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 <xavier.bru@bull.net>
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/ctype.h>
27#include "kdb_private.h"
28
29/*
30 * kdbgetsymval - Return the address of the given symbol.
31 *
32 * Parameters:
33 * symname Character string containing symbol name
34 * symtab Structure to receive results
35 * Returns:
36 * 0 Symbol not found, symtab zero filled
37 * 1 Symbol mapped to module/symbol/section, data in symtab
38 */
39int kdbgetsymval(const char *symname, kdb_symtab_t *symtab)
40{
41 kdb_dbg_printf(AR, "symname=%s, symtab=%px\n", symname, symtab);
42 memset(symtab, 0, sizeof(*symtab));
43 symtab->sym_start = kallsyms_lookup_name(name: symname);
44 if (symtab->sym_start) {
45 kdb_dbg_printf(AR, "returns 1, symtab->sym_start=0x%lx\n",
46 symtab->sym_start);
47 return 1;
48 }
49 kdb_dbg_printf(AR, "returns 0\n");
50 return 0;
51}
52EXPORT_SYMBOL(kdbgetsymval);
53
54/**
55 * kdbnearsym() - Return the name of the symbol with the nearest address
56 * less than @addr.
57 * @addr: Address to check for near symbol
58 * @symtab: Structure to receive results
59 *
60 * WARNING: This function may return a pointer to a single statically
61 * allocated buffer (namebuf). kdb's unusual calling context (single
62 * threaded, all other CPUs halted) provides us sufficient locking for
63 * this to be safe. The only constraint imposed by the static buffer is
64 * that the caller must consume any previous reply prior to another call
65 * to lookup a new symbol.
66 *
67 * Note that, strictly speaking, some architectures may re-enter the kdb
68 * trap if the system turns out to be very badly damaged and this breaks
69 * the single-threaded assumption above. In these circumstances successful
70 * continuation and exit from the inner trap is unlikely to work and any
71 * user attempting this receives a prominent warning before being allowed
72 * to progress. In these circumstances we remain memory safe because
73 * namebuf[KSYM_NAME_LEN-1] will never change from '\0' although we do
74 * tolerate the possibility of garbled symbol display from the outer kdb
75 * trap.
76 *
77 * Return:
78 * * 0 - No sections contain this address, symtab zero filled
79 * * 1 - Address mapped to module/symbol/section, data in symtab
80 */
81int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
82{
83 int ret = 0;
84 unsigned long symbolsize = 0;
85 unsigned long offset = 0;
86 static char namebuf[KSYM_NAME_LEN];
87
88 kdb_dbg_printf(AR, "addr=0x%lx, symtab=%px\n", addr, symtab);
89 memset(symtab, 0, sizeof(*symtab));
90
91 if (addr < 4096)
92 goto out;
93
94 symtab->sym_name = kallsyms_lookup(addr, symbolsize: &symbolsize , offset: &offset,
95 modname: (char **)(&symtab->mod_name), namebuf);
96 if (offset > 8*1024*1024) {
97 symtab->sym_name = NULL;
98 addr = offset = symbolsize = 0;
99 }
100 symtab->sym_start = addr - offset;
101 symtab->sym_end = symtab->sym_start + symbolsize;
102 ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';
103
104 if (symtab->mod_name == NULL)
105 symtab->mod_name = "kernel";
106 kdb_dbg_printf(AR, "returns %d symtab->sym_start=0x%lx, symtab->mod_name=%px, symtab->sym_name=%px (%s)\n",
107 ret, symtab->sym_start, symtab->mod_name, symtab->sym_name, symtab->sym_name);
108out:
109 return ret;
110}
111
112static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];
113
114/*
115 * kallsyms_symbol_complete
116 *
117 * Parameters:
118 * prefix_name prefix of a symbol name to lookup
119 * max_len maximum length that can be returned
120 * Returns:
121 * Number of symbols which match the given prefix.
122 * Notes:
123 * prefix_name is changed to contain the longest unique prefix that
124 * starts with this prefix (tab completion).
125 */
126int kallsyms_symbol_complete(char *prefix_name, int max_len)
127{
128 loff_t pos = 0;
129 int prefix_len = strlen(prefix_name), prev_len = 0;
130 int i, number = 0;
131 const char *name;
132
133 while ((name = kdb_walk_kallsyms(pos: &pos))) {
134 if (strncmp(name, prefix_name, prefix_len) == 0) {
135 strscpy(ks_namebuf, name, sizeof(ks_namebuf));
136 /* Work out the longest name that matches the prefix */
137 if (++number == 1) {
138 prev_len = min_t(int, max_len-1,
139 strlen(ks_namebuf));
140 memcpy(ks_namebuf_prev, ks_namebuf, prev_len);
141 ks_namebuf_prev[prev_len] = '\0';
142 continue;
143 }
144 for (i = 0; i < prev_len; i++) {
145 if (ks_namebuf[i] != ks_namebuf_prev[i]) {
146 prev_len = i;
147 ks_namebuf_prev[i] = '\0';
148 break;
149 }
150 }
151 }
152 }
153 if (prev_len > prefix_len)
154 memcpy(prefix_name, ks_namebuf_prev, prev_len+1);
155 return number;
156}
157
158/*
159 * kallsyms_symbol_next
160 *
161 * Parameters:
162 * prefix_name prefix of a symbol name to lookup
163 * flag 0 means search from the head, 1 means continue search.
164 * buf_size maximum length that can be written to prefix_name
165 * buffer
166 * Returns:
167 * 1 if a symbol matches the given prefix.
168 * 0 if no string found
169 */
170int kallsyms_symbol_next(char *prefix_name, int flag, int buf_size)
171{
172 int prefix_len = strlen(prefix_name);
173 static loff_t pos;
174 const char *name;
175
176 if (!flag)
177 pos = 0;
178
179 while ((name = kdb_walk_kallsyms(pos: &pos))) {
180 if (!strncmp(name, prefix_name, prefix_len))
181 return strscpy(prefix_name, name, buf_size);
182 }
183 return 0;
184}
185
186/*
187 * kdb_symbol_print - Standard method for printing a symbol name and offset.
188 * Inputs:
189 * addr Address to be printed.
190 * symtab Address of symbol data, if NULL this routine does its
191 * own lookup.
192 * punc Punctuation for string, bit field.
193 * Remarks:
194 * The string and its punctuation is only printed if the address
195 * is inside the kernel, except that the value is always printed
196 * when requested.
197 */
198void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p,
199 unsigned int punc)
200{
201 kdb_symtab_t symtab, *symtab_p2;
202 if (symtab_p) {
203 symtab_p2 = (kdb_symtab_t *)symtab_p;
204 } else {
205 symtab_p2 = &symtab;
206 kdbnearsym(addr, symtab: symtab_p2);
207 }
208 if (!(symtab_p2->sym_name || (punc & KDB_SP_VALUE)))
209 return;
210 if (punc & KDB_SP_SPACEB)
211 kdb_printf(" ");
212 if (punc & KDB_SP_VALUE)
213 kdb_printf(kdb_machreg_fmt0, addr);
214 if (symtab_p2->sym_name) {
215 if (punc & KDB_SP_VALUE)
216 kdb_printf(" ");
217 if (punc & KDB_SP_PAREN)
218 kdb_printf("(");
219 if (strcmp(symtab_p2->mod_name, "kernel"))
220 kdb_printf("[%s]", symtab_p2->mod_name);
221 kdb_printf("%s", symtab_p2->sym_name);
222 if (addr != symtab_p2->sym_start)
223 kdb_printf("+0x%lx", addr - symtab_p2->sym_start);
224 if (punc & KDB_SP_SYMSIZE)
225 kdb_printf("/0x%lx",
226 symtab_p2->sym_end - symtab_p2->sym_start);
227 if (punc & KDB_SP_PAREN)
228 kdb_printf(")");
229 }
230 if (punc & KDB_SP_SPACEA)
231 kdb_printf(" ");
232 if (punc & KDB_SP_NEWLINE)
233 kdb_printf("\n");
234}
235
236/*
237 * kdb_strdup - kdb equivalent of strdup, for disasm code.
238 * Inputs:
239 * str The string to duplicate.
240 * type Flags to kmalloc for the new string.
241 * Returns:
242 * Address of the new string, NULL if storage could not be allocated.
243 * Remarks:
244 * This is not in lib/string.c because it uses kmalloc which is not
245 * available when string.o is used in boot loaders.
246 */
247char *kdb_strdup(const char *str, gfp_t type)
248{
249 int n = strlen(str)+1;
250 char *s = kmalloc(size: n, flags: type);
251 if (!s)
252 return NULL;
253 return strcpy(p: s, q: str);
254}
255
256/*
257 * kdb_getarea_size - Read an area of data. The kdb equivalent of
258 * copy_from_user, with kdb messages for invalid addresses.
259 * Inputs:
260 * res Pointer to the area to receive the result.
261 * addr Address of the area to copy.
262 * size Size of the area.
263 * Returns:
264 * 0 for success, < 0 for error.
265 */
266int kdb_getarea_size(void *res, unsigned long addr, size_t size)
267{
268 int ret = copy_from_kernel_nofault(dst: (char *)res, src: (char *)addr, size);
269 if (ret) {
270 if (!KDB_STATE(SUPPRESS)) {
271 kdb_func_printf("Bad address 0x%lx\n", addr);
272 KDB_STATE_SET(SUPPRESS);
273 }
274 ret = KDB_BADADDR;
275 } else {
276 KDB_STATE_CLEAR(SUPPRESS);
277 }
278 return ret;
279}
280
281/*
282 * kdb_putarea_size - Write an area of data. The kdb equivalent of
283 * copy_to_user, with kdb messages for invalid addresses.
284 * Inputs:
285 * addr Address of the area to write to.
286 * res Pointer to the area holding the data.
287 * size Size of the area.
288 * Returns:
289 * 0 for success, < 0 for error.
290 */
291int kdb_putarea_size(unsigned long addr, void *res, size_t size)
292{
293 int ret = copy_to_kernel_nofault(dst: (char *)addr, src: (char *)res, size);
294 if (ret) {
295 if (!KDB_STATE(SUPPRESS)) {
296 kdb_func_printf("Bad address 0x%lx\n", addr);
297 KDB_STATE_SET(SUPPRESS);
298 }
299 ret = KDB_BADADDR;
300 } else {
301 KDB_STATE_CLEAR(SUPPRESS);
302 }
303 return ret;
304}
305
306/*
307 * kdb_getphys - Read data from a physical address. Validate the
308 * address is in range, use kmap_atomic() to get data
309 * similar to kdb_getarea() - but for phys addresses
310 * Inputs:
311 * res Pointer to the word to receive the result
312 * addr Physical address of the area to copy
313 * size Size of the area
314 * Returns:
315 * 0 for success, < 0 for error.
316 */
317static int kdb_getphys(void *res, unsigned long addr, size_t size)
318{
319 unsigned long pfn;
320 void *vaddr;
321 struct page *page;
322
323 pfn = (addr >> PAGE_SHIFT);
324 if (!pfn_valid(pfn))
325 return 1;
326 page = pfn_to_page(pfn);
327 vaddr = kmap_atomic(page);
328 memcpy(res, vaddr + (addr & (PAGE_SIZE - 1)), size);
329 kunmap_atomic(vaddr);
330
331 return 0;
332}
333
334/*
335 * kdb_getphysword
336 * Inputs:
337 * word Pointer to the word to receive the result.
338 * addr Address of the area to copy.
339 * size Size of the area.
340 * Returns:
341 * 0 for success, < 0 for error.
342 */
343int kdb_getphysword(unsigned long *word, unsigned long addr, size_t size)
344{
345 int diag;
346 __u8 w1;
347 __u16 w2;
348 __u32 w4;
349 __u64 w8;
350 *word = 0; /* Default value if addr or size is invalid */
351
352 switch (size) {
353 case 1:
354 diag = kdb_getphys(res: &w1, addr, size: sizeof(w1));
355 if (!diag)
356 *word = w1;
357 break;
358 case 2:
359 diag = kdb_getphys(res: &w2, addr, size: sizeof(w2));
360 if (!diag)
361 *word = w2;
362 break;
363 case 4:
364 diag = kdb_getphys(res: &w4, addr, size: sizeof(w4));
365 if (!diag)
366 *word = w4;
367 break;
368 case 8:
369 if (size <= sizeof(*word)) {
370 diag = kdb_getphys(res: &w8, addr, size: sizeof(w8));
371 if (!diag)
372 *word = w8;
373 break;
374 }
375 fallthrough;
376 default:
377 diag = KDB_BADWIDTH;
378 kdb_func_printf("bad width %zu\n", size);
379 }
380 return diag;
381}
382
383/*
384 * kdb_getword - Read a binary value. Unlike kdb_getarea, this treats
385 * data as numbers.
386 * Inputs:
387 * word Pointer to the word to receive the result.
388 * addr Address of the area to copy.
389 * size Size of the area.
390 * Returns:
391 * 0 for success, < 0 for error.
392 */
393int kdb_getword(unsigned long *word, unsigned long addr, size_t size)
394{
395 int diag;
396 __u8 w1;
397 __u16 w2;
398 __u32 w4;
399 __u64 w8;
400 *word = 0; /* Default value if addr or size is invalid */
401 switch (size) {
402 case 1:
403 diag = kdb_getarea(w1, addr);
404 if (!diag)
405 *word = w1;
406 break;
407 case 2:
408 diag = kdb_getarea(w2, addr);
409 if (!diag)
410 *word = w2;
411 break;
412 case 4:
413 diag = kdb_getarea(w4, addr);
414 if (!diag)
415 *word = w4;
416 break;
417 case 8:
418 if (size <= sizeof(*word)) {
419 diag = kdb_getarea(w8, addr);
420 if (!diag)
421 *word = w8;
422 break;
423 }
424 fallthrough;
425 default:
426 diag = KDB_BADWIDTH;
427 kdb_func_printf("bad width %zu\n", size);
428 }
429 return diag;
430}
431
432/*
433 * kdb_putword - Write a binary value. Unlike kdb_putarea, this
434 * treats data as numbers.
435 * Inputs:
436 * addr Address of the area to write to..
437 * word The value to set.
438 * size Size of the area.
439 * Returns:
440 * 0 for success, < 0 for error.
441 */
442int kdb_putword(unsigned long addr, unsigned long word, size_t size)
443{
444 int diag;
445 __u8 w1;
446 __u16 w2;
447 __u32 w4;
448 __u64 w8;
449 switch (size) {
450 case 1:
451 w1 = word;
452 diag = kdb_putarea(addr, w1);
453 break;
454 case 2:
455 w2 = word;
456 diag = kdb_putarea(addr, w2);
457 break;
458 case 4:
459 w4 = word;
460 diag = kdb_putarea(addr, w4);
461 break;
462 case 8:
463 if (size <= sizeof(word)) {
464 w8 = word;
465 diag = kdb_putarea(addr, w8);
466 break;
467 }
468 fallthrough;
469 default:
470 diag = KDB_BADWIDTH;
471 kdb_func_printf("bad width %zu\n", size);
472 }
473 return diag;
474}
475
476
477
478/*
479 * kdb_task_state_char - Return the character that represents the task state.
480 * Inputs:
481 * p struct task for the process
482 * Returns:
483 * One character to represent the task state.
484 */
485char kdb_task_state_char (const struct task_struct *p)
486{
487 unsigned long tmp;
488 char state;
489 int cpu;
490
491 if (!p ||
492 copy_from_kernel_nofault(dst: &tmp, src: (char *)p, size: sizeof(unsigned long)))
493 return 'E';
494
495 state = task_state_to_char(tsk: (struct task_struct *) p);
496
497 if (is_idle_task(p)) {
498 /* Idle task. Is it really idle, apart from the kdb
499 * interrupt? */
500 cpu = kdb_process_cpu(p);
501 if (!kdb_task_has_cpu(p) || kgdb_info[cpu].irq_depth == 1) {
502 if (cpu != kdb_initial_cpu)
503 state = '-'; /* idle task */
504 }
505 } else if (!p->mm && strchr("IMS", state)) {
506 state = tolower(state); /* sleeping system daemon */
507 }
508 return state;
509}
510
511/*
512 * kdb_task_state - Return true if a process has the desired state
513 * given by the mask.
514 * Inputs:
515 * p struct task for the process
516 * mask set of characters used to select processes; both NULL
517 * and the empty string mean adopt a default filter, which
518 * is to suppress sleeping system daemons and the idle tasks
519 * Returns:
520 * True if the process matches at least one criteria defined by the mask.
521 */
522bool kdb_task_state(const struct task_struct *p, const char *mask)
523{
524 char state = kdb_task_state_char(p);
525
526 /* If there is no mask, then we will filter code that runs when the
527 * scheduler is idling and any system daemons that are currently
528 * sleeping.
529 */
530 if (!mask || mask[0] == '\0')
531 return !strchr("-ims", state);
532
533 /* A is a special case that matches all states */
534 if (strchr(mask, 'A'))
535 return true;
536
537 return strchr(mask, state);
538}
539
540/* Maintain a small stack of kdb_flags to allow recursion without disturbing
541 * the global kdb state.
542 */
543
544static int kdb_flags_stack[4], kdb_flags_index;
545
546void kdb_save_flags(void)
547{
548 BUG_ON(kdb_flags_index >= ARRAY_SIZE(kdb_flags_stack));
549 kdb_flags_stack[kdb_flags_index++] = kdb_flags;
550}
551
552void kdb_restore_flags(void)
553{
554 BUG_ON(kdb_flags_index <= 0);
555 kdb_flags = kdb_flags_stack[--kdb_flags_index];
556}
557

source code of linux/kernel/debug/kdb/kdb_support.c