David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Kernel Probes (KProbes) |
| 3 | * arch/mips/kernel/kprobes.c |
| 4 | * |
| 5 | * Copyright 2006 Sony Corp. |
| 6 | * Copyright 2010 Cavium Networks |
| 7 | * |
| 8 | * Some portions copied from the powerpc version. |
| 9 | * |
| 10 | * Copyright (C) IBM Corporation, 2002, 2004 |
| 11 | * |
| 12 | * This program is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU General Public License as published by |
| 14 | * the Free Software Foundation; version 2 of the License. |
| 15 | * |
| 16 | * This program is distributed in the hope that it will be useful, |
| 17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 19 | * GNU General Public License for more details. |
| 20 | * |
| 21 | * You should have received a copy of the GNU General Public License |
| 22 | * along with this program; if not, write to the Free Software |
| 23 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 24 | */ |
| 25 | |
| 26 | #include <linux/kprobes.h> |
| 27 | #include <linux/preempt.h> |
Maneesh Soni | 41dde78 | 2011-11-08 17:04:54 +0530 | [diff] [blame] | 28 | #include <linux/uaccess.h> |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 29 | #include <linux/kdebug.h> |
| 30 | #include <linux/slab.h> |
| 31 | |
| 32 | #include <asm/ptrace.h> |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 33 | #include <asm/branch.h> |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 34 | #include <asm/break.h> |
Marcin Nowakowski | e3031b3 | 2016-09-30 11:33:45 +0200 | [diff] [blame] | 35 | |
| 36 | #include "probes-common.h" |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 37 | |
| 38 | static const union mips_instruction breakpoint_insn = { |
| 39 | .b_format = { |
| 40 | .opcode = spec_op, |
| 41 | .code = BRK_KPROBE_BP, |
| 42 | .func = break_op |
| 43 | } |
| 44 | }; |
| 45 | |
| 46 | static const union mips_instruction breakpoint2_insn = { |
| 47 | .b_format = { |
| 48 | .opcode = spec_op, |
| 49 | .code = BRK_KPROBE_SSTEPBP, |
| 50 | .func = break_op |
| 51 | } |
| 52 | }; |
| 53 | |
| 54 | DEFINE_PER_CPU(struct kprobe *, current_kprobe); |
| 55 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
| 56 | |
| 57 | static int __kprobes insn_has_delayslot(union mips_instruction insn) |
| 58 | { |
Marcin Nowakowski | e3031b3 | 2016-09-30 11:33:45 +0200 | [diff] [blame] | 59 | return __insn_has_delay_slot(insn); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 60 | } |
| 61 | |
Maneesh Soni | 9233c1e | 2011-11-08 17:05:35 +0530 | [diff] [blame] | 62 | /* |
| 63 | * insn_has_ll_or_sc function checks whether instruction is ll or sc |
| 64 | * one; putting breakpoint on top of atomic ll/sc pair is bad idea; |
| 65 | * so we need to prevent it and refuse kprobes insertion for such |
| 66 | * instructions; cannot do much about breakpoint in the middle of |
| 67 | * ll/sc pair; it is upto user to avoid those places |
| 68 | */ |
| 69 | static int __kprobes insn_has_ll_or_sc(union mips_instruction insn) |
| 70 | { |
| 71 | int ret = 0; |
| 72 | |
| 73 | switch (insn.i_format.opcode) { |
| 74 | case ll_op: |
| 75 | case lld_op: |
| 76 | case sc_op: |
| 77 | case scd_op: |
| 78 | ret = 1; |
| 79 | break; |
| 80 | default: |
| 81 | break; |
| 82 | } |
| 83 | return ret; |
| 84 | } |
| 85 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 86 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
| 87 | { |
| 88 | union mips_instruction insn; |
| 89 | union mips_instruction prev_insn; |
| 90 | int ret = 0; |
| 91 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 92 | insn = p->addr[0]; |
| 93 | |
Maneesh Soni | 9233c1e | 2011-11-08 17:05:35 +0530 | [diff] [blame] | 94 | if (insn_has_ll_or_sc(insn)) { |
| 95 | pr_notice("Kprobes for ll and sc instructions are not" |
| 96 | "supported\n"); |
| 97 | ret = -EINVAL; |
| 98 | goto out; |
| 99 | } |
| 100 | |
Maneesh Soni | 41dde78 | 2011-11-08 17:04:54 +0530 | [diff] [blame] | 101 | if ((probe_kernel_read(&prev_insn, p->addr - 1, |
| 102 | sizeof(mips_instruction)) == 0) && |
| 103 | insn_has_delayslot(prev_insn)) { |
| 104 | pr_notice("Kprobes for branch delayslot are not supported\n"); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 105 | ret = -EINVAL; |
| 106 | goto out; |
| 107 | } |
| 108 | |
Marcin Nowakowski | d05c513 | 2016-09-30 11:33:46 +0200 | [diff] [blame] | 109 | if (__insn_is_compact_branch(insn)) { |
| 110 | pr_notice("Kprobes for compact branches are not supported\n"); |
| 111 | ret = -EINVAL; |
| 112 | goto out; |
| 113 | } |
| 114 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 115 | /* insn: must be on special executable page on mips. */ |
| 116 | p->ainsn.insn = get_insn_slot(); |
| 117 | if (!p->ainsn.insn) { |
| 118 | ret = -ENOMEM; |
| 119 | goto out; |
| 120 | } |
| 121 | |
| 122 | /* |
| 123 | * In the kprobe->ainsn.insn[] array we store the original |
| 124 | * instruction at index zero and a break trap instruction at |
| 125 | * index one. |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 126 | * |
| 127 | * On MIPS arch if the instruction at probed address is a |
| 128 | * branch instruction, we need to execute the instruction at |
| 129 | * Branch Delayslot (BD) at the time of probe hit. As MIPS also |
| 130 | * doesn't have single stepping support, the BD instruction can |
| 131 | * not be executed in-line and it would be executed on SSOL slot |
| 132 | * using a normal breakpoint instruction in the next slot. |
| 133 | * So, read the instruction and save it for later execution. |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 134 | */ |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 135 | if (insn_has_delayslot(insn)) |
| 136 | memcpy(&p->ainsn.insn[0], p->addr + 1, sizeof(kprobe_opcode_t)); |
| 137 | else |
| 138 | memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t)); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 139 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 140 | p->ainsn.insn[1] = breakpoint2_insn; |
| 141 | p->opcode = *p->addr; |
| 142 | |
| 143 | out: |
| 144 | return ret; |
| 145 | } |
| 146 | |
| 147 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
| 148 | { |
| 149 | *p->addr = breakpoint_insn; |
| 150 | flush_insn_slot(p); |
| 151 | } |
| 152 | |
| 153 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
| 154 | { |
| 155 | *p->addr = p->opcode; |
| 156 | flush_insn_slot(p); |
| 157 | } |
| 158 | |
| 159 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
| 160 | { |
Masami Hiramatsu | 22047b8 | 2013-05-22 08:34:13 +0000 | [diff] [blame] | 161 | if (p->ainsn.insn) { |
| 162 | free_insn_slot(p->ainsn.insn, 0); |
| 163 | p->ainsn.insn = NULL; |
| 164 | } |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 165 | } |
| 166 | |
| 167 | static void save_previous_kprobe(struct kprobe_ctlblk *kcb) |
| 168 | { |
| 169 | kcb->prev_kprobe.kp = kprobe_running(); |
| 170 | kcb->prev_kprobe.status = kcb->kprobe_status; |
| 171 | kcb->prev_kprobe.old_SR = kcb->kprobe_old_SR; |
| 172 | kcb->prev_kprobe.saved_SR = kcb->kprobe_saved_SR; |
| 173 | kcb->prev_kprobe.saved_epc = kcb->kprobe_saved_epc; |
| 174 | } |
| 175 | |
| 176 | static void restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
| 177 | { |
Christoph Lameter | 3589871 | 2014-08-17 12:30:44 -0500 | [diff] [blame] | 178 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 179 | kcb->kprobe_status = kcb->prev_kprobe.status; |
| 180 | kcb->kprobe_old_SR = kcb->prev_kprobe.old_SR; |
| 181 | kcb->kprobe_saved_SR = kcb->prev_kprobe.saved_SR; |
| 182 | kcb->kprobe_saved_epc = kcb->prev_kprobe.saved_epc; |
| 183 | } |
| 184 | |
| 185 | static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
| 186 | struct kprobe_ctlblk *kcb) |
| 187 | { |
Christoph Lameter | 3589871 | 2014-08-17 12:30:44 -0500 | [diff] [blame] | 188 | __this_cpu_write(current_kprobe, p); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 189 | kcb->kprobe_saved_SR = kcb->kprobe_old_SR = (regs->cp0_status & ST0_IE); |
| 190 | kcb->kprobe_saved_epc = regs->cp0_epc; |
| 191 | } |
| 192 | |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 193 | /** |
| 194 | * evaluate_branch_instrucion - |
| 195 | * |
| 196 | * Evaluate the branch instruction at probed address during probe hit. The |
| 197 | * result of evaluation would be the updated epc. The insturction in delayslot |
| 198 | * would actually be single stepped using a normal breakpoint) on SSOL slot. |
| 199 | * |
| 200 | * The result is also saved in the kprobe control block for later use, |
| 201 | * in case we need to execute the delayslot instruction. The latter will be |
| 202 | * false for NOP instruction in dealyslot and the branch-likely instructions |
| 203 | * when the branch is taken. And for those cases we set a flag as |
| 204 | * SKIP_DELAYSLOT in the kprobe control block |
| 205 | */ |
| 206 | static int evaluate_branch_instruction(struct kprobe *p, struct pt_regs *regs, |
| 207 | struct kprobe_ctlblk *kcb) |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 208 | { |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 209 | union mips_instruction insn = p->opcode; |
| 210 | long epc; |
| 211 | int ret = 0; |
| 212 | |
| 213 | epc = regs->cp0_epc; |
| 214 | if (epc & 3) |
| 215 | goto unaligned; |
| 216 | |
| 217 | if (p->ainsn.insn->word == 0) |
| 218 | kcb->flags |= SKIP_DELAYSLOT; |
| 219 | else |
| 220 | kcb->flags &= ~SKIP_DELAYSLOT; |
| 221 | |
| 222 | ret = __compute_return_epc_for_insn(regs, insn); |
| 223 | if (ret < 0) |
| 224 | return ret; |
| 225 | |
| 226 | if (ret == BRANCH_LIKELY_TAKEN) |
| 227 | kcb->flags |= SKIP_DELAYSLOT; |
| 228 | |
| 229 | kcb->target_epc = regs->cp0_epc; |
| 230 | |
| 231 | return 0; |
| 232 | |
| 233 | unaligned: |
| 234 | pr_notice("%s: unaligned epc - sending SIGBUS.\n", current->comm); |
| 235 | force_sig(SIGBUS, current); |
| 236 | return -EFAULT; |
| 237 | |
| 238 | } |
| 239 | |
| 240 | static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs, |
| 241 | struct kprobe_ctlblk *kcb) |
| 242 | { |
| 243 | int ret = 0; |
| 244 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 245 | regs->cp0_status &= ~ST0_IE; |
| 246 | |
| 247 | /* single step inline if the instruction is a break */ |
| 248 | if (p->opcode.word == breakpoint_insn.word || |
| 249 | p->opcode.word == breakpoint2_insn.word) |
| 250 | regs->cp0_epc = (unsigned long)p->addr; |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 251 | else if (insn_has_delayslot(p->opcode)) { |
| 252 | ret = evaluate_branch_instruction(p, regs, kcb); |
| 253 | if (ret < 0) { |
| 254 | pr_notice("Kprobes: Error in evaluating branch\n"); |
| 255 | return; |
| 256 | } |
| 257 | } |
| 258 | regs->cp0_epc = (unsigned long)&p->ainsn.insn[0]; |
| 259 | } |
| 260 | |
| 261 | /* |
| 262 | * Called after single-stepping. p->addr is the address of the |
| 263 | * instruction whose first byte has been replaced by the "break 0" |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 264 | * instruction. To avoid the SMP problems that can occur when we |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 265 | * temporarily put back the original opcode to single-step, we |
| 266 | * single-stepped a copy of the instruction. The address of this |
| 267 | * copy is p->ainsn.insn. |
| 268 | * |
| 269 | * This function prepares to return from the post-single-step |
| 270 | * breakpoint trap. In case of branch instructions, the target |
| 271 | * epc to be restored. |
| 272 | */ |
| 273 | static void __kprobes resume_execution(struct kprobe *p, |
| 274 | struct pt_regs *regs, |
| 275 | struct kprobe_ctlblk *kcb) |
| 276 | { |
| 277 | if (insn_has_delayslot(p->opcode)) |
| 278 | regs->cp0_epc = kcb->target_epc; |
| 279 | else { |
| 280 | unsigned long orig_epc = kcb->kprobe_saved_epc; |
| 281 | regs->cp0_epc = orig_epc + 4; |
| 282 | } |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 283 | } |
| 284 | |
| 285 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
| 286 | { |
| 287 | struct kprobe *p; |
| 288 | int ret = 0; |
| 289 | kprobe_opcode_t *addr; |
| 290 | struct kprobe_ctlblk *kcb; |
| 291 | |
| 292 | addr = (kprobe_opcode_t *) regs->cp0_epc; |
| 293 | |
| 294 | /* |
| 295 | * We don't want to be preempted for the entire |
| 296 | * duration of kprobe processing |
| 297 | */ |
| 298 | preempt_disable(); |
| 299 | kcb = get_kprobe_ctlblk(); |
| 300 | |
| 301 | /* Check we're not actually recursing */ |
| 302 | if (kprobe_running()) { |
| 303 | p = get_kprobe(addr); |
| 304 | if (p) { |
| 305 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
| 306 | p->ainsn.insn->word == breakpoint_insn.word) { |
| 307 | regs->cp0_status &= ~ST0_IE; |
| 308 | regs->cp0_status |= kcb->kprobe_saved_SR; |
| 309 | goto no_kprobe; |
| 310 | } |
| 311 | /* |
| 312 | * We have reentered the kprobe_handler(), since |
| 313 | * another probe was hit while within the handler. |
| 314 | * We here save the original kprobes variables and |
| 315 | * just single step on the instruction of the new probe |
| 316 | * without calling any user handlers. |
| 317 | */ |
| 318 | save_previous_kprobe(kcb); |
| 319 | set_current_kprobe(p, regs, kcb); |
| 320 | kprobes_inc_nmissed_count(p); |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 321 | prepare_singlestep(p, regs, kcb); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 322 | kcb->kprobe_status = KPROBE_REENTER; |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 323 | if (kcb->flags & SKIP_DELAYSLOT) { |
| 324 | resume_execution(p, regs, kcb); |
| 325 | restore_previous_kprobe(kcb); |
| 326 | preempt_enable_no_resched(); |
| 327 | } |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 328 | return 1; |
| 329 | } else { |
| 330 | if (addr->word != breakpoint_insn.word) { |
| 331 | /* |
| 332 | * The breakpoint instruction was removed by |
| 333 | * another cpu right after we hit, no further |
| 334 | * handling of this interrupt is appropriate |
| 335 | */ |
| 336 | ret = 1; |
| 337 | goto no_kprobe; |
| 338 | } |
Christoph Lameter | 3589871 | 2014-08-17 12:30:44 -0500 | [diff] [blame] | 339 | p = __this_cpu_read(current_kprobe); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 340 | if (p->break_handler && p->break_handler(p, regs)) |
| 341 | goto ss_probe; |
| 342 | } |
| 343 | goto no_kprobe; |
| 344 | } |
| 345 | |
| 346 | p = get_kprobe(addr); |
| 347 | if (!p) { |
| 348 | if (addr->word != breakpoint_insn.word) { |
| 349 | /* |
| 350 | * The breakpoint instruction was removed right |
| 351 | * after we hit it. Another cpu has removed |
| 352 | * either a probepoint or a debugger breakpoint |
| 353 | * at this address. In either case, no further |
| 354 | * handling of this interrupt is appropriate. |
| 355 | */ |
| 356 | ret = 1; |
| 357 | } |
| 358 | /* Not one of ours: let kernel handle it */ |
| 359 | goto no_kprobe; |
| 360 | } |
| 361 | |
| 362 | set_current_kprobe(p, regs, kcb); |
| 363 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| 364 | |
| 365 | if (p->pre_handler && p->pre_handler(p, regs)) { |
| 366 | /* handler has already set things up, so skip ss setup */ |
| 367 | return 1; |
| 368 | } |
| 369 | |
| 370 | ss_probe: |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 371 | prepare_singlestep(p, regs, kcb); |
| 372 | if (kcb->flags & SKIP_DELAYSLOT) { |
| 373 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 374 | if (p->post_handler) |
| 375 | p->post_handler(p, regs, 0); |
| 376 | resume_execution(p, regs, kcb); |
| 377 | preempt_enable_no_resched(); |
| 378 | } else |
| 379 | kcb->kprobe_status = KPROBE_HIT_SS; |
| 380 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 381 | return 1; |
| 382 | |
| 383 | no_kprobe: |
| 384 | preempt_enable_no_resched(); |
| 385 | return ret; |
| 386 | |
| 387 | } |
| 388 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 389 | static inline int post_kprobe_handler(struct pt_regs *regs) |
| 390 | { |
| 391 | struct kprobe *cur = kprobe_running(); |
| 392 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 393 | |
| 394 | if (!cur) |
| 395 | return 0; |
| 396 | |
| 397 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
| 398 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 399 | cur->post_handler(cur, regs, 0); |
| 400 | } |
| 401 | |
| 402 | resume_execution(cur, regs, kcb); |
| 403 | |
| 404 | regs->cp0_status |= kcb->kprobe_saved_SR; |
| 405 | |
| 406 | /* Restore back the original saved kprobes variables and continue. */ |
| 407 | if (kcb->kprobe_status == KPROBE_REENTER) { |
| 408 | restore_previous_kprobe(kcb); |
| 409 | goto out; |
| 410 | } |
| 411 | reset_current_kprobe(); |
| 412 | out: |
| 413 | preempt_enable_no_resched(); |
| 414 | |
| 415 | return 1; |
| 416 | } |
| 417 | |
| 418 | static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
| 419 | { |
| 420 | struct kprobe *cur = kprobe_running(); |
| 421 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 422 | |
| 423 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) |
| 424 | return 1; |
| 425 | |
| 426 | if (kcb->kprobe_status & KPROBE_HIT_SS) { |
| 427 | resume_execution(cur, regs, kcb); |
| 428 | regs->cp0_status |= kcb->kprobe_old_SR; |
| 429 | |
| 430 | reset_current_kprobe(); |
| 431 | preempt_enable_no_resched(); |
| 432 | } |
| 433 | return 0; |
| 434 | } |
| 435 | |
| 436 | /* |
| 437 | * Wrapper routine for handling exceptions. |
| 438 | */ |
| 439 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
| 440 | unsigned long val, void *data) |
| 441 | { |
| 442 | |
| 443 | struct die_args *args = (struct die_args *)data; |
| 444 | int ret = NOTIFY_DONE; |
| 445 | |
| 446 | switch (val) { |
| 447 | case DIE_BREAK: |
| 448 | if (kprobe_handler(args->regs)) |
| 449 | ret = NOTIFY_STOP; |
| 450 | break; |
| 451 | case DIE_SSTEPBP: |
| 452 | if (post_kprobe_handler(args->regs)) |
| 453 | ret = NOTIFY_STOP; |
| 454 | break; |
| 455 | |
| 456 | case DIE_PAGE_FAULT: |
| 457 | /* kprobe_running() needs smp_processor_id() */ |
| 458 | preempt_disable(); |
| 459 | |
| 460 | if (kprobe_running() |
| 461 | && kprobe_fault_handler(args->regs, args->trapnr)) |
| 462 | ret = NOTIFY_STOP; |
| 463 | preempt_enable(); |
| 464 | break; |
| 465 | default: |
| 466 | break; |
| 467 | } |
| 468 | return ret; |
| 469 | } |
| 470 | |
| 471 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
| 472 | { |
| 473 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 474 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 475 | |
| 476 | kcb->jprobe_saved_regs = *regs; |
| 477 | kcb->jprobe_saved_sp = regs->regs[29]; |
| 478 | |
| 479 | memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp, |
| 480 | MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); |
| 481 | |
| 482 | regs->cp0_epc = (unsigned long)(jp->entry); |
| 483 | |
| 484 | return 1; |
| 485 | } |
| 486 | |
| 487 | /* Defined in the inline asm below. */ |
| 488 | void jprobe_return_end(void); |
| 489 | |
| 490 | void __kprobes jprobe_return(void) |
| 491 | { |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 492 | /* Assembler quirk necessitates this '0,code' business. */ |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 493 | asm volatile( |
| 494 | "break 0,%0\n\t" |
| 495 | ".globl jprobe_return_end\n" |
| 496 | "jprobe_return_end:\n" |
| 497 | : : "n" (BRK_KPROBE_BP) : "memory"); |
| 498 | } |
| 499 | |
| 500 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
| 501 | { |
| 502 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 503 | |
| 504 | if (regs->cp0_epc >= (unsigned long)jprobe_return && |
| 505 | regs->cp0_epc <= (unsigned long)jprobe_return_end) { |
| 506 | *regs = kcb->jprobe_saved_regs; |
| 507 | memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack, |
| 508 | MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); |
| 509 | preempt_enable_no_resched(); |
| 510 | |
| 511 | return 1; |
| 512 | } |
| 513 | return 0; |
| 514 | } |
| 515 | |
| 516 | /* |
| 517 | * Function return probe trampoline: |
| 518 | * - init_kprobes() establishes a probepoint here |
| 519 | * - When the probed function returns, this probe causes the |
| 520 | * handlers to fire |
| 521 | */ |
| 522 | static void __used kretprobe_trampoline_holder(void) |
| 523 | { |
| 524 | asm volatile( |
| 525 | ".set push\n\t" |
| 526 | /* Keep the assembler from reordering and placing JR here. */ |
| 527 | ".set noreorder\n\t" |
| 528 | "nop\n\t" |
| 529 | ".global kretprobe_trampoline\n" |
| 530 | "kretprobe_trampoline:\n\t" |
| 531 | "nop\n\t" |
| 532 | ".set pop" |
| 533 | : : : "memory"); |
| 534 | } |
| 535 | |
| 536 | void kretprobe_trampoline(void); |
| 537 | |
| 538 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
| 539 | struct pt_regs *regs) |
| 540 | { |
| 541 | ri->ret_addr = (kprobe_opcode_t *) regs->regs[31]; |
| 542 | |
| 543 | /* Replace the return addr with trampoline addr */ |
| 544 | regs->regs[31] = (unsigned long)kretprobe_trampoline; |
| 545 | } |
| 546 | |
| 547 | /* |
| 548 | * Called when the probe at kretprobe trampoline is hit |
| 549 | */ |
| 550 | static int __kprobes trampoline_probe_handler(struct kprobe *p, |
| 551 | struct pt_regs *regs) |
| 552 | { |
| 553 | struct kretprobe_instance *ri = NULL; |
| 554 | struct hlist_head *head, empty_rp; |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 555 | struct hlist_node *tmp; |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 556 | unsigned long flags, orig_ret_address = 0; |
| 557 | unsigned long trampoline_address = (unsigned long)kretprobe_trampoline; |
| 558 | |
| 559 | INIT_HLIST_HEAD(&empty_rp); |
| 560 | kretprobe_hash_lock(current, &head, &flags); |
| 561 | |
| 562 | /* |
| 563 | * It is possible to have multiple instances associated with a given |
| 564 | * task either because an multiple functions in the call path |
| 565 | * have a return probe installed on them, and/or more than one return |
| 566 | * return probe was registered for a target function. |
| 567 | * |
| 568 | * We can handle this because: |
| 569 | * - instances are always inserted at the head of the list |
| 570 | * - when multiple return probes are registered for the same |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 571 | * function, the first instance's ret_addr will point to the |
| 572 | * real return address, and all the rest will point to |
| 573 | * kretprobe_trampoline |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 574 | */ |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 575 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 576 | if (ri->task != current) |
| 577 | /* another task is sharing our hash bucket */ |
| 578 | continue; |
| 579 | |
| 580 | if (ri->rp && ri->rp->handler) |
| 581 | ri->rp->handler(ri, regs); |
| 582 | |
| 583 | orig_ret_address = (unsigned long)ri->ret_addr; |
| 584 | recycle_rp_inst(ri, &empty_rp); |
| 585 | |
| 586 | if (orig_ret_address != trampoline_address) |
| 587 | /* |
| 588 | * This is the real return address. Any other |
| 589 | * instances associated with this task are for |
| 590 | * other calls deeper on the call stack |
| 591 | */ |
| 592 | break; |
| 593 | } |
| 594 | |
| 595 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
| 596 | instruction_pointer(regs) = orig_ret_address; |
| 597 | |
| 598 | reset_current_kprobe(); |
| 599 | kretprobe_hash_unlock(current, &flags); |
| 600 | preempt_enable_no_resched(); |
| 601 | |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 602 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 603 | hlist_del(&ri->hlist); |
| 604 | kfree(ri); |
| 605 | } |
| 606 | /* |
| 607 | * By returning a non-zero value, we are telling |
| 608 | * kprobe_handler() that we don't want the post_handler |
| 609 | * to run (and have re-enabled preemption) |
| 610 | */ |
| 611 | return 1; |
| 612 | } |
| 613 | |
| 614 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
| 615 | { |
| 616 | if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline) |
| 617 | return 1; |
| 618 | |
| 619 | return 0; |
| 620 | } |
| 621 | |
| 622 | static struct kprobe trampoline_p = { |
| 623 | .addr = (kprobe_opcode_t *)kretprobe_trampoline, |
| 624 | .pre_handler = trampoline_probe_handler |
| 625 | }; |
| 626 | |
| 627 | int __init arch_init_kprobes(void) |
| 628 | { |
| 629 | return register_kprobe(&trampoline_p); |
| 630 | } |