
385 pmd = pmd_offset(pud, address);
386 set_pmd(pmd, *pmd_k);
387
388 pte_k = pte_offset_kernel(pmd_k, address);
389 if (!pte_present(*pte_k))
390 goto no_context;
391 return;
392 }
393 }
394