1
/*
2
 * Kernel Debugger Architecture Independent Support Functions
3
 *
4
 * This file is subject to the terms and conditions of the GNU General Public
5
 * License.  See the file "COPYING" in the main directory of this archive
6
 * for more details.
7
 *
8
 * Copyright (c) 1999-2004 Silicon Graphics, Inc.  All Rights Reserved.
9
 * Copyright (c) 2009 Wind River Systems, Inc.  All Rights Reserved.
10
 * 03/02/13    added new 2.5 kallsyms <[email protected]>
11
 */
12

13
#include <linux/types.h>
14
#include <linux/sched.h>
15
#include <linux/mm.h>
16
#include <linux/kallsyms.h>
17
#include <linux/stddef.h>
18
#include <linux/vmalloc.h>
19
#include <linux/ptrace.h>
20
#include <linux/highmem.h>
21
#include <linux/hardirq.h>
22
#include <linux/delay.h>
23
#include <linux/uaccess.h>
24
#include <linux/kdb.h>
25
#include <linux/slab.h>
26
#include <linux/string.h>
27
#include <linux/ctype.h>
28
#include "kdb_private.h"
29

30
/*
31
 * kdbgetsymval - Return the address of the given symbol.
32
 *
33
 * Parameters:
34
 *	symname	Character string containing symbol name
35
 *      symtab  Structure to receive results
36
 * Returns:
37
 *	0	Symbol not found, symtab zero filled
38
 *	1	Symbol mapped to module/symbol/section, data in symtab
39
 */
40
int kdbgetsymval(const char *symname, kdb_symtab_t *symtab)
41
{
42
	kdb_dbg_printf(AR, "symname=%s, symtab=%px\n", symname, symtab);
43
	memset(symtab, 0, sizeof(*symtab));
44
	symtab->sym_start = kallsyms_lookup_name(symname);
45
	if (symtab->sym_start) {
46
		kdb_dbg_printf(AR, "returns 1, symtab->sym_start=0x%lx\n",
47
			       symtab->sym_start);
48
		return 1;
49
	}
50
	kdb_dbg_printf(AR, "returns 0\n");
51
	return 0;
52
}
53
EXPORT_SYMBOL(kdbgetsymval);
54

55
/**
56
 * kdbnearsym() - Return the name of the symbol with the nearest address
57
 *                less than @addr.
58
 * @addr: Address to check for near symbol
59
 * @symtab: Structure to receive results
60
 *
61
 * WARNING: This function may return a pointer to a single statically
62
 * allocated buffer (namebuf). kdb's unusual calling context (single
63
 * threaded, all other CPUs halted) provides us sufficient locking for
64
 * this to be safe. The only constraint imposed by the static buffer is
65
 * that the caller must consume any previous reply prior to another call
66
 * to lookup a new symbol.
67
 *
68
 * Note that, strictly speaking, some architectures may re-enter the kdb
69
 * trap if the system turns out to be very badly damaged and this breaks
70
 * the single-threaded assumption above. In these circumstances successful
71
 * continuation and exit from the inner trap is unlikely to work and any
72
 * user attempting this receives a prominent warning before being allowed
73
 * to progress. In these circumstances we remain memory safe because
74
 * namebuf[KSYM_NAME_LEN-1] will never change from '\0' although we do
75
 * tolerate the possibility of garbled symbol display from the outer kdb
76
 * trap.
77
 *
78
 * Return:
79
 * * 0 - No sections contain this address, symtab zero filled
80
 * * 1 - Address mapped to module/symbol/section, data in symtab
81
 */
82
int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
83
{
84
	int ret = 0;
85
	unsigned long symbolsize = 0;
86
	unsigned long offset = 0;
87
	static char namebuf[KSYM_NAME_LEN];
88

89
	kdb_dbg_printf(AR, "addr=0x%lx, symtab=%px\n", addr, symtab);
90
	memset(symtab, 0, sizeof(*symtab));
91

92
	if (addr < 4096)
93
		goto out;
94

95
	symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
96
				(char **)(&symtab->mod_name), namebuf);
97
	if (offset > 8*1024*1024) {
98
		symtab->sym_name = NULL;
99
		addr = offset = symbolsize = 0;
100
	}
101
	symtab->sym_start = addr - offset;
102
	symtab->sym_end = symtab->sym_start + symbolsize;
103
	ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';
104

105
	if (symtab->mod_name == NULL)
106
		symtab->mod_name = "kernel";
107
	kdb_dbg_printf(AR, "returns %d symtab->sym_start=0x%lx, symtab->mod_name=%px, symtab->sym_name=%px (%s)\n",
108
		       ret, symtab->sym_start, symtab->mod_name, symtab->sym_name, symtab->sym_name);
109
out:
110
	return ret;
111
}
112

113
static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];
114

115
/*
116
 * kallsyms_symbol_complete
117
 *
118
 * Parameters:
119
 *	prefix_name	prefix of a symbol name to lookup
120
 *	max_len		maximum length that can be returned
121
 * Returns:
122
 *	Number of symbols which match the given prefix.
123
 * Notes:
124
 *	prefix_name is changed to contain the longest unique prefix that
125
 *	starts with this prefix (tab completion).
126
 */
127
int kallsyms_symbol_complete(char *prefix_name, int max_len)
128
{
129
	loff_t pos = 0;
130
	int prefix_len = strlen(prefix_name), prev_len = 0;
131
	int i, number = 0;
132
	const char *name;
133

134
	while ((name = kdb_walk_kallsyms(&pos))) {
135
		if (strncmp(name, prefix_name, prefix_len) == 0) {
136
			strscpy(ks_namebuf, name, sizeof(ks_namebuf));
137
			/* Work out the longest name that matches the prefix */
138
			if (++number == 1) {
139
				prev_len = min_t(int, max_len-1,
140
						 strlen(ks_namebuf));
141
				memcpy(ks_namebuf_prev, ks_namebuf, prev_len);
142
				ks_namebuf_prev[prev_len] = '\0';
143
				continue;
144
			}
145
			for (i = 0; i < prev_len; i++) {
146
				if (ks_namebuf[i] != ks_namebuf_prev[i]) {
147
					prev_len = i;
148
					ks_namebuf_prev[i] = '\0';
149
					break;
150
				}
151
			}
152
		}
153
	}
154
	if (prev_len > prefix_len)
155
		memcpy(prefix_name, ks_namebuf_prev, prev_len+1);
156
	return number;
157
}
158

159
/*
160
 * kallsyms_symbol_next
161
 *
162
 * Parameters:
163
 *	prefix_name	prefix of a symbol name to lookup
164
 *	flag	0 means search from the head, 1 means continue search.
165
 *	buf_size	maximum length that can be written to prefix_name
166
 *			buffer
167
 * Returns:
168
 *	1 if a symbol matches the given prefix.
169
 *	0 if no string found
170
 */
171
int kallsyms_symbol_next(char *prefix_name, int flag, int buf_size)
172
{
173
	int prefix_len = strlen(prefix_name);
174
	static loff_t pos;
175
	const char *name;
176

177
	if (!flag)
178
		pos = 0;
179

180
	while ((name = kdb_walk_kallsyms(&pos))) {
181
		if (!strncmp(name, prefix_name, prefix_len))
182
			return strscpy(prefix_name, name, buf_size);
183
	}
184
	return 0;
185
}
186

187
/*
188
 * kdb_symbol_print - Standard method for printing a symbol name and offset.
189
 * Inputs:
190
 *	addr	Address to be printed.
191
 *	symtab	Address of symbol data, if NULL this routine does its
192
 *		own lookup.
193
 *	punc	Punctuation for string, bit field.
194
 * Remarks:
195
 *	The string and its punctuation is only printed if the address
196
 *	is inside the kernel, except that the value is always printed
197
 *	when requested.
198
 */
199
void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p,
200
		      unsigned int punc)
201
{
202
	kdb_symtab_t symtab, *symtab_p2;
203
	if (symtab_p) {
204
		symtab_p2 = (kdb_symtab_t *)symtab_p;
205
	} else {
206
		symtab_p2 = &symtab;
207
		kdbnearsym(addr, symtab_p2);
208
	}
209
	if (!(symtab_p2->sym_name || (punc & KDB_SP_VALUE)))
210
		return;
211
	if (punc & KDB_SP_SPACEB)
212
		kdb_printf(" ");
213
	if (punc & KDB_SP_VALUE)
214
		kdb_printf(kdb_machreg_fmt0, addr);
215
	if (symtab_p2->sym_name) {
216
		if (punc & KDB_SP_VALUE)
217
			kdb_printf(" ");
218
		if (punc & KDB_SP_PAREN)
219
			kdb_printf("(");
220
		if (strcmp(symtab_p2->mod_name, "kernel"))
221
			kdb_printf("[%s]", symtab_p2->mod_name);
222
		kdb_printf("%s", symtab_p2->sym_name);
223
		if (addr != symtab_p2->sym_start)
224
			kdb_printf("+0x%lx", addr - symtab_p2->sym_start);
225
		if (punc & KDB_SP_SYMSIZE)
226
			kdb_printf("/0x%lx",
227
				   symtab_p2->sym_end - symtab_p2->sym_start);
228
		if (punc & KDB_SP_PAREN)
229
			kdb_printf(")");
230
	}
231
	if (punc & KDB_SP_SPACEA)
232
		kdb_printf(" ");
233
	if (punc & KDB_SP_NEWLINE)
234
		kdb_printf("\n");
235
}
236

237
/*
238
 * kdb_strdup - kdb equivalent of strdup, for disasm code.
239
 * Inputs:
240
 *	str	The string to duplicate.
241
 *	type	Flags to kmalloc for the new string.
242
 * Returns:
243
 *	Address of the new string, NULL if storage could not be allocated.
244
 * Remarks:
245
 *	This is not in lib/string.c because it uses kmalloc which is not
246
 *	available when string.o is used in boot loaders.
247
 */
248
char *kdb_strdup(const char *str, gfp_t type)
249
{
250
	size_t n = strlen(str) + 1;
251
	char *s = kmalloc(n, type);
252
	if (!s)
253
		return NULL;
254
	memcpy(s, str, n);
255
	return s;
256
}
257

258
/*
259
 * kdb_strdup_dequote - same as kdb_strdup(), but trims surrounding quotes from
260
 *			the input string if present.
261
 * Remarks:
262
 *	Quotes are only removed if there is both a leading and a trailing quote.
263
 */
264
char *kdb_strdup_dequote(const char *str, gfp_t type)
265
{
266
	size_t len = strlen(str);
267
	char *s;
268

269
	if (str[0] == '"' && len > 1 && str[len - 1] == '"') {
270
		/* trim both leading and trailing quotes */
271
		str++;
272
		len -= 2;
273
	}
274

275
	len++; /* add space for NUL terminator */
276

277
	s = kmalloc(len, type);
278
	if (!s)
279
		return NULL;
280

281
	memcpy(s, str, len - 1);
282
	s[len - 1] = '\0';
283

284
	return s;
285
}
286

287
/*
288
 * kdb_getarea_size - Read an area of data.  The kdb equivalent of
289
 *	copy_from_user, with kdb messages for invalid addresses.
290
 * Inputs:
291
 *	res	Pointer to the area to receive the result.
292
 *	addr	Address of the area to copy.
293
 *	size	Size of the area.
294
 * Returns:
295
 *	0 for success, < 0 for error.
296
 */
297
int kdb_getarea_size(void *res, unsigned long addr, size_t size)
298
{
299
	int ret = copy_from_kernel_nofault((char *)res, (char *)addr, size);
300
	if (ret) {
301
		if (!KDB_STATE(SUPPRESS)) {
302
			kdb_func_printf("Bad address 0x%lx\n", addr);
303
			KDB_STATE_SET(SUPPRESS);
304
		}
305
		ret = KDB_BADADDR;
306
	} else {
307
		KDB_STATE_CLEAR(SUPPRESS);
308
	}
309
	return ret;
310
}
311

312
/*
313
 * kdb_putarea_size - Write an area of data.  The kdb equivalent of
314
 *	copy_to_user, with kdb messages for invalid addresses.
315
 * Inputs:
316
 *	addr	Address of the area to write to.
317
 *	res	Pointer to the area holding the data.
318
 *	size	Size of the area.
319
 * Returns:
320
 *	0 for success, < 0 for error.
321
 */
322
int kdb_putarea_size(unsigned long addr, void *res, size_t size)
323
{
324
	int ret = copy_to_kernel_nofault((char *)addr, (char *)res, size);
325
	if (ret) {
326
		if (!KDB_STATE(SUPPRESS)) {
327
			kdb_func_printf("Bad address 0x%lx\n", addr);
328
			KDB_STATE_SET(SUPPRESS);
329
		}
330
		ret = KDB_BADADDR;
331
	} else {
332
		KDB_STATE_CLEAR(SUPPRESS);
333
	}
334
	return ret;
335
}
336

337
/*
338
 * kdb_getphys - Read data from a physical address. Validate the
339
 *	address is in range, use kmap_local_page() to get data
340
 * 	similar to kdb_getarea() - but for phys addresses
341
 * Inputs:
342
 * 	res	Pointer to the word to receive the result
343
 * 	addr	Physical address of the area to copy
344
 * 	size	Size of the area
345
 * Returns:
346
 *	0 for success, < 0 for error.
347
 */
348
static int kdb_getphys(void *res, unsigned long addr, size_t size)
349
{
350
	unsigned long pfn;
351
	void *vaddr;
352
	struct page *page;
353

354
	pfn = (addr >> PAGE_SHIFT);
355
	if (!pfn_valid(pfn))
356
		return 1;
357
	page = pfn_to_page(pfn);
358
	vaddr = kmap_local_page(page);
359
	memcpy(res, vaddr + (addr & (PAGE_SIZE - 1)), size);
360
	kunmap_local(vaddr);
361

362
	return 0;
363
}
364

365
/*
366
 * kdb_getphysword
367
 * Inputs:
368
 *	word	Pointer to the word to receive the result.
369
 *	addr	Address of the area to copy.
370
 *	size	Size of the area.
371
 * Returns:
372
 *	0 for success, < 0 for error.
373
 */
374
int kdb_getphysword(unsigned long *word, unsigned long addr, size_t size)
375
{
376
	int diag;
377
	__u8  w1;
378
	__u16 w2;
379
	__u32 w4;
380
	__u64 w8;
381
	*word = 0;	/* Default value if addr or size is invalid */
382

383
	switch (size) {
384
	case 1:
385
		diag = kdb_getphys(&w1, addr, sizeof(w1));
386
		if (!diag)
387
			*word = w1;
388
		break;
389
	case 2:
390
		diag = kdb_getphys(&w2, addr, sizeof(w2));
391
		if (!diag)
392
			*word = w2;
393
		break;
394
	case 4:
395
		diag = kdb_getphys(&w4, addr, sizeof(w4));
396
		if (!diag)
397
			*word = w4;
398
		break;
399
	case 8:
400
		if (size <= sizeof(*word)) {
401
			diag = kdb_getphys(&w8, addr, sizeof(w8));
402
			if (!diag)
403
				*word = w8;
404
			break;
405
		}
406
		fallthrough;
407
	default:
408
		diag = KDB_BADWIDTH;
409
		kdb_func_printf("bad width %zu\n", size);
410
	}
411
	return diag;
412
}
413

414
/*
415
 * kdb_getword - Read a binary value.  Unlike kdb_getarea, this treats
416
 *	data as numbers.
417
 * Inputs:
418
 *	word	Pointer to the word to receive the result.
419
 *	addr	Address of the area to copy.
420
 *	size	Size of the area.
421
 * Returns:
422
 *	0 for success, < 0 for error.
423
 */
424
int kdb_getword(unsigned long *word, unsigned long addr, size_t size)
425
{
426
	int diag;
427
	__u8  w1;
428
	__u16 w2;
429
	__u32 w4;
430
	__u64 w8;
431
	*word = 0;	/* Default value if addr or size is invalid */
432
	switch (size) {
433
	case 1:
434
		diag = kdb_getarea(w1, addr);
435
		if (!diag)
436
			*word = w1;
437
		break;
438
	case 2:
439
		diag = kdb_getarea(w2, addr);
440
		if (!diag)
441
			*word = w2;
442
		break;
443
	case 4:
444
		diag = kdb_getarea(w4, addr);
445
		if (!diag)
446
			*word = w4;
447
		break;
448
	case 8:
449
		if (size <= sizeof(*word)) {
450
			diag = kdb_getarea(w8, addr);
451
			if (!diag)
452
				*word = w8;
453
			break;
454
		}
455
		fallthrough;
456
	default:
457
		diag = KDB_BADWIDTH;
458
		kdb_func_printf("bad width %zu\n", size);
459
	}
460
	return diag;
461
}
462

463
/*
464
 * kdb_putword - Write a binary value.  Unlike kdb_putarea, this
465
 *	treats data as numbers.
466
 * Inputs:
467
 *	addr	Address of the area to write to..
468
 *	word	The value to set.
469
 *	size	Size of the area.
470
 * Returns:
471
 *	0 for success, < 0 for error.
472
 */
473
int kdb_putword(unsigned long addr, unsigned long word, size_t size)
474
{
475
	int diag;
476
	__u8  w1;
477
	__u16 w2;
478
	__u32 w4;
479
	__u64 w8;
480
	switch (size) {
481
	case 1:
482
		w1 = word;
483
		diag = kdb_putarea(addr, w1);
484
		break;
485
	case 2:
486
		w2 = word;
487
		diag = kdb_putarea(addr, w2);
488
		break;
489
	case 4:
490
		w4 = word;
491
		diag = kdb_putarea(addr, w4);
492
		break;
493
	case 8:
494
		if (size <= sizeof(word)) {
495
			w8 = word;
496
			diag = kdb_putarea(addr, w8);
497
			break;
498
		}
499
		fallthrough;
500
	default:
501
		diag = KDB_BADWIDTH;
502
		kdb_func_printf("bad width %zu\n", size);
503
	}
504
	return diag;
505
}
506

507

508

509
/*
510
 * kdb_task_state_char - Return the character that represents the task state.
511
 * Inputs:
512
 *	p	struct task for the process
513
 * Returns:
514
 *	One character to represent the task state.
515
 */
516
char kdb_task_state_char (const struct task_struct *p)
517
{
518
	unsigned long tmp;
519
	char state;
520
	int cpu;
521

522
	if (!p ||
523
	    copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long)))
524
		return 'E';
525

526
	state = task_state_to_char((struct task_struct *) p);
527

528
	if (is_idle_task(p)) {
529
		/* Idle task.  Is it really idle, apart from the kdb
530
		 * interrupt? */
531
		cpu = kdb_process_cpu(p);
532
		if (!kdb_task_has_cpu(p) || kgdb_info[cpu].irq_depth == 1) {
533
			if (cpu != kdb_initial_cpu)
534
				state = '-';	/* idle task */
535
		}
536
	} else if (!p->mm && strchr("IMS", state)) {
537
		state = tolower(state);		/* sleeping system daemon */
538
	}
539
	return state;
540
}
541

542
/*
543
 * kdb_task_state - Return true if a process has the desired state
544
 *	given by the mask.
545
 * Inputs:
546
 *	p	struct task for the process
547
 *	mask	set of characters used to select processes; both NULL
548
 *	        and the empty string mean adopt a default filter, which
549
 *	        is to suppress sleeping system daemons and the idle tasks
550
 * Returns:
551
 *	True if the process matches at least one criteria defined by the mask.
552
 */
553
bool kdb_task_state(const struct task_struct *p, const char *mask)
554
{
555
	char state = kdb_task_state_char(p);
556

557
	/* If there is no mask, then we will filter code that runs when the
558
	 * scheduler is idling and any system daemons that are currently
559
	 * sleeping.
560
	 */
561
	if (!mask || mask[0] == '\0')
562
		return !strchr("-ims", state);
563

564
	/* A is a special case that matches all states */
565
	if (strchr(mask, 'A'))
566
		return true;
567

568
	return strchr(mask, state);
569
}
570

571