| 1 | /* |
| 2 | * Kernel Probes (KProbes) |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | * |
| 18 | * Copyright IBM Corp. 2002, 2006 |
| 19 | * |
| 20 | * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com> |
| 21 | */ |
| 22 | |
| 23 | #include <linux/kprobes.h> |
| 24 | #include <linux/ptrace.h> |
| 25 | #include <linux/preempt.h> |
| 26 | #include <linux/stop_machine.h> |
| 27 | #include <linux/kdebug.h> |
| 28 | #include <linux/uaccess.h> |
| 29 | #include <asm/cacheflush.h> |
| 30 | #include <asm/sections.h> |
| 31 | #include <linux/module.h> |
| 32 | #include <linux/slab.h> |
| 33 | #include <linux/hardirq.h> |
| 34 | |
| 35 | DEFINE_PER_CPU(struct kprobe *, current_kprobe); |
| 36 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
| 37 | |
| 38 | struct kretprobe_blackpoint kretprobe_blacklist[] = { }; |
| 39 | |
| 40 | static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn) |
| 41 | { |
| 42 | switch (insn[0] >> 8) { |
| 43 | case 0x0c: /* bassm */ |
| 44 | case 0x0b: /* bsm */ |
| 45 | case 0x83: /* diag */ |
| 46 | case 0x44: /* ex */ |
| 47 | case 0xac: /* stnsm */ |
| 48 | case 0xad: /* stosm */ |
| 49 | return -EINVAL; |
| 50 | } |
| 51 | switch (insn[0]) { |
| 52 | case 0x0101: /* pr */ |
| 53 | case 0xb25a: /* bsa */ |
| 54 | case 0xb240: /* bakr */ |
| 55 | case 0xb258: /* bsg */ |
| 56 | case 0xb218: /* pc */ |
| 57 | case 0xb228: /* pt */ |
| 58 | case 0xb98d: /* epsw */ |
| 59 | return -EINVAL; |
| 60 | } |
| 61 | return 0; |
| 62 | } |
| 63 | |
| 64 | static int __kprobes get_fixup_type(kprobe_opcode_t *insn) |
| 65 | { |
| 66 | /* default fixup method */ |
| 67 | int fixup = FIXUP_PSW_NORMAL; |
| 68 | |
| 69 | switch (insn[0] >> 8) { |
| 70 | case 0x05: /* balr */ |
| 71 | case 0x0d: /* basr */ |
| 72 | fixup = FIXUP_RETURN_REGISTER; |
| 73 | /* if r2 = 0, no branch will be taken */ |
| 74 | if ((insn[0] & 0x0f) == 0) |
| 75 | fixup |= FIXUP_BRANCH_NOT_TAKEN; |
| 76 | break; |
| 77 | case 0x06: /* bctr */ |
| 78 | case 0x07: /* bcr */ |
| 79 | fixup = FIXUP_BRANCH_NOT_TAKEN; |
| 80 | break; |
| 81 | case 0x45: /* bal */ |
| 82 | case 0x4d: /* bas */ |
| 83 | fixup = FIXUP_RETURN_REGISTER; |
| 84 | break; |
| 85 | case 0x47: /* bc */ |
| 86 | case 0x46: /* bct */ |
| 87 | case 0x86: /* bxh */ |
| 88 | case 0x87: /* bxle */ |
| 89 | fixup = FIXUP_BRANCH_NOT_TAKEN; |
| 90 | break; |
| 91 | case 0x82: /* lpsw */ |
| 92 | fixup = FIXUP_NOT_REQUIRED; |
| 93 | break; |
| 94 | case 0xb2: /* lpswe */ |
| 95 | if ((insn[0] & 0xff) == 0xb2) |
| 96 | fixup = FIXUP_NOT_REQUIRED; |
| 97 | break; |
| 98 | case 0xa7: /* bras */ |
| 99 | if ((insn[0] & 0x0f) == 0x05) |
| 100 | fixup |= FIXUP_RETURN_REGISTER; |
| 101 | break; |
| 102 | case 0xc0: |
| 103 | if ((insn[0] & 0x0f) == 0x00 || /* larl */ |
| 104 | (insn[0] & 0x0f) == 0x05) /* brasl */ |
| 105 | fixup |= FIXUP_RETURN_REGISTER; |
| 106 | break; |
| 107 | case 0xeb: |
| 108 | switch (insn[2] & 0xff) { |
| 109 | case 0x44: /* bxhg */ |
| 110 | case 0x45: /* bxleg */ |
| 111 | fixup = FIXUP_BRANCH_NOT_TAKEN; |
| 112 | break; |
| 113 | } |
| 114 | break; |
| 115 | case 0xe3: /* bctg */ |
| 116 | if ((insn[2] & 0xff) == 0x46) |
| 117 | fixup = FIXUP_BRANCH_NOT_TAKEN; |
| 118 | break; |
| 119 | case 0xec: |
| 120 | switch (insn[2] & 0xff) { |
| 121 | case 0xe5: /* clgrb */ |
| 122 | case 0xe6: /* cgrb */ |
| 123 | case 0xf6: /* crb */ |
| 124 | case 0xf7: /* clrb */ |
| 125 | case 0xfc: /* cgib */ |
| 126 | case 0xfd: /* cglib */ |
| 127 | case 0xfe: /* cib */ |
| 128 | case 0xff: /* clib */ |
| 129 | fixup = FIXUP_BRANCH_NOT_TAKEN; |
| 130 | break; |
| 131 | } |
| 132 | break; |
| 133 | } |
| 134 | return fixup; |
| 135 | } |
| 136 | |
| 137 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
| 138 | { |
| 139 | if ((unsigned long) p->addr & 0x01) |
| 140 | return -EINVAL; |
| 141 | |
| 142 | /* Make sure the probe isn't going on a difficult instruction */ |
| 143 | if (is_prohibited_opcode(p->addr)) |
| 144 | return -EINVAL; |
| 145 | |
| 146 | p->opcode = *p->addr; |
| 147 | memcpy(p->ainsn.insn, p->addr, ((p->opcode >> 14) + 3) & -2); |
| 148 | |
| 149 | return 0; |
| 150 | } |
| 151 | |
| 152 | struct ins_replace_args { |
| 153 | kprobe_opcode_t *ptr; |
| 154 | kprobe_opcode_t opcode; |
| 155 | }; |
| 156 | |
| 157 | static int __kprobes swap_instruction(void *aref) |
| 158 | { |
| 159 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 160 | unsigned long status = kcb->kprobe_status; |
| 161 | struct ins_replace_args *args = aref; |
| 162 | |
| 163 | kcb->kprobe_status = KPROBE_SWAP_INST; |
| 164 | probe_kernel_write(args->ptr, &args->opcode, sizeof(args->opcode)); |
| 165 | kcb->kprobe_status = status; |
| 166 | return 0; |
| 167 | } |
| 168 | |
| 169 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
| 170 | { |
| 171 | struct ins_replace_args args; |
| 172 | |
| 173 | args.ptr = p->addr; |
| 174 | args.opcode = BREAKPOINT_INSTRUCTION; |
| 175 | stop_machine(swap_instruction, &args, NULL); |
| 176 | } |
| 177 | |
| 178 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
| 179 | { |
| 180 | struct ins_replace_args args; |
| 181 | |
| 182 | args.ptr = p->addr; |
| 183 | args.opcode = p->opcode; |
| 184 | stop_machine(swap_instruction, &args, NULL); |
| 185 | } |
| 186 | |
| 187 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
| 188 | { |
| 189 | } |
| 190 | |
| 191 | static void __kprobes enable_singlestep(struct kprobe_ctlblk *kcb, |
| 192 | struct pt_regs *regs, |
| 193 | unsigned long ip) |
| 194 | { |
| 195 | struct per_regs per_kprobe; |
| 196 | |
| 197 | /* Set up the PER control registers %cr9-%cr11 */ |
| 198 | per_kprobe.control = PER_EVENT_IFETCH; |
| 199 | per_kprobe.start = ip; |
| 200 | per_kprobe.end = ip; |
| 201 | |
| 202 | /* Save control regs and psw mask */ |
| 203 | __ctl_store(kcb->kprobe_saved_ctl, 9, 11); |
| 204 | kcb->kprobe_saved_imask = regs->psw.mask & |
| 205 | (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT); |
| 206 | |
| 207 | /* Set PER control regs, turns on single step for the given address */ |
| 208 | __ctl_load(per_kprobe, 9, 11); |
| 209 | regs->psw.mask |= PSW_MASK_PER; |
| 210 | regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT); |
| 211 | regs->psw.addr = ip | PSW_ADDR_AMODE; |
| 212 | } |
| 213 | |
| 214 | static void __kprobes disable_singlestep(struct kprobe_ctlblk *kcb, |
| 215 | struct pt_regs *regs, |
| 216 | unsigned long ip) |
| 217 | { |
| 218 | /* Restore control regs and psw mask, set new psw address */ |
| 219 | __ctl_load(kcb->kprobe_saved_ctl, 9, 11); |
| 220 | regs->psw.mask &= ~PSW_MASK_PER; |
| 221 | regs->psw.mask |= kcb->kprobe_saved_imask; |
| 222 | regs->psw.addr = ip | PSW_ADDR_AMODE; |
| 223 | } |
| 224 | |
| 225 | /* |
| 226 | * Activate a kprobe by storing its pointer to current_kprobe. The |
| 227 | * previous kprobe is stored in kcb->prev_kprobe. A stack of up to |
| 228 | * two kprobes can be active, see KPROBE_REENTER. |
| 229 | */ |
| 230 | static void __kprobes push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p) |
| 231 | { |
| 232 | kcb->prev_kprobe.kp = __get_cpu_var(current_kprobe); |
| 233 | kcb->prev_kprobe.status = kcb->kprobe_status; |
| 234 | __get_cpu_var(current_kprobe) = p; |
| 235 | } |
| 236 | |
| 237 | /* |
| 238 | * Deactivate a kprobe by backing up to the previous state. If the |
| 239 | * current state is KPROBE_REENTER prev_kprobe.kp will be non-NULL, |
| 240 | * for any other state prev_kprobe.kp will be NULL. |
| 241 | */ |
| 242 | static void __kprobes pop_kprobe(struct kprobe_ctlblk *kcb) |
| 243 | { |
| 244 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
| 245 | kcb->kprobe_status = kcb->prev_kprobe.status; |
| 246 | } |
| 247 | |
| 248 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
| 249 | struct pt_regs *regs) |
| 250 | { |
| 251 | ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14]; |
| 252 | |
| 253 | /* Replace the return addr with trampoline addr */ |
| 254 | regs->gprs[14] = (unsigned long) &kretprobe_trampoline; |
| 255 | } |
| 256 | |
| 257 | static void __kprobes kprobe_reenter_check(struct kprobe_ctlblk *kcb, |
| 258 | struct kprobe *p) |
| 259 | { |
| 260 | switch (kcb->kprobe_status) { |
| 261 | case KPROBE_HIT_SSDONE: |
| 262 | case KPROBE_HIT_ACTIVE: |
| 263 | kprobes_inc_nmissed_count(p); |
| 264 | break; |
| 265 | case KPROBE_HIT_SS: |
| 266 | case KPROBE_REENTER: |
| 267 | default: |
| 268 | /* |
| 269 | * A kprobe on the code path to single step an instruction |
| 270 | * is a BUG. The code path resides in the .kprobes.text |
| 271 | * section and is executed with interrupts disabled. |
| 272 | */ |
| 273 | printk(KERN_EMERG "Invalid kprobe detected at %p.\n", p->addr); |
| 274 | dump_kprobe(p); |
| 275 | BUG(); |
| 276 | } |
| 277 | } |
| 278 | |
| 279 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
| 280 | { |
| 281 | struct kprobe_ctlblk *kcb; |
| 282 | struct kprobe *p; |
| 283 | |
| 284 | /* |
| 285 | * We want to disable preemption for the entire duration of kprobe |
| 286 | * processing. That includes the calls to the pre/post handlers |
| 287 | * and single stepping the kprobe instruction. |
| 288 | */ |
| 289 | preempt_disable(); |
| 290 | kcb = get_kprobe_ctlblk(); |
| 291 | p = get_kprobe((void *)((regs->psw.addr & PSW_ADDR_INSN) - 2)); |
| 292 | |
| 293 | if (p) { |
| 294 | if (kprobe_running()) { |
| 295 | /* |
| 296 | * We have hit a kprobe while another is still |
| 297 | * active. This can happen in the pre and post |
| 298 | * handler. Single step the instruction of the |
| 299 | * new probe but do not call any handler function |
| 300 | * of this secondary kprobe. |
| 301 | * push_kprobe and pop_kprobe saves and restores |
| 302 | * the currently active kprobe. |
| 303 | */ |
| 304 | kprobe_reenter_check(kcb, p); |
| 305 | push_kprobe(kcb, p); |
| 306 | kcb->kprobe_status = KPROBE_REENTER; |
| 307 | } else { |
| 308 | /* |
| 309 | * If we have no pre-handler or it returned 0, we |
| 310 | * continue with single stepping. If we have a |
| 311 | * pre-handler and it returned non-zero, it prepped |
| 312 | * for calling the break_handler below on re-entry |
| 313 | * for jprobe processing, so get out doing nothing |
| 314 | * more here. |
| 315 | */ |
| 316 | push_kprobe(kcb, p); |
| 317 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| 318 | if (p->pre_handler && p->pre_handler(p, regs)) |
| 319 | return 1; |
| 320 | kcb->kprobe_status = KPROBE_HIT_SS; |
| 321 | } |
| 322 | enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn); |
| 323 | return 1; |
| 324 | } else if (kprobe_running()) { |
| 325 | p = __get_cpu_var(current_kprobe); |
| 326 | if (p->break_handler && p->break_handler(p, regs)) { |
| 327 | /* |
| 328 | * Continuation after the jprobe completed and |
| 329 | * caused the jprobe_return trap. The jprobe |
| 330 | * break_handler "returns" to the original |
| 331 | * function that still has the kprobe breakpoint |
| 332 | * installed. We continue with single stepping. |
| 333 | */ |
| 334 | kcb->kprobe_status = KPROBE_HIT_SS; |
| 335 | enable_singlestep(kcb, regs, |
| 336 | (unsigned long) p->ainsn.insn); |
| 337 | return 1; |
| 338 | } /* else: |
| 339 | * No kprobe at this address and the current kprobe |
| 340 | * has no break handler (no jprobe!). The kernel just |
| 341 | * exploded, let the standard trap handler pick up the |
| 342 | * pieces. |
| 343 | */ |
| 344 | } /* else: |
| 345 | * No kprobe at this address and no active kprobe. The trap has |
| 346 | * not been caused by a kprobe breakpoint. The race of breakpoint |
| 347 | * vs. kprobe remove does not exist because on s390 as we use |
| 348 | * stop_machine to arm/disarm the breakpoints. |
| 349 | */ |
| 350 | preempt_enable_no_resched(); |
| 351 | return 0; |
| 352 | } |
| 353 | |
| 354 | /* |
| 355 | * Function return probe trampoline: |
| 356 | * - init_kprobes() establishes a probepoint here |
| 357 | * - When the probed function returns, this probe |
| 358 | * causes the handlers to fire |
| 359 | */ |
| 360 | static void __used kretprobe_trampoline_holder(void) |
| 361 | { |
| 362 | asm volatile(".global kretprobe_trampoline\n" |
| 363 | "kretprobe_trampoline: bcr 0,0\n"); |
| 364 | } |
| 365 | |
| 366 | /* |
| 367 | * Called when the probe at kretprobe trampoline is hit |
| 368 | */ |
| 369 | static int __kprobes trampoline_probe_handler(struct kprobe *p, |
| 370 | struct pt_regs *regs) |
| 371 | { |
| 372 | struct kretprobe_instance *ri; |
| 373 | struct hlist_head *head, empty_rp; |
| 374 | struct hlist_node *tmp; |
| 375 | unsigned long flags, orig_ret_address; |
| 376 | unsigned long trampoline_address; |
| 377 | kprobe_opcode_t *correct_ret_addr; |
| 378 | |
| 379 | INIT_HLIST_HEAD(&empty_rp); |
| 380 | kretprobe_hash_lock(current, &head, &flags); |
| 381 | |
| 382 | /* |
| 383 | * It is possible to have multiple instances associated with a given |
| 384 | * task either because an multiple functions in the call path |
| 385 | * have a return probe installed on them, and/or more than one return |
| 386 | * return probe was registered for a target function. |
| 387 | * |
| 388 | * We can handle this because: |
| 389 | * - instances are always inserted at the head of the list |
| 390 | * - when multiple return probes are registered for the same |
| 391 | * function, the first instance's ret_addr will point to the |
| 392 | * real return address, and all the rest will point to |
| 393 | * kretprobe_trampoline |
| 394 | */ |
| 395 | ri = NULL; |
| 396 | orig_ret_address = 0; |
| 397 | correct_ret_addr = NULL; |
| 398 | trampoline_address = (unsigned long) &kretprobe_trampoline; |
| 399 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
| 400 | if (ri->task != current) |
| 401 | /* another task is sharing our hash bucket */ |
| 402 | continue; |
| 403 | |
| 404 | orig_ret_address = (unsigned long) ri->ret_addr; |
| 405 | |
| 406 | if (orig_ret_address != trampoline_address) |
| 407 | /* |
| 408 | * This is the real return address. Any other |
| 409 | * instances associated with this task are for |
| 410 | * other calls deeper on the call stack |
| 411 | */ |
| 412 | break; |
| 413 | } |
| 414 | |
| 415 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
| 416 | |
| 417 | correct_ret_addr = ri->ret_addr; |
| 418 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
| 419 | if (ri->task != current) |
| 420 | /* another task is sharing our hash bucket */ |
| 421 | continue; |
| 422 | |
| 423 | orig_ret_address = (unsigned long) ri->ret_addr; |
| 424 | |
| 425 | if (ri->rp && ri->rp->handler) { |
| 426 | ri->ret_addr = correct_ret_addr; |
| 427 | ri->rp->handler(ri, regs); |
| 428 | } |
| 429 | |
| 430 | recycle_rp_inst(ri, &empty_rp); |
| 431 | |
| 432 | if (orig_ret_address != trampoline_address) |
| 433 | /* |
| 434 | * This is the real return address. Any other |
| 435 | * instances associated with this task are for |
| 436 | * other calls deeper on the call stack |
| 437 | */ |
| 438 | break; |
| 439 | } |
| 440 | |
| 441 | regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE; |
| 442 | |
| 443 | pop_kprobe(get_kprobe_ctlblk()); |
| 444 | kretprobe_hash_unlock(current, &flags); |
| 445 | preempt_enable_no_resched(); |
| 446 | |
| 447 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
| 448 | hlist_del(&ri->hlist); |
| 449 | kfree(ri); |
| 450 | } |
| 451 | /* |
| 452 | * By returning a non-zero value, we are telling |
| 453 | * kprobe_handler() that we don't want the post_handler |
| 454 | * to run (and have re-enabled preemption) |
| 455 | */ |
| 456 | return 1; |
| 457 | } |
| 458 | |
| 459 | /* |
| 460 | * Called after single-stepping. p->addr is the address of the |
| 461 | * instruction whose first byte has been replaced by the "breakpoint" |
| 462 | * instruction. To avoid the SMP problems that can occur when we |
| 463 | * temporarily put back the original opcode to single-step, we |
| 464 | * single-stepped a copy of the instruction. The address of this |
| 465 | * copy is p->ainsn.insn. |
| 466 | */ |
| 467 | static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) |
| 468 | { |
| 469 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 470 | unsigned long ip = regs->psw.addr & PSW_ADDR_INSN; |
| 471 | int fixup = get_fixup_type(p->ainsn.insn); |
| 472 | |
| 473 | if (fixup & FIXUP_PSW_NORMAL) |
| 474 | ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn; |
| 475 | |
| 476 | if (fixup & FIXUP_BRANCH_NOT_TAKEN) { |
| 477 | int ilen = ((p->ainsn.insn[0] >> 14) + 3) & -2; |
| 478 | if (ip - (unsigned long) p->ainsn.insn == ilen) |
| 479 | ip = (unsigned long) p->addr + ilen; |
| 480 | } |
| 481 | |
| 482 | if (fixup & FIXUP_RETURN_REGISTER) { |
| 483 | int reg = (p->ainsn.insn[0] & 0xf0) >> 4; |
| 484 | regs->gprs[reg] += (unsigned long) p->addr - |
| 485 | (unsigned long) p->ainsn.insn; |
| 486 | } |
| 487 | |
| 488 | disable_singlestep(kcb, regs, ip); |
| 489 | } |
| 490 | |
| 491 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) |
| 492 | { |
| 493 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 494 | struct kprobe *p = kprobe_running(); |
| 495 | |
| 496 | if (!p) |
| 497 | return 0; |
| 498 | |
| 499 | if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) { |
| 500 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 501 | p->post_handler(p, regs, 0); |
| 502 | } |
| 503 | |
| 504 | resume_execution(p, regs); |
| 505 | pop_kprobe(kcb); |
| 506 | preempt_enable_no_resched(); |
| 507 | |
| 508 | /* |
| 509 | * if somebody else is singlestepping across a probe point, psw mask |
| 510 | * will have PER set, in which case, continue the remaining processing |
| 511 | * of do_single_step, as if this is not a probe hit. |
| 512 | */ |
| 513 | if (regs->psw.mask & PSW_MASK_PER) |
| 514 | return 0; |
| 515 | |
| 516 | return 1; |
| 517 | } |
| 518 | |
| 519 | static int __kprobes kprobe_trap_handler(struct pt_regs *regs, int trapnr) |
| 520 | { |
| 521 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 522 | struct kprobe *p = kprobe_running(); |
| 523 | const struct exception_table_entry *entry; |
| 524 | |
| 525 | switch(kcb->kprobe_status) { |
| 526 | case KPROBE_SWAP_INST: |
| 527 | /* We are here because the instruction replacement failed */ |
| 528 | return 0; |
| 529 | case KPROBE_HIT_SS: |
| 530 | case KPROBE_REENTER: |
| 531 | /* |
| 532 | * We are here because the instruction being single |
| 533 | * stepped caused a page fault. We reset the current |
| 534 | * kprobe and the nip points back to the probe address |
| 535 | * and allow the page fault handler to continue as a |
| 536 | * normal page fault. |
| 537 | */ |
| 538 | disable_singlestep(kcb, regs, (unsigned long) p->addr); |
| 539 | pop_kprobe(kcb); |
| 540 | preempt_enable_no_resched(); |
| 541 | break; |
| 542 | case KPROBE_HIT_ACTIVE: |
| 543 | case KPROBE_HIT_SSDONE: |
| 544 | /* |
| 545 | * We increment the nmissed count for accounting, |
| 546 | * we can also use npre/npostfault count for accouting |
| 547 | * these specific fault cases. |
| 548 | */ |
| 549 | kprobes_inc_nmissed_count(p); |
| 550 | |
| 551 | /* |
| 552 | * We come here because instructions in the pre/post |
| 553 | * handler caused the page_fault, this could happen |
| 554 | * if handler tries to access user space by |
| 555 | * copy_from_user(), get_user() etc. Let the |
| 556 | * user-specified handler try to fix it first. |
| 557 | */ |
| 558 | if (p->fault_handler && p->fault_handler(p, regs, trapnr)) |
| 559 | return 1; |
| 560 | |
| 561 | /* |
| 562 | * In case the user-specified fault handler returned |
| 563 | * zero, try to fix up. |
| 564 | */ |
| 565 | entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN); |
| 566 | if (entry) { |
| 567 | regs->psw.addr = extable_fixup(entry) | PSW_ADDR_AMODE; |
| 568 | return 1; |
| 569 | } |
| 570 | |
| 571 | /* |
| 572 | * fixup_exception() could not handle it, |
| 573 | * Let do_page_fault() fix it. |
| 574 | */ |
| 575 | break; |
| 576 | default: |
| 577 | break; |
| 578 | } |
| 579 | return 0; |
| 580 | } |
| 581 | |
| 582 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
| 583 | { |
| 584 | int ret; |
| 585 | |
| 586 | if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) |
| 587 | local_irq_disable(); |
| 588 | ret = kprobe_trap_handler(regs, trapnr); |
| 589 | if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) |
| 590 | local_irq_restore(regs->psw.mask & ~PSW_MASK_PER); |
| 591 | return ret; |
| 592 | } |
| 593 | |
| 594 | /* |
| 595 | * Wrapper routine to for handling exceptions. |
| 596 | */ |
| 597 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
| 598 | unsigned long val, void *data) |
| 599 | { |
| 600 | struct die_args *args = (struct die_args *) data; |
| 601 | struct pt_regs *regs = args->regs; |
| 602 | int ret = NOTIFY_DONE; |
| 603 | |
| 604 | if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) |
| 605 | local_irq_disable(); |
| 606 | |
| 607 | switch (val) { |
| 608 | case DIE_BPT: |
| 609 | if (kprobe_handler(regs)) |
| 610 | ret = NOTIFY_STOP; |
| 611 | break; |
| 612 | case DIE_SSTEP: |
| 613 | if (post_kprobe_handler(regs)) |
| 614 | ret = NOTIFY_STOP; |
| 615 | break; |
| 616 | case DIE_TRAP: |
| 617 | if (!preemptible() && kprobe_running() && |
| 618 | kprobe_trap_handler(regs, args->trapnr)) |
| 619 | ret = NOTIFY_STOP; |
| 620 | break; |
| 621 | default: |
| 622 | break; |
| 623 | } |
| 624 | |
| 625 | if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) |
| 626 | local_irq_restore(regs->psw.mask & ~PSW_MASK_PER); |
| 627 | |
| 628 | return ret; |
| 629 | } |
| 630 | |
| 631 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
| 632 | { |
| 633 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 634 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 635 | unsigned long stack; |
| 636 | |
| 637 | memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs)); |
| 638 | |
| 639 | /* setup return addr to the jprobe handler routine */ |
| 640 | regs->psw.addr = (unsigned long) jp->entry | PSW_ADDR_AMODE; |
| 641 | regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT); |
| 642 | |
| 643 | /* r15 is the stack pointer */ |
| 644 | stack = (unsigned long) regs->gprs[15]; |
| 645 | |
| 646 | memcpy(kcb->jprobes_stack, (void *) stack, MIN_STACK_SIZE(stack)); |
| 647 | return 1; |
| 648 | } |
| 649 | |
| 650 | void __kprobes jprobe_return(void) |
| 651 | { |
| 652 | asm volatile(".word 0x0002"); |
| 653 | } |
| 654 | |
| 655 | static void __used __kprobes jprobe_return_end(void) |
| 656 | { |
| 657 | asm volatile("bcr 0,0"); |
| 658 | } |
| 659 | |
| 660 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
| 661 | { |
| 662 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 663 | unsigned long stack; |
| 664 | |
| 665 | stack = (unsigned long) kcb->jprobe_saved_regs.gprs[15]; |
| 666 | |
| 667 | /* Put the regs back */ |
| 668 | memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); |
| 669 | /* put the stack back */ |
| 670 | memcpy((void *) stack, kcb->jprobes_stack, MIN_STACK_SIZE(stack)); |
| 671 | preempt_enable_no_resched(); |
| 672 | return 1; |
| 673 | } |
| 674 | |
| 675 | static struct kprobe trampoline = { |
| 676 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, |
| 677 | .pre_handler = trampoline_probe_handler |
| 678 | }; |
| 679 | |
| 680 | int __init arch_init_kprobes(void) |
| 681 | { |
| 682 | return register_kprobe(&trampoline); |
| 683 | } |
| 684 | |
| 685 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
| 686 | { |
| 687 | return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline; |
| 688 | } |