arch/mips/kernel/process.c

   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/dsemul.h>
  34 #include <asm/dsp.h>
  35 #include <asm/fpu.h>
  36 #include <asm/irq.h>
  37 #include <asm/msa.h>
  38 #include <asm/pgtable.h>
  39 #include <asm/mipsregs.h>
  40 #include <asm/processor.h>
  41 #include <asm/reg.h>
  42 #include <asm/uaccess.h>
  43 #include <asm/io.h>
  44 #include <asm/elf.h>
  45 #include <asm/isadep.h>
  46 #include <asm/inst.h>
  47 #include <asm/stacktrace.h>
  48 #include <asm/irq_regs.h>
  49
  50 #ifdef CONFIG_HOTPLUG_CPU
  51 void arch_cpu_idle_dead(void)
  52 {
  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         atomic_set(&current->thread.bd_emu_frame, BD_EMUFRAME_NONE);
  72         init_dsp();
  73         regs->cp0_epc = pc;
  74         regs->regs[29] = sp;
  75 }
  76
  77 void exit_thread(struct task_struct *tsk)
  78 {
  79         /*
  80          * User threads may have allocated a delay slot emulation frame.
  81          * If so, clean up that allocation.
  82          */
  83         if (!(current->flags & PF_KTHREAD))
  84                 dsemul_thread_cleanup(tsk);
  85 }
  86
  87 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  88 {
  89         /*
  90          * Save any process state which is live in hardware registers to the
  91          * parent context prior to duplication. This prevents the new child
  92          * state becoming stale if the parent is preempted before copy_thread()
  93          * gets a chance to save the parent's live hardware registers to the
  94          * child context.
  95          */
  96         preempt_disable();
  97
  98         if (is_msa_enabled())
  99                 save_msa(current);
 100         else if (is_fpu_owner())
 101                 _save_fp(current);
 102
 103         save_dsp(current);
 104
 105         preempt_enable();
 106
 107         *dst = *src;
 108         return 0;
 109 }
 110
 111 /*
 112  * Copy architecture-specific thread state
 113  */
 114 int copy_thread(unsigned long clone_flags, unsigned long usp,
 115         unsigned long kthread_arg, struct task_struct *p)
 116 {
 117         struct thread_info *ti = task_thread_info(p);
 118         struct pt_regs *childregs, *regs = current_pt_regs();
 119         unsigned long childksp;
 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         atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
 173
 174         if (clone_flags & CLONE_SETTLS)
 175                 ti->tp_value = regs->regs[7];
 176
 177         return 0;
 178 }
 179
 180 #ifdef CONFIG_CC_STACKPROTECTOR
 181 #include <linux/stackprotector.h>
 182 unsigned long __stack_chk_guard __read_mostly;
 183 EXPORT_SYMBOL(__stack_chk_guard);
 184 #endif
 185
 186 struct mips_frame_info {
 187         void            *func;
 188         unsigned long   func_size;
 189         int             frame_size;
 190         int             pc_offset;
 191 };
 192
 193 #define J_TARGET(pc,target)     \
 194                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 195
 196 static inline int is_ra_save_ins(union mips_instruction *ip, int *poff)
 197 {
 198 #ifdef CONFIG_CPU_MICROMIPS
 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[1])) {
 209                 switch (ip->mm16_r5_format.opcode) {
 210                 case mm_swsp16_op:
 211                         if (ip->mm16_r5_format.rt != 31)
 212                                 return 0;
 213
 214                         *poff = ip->mm16_r5_format.simmediate;
 215                         *poff = (*poff << 2) / sizeof(ulong);
 216                         return 1;
 217
 218                 case mm_pool16c_op:
 219                         switch (ip->mm16_m_format.func) {
 220                         case mm_swm16_op:
 221                                 *poff = ip->mm16_m_format.imm;
 222                                 *poff += 1 + ip->mm16_m_format.rlist;
 223                                 *poff = (*poff << 2) / sizeof(ulong);
 224                                 return 1;
 225
 226                         default:
 227                                 return 0;
 228                         }
 229
 230                 default:
 231                         return 0;
 232                 }
 233         }
 234
 235         switch (ip->i_format.opcode) {
 236         case mm_sw32_op:
 237                 if (ip->i_format.rs != 29)
 238                         return 0;
 239                 if (ip->i_format.rt != 31)
 240                         return 0;
 241
 242                 *poff = ip->i_format.simmediate / sizeof(ulong);
 243                 return 1;
 244
 245         case mm_pool32b_op:
 246                 switch (ip->mm_m_format.func) {
 247                 case mm_swm32_func:
 248                         if (ip->mm_m_format.rd < 0x10)
 249                                 return 0;
 250                         if (ip->mm_m_format.base != 29)
 251                                 return 0;
 252
 253                         *poff = ip->mm_m_format.simmediate;
 254                         *poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32);
 255                         *poff /= sizeof(ulong);
 256                         return 1;
 257                 default:
 258                         return 0;
 259                 }
 260
 261         default:
 262                 return 0;
 263         }
 264 #else
 265         /* sw / sd $ra, offset($sp) */
 266         if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 267                 ip->i_format.rs == 29 && ip->i_format.rt == 31) {
 268                 *poff = ip->i_format.simmediate / sizeof(ulong);
 269                 return 1;
 270         }
 271
 272         return 0;
 273 #endif
 274 }
 275
 276 static inline int is_jump_ins(union mips_instruction *ip)
 277 {
 278 #ifdef CONFIG_CPU_MICROMIPS
 279         /*
 280          * jr16,jrc,jalr16,jalr16
 281          * jal
 282          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 283          * jraddiusp - NOT SUPPORTED
 284          *
 285          * microMIPS is kind of more fun...
 286          */
 287         if (mm_insn_16bit(ip->halfword[1])) {
 288                 if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
 289                     (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op))
 290                         return 1;
 291                 return 0;
 292         }
 293
 294         if (ip->j_format.opcode == mm_j32_op)
 295                 return 1;
 296         if (ip->j_format.opcode == mm_jal32_op)
 297                 return 1;
 298         if (ip->r_format.opcode != mm_pool32a_op ||
 299                         ip->r_format.func != mm_pool32axf_op)
 300                 return 0;
 301         return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 302 #else
 303         if (ip->j_format.opcode == j_op)
 304                 return 1;
 305         if (ip->j_format.opcode == jal_op)
 306                 return 1;
 307         if (ip->r_format.opcode != spec_op)
 308                 return 0;
 309         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 310 #endif
 311 }
 312
 313 static inline int is_sp_move_ins(union mips_instruction *ip)
 314 {
 315 #ifdef CONFIG_CPU_MICROMIPS
 316         /*
 317          * addiusp -imm
 318          * addius5 sp,-imm
 319          * addiu32 sp,sp,-imm
 320          * jradiussp - NOT SUPPORTED
 321          *
 322          * microMIPS is not more fun...
 323          */
 324         if (mm_insn_16bit(ip->halfword[1])) {
 325                 return (ip->mm16_r3_format.opcode == mm_pool16d_op &&
 326                         ip->mm16_r3_format.simmediate && mm_addiusp_func) ||
 327                        (ip->mm16_r5_format.opcode == mm_pool16d_op &&
 328                         ip->mm16_r5_format.rt == 29);
 329         }
 330
 331         return ip->mm_i_format.opcode == mm_addiu32_op &&
 332                ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
 333 #else
 334         /* addiu/daddiu sp,sp,-imm */
 335         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 336                 return 0;
 337         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 338                 return 1;
 339 #endif
 340         return 0;
 341 }
 342
 343 static int get_frame_info(struct mips_frame_info *info)
 344 {
 345         bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
 346         union mips_instruction insn, *ip, *ip_end;
 347         const unsigned int max_insns = 128;
 348         unsigned int i;
 349
 350         info->pc_offset = -1;
 351         info->frame_size = 0;
 352
 353         ip = (void *)msk_isa16_mode((ulong)info->func);
 354         if (!ip)
 355                 goto err;
 356
 357         ip_end = (void *)ip + info->func_size;
 358
 359         for (i = 0; i < max_insns && ip < ip_end; i++, ip++) {
 360                 if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
 361                         insn.halfword[0] = 0;
 362                         insn.halfword[1] = ip->halfword[0];
 363                 } else if (is_mmips) {
 364                         insn.halfword[0] = ip->halfword[1];
 365                         insn.halfword[1] = ip->halfword[0];
 366                 } else {
 367                         insn.word = ip->word;
 368                 }
 369
 370                 if (is_jump_ins(&insn))
 371                         break;
 372
 373                 if (!info->frame_size) {
 374                         if (is_sp_move_ins(&insn))
 375                         {
 376 #ifdef CONFIG_CPU_MICROMIPS
 377                                 if (mm_insn_16bit(ip->halfword[0]))
 378                                 {
 379                                         unsigned short tmp;
 380
 381                                         if (ip->halfword[0] & mm_addiusp_func)
 382                                         {
 383                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 384                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 385                                         } else {
 386                                                 tmp = (ip->halfword[0] >> 1);
 387                                                 info->frame_size = -(signed short)(tmp & 0xf);
 388                                         }
 389                                         ip = (void *) &ip->halfword[1];
 390                                         ip--;
 391                                 } else
 392 #endif
 393                                 info->frame_size = - ip->i_format.simmediate;
 394                         }
 395                         continue;
 396                 }
 397                 if (info->pc_offset == -1 &&
 398                     is_ra_save_ins(&insn, &info->pc_offset))
 399                         break;
 400         }
 401         if (info->frame_size && info->pc_offset >= 0) /* nested */
 402                 return 0;
 403         if (info->pc_offset < 0) /* leaf */
 404                 return 1;
 405         /* prologue seems boggus... */
 406 err:
 407         return -1;
 408 }
 409
 410 static struct mips_frame_info schedule_mfi __read_mostly;
 411
 412 #ifdef CONFIG_KALLSYMS
 413 static unsigned long get___schedule_addr(void)
 414 {
 415         return kallsyms_lookup_name("__schedule");
 416 }
 417 #else
 418 static unsigned long get___schedule_addr(void)
 419 {
 420         union mips_instruction *ip = (void *)schedule;
 421         int max_insns = 8;
 422         int i;
 423
 424         for (i = 0; i < max_insns; i++, ip++) {
 425                 if (ip->j_format.opcode == j_op)
 426                         return J_TARGET(ip, ip->j_format.target);
 427         }
 428         return 0;
 429 }
 430 #endif
 431
 432 static int __init frame_info_init(void)
 433 {
 434         unsigned long size = 0;
 435 #ifdef CONFIG_KALLSYMS
 436         unsigned long ofs;
 437 #endif
 438         unsigned long addr;
 439
 440         addr = get___schedule_addr();
 441         if (!addr)
 442                 addr = (unsigned long)schedule;
 443
 444 #ifdef CONFIG_KALLSYMS
 445         kallsyms_lookup_size_offset(addr, &size, &ofs);
 446 #endif
 447         schedule_mfi.func = (void *)addr;
 448         schedule_mfi.func_size = size;
 449
 450         get_frame_info(&schedule_mfi);
 451
 452         /*
 453          * Without schedule() frame info, result given by
 454          * thread_saved_pc() and get_wchan() are not reliable.
 455          */
 456         if (schedule_mfi.pc_offset < 0)
 457                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 458
 459         return 0;
 460 }
 461
 462 arch_initcall(frame_info_init);
 463
 464 /*
 465  * Return saved PC of a blocked thread.
 466  */
 467 unsigned long thread_saved_pc(struct task_struct *tsk)
 468 {
 469         struct thread_struct *t = &tsk->thread;
 470
 471         /* New born processes are a special case */
 472         if (t->reg31 == (unsigned long) ret_from_fork)
 473                 return t->reg31;
 474         if (schedule_mfi.pc_offset < 0)
 475                 return 0;
 476         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 477 }
 478
 479
 480 #ifdef CONFIG_KALLSYMS
 481 /* generic stack unwinding function */
 482 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 483                                               unsigned long *sp,
 484                                               unsigned long pc,
 485                                               unsigned long *ra)
 486 {
 487         unsigned long low, high, irq_stack_high;
 488         struct mips_frame_info info;
 489         unsigned long size, ofs;
 490         struct pt_regs *regs;
 491         int leaf;
 492
 493         if (!stack_page)
 494                 return 0;
 495
 496         /*
 497          * IRQ stacks start at IRQ_STACK_START
 498          * task stacks at THREAD_SIZE - 32
 499          */
 500         low = stack_page;
 501         if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) {
 502                 high = stack_page + IRQ_STACK_START;
 503                 irq_stack_high = high;
 504         } else {
 505                 high = stack_page + THREAD_SIZE - 32;
 506                 irq_stack_high = 0;
 507         }
 508
 509         /*
 510          * If we reached the top of the interrupt stack, start unwinding
 511          * the interrupted task stack.
 512          */
 513         if (unlikely(*sp == irq_stack_high)) {
 514                 unsigned long task_sp = *(unsigned long *)*sp;
 515
 516                 /*
 517                  * Check that the pointer saved in the IRQ stack head points to
 518                  * something within the stack of the current task
 519                  */
 520                 if (!object_is_on_stack((void *)task_sp))
 521                         return 0;
 522
 523                 /*
 524                  * Follow pointer to tasks kernel stack frame where interrupted
 525                  * state was saved.
 526                  */
 527                 regs = (struct pt_regs *)task_sp;
 528                 pc = regs->cp0_epc;
 529                 if (!user_mode(regs) && __kernel_text_address(pc)) {
 530                         *sp = regs->regs[29];
 531                         *ra = regs->regs[31];
 532                         return pc;
 533                 }
 534                 return 0;
 535         }
 536         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 537                 return 0;
 538         /*
 539          * Return ra if an exception occurred at the first instruction
 540          */
 541         if (unlikely(ofs == 0)) {
 542                 pc = *ra;
 543                 *ra = 0;
 544                 return pc;
 545         }
 546
 547         info.func = (void *)(pc - ofs);
 548         info.func_size = ofs;   /* analyze from start to ofs */
 549         leaf = get_frame_info(&info);
 550         if (leaf < 0)
 551                 return 0;
 552
 553         if (*sp < low || *sp + info.frame_size > high)
 554                 return 0;
 555
 556         if (leaf)
 557                 /*
 558                  * For some extreme cases, get_frame_info() can
 559                  * consider wrongly a nested function as a leaf
 560                  * one. In that cases avoid to return always the
 561                  * same value.
 562                  */
 563                 pc = pc != *ra ? *ra : 0;
 564         else
 565                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 566
 567         *sp += info.frame_size;
 568         *ra = 0;
 569         return __kernel_text_address(pc) ? pc : 0;
 570 }
 571 EXPORT_SYMBOL(unwind_stack_by_address);
 572
 573 /* used by show_backtrace() */
 574 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 575                            unsigned long pc, unsigned long *ra)
 576 {
 577         unsigned long stack_page = 0;
 578         int cpu;
 579
 580         for_each_possible_cpu(cpu) {
 581                 if (on_irq_stack(cpu, *sp)) {
 582                         stack_page = (unsigned long)irq_stack[cpu];
 583                         break;
 584                 }
 585         }
 586
 587         if (!stack_page)
 588                 stack_page = (unsigned long)task_stack_page(task);
 589
 590         return unwind_stack_by_address(stack_page, sp, pc, ra);
 591 }
 592 #endif
 593
 594 /*
 595  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 596  */
 597 unsigned long get_wchan(struct task_struct *task)
 598 {
 599         unsigned long pc = 0;
 600 #ifdef CONFIG_KALLSYMS
 601         unsigned long sp;
 602         unsigned long ra = 0;
 603 #endif
 604
 605         if (!task || task == current || task->state == TASK_RUNNING)
 606                 goto out;
 607         if (!task_stack_page(task))
 608                 goto out;
 609
 610         pc = thread_saved_pc(task);
 611
 612 #ifdef CONFIG_KALLSYMS
 613         sp = task->thread.reg29 + schedule_mfi.frame_size;
 614
 615         while (in_sched_functions(pc))
 616                 pc = unwind_stack(task, &sp, pc, &ra);
 617 #endif
 618
 619 out:
 620         return pc;
 621 }
 622
 623 /*
 624  * Don't forget that the stack pointer must be aligned on a 8 bytes
 625  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 626  */
 627 unsigned long arch_align_stack(unsigned long sp)
 628 {
 629         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 630                 sp -= get_random_int() & ~PAGE_MASK;
 631
 632         return sp & ALMASK;
 633 }
 634
 635 static DEFINE_PER_CPU(struct call_single_data, backtrace_csd);
 636 static struct cpumask backtrace_csd_busy;
 637
 638 static void arch_dump_stack(void *info)
 639 {
 640         struct pt_regs *regs;
 641         static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
 642
 643         arch_spin_lock(&lock);
 644         regs = get_irq_regs();
 645
 646         if (regs)
 647                 show_regs(regs);
 648         else
 649                 dump_stack();
 650         arch_spin_unlock(&lock);
 651
 652         cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
 653 }
 654
 655 void arch_trigger_all_cpu_backtrace(bool include_self)
 656 {
 657         struct call_single_data *csd;
 658         int cpu;
 659
 660         for_each_cpu(cpu, cpu_online_mask) {
 661                 /*
 662                  * If we previously sent an IPI to the target CPU & it hasn't
 663                  * cleared its bit in the busy cpumask then it didn't handle
 664                  * our previous IPI & it's not safe for us to reuse the
 665                  * call_single_data_t.
 666                  */
 667                 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
 668                         pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
 669                                 cpu);
 670                         continue;
 671                 }
 672
 673                 csd = &per_cpu(backtrace_csd, cpu);
 674                 csd->func = arch_dump_stack;
 675                 smp_call_function_single_async(cpu, csd);
 676         }
 677 }
 678
 679 int mips_get_process_fp_mode(struct task_struct *task)
 680 {
 681         int value = 0;
 682
 683         if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
 684                 value |= PR_FP_MODE_FR;
 685         if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
 686                 value |= PR_FP_MODE_FRE;
 687
 688         return value;
 689 }
 690
 691 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 692 {
 693         const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
 694         unsigned long switch_count;
 695         struct task_struct *t;
 696
 697         /* If nothing to change, return right away, successfully.  */
 698         if (value == mips_get_process_fp_mode(task))
 699                 return 0;
 700
 701         /* Only accept a mode change if 64-bit FP enabled for o32.  */
 702         if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
 703                 return -EOPNOTSUPP;
 704
 705         /* And only for o32 tasks.  */
 706         if (IS_ENABLED(CONFIG_64BIT) && !test_thread_flag(TIF_32BIT_REGS))
 707                 return -EOPNOTSUPP;
 708
 709         /* Check the value is valid */
 710         if (value & ~known_bits)
 711                 return -EOPNOTSUPP;
 712
 713         /* Setting FRE without FR is not supported.  */
 714         if ((value & (PR_FP_MODE_FR | PR_FP_MODE_FRE)) == PR_FP_MODE_FRE)
 715                 return -EOPNOTSUPP;
 716
 717         /* Avoid inadvertently triggering emulation */
 718         if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
 719             !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
 720                 return -EOPNOTSUPP;
 721         if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
 722                 return -EOPNOTSUPP;
 723
 724         /* FR = 0 not supported in MIPS R6 */
 725         if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
 726                 return -EOPNOTSUPP;
 727
 728         /* Proceed with the mode switch */
 729         preempt_disable();
 730
 731         /* Save FP & vector context, then disable FPU & MSA */
 732         if (task->signal == current->signal)
 733                 lose_fpu(1);
 734
 735         /* Prevent any threads from obtaining live FP context */
 736         atomic_set(&task->mm->context.fp_mode_switching, 1);
 737         smp_mb__after_atomic();
 738
 739         /*
 740          * If there are multiple online CPUs then wait until all threads whose
 741          * FP mode is about to change have been context switched. This approach
 742          * allows us to only worry about whether an FP mode switch is in
 743          * progress when FP is first used in a tasks time slice. Pretty much all
 744          * of the mode switch overhead can thus be confined to cases where mode
 745          * switches are actually occurring. That is, to here. However for the
 746          * thread performing the mode switch it may take a while...
 747          */
 748         if (num_online_cpus() > 1) {
 749                 spin_lock_irq(&task->sighand->siglock);
 750
 751                 for_each_thread(task, t) {
 752                         if (t == current)
 753                                 continue;
 754
 755                         switch_count = t->nvcsw + t->nivcsw;
 756
 757                         do {
 758                                 spin_unlock_irq(&task->sighand->siglock);
 759                                 cond_resched();
 760                                 spin_lock_irq(&task->sighand->siglock);
 761                         } while ((t->nvcsw + t->nivcsw) == switch_count);
 762                 }
 763
 764                 spin_unlock_irq(&task->sighand->siglock);
 765         }
 766
 767         /*
 768          * There are now no threads of the process with live FP context, so it
 769          * is safe to proceed with the FP mode switch.
 770          */
 771         for_each_thread(task, t) {
 772                 /* Update desired FP register width */
 773                 if (value & PR_FP_MODE_FR) {
 774                         clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 775                 } else {
 776                         set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 777                         clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
 778                 }
 779
 780                 /* Update desired FP single layout */
 781                 if (value & PR_FP_MODE_FRE)
 782                         set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 783                 else
 784                         clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 785         }
 786
 787         /* Allow threads to use FP again */
 788         atomic_set(&task->mm->context.fp_mode_switching, 0);
 789         preempt_enable();
 790
 791         return 0;
 792 }