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 #include <linux/extable.h>
27
28 #include <asm/page.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
58 static inline void
show_signal_msg(struct pt_regs * regs,int sig,int code,unsigned long address,struct task_struct * tsk)59 show_signal_msg(struct pt_regs *regs, int sig, int code,
60 unsigned long address, struct task_struct *tsk)
61 {
62 if (!unhandled_signal(tsk, sig))
63 return;
64
65 if (!printk_ratelimit())
66 return;
67
68 printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
69 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
70 tsk->comm, task_pid_nr(tsk), address,
71 (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
72 (void *)regs->u_regs[UREG_FP], code);
73
74 print_vma_addr(KERN_CONT " in ", regs->pc);
75
76 printk(KERN_CONT "\n");
77 }
78
__do_fault_siginfo(int code,int sig,struct pt_regs * regs,unsigned long addr)79 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
80 unsigned long addr)
81 {
82 if (unlikely(show_unhandled_signals))
83 show_signal_msg(regs, sig, code,
84 addr, current);
85
86 force_sig_fault(sig, code, (void __user *) addr);
87 }
88
compute_si_addr(struct pt_regs * regs,int text_fault)89 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
90 {
91 unsigned int insn;
92
93 if (text_fault)
94 return regs->pc;
95
96 if (regs->psr & PSR_PS)
97 insn = *(unsigned int *) regs->pc;
98 else
99 __get_user(insn, (unsigned int *) regs->pc);
100
101 return safe_compute_effective_address(regs, insn);
102 }
103
do_fault_siginfo(int code,int sig,struct pt_regs * regs,int text_fault)104 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
105 int text_fault)
106 {
107 unsigned long addr = compute_si_addr(regs, text_fault);
108
109 __do_fault_siginfo(code, sig, regs, addr);
110 }
111
do_sparc_fault(struct pt_regs * regs,int text_fault,int write,unsigned long address)112 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
113 unsigned long address)
114 {
115 struct vm_area_struct *vma;
116 struct task_struct *tsk = current;
117 struct mm_struct *mm = tsk->mm;
118 int from_user = !(regs->psr & PSR_PS);
119 int code;
120 vm_fault_t fault;
121 unsigned int flags = FAULT_FLAG_DEFAULT;
122
123 if (text_fault)
124 address = regs->pc;
125
126 /*
127 * We fault-in kernel-space virtual memory on-demand. The
128 * 'reference' page table is init_mm.pgd.
129 *
130 * NOTE! We MUST NOT take any locks for this case. We may
131 * be in an interrupt or a critical region, and should
132 * only copy the information from the master page table,
133 * nothing more.
134 */
135 code = SEGV_MAPERR;
136 if (address >= TASK_SIZE)
137 goto vmalloc_fault;
138
139 /*
140 * If we're in an interrupt or have no user
141 * context, we must not take the fault..
142 */
143 if (pagefault_disabled() || !mm)
144 goto no_context;
145
146 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
147
148 retry:
149 mmap_read_lock(mm);
150
151 if (!from_user && address >= PAGE_OFFSET)
152 goto bad_area;
153
154 vma = find_vma(mm, address);
155 if (!vma)
156 goto bad_area;
157 if (vma->vm_start <= address)
158 goto good_area;
159 if (!(vma->vm_flags & VM_GROWSDOWN))
160 goto bad_area;
161 if (expand_stack(vma, address))
162 goto bad_area;
163 /*
164 * Ok, we have a good vm_area for this memory access, so
165 * we can handle it..
166 */
167 good_area:
168 code = SEGV_ACCERR;
169 if (write) {
170 if (!(vma->vm_flags & VM_WRITE))
171 goto bad_area;
172 } else {
173 /* Allow reads even for write-only mappings */
174 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
175 goto bad_area;
176 }
177
178 if (from_user)
179 flags |= FAULT_FLAG_USER;
180 if (write)
181 flags |= FAULT_FLAG_WRITE;
182
183 /*
184 * If for any reason at all we couldn't handle the fault,
185 * make sure we exit gracefully rather than endlessly redo
186 * the fault.
187 */
188 fault = handle_mm_fault(vma, address, flags, regs);
189
190 if (fault_signal_pending(fault, regs)) {
191 if (!from_user)
192 goto no_context;
193 return;
194 }
195
196 /* The fault is fully completed (including releasing mmap lock) */
197 if (fault & VM_FAULT_COMPLETED)
198 return;
199
200 if (unlikely(fault & VM_FAULT_ERROR)) {
201 if (fault & VM_FAULT_OOM)
202 goto out_of_memory;
203 else if (fault & VM_FAULT_SIGSEGV)
204 goto bad_area;
205 else if (fault & VM_FAULT_SIGBUS)
206 goto do_sigbus;
207 BUG();
208 }
209
210 if (fault & VM_FAULT_RETRY) {
211 flags |= FAULT_FLAG_TRIED;
212
213 /* No need to mmap_read_unlock(mm) as we would
214 * have already released it in __lock_page_or_retry
215 * in mm/filemap.c.
216 */
217
218 goto retry;
219 }
220
221 mmap_read_unlock(mm);
222 return;
223
224 /*
225 * Something tried to access memory that isn't in our memory map..
226 * Fix it, but check if it's kernel or user first..
227 */
228 bad_area:
229 mmap_read_unlock(mm);
230
231 bad_area_nosemaphore:
232 /* User mode accesses just cause a SIGSEGV */
233 if (from_user) {
234 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
235 return;
236 }
237
238 /* Is this in ex_table? */
239 no_context:
240 if (!from_user) {
241 const struct exception_table_entry *entry;
242
243 entry = search_exception_tables(regs->pc);
244 #ifdef DEBUG_EXCEPTIONS
245 printk("Exception: PC<%08lx> faddr<%08lx>\n",
246 regs->pc, address);
247 printk("EX_TABLE: insn<%08lx> fixup<%08x>\n",
248 regs->pc, entry->fixup);
249 #endif
250 regs->pc = entry->fixup;
251 regs->npc = regs->pc + 4;
252 return;
253 }
254
255 unhandled_fault(address, tsk, regs);
256
257 /*
258 * We ran out of memory, or some other thing happened to us that made
259 * us unable to handle the page fault gracefully.
260 */
261 out_of_memory:
262 mmap_read_unlock(mm);
263 if (from_user) {
264 pagefault_out_of_memory();
265 return;
266 }
267 goto no_context;
268
269 do_sigbus:
270 mmap_read_unlock(mm);
271 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
272 if (!from_user)
273 goto no_context;
274
275 vmalloc_fault:
276 {
277 /*
278 * Synchronize this task's top level page-table
279 * with the 'reference' page table.
280 */
281 int offset = pgd_index(address);
282 pgd_t *pgd, *pgd_k;
283 p4d_t *p4d, *p4d_k;
284 pud_t *pud, *pud_k;
285 pmd_t *pmd, *pmd_k;
286
287 pgd = tsk->active_mm->pgd + offset;
288 pgd_k = init_mm.pgd + offset;
289
290 if (!pgd_present(*pgd)) {
291 if (!pgd_present(*pgd_k))
292 goto bad_area_nosemaphore;
293 pgd_val(*pgd) = pgd_val(*pgd_k);
294 return;
295 }
296
297 p4d = p4d_offset(pgd, address);
298 pud = pud_offset(p4d, address);
299 pmd = pmd_offset(pud, address);
300
301 p4d_k = p4d_offset(pgd_k, address);
302 pud_k = pud_offset(p4d_k, address);
303 pmd_k = pmd_offset(pud_k, address);
304
305 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
306 goto bad_area_nosemaphore;
307
308 *pmd = *pmd_k;
309 return;
310 }
311 }
312
313 /* This always deals with user addresses. */
force_user_fault(unsigned long address,int write)314 static void force_user_fault(unsigned long address, int write)
315 {
316 struct vm_area_struct *vma;
317 struct task_struct *tsk = current;
318 struct mm_struct *mm = tsk->mm;
319 unsigned int flags = FAULT_FLAG_USER;
320 int code;
321
322 code = SEGV_MAPERR;
323
324 mmap_read_lock(mm);
325 vma = find_vma(mm, address);
326 if (!vma)
327 goto bad_area;
328 if (vma->vm_start <= address)
329 goto good_area;
330 if (!(vma->vm_flags & VM_GROWSDOWN))
331 goto bad_area;
332 if (expand_stack(vma, address))
333 goto bad_area;
334 good_area:
335 code = SEGV_ACCERR;
336 if (write) {
337 if (!(vma->vm_flags & VM_WRITE))
338 goto bad_area;
339 flags |= FAULT_FLAG_WRITE;
340 } else {
341 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
342 goto bad_area;
343 }
344 switch (handle_mm_fault(vma, address, flags, NULL)) {
345 case VM_FAULT_SIGBUS:
346 case VM_FAULT_OOM:
347 goto do_sigbus;
348 }
349 mmap_read_unlock(mm);
350 return;
351 bad_area:
352 mmap_read_unlock(mm);
353 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
354 return;
355
356 do_sigbus:
357 mmap_read_unlock(mm);
358 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
359 }
360
check_stack_aligned(unsigned long sp)361 static void check_stack_aligned(unsigned long sp)
362 {
363 if (sp & 0x7UL)
364 force_sig(SIGILL);
365 }
366
window_overflow_fault(void)367 void window_overflow_fault(void)
368 {
369 unsigned long sp;
370
371 sp = current_thread_info()->rwbuf_stkptrs[0];
372 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
373 force_user_fault(sp + 0x38, 1);
374 force_user_fault(sp, 1);
375
376 check_stack_aligned(sp);
377 }
378
window_underflow_fault(unsigned long sp)379 void window_underflow_fault(unsigned long sp)
380 {
381 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
382 force_user_fault(sp + 0x38, 0);
383 force_user_fault(sp, 0);
384
385 check_stack_aligned(sp);
386 }
387
window_ret_fault(struct pt_regs * regs)388 void window_ret_fault(struct pt_regs *regs)
389 {
390 unsigned long sp;
391
392 sp = regs->u_regs[UREG_FP];
393 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
394 force_user_fault(sp + 0x38, 0);
395 force_user_fault(sp, 0);
396
397 check_stack_aligned(sp);
398 }
399