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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Kernel unwinding support | |
3 | * | |
4 | * (c) 2002-2004 Randolph Chung <tausq@debian.org> | |
5 | * | |
6 | * Derived partially from the IA64 implementation. The PA-RISC | |
7 | * Runtime Architecture Document is also a useful reference to | |
8 | * understand what is happening here | |
9 | */ | |
10 | ||
1da177e4 LT |
11 | #include <linux/kernel.h> |
12 | #include <linux/init.h> | |
e6fc0449 | 13 | #include <linux/sched.h> |
1da177e4 LT |
14 | #include <linux/slab.h> |
15 | #include <linux/kallsyms.h> | |
8f78df87 | 16 | #include <linux/sort.h> |
1da177e4 LT |
17 | |
18 | #include <asm/uaccess.h> | |
19 | #include <asm/assembly.h> | |
05dc16d6 RC |
20 | #include <asm/asm-offsets.h> |
21 | #include <asm/ptrace.h> | |
1da177e4 LT |
22 | |
23 | #include <asm/unwind.h> | |
24 | ||
25 | /* #define DEBUG 1 */ | |
26 | #ifdef DEBUG | |
27 | #define dbg(x...) printk(x) | |
28 | #else | |
29 | #define dbg(x...) | |
30 | #endif | |
31 | ||
33a932d1 | 32 | #define KERNEL_START (KERNEL_BINARY_TEXT_START) |
e036306a | 33 | |
1da177e4 LT |
34 | extern struct unwind_table_entry __start___unwind[]; |
35 | extern struct unwind_table_entry __stop___unwind[]; | |
36 | ||
37 | static spinlock_t unwind_lock; | |
38 | /* | |
39 | * the kernel unwind block is not dynamically allocated so that | |
40 | * we can call unwind_init as early in the bootup process as | |
41 | * possible (before the slab allocator is initialized) | |
42 | */ | |
8039de10 | 43 | static struct unwind_table kernel_unwind_table __read_mostly; |
1da177e4 LT |
44 | static LIST_HEAD(unwind_tables); |
45 | ||
46 | static inline const struct unwind_table_entry * | |
47 | find_unwind_entry_in_table(const struct unwind_table *table, unsigned long addr) | |
48 | { | |
49 | const struct unwind_table_entry *e = NULL; | |
50 | unsigned long lo, hi, mid; | |
51 | ||
52 | lo = 0; | |
53 | hi = table->length - 1; | |
54 | ||
55 | while (lo <= hi) { | |
56 | mid = (hi - lo) / 2 + lo; | |
57 | e = &table->table[mid]; | |
58 | if (addr < e->region_start) | |
59 | hi = mid - 1; | |
60 | else if (addr > e->region_end) | |
61 | lo = mid + 1; | |
62 | else | |
63 | return e; | |
64 | } | |
65 | ||
66 | return NULL; | |
67 | } | |
68 | ||
69 | static const struct unwind_table_entry * | |
70 | find_unwind_entry(unsigned long addr) | |
71 | { | |
72 | struct unwind_table *table; | |
73 | const struct unwind_table_entry *e = NULL; | |
74 | ||
75 | if (addr >= kernel_unwind_table.start && | |
76 | addr <= kernel_unwind_table.end) | |
77 | e = find_unwind_entry_in_table(&kernel_unwind_table, addr); | |
be24a897 MP |
78 | else { |
79 | unsigned long flags; | |
80 | ||
81 | spin_lock_irqsave(&unwind_lock, flags); | |
1da177e4 LT |
82 | list_for_each_entry(table, &unwind_tables, list) { |
83 | if (addr >= table->start && | |
84 | addr <= table->end) | |
85 | e = find_unwind_entry_in_table(table, addr); | |
b1b1d4a6 PC |
86 | if (e) { |
87 | /* Move-to-front to exploit common traces */ | |
88 | list_move(&table->list, &unwind_tables); | |
1da177e4 | 89 | break; |
b1b1d4a6 | 90 | } |
1da177e4 | 91 | } |
be24a897 MP |
92 | spin_unlock_irqrestore(&unwind_lock, flags); |
93 | } | |
1da177e4 LT |
94 | |
95 | return e; | |
96 | } | |
97 | ||
98 | static void | |
99 | unwind_table_init(struct unwind_table *table, const char *name, | |
100 | unsigned long base_addr, unsigned long gp, | |
101 | void *table_start, void *table_end) | |
102 | { | |
103 | struct unwind_table_entry *start = table_start; | |
104 | struct unwind_table_entry *end = | |
105 | (struct unwind_table_entry *)table_end - 1; | |
106 | ||
107 | table->name = name; | |
108 | table->base_addr = base_addr; | |
109 | table->gp = gp; | |
110 | table->start = base_addr + start->region_start; | |
111 | table->end = base_addr + end->region_end; | |
112 | table->table = (struct unwind_table_entry *)table_start; | |
113 | table->length = end - start + 1; | |
114 | INIT_LIST_HEAD(&table->list); | |
115 | ||
116 | for (; start <= end; start++) { | |
117 | if (start < end && | |
118 | start->region_end > (start+1)->region_start) { | |
119 | printk("WARNING: Out of order unwind entry! %p and %p\n", start, start+1); | |
120 | } | |
121 | ||
122 | start->region_start += base_addr; | |
123 | start->region_end += base_addr; | |
124 | } | |
125 | } | |
126 | ||
8f78df87 HD |
127 | static int cmp_unwind_table_entry(const void *a, const void *b) |
128 | { | |
129 | return ((const struct unwind_table_entry *)a)->region_start | |
130 | - ((const struct unwind_table_entry *)b)->region_start; | |
131 | } | |
132 | ||
1da177e4 LT |
133 | static void |
134 | unwind_table_sort(struct unwind_table_entry *start, | |
135 | struct unwind_table_entry *finish) | |
136 | { | |
8f78df87 HD |
137 | sort(start, finish - start, sizeof(struct unwind_table_entry), |
138 | cmp_unwind_table_entry, NULL); | |
1da177e4 LT |
139 | } |
140 | ||
141 | struct unwind_table * | |
142 | unwind_table_add(const char *name, unsigned long base_addr, | |
143 | unsigned long gp, | |
144 | void *start, void *end) | |
145 | { | |
146 | struct unwind_table *table; | |
147 | unsigned long flags; | |
148 | struct unwind_table_entry *s = (struct unwind_table_entry *)start; | |
149 | struct unwind_table_entry *e = (struct unwind_table_entry *)end; | |
150 | ||
151 | unwind_table_sort(s, e); | |
152 | ||
153 | table = kmalloc(sizeof(struct unwind_table), GFP_USER); | |
154 | if (table == NULL) | |
155 | return NULL; | |
156 | unwind_table_init(table, name, base_addr, gp, start, end); | |
157 | spin_lock_irqsave(&unwind_lock, flags); | |
158 | list_add_tail(&table->list, &unwind_tables); | |
159 | spin_unlock_irqrestore(&unwind_lock, flags); | |
160 | ||
161 | return table; | |
162 | } | |
163 | ||
164 | void unwind_table_remove(struct unwind_table *table) | |
165 | { | |
166 | unsigned long flags; | |
167 | ||
168 | spin_lock_irqsave(&unwind_lock, flags); | |
169 | list_del(&table->list); | |
170 | spin_unlock_irqrestore(&unwind_lock, flags); | |
171 | ||
172 | kfree(table); | |
173 | } | |
174 | ||
175 | /* Called from setup_arch to import the kernel unwind info */ | |
c790b41b | 176 | int __init unwind_init(void) |
1da177e4 LT |
177 | { |
178 | long start, stop; | |
179 | register unsigned long gp __asm__ ("r27"); | |
180 | ||
181 | start = (long)&__start___unwind[0]; | |
182 | stop = (long)&__stop___unwind[0]; | |
183 | ||
184 | spin_lock_init(&unwind_lock); | |
185 | ||
186 | printk("unwind_init: start = 0x%lx, end = 0x%lx, entries = %lu\n", | |
187 | start, stop, | |
188 | (stop - start) / sizeof(struct unwind_table_entry)); | |
189 | ||
190 | unwind_table_init(&kernel_unwind_table, "kernel", KERNEL_START, | |
191 | gp, | |
192 | &__start___unwind[0], &__stop___unwind[0]); | |
193 | #if 0 | |
194 | { | |
195 | int i; | |
196 | for (i = 0; i < 10; i++) | |
197 | { | |
198 | printk("region 0x%x-0x%x\n", | |
199 | __start___unwind[i].region_start, | |
200 | __start___unwind[i].region_end); | |
201 | } | |
202 | } | |
203 | #endif | |
204 | return 0; | |
205 | } | |
206 | ||
05dc16d6 RC |
207 | #ifdef CONFIG_64BIT |
208 | #define get_func_addr(fptr) fptr[2] | |
209 | #else | |
210 | #define get_func_addr(fptr) fptr[0] | |
211 | #endif | |
212 | ||
213 | static int unwind_special(struct unwind_frame_info *info, unsigned long pc, int frame_size) | |
214 | { | |
78199943 KM |
215 | extern void handle_interruption(int, struct pt_regs *); |
216 | static unsigned long *hi = (unsigned long *)&handle_interruption; | |
05dc16d6 RC |
217 | |
218 | if (pc == get_func_addr(hi)) { | |
219 | struct pt_regs *regs = (struct pt_regs *)(info->sp - frame_size - PT_SZ_ALGN); | |
220 | dbg("Unwinding through handle_interruption()\n"); | |
221 | info->prev_sp = regs->gr[30]; | |
222 | info->prev_ip = regs->iaoq[0]; | |
223 | ||
224 | return 1; | |
225 | } | |
226 | ||
227 | return 0; | |
228 | } | |
229 | ||
1da177e4 LT |
230 | static void unwind_frame_regs(struct unwind_frame_info *info) |
231 | { | |
232 | const struct unwind_table_entry *e; | |
233 | unsigned long npc; | |
234 | unsigned int insn; | |
235 | long frame_size = 0; | |
236 | int looking_for_rp, rpoffset = 0; | |
237 | ||
238 | e = find_unwind_entry(info->ip); | |
239 | if (e == NULL) { | |
240 | unsigned long sp; | |
1da177e4 LT |
241 | |
242 | dbg("Cannot find unwind entry for 0x%lx; forced unwinding\n", info->ip); | |
243 | ||
244 | #ifdef CONFIG_KALLSYMS | |
245 | /* Handle some frequent special cases.... */ | |
246 | { | |
9281acea | 247 | char symname[KSYM_NAME_LEN]; |
cb957795 | 248 | char *modname; |
1da177e4 | 249 | |
cb957795 KM |
250 | kallsyms_lookup(info->ip, NULL, NULL, &modname, |
251 | symname); | |
1da177e4 LT |
252 | |
253 | dbg("info->ip = 0x%lx, name = %s\n", info->ip, symname); | |
254 | ||
255 | if (strcmp(symname, "_switch_to_ret") == 0) { | |
256 | info->prev_sp = info->sp - CALLEE_SAVE_FRAME_SIZE; | |
257 | info->prev_ip = *(unsigned long *)(info->prev_sp - RP_OFFSET); | |
258 | dbg("_switch_to_ret @ %lx - setting " | |
259 | "prev_sp=%lx prev_ip=%lx\n", | |
260 | info->ip, info->prev_sp, | |
261 | info->prev_ip); | |
262 | return; | |
263 | } else if (strcmp(symname, "ret_from_kernel_thread") == 0 || | |
264 | strcmp(symname, "syscall_exit") == 0) { | |
265 | info->prev_ip = info->prev_sp = 0; | |
266 | return; | |
267 | } | |
268 | } | |
269 | #endif | |
270 | ||
271 | /* Since we are doing the unwinding blind, we don't know if | |
272 | we are adjusting the stack correctly or extracting the rp | |
273 | correctly. The rp is checked to see if it belongs to the | |
274 | kernel text section, if not we assume we don't have a | |
275 | correct stack frame and we continue to unwind the stack. | |
276 | This is not quite correct, and will fail for loadable | |
277 | modules. */ | |
278 | sp = info->sp & ~63; | |
279 | do { | |
280 | unsigned long tmp; | |
281 | ||
282 | info->prev_sp = sp - 64; | |
283 | info->prev_ip = 0; | |
284 | if (get_user(tmp, (unsigned long *)(info->prev_sp - RP_OFFSET))) | |
285 | break; | |
286 | info->prev_ip = tmp; | |
287 | sp = info->prev_sp; | |
c790b41b | 288 | } while (!kernel_text_address(info->prev_ip)); |
1da177e4 LT |
289 | |
290 | info->rp = 0; | |
291 | ||
292 | dbg("analyzing func @ %lx with no unwind info, setting " | |
293 | "prev_sp=%lx prev_ip=%lx\n", info->ip, | |
294 | info->prev_sp, info->prev_ip); | |
295 | } else { | |
296 | dbg("e->start = 0x%x, e->end = 0x%x, Save_SP = %d, " | |
297 | "Save_RP = %d, Millicode = %d size = %u\n", | |
298 | e->region_start, e->region_end, e->Save_SP, e->Save_RP, | |
299 | e->Millicode, e->Total_frame_size); | |
300 | ||
301 | looking_for_rp = e->Save_RP; | |
302 | ||
303 | for (npc = e->region_start; | |
304 | (frame_size < (e->Total_frame_size << 3) || | |
305 | looking_for_rp) && | |
306 | npc < info->ip; | |
307 | npc += 4) { | |
308 | ||
309 | insn = *(unsigned int *)npc; | |
310 | ||
be24a897 MP |
311 | if ((insn & 0xffffc001) == 0x37de0000 || |
312 | (insn & 0xffe00001) == 0x6fc00000) { | |
1da177e4 | 313 | /* ldo X(sp), sp, or stwm X,D(sp) */ |
be24a897 | 314 | frame_size += (insn & 0x3fff) >> 1; |
1da177e4 LT |
315 | dbg("analyzing func @ %lx, insn=%08x @ " |
316 | "%lx, frame_size = %ld\n", info->ip, | |
317 | insn, npc, frame_size); | |
be24a897 | 318 | } else if ((insn & 0xffe00009) == 0x73c00008) { |
1da177e4 | 319 | /* std,ma X,D(sp) */ |
be24a897 | 320 | frame_size += ((insn >> 4) & 0x3ff) << 3; |
1da177e4 LT |
321 | dbg("analyzing func @ %lx, insn=%08x @ " |
322 | "%lx, frame_size = %ld\n", info->ip, | |
323 | insn, npc, frame_size); | |
324 | } else if (insn == 0x6bc23fd9) { | |
325 | /* stw rp,-20(sp) */ | |
326 | rpoffset = 20; | |
327 | looking_for_rp = 0; | |
328 | dbg("analyzing func @ %lx, insn=stw rp," | |
329 | "-20(sp) @ %lx\n", info->ip, npc); | |
330 | } else if (insn == 0x0fc212c1) { | |
331 | /* std rp,-16(sr0,sp) */ | |
332 | rpoffset = 16; | |
333 | looking_for_rp = 0; | |
334 | dbg("analyzing func @ %lx, insn=std rp," | |
335 | "-16(sp) @ %lx\n", info->ip, npc); | |
336 | } | |
337 | } | |
338 | ||
be24a897 MP |
339 | if (frame_size > e->Total_frame_size << 3) |
340 | frame_size = e->Total_frame_size << 3; | |
341 | ||
05dc16d6 RC |
342 | if (!unwind_special(info, e->region_start, frame_size)) { |
343 | info->prev_sp = info->sp - frame_size; | |
344 | if (e->Millicode) | |
345 | info->rp = info->r31; | |
346 | else if (rpoffset) | |
347 | info->rp = *(unsigned long *)(info->prev_sp - rpoffset); | |
348 | info->prev_ip = info->rp; | |
349 | info->rp = 0; | |
350 | } | |
1da177e4 LT |
351 | |
352 | dbg("analyzing func @ %lx, setting prev_sp=%lx " | |
353 | "prev_ip=%lx npc=%lx\n", info->ip, info->prev_sp, | |
354 | info->prev_ip, npc); | |
355 | } | |
356 | } | |
357 | ||
358 | void unwind_frame_init(struct unwind_frame_info *info, struct task_struct *t, | |
359 | struct pt_regs *regs) | |
360 | { | |
361 | memset(info, 0, sizeof(struct unwind_frame_info)); | |
362 | info->t = t; | |
363 | info->sp = regs->gr[30]; | |
364 | info->ip = regs->iaoq[0]; | |
365 | info->rp = regs->gr[2]; | |
366 | info->r31 = regs->gr[31]; | |
367 | ||
368 | dbg("(%d) Start unwind from sp=%08lx ip=%08lx\n", | |
369 | t ? (int)t->pid : -1, info->sp, info->ip); | |
370 | } | |
371 | ||
372 | void unwind_frame_init_from_blocked_task(struct unwind_frame_info *info, struct task_struct *t) | |
373 | { | |
374 | struct pt_regs *r = &t->thread.regs; | |
375 | struct pt_regs *r2; | |
376 | ||
e0e7ed48 | 377 | r2 = kmalloc(sizeof(struct pt_regs), GFP_ATOMIC); |
1da177e4 LT |
378 | if (!r2) |
379 | return; | |
380 | *r2 = *r; | |
381 | r2->gr[30] = r->ksp; | |
382 | r2->iaoq[0] = r->kpc; | |
383 | unwind_frame_init(info, t, r2); | |
384 | kfree(r2); | |
385 | } | |
386 | ||
387 | void unwind_frame_init_running(struct unwind_frame_info *info, struct pt_regs *regs) | |
388 | { | |
389 | unwind_frame_init(info, current, regs); | |
390 | } | |
391 | ||
392 | int unwind_once(struct unwind_frame_info *next_frame) | |
393 | { | |
394 | unwind_frame_regs(next_frame); | |
395 | ||
396 | if (next_frame->prev_sp == 0 || | |
397 | next_frame->prev_ip == 0) | |
398 | return -1; | |
399 | ||
400 | next_frame->sp = next_frame->prev_sp; | |
401 | next_frame->ip = next_frame->prev_ip; | |
402 | next_frame->prev_sp = 0; | |
403 | next_frame->prev_ip = 0; | |
404 | ||
405 | dbg("(%d) Continue unwind to sp=%08lx ip=%08lx\n", | |
406 | next_frame->t ? (int)next_frame->t->pid : -1, | |
407 | next_frame->sp, next_frame->ip); | |
408 | ||
409 | return 0; | |
410 | } | |
411 | ||
412 | int unwind_to_user(struct unwind_frame_info *info) | |
413 | { | |
414 | int ret; | |
415 | ||
416 | do { | |
417 | ret = unwind_once(info); | |
418 | } while (!ret && !(info->ip & 3)); | |
419 | ||
420 | return ret; | |
421 | } | |
11e17809 HD |
422 | |
423 | unsigned long return_address(unsigned int level) | |
424 | { | |
425 | struct unwind_frame_info info; | |
426 | struct pt_regs r; | |
427 | unsigned long sp; | |
428 | ||
429 | /* initialize unwind info */ | |
430 | asm volatile ("copy %%r30, %0" : "=r"(sp)); | |
431 | memset(&r, 0, sizeof(struct pt_regs)); | |
432 | r.iaoq[0] = (unsigned long) current_text_addr(); | |
433 | r.gr[2] = (unsigned long) __builtin_return_address(0); | |
434 | r.gr[30] = sp; | |
435 | unwind_frame_init(&info, current, &r); | |
436 | ||
437 | /* unwind stack */ | |
438 | ++level; | |
439 | do { | |
440 | if (unwind_once(&info) < 0 || info.ip == 0) | |
441 | return 0; | |
c790b41b | 442 | if (!kernel_text_address(info.ip)) |
11e17809 | 443 | return 0; |
11e17809 HD |
444 | } while (info.ip && level--); |
445 | ||
446 | return info.ip; | |
447 | } |