| 1 | /* |
| 2 | * arch/arm64/kernel/probes/kprobes.c |
| 3 | * |
| 4 | * Kprobes support for ARM64 |
| 5 | * |
| 6 | * Copyright (C) 2013 Linaro Limited. |
| 7 | * Author: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License version 2 as |
| 11 | * published by the Free Software Foundation. |
| 12 | * |
| 13 | * This program is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * General Public License for more details. |
| 17 | * |
| 18 | */ |
| 19 | #include <linux/kasan.h> |
| 20 | #include <linux/kernel.h> |
| 21 | #include <linux/kprobes.h> |
| 22 | #include <linux/module.h> |
| 23 | #include <linux/slab.h> |
| 24 | #include <linux/stop_machine.h> |
| 25 | #include <linux/stringify.h> |
| 26 | #include <asm/traps.h> |
| 27 | #include <asm/ptrace.h> |
| 28 | #include <asm/cacheflush.h> |
| 29 | #include <asm/debug-monitors.h> |
| 30 | #include <asm/system_misc.h> |
| 31 | #include <asm/insn.h> |
| 32 | #include <asm/uaccess.h> |
| 33 | #include <asm/irq.h> |
| 34 | #include <asm-generic/sections.h> |
| 35 | |
| 36 | #include "decode-insn.h" |
| 37 | |
| 38 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
| 39 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
| 40 | |
| 41 | static void __kprobes |
| 42 | post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); |
| 43 | |
| 44 | static void __kprobes arch_prepare_ss_slot(struct kprobe *p) |
| 45 | { |
| 46 | /* prepare insn slot */ |
| 47 | p->ainsn.insn[0] = cpu_to_le32(p->opcode); |
| 48 | |
| 49 | flush_icache_range((uintptr_t) (p->ainsn.insn), |
| 50 | (uintptr_t) (p->ainsn.insn) + |
| 51 | MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
| 52 | |
| 53 | /* |
| 54 | * Needs restoring of return address after stepping xol. |
| 55 | */ |
| 56 | p->ainsn.restore = (unsigned long) p->addr + |
| 57 | sizeof(kprobe_opcode_t); |
| 58 | } |
| 59 | |
| 60 | static void __kprobes arch_prepare_simulate(struct kprobe *p) |
| 61 | { |
| 62 | /* This instructions is not executed xol. No need to adjust the PC */ |
| 63 | p->ainsn.restore = 0; |
| 64 | } |
| 65 | |
| 66 | static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs) |
| 67 | { |
| 68 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 69 | |
| 70 | if (p->ainsn.handler) |
| 71 | p->ainsn.handler((u32)p->opcode, (long)p->addr, regs); |
| 72 | |
| 73 | /* single step simulated, now go for post processing */ |
| 74 | post_kprobe_handler(kcb, regs); |
| 75 | } |
| 76 | |
| 77 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
| 78 | { |
| 79 | unsigned long probe_addr = (unsigned long)p->addr; |
| 80 | extern char __start_rodata[]; |
| 81 | extern char __end_rodata[]; |
| 82 | |
| 83 | if (probe_addr & 0x3) |
| 84 | return -EINVAL; |
| 85 | |
| 86 | /* copy instruction */ |
| 87 | p->opcode = le32_to_cpu(*p->addr); |
| 88 | |
| 89 | if (in_exception_text(probe_addr)) |
| 90 | return -EINVAL; |
| 91 | if (probe_addr >= (unsigned long) __start_rodata && |
| 92 | probe_addr <= (unsigned long) __end_rodata) |
| 93 | return -EINVAL; |
| 94 | |
| 95 | /* decode instruction */ |
| 96 | switch (arm_kprobe_decode_insn(p->addr, &p->ainsn)) { |
| 97 | case INSN_REJECTED: /* insn not supported */ |
| 98 | return -EINVAL; |
| 99 | |
| 100 | case INSN_GOOD_NO_SLOT: /* insn need simulation */ |
| 101 | p->ainsn.insn = NULL; |
| 102 | break; |
| 103 | |
| 104 | case INSN_GOOD: /* instruction uses slot */ |
| 105 | p->ainsn.insn = get_insn_slot(); |
| 106 | if (!p->ainsn.insn) |
| 107 | return -ENOMEM; |
| 108 | break; |
| 109 | }; |
| 110 | |
| 111 | /* prepare the instruction */ |
| 112 | if (p->ainsn.insn) |
| 113 | arch_prepare_ss_slot(p); |
| 114 | else |
| 115 | arch_prepare_simulate(p); |
| 116 | |
| 117 | return 0; |
| 118 | } |
| 119 | |
| 120 | static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) |
| 121 | { |
| 122 | void *addrs[1]; |
| 123 | u32 insns[1]; |
| 124 | |
| 125 | addrs[0] = (void *)addr; |
| 126 | insns[0] = (u32)opcode; |
| 127 | |
| 128 | return aarch64_insn_patch_text(addrs, insns, 1); |
| 129 | } |
| 130 | |
| 131 | /* arm kprobe: install breakpoint in text */ |
| 132 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
| 133 | { |
| 134 | patch_text(p->addr, BRK64_OPCODE_KPROBES); |
| 135 | } |
| 136 | |
| 137 | /* disarm kprobe: remove breakpoint from text */ |
| 138 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
| 139 | { |
| 140 | patch_text(p->addr, p->opcode); |
| 141 | } |
| 142 | |
| 143 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
| 144 | { |
| 145 | if (p->ainsn.insn) { |
| 146 | free_insn_slot(p->ainsn.insn, 0); |
| 147 | p->ainsn.insn = NULL; |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
| 152 | { |
| 153 | kcb->prev_kprobe.kp = kprobe_running(); |
| 154 | kcb->prev_kprobe.status = kcb->kprobe_status; |
| 155 | } |
| 156 | |
| 157 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
| 158 | { |
| 159 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
| 160 | kcb->kprobe_status = kcb->prev_kprobe.status; |
| 161 | } |
| 162 | |
| 163 | static void __kprobes set_current_kprobe(struct kprobe *p) |
| 164 | { |
| 165 | __this_cpu_write(current_kprobe, p); |
| 166 | } |
| 167 | |
| 168 | /* |
| 169 | * When PSTATE.D is set (masked), then software step exceptions can not be |
| 170 | * generated. |
| 171 | * SPSR's D bit shows the value of PSTATE.D immediately before the |
| 172 | * exception was taken. PSTATE.D is set while entering into any exception |
| 173 | * mode, however software clears it for any normal (none-debug-exception) |
| 174 | * mode in the exception entry. Therefore, when we are entering into kprobe |
| 175 | * breakpoint handler from any normal mode then SPSR.D bit is already |
| 176 | * cleared, however it is set when we are entering from any debug exception |
| 177 | * mode. |
| 178 | * Since we always need to generate single step exception after a kprobe |
| 179 | * breakpoint exception therefore we need to clear it unconditionally, when |
| 180 | * we become sure that the current breakpoint exception is for kprobe. |
| 181 | */ |
| 182 | static void __kprobes |
| 183 | spsr_set_debug_flag(struct pt_regs *regs, int mask) |
| 184 | { |
| 185 | unsigned long spsr = regs->pstate; |
| 186 | |
| 187 | if (mask) |
| 188 | spsr |= PSR_D_BIT; |
| 189 | else |
| 190 | spsr &= ~PSR_D_BIT; |
| 191 | |
| 192 | regs->pstate = spsr; |
| 193 | } |
| 194 | |
| 195 | /* |
| 196 | * Interrupts need to be disabled before single-step mode is set, and not |
| 197 | * reenabled until after single-step mode ends. |
| 198 | * Without disabling interrupt on local CPU, there is a chance of |
| 199 | * interrupt occurrence in the period of exception return and start of |
| 200 | * out-of-line single-step, that result in wrongly single stepping |
| 201 | * into the interrupt handler. |
| 202 | */ |
| 203 | static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb, |
| 204 | struct pt_regs *regs) |
| 205 | { |
| 206 | kcb->saved_irqflag = regs->pstate; |
| 207 | regs->pstate |= PSR_I_BIT; |
| 208 | } |
| 209 | |
| 210 | static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb, |
| 211 | struct pt_regs *regs) |
| 212 | { |
| 213 | if (kcb->saved_irqflag & PSR_I_BIT) |
| 214 | regs->pstate |= PSR_I_BIT; |
| 215 | else |
| 216 | regs->pstate &= ~PSR_I_BIT; |
| 217 | } |
| 218 | |
| 219 | static void __kprobes |
| 220 | set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr) |
| 221 | { |
| 222 | kcb->ss_ctx.ss_pending = true; |
| 223 | kcb->ss_ctx.match_addr = addr + sizeof(kprobe_opcode_t); |
| 224 | } |
| 225 | |
| 226 | static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb) |
| 227 | { |
| 228 | kcb->ss_ctx.ss_pending = false; |
| 229 | kcb->ss_ctx.match_addr = 0; |
| 230 | } |
| 231 | |
| 232 | static void __kprobes setup_singlestep(struct kprobe *p, |
| 233 | struct pt_regs *regs, |
| 234 | struct kprobe_ctlblk *kcb, int reenter) |
| 235 | { |
| 236 | unsigned long slot; |
| 237 | |
| 238 | if (reenter) { |
| 239 | save_previous_kprobe(kcb); |
| 240 | set_current_kprobe(p); |
| 241 | kcb->kprobe_status = KPROBE_REENTER; |
| 242 | } else { |
| 243 | kcb->kprobe_status = KPROBE_HIT_SS; |
| 244 | } |
| 245 | |
| 246 | |
| 247 | if (p->ainsn.insn) { |
| 248 | /* prepare for single stepping */ |
| 249 | slot = (unsigned long)p->ainsn.insn; |
| 250 | |
| 251 | set_ss_context(kcb, slot); /* mark pending ss */ |
| 252 | |
| 253 | spsr_set_debug_flag(regs, 0); |
| 254 | |
| 255 | /* IRQs and single stepping do not mix well. */ |
| 256 | kprobes_save_local_irqflag(kcb, regs); |
| 257 | kernel_enable_single_step(regs); |
| 258 | instruction_pointer_set(regs, slot); |
| 259 | } else { |
| 260 | /* insn simulation */ |
| 261 | arch_simulate_insn(p, regs); |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | static int __kprobes reenter_kprobe(struct kprobe *p, |
| 266 | struct pt_regs *regs, |
| 267 | struct kprobe_ctlblk *kcb) |
| 268 | { |
| 269 | switch (kcb->kprobe_status) { |
| 270 | case KPROBE_HIT_SSDONE: |
| 271 | case KPROBE_HIT_ACTIVE: |
| 272 | kprobes_inc_nmissed_count(p); |
| 273 | setup_singlestep(p, regs, kcb, 1); |
| 274 | break; |
| 275 | case KPROBE_HIT_SS: |
| 276 | case KPROBE_REENTER: |
| 277 | pr_warn("Unrecoverable kprobe detected at %p.\n", p->addr); |
| 278 | dump_kprobe(p); |
| 279 | BUG(); |
| 280 | break; |
| 281 | default: |
| 282 | WARN_ON(1); |
| 283 | return 0; |
| 284 | } |
| 285 | |
| 286 | return 1; |
| 287 | } |
| 288 | |
| 289 | static void __kprobes |
| 290 | post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs) |
| 291 | { |
| 292 | struct kprobe *cur = kprobe_running(); |
| 293 | |
| 294 | if (!cur) |
| 295 | return; |
| 296 | |
| 297 | /* return addr restore if non-branching insn */ |
| 298 | if (cur->ainsn.restore != 0) |
| 299 | instruction_pointer_set(regs, cur->ainsn.restore); |
| 300 | |
| 301 | /* restore back original saved kprobe variables and continue */ |
| 302 | if (kcb->kprobe_status == KPROBE_REENTER) { |
| 303 | restore_previous_kprobe(kcb); |
| 304 | return; |
| 305 | } |
| 306 | /* call post handler */ |
| 307 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 308 | if (cur->post_handler) { |
| 309 | /* post_handler can hit breakpoint and single step |
| 310 | * again, so we enable D-flag for recursive exception. |
| 311 | */ |
| 312 | cur->post_handler(cur, regs, 0); |
| 313 | } |
| 314 | |
| 315 | reset_current_kprobe(); |
| 316 | } |
| 317 | |
| 318 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) |
| 319 | { |
| 320 | struct kprobe *cur = kprobe_running(); |
| 321 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 322 | |
| 323 | switch (kcb->kprobe_status) { |
| 324 | case KPROBE_HIT_SS: |
| 325 | case KPROBE_REENTER: |
| 326 | /* |
| 327 | * We are here because the instruction being single |
| 328 | * stepped caused a page fault. We reset the current |
| 329 | * kprobe and the ip points back to the probe address |
| 330 | * and allow the page fault handler to continue as a |
| 331 | * normal page fault. |
| 332 | */ |
| 333 | instruction_pointer_set(regs, (unsigned long) cur->addr); |
| 334 | if (!instruction_pointer(regs)) |
| 335 | BUG(); |
| 336 | |
| 337 | kernel_disable_single_step(); |
| 338 | |
| 339 | if (kcb->kprobe_status == KPROBE_REENTER) |
| 340 | restore_previous_kprobe(kcb); |
| 341 | else |
| 342 | reset_current_kprobe(); |
| 343 | |
| 344 | break; |
| 345 | case KPROBE_HIT_ACTIVE: |
| 346 | case KPROBE_HIT_SSDONE: |
| 347 | /* |
| 348 | * We increment the nmissed count for accounting, |
| 349 | * we can also use npre/npostfault count for accounting |
| 350 | * these specific fault cases. |
| 351 | */ |
| 352 | kprobes_inc_nmissed_count(cur); |
| 353 | |
| 354 | /* |
| 355 | * We come here because instructions in the pre/post |
| 356 | * handler caused the page_fault, this could happen |
| 357 | * if handler tries to access user space by |
| 358 | * copy_from_user(), get_user() etc. Let the |
| 359 | * user-specified handler try to fix it first. |
| 360 | */ |
| 361 | if (cur->fault_handler && cur->fault_handler(cur, regs, fsr)) |
| 362 | return 1; |
| 363 | |
| 364 | /* |
| 365 | * In case the user-specified fault handler returned |
| 366 | * zero, try to fix up. |
| 367 | */ |
| 368 | if (fixup_exception(regs)) |
| 369 | return 1; |
| 370 | } |
| 371 | return 0; |
| 372 | } |
| 373 | |
| 374 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
| 375 | unsigned long val, void *data) |
| 376 | { |
| 377 | return NOTIFY_DONE; |
| 378 | } |
| 379 | |
| 380 | static void __kprobes kprobe_handler(struct pt_regs *regs) |
| 381 | { |
| 382 | struct kprobe *p, *cur_kprobe; |
| 383 | struct kprobe_ctlblk *kcb; |
| 384 | unsigned long addr = instruction_pointer(regs); |
| 385 | |
| 386 | kcb = get_kprobe_ctlblk(); |
| 387 | cur_kprobe = kprobe_running(); |
| 388 | |
| 389 | p = get_kprobe((kprobe_opcode_t *) addr); |
| 390 | |
| 391 | if (p) { |
| 392 | if (cur_kprobe) { |
| 393 | if (reenter_kprobe(p, regs, kcb)) |
| 394 | return; |
| 395 | } else { |
| 396 | /* Probe hit */ |
| 397 | set_current_kprobe(p); |
| 398 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| 399 | |
| 400 | /* |
| 401 | * If we have no pre-handler or it returned 0, we |
| 402 | * continue with normal processing. If we have a |
| 403 | * pre-handler and it returned non-zero, it prepped |
| 404 | * for calling the break_handler below on re-entry, |
| 405 | * so get out doing nothing more here. |
| 406 | * |
| 407 | * pre_handler can hit a breakpoint and can step thru |
| 408 | * before return, keep PSTATE D-flag enabled until |
| 409 | * pre_handler return back. |
| 410 | */ |
| 411 | if (!p->pre_handler || !p->pre_handler(p, regs)) { |
| 412 | setup_singlestep(p, regs, kcb, 0); |
| 413 | return; |
| 414 | } |
| 415 | } |
| 416 | } else if ((le32_to_cpu(*(kprobe_opcode_t *) addr) == |
| 417 | BRK64_OPCODE_KPROBES) && cur_kprobe) { |
| 418 | /* We probably hit a jprobe. Call its break handler. */ |
| 419 | if (cur_kprobe->break_handler && |
| 420 | cur_kprobe->break_handler(cur_kprobe, regs)) { |
| 421 | setup_singlestep(cur_kprobe, regs, kcb, 0); |
| 422 | return; |
| 423 | } |
| 424 | } |
| 425 | /* |
| 426 | * The breakpoint instruction was removed right |
| 427 | * after we hit it. Another cpu has removed |
| 428 | * either a probepoint or a debugger breakpoint |
| 429 | * at this address. In either case, no further |
| 430 | * handling of this interrupt is appropriate. |
| 431 | * Return back to original instruction, and continue. |
| 432 | */ |
| 433 | } |
| 434 | |
| 435 | static int __kprobes |
| 436 | kprobe_ss_hit(struct kprobe_ctlblk *kcb, unsigned long addr) |
| 437 | { |
| 438 | if ((kcb->ss_ctx.ss_pending) |
| 439 | && (kcb->ss_ctx.match_addr == addr)) { |
| 440 | clear_ss_context(kcb); /* clear pending ss */ |
| 441 | return DBG_HOOK_HANDLED; |
| 442 | } |
| 443 | /* not ours, kprobes should ignore it */ |
| 444 | return DBG_HOOK_ERROR; |
| 445 | } |
| 446 | |
| 447 | int __kprobes |
| 448 | kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr) |
| 449 | { |
| 450 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 451 | int retval; |
| 452 | |
| 453 | /* return error if this is not our step */ |
| 454 | retval = kprobe_ss_hit(kcb, instruction_pointer(regs)); |
| 455 | |
| 456 | if (retval == DBG_HOOK_HANDLED) { |
| 457 | kprobes_restore_local_irqflag(kcb, regs); |
| 458 | kernel_disable_single_step(); |
| 459 | |
| 460 | post_kprobe_handler(kcb, regs); |
| 461 | } |
| 462 | |
| 463 | return retval; |
| 464 | } |
| 465 | |
| 466 | int __kprobes |
| 467 | kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr) |
| 468 | { |
| 469 | kprobe_handler(regs); |
| 470 | return DBG_HOOK_HANDLED; |
| 471 | } |
| 472 | |
| 473 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
| 474 | { |
| 475 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 476 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 477 | |
| 478 | kcb->jprobe_saved_regs = *regs; |
| 479 | /* |
| 480 | * Since we can't be sure where in the stack frame "stacked" |
| 481 | * pass-by-value arguments are stored we just don't try to |
| 482 | * duplicate any of the stack. Do not use jprobes on functions that |
| 483 | * use more than 64 bytes (after padding each to an 8 byte boundary) |
| 484 | * of arguments, or pass individual arguments larger than 16 bytes. |
| 485 | */ |
| 486 | |
| 487 | instruction_pointer_set(regs, (unsigned long) jp->entry); |
| 488 | preempt_disable(); |
| 489 | pause_graph_tracing(); |
| 490 | return 1; |
| 491 | } |
| 492 | |
| 493 | void __kprobes jprobe_return(void) |
| 494 | { |
| 495 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 496 | |
| 497 | /* |
| 498 | * Jprobe handler return by entering break exception, |
| 499 | * encoded same as kprobe, but with following conditions |
| 500 | * -a special PC to identify it from the other kprobes. |
| 501 | * -restore stack addr to original saved pt_regs |
| 502 | */ |
| 503 | asm volatile(" mov sp, %0 \n" |
| 504 | "jprobe_return_break: brk %1 \n" |
| 505 | : |
| 506 | : "r" (kcb->jprobe_saved_regs.sp), |
| 507 | "I" (BRK64_ESR_KPROBES) |
| 508 | : "memory"); |
| 509 | |
| 510 | unreachable(); |
| 511 | } |
| 512 | |
| 513 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
| 514 | { |
| 515 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 516 | long stack_addr = kcb->jprobe_saved_regs.sp; |
| 517 | long orig_sp = kernel_stack_pointer(regs); |
| 518 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 519 | extern const char jprobe_return_break[]; |
| 520 | |
| 521 | if (instruction_pointer(regs) != (u64) jprobe_return_break) |
| 522 | return 0; |
| 523 | |
| 524 | if (orig_sp != stack_addr) { |
| 525 | struct pt_regs *saved_regs = |
| 526 | (struct pt_regs *)kcb->jprobe_saved_regs.sp; |
| 527 | pr_err("current sp %lx does not match saved sp %lx\n", |
| 528 | orig_sp, stack_addr); |
| 529 | pr_err("Saved registers for jprobe %p\n", jp); |
| 530 | show_regs(saved_regs); |
| 531 | pr_err("Current registers\n"); |
| 532 | show_regs(regs); |
| 533 | BUG(); |
| 534 | } |
| 535 | unpause_graph_tracing(); |
| 536 | *regs = kcb->jprobe_saved_regs; |
| 537 | preempt_enable_no_resched(); |
| 538 | return 1; |
| 539 | } |
| 540 | |
| 541 | bool arch_within_kprobe_blacklist(unsigned long addr) |
| 542 | { |
| 543 | extern char __idmap_text_start[], __idmap_text_end[]; |
| 544 | extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[]; |
| 545 | |
| 546 | if ((addr >= (unsigned long)__kprobes_text_start && |
| 547 | addr < (unsigned long)__kprobes_text_end) || |
| 548 | (addr >= (unsigned long)__entry_text_start && |
| 549 | addr < (unsigned long)__entry_text_end) || |
| 550 | (addr >= (unsigned long)__idmap_text_start && |
| 551 | addr < (unsigned long)__idmap_text_end) || |
| 552 | !!search_exception_tables(addr)) |
| 553 | return true; |
| 554 | |
| 555 | if (!is_kernel_in_hyp_mode()) { |
| 556 | if ((addr >= (unsigned long)__hyp_text_start && |
| 557 | addr < (unsigned long)__hyp_text_end) || |
| 558 | (addr >= (unsigned long)__hyp_idmap_text_start && |
| 559 | addr < (unsigned long)__hyp_idmap_text_end)) |
| 560 | return true; |
| 561 | } |
| 562 | |
| 563 | return false; |
| 564 | } |
| 565 | |
| 566 | void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) |
| 567 | { |
| 568 | struct kretprobe_instance *ri = NULL; |
| 569 | struct hlist_head *head, empty_rp; |
| 570 | struct hlist_node *tmp; |
| 571 | unsigned long flags, orig_ret_address = 0; |
| 572 | unsigned long trampoline_address = |
| 573 | (unsigned long)&kretprobe_trampoline; |
| 574 | kprobe_opcode_t *correct_ret_addr = NULL; |
| 575 | |
| 576 | INIT_HLIST_HEAD(&empty_rp); |
| 577 | kretprobe_hash_lock(current, &head, &flags); |
| 578 | |
| 579 | /* |
| 580 | * It is possible to have multiple instances associated with a given |
| 581 | * task either because multiple functions in the call path have |
| 582 | * return probes installed on them, and/or more than one |
| 583 | * return probe was registered for a target function. |
| 584 | * |
| 585 | * We can handle this because: |
| 586 | * - instances are always pushed into the head of the list |
| 587 | * - when multiple return probes are registered for the same |
| 588 | * function, the (chronologically) first instance's ret_addr |
| 589 | * will be the real return address, and all the rest will |
| 590 | * point to kretprobe_trampoline. |
| 591 | */ |
| 592 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
| 593 | if (ri->task != current) |
| 594 | /* another task is sharing our hash bucket */ |
| 595 | continue; |
| 596 | |
| 597 | orig_ret_address = (unsigned long)ri->ret_addr; |
| 598 | |
| 599 | if (orig_ret_address != trampoline_address) |
| 600 | /* |
| 601 | * This is the real return address. Any other |
| 602 | * instances associated with this task are for |
| 603 | * other calls deeper on the call stack |
| 604 | */ |
| 605 | break; |
| 606 | } |
| 607 | |
| 608 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
| 609 | |
| 610 | correct_ret_addr = ri->ret_addr; |
| 611 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
| 612 | if (ri->task != current) |
| 613 | /* another task is sharing our hash bucket */ |
| 614 | continue; |
| 615 | |
| 616 | orig_ret_address = (unsigned long)ri->ret_addr; |
| 617 | if (ri->rp && ri->rp->handler) { |
| 618 | __this_cpu_write(current_kprobe, &ri->rp->kp); |
| 619 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
| 620 | ri->ret_addr = correct_ret_addr; |
| 621 | ri->rp->handler(ri, regs); |
| 622 | __this_cpu_write(current_kprobe, NULL); |
| 623 | } |
| 624 | |
| 625 | recycle_rp_inst(ri, &empty_rp); |
| 626 | |
| 627 | if (orig_ret_address != trampoline_address) |
| 628 | /* |
| 629 | * This is the real return address. Any other |
| 630 | * instances associated with this task are for |
| 631 | * other calls deeper on the call stack |
| 632 | */ |
| 633 | break; |
| 634 | } |
| 635 | |
| 636 | kretprobe_hash_unlock(current, &flags); |
| 637 | |
| 638 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
| 639 | hlist_del(&ri->hlist); |
| 640 | kfree(ri); |
| 641 | } |
| 642 | return (void *)orig_ret_address; |
| 643 | } |
| 644 | |
| 645 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
| 646 | struct pt_regs *regs) |
| 647 | { |
| 648 | ri->ret_addr = (kprobe_opcode_t *)regs->regs[30]; |
| 649 | |
| 650 | /* replace return addr (x30) with trampoline */ |
| 651 | regs->regs[30] = (long)&kretprobe_trampoline; |
| 652 | } |
| 653 | |
| 654 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
| 655 | { |
| 656 | return 0; |
| 657 | } |
| 658 | |
| 659 | int __init arch_init_kprobes(void) |
| 660 | { |
| 661 | return 0; |
| 662 | } |