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/uaccess.h>
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 */
bust_spinlocks(int yes)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
do_BUG(const char * file,int line)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 */
do_page_fault(struct pt_regs * regs,unsigned long fault_code,unsigned long address)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 write, fault;
127
128 #ifdef CONFIG_GDBSTUB
129 /* handle GDB stub causing a fault */
130 if (gdbstub_busy) {
131 gdbstub_exception(regs, TBR & TBR_INT_CODE);
132 return;
133 }
134 #endif
135
136 #if 0
137 printk(KERN_DEBUG "--- do_page_fault(%p,%s:%04lx,%08lx)\n",
138 regs,
139 fault_code & 0x10000 ? "ins" : "data",
140 fault_code & 0xffff, address);
141 #endif
142
143 tsk = current;
144
145 /*
146 * We fault-in kernel-space virtual memory on-demand. The
147 * 'reference' page table is init_mm.pgd.
148 *
149 * NOTE! We MUST NOT take any locks for this case. We may
150 * be in an interrupt or a critical region, and should
151 * only copy the information from the master page table,
152 * nothing more.
153 *
154 * This verifies that the fault happens in kernel space
155 * and that the fault was a page not present (invalid) error
156 */
157 if (address >= VMALLOC_START && address < VMALLOC_END &&
158 (fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR &&
159 (fault_code & MMUFCR_xFC_PGINVAL) == MMUFCR_xFC_PGINVAL
160 )
161 goto vmalloc_fault;
162
163 mm = tsk->mm;
164 info.si_code = SEGV_MAPERR;
165
166 /*
167 * If we're in an interrupt or have no user
168 * context, we must not take the fault..
169 */
170 if (in_atomic() || !mm)
171 goto no_context;
172
173 down_read(&mm->mmap_sem);
174
175 vma = find_vma(mm, address);
176 if (!vma)
177 goto bad_area;
178 if (vma->vm_start <= address)
179 goto good_area;
180 if (!(vma->vm_flags & VM_GROWSDOWN))
181 goto bad_area;
182
183 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
184 /* accessing the stack below the stack pointer is always a
185 * bug */
186 if ((address & PAGE_MASK) + 2 * PAGE_SIZE < regs->sp) {
187 #if 0
188 printk(KERN_WARNING
189 "[%d] ### Access below stack @%lx (sp=%lx)\n",
190 current->pid, address, regs->sp);
191 printk(KERN_WARNING
192 "vma [%08x - %08x]\n",
193 vma->vm_start, vma->vm_end);
194 show_registers(regs);
195 printk(KERN_WARNING
196 "[%d] ### Code: [%08lx]"
197 " %02x %02x %02x %02x %02x %02x %02x %02x\n",
198 current->pid,
199 regs->pc,
200 ((u8 *) regs->pc)[0],
201 ((u8 *) regs->pc)[1],
202 ((u8 *) regs->pc)[2],
203 ((u8 *) regs->pc)[3],
204 ((u8 *) regs->pc)[4],
205 ((u8 *) regs->pc)[5],
206 ((u8 *) regs->pc)[6],
207 ((u8 *) regs->pc)[7]
208 );
209 #endif
210 goto bad_area;
211 }
212 }
213
214 if (expand_stack(vma, address))
215 goto bad_area;
216
217 /*
218 * Ok, we have a good vm_area for this memory access, so
219 * we can handle it..
220 */
221 good_area:
222 info.si_code = SEGV_ACCERR;
223 write = 0;
224 switch (fault_code & (MMUFCR_xFC_PGINVAL|MMUFCR_xFC_TYPE)) {
225 default: /* 3: write, present */
226 case MMUFCR_xFC_TYPE_WRITE:
227 #ifdef TEST_VERIFY_AREA
228 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
229 printk(KERN_DEBUG "WP fault at %08lx\n", regs->pc);
230 #endif
231 /* write to absent page */
232 case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_WRITE:
233 if (!(vma->vm_flags & VM_WRITE))
234 goto bad_area;
235 write++;
236 break;
237
238 /* read from protected page */
239 case MMUFCR_xFC_TYPE_READ:
240 goto bad_area;
241
242 /* read from absent page present */
243 case MMUFCR_xFC_PGINVAL | MMUFCR_xFC_TYPE_READ:
244 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
245 goto bad_area;
246 break;
247 }
248
249 /*
250 * If for any reason at all we couldn't handle the fault,
251 * make sure we exit gracefully rather than endlessly redo
252 * the fault.
253 */
254 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
255 if (unlikely(fault & VM_FAULT_ERROR)) {
256 if (fault & VM_FAULT_OOM)
257 goto out_of_memory;
258 else if (fault & VM_FAULT_SIGBUS)
259 goto do_sigbus;
260 BUG();
261 }
262 if (fault & VM_FAULT_MAJOR)
263 current->maj_flt++;
264 else
265 current->min_flt++;
266
267 up_read(&mm->mmap_sem);
268 return;
269
270 /*
271 * Something tried to access memory that isn't in our memory map..
272 * Fix it, but check if it's kernel or user first..
273 */
274 bad_area:
275 up_read(&mm->mmap_sem);
276
277 /* User mode accesses just cause a SIGSEGV */
278 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR) {
279 info.si_signo = SIGSEGV;
280 info.si_errno = 0;
281 /* info.si_code has been set above */
282 info.si_addr = (void *)address;
283 force_sig_info(SIGSEGV, &info, tsk);
284 return;
285 }
286
287 no_context:
288 /* Are we prepared to handle this kernel fault? */
289 if (fixup_exception(regs))
290 return;
291
292 /*
293 * Oops. The kernel tried to access some bad page. We'll have to
294 * terminate things with extreme prejudice.
295 */
296
297 bust_spinlocks(1);
298
299 if (address < PAGE_SIZE)
300 printk(KERN_ALERT
301 "Unable to handle kernel NULL pointer dereference");
302 else
303 printk(KERN_ALERT
304 "Unable to handle kernel paging request");
305 printk(" at virtual address %08lx\n", address);
306 printk(" printing pc:\n");
307 printk(KERN_ALERT "%08lx\n", regs->pc);
308
309 debugger_intercept(fault_code & 0x00010000 ? EXCEP_IAERROR : EXCEP_DAERROR,
310 SIGSEGV, SEGV_ACCERR, regs);
311
312 page = PTBR;
313 page = ((unsigned long *) __va(page))[address >> 22];
314 printk(KERN_ALERT "*pde = %08lx\n", page);
315 if (page & 1) {
316 page &= PAGE_MASK;
317 address &= 0x003ff000;
318 page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
319 printk(KERN_ALERT "*pte = %08lx\n", page);
320 }
321
322 die("Oops", regs, fault_code);
323 do_exit(SIGKILL);
324
325 /*
326 * We ran out of memory, or some other thing happened to us that made
327 * us unable to handle the page fault gracefully.
328 */
329 out_of_memory:
330 up_read(&mm->mmap_sem);
331 printk(KERN_ALERT "VM: killing process %s\n", tsk->comm);
332 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_USR)
333 do_exit(SIGKILL);
334 goto no_context;
335
336 do_sigbus:
337 up_read(&mm->mmap_sem);
338
339 /*
340 * Send a sigbus, regardless of whether we were in kernel
341 * or user mode.
342 */
343 info.si_signo = SIGBUS;
344 info.si_errno = 0;
345 info.si_code = BUS_ADRERR;
346 info.si_addr = (void *)address;
347 force_sig_info(SIGBUS, &info, tsk);
348
349 /* Kernel mode? Handle exceptions or die */
350 if ((fault_code & MMUFCR_xFC_ACCESS) == MMUFCR_xFC_ACCESS_SR)
351 goto no_context;
352 return;
353
354 vmalloc_fault:
355 {
356 /*
357 * Synchronize this task's top level page-table
358 * with the 'reference' page table.
359 *
360 * Do _not_ use "tsk" here. We might be inside
361 * an interrupt in the middle of a task switch..
362 */
363 int index = pgd_index(address);
364 pgd_t *pgd, *pgd_k;
365 pud_t *pud, *pud_k;
366 pmd_t *pmd, *pmd_k;
367 pte_t *pte_k;
368
369 pgd_k = init_mm.pgd + index;
370
371 if (!pgd_present(*pgd_k))
372 goto no_context;
373
374 pud_k = pud_offset(pgd_k, address);
375 if (!pud_present(*pud_k))
376 goto no_context;
377
378 pmd_k = pmd_offset(pud_k, address);
379 if (!pmd_present(*pmd_k))
380 goto no_context;
381
382 pgd = (pgd_t *) PTBR + index;
383 pud = pud_offset(pgd, address);
384 pmd = pmd_offset(pud, address);
385 set_pmd(pmd, *pmd_k);
386
387 pte_k = pte_offset_kernel(pmd_k, address);
388 if (!pte_present(*pte_k))
389 goto no_context;
390 return;
391 }
392 }
393