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