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1da177e4 LT |
1 | /* arch/sparc64/kernel/kprobes.c |
2 | * | |
3 | * Copyright (C) 2004 David S. Miller <davem@davemloft.net> | |
4 | */ | |
5 | ||
6 | #include <linux/config.h> | |
7 | #include <linux/kernel.h> | |
8 | #include <linux/kprobes.h> | |
1da177e4 LT |
9 | #include <asm/kdebug.h> |
10 | #include <asm/signal.h> | |
11 | ||
12 | /* We do not have hardware single-stepping on sparc64. | |
13 | * So we implement software single-stepping with breakpoint | |
14 | * traps. The top-level scheme is similar to that used | |
15 | * in the x86 kprobes implementation. | |
16 | * | |
17 | * In the kprobe->ainsn.insn[] array we store the original | |
18 | * instruction at index zero and a break instruction at | |
19 | * index one. | |
20 | * | |
21 | * When we hit a kprobe we: | |
22 | * - Run the pre-handler | |
23 | * - Remember "regs->tnpc" and interrupt level stored in | |
24 | * "regs->tstate" so we can restore them later | |
25 | * - Disable PIL interrupts | |
26 | * - Set regs->tpc to point to kprobe->ainsn.insn[0] | |
27 | * - Set regs->tnpc to point to kprobe->ainsn.insn[1] | |
28 | * - Mark that we are actively in a kprobe | |
29 | * | |
30 | * At this point we wait for the second breakpoint at | |
31 | * kprobe->ainsn.insn[1] to hit. When it does we: | |
32 | * - Run the post-handler | |
33 | * - Set regs->tpc to "remembered" regs->tnpc stored above, | |
34 | * restore the PIL interrupt level in "regs->tstate" as well | |
35 | * - Make any adjustments necessary to regs->tnpc in order | |
36 | * to handle relative branches correctly. See below. | |
37 | * - Mark that we are no longer actively in a kprobe. | |
38 | */ | |
39 | ||
40 | int arch_prepare_kprobe(struct kprobe *p) | |
41 | { | |
42 | return 0; | |
43 | } | |
44 | ||
45 | void arch_copy_kprobe(struct kprobe *p) | |
46 | { | |
47 | p->ainsn.insn[0] = *p->addr; | |
48 | p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2; | |
7e1048b1 RL |
49 | p->opcode = *p->addr; |
50 | } | |
51 | ||
52 | void arch_arm_kprobe(struct kprobe *p) | |
53 | { | |
54 | *p->addr = BREAKPOINT_INSTRUCTION; | |
55 | flushi(p->addr); | |
56 | } | |
57 | ||
58 | void arch_disarm_kprobe(struct kprobe *p) | |
59 | { | |
60 | *p->addr = p->opcode; | |
61 | flushi(p->addr); | |
1da177e4 LT |
62 | } |
63 | ||
64 | void arch_remove_kprobe(struct kprobe *p) | |
65 | { | |
66 | } | |
67 | ||
1da177e4 LT |
68 | static struct kprobe *current_kprobe; |
69 | static unsigned long current_kprobe_orig_tnpc; | |
70 | static unsigned long current_kprobe_orig_tstate_pil; | |
71 | static unsigned int kprobe_status; | |
e539c233 PP |
72 | static struct kprobe *kprobe_prev; |
73 | static unsigned long kprobe_orig_tnpc_prev; | |
74 | static unsigned long kprobe_orig_tstate_pil_prev; | |
75 | static unsigned int kprobe_status_prev; | |
1da177e4 | 76 | |
e539c233 PP |
77 | static inline void save_previous_kprobe(void) |
78 | { | |
79 | kprobe_status_prev = kprobe_status; | |
80 | kprobe_orig_tnpc_prev = current_kprobe_orig_tnpc; | |
81 | kprobe_orig_tstate_pil_prev = current_kprobe_orig_tstate_pil; | |
82 | kprobe_prev = current_kprobe; | |
83 | } | |
84 | ||
85 | static inline void restore_previous_kprobe(void) | |
86 | { | |
87 | kprobe_status = kprobe_status_prev; | |
88 | current_kprobe_orig_tnpc = kprobe_orig_tnpc_prev; | |
89 | current_kprobe_orig_tstate_pil = kprobe_orig_tstate_pil_prev; | |
90 | current_kprobe = kprobe_prev; | |
91 | } | |
92 | ||
93 | static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs) | |
1da177e4 LT |
94 | { |
95 | current_kprobe_orig_tnpc = regs->tnpc; | |
96 | current_kprobe_orig_tstate_pil = (regs->tstate & TSTATE_PIL); | |
e539c233 PP |
97 | current_kprobe = p; |
98 | } | |
99 | ||
100 | static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) | |
101 | { | |
1da177e4 LT |
102 | regs->tstate |= TSTATE_PIL; |
103 | ||
104 | /*single step inline, if it a breakpoint instruction*/ | |
105 | if (p->opcode == BREAKPOINT_INSTRUCTION) { | |
106 | regs->tpc = (unsigned long) p->addr; | |
107 | regs->tnpc = current_kprobe_orig_tnpc; | |
108 | } else { | |
109 | regs->tpc = (unsigned long) &p->ainsn.insn[0]; | |
110 | regs->tnpc = (unsigned long) &p->ainsn.insn[1]; | |
111 | } | |
112 | } | |
113 | ||
1da177e4 LT |
114 | static int kprobe_handler(struct pt_regs *regs) |
115 | { | |
116 | struct kprobe *p; | |
117 | void *addr = (void *) regs->tpc; | |
118 | int ret = 0; | |
119 | ||
120 | preempt_disable(); | |
121 | ||
122 | if (kprobe_running()) { | |
123 | /* We *are* holding lock here, so this is safe. | |
124 | * Disarm the probe we just hit, and ignore it. | |
125 | */ | |
126 | p = get_kprobe(addr); | |
127 | if (p) { | |
128 | if (kprobe_status == KPROBE_HIT_SS) { | |
129 | regs->tstate = ((regs->tstate & ~TSTATE_PIL) | | |
130 | current_kprobe_orig_tstate_pil); | |
131 | unlock_kprobes(); | |
132 | goto no_kprobe; | |
133 | } | |
e539c233 PP |
134 | /* We have reentered the kprobe_handler(), since |
135 | * another probe was hit while within the handler. | |
136 | * We here save the original kprobes variables and | |
137 | * just single step on the instruction of the new probe | |
138 | * without calling any user handlers. | |
139 | */ | |
140 | save_previous_kprobe(); | |
141 | set_current_kprobe(p, regs); | |
142 | p->nmissed++; | |
143 | kprobe_status = KPROBE_REENTER; | |
144 | prepare_singlestep(p, regs); | |
145 | return 1; | |
1da177e4 LT |
146 | } else { |
147 | p = current_kprobe; | |
148 | if (p->break_handler && p->break_handler(p, regs)) | |
149 | goto ss_probe; | |
150 | } | |
151 | /* If it's not ours, can't be delete race, (we hold lock). */ | |
152 | goto no_kprobe; | |
153 | } | |
154 | ||
155 | lock_kprobes(); | |
156 | p = get_kprobe(addr); | |
157 | if (!p) { | |
158 | unlock_kprobes(); | |
159 | if (*(u32 *)addr != BREAKPOINT_INSTRUCTION) { | |
160 | /* | |
161 | * The breakpoint instruction was removed right | |
162 | * after we hit it. Another cpu has removed | |
163 | * either a probepoint or a debugger breakpoint | |
164 | * at this address. In either case, no further | |
165 | * handling of this interrupt is appropriate. | |
166 | */ | |
167 | ret = 1; | |
168 | } | |
169 | /* Not one of ours: let kernel handle it */ | |
170 | goto no_kprobe; | |
171 | } | |
172 | ||
e539c233 | 173 | set_current_kprobe(p, regs); |
1da177e4 | 174 | kprobe_status = KPROBE_HIT_ACTIVE; |
1da177e4 LT |
175 | if (p->pre_handler && p->pre_handler(p, regs)) |
176 | return 1; | |
177 | ||
178 | ss_probe: | |
179 | prepare_singlestep(p, regs); | |
180 | kprobe_status = KPROBE_HIT_SS; | |
181 | return 1; | |
182 | ||
183 | no_kprobe: | |
184 | preempt_enable_no_resched(); | |
185 | return ret; | |
186 | } | |
187 | ||
188 | /* If INSN is a relative control transfer instruction, | |
189 | * return the corrected branch destination value. | |
190 | * | |
191 | * The original INSN location was REAL_PC, it actually | |
192 | * executed at PC and produced destination address NPC. | |
193 | */ | |
194 | static unsigned long relbranch_fixup(u32 insn, unsigned long real_pc, | |
195 | unsigned long pc, unsigned long npc) | |
196 | { | |
197 | /* Branch not taken, no mods necessary. */ | |
198 | if (npc == pc + 0x4UL) | |
199 | return real_pc + 0x4UL; | |
200 | ||
201 | /* The three cases are call, branch w/prediction, | |
202 | * and traditional branch. | |
203 | */ | |
204 | if ((insn & 0xc0000000) == 0x40000000 || | |
205 | (insn & 0xc1c00000) == 0x00400000 || | |
206 | (insn & 0xc1c00000) == 0x00800000) { | |
207 | /* The instruction did all the work for us | |
208 | * already, just apply the offset to the correct | |
209 | * instruction location. | |
210 | */ | |
211 | return (real_pc + (npc - pc)); | |
212 | } | |
213 | ||
214 | return real_pc + 0x4UL; | |
215 | } | |
216 | ||
217 | /* If INSN is an instruction which writes it's PC location | |
218 | * into a destination register, fix that up. | |
219 | */ | |
220 | static void retpc_fixup(struct pt_regs *regs, u32 insn, unsigned long real_pc) | |
221 | { | |
222 | unsigned long *slot = NULL; | |
223 | ||
224 | /* Simplest cast is call, which always uses %o7 */ | |
225 | if ((insn & 0xc0000000) == 0x40000000) { | |
226 | slot = ®s->u_regs[UREG_I7]; | |
227 | } | |
228 | ||
229 | /* Jmpl encodes the register inside of the opcode */ | |
230 | if ((insn & 0xc1f80000) == 0x81c00000) { | |
231 | unsigned long rd = ((insn >> 25) & 0x1f); | |
232 | ||
233 | if (rd <= 15) { | |
234 | slot = ®s->u_regs[rd]; | |
235 | } else { | |
236 | /* Hard case, it goes onto the stack. */ | |
237 | flushw_all(); | |
238 | ||
239 | rd -= 16; | |
240 | slot = (unsigned long *) | |
241 | (regs->u_regs[UREG_FP] + STACK_BIAS); | |
242 | slot += rd; | |
243 | } | |
244 | } | |
245 | if (slot != NULL) | |
246 | *slot = real_pc; | |
247 | } | |
248 | ||
249 | /* | |
250 | * Called after single-stepping. p->addr is the address of the | |
251 | * instruction whose first byte has been replaced by the breakpoint | |
252 | * instruction. To avoid the SMP problems that can occur when we | |
253 | * temporarily put back the original opcode to single-step, we | |
254 | * single-stepped a copy of the instruction. The address of this | |
255 | * copy is p->ainsn.insn. | |
256 | * | |
257 | * This function prepares to return from the post-single-step | |
258 | * breakpoint trap. | |
259 | */ | |
260 | static void resume_execution(struct kprobe *p, struct pt_regs *regs) | |
261 | { | |
262 | u32 insn = p->ainsn.insn[0]; | |
263 | ||
264 | regs->tpc = current_kprobe_orig_tnpc; | |
265 | regs->tnpc = relbranch_fixup(insn, | |
266 | (unsigned long) p->addr, | |
267 | (unsigned long) &p->ainsn.insn[0], | |
268 | regs->tnpc); | |
269 | retpc_fixup(regs, insn, (unsigned long) p->addr); | |
270 | ||
271 | regs->tstate = ((regs->tstate & ~TSTATE_PIL) | | |
272 | current_kprobe_orig_tstate_pil); | |
273 | } | |
274 | ||
275 | static inline int post_kprobe_handler(struct pt_regs *regs) | |
276 | { | |
277 | if (!kprobe_running()) | |
278 | return 0; | |
279 | ||
e539c233 PP |
280 | if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) { |
281 | kprobe_status = KPROBE_HIT_SSDONE; | |
1da177e4 | 282 | current_kprobe->post_handler(current_kprobe, regs, 0); |
e539c233 | 283 | } |
1da177e4 LT |
284 | |
285 | resume_execution(current_kprobe, regs); | |
286 | ||
e539c233 PP |
287 | /*Restore back the original saved kprobes variables and continue. */ |
288 | if (kprobe_status == KPROBE_REENTER) { | |
289 | restore_previous_kprobe(); | |
290 | goto out; | |
291 | } | |
1da177e4 | 292 | unlock_kprobes(); |
e539c233 | 293 | out: |
1da177e4 LT |
294 | preempt_enable_no_resched(); |
295 | ||
296 | return 1; | |
297 | } | |
298 | ||
299 | /* Interrupts disabled, kprobe_lock held. */ | |
300 | static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) | |
301 | { | |
302 | if (current_kprobe->fault_handler | |
303 | && current_kprobe->fault_handler(current_kprobe, regs, trapnr)) | |
304 | return 1; | |
305 | ||
306 | if (kprobe_status & KPROBE_HIT_SS) { | |
307 | resume_execution(current_kprobe, regs); | |
308 | ||
309 | unlock_kprobes(); | |
310 | preempt_enable_no_resched(); | |
311 | } | |
312 | return 0; | |
313 | } | |
314 | ||
315 | /* | |
316 | * Wrapper routine to for handling exceptions. | |
317 | */ | |
318 | int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, | |
319 | void *data) | |
320 | { | |
321 | struct die_args *args = (struct die_args *)data; | |
322 | switch (val) { | |
323 | case DIE_DEBUG: | |
324 | if (kprobe_handler(args->regs)) | |
325 | return NOTIFY_STOP; | |
326 | break; | |
327 | case DIE_DEBUG_2: | |
328 | if (post_kprobe_handler(args->regs)) | |
329 | return NOTIFY_STOP; | |
330 | break; | |
331 | case DIE_GPF: | |
332 | if (kprobe_running() && | |
333 | kprobe_fault_handler(args->regs, args->trapnr)) | |
334 | return NOTIFY_STOP; | |
335 | break; | |
336 | case DIE_PAGE_FAULT: | |
337 | if (kprobe_running() && | |
338 | kprobe_fault_handler(args->regs, args->trapnr)) | |
339 | return NOTIFY_STOP; | |
340 | break; | |
341 | default: | |
342 | break; | |
343 | } | |
344 | return NOTIFY_DONE; | |
345 | } | |
346 | ||
347 | asmlinkage void kprobe_trap(unsigned long trap_level, struct pt_regs *regs) | |
348 | { | |
349 | BUG_ON(trap_level != 0x170 && trap_level != 0x171); | |
350 | ||
351 | if (user_mode(regs)) { | |
352 | local_irq_enable(); | |
353 | bad_trap(regs, trap_level); | |
354 | return; | |
355 | } | |
356 | ||
357 | /* trap_level == 0x170 --> ta 0x70 | |
358 | * trap_level == 0x171 --> ta 0x71 | |
359 | */ | |
360 | if (notify_die((trap_level == 0x170) ? DIE_DEBUG : DIE_DEBUG_2, | |
361 | (trap_level == 0x170) ? "debug" : "debug_2", | |
362 | regs, 0, trap_level, SIGTRAP) != NOTIFY_STOP) | |
363 | bad_trap(regs, trap_level); | |
364 | } | |
365 | ||
366 | /* Jprobes support. */ | |
367 | static struct pt_regs jprobe_saved_regs; | |
368 | static struct pt_regs *jprobe_saved_regs_location; | |
369 | static struct sparc_stackf jprobe_saved_stack; | |
370 | ||
371 | int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) | |
372 | { | |
373 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
374 | ||
375 | jprobe_saved_regs_location = regs; | |
376 | memcpy(&jprobe_saved_regs, regs, sizeof(*regs)); | |
377 | ||
378 | /* Save a whole stack frame, this gets arguments | |
379 | * pushed onto the stack after using up all the | |
380 | * arg registers. | |
381 | */ | |
382 | memcpy(&jprobe_saved_stack, | |
383 | (char *) (regs->u_regs[UREG_FP] + STACK_BIAS), | |
384 | sizeof(jprobe_saved_stack)); | |
385 | ||
386 | regs->tpc = (unsigned long) jp->entry; | |
387 | regs->tnpc = ((unsigned long) jp->entry) + 0x4UL; | |
388 | regs->tstate |= TSTATE_PIL; | |
389 | ||
390 | return 1; | |
391 | } | |
392 | ||
393 | void jprobe_return(void) | |
394 | { | |
395 | preempt_enable_no_resched(); | |
396 | __asm__ __volatile__( | |
397 | ".globl jprobe_return_trap_instruction\n" | |
398 | "jprobe_return_trap_instruction:\n\t" | |
399 | "ta 0x70"); | |
400 | } | |
401 | ||
402 | extern void jprobe_return_trap_instruction(void); | |
403 | ||
404 | extern void __show_regs(struct pt_regs * regs); | |
405 | ||
406 | int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) | |
407 | { | |
408 | u32 *addr = (u32 *) regs->tpc; | |
409 | ||
410 | if (addr == (u32 *) jprobe_return_trap_instruction) { | |
411 | if (jprobe_saved_regs_location != regs) { | |
412 | printk("JPROBE: Current regs (%p) does not match " | |
413 | "saved regs (%p).\n", | |
414 | regs, jprobe_saved_regs_location); | |
415 | printk("JPROBE: Saved registers\n"); | |
416 | __show_regs(jprobe_saved_regs_location); | |
417 | printk("JPROBE: Current registers\n"); | |
418 | __show_regs(regs); | |
419 | BUG(); | |
420 | } | |
421 | /* Restore old register state. Do pt_regs | |
422 | * first so that UREG_FP is the original one for | |
423 | * the stack frame restore. | |
424 | */ | |
425 | memcpy(regs, &jprobe_saved_regs, sizeof(*regs)); | |
426 | ||
427 | memcpy((char *) (regs->u_regs[UREG_FP] + STACK_BIAS), | |
428 | &jprobe_saved_stack, | |
429 | sizeof(jprobe_saved_stack)); | |
430 | ||
431 | return 1; | |
432 | } | |
433 | return 0; | |
434 | } | |
e539c233 | 435 | |
6772926b RL |
436 | /* architecture specific initialization */ |
437 | int arch_init_kprobes(void) | |
438 | { | |
439 | return 0; | |
440 | } |