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Linux/arch/sparc/mm/fault_32.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * fault.c:  Page fault handlers for the Sparc.
  4  *
  5  * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
  6  * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
  7  * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
  8  */
  9 
 10 #include <asm/head.h>
 11 
 12 #include <linux/string.h>
 13 #include <linux/types.h>
 14 #include <linux/sched.h>
 15 #include <linux/ptrace.h>
 16 #include <linux/mman.h>
 17 #include <linux/threads.h>
 18 #include <linux/kernel.h>
 19 #include <linux/signal.h>
 20 #include <linux/mm.h>
 21 #include <linux/smp.h>
 22 #include <linux/perf_event.h>
 23 #include <linux/interrupt.h>
 24 #include <linux/kdebug.h>
 25 #include <linux/uaccess.h>
 26 
 27 #include <asm/page.h>
 28 #include <asm/pgtable.h>
 29 #include <asm/openprom.h>
 30 #include <asm/oplib.h>
 31 #include <asm/setup.h>
 32 #include <asm/smp.h>
 33 #include <asm/traps.h>
 34 
 35 #include "mm_32.h"
 36 
 37 int show_unhandled_signals = 1;
 38 
 39 static void __noreturn unhandled_fault(unsigned long address,
 40                                        struct task_struct *tsk,
 41                                        struct pt_regs *regs)
 42 {
 43         if ((unsigned long) address < PAGE_SIZE) {
 44                 printk(KERN_ALERT
 45                     "Unable to handle kernel NULL pointer dereference\n");
 46         } else {
 47                 printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
 48                        address);
 49         }
 50         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
 51                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
 52         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
 53                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
 54                         (unsigned long) tsk->active_mm->pgd));
 55         die_if_kernel("Oops", regs);
 56 }
 57 
 58 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
 59                             unsigned long address)
 60 {
 61         struct pt_regs regs;
 62         unsigned long g2;
 63         unsigned int insn;
 64         int i;
 65 
 66         i = search_extables_range(ret_pc, &g2);
 67         switch (i) {
 68         case 3:
 69                 /* load & store will be handled by fixup */
 70                 return 3;
 71 
 72         case 1:
 73                 /* store will be handled by fixup, load will bump out */
 74                 /* for _to_ macros */
 75                 insn = *((unsigned int *) pc);
 76                 if ((insn >> 21) & 1)
 77                         return 1;
 78                 break;
 79 
 80         case 2:
 81                 /* load will be handled by fixup, store will bump out */
 82                 /* for _from_ macros */
 83                 insn = *((unsigned int *) pc);
 84                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
 85                         return 2;
 86                 break;
 87 
 88         default:
 89                 break;
 90         }
 91 
 92         memset(&regs, 0, sizeof(regs));
 93         regs.pc = pc;
 94         regs.npc = pc + 4;
 95         __asm__ __volatile__(
 96                 "rd %%psr, %0\n\t"
 97                 "nop\n\t"
 98                 "nop\n\t"
 99                 "nop\n" : "=r" (regs.psr));
100         unhandled_fault(address, current, &regs);
101 
102         /* Not reached */
103         return 0;
104 }
105 
106 static inline void
107 show_signal_msg(struct pt_regs *regs, int sig, int code,
108                 unsigned long address, struct task_struct *tsk)
109 {
110         if (!unhandled_signal(tsk, sig))
111                 return;
112 
113         if (!printk_ratelimit())
114                 return;
115 
116         printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
117                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
118                tsk->comm, task_pid_nr(tsk), address,
119                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
120                (void *)regs->u_regs[UREG_FP], code);
121 
122         print_vma_addr(KERN_CONT " in ", regs->pc);
123 
124         printk(KERN_CONT "\n");
125 }
126 
127 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
128                                unsigned long addr)
129 {
130         siginfo_t info;
131 
132         info.si_signo = sig;
133         info.si_code = code;
134         info.si_errno = 0;
135         info.si_addr = (void __user *) addr;
136         info.si_trapno = 0;
137 
138         if (unlikely(show_unhandled_signals))
139                 show_signal_msg(regs, sig, info.si_code,
140                                 addr, current);
141 
142         force_sig_info (sig, &info, current);
143 }
144 
145 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
146 {
147         unsigned int insn;
148 
149         if (text_fault)
150                 return regs->pc;
151 
152         if (regs->psr & PSR_PS)
153                 insn = *(unsigned int *) regs->pc;
154         else
155                 __get_user(insn, (unsigned int *) regs->pc);
156 
157         return safe_compute_effective_address(regs, insn);
158 }
159 
160 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
161                                       int text_fault)
162 {
163         unsigned long addr = compute_si_addr(regs, text_fault);
164 
165         __do_fault_siginfo(code, sig, regs, addr);
166 }
167 
168 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
169                                unsigned long address)
170 {
171         struct vm_area_struct *vma;
172         struct task_struct *tsk = current;
173         struct mm_struct *mm = tsk->mm;
174         unsigned int fixup;
175         unsigned long g2;
176         int from_user = !(regs->psr & PSR_PS);
177         int fault, code;
178         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
179 
180         if (text_fault)
181                 address = regs->pc;
182 
183         /*
184          * We fault-in kernel-space virtual memory on-demand. The
185          * 'reference' page table is init_mm.pgd.
186          *
187          * NOTE! We MUST NOT take any locks for this case. We may
188          * be in an interrupt or a critical region, and should
189          * only copy the information from the master page table,
190          * nothing more.
191          */
192         code = SEGV_MAPERR;
193         if (address >= TASK_SIZE)
194                 goto vmalloc_fault;
195 
196         /*
197          * If we're in an interrupt or have no user
198          * context, we must not take the fault..
199          */
200         if (pagefault_disabled() || !mm)
201                 goto no_context;
202 
203         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
204 
205 retry:
206         down_read(&mm->mmap_sem);
207 
208         if (!from_user && address >= PAGE_OFFSET)
209                 goto bad_area;
210 
211         vma = find_vma(mm, address);
212         if (!vma)
213                 goto bad_area;
214         if (vma->vm_start <= address)
215                 goto good_area;
216         if (!(vma->vm_flags & VM_GROWSDOWN))
217                 goto bad_area;
218         if (expand_stack(vma, address))
219                 goto bad_area;
220         /*
221          * Ok, we have a good vm_area for this memory access, so
222          * we can handle it..
223          */
224 good_area:
225         code = SEGV_ACCERR;
226         if (write) {
227                 if (!(vma->vm_flags & VM_WRITE))
228                         goto bad_area;
229         } else {
230                 /* Allow reads even for write-only mappings */
231                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
232                         goto bad_area;
233         }
234 
235         if (from_user)
236                 flags |= FAULT_FLAG_USER;
237         if (write)
238                 flags |= FAULT_FLAG_WRITE;
239 
240         /*
241          * If for any reason at all we couldn't handle the fault,
242          * make sure we exit gracefully rather than endlessly redo
243          * the fault.
244          */
245         fault = handle_mm_fault(vma, address, flags);
246 
247         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
248                 return;
249 
250         if (unlikely(fault & VM_FAULT_ERROR)) {
251                 if (fault & VM_FAULT_OOM)
252                         goto out_of_memory;
253                 else if (fault & VM_FAULT_SIGSEGV)
254                         goto bad_area;
255                 else if (fault & VM_FAULT_SIGBUS)
256                         goto do_sigbus;
257                 BUG();
258         }
259 
260         if (flags & FAULT_FLAG_ALLOW_RETRY) {
261                 if (fault & VM_FAULT_MAJOR) {
262                         current->maj_flt++;
263                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
264                                       1, regs, address);
265                 } else {
266                         current->min_flt++;
267                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
268                                       1, regs, address);
269                 }
270                 if (fault & VM_FAULT_RETRY) {
271                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
272                         flags |= FAULT_FLAG_TRIED;
273 
274                         /* No need to up_read(&mm->mmap_sem) as we would
275                          * have already released it in __lock_page_or_retry
276                          * in mm/filemap.c.
277                          */
278 
279                         goto retry;
280                 }
281         }
282 
283         up_read(&mm->mmap_sem);
284         return;
285 
286         /*
287          * Something tried to access memory that isn't in our memory map..
288          * Fix it, but check if it's kernel or user first..
289          */
290 bad_area:
291         up_read(&mm->mmap_sem);
292 
293 bad_area_nosemaphore:
294         /* User mode accesses just cause a SIGSEGV */
295         if (from_user) {
296                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
297                 return;
298         }
299 
300         /* Is this in ex_table? */
301 no_context:
302         g2 = regs->u_regs[UREG_G2];
303         if (!from_user) {
304                 fixup = search_extables_range(regs->pc, &g2);
305                 /* Values below 10 are reserved for other things */
306                 if (fixup > 10) {
307                         extern const unsigned int __memset_start[];
308                         extern const unsigned int __memset_end[];
309                         extern const unsigned int __csum_partial_copy_start[];
310                         extern const unsigned int __csum_partial_copy_end[];
311 
312 #ifdef DEBUG_EXCEPTIONS
313                         printk("Exception: PC<%08lx> faddr<%08lx>\n",
314                                regs->pc, address);
315                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
316                                 regs->pc, fixup, g2);
317 #endif
318                         if ((regs->pc >= (unsigned long)__memset_start &&
319                              regs->pc < (unsigned long)__memset_end) ||
320                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
321                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
322                                 regs->u_regs[UREG_I4] = address;
323                                 regs->u_regs[UREG_I5] = regs->pc;
324                         }
325                         regs->u_regs[UREG_G2] = g2;
326                         regs->pc = fixup;
327                         regs->npc = regs->pc + 4;
328                         return;
329                 }
330         }
331 
332         unhandled_fault(address, tsk, regs);
333         do_exit(SIGKILL);
334 
335 /*
336  * We ran out of memory, or some other thing happened to us that made
337  * us unable to handle the page fault gracefully.
338  */
339 out_of_memory:
340         up_read(&mm->mmap_sem);
341         if (from_user) {
342                 pagefault_out_of_memory();
343                 return;
344         }
345         goto no_context;
346 
347 do_sigbus:
348         up_read(&mm->mmap_sem);
349         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
350         if (!from_user)
351                 goto no_context;
352 
353 vmalloc_fault:
354         {
355                 /*
356                  * Synchronize this task's top level page-table
357                  * with the 'reference' page table.
358                  */
359                 int offset = pgd_index(address);
360                 pgd_t *pgd, *pgd_k;
361                 pmd_t *pmd, *pmd_k;
362 
363                 pgd = tsk->active_mm->pgd + offset;
364                 pgd_k = init_mm.pgd + offset;
365 
366                 if (!pgd_present(*pgd)) {
367                         if (!pgd_present(*pgd_k))
368                                 goto bad_area_nosemaphore;
369                         pgd_val(*pgd) = pgd_val(*pgd_k);
370                         return;
371                 }
372 
373                 pmd = pmd_offset(pgd, address);
374                 pmd_k = pmd_offset(pgd_k, address);
375 
376                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
377                         goto bad_area_nosemaphore;
378 
379                 *pmd = *pmd_k;
380                 return;
381         }
382 }
383 
384 /* This always deals with user addresses. */
385 static void force_user_fault(unsigned long address, int write)
386 {
387         struct vm_area_struct *vma;
388         struct task_struct *tsk = current;
389         struct mm_struct *mm = tsk->mm;
390         unsigned int flags = FAULT_FLAG_USER;
391         int code;
392 
393         code = SEGV_MAPERR;
394 
395         down_read(&mm->mmap_sem);
396         vma = find_vma(mm, address);
397         if (!vma)
398                 goto bad_area;
399         if (vma->vm_start <= address)
400                 goto good_area;
401         if (!(vma->vm_flags & VM_GROWSDOWN))
402                 goto bad_area;
403         if (expand_stack(vma, address))
404                 goto bad_area;
405 good_area:
406         code = SEGV_ACCERR;
407         if (write) {
408                 if (!(vma->vm_flags & VM_WRITE))
409                         goto bad_area;
410                 flags |= FAULT_FLAG_WRITE;
411         } else {
412                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
413                         goto bad_area;
414         }
415         switch (handle_mm_fault(vma, address, flags)) {
416         case VM_FAULT_SIGBUS:
417         case VM_FAULT_OOM:
418                 goto do_sigbus;
419         }
420         up_read(&mm->mmap_sem);
421         return;
422 bad_area:
423         up_read(&mm->mmap_sem);
424         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
425         return;
426 
427 do_sigbus:
428         up_read(&mm->mmap_sem);
429         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
430 }
431 
432 static void check_stack_aligned(unsigned long sp)
433 {
434         if (sp & 0x7UL)
435                 force_sig(SIGILL, current);
436 }
437 
438 void window_overflow_fault(void)
439 {
440         unsigned long sp;
441 
442         sp = current_thread_info()->rwbuf_stkptrs[0];
443         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
444                 force_user_fault(sp + 0x38, 1);
445         force_user_fault(sp, 1);
446 
447         check_stack_aligned(sp);
448 }
449 
450 void window_underflow_fault(unsigned long sp)
451 {
452         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
453                 force_user_fault(sp + 0x38, 0);
454         force_user_fault(sp, 0);
455 
456         check_stack_aligned(sp);
457 }
458 
459 void window_ret_fault(struct pt_regs *regs)
460 {
461         unsigned long sp;
462 
463         sp = regs->u_regs[UREG_FP];
464         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
465                 force_user_fault(sp + 0x38, 0);
466         force_user_fault(sp, 0);
467 
468         check_stack_aligned(sp);
469 }
470 

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