Commit | Line | Data |
---|---|---|
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> | |
16 | ||
17 | #include <asm/uaccess.h> | |
18 | #include <asm/assembly.h> | |
05dc16d6 RC |
19 | #include <asm/asm-offsets.h> |
20 | #include <asm/ptrace.h> | |
1da177e4 LT |
21 | |
22 | #include <asm/unwind.h> | |
23 | ||
24 | /* #define DEBUG 1 */ | |
25 | #ifdef DEBUG | |
26 | #define dbg(x...) printk(x) | |
27 | #else | |
28 | #define dbg(x...) | |
29 | #endif | |
30 | ||
e036306a RC |
31 | #define KERNEL_START (KERNEL_BINARY_TEXT_START - 0x1000) |
32 | ||
1da177e4 LT |
33 | extern struct unwind_table_entry __start___unwind[]; |
34 | extern struct unwind_table_entry __stop___unwind[]; | |
35 | ||
36 | static spinlock_t unwind_lock; | |
37 | /* | |
38 | * the kernel unwind block is not dynamically allocated so that | |
39 | * we can call unwind_init as early in the bootup process as | |
40 | * possible (before the slab allocator is initialized) | |
41 | */ | |
8039de10 | 42 | static struct unwind_table kernel_unwind_table __read_mostly; |
1da177e4 LT |
43 | static LIST_HEAD(unwind_tables); |
44 | ||
45 | static inline const struct unwind_table_entry * | |
46 | find_unwind_entry_in_table(const struct unwind_table *table, unsigned long addr) | |
47 | { | |
48 | const struct unwind_table_entry *e = NULL; | |
49 | unsigned long lo, hi, mid; | |
50 | ||
51 | lo = 0; | |
52 | hi = table->length - 1; | |
53 | ||
54 | while (lo <= hi) { | |
55 | mid = (hi - lo) / 2 + lo; | |
56 | e = &table->table[mid]; | |
57 | if (addr < e->region_start) | |
58 | hi = mid - 1; | |
59 | else if (addr > e->region_end) | |
60 | lo = mid + 1; | |
61 | else | |
62 | return e; | |
63 | } | |
64 | ||
65 | return NULL; | |
66 | } | |
67 | ||
68 | static const struct unwind_table_entry * | |
69 | find_unwind_entry(unsigned long addr) | |
70 | { | |
71 | struct unwind_table *table; | |
72 | const struct unwind_table_entry *e = NULL; | |
73 | ||
74 | if (addr >= kernel_unwind_table.start && | |
75 | addr <= kernel_unwind_table.end) | |
76 | e = find_unwind_entry_in_table(&kernel_unwind_table, addr); | |
77 | else | |
78 | list_for_each_entry(table, &unwind_tables, list) { | |
79 | if (addr >= table->start && | |
80 | addr <= table->end) | |
81 | e = find_unwind_entry_in_table(table, addr); | |
82 | if (e) | |
83 | break; | |
84 | } | |
85 | ||
86 | return e; | |
87 | } | |
88 | ||
89 | static void | |
90 | unwind_table_init(struct unwind_table *table, const char *name, | |
91 | unsigned long base_addr, unsigned long gp, | |
92 | void *table_start, void *table_end) | |
93 | { | |
94 | struct unwind_table_entry *start = table_start; | |
95 | struct unwind_table_entry *end = | |
96 | (struct unwind_table_entry *)table_end - 1; | |
97 | ||
98 | table->name = name; | |
99 | table->base_addr = base_addr; | |
100 | table->gp = gp; | |
101 | table->start = base_addr + start->region_start; | |
102 | table->end = base_addr + end->region_end; | |
103 | table->table = (struct unwind_table_entry *)table_start; | |
104 | table->length = end - start + 1; | |
105 | INIT_LIST_HEAD(&table->list); | |
106 | ||
107 | for (; start <= end; start++) { | |
108 | if (start < end && | |
109 | start->region_end > (start+1)->region_start) { | |
110 | printk("WARNING: Out of order unwind entry! %p and %p\n", start, start+1); | |
111 | } | |
112 | ||
113 | start->region_start += base_addr; | |
114 | start->region_end += base_addr; | |
115 | } | |
116 | } | |
117 | ||
118 | static void | |
119 | unwind_table_sort(struct unwind_table_entry *start, | |
120 | struct unwind_table_entry *finish) | |
121 | { | |
122 | struct unwind_table_entry el, *p, *q; | |
123 | ||
124 | for (p = start + 1; p < finish; ++p) { | |
125 | if (p[0].region_start < p[-1].region_start) { | |
126 | el = *p; | |
127 | q = p; | |
128 | do { | |
129 | q[0] = q[-1]; | |
130 | --q; | |
131 | } while (q > start && | |
132 | el.region_start < q[-1].region_start); | |
133 | *q = el; | |
134 | } | |
135 | } | |
136 | } | |
137 | ||
138 | struct unwind_table * | |
139 | unwind_table_add(const char *name, unsigned long base_addr, | |
140 | unsigned long gp, | |
141 | void *start, void *end) | |
142 | { | |
143 | struct unwind_table *table; | |
144 | unsigned long flags; | |
145 | struct unwind_table_entry *s = (struct unwind_table_entry *)start; | |
146 | struct unwind_table_entry *e = (struct unwind_table_entry *)end; | |
147 | ||
148 | unwind_table_sort(s, e); | |
149 | ||
150 | table = kmalloc(sizeof(struct unwind_table), GFP_USER); | |
151 | if (table == NULL) | |
152 | return NULL; | |
153 | unwind_table_init(table, name, base_addr, gp, start, end); | |
154 | spin_lock_irqsave(&unwind_lock, flags); | |
155 | list_add_tail(&table->list, &unwind_tables); | |
156 | spin_unlock_irqrestore(&unwind_lock, flags); | |
157 | ||
158 | return table; | |
159 | } | |
160 | ||
161 | void unwind_table_remove(struct unwind_table *table) | |
162 | { | |
163 | unsigned long flags; | |
164 | ||
165 | spin_lock_irqsave(&unwind_lock, flags); | |
166 | list_del(&table->list); | |
167 | spin_unlock_irqrestore(&unwind_lock, flags); | |
168 | ||
169 | kfree(table); | |
170 | } | |
171 | ||
172 | /* Called from setup_arch to import the kernel unwind info */ | |
f0514ae3 | 173 | int unwind_init(void) |
1da177e4 LT |
174 | { |
175 | long start, stop; | |
176 | register unsigned long gp __asm__ ("r27"); | |
177 | ||
178 | start = (long)&__start___unwind[0]; | |
179 | stop = (long)&__stop___unwind[0]; | |
180 | ||
181 | spin_lock_init(&unwind_lock); | |
182 | ||
183 | printk("unwind_init: start = 0x%lx, end = 0x%lx, entries = %lu\n", | |
184 | start, stop, | |
185 | (stop - start) / sizeof(struct unwind_table_entry)); | |
186 | ||
187 | unwind_table_init(&kernel_unwind_table, "kernel", KERNEL_START, | |
188 | gp, | |
189 | &__start___unwind[0], &__stop___unwind[0]); | |
190 | #if 0 | |
191 | { | |
192 | int i; | |
193 | for (i = 0; i < 10; i++) | |
194 | { | |
195 | printk("region 0x%x-0x%x\n", | |
196 | __start___unwind[i].region_start, | |
197 | __start___unwind[i].region_end); | |
198 | } | |
199 | } | |
200 | #endif | |
201 | return 0; | |
202 | } | |
203 | ||
05dc16d6 RC |
204 | #ifdef CONFIG_64BIT |
205 | #define get_func_addr(fptr) fptr[2] | |
206 | #else | |
207 | #define get_func_addr(fptr) fptr[0] | |
208 | #endif | |
209 | ||
210 | static int unwind_special(struct unwind_frame_info *info, unsigned long pc, int frame_size) | |
211 | { | |
78199943 KM |
212 | extern void handle_interruption(int, struct pt_regs *); |
213 | static unsigned long *hi = (unsigned long *)&handle_interruption; | |
05dc16d6 RC |
214 | |
215 | if (pc == get_func_addr(hi)) { | |
216 | struct pt_regs *regs = (struct pt_regs *)(info->sp - frame_size - PT_SZ_ALGN); | |
217 | dbg("Unwinding through handle_interruption()\n"); | |
218 | info->prev_sp = regs->gr[30]; | |
219 | info->prev_ip = regs->iaoq[0]; | |
220 | ||
221 | return 1; | |
222 | } | |
223 | ||
224 | return 0; | |
225 | } | |
226 | ||
1da177e4 LT |
227 | static void unwind_frame_regs(struct unwind_frame_info *info) |
228 | { | |
229 | const struct unwind_table_entry *e; | |
230 | unsigned long npc; | |
231 | unsigned int insn; | |
232 | long frame_size = 0; | |
233 | int looking_for_rp, rpoffset = 0; | |
234 | ||
235 | e = find_unwind_entry(info->ip); | |
236 | if (e == NULL) { | |
237 | unsigned long sp; | |
238 | extern char _stext[], _etext[]; | |
239 | ||
240 | dbg("Cannot find unwind entry for 0x%lx; forced unwinding\n", info->ip); | |
241 | ||
242 | #ifdef CONFIG_KALLSYMS | |
243 | /* Handle some frequent special cases.... */ | |
244 | { | |
9281acea | 245 | char symname[KSYM_NAME_LEN]; |
cb957795 | 246 | char *modname; |
1da177e4 | 247 | |
cb957795 KM |
248 | kallsyms_lookup(info->ip, NULL, NULL, &modname, |
249 | symname); | |
1da177e4 LT |
250 | |
251 | dbg("info->ip = 0x%lx, name = %s\n", info->ip, symname); | |
252 | ||
253 | if (strcmp(symname, "_switch_to_ret") == 0) { | |
254 | info->prev_sp = info->sp - CALLEE_SAVE_FRAME_SIZE; | |
255 | info->prev_ip = *(unsigned long *)(info->prev_sp - RP_OFFSET); | |
256 | dbg("_switch_to_ret @ %lx - setting " | |
257 | "prev_sp=%lx prev_ip=%lx\n", | |
258 | info->ip, info->prev_sp, | |
259 | info->prev_ip); | |
260 | return; | |
261 | } else if (strcmp(symname, "ret_from_kernel_thread") == 0 || | |
262 | strcmp(symname, "syscall_exit") == 0) { | |
263 | info->prev_ip = info->prev_sp = 0; | |
264 | return; | |
265 | } | |
266 | } | |
267 | #endif | |
268 | ||
269 | /* Since we are doing the unwinding blind, we don't know if | |
270 | we are adjusting the stack correctly or extracting the rp | |
271 | correctly. The rp is checked to see if it belongs to the | |
272 | kernel text section, if not we assume we don't have a | |
273 | correct stack frame and we continue to unwind the stack. | |
274 | This is not quite correct, and will fail for loadable | |
275 | modules. */ | |
276 | sp = info->sp & ~63; | |
277 | do { | |
278 | unsigned long tmp; | |
279 | ||
280 | info->prev_sp = sp - 64; | |
281 | info->prev_ip = 0; | |
282 | if (get_user(tmp, (unsigned long *)(info->prev_sp - RP_OFFSET))) | |
283 | break; | |
284 | info->prev_ip = tmp; | |
285 | sp = info->prev_sp; | |
286 | } while (info->prev_ip < (unsigned long)_stext || | |
287 | info->prev_ip > (unsigned long)_etext); | |
288 | ||
289 | info->rp = 0; | |
290 | ||
291 | dbg("analyzing func @ %lx with no unwind info, setting " | |
292 | "prev_sp=%lx prev_ip=%lx\n", info->ip, | |
293 | info->prev_sp, info->prev_ip); | |
294 | } else { | |
295 | dbg("e->start = 0x%x, e->end = 0x%x, Save_SP = %d, " | |
296 | "Save_RP = %d, Millicode = %d size = %u\n", | |
297 | e->region_start, e->region_end, e->Save_SP, e->Save_RP, | |
298 | e->Millicode, e->Total_frame_size); | |
299 | ||
300 | looking_for_rp = e->Save_RP; | |
301 | ||
302 | for (npc = e->region_start; | |
303 | (frame_size < (e->Total_frame_size << 3) || | |
304 | looking_for_rp) && | |
305 | npc < info->ip; | |
306 | npc += 4) { | |
307 | ||
308 | insn = *(unsigned int *)npc; | |
309 | ||
310 | if ((insn & 0xffffc000) == 0x37de0000 || | |
311 | (insn & 0xffe00000) == 0x6fc00000) { | |
312 | /* ldo X(sp), sp, or stwm X,D(sp) */ | |
313 | frame_size += (insn & 0x1 ? -1 << 13 : 0) | | |
314 | ((insn & 0x3fff) >> 1); | |
315 | dbg("analyzing func @ %lx, insn=%08x @ " | |
316 | "%lx, frame_size = %ld\n", info->ip, | |
317 | insn, npc, frame_size); | |
318 | } else if ((insn & 0xffe00008) == 0x73c00008) { | |
319 | /* std,ma X,D(sp) */ | |
320 | frame_size += (insn & 0x1 ? -1 << 13 : 0) | | |
321 | (((insn >> 4) & 0x3ff) << 3); | |
322 | dbg("analyzing func @ %lx, insn=%08x @ " | |
323 | "%lx, frame_size = %ld\n", info->ip, | |
324 | insn, npc, frame_size); | |
325 | } else if (insn == 0x6bc23fd9) { | |
326 | /* stw rp,-20(sp) */ | |
327 | rpoffset = 20; | |
328 | looking_for_rp = 0; | |
329 | dbg("analyzing func @ %lx, insn=stw rp," | |
330 | "-20(sp) @ %lx\n", info->ip, npc); | |
331 | } else if (insn == 0x0fc212c1) { | |
332 | /* std rp,-16(sr0,sp) */ | |
333 | rpoffset = 16; | |
334 | looking_for_rp = 0; | |
335 | dbg("analyzing func @ %lx, insn=std rp," | |
336 | "-16(sp) @ %lx\n", info->ip, npc); | |
337 | } | |
338 | } | |
339 | ||
05dc16d6 RC |
340 | if (!unwind_special(info, e->region_start, frame_size)) { |
341 | info->prev_sp = info->sp - frame_size; | |
342 | if (e->Millicode) | |
343 | info->rp = info->r31; | |
344 | else if (rpoffset) | |
345 | info->rp = *(unsigned long *)(info->prev_sp - rpoffset); | |
346 | info->prev_ip = info->rp; | |
347 | info->rp = 0; | |
348 | } | |
1da177e4 LT |
349 | |
350 | dbg("analyzing func @ %lx, setting prev_sp=%lx " | |
351 | "prev_ip=%lx npc=%lx\n", info->ip, info->prev_sp, | |
352 | info->prev_ip, npc); | |
353 | } | |
354 | } | |
355 | ||
356 | void unwind_frame_init(struct unwind_frame_info *info, struct task_struct *t, | |
357 | struct pt_regs *regs) | |
358 | { | |
359 | memset(info, 0, sizeof(struct unwind_frame_info)); | |
360 | info->t = t; | |
361 | info->sp = regs->gr[30]; | |
362 | info->ip = regs->iaoq[0]; | |
363 | info->rp = regs->gr[2]; | |
364 | info->r31 = regs->gr[31]; | |
365 | ||
366 | dbg("(%d) Start unwind from sp=%08lx ip=%08lx\n", | |
367 | t ? (int)t->pid : -1, info->sp, info->ip); | |
368 | } | |
369 | ||
370 | void unwind_frame_init_from_blocked_task(struct unwind_frame_info *info, struct task_struct *t) | |
371 | { | |
372 | struct pt_regs *r = &t->thread.regs; | |
373 | struct pt_regs *r2; | |
374 | ||
5cbded58 | 375 | r2 = kmalloc(sizeof(struct pt_regs), GFP_KERNEL); |
1da177e4 LT |
376 | if (!r2) |
377 | return; | |
378 | *r2 = *r; | |
379 | r2->gr[30] = r->ksp; | |
380 | r2->iaoq[0] = r->kpc; | |
381 | unwind_frame_init(info, t, r2); | |
382 | kfree(r2); | |
383 | } | |
384 | ||
385 | void unwind_frame_init_running(struct unwind_frame_info *info, struct pt_regs *regs) | |
386 | { | |
387 | unwind_frame_init(info, current, regs); | |
388 | } | |
389 | ||
390 | int unwind_once(struct unwind_frame_info *next_frame) | |
391 | { | |
392 | unwind_frame_regs(next_frame); | |
393 | ||
394 | if (next_frame->prev_sp == 0 || | |
395 | next_frame->prev_ip == 0) | |
396 | return -1; | |
397 | ||
398 | next_frame->sp = next_frame->prev_sp; | |
399 | next_frame->ip = next_frame->prev_ip; | |
400 | next_frame->prev_sp = 0; | |
401 | next_frame->prev_ip = 0; | |
402 | ||
403 | dbg("(%d) Continue unwind to sp=%08lx ip=%08lx\n", | |
404 | next_frame->t ? (int)next_frame->t->pid : -1, | |
405 | next_frame->sp, next_frame->ip); | |
406 | ||
407 | return 0; | |
408 | } | |
409 | ||
410 | int unwind_to_user(struct unwind_frame_info *info) | |
411 | { | |
412 | int ret; | |
413 | ||
414 | do { | |
415 | ret = unwind_once(info); | |
416 | } while (!ret && !(info->ip & 3)); | |
417 | ||
418 | return ret; | |
419 | } |