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Linux/arch/parisc/mm/fault.c

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  1 /*
  2  * This file is subject to the terms and conditions of the GNU General Public
  3  * License.  See the file "COPYING" in the main directory of this archive
  4  * for more details.
  5  *
  6  *
  7  * Copyright (C) 1995, 1996, 1997, 1998 by Ralf Baechle
  8  * Copyright 1999 SuSE GmbH (Philipp Rumpf, prumpf@tux.org)
  9  * Copyright 1999 Hewlett Packard Co.
 10  *
 11  */
 12 
 13 #include <linux/mm.h>
 14 #include <linux/ptrace.h>
 15 #include <linux/sched.h>
 16 #include <linux/sched/debug.h>
 17 #include <linux/interrupt.h>
 18 #include <linux/extable.h>
 19 #include <linux/uaccess.h>
 20 #include <linux/hugetlb.h>
 21 
 22 #include <asm/traps.h>
 23 
 24 /* Various important other fields */
 25 #define bit22set(x)             (x & 0x00000200)
 26 #define bits23_25set(x)         (x & 0x000001c0)
 27 #define isGraphicsFlushRead(x)  ((x & 0xfc003fdf) == 0x04001a80)
 28                                 /* extended opcode is 0x6a */
 29 
 30 #define BITSSET         0x1c0   /* for identifying LDCW */
 31 
 32 
 33 int show_unhandled_signals = 1;
 34 
 35 /*
 36  * parisc_acctyp(unsigned int inst) --
 37  *    Given a PA-RISC memory access instruction, determine if the
 38  *    the instruction would perform a memory read or memory write
 39  *    operation.
 40  *
 41  *    This function assumes that the given instruction is a memory access
 42  *    instruction (i.e. you should really only call it if you know that
 43  *    the instruction has generated some sort of a memory access fault).
 44  *
 45  * Returns:
 46  *   VM_READ  if read operation
 47  *   VM_WRITE if write operation
 48  *   VM_EXEC  if execute operation
 49  */
 50 static unsigned long
 51 parisc_acctyp(unsigned long code, unsigned int inst)
 52 {
 53         if (code == 6 || code == 16)
 54             return VM_EXEC;
 55 
 56         switch (inst & 0xf0000000) {
 57         case 0x40000000: /* load */
 58         case 0x50000000: /* new load */
 59                 return VM_READ;
 60 
 61         case 0x60000000: /* store */
 62         case 0x70000000: /* new store */
 63                 return VM_WRITE;
 64 
 65         case 0x20000000: /* coproc */
 66         case 0x30000000: /* coproc2 */
 67                 if (bit22set(inst))
 68                         return VM_WRITE;
 69                 /* fall through */
 70 
 71         case 0x0: /* indexed/memory management */
 72                 if (bit22set(inst)) {
 73                         /*
 74                          * Check for the 'Graphics Flush Read' instruction.
 75                          * It resembles an FDC instruction, except for bits
 76                          * 20 and 21. Any combination other than zero will
 77                          * utilize the block mover functionality on some
 78                          * older PA-RISC platforms.  The case where a block
 79                          * move is performed from VM to graphics IO space
 80                          * should be treated as a READ.
 81                          *
 82                          * The significance of bits 20,21 in the FDC
 83                          * instruction is:
 84                          *
 85                          *   00  Flush data cache (normal instruction behavior)
 86                          *   01  Graphics flush write  (IO space -> VM)
 87                          *   10  Graphics flush read   (VM -> IO space)
 88                          *   11  Graphics flush read/write (VM <-> IO space)
 89                          */
 90                         if (isGraphicsFlushRead(inst))
 91                                 return VM_READ;
 92                         return VM_WRITE;
 93                 } else {
 94                         /*
 95                          * Check for LDCWX and LDCWS (semaphore instructions).
 96                          * If bits 23 through 25 are all 1's it is one of
 97                          * the above two instructions and is a write.
 98                          *
 99                          * Note: With the limited bits we are looking at,
100                          * this will also catch PROBEW and PROBEWI. However,
101                          * these should never get in here because they don't
102                          * generate exceptions of the type:
103                          *   Data TLB miss fault/data page fault
104                          *   Data memory protection trap
105                          */
106                         if (bits23_25set(inst) == BITSSET)
107                                 return VM_WRITE;
108                 }
109                 return VM_READ; /* Default */
110         }
111         return VM_READ; /* Default */
112 }
113 
114 #undef bit22set
115 #undef bits23_25set
116 #undef isGraphicsFlushRead
117 #undef BITSSET
118 
119 
120 #if 0
121 /* This is the treewalk to find a vma which is the highest that has
122  * a start < addr.  We're using find_vma_prev instead right now, but
123  * we might want to use this at some point in the future.  Probably
124  * not, but I want it committed to CVS so I don't lose it :-)
125  */
126                         while (tree != vm_avl_empty) {
127                                 if (tree->vm_start > addr) {
128                                         tree = tree->vm_avl_left;
129                                 } else {
130                                         prev = tree;
131                                         if (prev->vm_next == NULL)
132                                                 break;
133                                         if (prev->vm_next->vm_start > addr)
134                                                 break;
135                                         tree = tree->vm_avl_right;
136                                 }
137                         }
138 #endif
139 
140 int fixup_exception(struct pt_regs *regs)
141 {
142         const struct exception_table_entry *fix;
143 
144         fix = search_exception_tables(regs->iaoq[0]);
145         if (fix) {
146                 /*
147                  * Fix up get_user() and put_user().
148                  * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() sets the least-significant
149                  * bit in the relative address of the fixup routine to indicate
150                  * that %r8 should be loaded with -EFAULT to report a userspace
151                  * access error.
152                  */
153                 if (fix->fixup & 1) {
154                         regs->gr[8] = -EFAULT;
155 
156                         /* zero target register for get_user() */
157                         if (parisc_acctyp(0, regs->iir) == VM_READ) {
158                                 int treg = regs->iir & 0x1f;
159                                 BUG_ON(treg == 0);
160                                 regs->gr[treg] = 0;
161                         }
162                 }
163 
164                 regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup;
165                 regs->iaoq[0] &= ~3;
166                 /*
167                  * NOTE: In some cases the faulting instruction
168                  * may be in the delay slot of a branch. We
169                  * don't want to take the branch, so we don't
170                  * increment iaoq[1], instead we set it to be
171                  * iaoq[0]+4, and clear the B bit in the PSW
172                  */
173                 regs->iaoq[1] = regs->iaoq[0] + 4;
174                 regs->gr[0] &= ~PSW_B; /* IPSW in gr[0] */
175 
176                 return 1;
177         }
178 
179         return 0;
180 }
181 
182 /*
183  * parisc hardware trap list
184  *
185  * Documented in section 3 "Addressing and Access Control" of the
186  * "PA-RISC 1.1 Architecture and Instruction Set Reference Manual"
187  * https://parisc.wiki.kernel.org/index.php/File:Pa11_acd.pdf
188  *
189  * For implementation see handle_interruption() in traps.c
190  */
191 static const char * const trap_description[] = {
192         [1] "High-priority machine check (HPMC)",
193         [2] "Power failure interrupt",
194         [3] "Recovery counter trap",
195         [5] "Low-priority machine check",
196         [6] "Instruction TLB miss fault",
197         [7] "Instruction access rights / protection trap",
198         [8] "Illegal instruction trap",
199         [9] "Break instruction trap",
200         [10] "Privileged operation trap",
201         [11] "Privileged register trap",
202         [12] "Overflow trap",
203         [13] "Conditional trap",
204         [14] "FP Assist Exception trap",
205         [15] "Data TLB miss fault",
206         [16] "Non-access ITLB miss fault",
207         [17] "Non-access DTLB miss fault",
208         [18] "Data memory protection/unaligned access trap",
209         [19] "Data memory break trap",
210         [20] "TLB dirty bit trap",
211         [21] "Page reference trap",
212         [22] "Assist emulation trap",
213         [25] "Taken branch trap",
214         [26] "Data memory access rights trap",
215         [27] "Data memory protection ID trap",
216         [28] "Unaligned data reference trap",
217 };
218 
219 const char *trap_name(unsigned long code)
220 {
221         const char *t = NULL;
222 
223         if (code < ARRAY_SIZE(trap_description))
224                 t = trap_description[code];
225 
226         return t ? t : "Unknown trap";
227 }
228 
229 /*
230  * Print out info about fatal segfaults, if the show_unhandled_signals
231  * sysctl is set:
232  */
233 static inline void
234 show_signal_msg(struct pt_regs *regs, unsigned long code,
235                 unsigned long address, struct task_struct *tsk,
236                 struct vm_area_struct *vma)
237 {
238         if (!unhandled_signal(tsk, SIGSEGV))
239                 return;
240 
241         if (!printk_ratelimit())
242                 return;
243 
244         pr_warn("\n");
245         pr_warn("do_page_fault() command='%s' type=%lu address=0x%08lx",
246             tsk->comm, code, address);
247         print_vma_addr(KERN_CONT " in ", regs->iaoq[0]);
248 
249         pr_cont("\ntrap #%lu: %s%c", code, trap_name(code),
250                 vma ? ',':'\n');
251 
252         if (vma)
253                 pr_cont(" vm_start = 0x%08lx, vm_end = 0x%08lx\n",
254                         vma->vm_start, vma->vm_end);
255 
256         show_regs(regs);
257 }
258 
259 void do_page_fault(struct pt_regs *regs, unsigned long code,
260                               unsigned long address)
261 {
262         struct vm_area_struct *vma, *prev_vma;
263         struct task_struct *tsk;
264         struct mm_struct *mm;
265         unsigned long acc_type;
266         vm_fault_t fault = 0;
267         unsigned int flags;
268 
269         if (faulthandler_disabled())
270                 goto no_context;
271 
272         tsk = current;
273         mm = tsk->mm;
274         if (!mm)
275                 goto no_context;
276 
277         flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
278         if (user_mode(regs))
279                 flags |= FAULT_FLAG_USER;
280 
281         acc_type = parisc_acctyp(code, regs->iir);
282         if (acc_type & VM_WRITE)
283                 flags |= FAULT_FLAG_WRITE;
284 retry:
285         down_read(&mm->mmap_sem);
286         vma = find_vma_prev(mm, address, &prev_vma);
287         if (!vma || address < vma->vm_start)
288                 goto check_expansion;
289 /*
290  * Ok, we have a good vm_area for this memory access. We still need to
291  * check the access permissions.
292  */
293 
294 good_area:
295 
296         if ((vma->vm_flags & acc_type) != acc_type)
297                 goto bad_area;
298 
299         /*
300          * If for any reason at all we couldn't handle the fault, make
301          * sure we exit gracefully rather than endlessly redo the
302          * fault.
303          */
304 
305         fault = handle_mm_fault(vma, address, flags);
306 
307         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
308                 return;
309 
310         if (unlikely(fault & VM_FAULT_ERROR)) {
311                 /*
312                  * We hit a shared mapping outside of the file, or some
313                  * other thing happened to us that made us unable to
314                  * handle the page fault gracefully.
315                  */
316                 if (fault & VM_FAULT_OOM)
317                         goto out_of_memory;
318                 else if (fault & VM_FAULT_SIGSEGV)
319                         goto bad_area;
320                 else if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
321                                   VM_FAULT_HWPOISON_LARGE))
322                         goto bad_area;
323                 BUG();
324         }
325         if (flags & FAULT_FLAG_ALLOW_RETRY) {
326                 if (fault & VM_FAULT_MAJOR)
327                         current->maj_flt++;
328                 else
329                         current->min_flt++;
330                 if (fault & VM_FAULT_RETRY) {
331                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
332 
333                         /*
334                          * No need to up_read(&mm->mmap_sem) as we would
335                          * have already released it in __lock_page_or_retry
336                          * in mm/filemap.c.
337                          */
338 
339                         goto retry;
340                 }
341         }
342         up_read(&mm->mmap_sem);
343         return;
344 
345 check_expansion:
346         vma = prev_vma;
347         if (vma && (expand_stack(vma, address) == 0))
348                 goto good_area;
349 
350 /*
351  * Something tried to access memory that isn't in our memory map..
352  */
353 bad_area:
354         up_read(&mm->mmap_sem);
355 
356         if (user_mode(regs)) {
357                 int signo, si_code;
358 
359                 switch (code) {
360                 case 15:        /* Data TLB miss fault/Data page fault */
361                         /* send SIGSEGV when outside of vma */
362                         if (!vma ||
363                             address < vma->vm_start || address >= vma->vm_end) {
364                                 signo = SIGSEGV;
365                                 si_code = SEGV_MAPERR;
366                                 break;
367                         }
368 
369                         /* send SIGSEGV for wrong permissions */
370                         if ((vma->vm_flags & acc_type) != acc_type) {
371                                 signo = SIGSEGV;
372                                 si_code = SEGV_ACCERR;
373                                 break;
374                         }
375 
376                         /* probably address is outside of mapped file */
377                         /* fall through */
378                 case 17:        /* NA data TLB miss / page fault */
379                 case 18:        /* Unaligned access - PCXS only */
380                         signo = SIGBUS;
381                         si_code = (code == 18) ? BUS_ADRALN : BUS_ADRERR;
382                         break;
383                 case 16:        /* Non-access instruction TLB miss fault */
384                 case 26:        /* PCXL: Data memory access rights trap */
385                 default:
386                         signo = SIGSEGV;
387                         si_code = (code == 26) ? SEGV_ACCERR : SEGV_MAPERR;
388                         break;
389                 }
390 #ifdef CONFIG_MEMORY_FAILURE
391                 if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
392                         unsigned int lsb = 0;
393                         printk(KERN_ERR
394         "MCE: Killing %s:%d due to hardware memory corruption fault at %08lx\n",
395                         tsk->comm, tsk->pid, address);
396                         /*
397                          * Either small page or large page may be poisoned.
398                          * In other words, VM_FAULT_HWPOISON_LARGE and
399                          * VM_FAULT_HWPOISON are mutually exclusive.
400                          */
401                         if (fault & VM_FAULT_HWPOISON_LARGE)
402                                 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
403                         else if (fault & VM_FAULT_HWPOISON)
404                                 lsb = PAGE_SHIFT;
405 
406                         force_sig_mceerr(BUS_MCEERR_AR, (void __user *) address,
407                                          lsb);
408                         return;
409                 }
410 #endif
411                 show_signal_msg(regs, code, address, tsk, vma);
412 
413                 force_sig_fault(signo, si_code, (void __user *) address);
414                 return;
415         }
416 
417 no_context:
418 
419         if (!user_mode(regs) && fixup_exception(regs)) {
420                 return;
421         }
422 
423         parisc_terminate("Bad Address (null pointer deref?)", regs, code, address);
424 
425   out_of_memory:
426         up_read(&mm->mmap_sem);
427         if (!user_mode(regs))
428                 goto no_context;
429         pagefault_out_of_memory();
430 }
431 

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