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 <linux/module.h> 30 #include <linux/slab.h> 31 #include <linux/hardirq.h> 32 #include <linux/ftrace.h> 33 #include <asm/cacheflush.h> 34 #include <asm/sections.h> 35 #include <asm/dis.h> 36 37 DEFINE_PER_CPU(struct kprobe *, current_kprobe); 38 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); 39 40 struct kretprobe_blackpoint kretprobe_blacklist[] = { }; 41 42 DEFINE_INSN_CACHE_OPS(dmainsn); 43 44 static void *alloc_dmainsn_page(void) 45 { 46 return (void *)__get_free_page(GFP_KERNEL | GFP_DMA); 47 } 48 49 static void free_dmainsn_page(void *page) 50 { 51 free_page((unsigned long)page); 52 } 53 54 struct kprobe_insn_cache kprobe_dmainsn_slots = { 55 .mutex = __MUTEX_INITIALIZER(kprobe_dmainsn_slots.mutex), 56 .alloc = alloc_dmainsn_page, 57 .free = free_dmainsn_page, 58 .pages = LIST_HEAD_INIT(kprobe_dmainsn_slots.pages), 59 .insn_size = MAX_INSN_SIZE, 60 }; 61 62 static void copy_instruction(struct kprobe *p) 63 { 64 unsigned long ip = (unsigned long) p->addr; 65 s64 disp, new_disp; 66 u64 addr, new_addr; 67 68 if (ftrace_location(ip) == ip) { 69 /* 70 * If kprobes patches the instruction that is morphed by 71 * ftrace make sure that kprobes always sees the branch 72 * "jg .+24" that skips the mcount block or the "brcl 0,0" 73 * in case of hotpatch. 74 */ 75 ftrace_generate_nop_insn((struct ftrace_insn *)p->ainsn.insn); 76 p->ainsn.is_ftrace_insn = 1; 77 } else 78 memcpy(p->ainsn.insn, p->addr, insn_length(*p->addr >> 8)); 79 p->opcode = p->ainsn.insn[0]; 80 if (!probe_is_insn_relative_long(p->ainsn.insn)) 81 return; 82 /* 83 * For pc-relative instructions in RIL-b or RIL-c format patch the 84 * RI2 displacement field. We have already made sure that the insn 85 * slot for the patched instruction is within the same 2GB area 86 * as the original instruction (either kernel image or module area). 87 * Therefore the new displacement will always fit. 88 */ 89 disp = *(s32 *)&p->ainsn.insn[1]; 90 addr = (u64)(unsigned long)p->addr; 91 new_addr = (u64)(unsigned long)p->ainsn.insn; 92 new_disp = ((addr + (disp * 2)) - new_addr) / 2; 93 *(s32 *)&p->ainsn.insn[1] = new_disp; 94 } 95 NOKPROBE_SYMBOL(copy_instruction); 96 97 static inline int is_kernel_addr(void *addr) 98 { 99 return addr < (void *)_end; 100 } 101 102 static int s390_get_insn_slot(struct kprobe *p) 103 { 104 /* 105 * Get an insn slot that is within the same 2GB area like the original 106 * instruction. That way instructions with a 32bit signed displacement 107 * field can be patched and executed within the insn slot. 108 */ 109 p->ainsn.insn = NULL; 110 if (is_kernel_addr(p->addr)) 111 p->ainsn.insn = get_dmainsn_slot(); 112 else if (is_module_addr(p->addr)) 113 p->ainsn.insn = get_insn_slot(); 114 return p->ainsn.insn ? 0 : -ENOMEM; 115 } 116 NOKPROBE_SYMBOL(s390_get_insn_slot); 117 118 static void s390_free_insn_slot(struct kprobe *p) 119 { 120 if (!p->ainsn.insn) 121 return; 122 if (is_kernel_addr(p->addr)) 123 free_dmainsn_slot(p->ainsn.insn, 0); 124 else 125 free_insn_slot(p->ainsn.insn, 0); 126 p->ainsn.insn = NULL; 127 } 128 NOKPROBE_SYMBOL(s390_free_insn_slot); 129 130 int arch_prepare_kprobe(struct kprobe *p) 131 { 132 if ((unsigned long) p->addr & 0x01) 133 return -EINVAL; 134 /* Make sure the probe isn't going on a difficult instruction */ 135 if (probe_is_prohibited_opcode(p->addr)) 136 return -EINVAL; 137 if (s390_get_insn_slot(p)) 138 return -ENOMEM; 139 copy_instruction(p); 140 return 0; 141 } 142 NOKPROBE_SYMBOL(arch_prepare_kprobe); 143 144 int arch_check_ftrace_location(struct kprobe *p) 145 { 146 return 0; 147 } 148 149 struct swap_insn_args { 150 struct kprobe *p; 151 unsigned int arm_kprobe : 1; 152 }; 153 154 static int swap_instruction(void *data) 155 { 156 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); 157 unsigned long status = kcb->kprobe_status; 158 struct swap_insn_args *args = data; 159 struct ftrace_insn new_insn, *insn; 160 struct kprobe *p = args->p; 161 size_t len; 162 163 new_insn.opc = args->arm_kprobe ? BREAKPOINT_INSTRUCTION : p->opcode; 164 len = sizeof(new_insn.opc); 165 if (!p->ainsn.is_ftrace_insn) 166 goto skip_ftrace; 167 len = sizeof(new_insn); 168 insn = (struct ftrace_insn *) p->addr; 169 if (args->arm_kprobe) { 170 if (is_ftrace_nop(insn)) 171 new_insn.disp = KPROBE_ON_FTRACE_NOP; 172 else 173 new_insn.disp = KPROBE_ON_FTRACE_CALL; 174 } else { 175 ftrace_generate_call_insn(&new_insn, (unsigned long)p->addr); 176 if (insn->disp == KPROBE_ON_FTRACE_NOP) 177 ftrace_generate_nop_insn(&new_insn); 178 } 179 skip_ftrace: 180 kcb->kprobe_status = KPROBE_SWAP_INST; 181 s390_kernel_write(p->addr, &new_insn, len); 182 kcb->kprobe_status = status; 183 return 0; 184 } 185 NOKPROBE_SYMBOL(swap_instruction); 186 187 void arch_arm_kprobe(struct kprobe *p) 188 { 189 struct swap_insn_args args = {.p = p, .arm_kprobe = 1}; 190 191 stop_machine(swap_instruction, &args, NULL); 192 } 193 NOKPROBE_SYMBOL(arch_arm_kprobe); 194 195 void arch_disarm_kprobe(struct kprobe *p) 196 { 197 struct swap_insn_args args = {.p = p, .arm_kprobe = 0}; 198 199 stop_machine(swap_instruction, &args, NULL); 200 } 201 NOKPROBE_SYMBOL(arch_disarm_kprobe); 202 203 void arch_remove_kprobe(struct kprobe *p) 204 { 205 s390_free_insn_slot(p); 206 } 207 NOKPROBE_SYMBOL(arch_remove_kprobe); 208 209 static void enable_singlestep(struct kprobe_ctlblk *kcb, 210 struct pt_regs *regs, 211 unsigned long ip) 212 { 213 struct per_regs per_kprobe; 214 215 /* Set up the PER control registers %cr9-%cr11 */ 216 per_kprobe.control = PER_EVENT_IFETCH; 217 per_kprobe.start = ip; 218 per_kprobe.end = ip; 219 220 /* Save control regs and psw mask */ 221 __ctl_store(kcb->kprobe_saved_ctl, 9, 11); 222 kcb->kprobe_saved_imask = regs->psw.mask & 223 (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT); 224 225 /* Set PER control regs, turns on single step for the given address */ 226 __ctl_load(per_kprobe, 9, 11); 227 regs->psw.mask |= PSW_MASK_PER; 228 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT); 229 regs->psw.addr = ip | PSW_ADDR_AMODE; 230 } 231 NOKPROBE_SYMBOL(enable_singlestep); 232 233 static void disable_singlestep(struct kprobe_ctlblk *kcb, 234 struct pt_regs *regs, 235 unsigned long ip) 236 { 237 /* Restore control regs and psw mask, set new psw address */ 238 __ctl_load(kcb->kprobe_saved_ctl, 9, 11); 239 regs->psw.mask &= ~PSW_MASK_PER; 240 regs->psw.mask |= kcb->kprobe_saved_imask; 241 regs->psw.addr = ip | PSW_ADDR_AMODE; 242 } 243 NOKPROBE_SYMBOL(disable_singlestep); 244 245 /* 246 * Activate a kprobe by storing its pointer to current_kprobe. The 247 * previous kprobe is stored in kcb->prev_kprobe. A stack of up to 248 * two kprobes can be active, see KPROBE_REENTER. 249 */ 250 static void push_kprobe(struct kprobe_ctlblk *kcb, struct kprobe *p) 251 { 252 kcb->prev_kprobe.kp = __this_cpu_read(current_kprobe); 253 kcb->prev_kprobe.status = kcb->kprobe_status; 254 __this_cpu_write(current_kprobe, p); 255 } 256 NOKPROBE_SYMBOL(push_kprobe); 257 258 /* 259 * Deactivate a kprobe by backing up to the previous state. If the 260 * current state is KPROBE_REENTER prev_kprobe.kp will be non-NULL, 261 * for any other state prev_kprobe.kp will be NULL. 262 */ 263 static void pop_kprobe(struct kprobe_ctlblk *kcb) 264 { 265 __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); 266 kcb->kprobe_status = kcb->prev_kprobe.status; 267 } 268 NOKPROBE_SYMBOL(pop_kprobe); 269 270 void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) 271 { 272 ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14]; 273 274 /* Replace the return addr with trampoline addr */ 275 regs->gprs[14] = (unsigned long) &kretprobe_trampoline; 276 } 277 NOKPROBE_SYMBOL(arch_prepare_kretprobe); 278 279 static void kprobe_reenter_check(struct kprobe_ctlblk *kcb, struct kprobe *p) 280 { 281 switch (kcb->kprobe_status) { 282 case KPROBE_HIT_SSDONE: 283 case KPROBE_HIT_ACTIVE: 284 kprobes_inc_nmissed_count(p); 285 break; 286 case KPROBE_HIT_SS: 287 case KPROBE_REENTER: 288 default: 289 /* 290 * A kprobe on the code path to single step an instruction 291 * is a BUG. The code path resides in the .kprobes.text 292 * section and is executed with interrupts disabled. 293 */ 294 printk(KERN_EMERG "Invalid kprobe detected at %p.\n", p->addr); 295 dump_kprobe(p); 296 BUG(); 297 } 298 } 299 NOKPROBE_SYMBOL(kprobe_reenter_check); 300 301 static int kprobe_handler(struct pt_regs *regs) 302 { 303 struct kprobe_ctlblk *kcb; 304 struct kprobe *p; 305 306 /* 307 * We want to disable preemption for the entire duration of kprobe 308 * processing. That includes the calls to the pre/post handlers 309 * and single stepping the kprobe instruction. 310 */ 311 preempt_disable(); 312 kcb = get_kprobe_ctlblk(); 313 p = get_kprobe((void *)((regs->psw.addr & PSW_ADDR_INSN) - 2)); 314 315 if (p) { 316 if (kprobe_running()) { 317 /* 318 * We have hit a kprobe while another is still 319 * active. This can happen in the pre and post 320 * handler. Single step the instruction of the 321 * new probe but do not call any handler function 322 * of this secondary kprobe. 323 * push_kprobe and pop_kprobe saves and restores 324 * the currently active kprobe. 325 */ 326 kprobe_reenter_check(kcb, p); 327 push_kprobe(kcb, p); 328 kcb->kprobe_status = KPROBE_REENTER; 329 } else { 330 /* 331 * If we have no pre-handler or it returned 0, we 332 * continue with single stepping. If we have a 333 * pre-handler and it returned non-zero, it prepped 334 * for calling the break_handler below on re-entry 335 * for jprobe processing, so get out doing nothing 336 * more here. 337 */ 338 push_kprobe(kcb, p); 339 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 340 if (p->pre_handler && p->pre_handler(p, regs)) 341 return 1; 342 kcb->kprobe_status = KPROBE_HIT_SS; 343 } 344 enable_singlestep(kcb, regs, (unsigned long) p->ainsn.insn); 345 return 1; 346 } else if (kprobe_running()) { 347 p = __this_cpu_read(current_kprobe); 348 if (p->break_handler && p->break_handler(p, regs)) { 349 /* 350 * Continuation after the jprobe completed and 351 * caused the jprobe_return trap. The jprobe 352 * break_handler "returns" to the original 353 * function that still has the kprobe breakpoint 354 * installed. We continue with single stepping. 355 */ 356 kcb->kprobe_status = KPROBE_HIT_SS; 357 enable_singlestep(kcb, regs, 358 (unsigned long) p->ainsn.insn); 359 return 1; 360 } /* else: 361 * No kprobe at this address and the current kprobe 362 * has no break handler (no jprobe!). The kernel just 363 * exploded, let the standard trap handler pick up the 364 * pieces. 365 */ 366 } /* else: 367 * No kprobe at this address and no active kprobe. The trap has 368 * not been caused by a kprobe breakpoint. The race of breakpoint 369 * vs. kprobe remove does not exist because on s390 as we use 370 * stop_machine to arm/disarm the breakpoints. 371 */ 372 preempt_enable_no_resched(); 373 return 0; 374 } 375 NOKPROBE_SYMBOL(kprobe_handler); 376 377 /* 378 * Function return probe trampoline: 379 * - init_kprobes() establishes a probepoint here 380 * - When the probed function returns, this probe 381 * causes the handlers to fire 382 */ 383 static void __used kretprobe_trampoline_holder(void) 384 { 385 asm volatile(".global kretprobe_trampoline\n" 386 "kretprobe_trampoline: bcr 0,0\n"); 387 } 388 389 /* 390 * Called when the probe at kretprobe trampoline is hit 391 */ 392 static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) 393 { 394 struct kretprobe_instance *ri; 395 struct hlist_head *head, empty_rp; 396 struct hlist_node *tmp; 397 unsigned long flags, orig_ret_address; 398 unsigned long trampoline_address; 399 kprobe_opcode_t *correct_ret_addr; 400 401 INIT_HLIST_HEAD(&empty_rp); 402 kretprobe_hash_lock(current, &head, &flags); 403 404 /* 405 * It is possible to have multiple instances associated with a given 406 * task either because an multiple functions in the call path 407 * have a return probe installed on them, and/or more than one return 408 * return probe was registered for a target function. 409 * 410 * We can handle this because: 411 * - instances are always inserted at the head of the list 412 * - when multiple return probes are registered for the same 413 * function, the first instance's ret_addr will point to the 414 * real return address, and all the rest will point to 415 * kretprobe_trampoline 416 */ 417 ri = NULL; 418 orig_ret_address = 0; 419 correct_ret_addr = NULL; 420 trampoline_address = (unsigned long) &kretprobe_trampoline; 421 hlist_for_each_entry_safe(ri, tmp, head, hlist) { 422 if (ri->task != current) 423 /* another task is sharing our hash bucket */ 424 continue; 425 426 orig_ret_address = (unsigned long) ri->ret_addr; 427 428 if (orig_ret_address != trampoline_address) 429 /* 430 * This is the real return address. Any other 431 * instances associated with this task are for 432 * other calls deeper on the call stack 433 */ 434 break; 435 } 436 437 kretprobe_assert(ri, orig_ret_address, trampoline_address); 438 439 correct_ret_addr = ri->ret_addr; 440 hlist_for_each_entry_safe(ri, tmp, head, hlist) { 441 if (ri->task != current) 442 /* another task is sharing our hash bucket */ 443 continue; 444 445 orig_ret_address = (unsigned long) ri->ret_addr; 446 447 if (ri->rp && ri->rp->handler) { 448 ri->ret_addr = correct_ret_addr; 449 ri->rp->handler(ri, regs); 450 } 451 452 recycle_rp_inst(ri, &empty_rp); 453 454 if (orig_ret_address != trampoline_address) 455 /* 456 * This is the real return address. Any other 457 * instances associated with this task are for 458 * other calls deeper on the call stack 459 */ 460 break; 461 } 462 463 regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE; 464 465 pop_kprobe(get_kprobe_ctlblk()); 466 kretprobe_hash_unlock(current, &flags); 467 preempt_enable_no_resched(); 468 469 hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { 470 hlist_del(&ri->hlist); 471 kfree(ri); 472 } 473 /* 474 * By returning a non-zero value, we are telling 475 * kprobe_handler() that we don't want the post_handler 476 * to run (and have re-enabled preemption) 477 */ 478 return 1; 479 } 480 NOKPROBE_SYMBOL(trampoline_probe_handler); 481 482 /* 483 * Called after single-stepping. p->addr is the address of the 484 * instruction whose first byte has been replaced by the "breakpoint" 485 * instruction. To avoid the SMP problems that can occur when we 486 * temporarily put back the original opcode to single-step, we 487 * single-stepped a copy of the instruction. The address of this 488 * copy is p->ainsn.insn. 489 */ 490 static void resume_execution(struct kprobe *p, struct pt_regs *regs) 491 { 492 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); 493 unsigned long ip = regs->psw.addr & PSW_ADDR_INSN; 494 int fixup = probe_get_fixup_type(p->ainsn.insn); 495 496 /* Check if the kprobes location is an enabled ftrace caller */ 497 if (p->ainsn.is_ftrace_insn) { 498 struct ftrace_insn *insn = (struct ftrace_insn *) p->addr; 499 struct ftrace_insn call_insn; 500 501 ftrace_generate_call_insn(&call_insn, (unsigned long) p->addr); 502 /* 503 * A kprobe on an enabled ftrace call site actually single 504 * stepped an unconditional branch (ftrace nop equivalent). 505 * Now we need to fixup things and pretend that a brasl r0,... 506 * was executed instead. 507 */ 508 if (insn->disp == KPROBE_ON_FTRACE_CALL) { 509 ip += call_insn.disp * 2 - MCOUNT_INSN_SIZE; 510 regs->gprs[0] = (unsigned long)p->addr + sizeof(*insn); 511 } 512 } 513 514 if (fixup & FIXUP_PSW_NORMAL) 515 ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn; 516 517 if (fixup & FIXUP_BRANCH_NOT_TAKEN) { 518 int ilen = insn_length(p->ainsn.insn[0] >> 8); 519 if (ip - (unsigned long) p->ainsn.insn == ilen) 520 ip = (unsigned long) p->addr + ilen; 521 } 522 523 if (fixup & FIXUP_RETURN_REGISTER) { 524 int reg = (p->ainsn.insn[0] & 0xf0) >> 4; 525 regs->gprs[reg] += (unsigned long) p->addr - 526 (unsigned long) p->ainsn.insn; 527 } 528 529 disable_singlestep(kcb, regs, ip); 530 } 531 NOKPROBE_SYMBOL(resume_execution); 532 533 static int post_kprobe_handler(struct pt_regs *regs) 534 { 535 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); 536 struct kprobe *p = kprobe_running(); 537 538 if (!p) 539 return 0; 540 541 if (kcb->kprobe_status != KPROBE_REENTER && p->post_handler) { 542 kcb->kprobe_status = KPROBE_HIT_SSDONE; 543 p->post_handler(p, regs, 0); 544 } 545 546 resume_execution(p, regs); 547 pop_kprobe(kcb); 548 preempt_enable_no_resched(); 549 550 /* 551 * if somebody else is singlestepping across a probe point, psw mask 552 * will have PER set, in which case, continue the remaining processing 553 * of do_single_step, as if this is not a probe hit. 554 */ 555 if (regs->psw.mask & PSW_MASK_PER) 556 return 0; 557 558 return 1; 559 } 560 NOKPROBE_SYMBOL(post_kprobe_handler); 561 562 static int kprobe_trap_handler(struct pt_regs *regs, int trapnr) 563 { 564 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); 565 struct kprobe *p = kprobe_running(); 566 const struct exception_table_entry *entry; 567 568 switch(kcb->kprobe_status) { 569 case KPROBE_SWAP_INST: 570 /* We are here because the instruction replacement failed */ 571 return 0; 572 case KPROBE_HIT_SS: 573 case KPROBE_REENTER: 574 /* 575 * We are here because the instruction being single 576 * stepped caused a page fault. We reset the current 577 * kprobe and the nip points back to the probe address 578 * and allow the page fault handler to continue as a 579 * normal page fault. 580 */ 581 disable_singlestep(kcb, regs, (unsigned long) p->addr); 582 pop_kprobe(kcb); 583 preempt_enable_no_resched(); 584 break; 585 case KPROBE_HIT_ACTIVE: 586 case KPROBE_HIT_SSDONE: 587 /* 588 * We increment the nmissed count for accounting, 589 * we can also use npre/npostfault count for accounting 590 * these specific fault cases. 591 */ 592 kprobes_inc_nmissed_count(p); 593 594 /* 595 * We come here because instructions in the pre/post 596 * handler caused the page_fault, this could happen 597 * if handler tries to access user space by 598 * copy_from_user(), get_user() etc. Let the 599 * user-specified handler try to fix it first. 600 */ 601 if (p->fault_handler && p->fault_handler(p, regs, trapnr)) 602 return 1; 603 604 /* 605 * In case the user-specified fault handler returned 606 * zero, try to fix up. 607 */ 608 entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN); 609 if (entry) { 610 regs->psw.addr = extable_fixup(entry) | PSW_ADDR_AMODE; 611 return 1; 612 } 613 614 /* 615 * fixup_exception() could not handle it, 616 * Let do_page_fault() fix it. 617 */ 618 break; 619 default: 620 break; 621 } 622 return 0; 623 } 624 NOKPROBE_SYMBOL(kprobe_trap_handler); 625 626 int kprobe_fault_handler(struct pt_regs *regs, int trapnr) 627 { 628 int ret; 629 630 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) 631 local_irq_disable(); 632 ret = kprobe_trap_handler(regs, trapnr); 633 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) 634 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER); 635 return ret; 636 } 637 NOKPROBE_SYMBOL(kprobe_fault_handler); 638 639 /* 640 * Wrapper routine to for handling exceptions. 641 */ 642 int kprobe_exceptions_notify(struct notifier_block *self, 643 unsigned long val, void *data) 644 { 645 struct die_args *args = (struct die_args *) data; 646 struct pt_regs *regs = args->regs; 647 int ret = NOTIFY_DONE; 648 649 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) 650 local_irq_disable(); 651 652 switch (val) { 653 case DIE_BPT: 654 if (kprobe_handler(regs)) 655 ret = NOTIFY_STOP; 656 break; 657 case DIE_SSTEP: 658 if (post_kprobe_handler(regs)) 659 ret = NOTIFY_STOP; 660 break; 661 case DIE_TRAP: 662 if (!preemptible() && kprobe_running() && 663 kprobe_trap_handler(regs, args->trapnr)) 664 ret = NOTIFY_STOP; 665 break; 666 default: 667 break; 668 } 669 670 if (regs->psw.mask & (PSW_MASK_IO | PSW_MASK_EXT)) 671 local_irq_restore(regs->psw.mask & ~PSW_MASK_PER); 672 673 return ret; 674 } 675 NOKPROBE_SYMBOL(kprobe_exceptions_notify); 676 677 int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) 678 { 679 struct jprobe *jp = container_of(p, struct jprobe, kp); 680 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); 681 unsigned long stack; 682 683 memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs)); 684 685 /* setup return addr to the jprobe handler routine */ 686 regs->psw.addr = (unsigned long) jp->entry | PSW_ADDR_AMODE; 687 regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT); 688 689 /* r15 is the stack pointer */ 690 stack = (unsigned long) regs->gprs[15]; 691 692 memcpy(kcb->jprobes_stack, (void *) stack, MIN_STACK_SIZE(stack)); 693 return 1; 694 } 695 NOKPROBE_SYMBOL(setjmp_pre_handler); 696 697 void jprobe_return(void) 698 { 699 asm volatile(".word 0x0002"); 700 } 701 NOKPROBE_SYMBOL(jprobe_return); 702 703 int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) 704 { 705 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); 706 unsigned long stack; 707 708 stack = (unsigned long) kcb->jprobe_saved_regs.gprs[15]; 709 710 /* Put the regs back */ 711 memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); 712 /* put the stack back */ 713 memcpy((void *) stack, kcb->jprobes_stack, MIN_STACK_SIZE(stack)); 714 preempt_enable_no_resched(); 715 return 1; 716 } 717 NOKPROBE_SYMBOL(longjmp_break_handler); 718 719 static struct kprobe trampoline = { 720 .addr = (kprobe_opcode_t *) &kretprobe_trampoline, 721 .pre_handler = trampoline_probe_handler 722 }; 723 724 int __init arch_init_kprobes(void) 725 { 726 return register_kprobe(&trampoline); 727 } 728 729 int arch_trampoline_kprobe(struct kprobe *p) 730 { 731 return p->addr == (kprobe_opcode_t *) &kretprobe_trampoline; 732 } 733 NOKPROBE_SYMBOL(arch_trampoline_kprobe); 734