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