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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Kernel Debugger Architecture Independent Support Functions
4 *
5 * Copyright (c) 1999-2004 Silicon Graphics, Inc. All Rights Reserved.
6 * Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved.
7 * 03/02/13 added new 2.5 kallsyms <[email protected]>
8 */
9
10#include <linux/types.h>
11#include <linux/sched.h>
12#include <linux/mm.h>
13#include <linux/kallsyms.h>
14#include <linux/stddef.h>
15#include <linux/vmalloc.h>
16#include <linux/ptrace.h>
17#include <linux/highmem.h>
18#include <linux/hardirq.h>
19#include <linux/delay.h>
20#include <linux/uaccess.h>
21#include <linux/kdb.h>
22#include <linux/slab.h>
23#include <linux/string.h>
24#include <linux/ctype.h>
25#include "kdb_private.h"
26
27/*
28 * kdbgetsymval - Return the address of the given symbol.
29 *
30 * Parameters:
31 * symname Character string containing symbol name
32 * symtab Structure to receive results
33 * Returns:
34 * 0 Symbol not found, symtab zero filled
35 * 1 Symbol mapped to module/symbol/section, data in symtab
36 */
37int kdbgetsymval(const char *symname, kdb_symtab_t *symtab)
38{
39 kdb_dbg_printf(AR, "symname=%s, symtab=%px\n", symname, symtab);
40 memset(symtab, 0, sizeof(*symtab));
41 symtab->sym_start = kallsyms_lookup_name(symname);
42 if (symtab->sym_start) {
43 kdb_dbg_printf(AR, "returns 1, symtab->sym_start=0x%lx\n",
44 symtab->sym_start);
45 return 1;
46 }
47 kdb_dbg_printf(AR, "returns 0\n");
48 return 0;
49}
50EXPORT_SYMBOL(kdbgetsymval);
51
52/**
53 * kdbnearsym() - Return the name of the symbol with the nearest address
54 * less than @addr.
55 * @addr: Address to check for near symbol
56 * @symtab: Structure to receive results
57 *
58 * WARNING: This function may return a pointer to a single statically
59 * allocated buffer (namebuf). kdb's unusual calling context (single
60 * threaded, all other CPUs halted) provides us sufficient locking for
61 * this to be safe. The only constraint imposed by the static buffer is
62 * that the caller must consume any previous reply prior to another call
63 * to lookup a new symbol.
64 *
65 * Note that, strictly speaking, some architectures may re-enter the kdb
66 * trap if the system turns out to be very badly damaged and this breaks
67 * the single-threaded assumption above. In these circumstances successful
68 * continuation and exit from the inner trap is unlikely to work and any
69 * user attempting this receives a prominent warning before being allowed
70 * to progress. In these circumstances we remain memory safe because
71 * namebuf[KSYM_NAME_LEN-1] will never change from '\0' although we do
72 * tolerate the possibility of garbled symbol display from the outer kdb
73 * trap.
74 *
75 * Return:
76 * * 0 - No sections contain this address, symtab zero filled
77 * * 1 - Address mapped to module/symbol/section, data in symtab
78 */
79int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
80{
81 int ret = 0;
82 unsigned long symbolsize = 0;
83 unsigned long offset = 0;
84 static char namebuf[KSYM_NAME_LEN];
85
86 kdb_dbg_printf(AR, "addr=0x%lx, symtab=%px\n", addr, symtab);
87 memset(symtab, 0, sizeof(*symtab));
88
89 if (addr < 4096)
90 goto out;
91
92 symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
93 (char **)(&symtab->mod_name), namebuf);
94 if (offset > 8*1024*1024) {
95 symtab->sym_name = NULL;
96 addr = offset = symbolsize = 0;
97 }
98 symtab->sym_start = addr - offset;
99 symtab->sym_end = symtab->sym_start + symbolsize;
100 ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';
101
102 if (symtab->mod_name == NULL)
103 symtab->mod_name = "kernel";
104 kdb_dbg_printf(AR, "returns %d symtab->sym_start=0x%lx, symtab->mod_name=%px, symtab->sym_name=%px (%s)\n",
105 ret, symtab->sym_start, symtab->mod_name, symtab->sym_name, symtab->sym_name);
106out:
107 return ret;
108}
109
110static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];
111
112/*
113 * kallsyms_symbol_complete
114 *
115 * Parameters:
116 * prefix_name prefix of a symbol name to lookup
117 * max_len maximum length that can be returned
118 * Returns:
119 * Number of symbols which match the given prefix.
120 * Notes:
121 * prefix_name is changed to contain the longest unique prefix that
122 * starts with this prefix (tab completion).
123 */
124int kallsyms_symbol_complete(char *prefix_name, int max_len)
125{
126 loff_t pos = 0;
127 int prefix_len = strlen(prefix_name), prev_len = 0;
128 int i, number = 0;
129 const char *name;
130
131 while ((name = kdb_walk_kallsyms(&pos))) {
132 if (strncmp(name, prefix_name, prefix_len) == 0) {
133 strscpy(ks_namebuf, name, sizeof(ks_namebuf));
134 /* Work out the longest name that matches the prefix */
135 if (++number == 1) {
136 prev_len = min_t(int, max_len-1,
137 strlen(ks_namebuf));
138 memcpy(ks_namebuf_prev, ks_namebuf, prev_len);
139 ks_namebuf_prev[prev_len] = '\0';
140 continue;
141 }
142 for (i = 0; i < prev_len; i++) {
143 if (ks_namebuf[i] != ks_namebuf_prev[i]) {
144 prev_len = i;
145 ks_namebuf_prev[i] = '\0';
146 break;
147 }
148 }
149 }
150 }
151 if (prev_len > prefix_len)
152 memcpy(prefix_name, ks_namebuf_prev, prev_len+1);
153 return number;
154}
155
156/*
157 * kallsyms_symbol_next
158 *
159 * Parameters:
160 * prefix_name prefix of a symbol name to lookup
161 * flag 0 means search from the head, 1 means continue search.
162 * buf_size maximum length that can be written to prefix_name
163 * buffer
164 * Returns:
165 * 1 if a symbol matches the given prefix.
166 * 0 if no string found
167 */
168int kallsyms_symbol_next(char *prefix_name, int flag, int buf_size)
169{
170 int prefix_len = strlen(prefix_name);
171 static loff_t pos;
172 const char *name;
173
174 if (!flag)
175 pos = 0;
176
177 while ((name = kdb_walk_kallsyms(&pos))) {
178 if (!strncmp(name, prefix_name, prefix_len))
179 return strscpy(prefix_name, name, buf_size);
180 }
181 return 0;
182}
183
184/*
185 * kdb_symbol_print - Standard method for printing a symbol name and offset.
186 * Inputs:
187 * addr Address to be printed.
188 * symtab Address of symbol data, if NULL this routine does its
189 * own lookup.
190 * punc Punctuation for string, bit field.
191 * Remarks:
192 * The string and its punctuation is only printed if the address
193 * is inside the kernel, except that the value is always printed
194 * when requested.
195 */
196void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p,
197 unsigned int punc)
198{
199 kdb_symtab_t symtab, *symtab_p2;
200 if (symtab_p) {
201 symtab_p2 = (kdb_symtab_t *)symtab_p;
202 } else {
203 symtab_p2 = &symtab;
204 kdbnearsym(addr, symtab_p2);
205 }
206 if (!(symtab_p2->sym_name || (punc & KDB_SP_VALUE)))
207 return;
208 if (punc & KDB_SP_SPACEB)
209 kdb_printf(" ");
210 if (punc & KDB_SP_VALUE)
211 kdb_printf(kdb_machreg_fmt0, addr);
212 if (symtab_p2->sym_name) {
213 if (punc & KDB_SP_VALUE)
214 kdb_printf(" ");
215 if (punc & KDB_SP_PAREN)
216 kdb_printf("(");
217 if (strcmp(symtab_p2->mod_name, "kernel"))
218 kdb_printf("[%s]", symtab_p2->mod_name);
219 kdb_printf("%s", symtab_p2->sym_name);
220 if (addr != symtab_p2->sym_start)
221 kdb_printf("+0x%lx", addr - symtab_p2->sym_start);
222 if (punc & KDB_SP_SYMSIZE)
223 kdb_printf("/0x%lx",
224 symtab_p2->sym_end - symtab_p2->sym_start);
225 if (punc & KDB_SP_PAREN)
226 kdb_printf(")");
227 }
228 if (punc & KDB_SP_SPACEA)
229 kdb_printf(" ");
230 if (punc & KDB_SP_NEWLINE)
231 kdb_printf("\n");
232}
233
234/*
235 * kdb_strdup - kdb equivalent of strdup, for disasm code.
236 * Inputs:
237 * str The string to duplicate.
238 * type Flags to kmalloc for the new string.
239 * Returns:
240 * Address of the new string, NULL if storage could not be allocated.
241 * Remarks:
242 * This is not in lib/string.c because it uses kmalloc which is not
243 * available when string.o is used in boot loaders.
244 */
245char *kdb_strdup(const char *str, gfp_t type)
246{
247 size_t n = strlen(str) + 1;
248 char *s = kmalloc(n, type);
249 if (!s)
250 return NULL;
251 memcpy(s, str, n);
252 return s;
253}
254
255/*
256 * kdb_strdup_dequote - same as kdb_strdup(), but trims surrounding quotes from
257 * the input string if present.
258 * Remarks:
259 * Quotes are only removed if there is both a leading and a trailing quote.
260 */
261char *kdb_strdup_dequote(const char *str, gfp_t type)
262{
263 size_t len = strlen(str);
264 char *s;
265
266 if (str[0] == '"' && len > 1 && str[len - 1] == '"') {
267 /* trim both leading and trailing quotes */
268 str++;
269 len -= 2;
270 }
271
272 len++; /* add space for NUL terminator */
273
274 s = kmalloc(len, type);
275 if (!s)
276 return NULL;
277
278 memcpy(s, str, len - 1);
279 s[len - 1] = '\0';
280
281 return s;
282}
283
284/*
285 * kdb_getarea_size - Read an area of data. The kdb equivalent of
286 * copy_from_user, with kdb messages for invalid addresses.
287 * Inputs:
288 * res Pointer to the area to receive the result.
289 * addr Address of the area to copy.
290 * size Size of the area.
291 * Returns:
292 * 0 for success, < 0 for error.
293 */
294int kdb_getarea_size(void *res, unsigned long addr, size_t size)
295{
296 int ret = copy_from_kernel_nofault((char *)res, (char *)addr, size);
297 if (ret) {
298 if (!KDB_STATE(SUPPRESS)) {
299 kdb_func_printf("Bad address 0x%lx\n", addr);
300 KDB_STATE_SET(SUPPRESS);
301 }
302 ret = KDB_BADADDR;
303 } else {
304 KDB_STATE_CLEAR(SUPPRESS);
305 }
306 return ret;
307}
308
309/*
310 * kdb_putarea_size - Write an area of data. The kdb equivalent of
311 * copy_to_user, with kdb messages for invalid addresses.
312 * Inputs:
313 * addr Address of the area to write to.
314 * res Pointer to the area holding the data.
315 * size Size of the area.
316 * Returns:
317 * 0 for success, < 0 for error.
318 */
319int kdb_putarea_size(unsigned long addr, void *res, size_t size)
320{
321 int ret = copy_to_kernel_nofault((char *)addr, (char *)res, size);
322 if (ret) {
323 if (!KDB_STATE(SUPPRESS)) {
324 kdb_func_printf("Bad address 0x%lx\n", addr);
325 KDB_STATE_SET(SUPPRESS);
326 }
327 ret = KDB_BADADDR;
328 } else {
329 KDB_STATE_CLEAR(SUPPRESS);
330 }
331 return ret;
332}
333
334/*
335 * kdb_getphys - Read data from a physical address. Validate the
336 * address is in range, use kmap_local_page() to get data
337 * similar to kdb_getarea() - but for phys addresses
338 * Inputs:
339 * res Pointer to the word to receive the result
340 * addr Physical address of the area to copy
341 * size Size of the area
342 * Returns:
343 * 0 for success, < 0 for error.
344 */
345static int kdb_getphys(void *res, unsigned long addr, size_t size)
346{
347 unsigned long pfn;
348 void *vaddr;
349 struct page *page;
350
351 pfn = (addr >> PAGE_SHIFT);
352 if (!pfn_valid(pfn))
353 return 1;
354 page = pfn_to_page(pfn);
355 vaddr = kmap_local_page(page);
356 memcpy(res, vaddr + (addr & (PAGE_SIZE - 1)), size);
357 kunmap_local(vaddr);
358
359 return 0;
360}
361
362/*
363 * kdb_getphysword
364 * Inputs:
365 * word Pointer to the word to receive the result.
366 * addr Address of the area to copy.
367 * size Size of the area.
368 * Returns:
369 * 0 for success, < 0 for error.
370 */
371int kdb_getphysword(unsigned long *word, unsigned long addr, size_t size)
372{
373 int diag;
374 __u8 w1;
375 __u16 w2;
376 __u32 w4;
377 __u64 w8;
378 *word = 0; /* Default value if addr or size is invalid */
379
380 switch (size) {
381 case 1:
382 diag = kdb_getphys(&w1, addr, sizeof(w1));
383 if (!diag)
384 *word = w1;
385 break;
386 case 2:
387 diag = kdb_getphys(&w2, addr, sizeof(w2));
388 if (!diag)
389 *word = w2;
390 break;
391 case 4:
392 diag = kdb_getphys(&w4, addr, sizeof(w4));
393 if (!diag)
394 *word = w4;
395 break;
396 case 8:
397 if (size <= sizeof(*word)) {
398 diag = kdb_getphys(&w8, addr, sizeof(w8));
399 if (!diag)
400 *word = w8;
401 break;
402 }
403 fallthrough;
404 default:
405 diag = KDB_BADWIDTH;
406 kdb_func_printf("bad width %zu\n", size);
407 }
408 return diag;
409}
410
411/*
412 * kdb_getword - Read a binary value. Unlike kdb_getarea, this treats
413 * data as numbers.
414 * Inputs:
415 * word Pointer to the word to receive the result.
416 * addr Address of the area to copy.
417 * size Size of the area.
418 * Returns:
419 * 0 for success, < 0 for error.
420 */
421int kdb_getword(unsigned long *word, unsigned long addr, size_t size)
422{
423 int diag;
424 __u8 w1;
425 __u16 w2;
426 __u32 w4;
427 __u64 w8;
428 *word = 0; /* Default value if addr or size is invalid */
429 switch (size) {
430 case 1:
431 diag = kdb_getarea(w1, addr);
432 if (!diag)
433 *word = w1;
434 break;
435 case 2:
436 diag = kdb_getarea(w2, addr);
437 if (!diag)
438 *word = w2;
439 break;
440 case 4:
441 diag = kdb_getarea(w4, addr);
442 if (!diag)
443 *word = w4;
444 break;
445 case 8:
446 if (size <= sizeof(*word)) {
447 diag = kdb_getarea(w8, addr);
448 if (!diag)
449 *word = w8;
450 break;
451 }
452 fallthrough;
453 default:
454 diag = KDB_BADWIDTH;
455 kdb_func_printf("bad width %zu\n", size);
456 }
457 return diag;
458}
459
460/*
461 * kdb_putword - Write a binary value. Unlike kdb_putarea, this
462 * treats data as numbers.
463 * Inputs:
464 * addr Address of the area to write to..
465 * word The value to set.
466 * size Size of the area.
467 * Returns:
468 * 0 for success, < 0 for error.
469 */
470int kdb_putword(unsigned long addr, unsigned long word, size_t size)
471{
472 int diag;
473 __u8 w1;
474 __u16 w2;
475 __u32 w4;
476 __u64 w8;
477 switch (size) {
478 case 1:
479 w1 = word;
480 diag = kdb_putarea(addr, w1);
481 break;
482 case 2:
483 w2 = word;
484 diag = kdb_putarea(addr, w2);
485 break;
486 case 4:
487 w4 = word;
488 diag = kdb_putarea(addr, w4);
489 break;
490 case 8:
491 if (size <= sizeof(word)) {
492 w8 = word;
493 diag = kdb_putarea(addr, w8);
494 break;
495 }
496 fallthrough;
497 default:
498 diag = KDB_BADWIDTH;
499 kdb_func_printf("bad width %zu\n", size);
500 }
501 return diag;
502}
503
504
505
506/*
507 * kdb_task_state_char - Return the character that represents the task state.
508 * Inputs:
509 * p struct task for the process
510 * Returns:
511 * One character to represent the task state.
512 */
513char kdb_task_state_char (const struct task_struct *p)
514{
515 unsigned long tmp;
516 char state;
517 int cpu;
518
519 if (!p ||
520 copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long)))
521 return 'E';
522
523 state = task_state_to_char((struct task_struct *) p);
524
525 if (is_idle_task(p)) {
526 /* Idle task. Is it really idle, apart from the kdb
527 * interrupt? */
528 cpu = kdb_process_cpu(p);
529 if (!kdb_task_has_cpu(p) || kgdb_info[cpu].irq_depth == 1) {
530 if (cpu != kdb_initial_cpu)
531 state = '-'; /* idle task */
532 }
533 } else if (!p->mm && strchr("IMS", state)) {
534 state = tolower(state); /* sleeping system daemon */
535 }
536 return state;
537}
538
539/*
540 * kdb_task_state - Return true if a process has the desired state
541 * given by the mask.
542 * Inputs:
543 * p struct task for the process
544 * mask set of characters used to select processes; both NULL
545 * and the empty string mean adopt a default filter, which
546 * is to suppress sleeping system daemons and the idle tasks
547 * Returns:
548 * True if the process matches at least one criteria defined by the mask.
549 */
550bool kdb_task_state(const struct task_struct *p, const char *mask)
551{
552 char state = kdb_task_state_char(p);
553
554 /* If there is no mask, then we will filter code that runs when the
555 * scheduler is idling and any system daemons that are currently
556 * sleeping.
557 */
558 if (!mask || mask[0] == '\0')
559 return !strchr("-ims", state);
560
561 /* A is a special case that matches all states */
562 if (strchr(mask, 'A'))
563 return true;
564
565 return strchr(mask, state);
566}