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