Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 1 | /* |
| 2 | * arch/tile/kernel/kprobes.c |
| 3 | * Kprobes on TILE-Gx |
| 4 | * |
| 5 | * Some portions copied from the MIPS version. |
| 6 | * |
| 7 | * Copyright (C) IBM Corporation, 2002, 2004 |
| 8 | * Copyright 2006 Sony Corp. |
| 9 | * Copyright 2010 Cavium Networks |
| 10 | * |
| 11 | * Copyright 2012 Tilera Corporation. All Rights Reserved. |
| 12 | * |
| 13 | * This program is free software; you can redistribute it and/or |
| 14 | * modify it under the terms of the GNU General Public License |
| 15 | * as published by the Free Software Foundation, version 2. |
| 16 | * |
| 17 | * This program is distributed in the hope that it will be useful, but |
| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or |
| 20 | * NON INFRINGEMENT. See the GNU General Public License for |
| 21 | * more details. |
| 22 | */ |
| 23 | |
| 24 | #include <linux/kprobes.h> |
| 25 | #include <linux/kdebug.h> |
| 26 | #include <linux/module.h> |
| 27 | #include <linux/slab.h> |
| 28 | #include <linux/uaccess.h> |
| 29 | #include <asm/cacheflush.h> |
| 30 | |
| 31 | #include <arch/opcode.h> |
| 32 | |
| 33 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
| 34 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
| 35 | |
| 36 | tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE; |
| 37 | tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP; |
| 38 | |
| 39 | /* |
| 40 | * Check whether instruction is branch or jump, or if executing it |
| 41 | * has different results depending on where it is executed (e.g. lnk). |
| 42 | */ |
| 43 | static int __kprobes insn_has_control(kprobe_opcode_t insn) |
| 44 | { |
| 45 | if (get_Mode(insn) != 0) { /* Y-format bundle */ |
| 46 | if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 || |
| 47 | get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1) |
| 48 | return 0; |
| 49 | |
| 50 | switch (get_UnaryOpcodeExtension_Y1(insn)) { |
| 51 | case JALRP_UNARY_OPCODE_Y1: |
| 52 | case JALR_UNARY_OPCODE_Y1: |
| 53 | case JRP_UNARY_OPCODE_Y1: |
| 54 | case JR_UNARY_OPCODE_Y1: |
| 55 | case LNK_UNARY_OPCODE_Y1: |
| 56 | return 1; |
| 57 | default: |
| 58 | return 0; |
| 59 | } |
| 60 | } |
| 61 | |
| 62 | switch (get_Opcode_X1(insn)) { |
| 63 | case BRANCH_OPCODE_X1: /* branch instructions */ |
| 64 | case JUMP_OPCODE_X1: /* jump instructions: j and jal */ |
| 65 | return 1; |
| 66 | |
| 67 | case RRR_0_OPCODE_X1: /* other jump instructions */ |
| 68 | if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1) |
| 69 | return 0; |
| 70 | switch (get_UnaryOpcodeExtension_X1(insn)) { |
| 71 | case JALRP_UNARY_OPCODE_X1: |
| 72 | case JALR_UNARY_OPCODE_X1: |
| 73 | case JRP_UNARY_OPCODE_X1: |
| 74 | case JR_UNARY_OPCODE_X1: |
| 75 | case LNK_UNARY_OPCODE_X1: |
| 76 | return 1; |
| 77 | default: |
| 78 | return 0; |
| 79 | } |
| 80 | default: |
| 81 | return 0; |
| 82 | } |
| 83 | } |
| 84 | |
| 85 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
| 86 | { |
| 87 | unsigned long addr = (unsigned long)p->addr; |
| 88 | |
| 89 | if (addr & (sizeof(kprobe_opcode_t) - 1)) |
| 90 | return -EINVAL; |
| 91 | |
| 92 | if (insn_has_control(*p->addr)) { |
Joe Perches | f474367 | 2014-10-31 10:50:46 -0700 | [diff] [blame] | 93 | pr_notice("Kprobes for control instructions are not supported\n"); |
Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 94 | return -EINVAL; |
| 95 | } |
| 96 | |
| 97 | /* insn: must be on special executable page on tile. */ |
| 98 | p->ainsn.insn = get_insn_slot(); |
| 99 | if (!p->ainsn.insn) |
| 100 | return -ENOMEM; |
| 101 | |
| 102 | /* |
| 103 | * In the kprobe->ainsn.insn[] array we store the original |
| 104 | * instruction at index zero and a break trap instruction at |
| 105 | * index one. |
| 106 | */ |
| 107 | memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t)); |
| 108 | p->ainsn.insn[1] = breakpoint2_insn; |
| 109 | p->opcode = *p->addr; |
| 110 | |
| 111 | return 0; |
| 112 | } |
| 113 | |
| 114 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
| 115 | { |
| 116 | unsigned long addr_wr; |
| 117 | |
| 118 | /* Operate on writable kernel text mapping. */ |
Zhigang Lu | f419e6f | 2015-09-30 09:53:47 +0800 | [diff] [blame] | 119 | addr_wr = ktext_writable_addr(p->addr); |
Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 120 | |
| 121 | if (probe_kernel_write((void *)addr_wr, &breakpoint_insn, |
| 122 | sizeof(breakpoint_insn))) |
| 123 | pr_err("%s: failed to enable kprobe\n", __func__); |
| 124 | |
| 125 | smp_wmb(); |
| 126 | flush_insn_slot(p); |
| 127 | } |
| 128 | |
| 129 | void __kprobes arch_disarm_kprobe(struct kprobe *kp) |
| 130 | { |
| 131 | unsigned long addr_wr; |
| 132 | |
| 133 | /* Operate on writable kernel text mapping. */ |
Zhigang Lu | f419e6f | 2015-09-30 09:53:47 +0800 | [diff] [blame] | 134 | addr_wr = ktext_writable_addr(kp->addr); |
Tony Lu | 3fa17c3 | 2013-08-09 15:08:57 -0400 | [diff] [blame] | 135 | |
| 136 | if (probe_kernel_write((void *)addr_wr, &kp->opcode, |
| 137 | sizeof(kp->opcode))) |
| 138 | pr_err("%s: failed to enable kprobe\n", __func__); |
| 139 | |
| 140 | smp_wmb(); |
| 141 | flush_insn_slot(kp); |
| 142 | } |
| 143 | |
| 144 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
| 145 | { |
| 146 | if (p->ainsn.insn) { |
| 147 | free_insn_slot(p->ainsn.insn, 0); |
| 148 | p->ainsn.insn = NULL; |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
| 153 | { |
| 154 | kcb->prev_kprobe.kp = kprobe_running(); |
| 155 | kcb->prev_kprobe.status = kcb->kprobe_status; |
| 156 | kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc; |
| 157 | } |
| 158 | |
| 159 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
| 160 | { |
| 161 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
| 162 | kcb->kprobe_status = kcb->prev_kprobe.status; |
| 163 | kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc; |
| 164 | } |
| 165 | |
| 166 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
| 167 | struct kprobe_ctlblk *kcb) |
| 168 | { |
| 169 | __this_cpu_write(current_kprobe, p); |
| 170 | kcb->kprobe_saved_pc = regs->pc; |
| 171 | } |
| 172 | |
| 173 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
| 174 | { |
| 175 | /* Single step inline if the instruction is a break. */ |
| 176 | if (p->opcode == breakpoint_insn || |
| 177 | p->opcode == breakpoint2_insn) |
| 178 | regs->pc = (unsigned long)p->addr; |
| 179 | else |
| 180 | regs->pc = (unsigned long)&p->ainsn.insn[0]; |
| 181 | } |
| 182 | |
| 183 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
| 184 | { |
| 185 | struct kprobe *p; |
| 186 | int ret = 0; |
| 187 | kprobe_opcode_t *addr; |
| 188 | struct kprobe_ctlblk *kcb; |
| 189 | |
| 190 | addr = (kprobe_opcode_t *)regs->pc; |
| 191 | |
| 192 | /* |
| 193 | * We don't want to be preempted for the entire |
| 194 | * duration of kprobe processing. |
| 195 | */ |
| 196 | preempt_disable(); |
| 197 | kcb = get_kprobe_ctlblk(); |
| 198 | |
| 199 | /* Check we're not actually recursing. */ |
| 200 | if (kprobe_running()) { |
| 201 | p = get_kprobe(addr); |
| 202 | if (p) { |
| 203 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
| 204 | p->ainsn.insn[0] == breakpoint_insn) { |
| 205 | goto no_kprobe; |
| 206 | } |
| 207 | /* |
| 208 | * We have reentered the kprobe_handler(), since |
| 209 | * another probe was hit while within the handler. |
| 210 | * We here save the original kprobes variables and |
| 211 | * just single step on the instruction of the new probe |
| 212 | * without calling any user handlers. |
| 213 | */ |
| 214 | save_previous_kprobe(kcb); |
| 215 | set_current_kprobe(p, regs, kcb); |
| 216 | kprobes_inc_nmissed_count(p); |
| 217 | prepare_singlestep(p, regs); |
| 218 | kcb->kprobe_status = KPROBE_REENTER; |
| 219 | return 1; |
| 220 | } else { |
| 221 | if (*addr != breakpoint_insn) { |
| 222 | /* |
| 223 | * The breakpoint instruction was removed by |
| 224 | * another cpu right after we hit, no further |
| 225 | * handling of this interrupt is appropriate. |
| 226 | */ |
| 227 | ret = 1; |
| 228 | goto no_kprobe; |
| 229 | } |
| 230 | p = __this_cpu_read(current_kprobe); |
| 231 | if (p->break_handler && p->break_handler(p, regs)) |
| 232 | goto ss_probe; |
| 233 | } |
| 234 | goto no_kprobe; |
| 235 | } |
| 236 | |
| 237 | p = get_kprobe(addr); |
| 238 | if (!p) { |
| 239 | if (*addr != breakpoint_insn) { |
| 240 | /* |
| 241 | * The breakpoint instruction was removed right |
| 242 | * after we hit it. Another cpu has removed |
| 243 | * either a probepoint or a debugger breakpoint |
| 244 | * at this address. In either case, no further |
| 245 | * handling of this interrupt is appropriate. |
| 246 | */ |
| 247 | ret = 1; |
| 248 | } |
| 249 | /* Not one of ours: let kernel handle it. */ |
| 250 | goto no_kprobe; |
| 251 | } |
| 252 | |
| 253 | set_current_kprobe(p, regs, kcb); |
| 254 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| 255 | |
| 256 | if (p->pre_handler && p->pre_handler(p, regs)) { |
| 257 | /* Handler has already set things up, so skip ss setup. */ |
| 258 | return 1; |
| 259 | } |
| 260 | |
| 261 | ss_probe: |
| 262 | prepare_singlestep(p, regs); |
| 263 | kcb->kprobe_status = KPROBE_HIT_SS; |
| 264 | return 1; |
| 265 | |
| 266 | no_kprobe: |
| 267 | preempt_enable_no_resched(); |
| 268 | return ret; |
| 269 | } |
| 270 | |
| 271 | /* |
| 272 | * Called after single-stepping. p->addr is the address of the |
| 273 | * instruction that has been replaced by the breakpoint. To avoid the |
| 274 | * SMP problems that can occur when we temporarily put back the |
| 275 | * original opcode to single-step, we single-stepped a copy of the |
| 276 | * instruction. The address of this copy is p->ainsn.insn. |
| 277 | * |
| 278 | * This function prepares to return from the post-single-step |
| 279 | * breakpoint trap. |
| 280 | */ |
| 281 | static void __kprobes resume_execution(struct kprobe *p, |
| 282 | struct pt_regs *regs, |
| 283 | struct kprobe_ctlblk *kcb) |
| 284 | { |
| 285 | unsigned long orig_pc = kcb->kprobe_saved_pc; |
| 286 | regs->pc = orig_pc + 8; |
| 287 | } |
| 288 | |
| 289 | static inline int post_kprobe_handler(struct pt_regs *regs) |
| 290 | { |
| 291 | struct kprobe *cur = kprobe_running(); |
| 292 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 293 | |
| 294 | if (!cur) |
| 295 | return 0; |
| 296 | |
| 297 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
| 298 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 299 | cur->post_handler(cur, regs, 0); |
| 300 | } |
| 301 | |
| 302 | resume_execution(cur, regs, kcb); |
| 303 | |
| 304 | /* Restore back the original saved kprobes variables and continue. */ |
| 305 | if (kcb->kprobe_status == KPROBE_REENTER) { |
| 306 | restore_previous_kprobe(kcb); |
| 307 | goto out; |
| 308 | } |
| 309 | reset_current_kprobe(); |
| 310 | out: |
| 311 | preempt_enable_no_resched(); |
| 312 | |
| 313 | return 1; |
| 314 | } |
| 315 | |
| 316 | static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
| 317 | { |
| 318 | struct kprobe *cur = kprobe_running(); |
| 319 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 320 | |
| 321 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) |
| 322 | return 1; |
| 323 | |
| 324 | if (kcb->kprobe_status & KPROBE_HIT_SS) { |
| 325 | /* |
| 326 | * We are here because the instruction being single |
| 327 | * stepped caused a page fault. We reset the current |
| 328 | * kprobe and the ip points back to the probe address |
| 329 | * and allow the page fault handler to continue as a |
| 330 | * normal page fault. |
| 331 | */ |
| 332 | resume_execution(cur, regs, kcb); |
| 333 | reset_current_kprobe(); |
| 334 | preempt_enable_no_resched(); |
| 335 | } |
| 336 | return 0; |
| 337 | } |
| 338 | |
| 339 | /* |
| 340 | * Wrapper routine for handling exceptions. |
| 341 | */ |
| 342 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
| 343 | unsigned long val, void *data) |
| 344 | { |
| 345 | struct die_args *args = (struct die_args *)data; |
| 346 | int ret = NOTIFY_DONE; |
| 347 | |
| 348 | switch (val) { |
| 349 | case DIE_BREAK: |
| 350 | if (kprobe_handler(args->regs)) |
| 351 | ret = NOTIFY_STOP; |
| 352 | break; |
| 353 | case DIE_SSTEPBP: |
| 354 | if (post_kprobe_handler(args->regs)) |
| 355 | ret = NOTIFY_STOP; |
| 356 | break; |
| 357 | case DIE_PAGE_FAULT: |
| 358 | /* kprobe_running() needs smp_processor_id(). */ |
| 359 | preempt_disable(); |
| 360 | |
| 361 | if (kprobe_running() |
| 362 | && kprobe_fault_handler(args->regs, args->trapnr)) |
| 363 | ret = NOTIFY_STOP; |
| 364 | preempt_enable(); |
| 365 | break; |
| 366 | default: |
| 367 | break; |
| 368 | } |
| 369 | return ret; |
| 370 | } |
| 371 | |
| 372 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
| 373 | { |
| 374 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 375 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 376 | |
| 377 | kcb->jprobe_saved_regs = *regs; |
| 378 | kcb->jprobe_saved_sp = regs->sp; |
| 379 | |
| 380 | memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp, |
| 381 | MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); |
| 382 | |
| 383 | regs->pc = (unsigned long)(jp->entry); |
| 384 | |
| 385 | return 1; |
| 386 | } |
| 387 | |
| 388 | /* Defined in the inline asm below. */ |
| 389 | void jprobe_return_end(void); |
| 390 | |
| 391 | void __kprobes jprobe_return(void) |
| 392 | { |
| 393 | asm volatile( |
| 394 | "bpt\n\t" |
| 395 | ".globl jprobe_return_end\n" |
| 396 | "jprobe_return_end:\n"); |
| 397 | } |
| 398 | |
| 399 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
| 400 | { |
| 401 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 402 | |
| 403 | if (regs->pc >= (unsigned long)jprobe_return && |
| 404 | regs->pc <= (unsigned long)jprobe_return_end) { |
| 405 | *regs = kcb->jprobe_saved_regs; |
| 406 | memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack, |
| 407 | MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); |
| 408 | preempt_enable_no_resched(); |
| 409 | |
| 410 | return 1; |
| 411 | } |
| 412 | return 0; |
| 413 | } |
| 414 | |
| 415 | /* |
| 416 | * Function return probe trampoline: |
| 417 | * - init_kprobes() establishes a probepoint here |
| 418 | * - When the probed function returns, this probe causes the |
| 419 | * handlers to fire |
| 420 | */ |
| 421 | static void __used kretprobe_trampoline_holder(void) |
| 422 | { |
| 423 | asm volatile( |
| 424 | "nop\n\t" |
| 425 | ".global kretprobe_trampoline\n" |
| 426 | "kretprobe_trampoline:\n\t" |
| 427 | "nop\n\t" |
| 428 | : : : "memory"); |
| 429 | } |
| 430 | |
| 431 | void kretprobe_trampoline(void); |
| 432 | |
| 433 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
| 434 | struct pt_regs *regs) |
| 435 | { |
| 436 | ri->ret_addr = (kprobe_opcode_t *) regs->lr; |
| 437 | |
| 438 | /* Replace the return addr with trampoline addr */ |
| 439 | regs->lr = (unsigned long)kretprobe_trampoline; |
| 440 | } |
| 441 | |
| 442 | /* |
| 443 | * Called when the probe at kretprobe trampoline is hit. |
| 444 | */ |
| 445 | static int __kprobes trampoline_probe_handler(struct kprobe *p, |
| 446 | struct pt_regs *regs) |
| 447 | { |
| 448 | struct kretprobe_instance *ri = NULL; |
| 449 | struct hlist_head *head, empty_rp; |
| 450 | struct hlist_node *tmp; |
| 451 | unsigned long flags, orig_ret_address = 0; |
| 452 | unsigned long trampoline_address = (unsigned long)kretprobe_trampoline; |
| 453 | |
| 454 | INIT_HLIST_HEAD(&empty_rp); |
| 455 | kretprobe_hash_lock(current, &head, &flags); |
| 456 | |
| 457 | /* |
| 458 | * It is possible to have multiple instances associated with a given |
| 459 | * task either because multiple functions in the call path have |
| 460 | * a return probe installed on them, and/or more than one return |
| 461 | * return probe was registered for a target function. |
| 462 | * |
| 463 | * We can handle this because: |
| 464 | * - instances are always inserted at the head of the list |
| 465 | * - when multiple return probes are registered for the same |
| 466 | * function, the first instance's ret_addr will point to the |
| 467 | * real return address, and all the rest will point to |
| 468 | * kretprobe_trampoline |
| 469 | */ |
| 470 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
| 471 | if (ri->task != current) |
| 472 | /* another task is sharing our hash bucket */ |
| 473 | continue; |
| 474 | |
| 475 | if (ri->rp && ri->rp->handler) |
| 476 | ri->rp->handler(ri, regs); |
| 477 | |
| 478 | orig_ret_address = (unsigned long)ri->ret_addr; |
| 479 | recycle_rp_inst(ri, &empty_rp); |
| 480 | |
| 481 | if (orig_ret_address != trampoline_address) { |
| 482 | /* |
| 483 | * This is the real return address. Any other |
| 484 | * instances associated with this task are for |
| 485 | * other calls deeper on the call stack |
| 486 | */ |
| 487 | break; |
| 488 | } |
| 489 | } |
| 490 | |
| 491 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
| 492 | instruction_pointer(regs) = orig_ret_address; |
| 493 | |
| 494 | reset_current_kprobe(); |
| 495 | kretprobe_hash_unlock(current, &flags); |
| 496 | preempt_enable_no_resched(); |
| 497 | |
| 498 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
| 499 | hlist_del(&ri->hlist); |
| 500 | kfree(ri); |
| 501 | } |
| 502 | /* |
| 503 | * By returning a non-zero value, we are telling |
| 504 | * kprobe_handler() that we don't want the post_handler |
| 505 | * to run (and have re-enabled preemption) |
| 506 | */ |
| 507 | return 1; |
| 508 | } |
| 509 | |
| 510 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
| 511 | { |
| 512 | if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline) |
| 513 | return 1; |
| 514 | |
| 515 | return 0; |
| 516 | } |
| 517 | |
| 518 | static struct kprobe trampoline_p = { |
| 519 | .addr = (kprobe_opcode_t *)kretprobe_trampoline, |
| 520 | .pre_handler = trampoline_probe_handler |
| 521 | }; |
| 522 | |
| 523 | int __init arch_init_kprobes(void) |
| 524 | { |
| 525 | register_kprobe(&trampoline_p); |
| 526 | return 0; |
| 527 | } |