1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Code for replacing ftrace calls with jumps. 4 * 5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> 6 * 7 * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box. 8 * 9 * Added function graph tracer code, taken from x86 that was written 10 * by Frederic Weisbecker, and ported to PPC by Steven Rostedt. 11 * 12 */ 13 14 #define pr_fmt(fmt) "ftrace-powerpc: " fmt 15 16 #include <linux/spinlock.h> 17 #include <linux/hardirq.h> 18 #include <linux/uaccess.h> 19 #include <linux/module.h> 20 #include <linux/ftrace.h> 21 #include <linux/percpu.h> 22 #include <linux/init.h> 23 #include <linux/list.h> 24 25 #include <asm/cacheflush.h> 26 #include <asm/code-patching.h> 27 #include <asm/ftrace.h> 28 #include <asm/syscall.h> 29 #include <asm/inst.h> 30 31 /* 32 * We generally only have a single long_branch tramp and at most 2 or 3 plt 33 * tramps generated. But, we don't use the plt tramps currently. We also allot 34 * 2 tramps after .text and .init.text. So, we only end up with around 3 usable 35 * tramps in total. Set aside 8 just to be sure. 36 */ 37 #define NUM_FTRACE_TRAMPS 8 38 static unsigned long ftrace_tramps[NUM_FTRACE_TRAMPS]; 39 40 static ppc_inst_t 41 ftrace_call_replace(unsigned long ip, unsigned long addr, int link) 42 { 43 ppc_inst_t op; 44 45 addr = ppc_function_entry((void *)addr); 46 47 /* if (link) set op to 'bl' else 'b' */ 48 create_branch(&op, (u32 *)ip, addr, link ? BRANCH_SET_LINK : 0); 49 50 return op; 51 } 52 53 static inline int 54 ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) 55 { 56 ppc_inst_t replaced; 57 58 /* 59 * Note: 60 * We are paranoid about modifying text, as if a bug was to happen, it 61 * could cause us to read or write to someplace that could cause harm. 62 * Carefully read and modify the code with probe_kernel_*(), and make 63 * sure what we read is what we expected it to be before modifying it. 64 */ 65 66 /* read the text we want to modify */ 67 if (copy_inst_from_kernel_nofault(&replaced, (void *)ip)) 68 return -EFAULT; 69 70 /* Make sure it is what we expect it to be */ 71 if (!ppc_inst_equal(replaced, old)) { 72 pr_err("%p: replaced (%08lx) != old (%08lx)", (void *)ip, 73 ppc_inst_as_ulong(replaced), ppc_inst_as_ulong(old)); 74 return -EINVAL; 75 } 76 77 /* replace the text with the new text */ 78 return patch_instruction((u32 *)ip, new); 79 } 80 81 /* 82 * Helper functions that are the same for both PPC64 and PPC32. 83 */ 84 static int test_24bit_addr(unsigned long ip, unsigned long addr) 85 { 86 addr = ppc_function_entry((void *)addr); 87 88 return is_offset_in_branch_range(addr - ip); 89 } 90 91 static int is_bl_op(ppc_inst_t op) 92 { 93 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BL(0); 94 } 95 96 static int is_b_op(ppc_inst_t op) 97 { 98 return (ppc_inst_val(op) & ~PPC_LI_MASK) == PPC_RAW_BRANCH(0); 99 } 100 101 static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op) 102 { 103 int offset; 104 105 offset = PPC_LI(ppc_inst_val(op)); 106 /* make it signed */ 107 if (offset & 0x02000000) 108 offset |= 0xfe000000; 109 110 return ip + (long)offset; 111 } 112 113 #ifdef CONFIG_MODULES 114 static int 115 __ftrace_make_nop(struct module *mod, 116 struct dyn_ftrace *rec, unsigned long addr) 117 { 118 unsigned long entry, ptr, tramp; 119 unsigned long ip = rec->ip; 120 ppc_inst_t op, pop; 121 122 /* read where this goes */ 123 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { 124 pr_err("Fetching opcode failed.\n"); 125 return -EFAULT; 126 } 127 128 /* Make sure that this is still a 24bit jump */ 129 if (!is_bl_op(op)) { 130 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); 131 return -EINVAL; 132 } 133 134 /* lets find where the pointer goes */ 135 tramp = find_bl_target(ip, op); 136 137 pr_devel("ip:%lx jumps to %lx", ip, tramp); 138 139 if (module_trampoline_target(mod, tramp, &ptr)) { 140 pr_err("Failed to get trampoline target\n"); 141 return -EFAULT; 142 } 143 144 pr_devel("trampoline target %lx", ptr); 145 146 entry = ppc_global_function_entry((void *)addr); 147 /* This should match what was called */ 148 if (ptr != entry) { 149 pr_err("addr %lx does not match expected %lx\n", ptr, entry); 150 return -EINVAL; 151 } 152 153 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL)) { 154 if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) { 155 pr_err("Fetching instruction at %lx failed.\n", ip - 4); 156 return -EFAULT; 157 } 158 159 /* We expect either a mflr r0, or a std r0, LRSAVE(r1) */ 160 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_MFLR(_R0))) && 161 !ppc_inst_equal(op, ppc_inst(PPC_INST_STD_LR))) { 162 pr_err("Unexpected instruction %08lx around bl _mcount\n", 163 ppc_inst_as_ulong(op)); 164 return -EINVAL; 165 } 166 } else if (IS_ENABLED(CONFIG_PPC64)) { 167 /* 168 * Check what is in the next instruction. We can see ld r2,40(r1), but 169 * on first pass after boot we will see mflr r0. 170 */ 171 if (copy_inst_from_kernel_nofault(&op, (void *)(ip + 4))) { 172 pr_err("Fetching op failed.\n"); 173 return -EFAULT; 174 } 175 176 if (!ppc_inst_equal(op, ppc_inst(PPC_INST_LD_TOC))) { 177 pr_err("Expected %08lx found %08lx\n", PPC_INST_LD_TOC, 178 ppc_inst_as_ulong(op)); 179 return -EINVAL; 180 } 181 } 182 183 /* 184 * When using -mprofile-kernel or PPC32 there is no load to jump over. 185 * 186 * Otherwise our original call site looks like: 187 * 188 * bl <tramp> 189 * ld r2,XX(r1) 190 * 191 * Milton Miller pointed out that we can not simply nop the branch. 192 * If a task was preempted when calling a trace function, the nops 193 * will remove the way to restore the TOC in r2 and the r2 TOC will 194 * get corrupted. 195 * 196 * Use a b +8 to jump over the load. 197 */ 198 if (IS_ENABLED(CONFIG_MPROFILE_KERNEL) || IS_ENABLED(CONFIG_PPC32)) 199 pop = ppc_inst(PPC_RAW_NOP()); 200 else 201 pop = ppc_inst(PPC_RAW_BRANCH(8)); /* b +8 */ 202 203 if (patch_instruction((u32 *)ip, pop)) { 204 pr_err("Patching NOP failed.\n"); 205 return -EPERM; 206 } 207 208 return 0; 209 } 210 #else 211 static int __ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) 212 { 213 return 0; 214 } 215 #endif /* CONFIG_MODULES */ 216 217 static unsigned long find_ftrace_tramp(unsigned long ip) 218 { 219 int i; 220 221 /* 222 * We have the compiler generated long_branch tramps at the end 223 * and we prefer those 224 */ 225 for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--) 226 if (!ftrace_tramps[i]) 227 continue; 228 else if (is_offset_in_branch_range(ftrace_tramps[i] - ip)) 229 return ftrace_tramps[i]; 230 231 return 0; 232 } 233 234 static int add_ftrace_tramp(unsigned long tramp) 235 { 236 int i; 237 238 for (i = 0; i < NUM_FTRACE_TRAMPS; i++) 239 if (!ftrace_tramps[i]) { 240 ftrace_tramps[i] = tramp; 241 return 0; 242 } 243 244 return -1; 245 } 246 247 /* 248 * If this is a compiler generated long_branch trampoline (essentially, a 249 * trampoline that has a branch to _mcount()), we re-write the branch to 250 * instead go to ftrace_[regs_]caller() and note down the location of this 251 * trampoline. 252 */ 253 static int setup_mcount_compiler_tramp(unsigned long tramp) 254 { 255 int i; 256 ppc_inst_t op; 257 unsigned long ptr; 258 259 /* Is this a known long jump tramp? */ 260 for (i = 0; i < NUM_FTRACE_TRAMPS; i++) 261 if (ftrace_tramps[i] == tramp) 262 return 0; 263 264 /* New trampoline -- read where this goes */ 265 if (copy_inst_from_kernel_nofault(&op, (void *)tramp)) { 266 pr_debug("Fetching opcode failed.\n"); 267 return -1; 268 } 269 270 /* Is this a 24 bit branch? */ 271 if (!is_b_op(op)) { 272 pr_debug("Trampoline is not a long branch tramp.\n"); 273 return -1; 274 } 275 276 /* lets find where the pointer goes */ 277 ptr = find_bl_target(tramp, op); 278 279 if (ptr != ppc_global_function_entry((void *)_mcount)) { 280 pr_debug("Trampoline target %p is not _mcount\n", (void *)ptr); 281 return -1; 282 } 283 284 /* Let's re-write the tramp to go to ftrace_[regs_]caller */ 285 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) 286 ptr = ppc_global_function_entry((void *)ftrace_regs_caller); 287 else 288 ptr = ppc_global_function_entry((void *)ftrace_caller); 289 290 if (patch_branch((u32 *)tramp, ptr, 0)) { 291 pr_debug("REL24 out of range!\n"); 292 return -1; 293 } 294 295 if (add_ftrace_tramp(tramp)) { 296 pr_debug("No tramp locations left\n"); 297 return -1; 298 } 299 300 return 0; 301 } 302 303 static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr) 304 { 305 unsigned long tramp, ip = rec->ip; 306 ppc_inst_t op; 307 308 /* Read where this goes */ 309 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { 310 pr_err("Fetching opcode failed.\n"); 311 return -EFAULT; 312 } 313 314 /* Make sure that this is still a 24bit jump */ 315 if (!is_bl_op(op)) { 316 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); 317 return -EINVAL; 318 } 319 320 /* Let's find where the pointer goes */ 321 tramp = find_bl_target(ip, op); 322 323 pr_devel("ip:%lx jumps to %lx", ip, tramp); 324 325 if (setup_mcount_compiler_tramp(tramp)) { 326 /* Are other trampolines reachable? */ 327 if (!find_ftrace_tramp(ip)) { 328 pr_err("No ftrace trampolines reachable from %ps\n", 329 (void *)ip); 330 return -EINVAL; 331 } 332 } 333 334 if (patch_instruction((u32 *)ip, ppc_inst(PPC_RAW_NOP()))) { 335 pr_err("Patching NOP failed.\n"); 336 return -EPERM; 337 } 338 339 return 0; 340 } 341 342 int ftrace_make_nop(struct module *mod, 343 struct dyn_ftrace *rec, unsigned long addr) 344 { 345 unsigned long ip = rec->ip; 346 ppc_inst_t old, new; 347 348 /* 349 * If the calling address is more that 24 bits away, 350 * then we had to use a trampoline to make the call. 351 * Otherwise just update the call site. 352 */ 353 if (test_24bit_addr(ip, addr)) { 354 /* within range */ 355 old = ftrace_call_replace(ip, addr, 1); 356 new = ppc_inst(PPC_RAW_NOP()); 357 return ftrace_modify_code(ip, old, new); 358 } else if (core_kernel_text(ip)) { 359 return __ftrace_make_nop_kernel(rec, addr); 360 } else if (!IS_ENABLED(CONFIG_MODULES)) { 361 return -EINVAL; 362 } 363 364 /* 365 * Out of range jumps are called from modules. 366 * We should either already have a pointer to the module 367 * or it has been passed in. 368 */ 369 if (!rec->arch.mod) { 370 if (!mod) { 371 pr_err("No module loaded addr=%lx\n", addr); 372 return -EFAULT; 373 } 374 rec->arch.mod = mod; 375 } else if (mod) { 376 if (mod != rec->arch.mod) { 377 pr_err("Record mod %p not equal to passed in mod %p\n", 378 rec->arch.mod, mod); 379 return -EINVAL; 380 } 381 /* nothing to do if mod == rec->arch.mod */ 382 } else 383 mod = rec->arch.mod; 384 385 return __ftrace_make_nop(mod, rec, addr); 386 } 387 388 #ifdef CONFIG_MODULES 389 /* 390 * Examine the existing instructions for __ftrace_make_call. 391 * They should effectively be a NOP, and follow formal constraints, 392 * depending on the ABI. Return false if they don't. 393 */ 394 static bool expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1) 395 { 396 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) 397 return ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP())); 398 else 399 return ppc_inst_equal(op0, ppc_inst(PPC_RAW_BRANCH(8))) && 400 ppc_inst_equal(op1, ppc_inst(PPC_INST_LD_TOC)); 401 } 402 403 static int 404 __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 405 { 406 ppc_inst_t op[2]; 407 void *ip = (void *)rec->ip; 408 unsigned long entry, ptr, tramp; 409 struct module *mod = rec->arch.mod; 410 411 /* read where this goes */ 412 if (copy_inst_from_kernel_nofault(op, ip)) 413 return -EFAULT; 414 415 if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && 416 copy_inst_from_kernel_nofault(op + 1, ip + 4)) 417 return -EFAULT; 418 419 if (!expected_nop_sequence(ip, op[0], op[1])) { 420 pr_err("Unexpected call sequence at %p: %08lx %08lx\n", ip, 421 ppc_inst_as_ulong(op[0]), ppc_inst_as_ulong(op[1])); 422 return -EINVAL; 423 } 424 425 /* If we never set up ftrace trampoline(s), then bail */ 426 if (!mod->arch.tramp || 427 (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !mod->arch.tramp_regs)) { 428 pr_err("No ftrace trampoline\n"); 429 return -EINVAL; 430 } 431 432 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && rec->flags & FTRACE_FL_REGS) 433 tramp = mod->arch.tramp_regs; 434 else 435 tramp = mod->arch.tramp; 436 437 if (module_trampoline_target(mod, tramp, &ptr)) { 438 pr_err("Failed to get trampoline target\n"); 439 return -EFAULT; 440 } 441 442 pr_devel("trampoline target %lx", ptr); 443 444 entry = ppc_global_function_entry((void *)addr); 445 /* This should match what was called */ 446 if (ptr != entry) { 447 pr_err("addr %lx does not match expected %lx\n", ptr, entry); 448 return -EINVAL; 449 } 450 451 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { 452 pr_err("REL24 out of range!\n"); 453 return -EINVAL; 454 } 455 456 return 0; 457 } 458 #else 459 static int __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 460 { 461 return 0; 462 } 463 #endif /* CONFIG_MODULES */ 464 465 static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr) 466 { 467 ppc_inst_t op; 468 void *ip = (void *)rec->ip; 469 unsigned long tramp, entry, ptr; 470 471 /* Make sure we're being asked to patch branch to a known ftrace addr */ 472 entry = ppc_global_function_entry((void *)ftrace_caller); 473 ptr = ppc_global_function_entry((void *)addr); 474 475 if (ptr != entry && IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) 476 entry = ppc_global_function_entry((void *)ftrace_regs_caller); 477 478 if (ptr != entry) { 479 pr_err("Unknown ftrace addr to patch: %ps\n", (void *)ptr); 480 return -EINVAL; 481 } 482 483 /* Make sure we have a nop */ 484 if (copy_inst_from_kernel_nofault(&op, ip)) { 485 pr_err("Unable to read ftrace location %p\n", ip); 486 return -EFAULT; 487 } 488 489 if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) { 490 pr_err("Unexpected call sequence at %p: %08lx\n", 491 ip, ppc_inst_as_ulong(op)); 492 return -EINVAL; 493 } 494 495 tramp = find_ftrace_tramp((unsigned long)ip); 496 if (!tramp) { 497 pr_err("No ftrace trampolines reachable from %ps\n", ip); 498 return -EINVAL; 499 } 500 501 if (patch_branch(ip, tramp, BRANCH_SET_LINK)) { 502 pr_err("Error patching branch to ftrace tramp!\n"); 503 return -EINVAL; 504 } 505 506 return 0; 507 } 508 509 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 510 { 511 unsigned long ip = rec->ip; 512 ppc_inst_t old, new; 513 514 /* 515 * If the calling address is more that 24 bits away, 516 * then we had to use a trampoline to make the call. 517 * Otherwise just update the call site. 518 */ 519 if (test_24bit_addr(ip, addr)) { 520 /* within range */ 521 old = ppc_inst(PPC_RAW_NOP()); 522 new = ftrace_call_replace(ip, addr, 1); 523 return ftrace_modify_code(ip, old, new); 524 } else if (core_kernel_text(ip)) { 525 return __ftrace_make_call_kernel(rec, addr); 526 } else if (!IS_ENABLED(CONFIG_MODULES)) { 527 /* We should not get here without modules */ 528 return -EINVAL; 529 } 530 531 /* 532 * Out of range jumps are called from modules. 533 * Being that we are converting from nop, it had better 534 * already have a module defined. 535 */ 536 if (!rec->arch.mod) { 537 pr_err("No module loaded\n"); 538 return -EINVAL; 539 } 540 541 return __ftrace_make_call(rec, addr); 542 } 543 544 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS 545 #ifdef CONFIG_MODULES 546 static int 547 __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 548 unsigned long addr) 549 { 550 ppc_inst_t op; 551 unsigned long ip = rec->ip; 552 unsigned long entry, ptr, tramp; 553 struct module *mod = rec->arch.mod; 554 555 /* If we never set up ftrace trampolines, then bail */ 556 if (!mod->arch.tramp || !mod->arch.tramp_regs) { 557 pr_err("No ftrace trampoline\n"); 558 return -EINVAL; 559 } 560 561 /* read where this goes */ 562 if (copy_inst_from_kernel_nofault(&op, (void *)ip)) { 563 pr_err("Fetching opcode failed.\n"); 564 return -EFAULT; 565 } 566 567 /* Make sure that this is still a 24bit jump */ 568 if (!is_bl_op(op)) { 569 pr_err("Not expected bl: opcode is %08lx\n", ppc_inst_as_ulong(op)); 570 return -EINVAL; 571 } 572 573 /* lets find where the pointer goes */ 574 tramp = find_bl_target(ip, op); 575 entry = ppc_global_function_entry((void *)old_addr); 576 577 pr_devel("ip:%lx jumps to %lx", ip, tramp); 578 579 if (tramp != entry) { 580 /* old_addr is not within range, so we must have used a trampoline */ 581 if (module_trampoline_target(mod, tramp, &ptr)) { 582 pr_err("Failed to get trampoline target\n"); 583 return -EFAULT; 584 } 585 586 pr_devel("trampoline target %lx", ptr); 587 588 /* This should match what was called */ 589 if (ptr != entry) { 590 pr_err("addr %lx does not match expected %lx\n", ptr, entry); 591 return -EINVAL; 592 } 593 } 594 595 /* The new target may be within range */ 596 if (test_24bit_addr(ip, addr)) { 597 /* within range */ 598 if (patch_branch((u32 *)ip, addr, BRANCH_SET_LINK)) { 599 pr_err("REL24 out of range!\n"); 600 return -EINVAL; 601 } 602 603 return 0; 604 } 605 606 if (rec->flags & FTRACE_FL_REGS) 607 tramp = mod->arch.tramp_regs; 608 else 609 tramp = mod->arch.tramp; 610 611 if (module_trampoline_target(mod, tramp, &ptr)) { 612 pr_err("Failed to get trampoline target\n"); 613 return -EFAULT; 614 } 615 616 pr_devel("trampoline target %lx", ptr); 617 618 entry = ppc_global_function_entry((void *)addr); 619 /* This should match what was called */ 620 if (ptr != entry) { 621 pr_err("addr %lx does not match expected %lx\n", ptr, entry); 622 return -EINVAL; 623 } 624 625 if (patch_branch((u32 *)ip, tramp, BRANCH_SET_LINK)) { 626 pr_err("REL24 out of range!\n"); 627 return -EINVAL; 628 } 629 630 return 0; 631 } 632 #else 633 static int __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) 634 { 635 return 0; 636 } 637 #endif 638 639 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 640 unsigned long addr) 641 { 642 unsigned long ip = rec->ip; 643 ppc_inst_t old, new; 644 645 /* 646 * If the calling address is more that 24 bits away, 647 * then we had to use a trampoline to make the call. 648 * Otherwise just update the call site. 649 */ 650 if (test_24bit_addr(ip, addr) && test_24bit_addr(ip, old_addr)) { 651 /* within range */ 652 old = ftrace_call_replace(ip, old_addr, 1); 653 new = ftrace_call_replace(ip, addr, 1); 654 return ftrace_modify_code(ip, old, new); 655 } else if (core_kernel_text(ip)) { 656 /* 657 * We always patch out of range locations to go to the regs 658 * variant, so there is nothing to do here 659 */ 660 return 0; 661 } else if (!IS_ENABLED(CONFIG_MODULES)) { 662 /* We should not get here without modules */ 663 return -EINVAL; 664 } 665 666 /* 667 * Out of range jumps are called from modules. 668 */ 669 if (!rec->arch.mod) { 670 pr_err("No module loaded\n"); 671 return -EINVAL; 672 } 673 674 return __ftrace_modify_call(rec, old_addr, addr); 675 } 676 #endif 677 678 int ftrace_update_ftrace_func(ftrace_func_t func) 679 { 680 unsigned long ip = (unsigned long)(&ftrace_call); 681 ppc_inst_t old, new; 682 int ret; 683 684 old = ppc_inst_read((u32 *)&ftrace_call); 685 new = ftrace_call_replace(ip, (unsigned long)func, 1); 686 ret = ftrace_modify_code(ip, old, new); 687 688 /* Also update the regs callback function */ 689 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) && !ret) { 690 ip = (unsigned long)(&ftrace_regs_call); 691 old = ppc_inst_read((u32 *)&ftrace_regs_call); 692 new = ftrace_call_replace(ip, (unsigned long)func, 1); 693 ret = ftrace_modify_code(ip, old, new); 694 } 695 696 return ret; 697 } 698 699 /* 700 * Use the default ftrace_modify_all_code, but without 701 * stop_machine(). 702 */ 703 void arch_ftrace_update_code(int command) 704 { 705 ftrace_modify_all_code(command); 706 } 707 708 #ifdef CONFIG_PPC64 709 #define PACATOC offsetof(struct paca_struct, kernel_toc) 710 711 extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[]; 712 713 void ftrace_free_init_tramp(void) 714 { 715 int i; 716 717 for (i = 0; i < NUM_FTRACE_TRAMPS && ftrace_tramps[i]; i++) 718 if (ftrace_tramps[i] == (unsigned long)ftrace_tramp_init) { 719 ftrace_tramps[i] = 0; 720 return; 721 } 722 } 723 724 int __init ftrace_dyn_arch_init(void) 725 { 726 int i; 727 unsigned int *tramp[] = { ftrace_tramp_text, ftrace_tramp_init }; 728 u32 stub_insns[] = { 729 PPC_RAW_LD(_R12, _R13, PACATOC), 730 PPC_RAW_ADDIS(_R12, _R12, 0), 731 PPC_RAW_ADDI(_R12, _R12, 0), 732 PPC_RAW_MTCTR(_R12), 733 PPC_RAW_BCTR() 734 }; 735 unsigned long addr; 736 long reladdr; 737 738 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) 739 addr = ppc_global_function_entry((void *)ftrace_regs_caller); 740 else 741 addr = ppc_global_function_entry((void *)ftrace_caller); 742 743 reladdr = addr - kernel_toc_addr(); 744 745 if (reladdr >= SZ_2G || reladdr < -(long)SZ_2G) { 746 pr_err("Address of %ps out of range of kernel_toc.\n", 747 (void *)addr); 748 return -1; 749 } 750 751 for (i = 0; i < 2; i++) { 752 memcpy(tramp[i], stub_insns, sizeof(stub_insns)); 753 tramp[i][1] |= PPC_HA(reladdr); 754 tramp[i][2] |= PPC_LO(reladdr); 755 add_ftrace_tramp((unsigned long)tramp[i]); 756 } 757 758 return 0; 759 } 760 #endif 761 762 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 763 764 extern void ftrace_graph_call(void); 765 extern void ftrace_graph_stub(void); 766 767 static int ftrace_modify_ftrace_graph_caller(bool enable) 768 { 769 unsigned long ip = (unsigned long)(&ftrace_graph_call); 770 unsigned long addr = (unsigned long)(&ftrace_graph_caller); 771 unsigned long stub = (unsigned long)(&ftrace_graph_stub); 772 ppc_inst_t old, new; 773 774 if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_ARGS)) 775 return 0; 776 777 old = ftrace_call_replace(ip, enable ? stub : addr, 0); 778 new = ftrace_call_replace(ip, enable ? addr : stub, 0); 779 780 return ftrace_modify_code(ip, old, new); 781 } 782 783 int ftrace_enable_ftrace_graph_caller(void) 784 { 785 return ftrace_modify_ftrace_graph_caller(true); 786 } 787 788 int ftrace_disable_ftrace_graph_caller(void) 789 { 790 return ftrace_modify_ftrace_graph_caller(false); 791 } 792 793 /* 794 * Hook the return address and push it in the stack of return addrs 795 * in current thread info. Return the address we want to divert to. 796 */ 797 static unsigned long 798 __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp) 799 { 800 unsigned long return_hooker; 801 int bit; 802 803 if (unlikely(ftrace_graph_is_dead())) 804 goto out; 805 806 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 807 goto out; 808 809 bit = ftrace_test_recursion_trylock(ip, parent); 810 if (bit < 0) 811 goto out; 812 813 return_hooker = ppc_function_entry(return_to_handler); 814 815 if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp)) 816 parent = return_hooker; 817 818 ftrace_test_recursion_unlock(bit); 819 out: 820 return parent; 821 } 822 823 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS 824 void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, 825 struct ftrace_ops *op, struct ftrace_regs *fregs) 826 { 827 fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]); 828 } 829 #else 830 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip, 831 unsigned long sp) 832 { 833 return __prepare_ftrace_return(parent, ip, sp); 834 } 835 #endif 836 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 837 838 #ifdef CONFIG_PPC64_ELF_ABI_V1 839 char *arch_ftrace_match_adjust(char *str, const char *search) 840 { 841 if (str[0] == '.' && search[0] != '.') 842 return str + 1; 843 else 844 return str; 845 } 846 #endif /* CONFIG_PPC64_ELF_ABI_V1 */ 847