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 <linux/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         /* What the heck is this check doing ? */
  54         if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map))
  55                 play_dead();
  56 }
  57 #endif
  58
  59 asmlinkage void ret_from_fork(void);
  60 asmlinkage void ret_from_kernel_thread(void);
  61
  62 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  63 {
  64         unsigned long status;
  65
  66         /* New thread loses kernel privileges. */
  67         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
  68         status |= KU_USER;
  69         regs->cp0_status = status;
  70         lose_fpu(0);
  71         clear_thread_flag(TIF_MSA_CTX_LIVE);
  72         clear_used_math();
  73         atomic_set(&current->thread.bd_emu_frame, BD_EMUFRAME_NONE);
  74         init_dsp();
  75         regs->cp0_epc = pc;
  76         regs->regs[29] = sp;
  77 }
  78
  79 void exit_thread(struct task_struct *tsk)
  80 {
  81         /*
  82          * User threads may have allocated a delay slot emulation frame.
  83          * If so, clean up that allocation.
  84          */
  85         if (!(current->flags & PF_KTHREAD))
  86                 dsemul_thread_cleanup(tsk);
  87 }
  88
  89 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  90 {
  91         /*
  92          * Save any process state which is live in hardware registers to the
  93          * parent context prior to duplication. This prevents the new child
  94          * state becoming stale if the parent is preempted before copy_thread()
  95          * gets a chance to save the parent's live hardware registers to the
  96          * child context.
  97          */
  98         preempt_disable();
  99
 100         if (is_msa_enabled())
 101                 save_msa(current);
 102         else if (is_fpu_owner())
 103                 _save_fp(current);
 104
 105         save_dsp(current);
 106
 107         preempt_enable();
 108
 109         *dst = *src;
 110         return 0;
 111 }
 112
 113 /*
 114  * Copy architecture-specific thread state
 115  */
 116 int copy_thread(unsigned long clone_flags, unsigned long usp,
 117         unsigned long kthread_arg, struct task_struct *p)
 118 {
 119         struct thread_info *ti = task_thread_info(p);
 120         struct pt_regs *childregs, *regs = current_pt_regs();
 121         unsigned long childksp;
 122         p->set_child_tid = p->clear_child_tid = NULL;
 123
 124         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 125
 126         /* set up new TSS. */
 127         childregs = (struct pt_regs *) childksp - 1;
 128         /*  Put the stack after the struct pt_regs.  */
 129         childksp = (unsigned long) childregs;
 130         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 131         if (unlikely(p->flags & PF_KTHREAD)) {
 132                 /* kernel thread */
 133                 unsigned long status = p->thread.cp0_status;
 134                 memset(childregs, 0, sizeof(struct pt_regs));
 135                 ti->addr_limit = KERNEL_DS;
 136                 p->thread.reg16 = usp; /* fn */
 137                 p->thread.reg17 = kthread_arg;
 138                 p->thread.reg29 = childksp;
 139                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 140 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 141                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 142                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 143 #else
 144                 status |= ST0_EXL;
 145 #endif
 146                 childregs->cp0_status = status;
 147                 return 0;
 148         }
 149
 150         /* user thread */
 151         *childregs = *regs;
 152         childregs->regs[7] = 0; /* Clear error flag */
 153         childregs->regs[2] = 0; /* Child gets zero as return value */
 154         if (usp)
 155                 childregs->regs[29] = usp;
 156         ti->addr_limit = USER_DS;
 157
 158         p->thread.reg29 = (unsigned long) childregs;
 159         p->thread.reg31 = (unsigned long) ret_from_fork;
 160
 161         /*
 162          * New tasks lose permission to use the fpu. This accelerates context
 163          * switching for most programs since they don't use the fpu.
 164          */
 165         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 166
 167         clear_tsk_thread_flag(p, TIF_USEDFPU);
 168         clear_tsk_thread_flag(p, TIF_USEDMSA);
 169         clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
 170
 171 #ifdef CONFIG_MIPS_MT_FPAFF
 172         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 173 #endif /* CONFIG_MIPS_MT_FPAFF */
 174
 175         atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
 176
 177         if (clone_flags & CLONE_SETTLS)
 178                 ti->tp_value = regs->regs[7];
 179
 180         return 0;
 181 }
 182
 183 #ifdef CONFIG_CC_STACKPROTECTOR
 184 #include <linux/stackprotector.h>
 185 unsigned long __stack_chk_guard __read_mostly;
 186 EXPORT_SYMBOL(__stack_chk_guard);
 187 #endif
 188
 189 struct mips_frame_info {
 190         void            *func;
 191         unsigned long   func_size;
 192         int             frame_size;
 193         int             pc_offset;
 194 };
 195
 196 #define J_TARGET(pc,target)     \
 197                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 198
 199 static inline int is_ra_save_ins(union mips_instruction *ip)
 200 {
 201 #ifdef CONFIG_CPU_MICROMIPS
 202         union mips_instruction mmi;
 203
 204         /*
 205          * swsp ra,offset
 206          * swm16 reglist,offset(sp)
 207          * swm32 reglist,offset(sp)
 208          * sw32 ra,offset(sp)
 209          * jradiussp - NOT SUPPORTED
 210          *
 211          * microMIPS is way more fun...
 212          */
 213         if (mm_insn_16bit(ip->halfword[0])) {
 214                 mmi.word = (ip->halfword[0] << 16);
 215                 return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
 216                         mmi.mm16_r5_format.rt == 31) ||
 217                        (mmi.mm16_m_format.opcode == mm_pool16c_op &&
 218                         mmi.mm16_m_format.func == mm_swm16_op);
 219         }
 220         else {
 221                 mmi.halfword[0] = ip->halfword[1];
 222                 mmi.halfword[1] = ip->halfword[0];
 223                 return (mmi.mm_m_format.opcode == mm_pool32b_op &&
 224                         mmi.mm_m_format.rd > 9 &&
 225                         mmi.mm_m_format.base == 29 &&
 226                         mmi.mm_m_format.func == mm_swm32_func) ||
 227                        (mmi.i_format.opcode == mm_sw32_op &&
 228                         mmi.i_format.rs == 29 &&
 229                         mmi.i_format.rt == 31);
 230         }
 231 #else
 232         /* sw / sd $ra, offset($sp) */
 233         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 234                 ip->i_format.rs == 29 &&
 235                 ip->i_format.rt == 31;
 236 #endif
 237 }
 238
 239 static inline int is_jump_ins(union mips_instruction *ip)
 240 {
 241 #ifdef CONFIG_CPU_MICROMIPS
 242         /*
 243          * jr16,jrc,jalr16,jalr16
 244          * jal
 245          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 246          * jraddiusp - NOT SUPPORTED
 247          *
 248          * microMIPS is kind of more fun...
 249          */
 250         union mips_instruction mmi;
 251
 252         mmi.word = (ip->halfword[0] << 16);
 253
 254         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
 255             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
 256             ip->j_format.opcode == mm_jal32_op)
 257                 return 1;
 258         if (ip->r_format.opcode != mm_pool32a_op ||
 259                         ip->r_format.func != mm_pool32axf_op)
 260                 return 0;
 261         return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 262 #else
 263         if (ip->j_format.opcode == j_op)
 264                 return 1;
 265         if (ip->j_format.opcode == jal_op)
 266                 return 1;
 267         if (ip->r_format.opcode != spec_op)
 268                 return 0;
 269         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 270 #endif
 271 }
 272
 273 static inline int is_sp_move_ins(union mips_instruction *ip)
 274 {
 275 #ifdef CONFIG_CPU_MICROMIPS
 276         /*
 277          * addiusp -imm
 278          * addius5 sp,-imm
 279          * addiu32 sp,sp,-imm
 280          * jradiussp - NOT SUPPORTED
 281          *
 282          * microMIPS is not more fun...
 283          */
 284         if (mm_insn_16bit(ip->halfword[0])) {
 285                 union mips_instruction mmi;
 286
 287                 mmi.word = (ip->halfword[0] << 16);
 288                 return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
 289                         mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
 290                        (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
 291                         mmi.mm16_r5_format.rt == 29);
 292         }
 293         return ip->mm_i_format.opcode == mm_addiu32_op &&
 294                ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
 295 #else
 296         /* addiu/daddiu sp,sp,-imm */
 297         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 298                 return 0;
 299         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 300                 return 1;
 301 #endif
 302         return 0;
 303 }
 304
 305 static int get_frame_info(struct mips_frame_info *info)
 306 {
 307 #ifdef CONFIG_CPU_MICROMIPS
 308         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
 309 #else
 310         union mips_instruction *ip = info->func;
 311 #endif
 312         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 313         unsigned i;
 314
 315         info->pc_offset = -1;
 316         info->frame_size = 0;
 317
 318         if (!ip)
 319                 goto err;
 320
 321         if (max_insns == 0)
 322                 max_insns = 128U;       /* unknown function size */
 323         max_insns = min(128U, max_insns);
 324
 325         for (i = 0; i < max_insns; i++, ip++) {
 326
 327                 if (is_jump_ins(ip))
 328                         break;
 329                 if (!info->frame_size) {
 330                         if (is_sp_move_ins(ip))
 331                         {
 332 #ifdef CONFIG_CPU_MICROMIPS
 333                                 if (mm_insn_16bit(ip->halfword[0]))
 334                                 {
 335                                         unsigned short tmp;
 336
 337                                         if (ip->halfword[0] & mm_addiusp_func)
 338                                         {
 339                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 340                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 341                                         } else {
 342                                                 tmp = (ip->halfword[0] >> 1);
 343                                                 info->frame_size = -(signed short)(tmp & 0xf);
 344                                         }
 345                                         ip = (void *) &ip->halfword[1];
 346                                         ip--;
 347                                 } else
 348 #endif
 349                                 info->frame_size = - ip->i_format.simmediate;
 350                         }
 351                         continue;
 352                 }
 353                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
 354                         info->pc_offset =
 355                                 ip->i_format.simmediate / sizeof(long);
 356                         break;
 357                 }
 358         }
 359         if (info->frame_size && info->pc_offset >= 0) /* nested */
 360                 return 0;
 361         if (info->pc_offset < 0) /* leaf */
 362                 return 1;
 363         /* prologue seems bogus... */
 364 err:
 365         return -1;
 366 }
 367
 368 static struct mips_frame_info schedule_mfi __read_mostly;
 369
 370 #ifdef CONFIG_KALLSYMS
 371 static unsigned long get___schedule_addr(void)
 372 {
 373         return kallsyms_lookup_name("__schedule");
 374 }
 375 #else
 376 static unsigned long get___schedule_addr(void)
 377 {
 378         union mips_instruction *ip = (void *)schedule;
 379         int max_insns = 8;
 380         int i;
 381
 382         for (i = 0; i < max_insns; i++, ip++) {
 383                 if (ip->j_format.opcode == j_op)
 384                         return J_TARGET(ip, ip->j_format.target);
 385         }
 386         return 0;
 387 }
 388 #endif
 389
 390 static int __init frame_info_init(void)
 391 {
 392         unsigned long size = 0;
 393 #ifdef CONFIG_KALLSYMS
 394         unsigned long ofs;
 395 #endif
 396         unsigned long addr;
 397
 398         addr = get___schedule_addr();
 399         if (!addr)
 400                 addr = (unsigned long)schedule;
 401
 402 #ifdef CONFIG_KALLSYMS
 403         kallsyms_lookup_size_offset(addr, &size, &ofs);
 404 #endif
 405         schedule_mfi.func = (void *)addr;
 406         schedule_mfi.func_size = size;
 407
 408         get_frame_info(&schedule_mfi);
 409
 410         /*
 411          * Without schedule() frame info, result given by
 412          * thread_saved_pc() and get_wchan() are not reliable.
 413          */
 414         if (schedule_mfi.pc_offset < 0)
 415                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 416
 417         return 0;
 418 }
 419
 420 arch_initcall(frame_info_init);
 421
 422 /*
 423  * Return saved PC of a blocked thread.
 424  */
 425 unsigned long thread_saved_pc(struct task_struct *tsk)
 426 {
 427         struct thread_struct *t = &tsk->thread;
 428
 429         /* New born processes are a special case */
 430         if (t->reg31 == (unsigned long) ret_from_fork)
 431                 return t->reg31;
 432         if (schedule_mfi.pc_offset < 0)
 433                 return 0;
 434         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 435 }
 436
 437
 438 #ifdef CONFIG_KALLSYMS
 439 /* generic stack unwinding function */
 440 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 441                                               unsigned long *sp,
 442                                               unsigned long pc,
 443                                               unsigned long *ra)
 444 {
 445         struct mips_frame_info info;
 446         unsigned long size, ofs;
 447         int leaf;
 448         extern void ret_from_irq(void);
 449         extern void ret_from_exception(void);
 450
 451         if (!stack_page)
 452                 return 0;
 453
 454         /*
 455          * If we reached the bottom of interrupt context,
 456          * return saved pc in pt_regs.
 457          */
 458         if (pc == (unsigned long)ret_from_irq ||
 459             pc == (unsigned long)ret_from_exception) {
 460                 struct pt_regs *regs;
 461                 if (*sp >= stack_page &&
 462                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
 463                         regs = (struct pt_regs *)*sp;
 464                         pc = regs->cp0_epc;
 465                         if (!user_mode(regs) && __kernel_text_address(pc)) {
 466                                 *sp = regs->regs[29];
 467                                 *ra = regs->regs[31];
 468                                 return pc;
 469                         }
 470                 }
 471                 return 0;
 472         }
 473         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 474                 return 0;
 475         /*
 476          * Return ra if an exception occurred at the first instruction
 477          */
 478         if (unlikely(ofs == 0)) {
 479                 pc = *ra;
 480                 *ra = 0;
 481                 return pc;
 482         }
 483
 484         info.func = (void *)(pc - ofs);
 485         info.func_size = ofs;   /* analyze from start to ofs */
 486         leaf = get_frame_info(&info);
 487         if (leaf < 0)
 488                 return 0;
 489
 490         if (*sp < stack_page ||
 491             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
 492                 return 0;
 493
 494         if (leaf)
 495                 /*
 496                  * For some extreme cases, get_frame_info() can
 497                  * consider wrongly a nested function as a leaf
 498                  * one. In that cases avoid to return always the
 499                  * same value.
 500                  */
 501                 pc = pc != *ra ? *ra : 0;
 502         else
 503                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 504
 505         *sp += info.frame_size;
 506         *ra = 0;
 507         return __kernel_text_address(pc) ? pc : 0;
 508 }
 509 EXPORT_SYMBOL(unwind_stack_by_address);
 510
 511 /* used by show_backtrace() */
 512 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 513                            unsigned long pc, unsigned long *ra)
 514 {
 515         unsigned long stack_page = 0;
 516         int cpu;
 517
 518         for_each_possible_cpu(cpu) {
 519                 if (on_irq_stack(cpu, *sp)) {
 520                         stack_page = (unsigned long)irq_stack[cpu];
 521                         break;
 522                 }
 523         }
 524
 525         if (!stack_page)
 526                 stack_page = (unsigned long)task_stack_page(task);
 527
 528         return unwind_stack_by_address(stack_page, sp, pc, ra);
 529 }
 530 #endif
 531
 532 /*
 533  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 534  */
 535 unsigned long get_wchan(struct task_struct *task)
 536 {
 537         unsigned long pc = 0;
 538 #ifdef CONFIG_KALLSYMS
 539         unsigned long sp;
 540         unsigned long ra = 0;
 541 #endif
 542
 543         if (!task || task == current || task->state == TASK_RUNNING)
 544                 goto out;
 545         if (!task_stack_page(task))
 546                 goto out;
 547
 548         pc = thread_saved_pc(task);
 549
 550 #ifdef CONFIG_KALLSYMS
 551         sp = task->thread.reg29 + schedule_mfi.frame_size;
 552
 553         while (in_sched_functions(pc))
 554                 pc = unwind_stack(task, &sp, pc, &ra);
 555 #endif
 556
 557 out:
 558         return pc;
 559 }
 560
 561 /*
 562  * Don't forget that the stack pointer must be aligned on a 8 bytes
 563  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 564  */
 565 unsigned long arch_align_stack(unsigned long sp)
 566 {
 567         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 568                 sp -= get_random_int() & ~PAGE_MASK;
 569
 570         return sp & ALMASK;
 571 }
 572
 573 static void arch_dump_stack(void *info)
 574 {
 575         struct pt_regs *regs;
 576
 577         regs = get_irq_regs();
 578
 579         if (regs)
 580                 show_regs(regs);
 581
 582         dump_stack();
 583 }
 584
 585 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 586 {
 587         long this_cpu = get_cpu();
 588
 589         if (cpumask_test_cpu(this_cpu, mask) && !exclude_self)
 590                 dump_stack();
 591
 592         smp_call_function_many(mask, arch_dump_stack, NULL, 1);
 593
 594         put_cpu();
 595 }
 596
 597 int mips_get_process_fp_mode(struct task_struct *task)
 598 {
 599         int value = 0;
 600
 601         if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
 602                 value |= PR_FP_MODE_FR;
 603         if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
 604                 value |= PR_FP_MODE_FRE;
 605
 606         return value;
 607 }
 608
 609 static void prepare_for_fp_mode_switch(void *info)
 610 {
 611         struct mm_struct *mm = info;
 612
 613         if (current->mm == mm)
 614                 lose_fpu(1);
 615 }
 616
 617 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 618 {
 619         const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
 620         struct task_struct *t;
 621         int max_users;
 622
 623         /* Check the value is valid */
 624         if (value & ~known_bits)
 625                 return -EOPNOTSUPP;
 626
 627         /* Avoid inadvertently triggering emulation */
 628         if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
 629             !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
 630                 return -EOPNOTSUPP;
 631         if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
 632                 return -EOPNOTSUPP;
 633
 634         /* FR = 0 not supported in MIPS R6 */
 635         if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
 636                 return -EOPNOTSUPP;
 637
 638         /* Proceed with the mode switch */
 639         preempt_disable();
 640
 641         /* Save FP & vector context, then disable FPU & MSA */
 642         if (task->signal == current->signal)
 643                 lose_fpu(1);
 644
 645         /* Prevent any threads from obtaining live FP context */
 646         atomic_set(&task->mm->context.fp_mode_switching, 1);
 647         smp_mb__after_atomic();
 648
 649         /*
 650          * If there are multiple online CPUs then force any which are running
 651          * threads in this process to lose their FPU context, which they can't
 652          * regain until fp_mode_switching is cleared later.
 653          */
 654         if (num_online_cpus() > 1) {
 655                 /* No need to send an IPI for the local CPU */
 656                 max_users = (task->mm == current->mm) ? 1 : 0;
 657
 658                 if (atomic_read(&current->mm->mm_users) > max_users)
 659                         smp_call_function(prepare_for_fp_mode_switch,
 660                                           (void *)current->mm, 1);
 661         }
 662
 663         /*
 664          * There are now no threads of the process with live FP context, so it
 665          * is safe to proceed with the FP mode switch.
 666          */
 667         for_each_thread(task, t) {
 668                 /* Update desired FP register width */
 669                 if (value & PR_FP_MODE_FR) {
 670                         clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 671                 } else {
 672                         set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 673                         clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
 674                 }
 675
 676                 /* Update desired FP single layout */
 677                 if (value & PR_FP_MODE_FRE)
 678                         set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 679                 else
 680                         clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 681         }
 682
 683         /* Allow threads to use FP again */
 684         atomic_set(&task->mm->context.fp_mode_switching, 0);
 685         preempt_enable();
 686
 687         return 0;
 688 }