1 /*
2 * fault.c: Page fault handlers for the Sparc.
3 *
4 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
5 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
6 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
7 */
8
9 #include <asm/head.h>
10
11 #include <linux/string.h>
12 #include <linux/types.h>
13 #include <linux/sched.h>
14 #include <linux/ptrace.h>
15 #include <linux/mman.h>
16 #include <linux/threads.h>
17 #include <linux/kernel.h>
18 #include <linux/signal.h>
19 #include <linux/mm.h>
20 #include <linux/smp.h>
21 #include <linux/perf_event.h>
22 #include <linux/interrupt.h>
23 #include <linux/module.h>
24 #include <linux/kdebug.h>
25
26 #include <asm/system.h>
27 #include <asm/page.h>
28 #include <asm/pgtable.h>
29 #include <asm/memreg.h>
30 #include <asm/openprom.h>
31 #include <asm/oplib.h>
32 #include <asm/smp.h>
33 #include <asm/traps.h>
34 #include <asm/uaccess.h>
35
36 extern int prom_node_root;
37
38 int show_unhandled_signals = 1;
39
40 /* At boot time we determine these two values necessary for setting
41 * up the segment maps and page table entries (pte's).
42 */
43
44 int num_segmaps, num_contexts;
45 int invalid_segment;
46
47 /* various Virtual Address Cache parameters we find at boot time... */
48
49 int vac_size, vac_linesize, vac_do_hw_vac_flushes;
50 int vac_entries_per_context, vac_entries_per_segment;
51 int vac_entries_per_page;
52
53 /* Return how much physical memory we have. */
probe_memory(void)54 unsigned long probe_memory(void)
55 {
56 unsigned long total = 0;
57 int i;
58
59 for (i = 0; sp_banks[i].num_bytes; i++)
60 total += sp_banks[i].num_bytes;
61
62 return total;
63 }
64
65 extern void sun4c_complete_all_stores(void);
66
67 /* Whee, a level 15 NMI interrupt memory error. Let's have fun... */
sparc_lvl15_nmi(struct pt_regs * regs,unsigned long serr,unsigned long svaddr,unsigned long aerr,unsigned long avaddr)68 asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr,
69 unsigned long svaddr, unsigned long aerr,
70 unsigned long avaddr)
71 {
72 sun4c_complete_all_stores();
73 printk("FAULT: NMI received\n");
74 printk("SREGS: Synchronous Error %08lx\n", serr);
75 printk(" Synchronous Vaddr %08lx\n", svaddr);
76 printk(" Asynchronous Error %08lx\n", aerr);
77 printk(" Asynchronous Vaddr %08lx\n", avaddr);
78 if (sun4c_memerr_reg)
79 printk(" Memory Parity Error %08lx\n", *sun4c_memerr_reg);
80 printk("REGISTER DUMP:\n");
81 show_regs(regs);
82 prom_halt();
83 }
84
85 static void unhandled_fault(unsigned long, struct task_struct *,
86 struct pt_regs *) __attribute__ ((noreturn));
87
unhandled_fault(unsigned long address,struct task_struct * tsk,struct pt_regs * regs)88 static void unhandled_fault(unsigned long address, struct task_struct *tsk,
89 struct pt_regs *regs)
90 {
91 if((unsigned long) address < PAGE_SIZE) {
92 printk(KERN_ALERT
93 "Unable to handle kernel NULL pointer dereference\n");
94 } else {
95 printk(KERN_ALERT "Unable to handle kernel paging request "
96 "at virtual address %08lx\n", address);
97 }
98 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
99 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
100 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
101 (tsk->mm ? (unsigned long) tsk->mm->pgd :
102 (unsigned long) tsk->active_mm->pgd));
103 die_if_kernel("Oops", regs);
104 }
105
lookup_fault(unsigned long pc,unsigned long ret_pc,unsigned long address)106 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
107 unsigned long address)
108 {
109 struct pt_regs regs;
110 unsigned long g2;
111 unsigned int insn;
112 int i;
113
114 i = search_extables_range(ret_pc, &g2);
115 switch (i) {
116 case 3:
117 /* load & store will be handled by fixup */
118 return 3;
119
120 case 1:
121 /* store will be handled by fixup, load will bump out */
122 /* for _to_ macros */
123 insn = *((unsigned int *) pc);
124 if ((insn >> 21) & 1)
125 return 1;
126 break;
127
128 case 2:
129 /* load will be handled by fixup, store will bump out */
130 /* for _from_ macros */
131 insn = *((unsigned int *) pc);
132 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
133 return 2;
134 break;
135
136 default:
137 break;
138 };
139
140 memset(®s, 0, sizeof (regs));
141 regs.pc = pc;
142 regs.npc = pc + 4;
143 __asm__ __volatile__(
144 "rd %%psr, %0\n\t"
145 "nop\n\t"
146 "nop\n\t"
147 "nop\n" : "=r" (regs.psr));
148 unhandled_fault(address, current, ®s);
149
150 /* Not reached */
151 return 0;
152 }
153
154 static inline void
show_signal_msg(struct pt_regs * regs,int sig,int code,unsigned long address,struct task_struct * tsk)155 show_signal_msg(struct pt_regs *regs, int sig, int code,
156 unsigned long address, struct task_struct *tsk)
157 {
158 if (!unhandled_signal(tsk, sig))
159 return;
160
161 if (!printk_ratelimit())
162 return;
163
164 printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
165 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
166 tsk->comm, task_pid_nr(tsk), address,
167 (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
168 (void *)regs->u_regs[UREG_FP], code);
169
170 print_vma_addr(KERN_CONT " in ", regs->pc);
171
172 printk(KERN_CONT "\n");
173 }
174
__do_fault_siginfo(int code,int sig,struct pt_regs * regs,unsigned long addr)175 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
176 unsigned long addr)
177 {
178 siginfo_t info;
179
180 info.si_signo = sig;
181 info.si_code = code;
182 info.si_errno = 0;
183 info.si_addr = (void __user *) addr;
184 info.si_trapno = 0;
185
186 if (unlikely(show_unhandled_signals))
187 show_signal_msg(regs, sig, info.si_code,
188 addr, current);
189
190 force_sig_info (sig, &info, current);
191 }
192
193 extern unsigned long safe_compute_effective_address(struct pt_regs *,
194 unsigned int);
195
compute_si_addr(struct pt_regs * regs,int text_fault)196 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
197 {
198 unsigned int insn;
199
200 if (text_fault)
201 return regs->pc;
202
203 if (regs->psr & PSR_PS) {
204 insn = *(unsigned int *) regs->pc;
205 } else {
206 __get_user(insn, (unsigned int *) regs->pc);
207 }
208
209 return safe_compute_effective_address(regs, insn);
210 }
211
do_fault_siginfo(int code,int sig,struct pt_regs * regs,int text_fault)212 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
213 int text_fault)
214 {
215 unsigned long addr = compute_si_addr(regs, text_fault);
216
217 __do_fault_siginfo(code, sig, regs, addr);
218 }
219
do_sparc_fault(struct pt_regs * regs,int text_fault,int write,unsigned long address)220 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
221 unsigned long address)
222 {
223 struct vm_area_struct *vma;
224 struct task_struct *tsk = current;
225 struct mm_struct *mm = tsk->mm;
226 unsigned int fixup;
227 unsigned long g2;
228 int from_user = !(regs->psr & PSR_PS);
229 int fault, code;
230
231 if(text_fault)
232 address = regs->pc;
233
234 /*
235 * We fault-in kernel-space virtual memory on-demand. The
236 * 'reference' page table is init_mm.pgd.
237 *
238 * NOTE! We MUST NOT take any locks for this case. We may
239 * be in an interrupt or a critical region, and should
240 * only copy the information from the master page table,
241 * nothing more.
242 */
243 code = SEGV_MAPERR;
244 if (!ARCH_SUN4C && address >= TASK_SIZE)
245 goto vmalloc_fault;
246
247 /*
248 * If we're in an interrupt or have no user
249 * context, we must not take the fault..
250 */
251 if (in_atomic() || !mm)
252 goto no_context;
253
254 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address);
255
256 down_read(&mm->mmap_sem);
257
258 /*
259 * The kernel referencing a bad kernel pointer can lock up
260 * a sun4c machine completely, so we must attempt recovery.
261 */
262 if(!from_user && address >= PAGE_OFFSET)
263 goto bad_area;
264
265 vma = find_vma(mm, address);
266 if(!vma)
267 goto bad_area;
268 if(vma->vm_start <= address)
269 goto good_area;
270 if(!(vma->vm_flags & VM_GROWSDOWN))
271 goto bad_area;
272 if(expand_stack(vma, address))
273 goto bad_area;
274 /*
275 * Ok, we have a good vm_area for this memory access, so
276 * we can handle it..
277 */
278 good_area:
279 code = SEGV_ACCERR;
280 if(write) {
281 if(!(vma->vm_flags & VM_WRITE))
282 goto bad_area;
283 } else {
284 /* Allow reads even for write-only mappings */
285 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
286 goto bad_area;
287 }
288
289 /*
290 * If for any reason at all we couldn't handle the fault,
291 * make sure we exit gracefully rather than endlessly redo
292 * the fault.
293 */
294 fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
295 if (unlikely(fault & VM_FAULT_ERROR)) {
296 if (fault & VM_FAULT_OOM)
297 goto out_of_memory;
298 else if (fault & VM_FAULT_SIGBUS)
299 goto do_sigbus;
300 BUG();
301 }
302 if (fault & VM_FAULT_MAJOR) {
303 current->maj_flt++;
304 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
305 regs, address);
306 } else {
307 current->min_flt++;
308 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
309 regs, address);
310 }
311 up_read(&mm->mmap_sem);
312 return;
313
314 /*
315 * Something tried to access memory that isn't in our memory map..
316 * Fix it, but check if it's kernel or user first..
317 */
318 bad_area:
319 up_read(&mm->mmap_sem);
320
321 bad_area_nosemaphore:
322 /* User mode accesses just cause a SIGSEGV */
323 if (from_user) {
324 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
325 return;
326 }
327
328 /* Is this in ex_table? */
329 no_context:
330 g2 = regs->u_regs[UREG_G2];
331 if (!from_user) {
332 fixup = search_extables_range(regs->pc, &g2);
333 if (fixup > 10) { /* Values below are reserved for other things */
334 extern const unsigned __memset_start[];
335 extern const unsigned __memset_end[];
336 extern const unsigned __csum_partial_copy_start[];
337 extern const unsigned __csum_partial_copy_end[];
338
339 #ifdef DEBUG_EXCEPTIONS
340 printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address);
341 printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
342 regs->pc, fixup, g2);
343 #endif
344 if ((regs->pc >= (unsigned long)__memset_start &&
345 regs->pc < (unsigned long)__memset_end) ||
346 (regs->pc >= (unsigned long)__csum_partial_copy_start &&
347 regs->pc < (unsigned long)__csum_partial_copy_end)) {
348 regs->u_regs[UREG_I4] = address;
349 regs->u_regs[UREG_I5] = regs->pc;
350 }
351 regs->u_regs[UREG_G2] = g2;
352 regs->pc = fixup;
353 regs->npc = regs->pc + 4;
354 return;
355 }
356 }
357
358 unhandled_fault (address, tsk, regs);
359 do_exit(SIGKILL);
360
361 /*
362 * We ran out of memory, or some other thing happened to us that made
363 * us unable to handle the page fault gracefully.
364 */
365 out_of_memory:
366 up_read(&mm->mmap_sem);
367 if (from_user) {
368 pagefault_out_of_memory();
369 return;
370 }
371 goto no_context;
372
373 do_sigbus:
374 up_read(&mm->mmap_sem);
375 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
376 if (!from_user)
377 goto no_context;
378
379 vmalloc_fault:
380 {
381 /*
382 * Synchronize this task's top level page-table
383 * with the 'reference' page table.
384 */
385 int offset = pgd_index(address);
386 pgd_t *pgd, *pgd_k;
387 pmd_t *pmd, *pmd_k;
388
389 pgd = tsk->active_mm->pgd + offset;
390 pgd_k = init_mm.pgd + offset;
391
392 if (!pgd_present(*pgd)) {
393 if (!pgd_present(*pgd_k))
394 goto bad_area_nosemaphore;
395 pgd_val(*pgd) = pgd_val(*pgd_k);
396 return;
397 }
398
399 pmd = pmd_offset(pgd, address);
400 pmd_k = pmd_offset(pgd_k, address);
401
402 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
403 goto bad_area_nosemaphore;
404 *pmd = *pmd_k;
405 return;
406 }
407 }
408
do_sun4c_fault(struct pt_regs * regs,int text_fault,int write,unsigned long address)409 asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write,
410 unsigned long address)
411 {
412 extern void sun4c_update_mmu_cache(struct vm_area_struct *,
413 unsigned long,pte_t *);
414 extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long);
415 struct task_struct *tsk = current;
416 struct mm_struct *mm = tsk->mm;
417 pgd_t *pgdp;
418 pte_t *ptep;
419
420 if (text_fault) {
421 address = regs->pc;
422 } else if (!write &&
423 !(regs->psr & PSR_PS)) {
424 unsigned int insn, __user *ip;
425
426 ip = (unsigned int __user *)regs->pc;
427 if (!get_user(insn, ip)) {
428 if ((insn & 0xc1680000) == 0xc0680000)
429 write = 1;
430 }
431 }
432
433 if (!mm) {
434 /* We are oopsing. */
435 do_sparc_fault(regs, text_fault, write, address);
436 BUG(); /* P3 Oops already, you bitch */
437 }
438
439 pgdp = pgd_offset(mm, address);
440 ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address);
441
442 if (pgd_val(*pgdp)) {
443 if (write) {
444 if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT))
445 == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) {
446 unsigned long flags;
447
448 *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
449 _SUN4C_PAGE_MODIFIED |
450 _SUN4C_PAGE_VALID |
451 _SUN4C_PAGE_DIRTY);
452
453 local_irq_save(flags);
454 if (sun4c_get_segmap(address) != invalid_segment) {
455 sun4c_put_pte(address, pte_val(*ptep));
456 local_irq_restore(flags);
457 return;
458 }
459 local_irq_restore(flags);
460 }
461 } else {
462 if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT))
463 == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) {
464 unsigned long flags;
465
466 *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED |
467 _SUN4C_PAGE_VALID);
468
469 local_irq_save(flags);
470 if (sun4c_get_segmap(address) != invalid_segment) {
471 sun4c_put_pte(address, pte_val(*ptep));
472 local_irq_restore(flags);
473 return;
474 }
475 local_irq_restore(flags);
476 }
477 }
478 }
479
480 /* This conditional is 'interesting'. */
481 if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE))
482 && (pte_val(*ptep) & _SUN4C_PAGE_VALID))
483 /* Note: It is safe to not grab the MMAP semaphore here because
484 * we know that update_mmu_cache() will not sleep for
485 * any reason (at least not in the current implementation)
486 * and therefore there is no danger of another thread getting
487 * on the CPU and doing a shrink_mmap() on this vma.
488 */
489 sun4c_update_mmu_cache (find_vma(current->mm, address), address,
490 ptep);
491 else
492 do_sparc_fault(regs, text_fault, write, address);
493 }
494
495 /* This always deals with user addresses. */
force_user_fault(unsigned long address,int write)496 static void force_user_fault(unsigned long address, int write)
497 {
498 struct vm_area_struct *vma;
499 struct task_struct *tsk = current;
500 struct mm_struct *mm = tsk->mm;
501 int code;
502
503 code = SEGV_MAPERR;
504
505 down_read(&mm->mmap_sem);
506 vma = find_vma(mm, address);
507 if(!vma)
508 goto bad_area;
509 if(vma->vm_start <= address)
510 goto good_area;
511 if(!(vma->vm_flags & VM_GROWSDOWN))
512 goto bad_area;
513 if(expand_stack(vma, address))
514 goto bad_area;
515 good_area:
516 code = SEGV_ACCERR;
517 if(write) {
518 if(!(vma->vm_flags & VM_WRITE))
519 goto bad_area;
520 } else {
521 if(!(vma->vm_flags & (VM_READ | VM_EXEC)))
522 goto bad_area;
523 }
524 switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
525 case VM_FAULT_SIGBUS:
526 case VM_FAULT_OOM:
527 goto do_sigbus;
528 }
529 up_read(&mm->mmap_sem);
530 return;
531 bad_area:
532 up_read(&mm->mmap_sem);
533 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
534 return;
535
536 do_sigbus:
537 up_read(&mm->mmap_sem);
538 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
539 }
540
check_stack_aligned(unsigned long sp)541 static void check_stack_aligned(unsigned long sp)
542 {
543 if (sp & 0x7UL)
544 force_sig(SIGILL, current);
545 }
546
window_overflow_fault(void)547 void window_overflow_fault(void)
548 {
549 unsigned long sp;
550
551 sp = current_thread_info()->rwbuf_stkptrs[0];
552 if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
553 force_user_fault(sp + 0x38, 1);
554 force_user_fault(sp, 1);
555
556 check_stack_aligned(sp);
557 }
558
window_underflow_fault(unsigned long sp)559 void window_underflow_fault(unsigned long sp)
560 {
561 if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
562 force_user_fault(sp + 0x38, 0);
563 force_user_fault(sp, 0);
564
565 check_stack_aligned(sp);
566 }
567
window_ret_fault(struct pt_regs * regs)568 void window_ret_fault(struct pt_regs *regs)
569 {
570 unsigned long sp;
571
572 sp = regs->u_regs[UREG_FP];
573 if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
574 force_user_fault(sp + 0x38, 0);
575 force_user_fault(sp, 0);
576
577 check_stack_aligned(sp);
578 }
579