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/sched/debug.h>
  15 #include <linux/sched/task.h>
  16 #include <linux/sched/task_stack.h>
  17 #include <linux/tick.h>
  18 #include <linux/kernel.h>
  19 #include <linux/mm.h>
  20 #include <linux/stddef.h>
  21 #include <linux/unistd.h>
  22 #include <linux/export.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/mman.h>
  25 #include <linux/personality.h>
  26 #include <linux/sys.h>
  27 #include <linux/init.h>
  28 #include <linux/completion.h>
  29 #include <linux/kallsyms.h>
  30 #include <linux/random.h>
  31 #include <linux/prctl.h>
  32
  33 #include <asm/asm.h>
  34 #include <asm/bootinfo.h>
  35 #include <asm/cpu.h>
  36 #include <asm/dsemul.h>
  37 #include <asm/dsp.h>
  38 #include <asm/fpu.h>
  39 #include <asm/irq.h>
  40 #include <asm/msa.h>
  41 #include <asm/pgtable.h>
  42 #include <asm/mipsregs.h>
  43 #include <asm/processor.h>
  44 #include <asm/reg.h>
  45 #include <linux/uaccess.h>
  46 #include <asm/io.h>
  47 #include <asm/elf.h>
  48 #include <asm/isadep.h>
  49 #include <asm/inst.h>
  50 #include <asm/stacktrace.h>
  51 #include <asm/irq_regs.h>
  52
  53 #ifdef CONFIG_HOTPLUG_CPU
  54 void arch_cpu_idle_dead(void)
  55 {
  56         play_dead();
  57 }
  58 #endif
  59
  60 asmlinkage void ret_from_fork(void);
  61 asmlinkage void ret_from_kernel_thread(void);
  62
  63 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  64 {
  65         unsigned long status;
  66
  67         /* New thread loses kernel privileges. */
  68         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
  69         status |= KU_USER;
  70         regs->cp0_status = status;
  71         lose_fpu(0);
  72         clear_thread_flag(TIF_MSA_CTX_LIVE);
  73         clear_used_math();
  74         atomic_set(&current->thread.bd_emu_frame, BD_EMUFRAME_NONE);
  75         init_dsp();
  76         regs->cp0_epc = pc;
  77         regs->regs[29] = sp;
  78 }
  79
  80 void exit_thread(struct task_struct *tsk)
  81 {
  82         /*
  83          * User threads may have allocated a delay slot emulation frame.
  84          * If so, clean up that allocation.
  85          */
  86         if (!(current->flags & PF_KTHREAD))
  87                 dsemul_thread_cleanup(tsk);
  88 }
  89
  90 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  91 {
  92         /*
  93          * Save any process state which is live in hardware registers to the
  94          * parent context prior to duplication. This prevents the new child
  95          * state becoming stale if the parent is preempted before copy_thread()
  96          * gets a chance to save the parent's live hardware registers to the
  97          * child context.
  98          */
  99         preempt_disable();
 100
 101         if (is_msa_enabled())
 102                 save_msa(current);
 103         else if (is_fpu_owner())
 104                 _save_fp(current);
 105
 106         save_dsp(current);
 107
 108         preempt_enable();
 109
 110         *dst = *src;
 111         return 0;
 112 }
 113
 114 /*
 115  * Copy architecture-specific thread state
 116  */
 117 int copy_thread_tls(unsigned long clone_flags, unsigned long usp,
 118         unsigned long kthread_arg, struct task_struct *p, unsigned long tls)
 119 {
 120         struct thread_info *ti = task_thread_info(p);
 121         struct pt_regs *childregs, *regs = current_pt_regs();
 122         unsigned long childksp;
 123         p->set_child_tid = p->clear_child_tid = NULL;
 124
 125         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 126
 127         /* set up new TSS. */
 128         childregs = (struct pt_regs *) childksp - 1;
 129         /*  Put the stack after the struct pt_regs.  */
 130         childksp = (unsigned long) childregs;
 131         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 132         if (unlikely(p->flags & PF_KTHREAD)) {
 133                 /* kernel thread */
 134                 unsigned long status = p->thread.cp0_status;
 135                 memset(childregs, 0, sizeof(struct pt_regs));
 136                 ti->addr_limit = KERNEL_DS;
 137                 p->thread.reg16 = usp; /* fn */
 138                 p->thread.reg17 = kthread_arg;
 139                 p->thread.reg29 = childksp;
 140                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 141 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 142                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 143                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 144 #else
 145                 status |= ST0_EXL;
 146 #endif
 147                 childregs->cp0_status = status;
 148                 return 0;
 149         }
 150
 151         /* user thread */
 152         *childregs = *regs;
 153         childregs->regs[7] = 0; /* Clear error flag */
 154         childregs->regs[2] = 0; /* Child gets zero as return value */
 155         if (usp)
 156                 childregs->regs[29] = usp;
 157         ti->addr_limit = USER_DS;
 158
 159         p->thread.reg29 = (unsigned long) childregs;
 160         p->thread.reg31 = (unsigned long) ret_from_fork;
 161
 162         /*
 163          * New tasks lose permission to use the fpu. This accelerates context
 164          * switching for most programs since they don't use the fpu.
 165          */
 166         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 167
 168         clear_tsk_thread_flag(p, TIF_USEDFPU);
 169         clear_tsk_thread_flag(p, TIF_USEDMSA);
 170         clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
 171
 172 #ifdef CONFIG_MIPS_MT_FPAFF
 173         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 174 #endif /* CONFIG_MIPS_MT_FPAFF */
 175
 176         atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
 177
 178         if (clone_flags & CLONE_SETTLS)
 179                 ti->tp_value = tls;
 180
 181         return 0;
 182 }
 183
 184 #ifdef CONFIG_CC_STACKPROTECTOR
 185 #include <linux/stackprotector.h>
 186 unsigned long __stack_chk_guard __read_mostly;
 187 EXPORT_SYMBOL(__stack_chk_guard);
 188 #endif
 189
 190 struct mips_frame_info {
 191         void            *func;
 192         unsigned long   func_size;
 193         int             frame_size;
 194         int             pc_offset;
 195 };
 196
 197 #define J_TARGET(pc,target)     \
 198                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 199
 200 static inline int is_ra_save_ins(union mips_instruction *ip, int *poff)
 201 {
 202 #ifdef CONFIG_CPU_MICROMIPS
 203         /*
 204          * swsp ra,offset
 205          * swm16 reglist,offset(sp)
 206          * swm32 reglist,offset(sp)
 207          * sw32 ra,offset(sp)
 208          * jradiussp - NOT SUPPORTED
 209          *
 210          * microMIPS is way more fun...
 211          */
 212         if (mm_insn_16bit(ip->halfword[1])) {
 213                 switch (ip->mm16_r5_format.opcode) {
 214                 case mm_swsp16_op:
 215                         if (ip->mm16_r5_format.rt != 31)
 216                                 return 0;
 217
 218                         *poff = ip->mm16_r5_format.simmediate;
 219                         *poff = (*poff << 2) / sizeof(ulong);
 220                         return 1;
 221
 222                 case mm_pool16c_op:
 223                         switch (ip->mm16_m_format.func) {
 224                         case mm_swm16_op:
 225                                 *poff = ip->mm16_m_format.imm;
 226                                 *poff += 1 + ip->mm16_m_format.rlist;
 227                                 *poff = (*poff << 2) / sizeof(ulong);
 228                                 return 1;
 229
 230                         default:
 231                                 return 0;
 232                         }
 233
 234                 default:
 235                         return 0;
 236                 }
 237         }
 238
 239         switch (ip->i_format.opcode) {
 240         case mm_sw32_op:
 241                 if (ip->i_format.rs != 29)
 242                         return 0;
 243                 if (ip->i_format.rt != 31)
 244                         return 0;
 245
 246                 *poff = ip->i_format.simmediate / sizeof(ulong);
 247                 return 1;
 248
 249         case mm_pool32b_op:
 250                 switch (ip->mm_m_format.func) {
 251                 case mm_swm32_func:
 252                         if (ip->mm_m_format.rd < 0x10)
 253                                 return 0;
 254                         if (ip->mm_m_format.base != 29)
 255                                 return 0;
 256
 257                         *poff = ip->mm_m_format.simmediate;
 258                         *poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32);
 259                         *poff /= sizeof(ulong);
 260                         return 1;
 261                 default:
 262                         return 0;
 263                 }
 264
 265         default:
 266                 return 0;
 267         }
 268 #else
 269         /* sw / sd $ra, offset($sp) */
 270         if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 271                 ip->i_format.rs == 29 && ip->i_format.rt == 31) {
 272                 *poff = ip->i_format.simmediate / sizeof(ulong);
 273                 return 1;
 274         }
 275
 276         return 0;
 277 #endif
 278 }
 279
 280 static inline int is_jump_ins(union mips_instruction *ip)
 281 {
 282 #ifdef CONFIG_CPU_MICROMIPS
 283         /*
 284          * jr16,jrc,jalr16,jalr16
 285          * jal
 286          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 287          * jraddiusp - NOT SUPPORTED
 288          *
 289          * microMIPS is kind of more fun...
 290          */
 291         if (mm_insn_16bit(ip->halfword[1])) {
 292                 if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
 293                     (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op))
 294                         return 1;
 295                 return 0;
 296         }
 297
 298         if (ip->j_format.opcode == mm_j32_op)
 299                 return 1;
 300         if (ip->j_format.opcode == mm_jal32_op)
 301                 return 1;
 302         if (ip->r_format.opcode != mm_pool32a_op ||
 303                         ip->r_format.func != mm_pool32axf_op)
 304                 return 0;
 305         return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 306 #else
 307         if (ip->j_format.opcode == j_op)
 308                 return 1;
 309         if (ip->j_format.opcode == jal_op)
 310                 return 1;
 311         if (ip->r_format.opcode != spec_op)
 312                 return 0;
 313         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 314 #endif
 315 }
 316
 317 static inline int is_sp_move_ins(union mips_instruction *ip)
 318 {
 319 #ifdef CONFIG_CPU_MICROMIPS
 320         /*
 321          * addiusp -imm
 322          * addius5 sp,-imm
 323          * addiu32 sp,sp,-imm
 324          * jradiussp - NOT SUPPORTED
 325          *
 326          * microMIPS is not more fun...
 327          */
 328         if (mm_insn_16bit(ip->halfword[1])) {
 329                 return (ip->mm16_r3_format.opcode == mm_pool16d_op &&
 330                         ip->mm16_r3_format.simmediate && mm_addiusp_func) ||
 331                        (ip->mm16_r5_format.opcode == mm_pool16d_op &&
 332                         ip->mm16_r5_format.rt == 29);
 333         }
 334
 335         return ip->mm_i_format.opcode == mm_addiu32_op &&
 336                ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
 337 #else
 338         /* addiu/daddiu sp,sp,-imm */
 339         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 340                 return 0;
 341         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 342                 return 1;
 343 #endif
 344         return 0;
 345 }
 346
 347 static int get_frame_info(struct mips_frame_info *info)
 348 {
 349         bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
 350         union mips_instruction insn, *ip, *ip_end;
 351         const unsigned int max_insns = 128;
 352         unsigned int i;
 353
 354         info->pc_offset = -1;
 355         info->frame_size = 0;
 356
 357         ip = (void *)msk_isa16_mode((ulong)info->func);
 358         if (!ip)
 359                 goto err;
 360
 361         ip_end = (void *)ip + info->func_size;
 362
 363         for (i = 0; i < max_insns && ip < ip_end; i++, ip++) {
 364                 if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
 365                         insn.halfword[0] = 0;
 366                         insn.halfword[1] = ip->halfword[0];
 367                 } else if (is_mmips) {
 368                         insn.halfword[0] = ip->halfword[1];
 369                         insn.halfword[1] = ip->halfword[0];
 370                 } else {
 371                         insn.word = ip->word;
 372                 }
 373
 374                 if (is_jump_ins(&insn))
 375                         break;
 376
 377                 if (!info->frame_size) {
 378                         if (is_sp_move_ins(&insn))
 379                         {
 380 #ifdef CONFIG_CPU_MICROMIPS
 381                                 if (mm_insn_16bit(ip->halfword[0]))
 382                                 {
 383                                         unsigned short tmp;
 384
 385                                         if (ip->halfword[0] & mm_addiusp_func)
 386                                         {
 387                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 388                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 389                                         } else {
 390                                                 tmp = (ip->halfword[0] >> 1);
 391                                                 info->frame_size = -(signed short)(tmp & 0xf);
 392                                         }
 393                                         ip = (void *) &ip->halfword[1];
 394                                         ip--;
 395                                 } else
 396 #endif
 397                                 info->frame_size = - ip->i_format.simmediate;
 398                         }
 399                         continue;
 400                 }
 401                 if (info->pc_offset == -1 &&
 402                     is_ra_save_ins(&insn, &info->pc_offset))
 403                         break;
 404         }
 405         if (info->frame_size && info->pc_offset >= 0) /* nested */
 406                 return 0;
 407         if (info->pc_offset < 0) /* leaf */
 408                 return 1;
 409         /* prologue seems bogus... */
 410 err:
 411         return -1;
 412 }
 413
 414 static struct mips_frame_info schedule_mfi __read_mostly;
 415
 416 #ifdef CONFIG_KALLSYMS
 417 static unsigned long get___schedule_addr(void)
 418 {
 419         return kallsyms_lookup_name("__schedule");
 420 }
 421 #else
 422 static unsigned long get___schedule_addr(void)
 423 {
 424         union mips_instruction *ip = (void *)schedule;
 425         int max_insns = 8;
 426         int i;
 427
 428         for (i = 0; i < max_insns; i++, ip++) {
 429                 if (ip->j_format.opcode == j_op)
 430                         return J_TARGET(ip, ip->j_format.target);
 431         }
 432         return 0;
 433 }
 434 #endif
 435
 436 static int __init frame_info_init(void)
 437 {
 438         unsigned long size = 0;
 439 #ifdef CONFIG_KALLSYMS
 440         unsigned long ofs;
 441 #endif
 442         unsigned long addr;
 443
 444         addr = get___schedule_addr();
 445         if (!addr)
 446                 addr = (unsigned long)schedule;
 447
 448 #ifdef CONFIG_KALLSYMS
 449         kallsyms_lookup_size_offset(addr, &size, &ofs);
 450 #endif
 451         schedule_mfi.func = (void *)addr;
 452         schedule_mfi.func_size = size;
 453
 454         get_frame_info(&schedule_mfi);
 455
 456         /*
 457          * Without schedule() frame info, result given by
 458          * thread_saved_pc() and get_wchan() are not reliable.
 459          */
 460         if (schedule_mfi.pc_offset < 0)
 461                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 462
 463         return 0;
 464 }
 465
 466 arch_initcall(frame_info_init);
 467
 468 /*
 469  * Return saved PC of a blocked thread.
 470  */
 471 unsigned long thread_saved_pc(struct task_struct *tsk)
 472 {
 473         struct thread_struct *t = &tsk->thread;
 474
 475         /* New born processes are a special case */
 476         if (t->reg31 == (unsigned long) ret_from_fork)
 477                 return t->reg31;
 478         if (schedule_mfi.pc_offset < 0)
 479                 return 0;
 480         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 481 }
 482
 483
 484 #ifdef CONFIG_KALLSYMS
 485 /* generic stack unwinding function */
 486 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 487                                               unsigned long *sp,
 488                                               unsigned long pc,
 489                                               unsigned long *ra)
 490 {
 491         unsigned long low, high, irq_stack_high;
 492         struct mips_frame_info info;
 493         unsigned long size, ofs;
 494         struct pt_regs *regs;
 495         int leaf;
 496
 497         if (!stack_page)
 498                 return 0;
 499
 500         /*
 501          * IRQ stacks start at IRQ_STACK_START
 502          * task stacks at THREAD_SIZE - 32
 503          */
 504         low = stack_page;
 505         if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) {
 506                 high = stack_page + IRQ_STACK_START;
 507                 irq_stack_high = high;
 508         } else {
 509                 high = stack_page + THREAD_SIZE - 32;
 510                 irq_stack_high = 0;
 511         }
 512
 513         /*
 514          * If we reached the top of the interrupt stack, start unwinding
 515          * the interrupted task stack.
 516          */
 517         if (unlikely(*sp == irq_stack_high)) {
 518                 unsigned long task_sp = *(unsigned long *)*sp;
 519
 520                 /*
 521                  * Check that the pointer saved in the IRQ stack head points to
 522                  * something within the stack of the current task
 523                  */
 524                 if (!object_is_on_stack((void *)task_sp))
 525                         return 0;
 526
 527                 /*
 528                  * Follow pointer to tasks kernel stack frame where interrupted
 529                  * state was saved.
 530                  */
 531                 regs = (struct pt_regs *)task_sp;
 532                 pc = regs->cp0_epc;
 533                 if (!user_mode(regs) && __kernel_text_address(pc)) {
 534                         *sp = regs->regs[29];
 535                         *ra = regs->regs[31];
 536                         return pc;
 537                 }
 538                 return 0;
 539         }
 540         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 541                 return 0;
 542         /*
 543          * Return ra if an exception occurred at the first instruction
 544          */
 545         if (unlikely(ofs == 0)) {
 546                 pc = *ra;
 547                 *ra = 0;
 548                 return pc;
 549         }
 550
 551         info.func = (void *)(pc - ofs);
 552         info.func_size = ofs;   /* analyze from start to ofs */
 553         leaf = get_frame_info(&info);
 554         if (leaf < 0)
 555                 return 0;
 556
 557         if (*sp < low || *sp + info.frame_size > high)
 558                 return 0;
 559
 560         if (leaf)
 561                 /*
 562                  * For some extreme cases, get_frame_info() can
 563                  * consider wrongly a nested function as a leaf
 564                  * one. In that cases avoid to return always the
 565                  * same value.
 566                  */
 567                 pc = pc != *ra ? *ra : 0;
 568         else
 569                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 570
 571         *sp += info.frame_size;
 572         *ra = 0;
 573         return __kernel_text_address(pc) ? pc : 0;
 574 }
 575 EXPORT_SYMBOL(unwind_stack_by_address);
 576
 577 /* used by show_backtrace() */
 578 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 579                            unsigned long pc, unsigned long *ra)
 580 {
 581         unsigned long stack_page = 0;
 582         int cpu;
 583
 584         for_each_possible_cpu(cpu) {
 585                 if (on_irq_stack(cpu, *sp)) {
 586                         stack_page = (unsigned long)irq_stack[cpu];
 587                         break;
 588                 }
 589         }
 590
 591         if (!stack_page)
 592                 stack_page = (unsigned long)task_stack_page(task);
 593
 594         return unwind_stack_by_address(stack_page, sp, pc, ra);
 595 }
 596 #endif
 597
 598 /*
 599  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 600  */
 601 unsigned long get_wchan(struct task_struct *task)
 602 {
 603         unsigned long pc = 0;
 604 #ifdef CONFIG_KALLSYMS
 605         unsigned long sp;
 606         unsigned long ra = 0;
 607 #endif
 608
 609         if (!task || task == current || task->state == TASK_RUNNING)
 610                 goto out;
 611         if (!task_stack_page(task))
 612                 goto out;
 613
 614         pc = thread_saved_pc(task);
 615
 616 #ifdef CONFIG_KALLSYMS
 617         sp = task->thread.reg29 + schedule_mfi.frame_size;
 618
 619         while (in_sched_functions(pc))
 620                 pc = unwind_stack(task, &sp, pc, &ra);
 621 #endif
 622
 623 out:
 624         return pc;
 625 }
 626
 627 /*
 628  * Don't forget that the stack pointer must be aligned on a 8 bytes
 629  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 630  */
 631 unsigned long arch_align_stack(unsigned long sp)
 632 {
 633         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 634                 sp -= get_random_int() & ~PAGE_MASK;
 635
 636         return sp & ALMASK;
 637 }
 638
 639 static void arch_dump_stack(void *info)
 640 {
 641         struct pt_regs *regs;
 642
 643         regs = get_irq_regs();
 644
 645         if (regs)
 646                 show_regs(regs);
 647
 648         dump_stack();
 649 }
 650
 651 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 652 {
 653         long this_cpu = get_cpu();
 654
 655         if (cpumask_test_cpu(this_cpu, mask) && !exclude_self)
 656                 dump_stack();
 657
 658         smp_call_function_many(mask, arch_dump_stack, NULL, 1);
 659
 660         put_cpu();
 661 }
 662
 663 int mips_get_process_fp_mode(struct task_struct *task)
 664 {
 665         int value = 0;
 666
 667         if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
 668                 value |= PR_FP_MODE_FR;
 669         if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
 670                 value |= PR_FP_MODE_FRE;
 671
 672         return value;
 673 }
 674
 675 static void prepare_for_fp_mode_switch(void *info)
 676 {
 677         struct mm_struct *mm = info;
 678
 679         if (current->mm == mm)
 680                 lose_fpu(1);
 681 }
 682
 683 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 684 {
 685         const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
 686         struct task_struct *t;
 687         int max_users;
 688
 689         /* Check the value is valid */
 690         if (value & ~known_bits)
 691                 return -EOPNOTSUPP;
 692
 693         /* Avoid inadvertently triggering emulation */
 694         if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
 695             !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
 696                 return -EOPNOTSUPP;
 697         if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
 698                 return -EOPNOTSUPP;
 699
 700         /* FR = 0 not supported in MIPS R6 */
 701         if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
 702                 return -EOPNOTSUPP;
 703
 704         /* Proceed with the mode switch */
 705         preempt_disable();
 706
 707         /* Save FP & vector context, then disable FPU & MSA */
 708         if (task->signal == current->signal)
 709                 lose_fpu(1);
 710
 711         /* Prevent any threads from obtaining live FP context */
 712         atomic_set(&task->mm->context.fp_mode_switching, 1);
 713         smp_mb__after_atomic();
 714
 715         /*
 716          * If there are multiple online CPUs then force any which are running
 717          * threads in this process to lose their FPU context, which they can't
 718          * regain until fp_mode_switching is cleared later.
 719          */
 720         if (num_online_cpus() > 1) {
 721                 /* No need to send an IPI for the local CPU */
 722                 max_users = (task->mm == current->mm) ? 1 : 0;
 723
 724                 if (atomic_read(&current->mm->mm_users) > max_users)
 725                         smp_call_function(prepare_for_fp_mode_switch,
 726                                           (void *)current->mm, 1);
 727         }
 728
 729         /*
 730          * There are now no threads of the process with live FP context, so it
 731          * is safe to proceed with the FP mode switch.
 732          */
 733         for_each_thread(task, t) {
 734                 /* Update desired FP register width */
 735                 if (value & PR_FP_MODE_FR) {
 736                         clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 737                 } else {
 738                         set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 739                         clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
 740                 }
 741
 742                 /* Update desired FP single layout */
 743                 if (value & PR_FP_MODE_FRE)
 744                         set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 745                 else
 746                         clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 747         }
 748
 749         /* Allow threads to use FP again */
 750         atomic_set(&task->mm->context.fp_mode_switching, 0);
 751         preempt_enable();
 752
 753         return 0;
 754 }
 755
 756 #if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
 757 void mips_dump_regs32(u32 *uregs, const struct pt_regs *regs)
 758 {
 759         unsigned int i;
 760
 761         for (i = MIPS32_EF_R1; i <= MIPS32_EF_R31; i++) {
 762                 /* k0/k1 are copied as zero. */
 763                 if (i == MIPS32_EF_R26 || i == MIPS32_EF_R27)
 764                         uregs[i] = 0;
 765                 else
 766                         uregs[i] = regs->regs[i - MIPS32_EF_R0];
 767         }
 768
 769         uregs[MIPS32_EF_LO] = regs->lo;
 770         uregs[MIPS32_EF_HI] = regs->hi;
 771         uregs[MIPS32_EF_CP0_EPC] = regs->cp0_epc;
 772         uregs[MIPS32_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 773         uregs[MIPS32_EF_CP0_STATUS] = regs->cp0_status;
 774         uregs[MIPS32_EF_CP0_CAUSE] = regs->cp0_cause;
 775 }
 776 #endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */
 777
 778 #ifdef CONFIG_64BIT
 779 void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs)
 780 {
 781         unsigned int i;
 782
 783         for (i = MIPS64_EF_R1; i <= MIPS64_EF_R31; i++) {
 784                 /* k0/k1 are copied as zero. */
 785                 if (i == MIPS64_EF_R26 || i == MIPS64_EF_R27)
 786                         uregs[i] = 0;
 787                 else
 788                         uregs[i] = regs->regs[i - MIPS64_EF_R0];
 789         }
 790
 791         uregs[MIPS64_EF_LO] = regs->lo;
 792         uregs[MIPS64_EF_HI] = regs->hi;
 793         uregs[MIPS64_EF_CP0_EPC] = regs->cp0_epc;
 794         uregs[MIPS64_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 795         uregs[MIPS64_EF_CP0_STATUS] = regs->cp0_status;
 796         uregs[MIPS64_EF_CP0_CAUSE] = regs->cp0_cause;
 797 }
 798 #endif /* CONFIG_64BIT */