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