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/cpu.h> 13 #include <linux/errno.h> 14 #include <linux/init.h> 15 #include <linux/kallsyms.h> 16 #include <linux/kernel.h> 17 #include <linux/nmi.h> 18 #include <linux/personality.h> 19 #include <linux/prctl.h> 20 #include <linux/random.h> 21 #include <linux/sched.h> 22 #include <linux/sched/debug.h> 23 #include <linux/sched/task_stack.h> 24 25 #include <asm/abi.h> 26 #include <asm/asm.h> 27 #include <asm/dsemul.h> 28 #include <asm/dsp.h> 29 #include <asm/exec.h> 30 #include <asm/fpu.h> 31 #include <asm/inst.h> 32 #include <asm/irq.h> 33 #include <asm/irq_regs.h> 34 #include <asm/isadep.h> 35 #include <asm/msa.h> 36 #include <asm/mips-cps.h> 37 #include <asm/mipsregs.h> 38 #include <asm/processor.h> 39 #include <asm/reg.h> 40 #include <asm/stacktrace.h> 41 42 #ifdef CONFIG_HOTPLUG_CPU 43 void arch_cpu_idle_dead(void) 44 { 45 play_dead(); 46 } 47 #endif 48 49 asmlinkage void ret_from_fork(void); 50 asmlinkage void ret_from_kernel_thread(void); 51 52 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) 53 { 54 unsigned long status; 55 56 /* New thread loses kernel privileges. */ 57 status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_CU2|ST0_FR|KU_MASK); 58 status |= KU_USER; 59 regs->cp0_status = status; 60 lose_fpu(0); 61 clear_thread_flag(TIF_MSA_CTX_LIVE); 62 clear_used_math(); 63 #ifdef CONFIG_MIPS_FP_SUPPORT 64 atomic_set(¤t->thread.bd_emu_frame, BD_EMUFRAME_NONE); 65 #endif 66 init_dsp(); 67 regs->cp0_epc = pc; 68 regs->regs[29] = sp; 69 } 70 71 void exit_thread(struct task_struct *tsk) 72 { 73 /* 74 * User threads may have allocated a delay slot emulation frame. 75 * If so, clean up that allocation. 76 */ 77 if (!(current->flags & PF_KTHREAD)) 78 dsemul_thread_cleanup(tsk); 79 } 80 81 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 82 { 83 /* 84 * Save any process state which is live in hardware registers to the 85 * parent context prior to duplication. This prevents the new child 86 * state becoming stale if the parent is preempted before copy_thread() 87 * gets a chance to save the parent's live hardware registers to the 88 * child context. 89 */ 90 preempt_disable(); 91 92 if (is_msa_enabled()) 93 save_msa(current); 94 else if (is_fpu_owner()) 95 _save_fp(current); 96 97 save_dsp(current); 98 99 preempt_enable(); 100 101 *dst = *src; 102 return 0; 103 } 104 105 /* 106 * Copy architecture-specific thread state 107 */ 108 int copy_thread(unsigned long clone_flags, unsigned long usp, 109 unsigned long kthread_arg, struct task_struct *p, 110 unsigned long tls) 111 { 112 struct thread_info *ti = task_thread_info(p); 113 struct pt_regs *childregs, *regs = current_pt_regs(); 114 unsigned long childksp; 115 116 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32; 117 118 /* set up new TSS. */ 119 childregs = (struct pt_regs *) childksp - 1; 120 /* Put the stack after the struct pt_regs. */ 121 childksp = (unsigned long) childregs; 122 p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK; 123 if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) { 124 /* kernel thread */ 125 unsigned long status = p->thread.cp0_status; 126 memset(childregs, 0, sizeof(struct pt_regs)); 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; 147 148 p->thread.reg29 = (unsigned long) childregs; 149 p->thread.reg31 = (unsigned long) ret_from_fork; 150 151 /* 152 * New tasks lose permission to use the fpu. This accelerates context 153 * switching for most programs since they don't use the fpu. 154 */ 155 childregs->cp0_status &= ~(ST0_CU2|ST0_CU1); 156 157 clear_tsk_thread_flag(p, TIF_USEDFPU); 158 clear_tsk_thread_flag(p, TIF_USEDMSA); 159 clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE); 160 161 #ifdef CONFIG_MIPS_MT_FPAFF 162 clear_tsk_thread_flag(p, TIF_FPUBOUND); 163 #endif /* CONFIG_MIPS_MT_FPAFF */ 164 165 #ifdef CONFIG_MIPS_FP_SUPPORT 166 atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE); 167 #endif 168 169 if (clone_flags & CLONE_SETTLS) 170 ti->tp_value = tls; 171 172 return 0; 173 } 174 175 #ifdef CONFIG_STACKPROTECTOR 176 #include <linux/stackprotector.h> 177 unsigned long __stack_chk_guard __read_mostly; 178 EXPORT_SYMBOL(__stack_chk_guard); 179 #endif 180 181 struct mips_frame_info { 182 void *func; 183 unsigned long func_size; 184 int frame_size; 185 int pc_offset; 186 }; 187 188 #define J_TARGET(pc,target) \ 189 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2)) 190 191 static inline int is_jr_ra_ins(union mips_instruction *ip) 192 { 193 #ifdef CONFIG_CPU_MICROMIPS 194 /* 195 * jr16 ra 196 * jr ra 197 */ 198 if (mm_insn_16bit(ip->word >> 16)) { 199 if (ip->mm16_r5_format.opcode == mm_pool16c_op && 200 ip->mm16_r5_format.rt == mm_jr16_op && 201 ip->mm16_r5_format.imm == 31) 202 return 1; 203 return 0; 204 } 205 206 if (ip->r_format.opcode == mm_pool32a_op && 207 ip->r_format.func == mm_pool32axf_op && 208 ((ip->u_format.uimmediate >> 6) & GENMASK(9, 0)) == mm_jalr_op && 209 ip->r_format.rt == 31) 210 return 1; 211 return 0; 212 #else 213 if (ip->r_format.opcode == spec_op && 214 ip->r_format.func == jr_op && 215 ip->r_format.rs == 31) 216 return 1; 217 return 0; 218 #endif 219 } 220 221 static inline int is_ra_save_ins(union mips_instruction *ip, int *poff) 222 { 223 #ifdef CONFIG_CPU_MICROMIPS 224 /* 225 * swsp ra,offset 226 * swm16 reglist,offset(sp) 227 * swm32 reglist,offset(sp) 228 * sw32 ra,offset(sp) 229 * jradiussp - NOT SUPPORTED 230 * 231 * microMIPS is way more fun... 232 */ 233 if (mm_insn_16bit(ip->word >> 16)) { 234 switch (ip->mm16_r5_format.opcode) { 235 case mm_swsp16_op: 236 if (ip->mm16_r5_format.rt != 31) 237 return 0; 238 239 *poff = ip->mm16_r5_format.imm; 240 *poff = (*poff << 2) / sizeof(ulong); 241 return 1; 242 243 case mm_pool16c_op: 244 switch (ip->mm16_m_format.func) { 245 case mm_swm16_op: 246 *poff = ip->mm16_m_format.imm; 247 *poff += 1 + ip->mm16_m_format.rlist; 248 *poff = (*poff << 2) / sizeof(ulong); 249 return 1; 250 251 default: 252 return 0; 253 } 254 255 default: 256 return 0; 257 } 258 } 259 260 switch (ip->i_format.opcode) { 261 case mm_sw32_op: 262 if (ip->i_format.rs != 29) 263 return 0; 264 if (ip->i_format.rt != 31) 265 return 0; 266 267 *poff = ip->i_format.simmediate / sizeof(ulong); 268 return 1; 269 270 case mm_pool32b_op: 271 switch (ip->mm_m_format.func) { 272 case mm_swm32_func: 273 if (ip->mm_m_format.rd < 0x10) 274 return 0; 275 if (ip->mm_m_format.base != 29) 276 return 0; 277 278 *poff = ip->mm_m_format.simmediate; 279 *poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32); 280 *poff /= sizeof(ulong); 281 return 1; 282 default: 283 return 0; 284 } 285 286 default: 287 return 0; 288 } 289 #else 290 /* sw / sd $ra, offset($sp) */ 291 if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) && 292 ip->i_format.rs == 29 && ip->i_format.rt == 31) { 293 *poff = ip->i_format.simmediate / sizeof(ulong); 294 return 1; 295 } 296 #ifdef CONFIG_CPU_LOONGSON64 297 if ((ip->loongson3_lswc2_format.opcode == swc2_op) && 298 (ip->loongson3_lswc2_format.ls == 1) && 299 (ip->loongson3_lswc2_format.fr == 0) && 300 (ip->loongson3_lswc2_format.base == 29)) { 301 if (ip->loongson3_lswc2_format.rt == 31) { 302 *poff = ip->loongson3_lswc2_format.offset << 1; 303 return 1; 304 } 305 if (ip->loongson3_lswc2_format.rq == 31) { 306 *poff = (ip->loongson3_lswc2_format.offset << 1) + 1; 307 return 1; 308 } 309 } 310 #endif 311 return 0; 312 #endif 313 } 314 315 static inline int is_jump_ins(union mips_instruction *ip) 316 { 317 #ifdef CONFIG_CPU_MICROMIPS 318 /* 319 * jr16,jrc,jalr16,jalr16 320 * jal 321 * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb 322 * jraddiusp - NOT SUPPORTED 323 * 324 * microMIPS is kind of more fun... 325 */ 326 if (mm_insn_16bit(ip->word >> 16)) { 327 if ((ip->mm16_r5_format.opcode == mm_pool16c_op && 328 (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op)) 329 return 1; 330 return 0; 331 } 332 333 if (ip->j_format.opcode == mm_j32_op) 334 return 1; 335 if (ip->j_format.opcode == mm_jal32_op) 336 return 1; 337 if (ip->r_format.opcode != mm_pool32a_op || 338 ip->r_format.func != mm_pool32axf_op) 339 return 0; 340 return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op; 341 #else 342 if (ip->j_format.opcode == j_op) 343 return 1; 344 if (ip->j_format.opcode == jal_op) 345 return 1; 346 if (ip->r_format.opcode != spec_op) 347 return 0; 348 return ip->r_format.func == jalr_op || ip->r_format.func == jr_op; 349 #endif 350 } 351 352 static inline int is_sp_move_ins(union mips_instruction *ip, int *frame_size) 353 { 354 #ifdef CONFIG_CPU_MICROMIPS 355 unsigned short tmp; 356 357 /* 358 * addiusp -imm 359 * addius5 sp,-imm 360 * addiu32 sp,sp,-imm 361 * jradiussp - NOT SUPPORTED 362 * 363 * microMIPS is not more fun... 364 */ 365 if (mm_insn_16bit(ip->word >> 16)) { 366 if (ip->mm16_r3_format.opcode == mm_pool16d_op && 367 ip->mm16_r3_format.simmediate & mm_addiusp_func) { 368 tmp = ip->mm_b0_format.simmediate >> 1; 369 tmp = ((tmp & 0x1ff) ^ 0x100) - 0x100; 370 if ((tmp + 2) < 4) /* 0x0,0x1,0x1fe,0x1ff are special */ 371 tmp ^= 0x100; 372 *frame_size = -(signed short)(tmp << 2); 373 return 1; 374 } 375 if (ip->mm16_r5_format.opcode == mm_pool16d_op && 376 ip->mm16_r5_format.rt == 29) { 377 tmp = ip->mm16_r5_format.imm >> 1; 378 *frame_size = -(signed short)(tmp & 0xf); 379 return 1; 380 } 381 return 0; 382 } 383 384 if (ip->mm_i_format.opcode == mm_addiu32_op && 385 ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29) { 386 *frame_size = -ip->i_format.simmediate; 387 return 1; 388 } 389 #else 390 /* addiu/daddiu sp,sp,-imm */ 391 if (ip->i_format.rs != 29 || ip->i_format.rt != 29) 392 return 0; 393 394 if (ip->i_format.opcode == addiu_op || 395 ip->i_format.opcode == daddiu_op) { 396 *frame_size = -ip->i_format.simmediate; 397 return 1; 398 } 399 #endif 400 return 0; 401 } 402 403 static int get_frame_info(struct mips_frame_info *info) 404 { 405 bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS); 406 union mips_instruction insn, *ip, *ip_end; 407 unsigned int last_insn_size = 0; 408 bool saw_jump = false; 409 410 info->pc_offset = -1; 411 info->frame_size = 0; 412 413 ip = (void *)msk_isa16_mode((ulong)info->func); 414 if (!ip) 415 goto err; 416 417 ip_end = (void *)ip + (info->func_size ? info->func_size : 512); 418 419 while (ip < ip_end) { 420 ip = (void *)ip + last_insn_size; 421 422 if (is_mmips && mm_insn_16bit(ip->halfword[0])) { 423 insn.word = ip->halfword[0] << 16; 424 last_insn_size = 2; 425 } else if (is_mmips) { 426 insn.word = ip->halfword[0] << 16 | ip->halfword[1]; 427 last_insn_size = 4; 428 } else { 429 insn.word = ip->word; 430 last_insn_size = 4; 431 } 432 433 if (is_jr_ra_ins(ip)) { 434 break; 435 } else if (!info->frame_size) { 436 is_sp_move_ins(&insn, &info->frame_size); 437 continue; 438 } else if (!saw_jump && is_jump_ins(ip)) { 439 /* 440 * If we see a jump instruction, we are finished 441 * with the frame save. 442 * 443 * Some functions can have a shortcut return at 444 * the beginning of the function, so don't start 445 * looking for jump instruction until we see the 446 * frame setup. 447 * 448 * The RA save instruction can get put into the 449 * delay slot of the jump instruction, so look 450 * at the next instruction, too. 451 */ 452 saw_jump = true; 453 continue; 454 } 455 if (info->pc_offset == -1 && 456 is_ra_save_ins(&insn, &info->pc_offset)) 457 break; 458 if (saw_jump) 459 break; 460 } 461 if (info->frame_size && info->pc_offset >= 0) /* nested */ 462 return 0; 463 if (info->pc_offset < 0) /* leaf */ 464 return 1; 465 /* prologue seems bogus... */ 466 err: 467 return -1; 468 } 469 470 static struct mips_frame_info schedule_mfi __read_mostly; 471 472 #ifdef CONFIG_KALLSYMS 473 static unsigned long get___schedule_addr(void) 474 { 475 return kallsyms_lookup_name("__schedule"); 476 } 477 #else 478 static unsigned long get___schedule_addr(void) 479 { 480 union mips_instruction *ip = (void *)schedule; 481 int max_insns = 8; 482 int i; 483 484 for (i = 0; i < max_insns; i++, ip++) { 485 if (ip->j_format.opcode == j_op) 486 return J_TARGET(ip, ip->j_format.target); 487 } 488 return 0; 489 } 490 #endif 491 492 static int __init frame_info_init(void) 493 { 494 unsigned long size = 0; 495 #ifdef CONFIG_KALLSYMS 496 unsigned long ofs; 497 #endif 498 unsigned long addr; 499 500 addr = get___schedule_addr(); 501 if (!addr) 502 addr = (unsigned long)schedule; 503 504 #ifdef CONFIG_KALLSYMS 505 kallsyms_lookup_size_offset(addr, &size, &ofs); 506 #endif 507 schedule_mfi.func = (void *)addr; 508 schedule_mfi.func_size = size; 509 510 get_frame_info(&schedule_mfi); 511 512 /* 513 * Without schedule() frame info, result given by 514 * thread_saved_pc() and get_wchan() are not reliable. 515 */ 516 if (schedule_mfi.pc_offset < 0) 517 printk("Can't analyze schedule() prologue at %p\n", schedule); 518 519 return 0; 520 } 521 522 arch_initcall(frame_info_init); 523 524 /* 525 * Return saved PC of a blocked thread. 526 */ 527 static unsigned long thread_saved_pc(struct task_struct *tsk) 528 { 529 struct thread_struct *t = &tsk->thread; 530 531 /* New born processes are a special case */ 532 if (t->reg31 == (unsigned long) ret_from_fork) 533 return t->reg31; 534 if (schedule_mfi.pc_offset < 0) 535 return 0; 536 return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset]; 537 } 538 539 540 #ifdef CONFIG_KALLSYMS 541 /* generic stack unwinding function */ 542 unsigned long notrace unwind_stack_by_address(unsigned long stack_page, 543 unsigned long *sp, 544 unsigned long pc, 545 unsigned long *ra) 546 { 547 unsigned long low, high, irq_stack_high; 548 struct mips_frame_info info; 549 unsigned long size, ofs; 550 struct pt_regs *regs; 551 int leaf; 552 553 if (!stack_page) 554 return 0; 555 556 /* 557 * IRQ stacks start at IRQ_STACK_START 558 * task stacks at THREAD_SIZE - 32 559 */ 560 low = stack_page; 561 if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) { 562 high = stack_page + IRQ_STACK_START; 563 irq_stack_high = high; 564 } else { 565 high = stack_page + THREAD_SIZE - 32; 566 irq_stack_high = 0; 567 } 568 569 /* 570 * If we reached the top of the interrupt stack, start unwinding 571 * the interrupted task stack. 572 */ 573 if (unlikely(*sp == irq_stack_high)) { 574 unsigned long task_sp = *(unsigned long *)*sp; 575 576 /* 577 * Check that the pointer saved in the IRQ stack head points to 578 * something within the stack of the current task 579 */ 580 if (!object_is_on_stack((void *)task_sp)) 581 return 0; 582 583 /* 584 * Follow pointer to tasks kernel stack frame where interrupted 585 * state was saved. 586 */ 587 regs = (struct pt_regs *)task_sp; 588 pc = regs->cp0_epc; 589 if (!user_mode(regs) && __kernel_text_address(pc)) { 590 *sp = regs->regs[29]; 591 *ra = regs->regs[31]; 592 return pc; 593 } 594 return 0; 595 } 596 if (!kallsyms_lookup_size_offset(pc, &size, &ofs)) 597 return 0; 598 /* 599 * Return ra if an exception occurred at the first instruction 600 */ 601 if (unlikely(ofs == 0)) { 602 pc = *ra; 603 *ra = 0; 604 return pc; 605 } 606 607 info.func = (void *)(pc - ofs); 608 info.func_size = ofs; /* analyze from start to ofs */ 609 leaf = get_frame_info(&info); 610 if (leaf < 0) 611 return 0; 612 613 if (*sp < low || *sp + info.frame_size > high) 614 return 0; 615 616 if (leaf) 617 /* 618 * For some extreme cases, get_frame_info() can 619 * consider wrongly a nested function as a leaf 620 * one. In that cases avoid to return always the 621 * same value. 622 */ 623 pc = pc != *ra ? *ra : 0; 624 else 625 pc = ((unsigned long *)(*sp))[info.pc_offset]; 626 627 *sp += info.frame_size; 628 *ra = 0; 629 return __kernel_text_address(pc) ? pc : 0; 630 } 631 EXPORT_SYMBOL(unwind_stack_by_address); 632 633 /* used by show_backtrace() */ 634 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp, 635 unsigned long pc, unsigned long *ra) 636 { 637 unsigned long stack_page = 0; 638 int cpu; 639 640 for_each_possible_cpu(cpu) { 641 if (on_irq_stack(cpu, *sp)) { 642 stack_page = (unsigned long)irq_stack[cpu]; 643 break; 644 } 645 } 646 647 if (!stack_page) 648 stack_page = (unsigned long)task_stack_page(task); 649 650 return unwind_stack_by_address(stack_page, sp, pc, ra); 651 } 652 #endif 653 654 /* 655 * get_wchan - a maintenance nightmare^W^Wpain in the ass ... 656 */ 657 unsigned long get_wchan(struct task_struct *task) 658 { 659 unsigned long pc = 0; 660 #ifdef CONFIG_KALLSYMS 661 unsigned long sp; 662 unsigned long ra = 0; 663 #endif 664 665 if (!task || task == current || task->state == TASK_RUNNING) 666 goto out; 667 if (!task_stack_page(task)) 668 goto out; 669 670 pc = thread_saved_pc(task); 671 672 #ifdef CONFIG_KALLSYMS 673 sp = task->thread.reg29 + schedule_mfi.frame_size; 674 675 while (in_sched_functions(pc)) 676 pc = unwind_stack(task, &sp, pc, &ra); 677 #endif 678 679 out: 680 return pc; 681 } 682 683 unsigned long mips_stack_top(void) 684 { 685 unsigned long top = TASK_SIZE & PAGE_MASK; 686 687 if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) { 688 /* One page for branch delay slot "emulation" */ 689 top -= PAGE_SIZE; 690 } 691 692 /* Space for the VDSO, data page & GIC user page */ 693 top -= PAGE_ALIGN(current->thread.abi->vdso->size); 694 top -= PAGE_SIZE; 695 top -= mips_gic_present() ? PAGE_SIZE : 0; 696 697 /* Space for cache colour alignment */ 698 if (cpu_has_dc_aliases) 699 top -= shm_align_mask + 1; 700 701 /* Space to randomize the VDSO base */ 702 if (current->flags & PF_RANDOMIZE) 703 top -= VDSO_RANDOMIZE_SIZE; 704 705 return top; 706 } 707 708 /* 709 * Don't forget that the stack pointer must be aligned on a 8 bytes 710 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI. 711 */ 712 unsigned long arch_align_stack(unsigned long sp) 713 { 714 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 715 sp -= get_random_int() & ~PAGE_MASK; 716 717 return sp & ALMASK; 718 } 719 720 static struct cpumask backtrace_csd_busy; 721 722 static void handle_backtrace(void *info) 723 { 724 nmi_cpu_backtrace(get_irq_regs()); 725 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy); 726 } 727 728 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd) = 729 CSD_INIT(handle_backtrace, NULL); 730 731 static void raise_backtrace(cpumask_t *mask) 732 { 733 call_single_data_t *csd; 734 int cpu; 735 736 for_each_cpu(cpu, mask) { 737 /* 738 * If we previously sent an IPI to the target CPU & it hasn't 739 * cleared its bit in the busy cpumask then it didn't handle 740 * our previous IPI & it's not safe for us to reuse the 741 * call_single_data_t. 742 */ 743 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) { 744 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n", 745 cpu); 746 continue; 747 } 748 749 csd = &per_cpu(backtrace_csd, cpu); 750 smp_call_function_single_async(cpu, csd); 751 } 752 } 753 754 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) 755 { 756 nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace); 757 } 758 759 int mips_get_process_fp_mode(struct task_struct *task) 760 { 761 int value = 0; 762 763 if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS)) 764 value |= PR_FP_MODE_FR; 765 if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS)) 766 value |= PR_FP_MODE_FRE; 767 768 return value; 769 } 770 771 static long prepare_for_fp_mode_switch(void *unused) 772 { 773 /* 774 * This is icky, but we use this to simply ensure that all CPUs have 775 * context switched, regardless of whether they were previously running 776 * kernel or user code. This ensures that no CPU that a mode-switching 777 * program may execute on keeps its FPU enabled (& in the old mode) 778 * throughout the mode switch. 779 */ 780 return 0; 781 } 782 783 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value) 784 { 785 const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE; 786 struct task_struct *t; 787 struct cpumask process_cpus; 788 int cpu; 789 790 /* If nothing to change, return right away, successfully. */ 791 if (value == mips_get_process_fp_mode(task)) 792 return 0; 793 794 /* Only accept a mode change if 64-bit FP enabled for o32. */ 795 if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT)) 796 return -EOPNOTSUPP; 797 798 /* And only for o32 tasks. */ 799 if (IS_ENABLED(CONFIG_64BIT) && !test_thread_flag(TIF_32BIT_REGS)) 800 return -EOPNOTSUPP; 801 802 /* Check the value is valid */ 803 if (value & ~known_bits) 804 return -EOPNOTSUPP; 805 806 /* Setting FRE without FR is not supported. */ 807 if ((value & (PR_FP_MODE_FR | PR_FP_MODE_FRE)) == PR_FP_MODE_FRE) 808 return -EOPNOTSUPP; 809 810 /* Avoid inadvertently triggering emulation */ 811 if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu && 812 !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64)) 813 return -EOPNOTSUPP; 814 if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre) 815 return -EOPNOTSUPP; 816 817 /* FR = 0 not supported in MIPS R6 */ 818 if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6) 819 return -EOPNOTSUPP; 820 821 /* Indicate the new FP mode in each thread */ 822 for_each_thread(task, t) { 823 /* Update desired FP register width */ 824 if (value & PR_FP_MODE_FR) { 825 clear_tsk_thread_flag(t, TIF_32BIT_FPREGS); 826 } else { 827 set_tsk_thread_flag(t, TIF_32BIT_FPREGS); 828 clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE); 829 } 830 831 /* Update desired FP single layout */ 832 if (value & PR_FP_MODE_FRE) 833 set_tsk_thread_flag(t, TIF_HYBRID_FPREGS); 834 else 835 clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS); 836 } 837 838 /* 839 * We need to ensure that all threads in the process have switched mode 840 * before returning, in order to allow userland to not worry about 841 * races. We can do this by forcing all CPUs that any thread in the 842 * process may be running on to schedule something else - in this case 843 * prepare_for_fp_mode_switch(). 844 * 845 * We begin by generating a mask of all CPUs that any thread in the 846 * process may be running on. 847 */ 848 cpumask_clear(&process_cpus); 849 for_each_thread(task, t) 850 cpumask_set_cpu(task_cpu(t), &process_cpus); 851 852 /* 853 * Now we schedule prepare_for_fp_mode_switch() on each of those CPUs. 854 * 855 * The CPUs may have rescheduled already since we switched mode or 856 * generated the cpumask, but that doesn't matter. If the task in this 857 * process is scheduled out then our scheduling 858 * prepare_for_fp_mode_switch() will simply be redundant. If it's 859 * scheduled in then it will already have picked up the new FP mode 860 * whilst doing so. 861 */ 862 get_online_cpus(); 863 for_each_cpu_and(cpu, &process_cpus, cpu_online_mask) 864 work_on_cpu(cpu, prepare_for_fp_mode_switch, NULL); 865 put_online_cpus(); 866 867 return 0; 868 } 869 870 #if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32) 871 void mips_dump_regs32(u32 *uregs, const struct pt_regs *regs) 872 { 873 unsigned int i; 874 875 for (i = MIPS32_EF_R1; i <= MIPS32_EF_R31; i++) { 876 /* k0/k1 are copied as zero. */ 877 if (i == MIPS32_EF_R26 || i == MIPS32_EF_R27) 878 uregs[i] = 0; 879 else 880 uregs[i] = regs->regs[i - MIPS32_EF_R0]; 881 } 882 883 uregs[MIPS32_EF_LO] = regs->lo; 884 uregs[MIPS32_EF_HI] = regs->hi; 885 uregs[MIPS32_EF_CP0_EPC] = regs->cp0_epc; 886 uregs[MIPS32_EF_CP0_BADVADDR] = regs->cp0_badvaddr; 887 uregs[MIPS32_EF_CP0_STATUS] = regs->cp0_status; 888 uregs[MIPS32_EF_CP0_CAUSE] = regs->cp0_cause; 889 } 890 #endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */ 891 892 #ifdef CONFIG_64BIT 893 void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs) 894 { 895 unsigned int i; 896 897 for (i = MIPS64_EF_R1; i <= MIPS64_EF_R31; i++) { 898 /* k0/k1 are copied as zero. */ 899 if (i == MIPS64_EF_R26 || i == MIPS64_EF_R27) 900 uregs[i] = 0; 901 else 902 uregs[i] = regs->regs[i - MIPS64_EF_R0]; 903 } 904 905 uregs[MIPS64_EF_LO] = regs->lo; 906 uregs[MIPS64_EF_HI] = regs->hi; 907 uregs[MIPS64_EF_CP0_EPC] = regs->cp0_epc; 908 uregs[MIPS64_EF_CP0_BADVADDR] = regs->cp0_badvaddr; 909 uregs[MIPS64_EF_CP0_STATUS] = regs->cp0_status; 910 uregs[MIPS64_EF_CP0_CAUSE] = regs->cp0_cause; 911 } 912 #endif /* CONFIG_64BIT */ 913