aboutsummaryrefslogtreecommitdiff
path: root/arch/sparc/mm/fault_32.c
blob: c399e7b3b035250d66ed4522d2da190dc6169aa3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
/*
 * fault.c:  Page fault handlers for the Sparc.
 *
 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
 */

#include <asm/head.h>

#include <linux/string.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/threads.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/perf_event.h>
#include <linux/interrupt.h>
#include <linux/kdebug.h>
#include <linux/uaccess.h>

#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/openprom.h>
#include <asm/oplib.h>
#include <asm/setup.h>
#include <asm/smp.h>
#include <asm/traps.h>

#include "mm_32.h"

int show_unhandled_signals = 1;

static void __noreturn unhandled_fault(unsigned long address,
				       struct task_struct *tsk,
				       struct pt_regs *regs)
{
	if ((unsigned long) address < PAGE_SIZE) {
		printk(KERN_ALERT
		    "Unable to handle kernel NULL pointer dereference\n");
	} else {
		printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
		       address);
	}
	printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
		(tsk->mm ? tsk->mm->context : tsk->active_mm->context));
	printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
		(tsk->mm ? (unsigned long) tsk->mm->pgd :
			(unsigned long) tsk->active_mm->pgd));
	die_if_kernel("Oops", regs);
}

asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
			    unsigned long address)
{
	struct pt_regs regs;
	unsigned long g2;
	unsigned int insn;
	int i;

	i = search_extables_range(ret_pc, &g2);
	switch (i) {
	case 3:
		/* load & store will be handled by fixup */
		return 3;

	case 1:
		/* store will be handled by fixup, load will bump out */
		/* for _to_ macros */
		insn = *((unsigned int *) pc);
		if ((insn >> 21) & 1)
			return 1;
		break;

	case 2:
		/* load will be handled by fixup, store will bump out */
		/* for _from_ macros */
		insn = *((unsigned int *) pc);
		if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
			return 2;
		break;

	default:
		break;
	}

	memset(&regs, 0, sizeof(regs));
	regs.pc = pc;
	regs.npc = pc + 4;
	__asm__ __volatile__(
		"rd %%psr, %0\n\t"
		"nop\n\t"
		"nop\n\t"
		"nop\n" : "=r" (regs.psr));
	unhandled_fault(address, current, &regs);

	/* Not reached */
	return 0;
}

static inline void
show_signal_msg(struct pt_regs *regs, int sig, int code,
		unsigned long address, struct task_struct *tsk)
{
	if (!unhandled_signal(tsk, sig))
		return;

	if (!printk_ratelimit())
		return;

	printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
	       task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
	       tsk->comm, task_pid_nr(tsk), address,
	       (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
	       (void *)regs->u_regs[UREG_FP], code);

	print_vma_addr(KERN_CONT " in ", regs->pc);

	printk(KERN_CONT "\n");
}

static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
			       unsigned long addr)
{
	siginfo_t info;

	info.si_signo = sig;
	info.si_code = code;
	info.si_errno = 0;
	info.si_addr = (void __user *) addr;
	info.si_trapno = 0;

	if (unlikely(show_unhandled_signals))
		show_signal_msg(regs, sig, info.si_code,
				addr, current);

	force_sig_info (sig, &info, current);
}

static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
{
	unsigned int insn;

	if (text_fault)
		return regs->pc;

	if (regs->psr & PSR_PS)
		insn = *(unsigned int *) regs->pc;
	else
		__get_user(insn, (unsigned int *) regs->pc);

	return safe_compute_effective_address(regs, insn);
}

static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
				      int text_fault)
{
	unsigned long addr = compute_si_addr(regs, text_fault);

	__do_fault_siginfo(code, sig, regs, addr);
}

asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
			       unsigned long address)
{
	struct vm_area_struct *vma;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	unsigned int fixup;
	unsigned long g2;
	int from_user = !(regs->psr & PSR_PS);
	int fault, code;
	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

	if (text_fault)
		address = regs->pc;

	/*
	 * We fault-in kernel-space virtual memory on-demand. The
	 * 'reference' page table is init_mm.pgd.
	 *
	 * NOTE! We MUST NOT take any locks for this case. We may
	 * be in an interrupt or a critical region, and should
	 * only copy the information from the master page table,
	 * nothing more.
	 */
	code = SEGV_MAPERR;
	if (address >= TASK_SIZE)
		goto vmalloc_fault;

	/*
	 * If we're in an interrupt or have no user
	 * context, we must not take the fault..
	 */
	if (pagefault_disabled() || !mm)
		goto no_context;

	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);

retry:
	down_read(&mm->mmap_sem);

	if (!from_user && address >= PAGE_OFFSET)
		goto bad_area;

	vma = find_vma(mm, address);
	if (!vma)
		goto bad_area;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto bad_area;
	if (expand_stack(vma, address))
		goto bad_area;
	/*
	 * Ok, we have a good vm_area for this memory access, so
	 * we can handle it..
	 */
good_area:
	code = SEGV_ACCERR;
	if (write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
	} else {
		/* Allow reads even for write-only mappings */
		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
			goto bad_area;
	}

	if (from_user)
		flags |= FAULT_FLAG_USER;
	if (write)
		flags |= FAULT_FLAG_WRITE;

	/*
	 * If for any reason at all we couldn't handle the fault,
	 * make sure we exit gracefully rather than endlessly redo
	 * the fault.
	 */
	fault = handle_mm_fault(mm, vma, address, flags);

	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
		return;

	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGSEGV)
			goto bad_area;
		else if (fault & VM_FAULT_SIGBUS)
			goto do_sigbus;
		BUG();
	}

	if (flags & FAULT_FLAG_ALLOW_RETRY) {
		if (fault & VM_FAULT_MAJOR) {
			current->maj_flt++;
			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
				      1, regs, address);
		} else {
			current->min_flt++;
			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
				      1, regs, address);
		}
		if (fault & VM_FAULT_RETRY) {
			flags &= ~FAULT_FLAG_ALLOW_RETRY;
			flags |= FAULT_FLAG_TRIED;

			/* No need to up_read(&mm->mmap_sem) as we would
			 * have already released it in __lock_page_or_retry
			 * in mm/filemap.c.
			 */

			goto retry;
		}
	}

	up_read(&mm->mmap_sem);
	return;

	/*
	 * Something tried to access memory that isn't in our memory map..
	 * Fix it, but check if it's kernel or user first..
	 */
bad_area:
	up_read(&mm->mmap_sem);

bad_area_nosemaphore:
	/* User mode accesses just cause a SIGSEGV */
	if (from_user) {
		do_fault_siginfo(code, SIGSEGV, regs, text_fault);
		return;
	}

	/* Is this in ex_table? */
no_context:
	g2 = regs->u_regs[UREG_G2];
	if (!from_user) {
		fixup = search_extables_range(regs->pc, &g2);
		/* Values below 10 are reserved for other things */
		if (fixup > 10) {
			extern const unsigned __memset_start[];
			extern const unsigned __memset_end[];
			extern const unsigned __csum_partial_copy_start[];
			extern const unsigned __csum_partial_copy_end[];

#ifdef DEBUG_EXCEPTIONS
			printk("Exception: PC<%08lx> faddr<%08lx>\n",
			       regs->pc, address);
			printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
				regs->pc, fixup, g2);
#endif
			if ((regs->pc >= (unsigned long)__memset_start &&
			     regs->pc < (unsigned long)__memset_end) ||
			    (regs->pc >= (unsigned long)__csum_partial_copy_start &&
			     regs->pc < (unsigned long)__csum_partial_copy_end)) {
				regs->u_regs[UREG_I4] = address;
				regs->u_regs[UREG_I5] = regs->pc;
			}
			regs->u_regs[UREG_G2] = g2;
			regs->pc = fixup;
			regs->npc = regs->pc + 4;
			return;
		}
	}

	unhandled_fault(address, tsk, regs);
	do_exit(SIGKILL);

/*
 * We ran out of memory, or some other thing happened to us that made
 * us unable to handle the page fault gracefully.
 */
out_of_memory:
	up_read(&mm->mmap_sem);
	if (from_user) {
		pagefault_out_of_memory();
		return;
	}
	goto no_context;

do_sigbus:
	up_read(&mm->mmap_sem);
	do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
	if (!from_user)
		goto no_context;

vmalloc_fault:
	{
		/*
		 * Synchronize this task's top level page-table
		 * with the 'reference' page table.
		 */
		int offset = pgd_index(address);
		pgd_t *pgd, *pgd_k;
		pmd_t *pmd, *pmd_k;

		pgd = tsk->active_mm->pgd + offset;
		pgd_k = init_mm.pgd + offset;

		if (!pgd_present(*pgd)) {
			if (!pgd_present(*pgd_k))
				goto bad_area_nosemaphore;
			pgd_val(*pgd) = pgd_val(*pgd_k);
			return;
		}

		pmd = pmd_offset(pgd, address);
		pmd_k = pmd_offset(pgd_k, address);

		if (pmd_present(*pmd) || !pmd_present(*pmd_k))
			goto bad_area_nosemaphore;

		*pmd = *pmd_k;
		return;
	}
}

/* This always deals with user addresses. */
static void force_user_fault(unsigned long address, int write)
{
	struct vm_area_struct *vma;
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->mm;
	unsigned int flags = FAULT_FLAG_USER;
	int code;

	code = SEGV_MAPERR;

	down_read(&mm->mmap_sem);
	vma = find_vma(mm, address);
	if (!vma)
		goto bad_area;
	if (vma->vm_start <= address)
		goto good_area;
	if (!(vma->vm_flags & VM_GROWSDOWN))
		goto bad_area;
	if (expand_stack(vma, address))
		goto bad_area;
good_area:
	code = SEGV_ACCERR;
	if (write) {
		if (!(vma->vm_flags & VM_WRITE))
			goto bad_area;
		flags |= FAULT_FLAG_WRITE;
	} else {
		if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
			goto bad_area;
	}
	switch (handle_mm_fault(mm, vma, address, flags)) {
	case VM_FAULT_SIGBUS:
	case VM_FAULT_OOM:
		goto do_sigbus;
	}
	up_read(&mm->mmap_sem);
	return;
bad_area:
	up_read(&mm->mmap_sem);
	__do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
	return;

do_sigbus:
	up_read(&mm->mmap_sem);
	__do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
}

static void check_stack_aligned(unsigned long sp)
{
	if (sp & 0x7UL)
		force_sig(SIGILL, current);
}

void window_overflow_fault(void)
{
	unsigned long sp;

	sp = current_thread_info()->rwbuf_stkptrs[0];
	if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
		force_user_fault(sp + 0x38, 1);
	force_user_fault(sp, 1);

	check_stack_aligned(sp);
}

void window_underflow_fault(unsigned long sp)
{
	if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
		force_user_fault(sp + 0x38, 0);
	force_user_fault(sp, 0);

	check_stack_aligned(sp);
}

void window_ret_fault(struct pt_regs *regs)
{
	unsigned long sp;

	sp = regs->u_regs[UREG_FP];
	if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
		force_user_fault(sp + 0x38, 0);
	force_user_fault(sp, 0);

	check_stack_aligned(sp);
}