1 /* 2 * This file is subject to the terms and conditions of the GNU General Public 3 * License. See the file "COPYING" in the main directory of this archive 4 * for more details. 5 * 6 * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others. 7 * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org) 8 * Copyright (C) 1999, 2000 Silicon Graphics, Inc. 9 * Copyright (C) 2004 Thiemo Seufer 10 * Copyright (C) 2013 Imagination Technologies Ltd. 11 */ 12 #include <linux/errno.h> 13 #include <linux/sched.h> 14 #include <linux/tick.h> 15 #include <linux/kernel.h> 16 #include <linux/mm.h> 17 #include <linux/stddef.h> 18 #include <linux/unistd.h> 19 #include <linux/export.h> 20 #include <linux/ptrace.h> 21 #include <linux/mman.h> 22 #include <linux/personality.h> 23 #include <linux/sys.h> 24 #include <linux/user.h> 25 #include <linux/init.h> 26 #include <linux/completion.h> 27 #include <linux/kallsyms.h> 28 #include <linux/random.h> 29 30 #include <asm/asm.h> 31 #include <asm/bootinfo.h> 32 #include <asm/cpu.h> 33 #include <asm/dsp.h> 34 #include <asm/fpu.h> 35 #include <asm/pgtable.h> 36 #include <asm/mipsregs.h> 37 #include <asm/processor.h> 38 #include <asm/uaccess.h> 39 #include <asm/io.h> 40 #include <asm/elf.h> 41 #include <asm/isadep.h> 42 #include <asm/inst.h> 43 #include <asm/stacktrace.h> 44 45 #ifdef CONFIG_HOTPLUG_CPU 46 void arch_cpu_idle_dead(void) 47 { 48 /* What the heck is this check doing ? */ 49 if (!cpu_isset(smp_processor_id(), cpu_callin_map)) 50 play_dead(); 51 } 52 #endif 53 54 asmlinkage void ret_from_fork(void); 55 asmlinkage void ret_from_kernel_thread(void); 56 57 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 58 { 59 unsigned long status; 60 61 /* New thread loses kernel privileges. */ 62 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); 63 #ifdef CONFIG_64BIT 64 status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR; 65 #endif 66 status |= KU_USER; 67 regs->cp0_status = status; 68 clear_used_math(); 69 clear_fpu_owner(); 70 if (cpu_has_dsp) 71 __init_dsp(); 72 regs->cp0_epc = pc; 73 regs->regs[29] = sp; 74 } 75 76 void exit_thread(void) 77 { 78 } 79 80 void flush_thread(void) 81 { 82 } 83 84 int copy_thread(unsigned long clone_flags, unsigned long usp, 85 unsigned long arg, struct task_struct *p) 86 { 87 struct thread_info *ti = task_thread_info(p); 88 struct pt_regs *childregs, *regs = current_pt_regs(); 89 unsigned long childksp; 90 p->set_child_tid = p->clear_child_tid = NULL; 91 92 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 93 94 preempt_disable(); 95 96 if (is_fpu_owner()) 97 save_fp(p); 98 99 if (cpu_has_dsp) 100 save_dsp(p); 101 102 preempt_enable(); 103 104 /* set up new TSS. */ 105 childregs = (struct pt_regs *) childksp - 1; 106 /* Put the stack after the struct pt_regs. */ 107 childksp = (unsigned long) childregs; 108 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 109 if (unlikely(p->flags & PF_KTHREAD)) { 110 unsigned long status = p->thread.cp0_status; 111 memset(childregs, 0, sizeof(struct pt_regs)); 112 ti->addr_limit = KERNEL_DS; 113 p->thread.reg16 = usp; /* fn */ 114 p->thread.reg17 = arg; 115 p->thread.reg29 = childksp; 116 p->thread.reg31 = (unsigned long) ret_from_kernel_thread; 117 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 118 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 119 ((status & (ST0_KUC | ST0_IEC)) << 2); 120 #else 121 status |= ST0_EXL; 122 #endif 123 childregs->cp0_status = status; 124 return 0; 125 } 126 *childregs = *regs; 127 childregs->regs[7] = 0; /* Clear error flag */ 128 childregs->regs[2] = 0; /* Child gets zero as return value */ 129 if (usp) 130 childregs->regs[29] = usp; 131 ti->addr_limit = USER_DS; 132 133 p->thread.reg29 = (unsigned long) childregs; 134 p->thread.reg31 = (unsigned long) ret_from_fork; 135 136 /* 137 * New tasks lose permission to use the fpu. This accelerates context 138 * switching for most programs since they don't use the fpu. 139 */ 140 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 141 142 #ifdef CONFIG_MIPS_MT_SMTC 143 /* 144 * SMTC restores TCStatus after Status, and the CU bits 145 * are aliased there. 146 */ 147 childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1); 148 #endif 149 clear_tsk_thread_flag(p, TIF_USEDFPU); 150 151 #ifdef CONFIG_MIPS_MT_FPAFF 152 clear_tsk_thread_flag(p, TIF_FPUBOUND); 153 #endif /* CONFIG_MIPS_MT_FPAFF */ 154 155 if (clone_flags & CLONE_SETTLS) 156 ti->tp_value = regs->regs[7]; 157 158 return 0; 159 } 160 161 /* Fill in the fpu structure for a core dump.. */ 162 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r) 163 { 164 memcpy(r, ¤t->thread.fpu, sizeof(current->thread.fpu)); 165 166 return 1; 167 } 168 169 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs) 170 { 171 int i; 172 173 for (i = 0; i < EF_R0; i++) 174 gp[i] = 0; 175 gp[EF_R0] = 0; 176 for (i = 1; i <= 31; i++) 177 gp[EF_R0 + i] = regs->regs[i]; 178 gp[EF_R26] = 0; 179 gp[EF_R27] = 0; 180 gp[EF_LO] = regs->lo; 181 gp[EF_HI] = regs->hi; 182 gp[EF_CP0_EPC] = regs->cp0_epc; 183 gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr; 184 gp[EF_CP0_STATUS] = regs->cp0_status; 185 gp[EF_CP0_CAUSE] = regs->cp0_cause; 186 #ifdef EF_UNUSED0 187 gp[EF_UNUSED0] = 0; 188 #endif 189 } 190 191 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs) 192 { 193 elf_dump_regs(*regs, task_pt_regs(tsk)); 194 return 1; 195 } 196 197 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr) 198 { 199 memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu)); 200 201 return 1; 202 } 203 204 #ifdef CONFIG_CC_STACKPROTECTOR 205 #include <linux/stackprotector.h> 206 unsigned long __stack_chk_guard __read_mostly; 207 EXPORT_SYMBOL(__stack_chk_guard); 208 #endif 209 210 struct mips_frame_info { 211 void *func; 212 unsigned long func_size; 213 int frame_size; 214 int pc_offset; 215 }; 216 217 #define J_TARGET(pc,target) \ 218 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) 219 220 static inline int is_ra_save_ins(union mips_instruction *ip) 221 { 222 #ifdef CONFIG_CPU_MICROMIPS 223 union mips_instruction mmi; 224 225 /* 226 * swsp ra,offset 227 * swm16 reglist,offset(sp) 228 * swm32 reglist,offset(sp) 229 * sw32 ra,offset(sp) 230 * jradiussp - NOT SUPPORTED 231 * 232 * microMIPS is way more fun... 233 */ 234 if (mm_insn_16bit(ip->halfword[0])) { 235 mmi.word = (ip->halfword[0] << 16); 236 return ((mmi.mm16_r5_format.opcode == mm_swsp16_op && 237 mmi.mm16_r5_format.rt == 31) || 238 (mmi.mm16_m_format.opcode == mm_pool16c_op && 239 mmi.mm16_m_format.func == mm_swm16_op)); 240 } 241 else { 242 mmi.halfword[0] = ip->halfword[1]; 243 mmi.halfword[1] = ip->halfword[0]; 244 return ((mmi.mm_m_format.opcode == mm_pool32b_op && 245 mmi.mm_m_format.rd > 9 && 246 mmi.mm_m_format.base == 29 && 247 mmi.mm_m_format.func == mm_swm32_func) || 248 (mmi.i_format.opcode == mm_sw32_op && 249 mmi.i_format.rs == 29 && 250 mmi.i_format.rt == 31)); 251 } 252 #else 253 /* sw / sd $ra, offset($sp) */ 254 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 255 ip->i_format.rs == 29 && 256 ip->i_format.rt == 31; 257 #endif 258 } 259 260 static inline int is_jump_ins(union mips_instruction *ip) 261 { 262 #ifdef CONFIG_CPU_MICROMIPS 263 /* 264 * jr16,jrc,jalr16,jalr16 265 * jal 266 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb 267 * jraddiusp - NOT SUPPORTED 268 * 269 * microMIPS is kind of more fun... 270 */ 271 union mips_instruction mmi; 272 273 mmi.word = (ip->halfword[0] << 16); 274 275 if ((mmi.mm16_r5_format.opcode == mm_pool16c_op && 276 (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) || 277 ip->j_format.opcode == mm_jal32_op) 278 return 1; 279 if (ip->r_format.opcode != mm_pool32a_op || 280 ip->r_format.func != mm_pool32axf_op) 281 return 0; 282 return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op); 283 #else 284 if (ip->j_format.opcode == j_op) 285 return 1; 286 if (ip->j_format.opcode == jal_op) 287 return 1; 288 if (ip->r_format.opcode != spec_op) 289 return 0; 290 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 291 #endif 292 } 293 294 static inline int is_sp_move_ins(union mips_instruction *ip) 295 { 296 #ifdef CONFIG_CPU_MICROMIPS 297 /* 298 * addiusp -imm 299 * addius5 sp,-imm 300 * addiu32 sp,sp,-imm 301 * jradiussp - NOT SUPPORTED 302 * 303 * microMIPS is not more fun... 304 */ 305 if (mm_insn_16bit(ip->halfword[0])) { 306 union mips_instruction mmi; 307 308 mmi.word = (ip->halfword[0] << 16); 309 return ((mmi.mm16_r3_format.opcode == mm_pool16d_op && 310 mmi.mm16_r3_format.simmediate && mm_addiusp_func) || 311 (mmi.mm16_r5_format.opcode == mm_pool16d_op && 312 mmi.mm16_r5_format.rt == 29)); 313 } 314 return (ip->mm_i_format.opcode == mm_addiu32_op && 315 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29); 316 #else 317 /* addiu/daddiu sp,sp,-imm */ 318 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 319 return 0; 320 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 321 return 1; 322 #endif 323 return 0; 324 } 325 326 static int get_frame_info(struct mips_frame_info *info) 327 { 328 #ifdef CONFIG_CPU_MICROMIPS 329 union mips_instruction *ip = (void *) (((char *) info->func) - 1); 330 #else 331 union mips_instruction *ip = info->func; 332 #endif 333 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 334 unsigned i; 335 336 info->pc_offset = -1; 337 info->frame_size = 0; 338 339 if (!ip) 340 goto err; 341 342 if (max_insns == 0) 343 max_insns = 128U; /* unknown function size */ 344 max_insns = min(128U, max_insns); 345 346 for (i = 0; i < max_insns; i++, ip++) { 347 348 if (is_jump_ins(ip)) 349 break; 350 if (!info->frame_size) { 351 if (is_sp_move_ins(ip)) 352 { 353 #ifdef CONFIG_CPU_MICROMIPS 354 if (mm_insn_16bit(ip->halfword[0])) 355 { 356 unsigned short tmp; 357 358 if (ip->halfword[0] & mm_addiusp_func) 359 { 360 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2); 361 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0)); 362 } else { 363 tmp = (ip->halfword[0] >> 1); 364 info->frame_size = -(signed short)(tmp & 0xf); 365 } 366 ip = (void *) &ip->halfword[1]; 367 ip--; 368 } else 369 #endif 370 info->frame_size = - ip->i_format.simmediate; 371 } 372 continue; 373 } 374 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 375 info->pc_offset = 376 ip->i_format.simmediate / sizeof(long); 377 break; 378 } 379 } 380 if (info->frame_size && info->pc_offset >= 0) /* nested */ 381 return 0; 382 if (info->pc_offset < 0) /* leaf */ 383 return 1; 384 /* prologue seems boggus... */ 385 err: 386 return -1; 387 } 388 389 static struct mips_frame_info schedule_mfi __read_mostly; 390 391 #ifdef CONFIG_KALLSYMS 392 static unsigned long get___schedule_addr(void) 393 { 394 return kallsyms_lookup_name("__schedule"); 395 } 396 #else 397 static unsigned long get___schedule_addr(void) 398 { 399 union mips_instruction *ip = (void *)schedule; 400 int max_insns = 8; 401 int i; 402 403 for (i = 0; i < max_insns; i++, ip++) { 404 if (ip->j_format.opcode == j_op) 405 return J_TARGET(ip, ip->j_format.target); 406 } 407 return 0; 408 } 409 #endif 410 411 static int __init frame_info_init(void) 412 { 413 unsigned long size = 0; 414 #ifdef CONFIG_KALLSYMS 415 unsigned long ofs; 416 #endif 417 unsigned long addr; 418 419 addr = get___schedule_addr(); 420 if (!addr) 421 addr = (unsigned long)schedule; 422 423 #ifdef CONFIG_KALLSYMS 424 kallsyms_lookup_size_offset(addr, &size, &ofs); 425 #endif 426 schedule_mfi.func = (void *)addr; 427 schedule_mfi.func_size = size; 428 429 get_frame_info(&schedule_mfi); 430 431 /* 432 * Without schedule() frame info, result given by 433 * thread_saved_pc() and get_wchan() are not reliable. 434 */ 435 if (schedule_mfi.pc_offset < 0) 436 printk("Can't analyze schedule() prologue at %p\n", schedule); 437 438 return 0; 439 } 440 441 arch_initcall(frame_info_init); 442 443 /* 444 * Return saved PC of a blocked thread. 445 */ 446 unsigned long thread_saved_pc(struct task_struct *tsk) 447 { 448 struct thread_struct *t = &tsk->thread; 449 450 /* New born processes are a special case */ 451 if (t->reg31 == (unsigned long) ret_from_fork) 452 return t->reg31; 453 if (schedule_mfi.pc_offset < 0) 454 return 0; 455 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 456 } 457 458 459 #ifdef CONFIG_KALLSYMS 460 /* generic stack unwinding function */ 461 unsigned long notrace unwind_stack_by_address(unsigned long stack_page, 462 unsigned long *sp, 463 unsigned long pc, 464 unsigned long *ra) 465 { 466 struct mips_frame_info info; 467 unsigned long size, ofs; 468 int leaf; 469 extern void ret_from_irq(void); 470 extern void ret_from_exception(void); 471 472 if (!stack_page) 473 return 0; 474 475 /* 476 * If we reached the bottom of interrupt context, 477 * return saved pc in pt_regs. 478 */ 479 if (pc == (unsigned long)ret_from_irq || 480 pc == (unsigned long)ret_from_exception) { 481 struct pt_regs *regs; 482 if (*sp >= stack_page && 483 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 484 regs = (struct pt_regs *)*sp; 485 pc = regs->cp0_epc; 486 if (__kernel_text_address(pc)) { 487 *sp = regs->regs[29]; 488 *ra = regs->regs[31]; 489 return pc; 490 } 491 } 492 return 0; 493 } 494 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 495 return 0; 496 /* 497 * Return ra if an exception occurred at the first instruction 498 */ 499 if (unlikely(ofs == 0)) { 500 pc = *ra; 501 *ra = 0; 502 return pc; 503 } 504 505 info.func = (void *)(pc - ofs); 506 info.func_size = ofs; /* analyze from start to ofs */ 507 leaf = get_frame_info(&info); 508 if (leaf < 0) 509 return 0; 510 511 if (*sp < stack_page || 512 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 513 return 0; 514 515 if (leaf) 516 /* 517 * For some extreme cases, get_frame_info() can 518 * consider wrongly a nested function as a leaf 519 * one. In that cases avoid to return always the 520 * same value. 521 */ 522 pc = pc != *ra ? *ra : 0; 523 else 524 pc = ((unsigned long *)(*sp))[info.pc_offset]; 525 526 *sp += info.frame_size; 527 *ra = 0; 528 return __kernel_text_address(pc) ? pc : 0; 529 } 530 EXPORT_SYMBOL(unwind_stack_by_address); 531 532 /* used by show_backtrace() */ 533 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 534 unsigned long pc, unsigned long *ra) 535 { 536 unsigned long stack_page = (unsigned long)task_stack_page(task); 537 return unwind_stack_by_address(stack_page, sp, pc, ra); 538 } 539 #endif 540 541 /* 542 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 543 */ 544 unsigned long get_wchan(struct task_struct *task) 545 { 546 unsigned long pc = 0; 547 #ifdef CONFIG_KALLSYMS 548 unsigned long sp; 549 unsigned long ra = 0; 550 #endif 551 552 if (!task || task == current || task->state == TASK_RUNNING) 553 goto out; 554 if (!task_stack_page(task)) 555 goto out; 556 557 pc = thread_saved_pc(task); 558 559 #ifdef CONFIG_KALLSYMS 560 sp = task->thread.reg29 + schedule_mfi.frame_size; 561 562 while (in_sched_functions(pc)) 563 pc = unwind_stack(task, &sp, pc, &ra); 564 #endif 565 566 out: 567 return pc; 568 } 569 570 /* 571 * Don't forget that the stack pointer must be aligned on a 8 bytes 572 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 573 */ 574 unsigned long arch_align_stack(unsigned long sp) 575 { 576 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 577 sp -= get_random_int() & ~PAGE_MASK; 578 579 return sp & ALMASK; 580 } 581