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
unhandled_fault(unsigned long address,struct task_struct * tsk,struct pt_regs * regs)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
lookup_fault(unsigned long pc,unsigned long ret_pc,unsigned long address)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(®s, 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, ®s);
101
102 /* Not reached */
103 return 0;
104 }
105
106 static inline void
show_signal_msg(struct pt_regs * regs,int sig,int code,unsigned long address,struct task_struct * tsk)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
__do_fault_siginfo(int code,int sig,struct pt_regs * regs,unsigned long addr)127 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
128 unsigned long addr)
129 {
130 if (unlikely(show_unhandled_signals))
131 show_signal_msg(regs, sig, code,
132 addr, current);
133
134 force_sig_fault(sig, code, (void __user *) addr, 0);
135 }
136
compute_si_addr(struct pt_regs * regs,int text_fault)137 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
138 {
139 unsigned int insn;
140
141 if (text_fault)
142 return regs->pc;
143
144 if (regs->psr & PSR_PS)
145 insn = *(unsigned int *) regs->pc;
146 else
147 __get_user(insn, (unsigned int *) regs->pc);
148
149 return safe_compute_effective_address(regs, insn);
150 }
151
do_fault_siginfo(int code,int sig,struct pt_regs * regs,int text_fault)152 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
153 int text_fault)
154 {
155 unsigned long addr = compute_si_addr(regs, text_fault);
156
157 __do_fault_siginfo(code, sig, regs, addr);
158 }
159
do_sparc_fault(struct pt_regs * regs,int text_fault,int write,unsigned long address)160 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
161 unsigned long address)
162 {
163 struct vm_area_struct *vma;
164 struct task_struct *tsk = current;
165 struct mm_struct *mm = tsk->mm;
166 unsigned int fixup;
167 unsigned long g2;
168 int from_user = !(regs->psr & PSR_PS);
169 int code;
170 vm_fault_t fault;
171 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
172
173 if (text_fault)
174 address = regs->pc;
175
176 /*
177 * We fault-in kernel-space virtual memory on-demand. The
178 * 'reference' page table is init_mm.pgd.
179 *
180 * NOTE! We MUST NOT take any locks for this case. We may
181 * be in an interrupt or a critical region, and should
182 * only copy the information from the master page table,
183 * nothing more.
184 */
185 code = SEGV_MAPERR;
186 if (address >= TASK_SIZE)
187 goto vmalloc_fault;
188
189 /*
190 * If we're in an interrupt or have no user
191 * context, we must not take the fault..
192 */
193 if (pagefault_disabled() || !mm)
194 goto no_context;
195
196 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
197
198 retry:
199 down_read(&mm->mmap_sem);
200
201 if (!from_user && address >= PAGE_OFFSET)
202 goto bad_area;
203
204 vma = find_vma(mm, address);
205 if (!vma)
206 goto bad_area;
207 if (vma->vm_start <= address)
208 goto good_area;
209 if (!(vma->vm_flags & VM_GROWSDOWN))
210 goto bad_area;
211 if (expand_stack(vma, address))
212 goto bad_area;
213 /*
214 * Ok, we have a good vm_area for this memory access, so
215 * we can handle it..
216 */
217 good_area:
218 code = SEGV_ACCERR;
219 if (write) {
220 if (!(vma->vm_flags & VM_WRITE))
221 goto bad_area;
222 } else {
223 /* Allow reads even for write-only mappings */
224 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
225 goto bad_area;
226 }
227
228 if (from_user)
229 flags |= FAULT_FLAG_USER;
230 if (write)
231 flags |= FAULT_FLAG_WRITE;
232
233 /*
234 * If for any reason at all we couldn't handle the fault,
235 * make sure we exit gracefully rather than endlessly redo
236 * the fault.
237 */
238 fault = handle_mm_fault(vma, address, flags);
239
240 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
241 return;
242
243 if (unlikely(fault & VM_FAULT_ERROR)) {
244 if (fault & VM_FAULT_OOM)
245 goto out_of_memory;
246 else if (fault & VM_FAULT_SIGSEGV)
247 goto bad_area;
248 else if (fault & VM_FAULT_SIGBUS)
249 goto do_sigbus;
250 BUG();
251 }
252
253 if (flags & FAULT_FLAG_ALLOW_RETRY) {
254 if (fault & VM_FAULT_MAJOR) {
255 current->maj_flt++;
256 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
257 1, regs, address);
258 } else {
259 current->min_flt++;
260 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
261 1, regs, address);
262 }
263 if (fault & VM_FAULT_RETRY) {
264 flags &= ~FAULT_FLAG_ALLOW_RETRY;
265 flags |= FAULT_FLAG_TRIED;
266
267 /* No need to up_read(&mm->mmap_sem) as we would
268 * have already released it in __lock_page_or_retry
269 * in mm/filemap.c.
270 */
271
272 goto retry;
273 }
274 }
275
276 up_read(&mm->mmap_sem);
277 return;
278
279 /*
280 * Something tried to access memory that isn't in our memory map..
281 * Fix it, but check if it's kernel or user first..
282 */
283 bad_area:
284 up_read(&mm->mmap_sem);
285
286 bad_area_nosemaphore:
287 /* User mode accesses just cause a SIGSEGV */
288 if (from_user) {
289 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
290 return;
291 }
292
293 /* Is this in ex_table? */
294 no_context:
295 g2 = regs->u_regs[UREG_G2];
296 if (!from_user) {
297 fixup = search_extables_range(regs->pc, &g2);
298 /* Values below 10 are reserved for other things */
299 if (fixup > 10) {
300 extern const unsigned int __memset_start[];
301 extern const unsigned int __memset_end[];
302 extern const unsigned int __csum_partial_copy_start[];
303 extern const unsigned int __csum_partial_copy_end[];
304
305 #ifdef DEBUG_EXCEPTIONS
306 printk("Exception: PC<%08lx> faddr<%08lx>\n",
307 regs->pc, address);
308 printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
309 regs->pc, fixup, g2);
310 #endif
311 if ((regs->pc >= (unsigned long)__memset_start &&
312 regs->pc < (unsigned long)__memset_end) ||
313 (regs->pc >= (unsigned long)__csum_partial_copy_start &&
314 regs->pc < (unsigned long)__csum_partial_copy_end)) {
315 regs->u_regs[UREG_I4] = address;
316 regs->u_regs[UREG_I5] = regs->pc;
317 }
318 regs->u_regs[UREG_G2] = g2;
319 regs->pc = fixup;
320 regs->npc = regs->pc + 4;
321 return;
322 }
323 }
324
325 unhandled_fault(address, tsk, regs);
326 do_exit(SIGKILL);
327
328 /*
329 * We ran out of memory, or some other thing happened to us that made
330 * us unable to handle the page fault gracefully.
331 */
332 out_of_memory:
333 up_read(&mm->mmap_sem);
334 if (from_user) {
335 pagefault_out_of_memory();
336 return;
337 }
338 goto no_context;
339
340 do_sigbus:
341 up_read(&mm->mmap_sem);
342 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
343 if (!from_user)
344 goto no_context;
345
346 vmalloc_fault:
347 {
348 /*
349 * Synchronize this task's top level page-table
350 * with the 'reference' page table.
351 */
352 int offset = pgd_index(address);
353 pgd_t *pgd, *pgd_k;
354 pmd_t *pmd, *pmd_k;
355
356 pgd = tsk->active_mm->pgd + offset;
357 pgd_k = init_mm.pgd + offset;
358
359 if (!pgd_present(*pgd)) {
360 if (!pgd_present(*pgd_k))
361 goto bad_area_nosemaphore;
362 pgd_val(*pgd) = pgd_val(*pgd_k);
363 return;
364 }
365
366 pmd = pmd_offset(pgd, address);
367 pmd_k = pmd_offset(pgd_k, address);
368
369 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
370 goto bad_area_nosemaphore;
371
372 *pmd = *pmd_k;
373 return;
374 }
375 }
376
377 /* This always deals with user addresses. */
force_user_fault(unsigned long address,int write)378 static void force_user_fault(unsigned long address, int write)
379 {
380 struct vm_area_struct *vma;
381 struct task_struct *tsk = current;
382 struct mm_struct *mm = tsk->mm;
383 unsigned int flags = FAULT_FLAG_USER;
384 int code;
385
386 code = SEGV_MAPERR;
387
388 down_read(&mm->mmap_sem);
389 vma = find_vma(mm, address);
390 if (!vma)
391 goto bad_area;
392 if (vma->vm_start <= address)
393 goto good_area;
394 if (!(vma->vm_flags & VM_GROWSDOWN))
395 goto bad_area;
396 if (expand_stack(vma, address))
397 goto bad_area;
398 good_area:
399 code = SEGV_ACCERR;
400 if (write) {
401 if (!(vma->vm_flags & VM_WRITE))
402 goto bad_area;
403 flags |= FAULT_FLAG_WRITE;
404 } else {
405 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
406 goto bad_area;
407 }
408 switch (handle_mm_fault(vma, address, flags)) {
409 case VM_FAULT_SIGBUS:
410 case VM_FAULT_OOM:
411 goto do_sigbus;
412 }
413 up_read(&mm->mmap_sem);
414 return;
415 bad_area:
416 up_read(&mm->mmap_sem);
417 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
418 return;
419
420 do_sigbus:
421 up_read(&mm->mmap_sem);
422 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
423 }
424
check_stack_aligned(unsigned long sp)425 static void check_stack_aligned(unsigned long sp)
426 {
427 if (sp & 0x7UL)
428 force_sig(SIGILL);
429 }
430
window_overflow_fault(void)431 void window_overflow_fault(void)
432 {
433 unsigned long sp;
434
435 sp = current_thread_info()->rwbuf_stkptrs[0];
436 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
437 force_user_fault(sp + 0x38, 1);
438 force_user_fault(sp, 1);
439
440 check_stack_aligned(sp);
441 }
442
window_underflow_fault(unsigned long sp)443 void window_underflow_fault(unsigned long sp)
444 {
445 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
446 force_user_fault(sp + 0x38, 0);
447 force_user_fault(sp, 0);
448
449 check_stack_aligned(sp);
450 }
451
window_ret_fault(struct pt_regs * regs)452 void window_ret_fault(struct pt_regs *regs)
453 {
454 unsigned long sp;
455
456 sp = regs->u_regs[UREG_FP];
457 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
458 force_user_fault(sp + 0x38, 0);
459 force_user_fault(sp, 0);
460
461 check_stack_aligned(sp);
462 }
463
