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> |
| 35 | #include <asm/inst.h> |
| 36 | |
| 37 | static const union mips_instruction breakpoint_insn = { |
| 38 | .b_format = { |
| 39 | .opcode = spec_op, |
| 40 | .code = BRK_KPROBE_BP, |
| 41 | .func = break_op |
| 42 | } |
| 43 | }; |
| 44 | |
| 45 | static const union mips_instruction breakpoint2_insn = { |
| 46 | .b_format = { |
| 47 | .opcode = spec_op, |
| 48 | .code = BRK_KPROBE_SSTEPBP, |
| 49 | .func = break_op |
| 50 | } |
| 51 | }; |
| 52 | |
| 53 | DEFINE_PER_CPU(struct kprobe *, current_kprobe); |
| 54 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
| 55 | |
| 56 | static int __kprobes insn_has_delayslot(union mips_instruction insn) |
| 57 | { |
| 58 | switch (insn.i_format.opcode) { |
| 59 | |
| 60 | /* |
| 61 | * This group contains: |
| 62 | * jr and jalr are in r_format format. |
| 63 | */ |
| 64 | case spec_op: |
| 65 | switch (insn.r_format.func) { |
| 66 | case jr_op: |
| 67 | case jalr_op: |
| 68 | break; |
| 69 | default: |
| 70 | goto insn_ok; |
| 71 | } |
| 72 | |
| 73 | /* |
| 74 | * This group contains: |
| 75 | * bltz_op, bgez_op, bltzl_op, bgezl_op, |
| 76 | * bltzal_op, bgezal_op, bltzall_op, bgezall_op. |
| 77 | */ |
| 78 | case bcond_op: |
| 79 | |
| 80 | /* |
| 81 | * These are unconditional and in j_format. |
| 82 | */ |
| 83 | case jal_op: |
| 84 | case j_op: |
| 85 | |
| 86 | /* |
| 87 | * These are conditional and in i_format. |
| 88 | */ |
| 89 | case beq_op: |
| 90 | case beql_op: |
| 91 | case bne_op: |
| 92 | case bnel_op: |
| 93 | case blez_op: |
| 94 | case blezl_op: |
| 95 | case bgtz_op: |
| 96 | case bgtzl_op: |
| 97 | |
| 98 | /* |
| 99 | * These are the FPA/cp1 branch instructions. |
| 100 | */ |
| 101 | case cop1_op: |
| 102 | |
| 103 | #ifdef CONFIG_CPU_CAVIUM_OCTEON |
| 104 | case lwc2_op: /* This is bbit0 on Octeon */ |
| 105 | case ldc2_op: /* This is bbit032 on Octeon */ |
| 106 | case swc2_op: /* This is bbit1 on Octeon */ |
| 107 | case sdc2_op: /* This is bbit132 on Octeon */ |
| 108 | #endif |
| 109 | return 1; |
| 110 | default: |
| 111 | break; |
| 112 | } |
| 113 | insn_ok: |
| 114 | return 0; |
| 115 | } |
| 116 | |
Maneesh Soni | 9233c1e | 2011-11-08 17:05:35 +0530 | [diff] [blame] | 117 | /* |
| 118 | * insn_has_ll_or_sc function checks whether instruction is ll or sc |
| 119 | * one; putting breakpoint on top of atomic ll/sc pair is bad idea; |
| 120 | * so we need to prevent it and refuse kprobes insertion for such |
| 121 | * instructions; cannot do much about breakpoint in the middle of |
| 122 | * ll/sc pair; it is upto user to avoid those places |
| 123 | */ |
| 124 | static int __kprobes insn_has_ll_or_sc(union mips_instruction insn) |
| 125 | { |
| 126 | int ret = 0; |
| 127 | |
| 128 | switch (insn.i_format.opcode) { |
| 129 | case ll_op: |
| 130 | case lld_op: |
| 131 | case sc_op: |
| 132 | case scd_op: |
| 133 | ret = 1; |
| 134 | break; |
| 135 | default: |
| 136 | break; |
| 137 | } |
| 138 | return ret; |
| 139 | } |
| 140 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 141 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
| 142 | { |
| 143 | union mips_instruction insn; |
| 144 | union mips_instruction prev_insn; |
| 145 | int ret = 0; |
| 146 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 147 | insn = p->addr[0]; |
| 148 | |
Maneesh Soni | 9233c1e | 2011-11-08 17:05:35 +0530 | [diff] [blame] | 149 | if (insn_has_ll_or_sc(insn)) { |
| 150 | pr_notice("Kprobes for ll and sc instructions are not" |
| 151 | "supported\n"); |
| 152 | ret = -EINVAL; |
| 153 | goto out; |
| 154 | } |
| 155 | |
Maneesh Soni | 41dde78 | 2011-11-08 17:04:54 +0530 | [diff] [blame] | 156 | if ((probe_kernel_read(&prev_insn, p->addr - 1, |
| 157 | sizeof(mips_instruction)) == 0) && |
| 158 | insn_has_delayslot(prev_insn)) { |
| 159 | pr_notice("Kprobes for branch delayslot are not supported\n"); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 160 | ret = -EINVAL; |
| 161 | goto out; |
| 162 | } |
| 163 | |
| 164 | /* insn: must be on special executable page on mips. */ |
| 165 | p->ainsn.insn = get_insn_slot(); |
| 166 | if (!p->ainsn.insn) { |
| 167 | ret = -ENOMEM; |
| 168 | goto out; |
| 169 | } |
| 170 | |
| 171 | /* |
| 172 | * In the kprobe->ainsn.insn[] array we store the original |
| 173 | * instruction at index zero and a break trap instruction at |
| 174 | * index one. |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 175 | * |
| 176 | * On MIPS arch if the instruction at probed address is a |
| 177 | * branch instruction, we need to execute the instruction at |
| 178 | * Branch Delayslot (BD) at the time of probe hit. As MIPS also |
| 179 | * doesn't have single stepping support, the BD instruction can |
| 180 | * not be executed in-line and it would be executed on SSOL slot |
| 181 | * using a normal breakpoint instruction in the next slot. |
| 182 | * So, read the instruction and save it for later execution. |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 183 | */ |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 184 | if (insn_has_delayslot(insn)) |
| 185 | memcpy(&p->ainsn.insn[0], p->addr + 1, sizeof(kprobe_opcode_t)); |
| 186 | else |
| 187 | memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t)); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 188 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 189 | p->ainsn.insn[1] = breakpoint2_insn; |
| 190 | p->opcode = *p->addr; |
| 191 | |
| 192 | out: |
| 193 | return ret; |
| 194 | } |
| 195 | |
| 196 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
| 197 | { |
| 198 | *p->addr = breakpoint_insn; |
| 199 | flush_insn_slot(p); |
| 200 | } |
| 201 | |
| 202 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
| 203 | { |
| 204 | *p->addr = p->opcode; |
| 205 | flush_insn_slot(p); |
| 206 | } |
| 207 | |
| 208 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
| 209 | { |
Masami Hiramatsu | 22047b8 | 2013-05-22 08:34:13 +0000 | [diff] [blame] | 210 | if (p->ainsn.insn) { |
| 211 | free_insn_slot(p->ainsn.insn, 0); |
| 212 | p->ainsn.insn = NULL; |
| 213 | } |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 214 | } |
| 215 | |
| 216 | static void save_previous_kprobe(struct kprobe_ctlblk *kcb) |
| 217 | { |
| 218 | kcb->prev_kprobe.kp = kprobe_running(); |
| 219 | kcb->prev_kprobe.status = kcb->kprobe_status; |
| 220 | kcb->prev_kprobe.old_SR = kcb->kprobe_old_SR; |
| 221 | kcb->prev_kprobe.saved_SR = kcb->kprobe_saved_SR; |
| 222 | kcb->prev_kprobe.saved_epc = kcb->kprobe_saved_epc; |
| 223 | } |
| 224 | |
| 225 | static void restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
| 226 | { |
| 227 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
| 228 | kcb->kprobe_status = kcb->prev_kprobe.status; |
| 229 | kcb->kprobe_old_SR = kcb->prev_kprobe.old_SR; |
| 230 | kcb->kprobe_saved_SR = kcb->prev_kprobe.saved_SR; |
| 231 | kcb->kprobe_saved_epc = kcb->prev_kprobe.saved_epc; |
| 232 | } |
| 233 | |
| 234 | static void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
| 235 | struct kprobe_ctlblk *kcb) |
| 236 | { |
| 237 | __get_cpu_var(current_kprobe) = p; |
| 238 | kcb->kprobe_saved_SR = kcb->kprobe_old_SR = (regs->cp0_status & ST0_IE); |
| 239 | kcb->kprobe_saved_epc = regs->cp0_epc; |
| 240 | } |
| 241 | |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 242 | /** |
| 243 | * evaluate_branch_instrucion - |
| 244 | * |
| 245 | * Evaluate the branch instruction at probed address during probe hit. The |
| 246 | * result of evaluation would be the updated epc. The insturction in delayslot |
| 247 | * would actually be single stepped using a normal breakpoint) on SSOL slot. |
| 248 | * |
| 249 | * The result is also saved in the kprobe control block for later use, |
| 250 | * in case we need to execute the delayslot instruction. The latter will be |
| 251 | * false for NOP instruction in dealyslot and the branch-likely instructions |
| 252 | * when the branch is taken. And for those cases we set a flag as |
| 253 | * SKIP_DELAYSLOT in the kprobe control block |
| 254 | */ |
| 255 | static int evaluate_branch_instruction(struct kprobe *p, struct pt_regs *regs, |
| 256 | struct kprobe_ctlblk *kcb) |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 257 | { |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 258 | union mips_instruction insn = p->opcode; |
| 259 | long epc; |
| 260 | int ret = 0; |
| 261 | |
| 262 | epc = regs->cp0_epc; |
| 263 | if (epc & 3) |
| 264 | goto unaligned; |
| 265 | |
| 266 | if (p->ainsn.insn->word == 0) |
| 267 | kcb->flags |= SKIP_DELAYSLOT; |
| 268 | else |
| 269 | kcb->flags &= ~SKIP_DELAYSLOT; |
| 270 | |
| 271 | ret = __compute_return_epc_for_insn(regs, insn); |
| 272 | if (ret < 0) |
| 273 | return ret; |
| 274 | |
| 275 | if (ret == BRANCH_LIKELY_TAKEN) |
| 276 | kcb->flags |= SKIP_DELAYSLOT; |
| 277 | |
| 278 | kcb->target_epc = regs->cp0_epc; |
| 279 | |
| 280 | return 0; |
| 281 | |
| 282 | unaligned: |
| 283 | pr_notice("%s: unaligned epc - sending SIGBUS.\n", current->comm); |
| 284 | force_sig(SIGBUS, current); |
| 285 | return -EFAULT; |
| 286 | |
| 287 | } |
| 288 | |
| 289 | static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs, |
| 290 | struct kprobe_ctlblk *kcb) |
| 291 | { |
| 292 | int ret = 0; |
| 293 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 294 | regs->cp0_status &= ~ST0_IE; |
| 295 | |
| 296 | /* single step inline if the instruction is a break */ |
| 297 | if (p->opcode.word == breakpoint_insn.word || |
| 298 | p->opcode.word == breakpoint2_insn.word) |
| 299 | regs->cp0_epc = (unsigned long)p->addr; |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 300 | else if (insn_has_delayslot(p->opcode)) { |
| 301 | ret = evaluate_branch_instruction(p, regs, kcb); |
| 302 | if (ret < 0) { |
| 303 | pr_notice("Kprobes: Error in evaluating branch\n"); |
| 304 | return; |
| 305 | } |
| 306 | } |
| 307 | regs->cp0_epc = (unsigned long)&p->ainsn.insn[0]; |
| 308 | } |
| 309 | |
| 310 | /* |
| 311 | * Called after single-stepping. p->addr is the address of the |
| 312 | * instruction whose first byte has been replaced by the "break 0" |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 313 | * instruction. To avoid the SMP problems that can occur when we |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 314 | * temporarily put back the original opcode to single-step, we |
| 315 | * single-stepped a copy of the instruction. The address of this |
| 316 | * copy is p->ainsn.insn. |
| 317 | * |
| 318 | * This function prepares to return from the post-single-step |
| 319 | * breakpoint trap. In case of branch instructions, the target |
| 320 | * epc to be restored. |
| 321 | */ |
| 322 | static void __kprobes resume_execution(struct kprobe *p, |
| 323 | struct pt_regs *regs, |
| 324 | struct kprobe_ctlblk *kcb) |
| 325 | { |
| 326 | if (insn_has_delayslot(p->opcode)) |
| 327 | regs->cp0_epc = kcb->target_epc; |
| 328 | else { |
| 329 | unsigned long orig_epc = kcb->kprobe_saved_epc; |
| 330 | regs->cp0_epc = orig_epc + 4; |
| 331 | } |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 332 | } |
| 333 | |
| 334 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
| 335 | { |
| 336 | struct kprobe *p; |
| 337 | int ret = 0; |
| 338 | kprobe_opcode_t *addr; |
| 339 | struct kprobe_ctlblk *kcb; |
| 340 | |
| 341 | addr = (kprobe_opcode_t *) regs->cp0_epc; |
| 342 | |
| 343 | /* |
| 344 | * We don't want to be preempted for the entire |
| 345 | * duration of kprobe processing |
| 346 | */ |
| 347 | preempt_disable(); |
| 348 | kcb = get_kprobe_ctlblk(); |
| 349 | |
| 350 | /* Check we're not actually recursing */ |
| 351 | if (kprobe_running()) { |
| 352 | p = get_kprobe(addr); |
| 353 | if (p) { |
| 354 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
| 355 | p->ainsn.insn->word == breakpoint_insn.word) { |
| 356 | regs->cp0_status &= ~ST0_IE; |
| 357 | regs->cp0_status |= kcb->kprobe_saved_SR; |
| 358 | goto no_kprobe; |
| 359 | } |
| 360 | /* |
| 361 | * We have reentered the kprobe_handler(), since |
| 362 | * another probe was hit while within the handler. |
| 363 | * We here save the original kprobes variables and |
| 364 | * just single step on the instruction of the new probe |
| 365 | * without calling any user handlers. |
| 366 | */ |
| 367 | save_previous_kprobe(kcb); |
| 368 | set_current_kprobe(p, regs, kcb); |
| 369 | kprobes_inc_nmissed_count(p); |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 370 | prepare_singlestep(p, regs, kcb); |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 371 | kcb->kprobe_status = KPROBE_REENTER; |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 372 | if (kcb->flags & SKIP_DELAYSLOT) { |
| 373 | resume_execution(p, regs, kcb); |
| 374 | restore_previous_kprobe(kcb); |
| 375 | preempt_enable_no_resched(); |
| 376 | } |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 377 | return 1; |
| 378 | } else { |
| 379 | if (addr->word != breakpoint_insn.word) { |
| 380 | /* |
| 381 | * The breakpoint instruction was removed by |
| 382 | * another cpu right after we hit, no further |
| 383 | * handling of this interrupt is appropriate |
| 384 | */ |
| 385 | ret = 1; |
| 386 | goto no_kprobe; |
| 387 | } |
| 388 | p = __get_cpu_var(current_kprobe); |
| 389 | if (p->break_handler && p->break_handler(p, regs)) |
| 390 | goto ss_probe; |
| 391 | } |
| 392 | goto no_kprobe; |
| 393 | } |
| 394 | |
| 395 | p = get_kprobe(addr); |
| 396 | if (!p) { |
| 397 | if (addr->word != breakpoint_insn.word) { |
| 398 | /* |
| 399 | * The breakpoint instruction was removed right |
| 400 | * after we hit it. Another cpu has removed |
| 401 | * either a probepoint or a debugger breakpoint |
| 402 | * at this address. In either case, no further |
| 403 | * handling of this interrupt is appropriate. |
| 404 | */ |
| 405 | ret = 1; |
| 406 | } |
| 407 | /* Not one of ours: let kernel handle it */ |
| 408 | goto no_kprobe; |
| 409 | } |
| 410 | |
| 411 | set_current_kprobe(p, regs, kcb); |
| 412 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| 413 | |
| 414 | if (p->pre_handler && p->pre_handler(p, regs)) { |
| 415 | /* handler has already set things up, so skip ss setup */ |
| 416 | return 1; |
| 417 | } |
| 418 | |
| 419 | ss_probe: |
Maneesh Soni | 6457a39 | 2011-11-08 17:08:26 +0530 | [diff] [blame] | 420 | prepare_singlestep(p, regs, kcb); |
| 421 | if (kcb->flags & SKIP_DELAYSLOT) { |
| 422 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 423 | if (p->post_handler) |
| 424 | p->post_handler(p, regs, 0); |
| 425 | resume_execution(p, regs, kcb); |
| 426 | preempt_enable_no_resched(); |
| 427 | } else |
| 428 | kcb->kprobe_status = KPROBE_HIT_SS; |
| 429 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 430 | return 1; |
| 431 | |
| 432 | no_kprobe: |
| 433 | preempt_enable_no_resched(); |
| 434 | return ret; |
| 435 | |
| 436 | } |
| 437 | |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 438 | static inline int post_kprobe_handler(struct pt_regs *regs) |
| 439 | { |
| 440 | struct kprobe *cur = kprobe_running(); |
| 441 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 442 | |
| 443 | if (!cur) |
| 444 | return 0; |
| 445 | |
| 446 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
| 447 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 448 | cur->post_handler(cur, regs, 0); |
| 449 | } |
| 450 | |
| 451 | resume_execution(cur, regs, kcb); |
| 452 | |
| 453 | regs->cp0_status |= kcb->kprobe_saved_SR; |
| 454 | |
| 455 | /* Restore back the original saved kprobes variables and continue. */ |
| 456 | if (kcb->kprobe_status == KPROBE_REENTER) { |
| 457 | restore_previous_kprobe(kcb); |
| 458 | goto out; |
| 459 | } |
| 460 | reset_current_kprobe(); |
| 461 | out: |
| 462 | preempt_enable_no_resched(); |
| 463 | |
| 464 | return 1; |
| 465 | } |
| 466 | |
| 467 | static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
| 468 | { |
| 469 | struct kprobe *cur = kprobe_running(); |
| 470 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 471 | |
| 472 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) |
| 473 | return 1; |
| 474 | |
| 475 | if (kcb->kprobe_status & KPROBE_HIT_SS) { |
| 476 | resume_execution(cur, regs, kcb); |
| 477 | regs->cp0_status |= kcb->kprobe_old_SR; |
| 478 | |
| 479 | reset_current_kprobe(); |
| 480 | preempt_enable_no_resched(); |
| 481 | } |
| 482 | return 0; |
| 483 | } |
| 484 | |
| 485 | /* |
| 486 | * Wrapper routine for handling exceptions. |
| 487 | */ |
| 488 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
| 489 | unsigned long val, void *data) |
| 490 | { |
| 491 | |
| 492 | struct die_args *args = (struct die_args *)data; |
| 493 | int ret = NOTIFY_DONE; |
| 494 | |
| 495 | switch (val) { |
| 496 | case DIE_BREAK: |
| 497 | if (kprobe_handler(args->regs)) |
| 498 | ret = NOTIFY_STOP; |
| 499 | break; |
| 500 | case DIE_SSTEPBP: |
| 501 | if (post_kprobe_handler(args->regs)) |
| 502 | ret = NOTIFY_STOP; |
| 503 | break; |
| 504 | |
| 505 | case DIE_PAGE_FAULT: |
| 506 | /* kprobe_running() needs smp_processor_id() */ |
| 507 | preempt_disable(); |
| 508 | |
| 509 | if (kprobe_running() |
| 510 | && kprobe_fault_handler(args->regs, args->trapnr)) |
| 511 | ret = NOTIFY_STOP; |
| 512 | preempt_enable(); |
| 513 | break; |
| 514 | default: |
| 515 | break; |
| 516 | } |
| 517 | return ret; |
| 518 | } |
| 519 | |
| 520 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
| 521 | { |
| 522 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 523 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 524 | |
| 525 | kcb->jprobe_saved_regs = *regs; |
| 526 | kcb->jprobe_saved_sp = regs->regs[29]; |
| 527 | |
| 528 | memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp, |
| 529 | MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); |
| 530 | |
| 531 | regs->cp0_epc = (unsigned long)(jp->entry); |
| 532 | |
| 533 | return 1; |
| 534 | } |
| 535 | |
| 536 | /* Defined in the inline asm below. */ |
| 537 | void jprobe_return_end(void); |
| 538 | |
| 539 | void __kprobes jprobe_return(void) |
| 540 | { |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 541 | /* Assembler quirk necessitates this '0,code' business. */ |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 542 | asm volatile( |
| 543 | "break 0,%0\n\t" |
| 544 | ".globl jprobe_return_end\n" |
| 545 | "jprobe_return_end:\n" |
| 546 | : : "n" (BRK_KPROBE_BP) : "memory"); |
| 547 | } |
| 548 | |
| 549 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
| 550 | { |
| 551 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 552 | |
| 553 | if (regs->cp0_epc >= (unsigned long)jprobe_return && |
| 554 | regs->cp0_epc <= (unsigned long)jprobe_return_end) { |
| 555 | *regs = kcb->jprobe_saved_regs; |
| 556 | memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack, |
| 557 | MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp)); |
| 558 | preempt_enable_no_resched(); |
| 559 | |
| 560 | return 1; |
| 561 | } |
| 562 | return 0; |
| 563 | } |
| 564 | |
| 565 | /* |
| 566 | * Function return probe trampoline: |
| 567 | * - init_kprobes() establishes a probepoint here |
| 568 | * - When the probed function returns, this probe causes the |
| 569 | * handlers to fire |
| 570 | */ |
| 571 | static void __used kretprobe_trampoline_holder(void) |
| 572 | { |
| 573 | asm volatile( |
| 574 | ".set push\n\t" |
| 575 | /* Keep the assembler from reordering and placing JR here. */ |
| 576 | ".set noreorder\n\t" |
| 577 | "nop\n\t" |
| 578 | ".global kretprobe_trampoline\n" |
| 579 | "kretprobe_trampoline:\n\t" |
| 580 | "nop\n\t" |
| 581 | ".set pop" |
| 582 | : : : "memory"); |
| 583 | } |
| 584 | |
| 585 | void kretprobe_trampoline(void); |
| 586 | |
| 587 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
| 588 | struct pt_regs *regs) |
| 589 | { |
| 590 | ri->ret_addr = (kprobe_opcode_t *) regs->regs[31]; |
| 591 | |
| 592 | /* Replace the return addr with trampoline addr */ |
| 593 | regs->regs[31] = (unsigned long)kretprobe_trampoline; |
| 594 | } |
| 595 | |
| 596 | /* |
| 597 | * Called when the probe at kretprobe trampoline is hit |
| 598 | */ |
| 599 | static int __kprobes trampoline_probe_handler(struct kprobe *p, |
| 600 | struct pt_regs *regs) |
| 601 | { |
| 602 | struct kretprobe_instance *ri = NULL; |
| 603 | struct hlist_head *head, empty_rp; |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 604 | struct hlist_node *tmp; |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 605 | unsigned long flags, orig_ret_address = 0; |
| 606 | unsigned long trampoline_address = (unsigned long)kretprobe_trampoline; |
| 607 | |
| 608 | INIT_HLIST_HEAD(&empty_rp); |
| 609 | kretprobe_hash_lock(current, &head, &flags); |
| 610 | |
| 611 | /* |
| 612 | * It is possible to have multiple instances associated with a given |
| 613 | * task either because an multiple functions in the call path |
| 614 | * have a return probe installed on them, and/or more than one return |
| 615 | * return probe was registered for a target function. |
| 616 | * |
| 617 | * We can handle this because: |
| 618 | * - instances are always inserted at the head of the list |
| 619 | * - when multiple return probes are registered for the same |
Ralf Baechle | 7034228 | 2013-01-22 12:59:30 +0100 | [diff] [blame] | 620 | * function, the first instance's ret_addr will point to the |
| 621 | * real return address, and all the rest will point to |
| 622 | * kretprobe_trampoline |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 623 | */ |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 624 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 625 | if (ri->task != current) |
| 626 | /* another task is sharing our hash bucket */ |
| 627 | continue; |
| 628 | |
| 629 | if (ri->rp && ri->rp->handler) |
| 630 | ri->rp->handler(ri, regs); |
| 631 | |
| 632 | orig_ret_address = (unsigned long)ri->ret_addr; |
| 633 | recycle_rp_inst(ri, &empty_rp); |
| 634 | |
| 635 | if (orig_ret_address != trampoline_address) |
| 636 | /* |
| 637 | * This is the real return address. Any other |
| 638 | * instances associated with this task are for |
| 639 | * other calls deeper on the call stack |
| 640 | */ |
| 641 | break; |
| 642 | } |
| 643 | |
| 644 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
| 645 | instruction_pointer(regs) = orig_ret_address; |
| 646 | |
| 647 | reset_current_kprobe(); |
| 648 | kretprobe_hash_unlock(current, &flags); |
| 649 | preempt_enable_no_resched(); |
| 650 | |
Sasha Levin | b67bfe0 | 2013-02-27 17:06:00 -0800 | [diff] [blame] | 651 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
David Daney | c1bf207 | 2010-08-03 11:22:20 -0700 | [diff] [blame] | 652 | hlist_del(&ri->hlist); |
| 653 | kfree(ri); |
| 654 | } |
| 655 | /* |
| 656 | * By returning a non-zero value, we are telling |
| 657 | * kprobe_handler() that we don't want the post_handler |
| 658 | * to run (and have re-enabled preemption) |
| 659 | */ |
| 660 | return 1; |
| 661 | } |
| 662 | |
| 663 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
| 664 | { |
| 665 | if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline) |
| 666 | return 1; |
| 667 | |
| 668 | return 0; |
| 669 | } |
| 670 | |
| 671 | static struct kprobe trampoline_p = { |
| 672 | .addr = (kprobe_opcode_t *)kretprobe_trampoline, |
| 673 | .pre_handler = trampoline_probe_handler |
| 674 | }; |
| 675 | |
| 676 | int __init arch_init_kprobes(void) |
| 677 | { |
| 678 | return register_kprobe(&trampoline_p); |
| 679 | } |