summaryrefslogtreecommitdiffstats
path: root/arch/unicore32/mm/fault.c
blob: a9bd08fbe5884af2781f6c17e490ef2a0355a3ff (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
469
470
471
472
473
474
475
476
477
478
479
480
481
482
// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/arch/unicore32/mm/fault.c
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 * Copyright (C) 2001-2010 GUAN Xue-tao
 */
#include <linux/extable.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/hardirq.h>
#include <linux/init.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/page-flags.h>
#include <linux/sched/signal.h>
#include <linux/io.h>

#include <asm/pgtable.h>
#include <asm/tlbflush.h>

/*
 * Fault status register encodings.  We steal bit 31 for our own purposes.
 */
#define FSR_LNX_PF		(1 << 31)

static inline int fsr_fs(unsigned int fsr)
{
	/* xyabcde will be abcde+xy */
	return (fsr & 31) + ((fsr & (3 << 5)) >> 5);
}

/*
 * This is useful to dump out the page tables associated with
 * 'addr' in mm 'mm'.
 */
void show_pte(struct mm_struct *mm, unsigned long addr)
{
	pgd_t *pgd;

	if (!mm)
		mm = &init_mm;

	printk(KERN_ALERT "pgd = %p\n", mm->pgd);
	pgd = pgd_offset(mm, addr);
	printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));

	do {
		pmd_t *pmd;
		pte_t *pte;

		if (pgd_none(*pgd))
			break;

		if (pgd_bad(*pgd)) {
			printk("(bad)");
			break;
		}

		pmd = pmd_offset((pud_t *) pgd, addr);
		if (PTRS_PER_PMD != 1)
			printk(", *pmd=%08lx", pmd_val(*pmd));

		if (pmd_none(*pmd))
			break;

		if (pmd_bad(*pmd)) {
			printk("(bad)");
			break;
		}

		/* We must not map this if we have highmem enabled */
		if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
			break;

		pte = pte_offset_map(pmd, addr);
		printk(", *pte=%08lx", pte_val(*pte));
		pte_unmap(pte);
	} while (0);

	printk("\n");
}

/*
 * Oops.  The kernel tried to access some page that wasn't present.
 */
static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
		unsigned int fsr, struct pt_regs *regs)
{
	/*
	 * Are we prepared to handle this kernel fault?
	 */
	if (fixup_exception(regs))
		return;

	/*
	 * No handler, we'll have to terminate things with extreme prejudice.
	 */
	bust_spinlocks(1);
	printk(KERN_ALERT
	       "Unable to handle kernel %s at virtual address %08lx\n",
	       (addr < PAGE_SIZE) ? "NULL pointer dereference" :
	       "paging request", addr);

	show_pte(mm, addr);
	die("Oops", regs, fsr);
	bust_spinlocks(0);
	do_exit(SIGKILL);
}

/*
 * Something tried to access memory that isn't in our memory map..
 * User mode accesses just cause a SIGSEGV
 */
static void __do_user_fault(unsigned long addr, unsigned int fsr,
			    unsigned int sig, int code,	struct pt_regs *regs)
{
	struct task_struct *tsk = current;

	tsk->thread.address = addr;
	tsk->thread.error_code = fsr;
	tsk->thread.trap_no = 14;
	force_sig_fault(sig, code, (void __user *)addr);
}

void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	struct task_struct *tsk = current;
	struct mm_struct *mm = tsk->active_mm;

	/*
	 * If we are in kernel mode at this point, we
	 * have no context to handle this fault with.
	 */
	if (user_mode(regs))
		__do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
	else
		__do_kernel_fault(mm, addr, fsr, regs);
}

#define VM_FAULT_BADMAP		0x010000
#define VM_FAULT_BADACCESS	0x020000

/*
 * Check that the permissions on the VMA allow for the fault which occurred.
 * If we encountered a write fault, we must have write permission, otherwise
 * we allow any permission.
 */
static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
{
	unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;

	if (!(fsr ^ 0x12))	/* write? */
		mask = VM_WRITE;
	if (fsr & FSR_LNX_PF)
		mask = VM_EXEC;

	return vma->vm_flags & mask ? false : true;
}

static vm_fault_t __do_pf(struct mm_struct *mm, unsigned long addr,
		unsigned int fsr, unsigned int flags, struct task_struct *tsk)
{
	struct vm_area_struct *vma;
	vm_fault_t fault;

	vma = find_vma(mm, addr);
	fault = VM_FAULT_BADMAP;
	if (unlikely(!vma))
		goto out;
	if (unlikely(vma->vm_start > addr))
		goto check_stack;

	/*
	 * Ok, we have a good vm_area for this
	 * memory access, so we can handle it.
	 */
good_area:
	if (access_error(fsr, vma)) {
		fault = VM_FAULT_BADACCESS;
		goto out;
	}

	/*
	 * 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(vma, addr & PAGE_MASK, flags);
	return fault;

check_stack:
	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
		goto good_area;
out:
	return fault;
}

static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	struct task_struct *tsk;
	struct mm_struct *mm;
	int sig, code;
	vm_fault_t fault;
	unsigned int flags = FAULT_FLAG_DEFAULT;

	tsk = current;
	mm = tsk->mm;

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

	if (user_mode(regs))
		flags |= FAULT_FLAG_USER;
	if (!(fsr ^ 0x12))
		flags |= FAULT_FLAG_WRITE;

	/*
	 * As per x86, we may deadlock here.  However, since the kernel only
	 * validly references user space from well defined areas of the code,
	 * we can bug out early if this is from code which shouldn't.
	 */
	if (!down_read_trylock(&mm->mmap_sem)) {
		if (!user_mode(regs)
		    && !search_exception_tables(regs->UCreg_pc))
			goto no_context;
retry:
		down_read(&mm->mmap_sem);
	} else {
		/*
		 * The above down_read_trylock() might have succeeded in
		 * which case, we'll have missed the might_sleep() from
		 * down_read()
		 */
		might_sleep();
#ifdef CONFIG_DEBUG_VM
		if (!user_mode(regs) &&
		    !search_exception_tables(regs->UCreg_pc))
			goto no_context;
#endif
	}

	fault = __do_pf(mm, addr, fsr, flags, tsk);

	/* If we need to retry but a fatal signal is pending, handle the
	 * signal first. We do not need to release the mmap_sem because
	 * it would already be released in __lock_page_or_retry in
	 * mm/filemap.c. */
	if (fault_signal_pending(fault, regs))
		return 0;

	if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
		if (fault & VM_FAULT_MAJOR)
			tsk->maj_flt++;
		else
			tsk->min_flt++;
		if (fault & VM_FAULT_RETRY) {
			flags |= FAULT_FLAG_TRIED;
			goto retry;
		}
	}

	up_read(&mm->mmap_sem);

	/*
	 * Handle the "normal" case first - VM_FAULT_MAJOR
	 */
	if (likely(!(fault &
	       (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
		return 0;

	/*
	 * If we are in kernel mode at this point, we
	 * have no context to handle this fault with.
	 */
	if (!user_mode(regs))
		goto no_context;

	if (fault & VM_FAULT_OOM) {
		/*
		 * We ran out of memory, call the OOM killer, and return to
		 * userspace (which will retry the fault, or kill us if we
		 * got oom-killed)
		 */
		pagefault_out_of_memory();
		return 0;
	}

	if (fault & VM_FAULT_SIGBUS) {
		/*
		 * We had some memory, but were unable to
		 * successfully fix up this page fault.
		 */
		sig = SIGBUS;
		code = BUS_ADRERR;
	} else {
		/*
		 * Something tried to access memory that
		 * isn't in our memory map..
		 */
		sig = SIGSEGV;
		code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR;
	}

	__do_user_fault(addr, fsr, sig, code, regs);
	return 0;

no_context:
	__do_kernel_fault(mm, addr, fsr, regs);
	return 0;
}

/*
 * First Level Translation Fault Handler
 *
 * We enter here because the first level page table doesn't contain
 * a valid entry for the address.
 *
 * If the address is in kernel space (>= TASK_SIZE), then we are
 * probably faulting in the vmalloc() area.
 *
 * If the init_task's first level page tables contains the relevant
 * entry, we copy the it to this task.  If not, we send the process
 * a signal, fixup the exception, or oops the kernel.
 *
 * 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.
 */
static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	unsigned int index;
	pgd_t *pgd, *pgd_k;
	pmd_t *pmd, *pmd_k;

	if (addr < TASK_SIZE)
		return do_pf(addr, fsr, regs);

	if (user_mode(regs))
		goto bad_area;

	index = pgd_index(addr);

	pgd = cpu_get_pgd() + index;
	pgd_k = init_mm.pgd + index;

	if (pgd_none(*pgd_k))
		goto bad_area;

	pmd_k = pmd_offset((pud_t *) pgd_k, addr);
	pmd = pmd_offset((pud_t *) pgd, addr);

	if (pmd_none(*pmd_k))
		goto bad_area;

	set_pmd(pmd, *pmd_k);
	flush_pmd_entry(pmd);
	return 0;

bad_area:
	do_bad_area(addr, fsr, regs);
	return 0;
}

/*
 * This abort handler always returns "fault".
 */
static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	return 1;
}

static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
{
	unsigned int res1, res2;

	printk("dabt exception but no error!\n");

	__asm__ __volatile__(
			"mff %0,f0\n"
			"mff %1,f1\n"
			: "=r"(res1), "=r"(res2)
			:
			: "memory");

	printk(KERN_EMERG "r0 :%08x  r1 :%08x\n", res1, res2);
	panic("shut up\n");
	return 0;
}

static struct fsr_info {
	int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs);
	int sig;
	int code;
	const char *name;
} fsr_info[] = {
	/*
	 * The following are the standard Unicore-I and UniCore-II aborts.
	 */
	{ do_good,	SIGBUS,  0,		"no error"		},
	{ do_bad,	SIGBUS,  BUS_ADRALN,	"alignment exception"	},
	{ do_bad,	SIGBUS,  BUS_OBJERR,	"external exception"	},
	{ do_bad,	SIGBUS,  0,		"burst operation"	},
	{ do_bad,	SIGBUS,  0,		"unknown 00100"		},
	{ do_ifault,	SIGSEGV, SEGV_MAPERR,	"2nd level pt non-exist"},
	{ do_bad,	SIGBUS,  0,		"2nd lvl large pt non-exist" },
	{ do_bad,	SIGBUS,  0,		"invalid pte"		},
	{ do_pf,	SIGSEGV, SEGV_MAPERR,	"page miss"		},
	{ do_bad,	SIGBUS,  0,		"middle page miss"	},
	{ do_bad,	SIGBUS,	 0,		"large page miss"	},
	{ do_pf,	SIGSEGV, SEGV_MAPERR,	"super page (section) miss" },
	{ do_bad,	SIGBUS,  0,		"unknown 01100"		},
	{ do_bad,	SIGBUS,  0,		"unknown 01101"		},
	{ do_bad,	SIGBUS,  0,		"unknown 01110"		},
	{ do_bad,	SIGBUS,  0,		"unknown 01111"		},
	{ do_bad,	SIGBUS,  0,		"addr: up 3G or IO"	},
	{ do_pf,	SIGSEGV, SEGV_ACCERR,	"read unreadable addr"	},
	{ do_pf,	SIGSEGV, SEGV_ACCERR,	"write unwriteable addr"},
	{ do_pf,	SIGSEGV, SEGV_ACCERR,	"exec unexecutable addr"},
	{ do_bad,	SIGBUS,  0,		"unknown 10100"		},
	{ do_bad,	SIGBUS,  0,		"unknown 10101"		},
	{ do_bad,	SIGBUS,  0,		"unknown 10110"		},
	{ do_bad,	SIGBUS,  0,		"unknown 10111"		},
	{ do_bad,	SIGBUS,  0,		"unknown 11000"		},
	{ do_bad,	SIGBUS,  0,		"unknown 11001"		},
	{ do_bad,	SIGBUS,  0,		"unknown 11010"		},
	{ do_bad,	SIGBUS,  0,		"unknown 11011"		},
	{ do_bad,	SIGBUS,  0,		"unknown 11100"		},
	{ do_bad,	SIGBUS,  0,		"unknown 11101"		},
	{ do_bad,	SIGBUS,  0,		"unknown 11110"		},
	{ do_bad,	SIGBUS,  0,		"unknown 11111"		}
};

void __init hook_fault_code(int nr,
		int (*fn) (unsigned long, unsigned int, struct pt_regs *),
		int sig, int code, const char *name)
{
	if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
		BUG();

	fsr_info[nr].fn   = fn;
	fsr_info[nr].sig  = sig;
	fsr_info[nr].code = code;
	fsr_info[nr].name = name;
}

/*
 * Dispatch a data abort to the relevant handler.
 */
asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr,
			struct pt_regs *regs)
{
	const struct fsr_info *inf = fsr_info + fsr_fs(fsr);

	if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
		return;

	printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
	       inf->name, fsr, addr);

	uc32_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
			fsr, 0);
}

asmlinkage void do_PrefetchAbort(unsigned long addr,
			unsigned int ifsr, struct pt_regs *regs)
{
	const struct fsr_info *inf = fsr_info + fsr_fs(ifsr);

	if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
		return;

	printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
	       inf->name, ifsr, addr);

	uc32_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
			ifsr, 0);
}