| 1 | /* |
| 2 | * Code for replacing ftrace calls with jumps. |
| 3 | * |
| 4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> |
| 5 | * |
| 6 | * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box. |
| 7 | * |
| 8 | * Added function graph tracer code, taken from x86 that was written |
| 9 | * by Frederic Weisbecker, and ported to PPC by Steven Rostedt. |
| 10 | * |
| 11 | */ |
| 12 | |
| 13 | #include <linux/spinlock.h> |
| 14 | #include <linux/hardirq.h> |
| 15 | #include <linux/uaccess.h> |
| 16 | #include <linux/module.h> |
| 17 | #include <linux/ftrace.h> |
| 18 | #include <linux/percpu.h> |
| 19 | #include <linux/init.h> |
| 20 | #include <linux/list.h> |
| 21 | |
| 22 | #include <asm/cacheflush.h> |
| 23 | #include <asm/code-patching.h> |
| 24 | #include <asm/ftrace.h> |
| 25 | #include <asm/syscall.h> |
| 26 | |
| 27 | |
| 28 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 29 | static unsigned int |
| 30 | ftrace_call_replace(unsigned long ip, unsigned long addr, int link) |
| 31 | { |
| 32 | unsigned int op; |
| 33 | |
| 34 | addr = ppc_function_entry((void *)addr); |
| 35 | |
| 36 | /* if (link) set op to 'bl' else 'b' */ |
| 37 | op = create_branch((unsigned int *)ip, addr, link ? 1 : 0); |
| 38 | |
| 39 | return op; |
| 40 | } |
| 41 | |
| 42 | static int |
| 43 | ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) |
| 44 | { |
| 45 | unsigned int replaced; |
| 46 | |
| 47 | /* |
| 48 | * Note: Due to modules and __init, code can |
| 49 | * disappear and change, we need to protect against faulting |
| 50 | * as well as code changing. We do this by using the |
| 51 | * probe_kernel_* functions. |
| 52 | * |
| 53 | * No real locking needed, this code is run through |
| 54 | * kstop_machine, or before SMP starts. |
| 55 | */ |
| 56 | |
| 57 | /* read the text we want to modify */ |
| 58 | if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE)) |
| 59 | return -EFAULT; |
| 60 | |
| 61 | /* Make sure it is what we expect it to be */ |
| 62 | if (replaced != old) |
| 63 | return -EINVAL; |
| 64 | |
| 65 | /* replace the text with the new text */ |
| 66 | if (patch_instruction((unsigned int *)ip, new)) |
| 67 | return -EPERM; |
| 68 | |
| 69 | return 0; |
| 70 | } |
| 71 | |
| 72 | /* |
| 73 | * Helper functions that are the same for both PPC64 and PPC32. |
| 74 | */ |
| 75 | static int test_24bit_addr(unsigned long ip, unsigned long addr) |
| 76 | { |
| 77 | |
| 78 | /* use the create_branch to verify that this offset can be branched */ |
| 79 | return create_branch((unsigned int *)ip, addr, 0); |
| 80 | } |
| 81 | |
| 82 | #ifdef CONFIG_MODULES |
| 83 | |
| 84 | static int is_bl_op(unsigned int op) |
| 85 | { |
| 86 | return (op & 0xfc000003) == 0x48000001; |
| 87 | } |
| 88 | |
| 89 | static unsigned long find_bl_target(unsigned long ip, unsigned int op) |
| 90 | { |
| 91 | static int offset; |
| 92 | |
| 93 | offset = (op & 0x03fffffc); |
| 94 | /* make it signed */ |
| 95 | if (offset & 0x02000000) |
| 96 | offset |= 0xfe000000; |
| 97 | |
| 98 | return ip + (long)offset; |
| 99 | } |
| 100 | |
| 101 | #ifdef CONFIG_PPC64 |
| 102 | static int |
| 103 | __ftrace_make_nop(struct module *mod, |
| 104 | struct dyn_ftrace *rec, unsigned long addr) |
| 105 | { |
| 106 | unsigned int op; |
| 107 | unsigned int jmp[5]; |
| 108 | unsigned long ptr; |
| 109 | unsigned long ip = rec->ip; |
| 110 | unsigned long tramp; |
| 111 | int offset; |
| 112 | |
| 113 | /* read where this goes */ |
| 114 | if (probe_kernel_read(&op, (void *)ip, sizeof(int))) |
| 115 | return -EFAULT; |
| 116 | |
| 117 | /* Make sure that that this is still a 24bit jump */ |
| 118 | if (!is_bl_op(op)) { |
| 119 | printk(KERN_ERR "Not expected bl: opcode is %x\n", op); |
| 120 | return -EINVAL; |
| 121 | } |
| 122 | |
| 123 | /* lets find where the pointer goes */ |
| 124 | tramp = find_bl_target(ip, op); |
| 125 | |
| 126 | /* |
| 127 | * On PPC64 the trampoline looks like: |
| 128 | * 0x3d, 0x82, 0x00, 0x00, addis r12,r2, <high> |
| 129 | * 0x39, 0x8c, 0x00, 0x00, addi r12,r12, <low> |
| 130 | * Where the bytes 2,3,6 and 7 make up the 32bit offset |
| 131 | * to the TOC that holds the pointer. |
| 132 | * to jump to. |
| 133 | * 0xf8, 0x41, 0x00, 0x28, std r2,40(r1) |
| 134 | * 0xe9, 0x6c, 0x00, 0x20, ld r11,32(r12) |
| 135 | * The actually address is 32 bytes from the offset |
| 136 | * into the TOC. |
| 137 | * 0xe8, 0x4c, 0x00, 0x28, ld r2,40(r12) |
| 138 | */ |
| 139 | |
| 140 | pr_devel("ip:%lx jumps to %lx r2: %lx", ip, tramp, mod->arch.toc); |
| 141 | |
| 142 | /* Find where the trampoline jumps to */ |
| 143 | if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) { |
| 144 | printk(KERN_ERR "Failed to read %lx\n", tramp); |
| 145 | return -EFAULT; |
| 146 | } |
| 147 | |
| 148 | pr_devel(" %08x %08x", jmp[0], jmp[1]); |
| 149 | |
| 150 | /* verify that this is what we expect it to be */ |
| 151 | if (((jmp[0] & 0xffff0000) != 0x3d820000) || |
| 152 | ((jmp[1] & 0xffff0000) != 0x398c0000) || |
| 153 | (jmp[2] != 0xf8410028) || |
| 154 | (jmp[3] != 0xe96c0020) || |
| 155 | (jmp[4] != 0xe84c0028)) { |
| 156 | printk(KERN_ERR "Not a trampoline\n"); |
| 157 | return -EINVAL; |
| 158 | } |
| 159 | |
| 160 | /* The bottom half is signed extended */ |
| 161 | offset = ((unsigned)((unsigned short)jmp[0]) << 16) + |
| 162 | (int)((short)jmp[1]); |
| 163 | |
| 164 | pr_devel(" %x ", offset); |
| 165 | |
| 166 | /* get the address this jumps too */ |
| 167 | tramp = mod->arch.toc + offset + 32; |
| 168 | pr_devel("toc: %lx", tramp); |
| 169 | |
| 170 | if (probe_kernel_read(jmp, (void *)tramp, 8)) { |
| 171 | printk(KERN_ERR "Failed to read %lx\n", tramp); |
| 172 | return -EFAULT; |
| 173 | } |
| 174 | |
| 175 | pr_devel(" %08x %08x\n", jmp[0], jmp[1]); |
| 176 | |
| 177 | ptr = ((unsigned long)jmp[0] << 32) + jmp[1]; |
| 178 | |
| 179 | /* This should match what was called */ |
| 180 | if (ptr != ppc_function_entry((void *)addr)) { |
| 181 | printk(KERN_ERR "addr does not match %lx\n", ptr); |
| 182 | return -EINVAL; |
| 183 | } |
| 184 | |
| 185 | /* |
| 186 | * We want to nop the line, but the next line is |
| 187 | * 0xe8, 0x41, 0x00, 0x28 ld r2,40(r1) |
| 188 | * This needs to be turned to a nop too. |
| 189 | */ |
| 190 | if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) |
| 191 | return -EFAULT; |
| 192 | |
| 193 | if (op != 0xe8410028) { |
| 194 | printk(KERN_ERR "Next line is not ld! (%08x)\n", op); |
| 195 | return -EINVAL; |
| 196 | } |
| 197 | |
| 198 | /* |
| 199 | * Milton Miller pointed out that we can not blindly do nops. |
| 200 | * If a task was preempted when calling a trace function, |
| 201 | * the nops will remove the way to restore the TOC in r2 |
| 202 | * and the r2 TOC will get corrupted. |
| 203 | */ |
| 204 | |
| 205 | /* |
| 206 | * Replace: |
| 207 | * bl <tramp> <==== will be replaced with "b 1f" |
| 208 | * ld r2,40(r1) |
| 209 | * 1: |
| 210 | */ |
| 211 | op = 0x48000008; /* b +8 */ |
| 212 | |
| 213 | if (patch_instruction((unsigned int *)ip, op)) |
| 214 | return -EPERM; |
| 215 | |
| 216 | return 0; |
| 217 | } |
| 218 | |
| 219 | #else /* !PPC64 */ |
| 220 | static int |
| 221 | __ftrace_make_nop(struct module *mod, |
| 222 | struct dyn_ftrace *rec, unsigned long addr) |
| 223 | { |
| 224 | unsigned int op; |
| 225 | unsigned int jmp[4]; |
| 226 | unsigned long ip = rec->ip; |
| 227 | unsigned long tramp; |
| 228 | |
| 229 | if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE)) |
| 230 | return -EFAULT; |
| 231 | |
| 232 | /* Make sure that that this is still a 24bit jump */ |
| 233 | if (!is_bl_op(op)) { |
| 234 | printk(KERN_ERR "Not expected bl: opcode is %x\n", op); |
| 235 | return -EINVAL; |
| 236 | } |
| 237 | |
| 238 | /* lets find where the pointer goes */ |
| 239 | tramp = find_bl_target(ip, op); |
| 240 | |
| 241 | /* |
| 242 | * On PPC32 the trampoline looks like: |
| 243 | * 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha |
| 244 | * 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l |
| 245 | * 0x7d, 0x89, 0x03, 0xa6 mtctr r12 |
| 246 | * 0x4e, 0x80, 0x04, 0x20 bctr |
| 247 | */ |
| 248 | |
| 249 | pr_devel("ip:%lx jumps to %lx", ip, tramp); |
| 250 | |
| 251 | /* Find where the trampoline jumps to */ |
| 252 | if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) { |
| 253 | printk(KERN_ERR "Failed to read %lx\n", tramp); |
| 254 | return -EFAULT; |
| 255 | } |
| 256 | |
| 257 | pr_devel(" %08x %08x ", jmp[0], jmp[1]); |
| 258 | |
| 259 | /* verify that this is what we expect it to be */ |
| 260 | if (((jmp[0] & 0xffff0000) != 0x3d800000) || |
| 261 | ((jmp[1] & 0xffff0000) != 0x398c0000) || |
| 262 | (jmp[2] != 0x7d8903a6) || |
| 263 | (jmp[3] != 0x4e800420)) { |
| 264 | printk(KERN_ERR "Not a trampoline\n"); |
| 265 | return -EINVAL; |
| 266 | } |
| 267 | |
| 268 | tramp = (jmp[1] & 0xffff) | |
| 269 | ((jmp[0] & 0xffff) << 16); |
| 270 | if (tramp & 0x8000) |
| 271 | tramp -= 0x10000; |
| 272 | |
| 273 | pr_devel(" %lx ", tramp); |
| 274 | |
| 275 | if (tramp != addr) { |
| 276 | printk(KERN_ERR |
| 277 | "Trampoline location %08lx does not match addr\n", |
| 278 | tramp); |
| 279 | return -EINVAL; |
| 280 | } |
| 281 | |
| 282 | op = PPC_INST_NOP; |
| 283 | |
| 284 | if (patch_instruction((unsigned int *)ip, op)) |
| 285 | return -EPERM; |
| 286 | |
| 287 | return 0; |
| 288 | } |
| 289 | #endif /* PPC64 */ |
| 290 | #endif /* CONFIG_MODULES */ |
| 291 | |
| 292 | int ftrace_make_nop(struct module *mod, |
| 293 | struct dyn_ftrace *rec, unsigned long addr) |
| 294 | { |
| 295 | unsigned long ip = rec->ip; |
| 296 | unsigned int old, new; |
| 297 | |
| 298 | /* |
| 299 | * If the calling address is more that 24 bits away, |
| 300 | * then we had to use a trampoline to make the call. |
| 301 | * Otherwise just update the call site. |
| 302 | */ |
| 303 | if (test_24bit_addr(ip, addr)) { |
| 304 | /* within range */ |
| 305 | old = ftrace_call_replace(ip, addr, 1); |
| 306 | new = PPC_INST_NOP; |
| 307 | return ftrace_modify_code(ip, old, new); |
| 308 | } |
| 309 | |
| 310 | #ifdef CONFIG_MODULES |
| 311 | /* |
| 312 | * Out of range jumps are called from modules. |
| 313 | * We should either already have a pointer to the module |
| 314 | * or it has been passed in. |
| 315 | */ |
| 316 | if (!rec->arch.mod) { |
| 317 | if (!mod) { |
| 318 | printk(KERN_ERR "No module loaded addr=%lx\n", |
| 319 | addr); |
| 320 | return -EFAULT; |
| 321 | } |
| 322 | rec->arch.mod = mod; |
| 323 | } else if (mod) { |
| 324 | if (mod != rec->arch.mod) { |
| 325 | printk(KERN_ERR |
| 326 | "Record mod %p not equal to passed in mod %p\n", |
| 327 | rec->arch.mod, mod); |
| 328 | return -EINVAL; |
| 329 | } |
| 330 | /* nothing to do if mod == rec->arch.mod */ |
| 331 | } else |
| 332 | mod = rec->arch.mod; |
| 333 | |
| 334 | return __ftrace_make_nop(mod, rec, addr); |
| 335 | #else |
| 336 | /* We should not get here without modules */ |
| 337 | return -EINVAL; |
| 338 | #endif /* CONFIG_MODULES */ |
| 339 | } |
| 340 | |
| 341 | #ifdef CONFIG_MODULES |
| 342 | #ifdef CONFIG_PPC64 |
| 343 | static int |
| 344 | __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
| 345 | { |
| 346 | unsigned int op[2]; |
| 347 | unsigned long ip = rec->ip; |
| 348 | |
| 349 | /* read where this goes */ |
| 350 | if (probe_kernel_read(op, (void *)ip, MCOUNT_INSN_SIZE * 2)) |
| 351 | return -EFAULT; |
| 352 | |
| 353 | /* |
| 354 | * It should be pointing to two nops or |
| 355 | * b +8; ld r2,40(r1) |
| 356 | */ |
| 357 | if (((op[0] != 0x48000008) || (op[1] != 0xe8410028)) && |
| 358 | ((op[0] != PPC_INST_NOP) || (op[1] != PPC_INST_NOP))) { |
| 359 | printk(KERN_ERR "Expected NOPs but have %x %x\n", op[0], op[1]); |
| 360 | return -EINVAL; |
| 361 | } |
| 362 | |
| 363 | /* If we never set up a trampoline to ftrace_caller, then bail */ |
| 364 | if (!rec->arch.mod->arch.tramp) { |
| 365 | printk(KERN_ERR "No ftrace trampoline\n"); |
| 366 | return -EINVAL; |
| 367 | } |
| 368 | |
| 369 | /* create the branch to the trampoline */ |
| 370 | op[0] = create_branch((unsigned int *)ip, |
| 371 | rec->arch.mod->arch.tramp, BRANCH_SET_LINK); |
| 372 | if (!op[0]) { |
| 373 | printk(KERN_ERR "REL24 out of range!\n"); |
| 374 | return -EINVAL; |
| 375 | } |
| 376 | |
| 377 | /* ld r2,40(r1) */ |
| 378 | op[1] = 0xe8410028; |
| 379 | |
| 380 | pr_devel("write to %lx\n", rec->ip); |
| 381 | |
| 382 | if (probe_kernel_write((void *)ip, op, MCOUNT_INSN_SIZE * 2)) |
| 383 | return -EPERM; |
| 384 | |
| 385 | flush_icache_range(ip, ip + 8); |
| 386 | |
| 387 | return 0; |
| 388 | } |
| 389 | #else |
| 390 | static int |
| 391 | __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
| 392 | { |
| 393 | unsigned int op; |
| 394 | unsigned long ip = rec->ip; |
| 395 | |
| 396 | /* read where this goes */ |
| 397 | if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE)) |
| 398 | return -EFAULT; |
| 399 | |
| 400 | /* It should be pointing to a nop */ |
| 401 | if (op != PPC_INST_NOP) { |
| 402 | printk(KERN_ERR "Expected NOP but have %x\n", op); |
| 403 | return -EINVAL; |
| 404 | } |
| 405 | |
| 406 | /* If we never set up a trampoline to ftrace_caller, then bail */ |
| 407 | if (!rec->arch.mod->arch.tramp) { |
| 408 | printk(KERN_ERR "No ftrace trampoline\n"); |
| 409 | return -EINVAL; |
| 410 | } |
| 411 | |
| 412 | /* create the branch to the trampoline */ |
| 413 | op = create_branch((unsigned int *)ip, |
| 414 | rec->arch.mod->arch.tramp, BRANCH_SET_LINK); |
| 415 | if (!op) { |
| 416 | printk(KERN_ERR "REL24 out of range!\n"); |
| 417 | return -EINVAL; |
| 418 | } |
| 419 | |
| 420 | pr_devel("write to %lx\n", rec->ip); |
| 421 | |
| 422 | if (patch_instruction((unsigned int *)ip, op)) |
| 423 | return -EPERM; |
| 424 | |
| 425 | return 0; |
| 426 | } |
| 427 | #endif /* CONFIG_PPC64 */ |
| 428 | #endif /* CONFIG_MODULES */ |
| 429 | |
| 430 | int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) |
| 431 | { |
| 432 | unsigned long ip = rec->ip; |
| 433 | unsigned int old, new; |
| 434 | |
| 435 | /* |
| 436 | * If the calling address is more that 24 bits away, |
| 437 | * then we had to use a trampoline to make the call. |
| 438 | * Otherwise just update the call site. |
| 439 | */ |
| 440 | if (test_24bit_addr(ip, addr)) { |
| 441 | /* within range */ |
| 442 | old = PPC_INST_NOP; |
| 443 | new = ftrace_call_replace(ip, addr, 1); |
| 444 | return ftrace_modify_code(ip, old, new); |
| 445 | } |
| 446 | |
| 447 | #ifdef CONFIG_MODULES |
| 448 | /* |
| 449 | * Out of range jumps are called from modules. |
| 450 | * Being that we are converting from nop, it had better |
| 451 | * already have a module defined. |
| 452 | */ |
| 453 | if (!rec->arch.mod) { |
| 454 | printk(KERN_ERR "No module loaded\n"); |
| 455 | return -EINVAL; |
| 456 | } |
| 457 | |
| 458 | return __ftrace_make_call(rec, addr); |
| 459 | #else |
| 460 | /* We should not get here without modules */ |
| 461 | return -EINVAL; |
| 462 | #endif /* CONFIG_MODULES */ |
| 463 | } |
| 464 | |
| 465 | int ftrace_update_ftrace_func(ftrace_func_t func) |
| 466 | { |
| 467 | unsigned long ip = (unsigned long)(&ftrace_call); |
| 468 | unsigned int old, new; |
| 469 | int ret; |
| 470 | |
| 471 | old = *(unsigned int *)&ftrace_call; |
| 472 | new = ftrace_call_replace(ip, (unsigned long)func, 1); |
| 473 | ret = ftrace_modify_code(ip, old, new); |
| 474 | |
| 475 | return ret; |
| 476 | } |
| 477 | |
| 478 | static int __ftrace_replace_code(struct dyn_ftrace *rec, int enable) |
| 479 | { |
| 480 | unsigned long ftrace_addr = (unsigned long)FTRACE_ADDR; |
| 481 | int ret; |
| 482 | |
| 483 | ret = ftrace_update_record(rec, enable); |
| 484 | |
| 485 | switch (ret) { |
| 486 | case FTRACE_UPDATE_IGNORE: |
| 487 | return 0; |
| 488 | case FTRACE_UPDATE_MAKE_CALL: |
| 489 | return ftrace_make_call(rec, ftrace_addr); |
| 490 | case FTRACE_UPDATE_MAKE_NOP: |
| 491 | return ftrace_make_nop(NULL, rec, ftrace_addr); |
| 492 | } |
| 493 | |
| 494 | return 0; |
| 495 | } |
| 496 | |
| 497 | void ftrace_replace_code(int enable) |
| 498 | { |
| 499 | struct ftrace_rec_iter *iter; |
| 500 | struct dyn_ftrace *rec; |
| 501 | int ret; |
| 502 | |
| 503 | for (iter = ftrace_rec_iter_start(); iter; |
| 504 | iter = ftrace_rec_iter_next(iter)) { |
| 505 | rec = ftrace_rec_iter_record(iter); |
| 506 | ret = __ftrace_replace_code(rec, enable); |
| 507 | if (ret) { |
| 508 | ftrace_bug(ret, rec->ip); |
| 509 | return; |
| 510 | } |
| 511 | } |
| 512 | } |
| 513 | |
| 514 | void arch_ftrace_update_code(int command) |
| 515 | { |
| 516 | if (command & FTRACE_UPDATE_CALLS) |
| 517 | ftrace_replace_code(1); |
| 518 | else if (command & FTRACE_DISABLE_CALLS) |
| 519 | ftrace_replace_code(0); |
| 520 | |
| 521 | if (command & FTRACE_UPDATE_TRACE_FUNC) |
| 522 | ftrace_update_ftrace_func(ftrace_trace_function); |
| 523 | |
| 524 | if (command & FTRACE_START_FUNC_RET) |
| 525 | ftrace_enable_ftrace_graph_caller(); |
| 526 | else if (command & FTRACE_STOP_FUNC_RET) |
| 527 | ftrace_disable_ftrace_graph_caller(); |
| 528 | } |
| 529 | |
| 530 | int __init ftrace_dyn_arch_init(void) |
| 531 | { |
| 532 | return 0; |
| 533 | } |
| 534 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
| 535 | |
| 536 | #ifdef CONFIG_FUNCTION_GRAPH_TRACER |
| 537 | |
| 538 | #ifdef CONFIG_DYNAMIC_FTRACE |
| 539 | extern void ftrace_graph_call(void); |
| 540 | extern void ftrace_graph_stub(void); |
| 541 | |
| 542 | int ftrace_enable_ftrace_graph_caller(void) |
| 543 | { |
| 544 | unsigned long ip = (unsigned long)(&ftrace_graph_call); |
| 545 | unsigned long addr = (unsigned long)(&ftrace_graph_caller); |
| 546 | unsigned long stub = (unsigned long)(&ftrace_graph_stub); |
| 547 | unsigned int old, new; |
| 548 | |
| 549 | old = ftrace_call_replace(ip, stub, 0); |
| 550 | new = ftrace_call_replace(ip, addr, 0); |
| 551 | |
| 552 | return ftrace_modify_code(ip, old, new); |
| 553 | } |
| 554 | |
| 555 | int ftrace_disable_ftrace_graph_caller(void) |
| 556 | { |
| 557 | unsigned long ip = (unsigned long)(&ftrace_graph_call); |
| 558 | unsigned long addr = (unsigned long)(&ftrace_graph_caller); |
| 559 | unsigned long stub = (unsigned long)(&ftrace_graph_stub); |
| 560 | unsigned int old, new; |
| 561 | |
| 562 | old = ftrace_call_replace(ip, addr, 0); |
| 563 | new = ftrace_call_replace(ip, stub, 0); |
| 564 | |
| 565 | return ftrace_modify_code(ip, old, new); |
| 566 | } |
| 567 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
| 568 | |
| 569 | #ifdef CONFIG_PPC64 |
| 570 | extern void mod_return_to_handler(void); |
| 571 | #endif |
| 572 | |
| 573 | /* |
| 574 | * Hook the return address and push it in the stack of return addrs |
| 575 | * in current thread info. |
| 576 | */ |
| 577 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) |
| 578 | { |
| 579 | unsigned long old; |
| 580 | int faulted; |
| 581 | struct ftrace_graph_ent trace; |
| 582 | unsigned long return_hooker = (unsigned long)&return_to_handler; |
| 583 | |
| 584 | if (unlikely(atomic_read(¤t->tracing_graph_pause))) |
| 585 | return; |
| 586 | |
| 587 | #ifdef CONFIG_PPC64 |
| 588 | /* non core kernel code needs to save and restore the TOC */ |
| 589 | if (REGION_ID(self_addr) != KERNEL_REGION_ID) |
| 590 | return_hooker = (unsigned long)&mod_return_to_handler; |
| 591 | #endif |
| 592 | |
| 593 | return_hooker = ppc_function_entry((void *)return_hooker); |
| 594 | |
| 595 | /* |
| 596 | * Protect against fault, even if it shouldn't |
| 597 | * happen. This tool is too much intrusive to |
| 598 | * ignore such a protection. |
| 599 | */ |
| 600 | asm volatile( |
| 601 | "1: " PPC_LL "%[old], 0(%[parent])\n" |
| 602 | "2: " PPC_STL "%[return_hooker], 0(%[parent])\n" |
| 603 | " li %[faulted], 0\n" |
| 604 | "3:\n" |
| 605 | |
| 606 | ".section .fixup, \"ax\"\n" |
| 607 | "4: li %[faulted], 1\n" |
| 608 | " b 3b\n" |
| 609 | ".previous\n" |
| 610 | |
| 611 | ".section __ex_table,\"a\"\n" |
| 612 | PPC_LONG_ALIGN "\n" |
| 613 | PPC_LONG "1b,4b\n" |
| 614 | PPC_LONG "2b,4b\n" |
| 615 | ".previous" |
| 616 | |
| 617 | : [old] "=&r" (old), [faulted] "=r" (faulted) |
| 618 | : [parent] "r" (parent), [return_hooker] "r" (return_hooker) |
| 619 | : "memory" |
| 620 | ); |
| 621 | |
| 622 | if (unlikely(faulted)) { |
| 623 | ftrace_graph_stop(); |
| 624 | WARN_ON(1); |
| 625 | return; |
| 626 | } |
| 627 | |
| 628 | trace.func = self_addr; |
| 629 | trace.depth = current->curr_ret_stack + 1; |
| 630 | |
| 631 | /* Only trace if the calling function expects to */ |
| 632 | if (!ftrace_graph_entry(&trace)) { |
| 633 | *parent = old; |
| 634 | return; |
| 635 | } |
| 636 | |
| 637 | if (ftrace_push_return_trace(old, self_addr, &trace.depth, 0) == -EBUSY) |
| 638 | *parent = old; |
| 639 | } |
| 640 | #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |
| 641 | |
| 642 | #if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64) |
| 643 | unsigned long __init arch_syscall_addr(int nr) |
| 644 | { |
| 645 | return sys_call_table[nr*2]; |
| 646 | } |
| 647 | #endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_PPC64 */ |