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/init.h> 25 #include <linux/completion.h> 26 #include <linux/kallsyms.h> 27 #include <linux/random.h> 28 #include <linux/prctl.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/msa.h> 36 #include <asm/pgtable.h> 37 #include <asm/mipsregs.h> 38 #include <asm/processor.h> 39 #include <asm/reg.h> 40 #include <asm/uaccess.h> 41 #include <asm/io.h> 42 #include <asm/elf.h> 43 #include <asm/isadep.h> 44 #include <asm/inst.h> 45 #include <asm/stacktrace.h> 46 #include <asm/irq_regs.h> 47 48 #ifdef CONFIG_HOTPLUG_CPU 49 void arch_cpu_idle_dead(void) 50 { 51 /* What the heck is this check doing ? */ 52 if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map)) 53 play_dead(); 54 } 55 #endif 56 57 asmlinkage void ret_from_fork(void); 58 asmlinkage void ret_from_kernel_thread(void); 59 60 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 61 { 62 unsigned long status; 63 64 /* New thread loses kernel privileges. */ 65 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK); 66 status |= KU_USER; 67 regs->cp0_status = status; 68 clear_used_math(); 69 clear_fpu_owner(); 70 init_dsp(); 71 clear_thread_flag(TIF_USEDMSA); 72 clear_thread_flag(TIF_MSA_CTX_LIVE); 73 disable_msa(); 74 regs->cp0_epc = pc; 75 regs->regs[29] = sp; 76 } 77 78 void exit_thread(void) 79 { 80 } 81 82 void flush_thread(void) 83 { 84 } 85 86 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 87 { 88 /* 89 * Save any process state which is live in hardware registers to the 90 * parent context prior to duplication. This prevents the new child 91 * state becoming stale if the parent is preempted before copy_thread() 92 * gets a chance to save the parent's live hardware registers to the 93 * child context. 94 */ 95 preempt_disable(); 96 97 if (is_msa_enabled()) 98 save_msa(current); 99 else if (is_fpu_owner()) 100 _save_fp(current); 101 102 save_dsp(current); 103 104 preempt_enable(); 105 106 *dst = *src; 107 return 0; 108 } 109 110 /* 111 * Copy architecture-specific thread state 112 */ 113 int copy_thread(unsigned long clone_flags, unsigned long usp, 114 unsigned long kthread_arg, struct task_struct *p) 115 { 116 struct thread_info *ti = task_thread_info(p); 117 struct pt_regs *childregs, *regs = current_pt_regs(); 118 unsigned long childksp; 119 p->set_child_tid = p->clear_child_tid = NULL; 120 121 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 122 123 /* set up new TSS. */ 124 childregs = (struct pt_regs *) childksp - 1; 125 /* Put the stack after the struct pt_regs. */ 126 childksp = (unsigned long) childregs; 127 p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1); 128 if (unlikely(p->flags & PF_KTHREAD)) { 129 /* kernel thread */ 130 unsigned long status = p->thread.cp0_status; 131 memset(childregs, 0, sizeof(struct pt_regs)); 132 ti->addr_limit = KERNEL_DS; 133 p->thread.reg16 = usp; /* fn */ 134 p->thread.reg17 = kthread_arg; 135 p->thread.reg29 = childksp; 136 p->thread.reg31 = (unsigned long) ret_from_kernel_thread; 137 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX) 138 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) | 139 ((status & (ST0_KUC | ST0_IEC)) << 2); 140 #else 141 status |= ST0_EXL; 142 #endif 143 childregs->cp0_status = status; 144 return 0; 145 } 146 147 /* user thread */ 148 *childregs = *regs; 149 childregs->regs[7] = 0; /* Clear error flag */ 150 childregs->regs[2] = 0; /* Child gets zero as return value */ 151 if (usp) 152 childregs->regs[29] = usp; 153 ti->addr_limit = USER_DS; 154 155 p->thread.reg29 = (unsigned long) childregs; 156 p->thread.reg31 = (unsigned long) ret_from_fork; 157 158 /* 159 * New tasks lose permission to use the fpu. This accelerates context 160 * switching for most programs since they don't use the fpu. 161 */ 162 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 163 164 clear_tsk_thread_flag(p, TIF_USEDFPU); 165 clear_tsk_thread_flag(p, TIF_USEDMSA); 166 clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE); 167 168 #ifdef CONFIG_MIPS_MT_FPAFF 169 clear_tsk_thread_flag(p, TIF_FPUBOUND); 170 #endif /* CONFIG_MIPS_MT_FPAFF */ 171 172 if (clone_flags & CLONE_SETTLS) 173 ti->tp_value = regs->regs[7]; 174 175 return 0; 176 } 177 178 #ifdef CONFIG_CC_STACKPROTECTOR 179 #include <linux/stackprotector.h> 180 unsigned long __stack_chk_guard __read_mostly; 181 EXPORT_SYMBOL(__stack_chk_guard); 182 #endif 183 184 struct mips_frame_info { 185 void *func; 186 unsigned long func_size; 187 int frame_size; 188 int pc_offset; 189 }; 190 191 #define J_TARGET(pc,target) \ 192 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) 193 194 static inline int is_ra_save_ins(union mips_instruction *ip) 195 { 196 #ifdef CONFIG_CPU_MICROMIPS 197 union mips_instruction mmi; 198 199 /* 200 * swsp ra,offset 201 * swm16 reglist,offset(sp) 202 * swm32 reglist,offset(sp) 203 * sw32 ra,offset(sp) 204 * jradiussp - NOT SUPPORTED 205 * 206 * microMIPS is way more fun... 207 */ 208 if (mm_insn_16bit(ip->halfword[0])) { 209 mmi.word = (ip->halfword[0] << 16); 210 return (mmi.mm16_r5_format.opcode == mm_swsp16_op && 211 mmi.mm16_r5_format.rt == 31) || 212 (mmi.mm16_m_format.opcode == mm_pool16c_op && 213 mmi.mm16_m_format.func == mm_swm16_op); 214 } 215 else { 216 mmi.halfword[0] = ip->halfword[1]; 217 mmi.halfword[1] = ip->halfword[0]; 218 return (mmi.mm_m_format.opcode == mm_pool32b_op && 219 mmi.mm_m_format.rd > 9 && 220 mmi.mm_m_format.base == 29 && 221 mmi.mm_m_format.func == mm_swm32_func) || 222 (mmi.i_format.opcode == mm_sw32_op && 223 mmi.i_format.rs == 29 && 224 mmi.i_format.rt == 31); 225 } 226 #else 227 /* sw / sd $ra, offset($sp) */ 228 return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 229 ip->i_format.rs == 29 && 230 ip->i_format.rt == 31; 231 #endif 232 } 233 234 static inline int is_jump_ins(union mips_instruction *ip) 235 { 236 #ifdef CONFIG_CPU_MICROMIPS 237 /* 238 * jr16,jrc,jalr16,jalr16 239 * jal 240 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb 241 * jraddiusp - NOT SUPPORTED 242 * 243 * microMIPS is kind of more fun... 244 */ 245 union mips_instruction mmi; 246 247 mmi.word = (ip->halfword[0] << 16); 248 249 if ((mmi.mm16_r5_format.opcode == mm_pool16c_op && 250 (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) || 251 ip->j_format.opcode == mm_jal32_op) 252 return 1; 253 if (ip->r_format.opcode != mm_pool32a_op || 254 ip->r_format.func != mm_pool32axf_op) 255 return 0; 256 return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op; 257 #else 258 if (ip->j_format.opcode == j_op) 259 return 1; 260 if (ip->j_format.opcode == jal_op) 261 return 1; 262 if (ip->r_format.opcode != spec_op) 263 return 0; 264 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 265 #endif 266 } 267 268 static inline int is_sp_move_ins(union mips_instruction *ip) 269 { 270 #ifdef CONFIG_CPU_MICROMIPS 271 /* 272 * addiusp -imm 273 * addius5 sp,-imm 274 * addiu32 sp,sp,-imm 275 * jradiussp - NOT SUPPORTED 276 * 277 * microMIPS is not more fun... 278 */ 279 if (mm_insn_16bit(ip->halfword[0])) { 280 union mips_instruction mmi; 281 282 mmi.word = (ip->halfword[0] << 16); 283 return (mmi.mm16_r3_format.opcode == mm_pool16d_op && 284 mmi.mm16_r3_format.simmediate && mm_addiusp_func) || 285 (mmi.mm16_r5_format.opcode == mm_pool16d_op && 286 mmi.mm16_r5_format.rt == 29); 287 } 288 return ip->mm_i_format.opcode == mm_addiu32_op && 289 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29; 290 #else 291 /* addiu/daddiu sp,sp,-imm */ 292 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 293 return 0; 294 if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op) 295 return 1; 296 #endif 297 return 0; 298 } 299 300 static int get_frame_info(struct mips_frame_info *info) 301 { 302 #ifdef CONFIG_CPU_MICROMIPS 303 union mips_instruction *ip = (void *) (((char *) info->func) - 1); 304 #else 305 union mips_instruction *ip = info->func; 306 #endif 307 unsigned max_insns = info->func_size / sizeof(union mips_instruction); 308 unsigned i; 309 310 info->pc_offset = -1; 311 info->frame_size = 0; 312 313 if (!ip) 314 goto err; 315 316 if (max_insns == 0) 317 max_insns = 128U; /* unknown function size */ 318 max_insns = min(128U, max_insns); 319 320 for (i = 0; i < max_insns; i++, ip++) { 321 322 if (is_jump_ins(ip)) 323 break; 324 if (!info->frame_size) { 325 if (is_sp_move_ins(ip)) 326 { 327 #ifdef CONFIG_CPU_MICROMIPS 328 if (mm_insn_16bit(ip->halfword[0])) 329 { 330 unsigned short tmp; 331 332 if (ip->halfword[0] & mm_addiusp_func) 333 { 334 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2); 335 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0)); 336 } else { 337 tmp = (ip->halfword[0] >> 1); 338 info->frame_size = -(signed short)(tmp & 0xf); 339 } 340 ip = (void *) &ip->halfword[1]; 341 ip--; 342 } else 343 #endif 344 info->frame_size = - ip->i_format.simmediate; 345 } 346 continue; 347 } 348 if (info->pc_offset == -1 && is_ra_save_ins(ip)) { 349 info->pc_offset = 350 ip->i_format.simmediate / sizeof(long); 351 break; 352 } 353 } 354 if (info->frame_size && info->pc_offset >= 0) /* nested */ 355 return 0; 356 if (info->pc_offset < 0) /* leaf */ 357 return 1; 358 /* prologue seems boggus... */ 359 err: 360 return -1; 361 } 362 363 static struct mips_frame_info schedule_mfi __read_mostly; 364 365 #ifdef CONFIG_KALLSYMS 366 static unsigned long get___schedule_addr(void) 367 { 368 return kallsyms_lookup_name("__schedule"); 369 } 370 #else 371 static unsigned long get___schedule_addr(void) 372 { 373 union mips_instruction *ip = (void *)schedule; 374 int max_insns = 8; 375 int i; 376 377 for (i = 0; i < max_insns; i++, ip++) { 378 if (ip->j_format.opcode == j_op) 379 return J_TARGET(ip, ip->j_format.target); 380 } 381 return 0; 382 } 383 #endif 384 385 static int __init frame_info_init(void) 386 { 387 unsigned long size = 0; 388 #ifdef CONFIG_KALLSYMS 389 unsigned long ofs; 390 #endif 391 unsigned long addr; 392 393 addr = get___schedule_addr(); 394 if (!addr) 395 addr = (unsigned long)schedule; 396 397 #ifdef CONFIG_KALLSYMS 398 kallsyms_lookup_size_offset(addr, &size, &ofs); 399 #endif 400 schedule_mfi.func = (void *)addr; 401 schedule_mfi.func_size = size; 402 403 get_frame_info(&schedule_mfi); 404 405 /* 406 * Without schedule() frame info, result given by 407 * thread_saved_pc() and get_wchan() are not reliable. 408 */ 409 if (schedule_mfi.pc_offset < 0) 410 printk("Can't analyze schedule() prologue at %p\n", schedule); 411 412 return 0; 413 } 414 415 arch_initcall(frame_info_init); 416 417 /* 418 * Return saved PC of a blocked thread. 419 */ 420 unsigned long thread_saved_pc(struct task_struct *tsk) 421 { 422 struct thread_struct *t = &tsk->thread; 423 424 /* New born processes are a special case */ 425 if (t->reg31 == (unsigned long) ret_from_fork) 426 return t->reg31; 427 if (schedule_mfi.pc_offset < 0) 428 return 0; 429 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 430 } 431 432 433 #ifdef CONFIG_KALLSYMS 434 /* generic stack unwinding function */ 435 unsigned long notrace unwind_stack_by_address(unsigned long stack_page, 436 unsigned long *sp, 437 unsigned long pc, 438 unsigned long *ra) 439 { 440 struct mips_frame_info info; 441 unsigned long size, ofs; 442 int leaf; 443 extern void ret_from_irq(void); 444 extern void ret_from_exception(void); 445 446 if (!stack_page) 447 return 0; 448 449 /* 450 * If we reached the bottom of interrupt context, 451 * return saved pc in pt_regs. 452 */ 453 if (pc == (unsigned long)ret_from_irq || 454 pc == (unsigned long)ret_from_exception) { 455 struct pt_regs *regs; 456 if (*sp >= stack_page && 457 *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) { 458 regs = (struct pt_regs *)*sp; 459 pc = regs->cp0_epc; 460 if (__kernel_text_address(pc)) { 461 *sp = regs->regs[29]; 462 *ra = regs->regs[31]; 463 return pc; 464 } 465 } 466 return 0; 467 } 468 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 469 return 0; 470 /* 471 * Return ra if an exception occurred at the first instruction 472 */ 473 if (unlikely(ofs == 0)) { 474 pc = *ra; 475 *ra = 0; 476 return pc; 477 } 478 479 info.func = (void *)(pc - ofs); 480 info.func_size = ofs; /* analyze from start to ofs */ 481 leaf = get_frame_info(&info); 482 if (leaf < 0) 483 return 0; 484 485 if (*sp < stack_page || 486 *sp + info.frame_size > stack_page + THREAD_SIZE - 32) 487 return 0; 488 489 if (leaf) 490 /* 491 * For some extreme cases, get_frame_info() can 492 * consider wrongly a nested function as a leaf 493 * one. In that cases avoid to return always the 494 * same value. 495 */ 496 pc = pc != *ra ? *ra : 0; 497 else 498 pc = ((unsigned long *)(*sp))[info.pc_offset]; 499 500 *sp += info.frame_size; 501 *ra = 0; 502 return __kernel_text_address(pc) ? pc : 0; 503 } 504 EXPORT_SYMBOL(unwind_stack_by_address); 505 506 /* used by show_backtrace() */ 507 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 508 unsigned long pc, unsigned long *ra) 509 { 510 unsigned long stack_page = (unsigned long)task_stack_page(task); 511 return unwind_stack_by_address(stack_page, sp, pc, ra); 512 } 513 #endif 514 515 /* 516 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 517 */ 518 unsigned long get_wchan(struct task_struct *task) 519 { 520 unsigned long pc = 0; 521 #ifdef CONFIG_KALLSYMS 522 unsigned long sp; 523 unsigned long ra = 0; 524 #endif 525 526 if (!task || task == current || task->state == TASK_RUNNING) 527 goto out; 528 if (!task_stack_page(task)) 529 goto out; 530 531 pc = thread_saved_pc(task); 532 533 #ifdef CONFIG_KALLSYMS 534 sp = task->thread.reg29 + schedule_mfi.frame_size; 535 536 while (in_sched_functions(pc)) 537 pc = unwind_stack(task, &sp, pc, &ra); 538 #endif 539 540 out: 541 return pc; 542 } 543 544 /* 545 * Don't forget that the stack pointer must be aligned on a 8 bytes 546 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 547 */ 548 unsigned long arch_align_stack(unsigned long sp) 549 { 550 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 551 sp -= get_random_int() & ~PAGE_MASK; 552 553 return sp & ALMASK; 554 } 555 556 static void arch_dump_stack(void *info) 557 { 558 struct pt_regs *regs; 559 560 regs = get_irq_regs(); 561 562 if (regs) 563 show_regs(regs); 564 565 dump_stack(); 566 } 567 568 void arch_trigger_all_cpu_backtrace(bool include_self) 569 { 570 smp_call_function(arch_dump_stack, NULL, 1); 571 } 572 573 int mips_get_process_fp_mode(struct task_struct *task) 574 { 575 int value = 0; 576 577 if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS)) 578 value |= PR_FP_MODE_FR; 579 if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS)) 580 value |= PR_FP_MODE_FRE; 581 582 return value; 583 } 584 585 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value) 586 { 587 const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE; 588 unsigned long switch_count; 589 struct task_struct *t; 590 591 /* Check the value is valid */ 592 if (value & ~known_bits) 593 return -EOPNOTSUPP; 594 595 /* Avoid inadvertently triggering emulation */ 596 if ((value & PR_FP_MODE_FR) && cpu_has_fpu && 597 !(current_cpu_data.fpu_id & MIPS_FPIR_F64)) 598 return -EOPNOTSUPP; 599 if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre) 600 return -EOPNOTSUPP; 601 602 /* FR = 0 not supported in MIPS R6 */ 603 if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6) 604 return -EOPNOTSUPP; 605 606 /* Save FP & vector context, then disable FPU & MSA */ 607 if (task->signal == current->signal) 608 lose_fpu(1); 609 610 /* Prevent any threads from obtaining live FP context */ 611 atomic_set(&task->mm->context.fp_mode_switching, 1); 612 smp_mb__after_atomic(); 613 614 /* 615 * If there are multiple online CPUs then wait until all threads whose 616 * FP mode is about to change have been context switched. This approach 617 * allows us to only worry about whether an FP mode switch is in 618 * progress when FP is first used in a tasks time slice. Pretty much all 619 * of the mode switch overhead can thus be confined to cases where mode 620 * switches are actually occuring. That is, to here. However for the 621 * thread performing the mode switch it may take a while... 622 */ 623 if (num_online_cpus() > 1) { 624 spin_lock_irq(&task->sighand->siglock); 625 626 for_each_thread(task, t) { 627 if (t == current) 628 continue; 629 630 switch_count = t->nvcsw + t->nivcsw; 631 632 do { 633 spin_unlock_irq(&task->sighand->siglock); 634 cond_resched(); 635 spin_lock_irq(&task->sighand->siglock); 636 } while ((t->nvcsw + t->nivcsw) == switch_count); 637 } 638 639 spin_unlock_irq(&task->sighand->siglock); 640 } 641 642 /* 643 * There are now no threads of the process with live FP context, so it 644 * is safe to proceed with the FP mode switch. 645 */ 646 for_each_thread(task, t) { 647 /* Update desired FP register width */ 648 if (value & PR_FP_MODE_FR) { 649 clear_tsk_thread_flag(t, TIF_32BIT_FPREGS); 650 } else { 651 set_tsk_thread_flag(t, TIF_32BIT_FPREGS); 652 clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE); 653 } 654 655 /* Update desired FP single layout */ 656 if (value & PR_FP_MODE_FRE) 657 set_tsk_thread_flag(t, TIF_HYBRID_FPREGS); 658 else 659 clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS); 660 } 661 662 /* Allow threads to use FP again */ 663 atomic_set(&task->mm->context.fp_mode_switching, 0); 664 665 return 0; 666 } 667