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Linux/arch/sparc/mm/fault_32.c

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  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 
 25 #include <asm/page.h>
 26 #include <asm/pgtable.h>
 27 #include <asm/openprom.h>
 28 #include <asm/oplib.h>
 29 #include <asm/setup.h>
 30 #include <asm/smp.h>
 31 #include <asm/traps.h>
 32 #include <asm/uaccess.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 (in_atomic() || !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(mm, 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 __memset_start[];
307                         extern const unsigned __memset_end[];
308                         extern const unsigned __csum_partial_copy_start[];
309                         extern const unsigned __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(mm, 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 }
469 

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