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/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
unhandled_fault(unsigned long address,struct task_struct * tsk,struct pt_regs * regs)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
lookup_fault(unsigned long pc,unsigned long ret_pc,unsigned long address)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(®s, 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, ®s);
100
101 /* Not reached */
102 return 0;
103 }
104
105 static inline void
show_signal_msg(struct pt_regs * regs,int sig,int code,unsigned long address,struct task_struct * tsk)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 %px (rpc %px) sp %px 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
__do_fault_siginfo(int code,int sig,struct pt_regs * regs,unsigned long addr)126 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
127 unsigned long addr)
128 {
129 if (unlikely(show_unhandled_signals))
130 show_signal_msg(regs, sig, code,
131 addr, current);
132
133 force_sig_fault(sig, code, (void __user *) addr, 0);
134 }
135
compute_si_addr(struct pt_regs * regs,int text_fault)136 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
137 {
138 unsigned int insn;
139
140 if (text_fault)
141 return regs->pc;
142
143 if (regs->psr & PSR_PS)
144 insn = *(unsigned int *) regs->pc;
145 else
146 __get_user(insn, (unsigned int *) regs->pc);
147
148 return safe_compute_effective_address(regs, insn);
149 }
150
do_fault_siginfo(int code,int sig,struct pt_regs * regs,int text_fault)151 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
152 int text_fault)
153 {
154 unsigned long addr = compute_si_addr(regs, text_fault);
155
156 __do_fault_siginfo(code, sig, regs, addr);
157 }
158
do_sparc_fault(struct pt_regs * regs,int text_fault,int write,unsigned long address)159 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
160 unsigned long address)
161 {
162 struct vm_area_struct *vma;
163 struct task_struct *tsk = current;
164 struct mm_struct *mm = tsk->mm;
165 unsigned int fixup;
166 unsigned long g2;
167 int from_user = !(regs->psr & PSR_PS);
168 int code;
169 vm_fault_t fault;
170 unsigned int flags = FAULT_FLAG_DEFAULT;
171
172 if (text_fault)
173 address = regs->pc;
174
175 /*
176 * We fault-in kernel-space virtual memory on-demand. The
177 * 'reference' page table is init_mm.pgd.
178 *
179 * NOTE! We MUST NOT take any locks for this case. We may
180 * be in an interrupt or a critical region, and should
181 * only copy the information from the master page table,
182 * nothing more.
183 */
184 code = SEGV_MAPERR;
185 if (address >= TASK_SIZE)
186 goto vmalloc_fault;
187
188 /*
189 * If we're in an interrupt or have no user
190 * context, we must not take the fault..
191 */
192 if (pagefault_disabled() || !mm)
193 goto no_context;
194
195 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
196
197 retry:
198 mmap_read_lock(mm);
199
200 if (!from_user && address >= PAGE_OFFSET)
201 goto bad_area;
202
203 vma = find_vma(mm, address);
204 if (!vma)
205 goto bad_area;
206 if (vma->vm_start <= address)
207 goto good_area;
208 if (!(vma->vm_flags & VM_GROWSDOWN))
209 goto bad_area;
210 if (expand_stack(vma, address))
211 goto bad_area;
212 /*
213 * Ok, we have a good vm_area for this memory access, so
214 * we can handle it..
215 */
216 good_area:
217 code = SEGV_ACCERR;
218 if (write) {
219 if (!(vma->vm_flags & VM_WRITE))
220 goto bad_area;
221 } else {
222 /* Allow reads even for write-only mappings */
223 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
224 goto bad_area;
225 }
226
227 if (from_user)
228 flags |= FAULT_FLAG_USER;
229 if (write)
230 flags |= FAULT_FLAG_WRITE;
231
232 /*
233 * If for any reason at all we couldn't handle the fault,
234 * make sure we exit gracefully rather than endlessly redo
235 * the fault.
236 */
237 fault = handle_mm_fault(vma, address, flags, regs);
238
239 if (fault_signal_pending(fault, regs))
240 return;
241
242 if (unlikely(fault & VM_FAULT_ERROR)) {
243 if (fault & VM_FAULT_OOM)
244 goto out_of_memory;
245 else if (fault & VM_FAULT_SIGSEGV)
246 goto bad_area;
247 else if (fault & VM_FAULT_SIGBUS)
248 goto do_sigbus;
249 BUG();
250 }
251
252 if (flags & FAULT_FLAG_ALLOW_RETRY) {
253 if (fault & VM_FAULT_RETRY) {
254 flags |= FAULT_FLAG_TRIED;
255
256 /* No need to mmap_read_unlock(mm) as we would
257 * have already released it in __lock_page_or_retry
258 * in mm/filemap.c.
259 */
260
261 goto retry;
262 }
263 }
264
265 mmap_read_unlock(mm);
266 return;
267
268 /*
269 * Something tried to access memory that isn't in our memory map..
270 * Fix it, but check if it's kernel or user first..
271 */
272 bad_area:
273 mmap_read_unlock(mm);
274
275 bad_area_nosemaphore:
276 /* User mode accesses just cause a SIGSEGV */
277 if (from_user) {
278 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
279 return;
280 }
281
282 /* Is this in ex_table? */
283 no_context:
284 g2 = regs->u_regs[UREG_G2];
285 if (!from_user) {
286 fixup = search_extables_range(regs->pc, &g2);
287 /* Values below 10 are reserved for other things */
288 if (fixup > 10) {
289 extern const unsigned int __memset_start[];
290 extern const unsigned int __memset_end[];
291
292 #ifdef DEBUG_EXCEPTIONS
293 printk("Exception: PC<%08lx> faddr<%08lx>\n",
294 regs->pc, address);
295 printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
296 regs->pc, fixup, g2);
297 #endif
298 if ((regs->pc >= (unsigned long)__memset_start &&
299 regs->pc < (unsigned long)__memset_end)) {
300 regs->u_regs[UREG_I4] = address;
301 regs->u_regs[UREG_I5] = regs->pc;
302 }
303 regs->u_regs[UREG_G2] = g2;
304 regs->pc = fixup;
305 regs->npc = regs->pc + 4;
306 return;
307 }
308 }
309
310 unhandled_fault(address, tsk, regs);
311 do_exit(SIGKILL);
312
313 /*
314 * We ran out of memory, or some other thing happened to us that made
315 * us unable to handle the page fault gracefully.
316 */
317 out_of_memory:
318 mmap_read_unlock(mm);
319 if (from_user) {
320 pagefault_out_of_memory();
321 return;
322 }
323 goto no_context;
324
325 do_sigbus:
326 mmap_read_unlock(mm);
327 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
328 if (!from_user)
329 goto no_context;
330
331 vmalloc_fault:
332 {
333 /*
334 * Synchronize this task's top level page-table
335 * with the 'reference' page table.
336 */
337 int offset = pgd_index(address);
338 pgd_t *pgd, *pgd_k;
339 p4d_t *p4d, *p4d_k;
340 pud_t *pud, *pud_k;
341 pmd_t *pmd, *pmd_k;
342
343 pgd = tsk->active_mm->pgd + offset;
344 pgd_k = init_mm.pgd + offset;
345
346 if (!pgd_present(*pgd)) {
347 if (!pgd_present(*pgd_k))
348 goto bad_area_nosemaphore;
349 pgd_val(*pgd) = pgd_val(*pgd_k);
350 return;
351 }
352
353 p4d = p4d_offset(pgd, address);
354 pud = pud_offset(p4d, address);
355 pmd = pmd_offset(pud, address);
356
357 p4d_k = p4d_offset(pgd_k, address);
358 pud_k = pud_offset(p4d_k, address);
359 pmd_k = pmd_offset(pud_k, address);
360
361 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
362 goto bad_area_nosemaphore;
363
364 *pmd = *pmd_k;
365 return;
366 }
367 }
368
369 /* This always deals with user addresses. */
force_user_fault(unsigned long address,int write)370 static void force_user_fault(unsigned long address, int write)
371 {
372 struct vm_area_struct *vma;
373 struct task_struct *tsk = current;
374 struct mm_struct *mm = tsk->mm;
375 unsigned int flags = FAULT_FLAG_USER;
376 int code;
377
378 code = SEGV_MAPERR;
379
380 mmap_read_lock(mm);
381 vma = find_vma(mm, address);
382 if (!vma)
383 goto bad_area;
384 if (vma->vm_start <= address)
385 goto good_area;
386 if (!(vma->vm_flags & VM_GROWSDOWN))
387 goto bad_area;
388 if (expand_stack(vma, address))
389 goto bad_area;
390 good_area:
391 code = SEGV_ACCERR;
392 if (write) {
393 if (!(vma->vm_flags & VM_WRITE))
394 goto bad_area;
395 flags |= FAULT_FLAG_WRITE;
396 } else {
397 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
398 goto bad_area;
399 }
400 switch (handle_mm_fault(vma, address, flags, NULL)) {
401 case VM_FAULT_SIGBUS:
402 case VM_FAULT_OOM:
403 goto do_sigbus;
404 }
405 mmap_read_unlock(mm);
406 return;
407 bad_area:
408 mmap_read_unlock(mm);
409 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
410 return;
411
412 do_sigbus:
413 mmap_read_unlock(mm);
414 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
415 }
416
check_stack_aligned(unsigned long sp)417 static void check_stack_aligned(unsigned long sp)
418 {
419 if (sp & 0x7UL)
420 force_sig(SIGILL);
421 }
422
window_overflow_fault(void)423 void window_overflow_fault(void)
424 {
425 unsigned long sp;
426
427 sp = current_thread_info()->rwbuf_stkptrs[0];
428 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
429 force_user_fault(sp + 0x38, 1);
430 force_user_fault(sp, 1);
431
432 check_stack_aligned(sp);
433 }
434
window_underflow_fault(unsigned long sp)435 void window_underflow_fault(unsigned long sp)
436 {
437 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
438 force_user_fault(sp + 0x38, 0);
439 force_user_fault(sp, 0);
440
441 check_stack_aligned(sp);
442 }
443
window_ret_fault(struct pt_regs * regs)444 void window_ret_fault(struct pt_regs *regs)
445 {
446 unsigned long sp;
447
448 sp = regs->u_regs[UREG_FP];
449 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
450 force_user_fault(sp + 0x38, 0);
451 force_user_fault(sp, 0);
452
453 check_stack_aligned(sp);
454 }
455
