GNU Linux-libre 4.9.296-gnu1
[releases.git] / arch / sparc / mm / fault_32.c
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/kdebug.h>
24 #include <linux/uaccess.h>
25
26 #include <asm/page.h>
27 #include <asm/pgtable.h>
28 #include <asm/openprom.h>
29 #include <asm/oplib.h>
30 #include <asm/setup.h>
31 #include <asm/smp.h>
32 #include <asm/traps.h>
33
34 #include "mm_32.h"
35
36 int show_unhandled_signals = 1;
37
38 static void __noreturn unhandled_fault(unsigned long address,
39                                        struct task_struct *tsk,
40                                        struct pt_regs *regs)
41 {
42         if ((unsigned long) address < PAGE_SIZE) {
43                 printk(KERN_ALERT
44                     "Unable to handle kernel NULL pointer dereference\n");
45         } else {
46                 printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
47                        address);
48         }
49         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
50                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
51         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
52                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
53                         (unsigned long) tsk->active_mm->pgd));
54         die_if_kernel("Oops", regs);
55 }
56
57 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
58                             unsigned long address)
59 {
60         struct pt_regs regs;
61         unsigned long g2;
62         unsigned int insn;
63         int i;
64
65         i = search_extables_range(ret_pc, &g2);
66         switch (i) {
67         case 3:
68                 /* load & store will be handled by fixup */
69                 return 3;
70
71         case 1:
72                 /* store will be handled by fixup, load will bump out */
73                 /* for _to_ macros */
74                 insn = *((unsigned int *) pc);
75                 if ((insn >> 21) & 1)
76                         return 1;
77                 break;
78
79         case 2:
80                 /* load will be handled by fixup, store will bump out */
81                 /* for _from_ macros */
82                 insn = *((unsigned int *) pc);
83                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
84                         return 2;
85                 break;
86
87         default:
88                 break;
89         }
90
91         memset(&regs, 0, sizeof(regs));
92         regs.pc = pc;
93         regs.npc = pc + 4;
94         __asm__ __volatile__(
95                 "rd %%psr, %0\n\t"
96                 "nop\n\t"
97                 "nop\n\t"
98                 "nop\n" : "=r" (regs.psr));
99         unhandled_fault(address, current, &regs);
100
101         /* Not reached */
102         return 0;
103 }
104
105 static inline void
106 show_signal_msg(struct pt_regs *regs, int sig, int code,
107                 unsigned long address, struct task_struct *tsk)
108 {
109         if (!unhandled_signal(tsk, sig))
110                 return;
111
112         if (!printk_ratelimit())
113                 return;
114
115         printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
116                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
117                tsk->comm, task_pid_nr(tsk), address,
118                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
119                (void *)regs->u_regs[UREG_FP], code);
120
121         print_vma_addr(KERN_CONT " in ", regs->pc);
122
123         printk(KERN_CONT "\n");
124 }
125
126 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
127                                unsigned long addr)
128 {
129         siginfo_t info;
130
131         info.si_signo = sig;
132         info.si_code = code;
133         info.si_errno = 0;
134         info.si_addr = (void __user *) addr;
135         info.si_trapno = 0;
136
137         if (unlikely(show_unhandled_signals))
138                 show_signal_msg(regs, sig, info.si_code,
139                                 addr, current);
140
141         force_sig_info (sig, &info, current);
142 }
143
144 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
145 {
146         unsigned int insn;
147
148         if (text_fault)
149                 return regs->pc;
150
151         if (regs->psr & PSR_PS)
152                 insn = *(unsigned int *) regs->pc;
153         else
154                 __get_user(insn, (unsigned int *) regs->pc);
155
156         return safe_compute_effective_address(regs, insn);
157 }
158
159 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
160                                       int text_fault)
161 {
162         unsigned long addr = compute_si_addr(regs, text_fault);
163
164         __do_fault_siginfo(code, sig, regs, addr);
165 }
166
167 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
168                                unsigned long address)
169 {
170         struct vm_area_struct *vma;
171         struct task_struct *tsk = current;
172         struct mm_struct *mm = tsk->mm;
173         unsigned int fixup;
174         unsigned long g2;
175         int from_user = !(regs->psr & PSR_PS);
176         int fault, code;
177         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
178
179         if (text_fault)
180                 address = regs->pc;
181
182         /*
183          * We fault-in kernel-space virtual memory on-demand. The
184          * 'reference' page table is init_mm.pgd.
185          *
186          * NOTE! We MUST NOT take any locks for this case. We may
187          * be in an interrupt or a critical region, and should
188          * only copy the information from the master page table,
189          * nothing more.
190          */
191         code = SEGV_MAPERR;
192         if (address >= TASK_SIZE)
193                 goto vmalloc_fault;
194
195         /*
196          * If we're in an interrupt or have no user
197          * context, we must not take the fault..
198          */
199         if (pagefault_disabled() || !mm)
200                 goto no_context;
201
202         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
203
204 retry:
205         down_read(&mm->mmap_sem);
206
207         if (!from_user && address >= PAGE_OFFSET)
208                 goto bad_area;
209
210         vma = find_vma(mm, address);
211         if (!vma)
212                 goto bad_area;
213         if (vma->vm_start <= address)
214                 goto good_area;
215         if (!(vma->vm_flags & VM_GROWSDOWN))
216                 goto bad_area;
217         if (expand_stack(vma, address))
218                 goto bad_area;
219         /*
220          * Ok, we have a good vm_area for this memory access, so
221          * we can handle it..
222          */
223 good_area:
224         code = SEGV_ACCERR;
225         if (write) {
226                 if (!(vma->vm_flags & VM_WRITE))
227                         goto bad_area;
228         } else {
229                 /* Allow reads even for write-only mappings */
230                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
231                         goto bad_area;
232         }
233
234         if (from_user)
235                 flags |= FAULT_FLAG_USER;
236         if (write)
237                 flags |= FAULT_FLAG_WRITE;
238
239         /*
240          * If for any reason at all we couldn't handle the fault,
241          * make sure we exit gracefully rather than endlessly redo
242          * the fault.
243          */
244         fault = handle_mm_fault(vma, address, flags);
245
246         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
247                 return;
248
249         if (unlikely(fault & VM_FAULT_ERROR)) {
250                 if (fault & VM_FAULT_OOM)
251                         goto out_of_memory;
252                 else if (fault & VM_FAULT_SIGSEGV)
253                         goto bad_area;
254                 else if (fault & VM_FAULT_SIGBUS)
255                         goto do_sigbus;
256                 BUG();
257         }
258
259         if (flags & FAULT_FLAG_ALLOW_RETRY) {
260                 if (fault & VM_FAULT_MAJOR) {
261                         current->maj_flt++;
262                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
263                                       1, regs, address);
264                 } else {
265                         current->min_flt++;
266                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
267                                       1, regs, address);
268                 }
269                 if (fault & VM_FAULT_RETRY) {
270                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
271                         flags |= FAULT_FLAG_TRIED;
272
273                         /* No need to up_read(&mm->mmap_sem) as we would
274                          * have already released it in __lock_page_or_retry
275                          * in mm/filemap.c.
276                          */
277
278                         goto retry;
279                 }
280         }
281
282         up_read(&mm->mmap_sem);
283         return;
284
285         /*
286          * Something tried to access memory that isn't in our memory map..
287          * Fix it, but check if it's kernel or user first..
288          */
289 bad_area:
290         up_read(&mm->mmap_sem);
291
292 bad_area_nosemaphore:
293         /* User mode accesses just cause a SIGSEGV */
294         if (from_user) {
295                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
296                 return;
297         }
298
299         /* Is this in ex_table? */
300 no_context:
301         g2 = regs->u_regs[UREG_G2];
302         if (!from_user) {
303                 fixup = search_extables_range(regs->pc, &g2);
304                 /* Values below 10 are reserved for other things */
305                 if (fixup > 10) {
306                         extern const unsigned int __memset_start[];
307                         extern const unsigned int __memset_end[];
308                         extern const unsigned int __csum_partial_copy_start[];
309                         extern const unsigned int __csum_partial_copy_end[];
310
311 #ifdef DEBUG_EXCEPTIONS
312                         printk("Exception: PC<%08lx> faddr<%08lx>\n",
313                                regs->pc, address);
314                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
315                                 regs->pc, fixup, g2);
316 #endif
317                         if ((regs->pc >= (unsigned long)__memset_start &&
318                              regs->pc < (unsigned long)__memset_end) ||
319                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
320                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
321                                 regs->u_regs[UREG_I4] = address;
322                                 regs->u_regs[UREG_I5] = regs->pc;
323                         }
324                         regs->u_regs[UREG_G2] = g2;
325                         regs->pc = fixup;
326                         regs->npc = regs->pc + 4;
327                         return;
328                 }
329         }
330
331         unhandled_fault(address, tsk, regs);
332         do_exit(SIGKILL);
333
334 /*
335  * We ran out of memory, or some other thing happened to us that made
336  * us unable to handle the page fault gracefully.
337  */
338 out_of_memory:
339         up_read(&mm->mmap_sem);
340         if (from_user) {
341                 pagefault_out_of_memory();
342                 return;
343         }
344         goto no_context;
345
346 do_sigbus:
347         up_read(&mm->mmap_sem);
348         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
349         if (!from_user)
350                 goto no_context;
351
352 vmalloc_fault:
353         {
354                 /*
355                  * Synchronize this task's top level page-table
356                  * with the 'reference' page table.
357                  */
358                 int offset = pgd_index(address);
359                 pgd_t *pgd, *pgd_k;
360                 pmd_t *pmd, *pmd_k;
361
362                 pgd = tsk->active_mm->pgd + offset;
363                 pgd_k = init_mm.pgd + offset;
364
365                 if (!pgd_present(*pgd)) {
366                         if (!pgd_present(*pgd_k))
367                                 goto bad_area_nosemaphore;
368                         pgd_val(*pgd) = pgd_val(*pgd_k);
369                         return;
370                 }
371
372                 pmd = pmd_offset(pgd, address);
373                 pmd_k = pmd_offset(pgd_k, address);
374
375                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
376                         goto bad_area_nosemaphore;
377
378                 *pmd = *pmd_k;
379                 return;
380         }
381 }
382
383 /* This always deals with user addresses. */
384 static void force_user_fault(unsigned long address, int write)
385 {
386         struct vm_area_struct *vma;
387         struct task_struct *tsk = current;
388         struct mm_struct *mm = tsk->mm;
389         unsigned int flags = FAULT_FLAG_USER;
390         int code;
391
392         code = SEGV_MAPERR;
393
394         down_read(&mm->mmap_sem);
395         vma = find_vma(mm, address);
396         if (!vma)
397                 goto bad_area;
398         if (vma->vm_start <= address)
399                 goto good_area;
400         if (!(vma->vm_flags & VM_GROWSDOWN))
401                 goto bad_area;
402         if (expand_stack(vma, address))
403                 goto bad_area;
404 good_area:
405         code = SEGV_ACCERR;
406         if (write) {
407                 if (!(vma->vm_flags & VM_WRITE))
408                         goto bad_area;
409                 flags |= FAULT_FLAG_WRITE;
410         } else {
411                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
412                         goto bad_area;
413         }
414         switch (handle_mm_fault(vma, address, flags)) {
415         case VM_FAULT_SIGBUS:
416         case VM_FAULT_OOM:
417                 goto do_sigbus;
418         }
419         up_read(&mm->mmap_sem);
420         return;
421 bad_area:
422         up_read(&mm->mmap_sem);
423         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
424         return;
425
426 do_sigbus:
427         up_read(&mm->mmap_sem);
428         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
429 }
430
431 static void check_stack_aligned(unsigned long sp)
432 {
433         if (sp & 0x7UL)
434                 force_sig(SIGILL, current);
435 }
436
437 void window_overflow_fault(void)
438 {
439         unsigned long sp;
440
441         sp = current_thread_info()->rwbuf_stkptrs[0];
442         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
443                 force_user_fault(sp + 0x38, 1);
444         force_user_fault(sp, 1);
445
446         check_stack_aligned(sp);
447 }
448
449 void window_underflow_fault(unsigned long sp)
450 {
451         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
452                 force_user_fault(sp + 0x38, 0);
453         force_user_fault(sp, 0);
454
455         check_stack_aligned(sp);
456 }
457
458 void window_ret_fault(struct pt_regs *regs)
459 {
460         unsigned long sp;
461
462         sp = regs->u_regs[UREG_FP];
463         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
464                 force_user_fault(sp + 0x38, 0);
465         force_user_fault(sp, 0);
466
467         check_stack_aligned(sp);
468 }