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/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(&current->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                 ti->addr_limit = KERNEL_DS;
 128                 p->thread.reg16 = usp; /* fn */
 129                 p->thread.reg17 = kthread_arg;
 130                 p->thread.reg29 = childksp;
 131                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 132 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 133                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 134                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 135 #else
 136                 status |= ST0_EXL;
 137 #endif
 138                 childregs->cp0_status = status;
 139                 return 0;
 140         }
 141
 142         /* user thread */
 143         *childregs = *regs;
 144         childregs->regs[7] = 0; /* Clear error flag */
 145         childregs->regs[2] = 0; /* Child gets zero as return value */
 146         if (usp)
 147                 childregs->regs[29] = usp;
 148         ti->addr_limit = USER_DS;
 149
 150         p->thread.reg29 = (unsigned long) childregs;
 151         p->thread.reg31 = (unsigned long) ret_from_fork;
 152
 153         /*
 154          * New tasks lose permission to use the fpu. This accelerates context
 155          * switching for most programs since they don't use the fpu.
 156          */
 157         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 158
 159         clear_tsk_thread_flag(p, TIF_USEDFPU);
 160         clear_tsk_thread_flag(p, TIF_USEDMSA);
 161         clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
 162
 163 #ifdef CONFIG_MIPS_MT_FPAFF
 164         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 165 #endif /* CONFIG_MIPS_MT_FPAFF */
 166
 167 #ifdef CONFIG_MIPS_FP_SUPPORT
 168         atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
 169 #endif
 170
 171         if (clone_flags & CLONE_SETTLS)
 172                 ti->tp_value = tls;
 173
 174         return 0;
 175 }
 176
 177 #ifdef CONFIG_STACKPROTECTOR
 178 #include <linux/stackprotector.h>
 179 unsigned long __stack_chk_guard __read_mostly;
 180 EXPORT_SYMBOL(__stack_chk_guard);
 181 #endif
 182
 183 struct mips_frame_info {
 184         void            *func;
 185         unsigned long   func_size;
 186         int             frame_size;
 187         int             pc_offset;
 188 };
 189
 190 #define J_TARGET(pc,target)     \
 191                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 192
 193 static inline int is_jr_ra_ins(union mips_instruction *ip)
 194 {
 195 #ifdef CONFIG_CPU_MICROMIPS
 196         /*
 197          * jr16 ra
 198          * jr ra
 199          */
 200         if (mm_insn_16bit(ip->word >> 16)) {
 201                 if (ip->mm16_r5_format.opcode == mm_pool16c_op &&
 202                     ip->mm16_r5_format.rt == mm_jr16_op &&
 203                     ip->mm16_r5_format.imm == 31)
 204                         return 1;
 205                 return 0;
 206         }
 207
 208         if (ip->r_format.opcode == mm_pool32a_op &&
 209             ip->r_format.func == mm_pool32axf_op &&
 210             ((ip->u_format.uimmediate >> 6) & GENMASK(9, 0)) == mm_jalr_op &&
 211             ip->r_format.rt == 31)
 212                 return 1;
 213         return 0;
 214 #else
 215         if (ip->r_format.opcode == spec_op &&
 216             ip->r_format.func == jr_op &&
 217             ip->r_format.rs == 31)
 218                 return 1;
 219         return 0;
 220 #endif
 221 }
 222
 223 static inline int is_ra_save_ins(union mips_instruction *ip, int *poff)
 224 {
 225 #ifdef CONFIG_CPU_MICROMIPS
 226         /*
 227          * swsp ra,offset
 228          * swm16 reglist,offset(sp)
 229          * swm32 reglist,offset(sp)
 230          * sw32 ra,offset(sp)
 231          * jradiussp - NOT SUPPORTED
 232          *
 233          * microMIPS is way more fun...
 234          */
 235         if (mm_insn_16bit(ip->word >> 16)) {
 236                 switch (ip->mm16_r5_format.opcode) {
 237                 case mm_swsp16_op:
 238                         if (ip->mm16_r5_format.rt != 31)
 239                                 return 0;
 240
 241                         *poff = ip->mm16_r5_format.imm;
 242                         *poff = (*poff << 2) / sizeof(ulong);
 243                         return 1;
 244
 245                 case mm_pool16c_op:
 246                         switch (ip->mm16_m_format.func) {
 247                         case mm_swm16_op:
 248                                 *poff = ip->mm16_m_format.imm;
 249                                 *poff += 1 + ip->mm16_m_format.rlist;
 250                                 *poff = (*poff << 2) / sizeof(ulong);
 251                                 return 1;
 252
 253                         default:
 254                                 return 0;
 255                         }
 256
 257                 default:
 258                         return 0;
 259                 }
 260         }
 261
 262         switch (ip->i_format.opcode) {
 263         case mm_sw32_op:
 264                 if (ip->i_format.rs != 29)
 265                         return 0;
 266                 if (ip->i_format.rt != 31)
 267                         return 0;
 268
 269                 *poff = ip->i_format.simmediate / sizeof(ulong);
 270                 return 1;
 271
 272         case mm_pool32b_op:
 273                 switch (ip->mm_m_format.func) {
 274                 case mm_swm32_func:
 275                         if (ip->mm_m_format.rd < 0x10)
 276                                 return 0;
 277                         if (ip->mm_m_format.base != 29)
 278                                 return 0;
 279
 280                         *poff = ip->mm_m_format.simmediate;
 281                         *poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32);
 282                         *poff /= sizeof(ulong);
 283                         return 1;
 284                 default:
 285                         return 0;
 286                 }
 287
 288         default:
 289                 return 0;
 290         }
 291 #else
 292         /* sw / sd $ra, offset($sp) */
 293         if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 294                 ip->i_format.rs == 29 && ip->i_format.rt == 31) {
 295                 *poff = ip->i_format.simmediate / sizeof(ulong);
 296                 return 1;
 297         }
 298 #ifdef CONFIG_CPU_LOONGSON64
 299         if ((ip->loongson3_lswc2_format.opcode == swc2_op) &&
 300                       (ip->loongson3_lswc2_format.ls == 1) &&
 301                       (ip->loongson3_lswc2_format.fr == 0) &&
 302                       (ip->loongson3_lswc2_format.base == 29)) {
 303                 if (ip->loongson3_lswc2_format.rt == 31) {
 304                         *poff = ip->loongson3_lswc2_format.offset << 1;
 305                         return 1;
 306                 }
 307                 if (ip->loongson3_lswc2_format.rq == 31) {
 308                         *poff = (ip->loongson3_lswc2_format.offset << 1) + 1;
 309                         return 1;
 310                 }
 311         }
 312 #endif
 313         return 0;
 314 #endif
 315 }
 316
 317 static inline int is_jump_ins(union mips_instruction *ip)
 318 {
 319 #ifdef CONFIG_CPU_MICROMIPS
 320         /*
 321          * jr16,jrc,jalr16,jalr16
 322          * jal
 323          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 324          * jraddiusp - NOT SUPPORTED
 325          *
 326          * microMIPS is kind of more fun...
 327          */
 328         if (mm_insn_16bit(ip->word >> 16)) {
 329                 if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
 330                     (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op))
 331                         return 1;
 332                 return 0;
 333         }
 334
 335         if (ip->j_format.opcode == mm_j32_op)
 336                 return 1;
 337         if (ip->j_format.opcode == mm_jal32_op)
 338                 return 1;
 339         if (ip->r_format.opcode != mm_pool32a_op ||
 340                         ip->r_format.func != mm_pool32axf_op)
 341                 return 0;
 342         return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 343 #else
 344         if (ip->j_format.opcode == j_op)
 345                 return 1;
 346         if (ip->j_format.opcode == jal_op)
 347                 return 1;
 348         if (ip->r_format.opcode != spec_op)
 349                 return 0;
 350         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 351 #endif
 352 }
 353
 354 static inline int is_sp_move_ins(union mips_instruction *ip, int *frame_size)
 355 {
 356 #ifdef CONFIG_CPU_MICROMIPS
 357         unsigned short tmp;
 358
 359         /*
 360          * addiusp -imm
 361          * addius5 sp,-imm
 362          * addiu32 sp,sp,-imm
 363          * jradiussp - NOT SUPPORTED
 364          *
 365          * microMIPS is not more fun...
 366          */
 367         if (mm_insn_16bit(ip->word >> 16)) {
 368                 if (ip->mm16_r3_format.opcode == mm_pool16d_op &&
 369                     ip->mm16_r3_format.simmediate & mm_addiusp_func) {
 370                         tmp = ip->mm_b0_format.simmediate >> 1;
 371                         tmp = ((tmp & 0x1ff) ^ 0x100) - 0x100;
 372                         if ((tmp + 2) < 4) /* 0x0,0x1,0x1fe,0x1ff are special */
 373                                 tmp ^= 0x100;
 374                         *frame_size = -(signed short)(tmp << 2);
 375                         return 1;
 376                 }
 377                 if (ip->mm16_r5_format.opcode == mm_pool16d_op &&
 378                     ip->mm16_r5_format.rt == 29) {
 379                         tmp = ip->mm16_r5_format.imm >> 1;
 380                         *frame_size = -(signed short)(tmp & 0xf);
 381                         return 1;
 382                 }
 383                 return 0;
 384         }
 385
 386         if (ip->mm_i_format.opcode == mm_addiu32_op &&
 387             ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29) {
 388                 *frame_size = -ip->i_format.simmediate;
 389                 return 1;
 390         }
 391 #else
 392         /* addiu/daddiu sp,sp,-imm */
 393         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 394                 return 0;
 395
 396         if (ip->i_format.opcode == addiu_op ||
 397             ip->i_format.opcode == daddiu_op) {
 398                 *frame_size = -ip->i_format.simmediate;
 399                 return 1;
 400         }
 401 #endif
 402         return 0;
 403 }
 404
 405 static int get_frame_info(struct mips_frame_info *info)
 406 {
 407         bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
 408         union mips_instruction insn, *ip, *ip_end;
 409         unsigned int last_insn_size = 0;
 410         bool saw_jump = false;
 411
 412         info->pc_offset = -1;
 413         info->frame_size = 0;
 414
 415         ip = (void *)msk_isa16_mode((ulong)info->func);
 416         if (!ip)
 417                 goto err;
 418
 419         ip_end = (void *)ip + (info->func_size ? info->func_size : 512);
 420
 421         while (ip < ip_end) {
 422                 ip = (void *)ip + last_insn_size;
 423
 424                 if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
 425                         insn.word = ip->halfword[0] << 16;
 426                         last_insn_size = 2;
 427                 } else if (is_mmips) {
 428                         insn.word = ip->halfword[0] << 16 | ip->halfword[1];
 429                         last_insn_size = 4;
 430                 } else {
 431                         insn.word = ip->word;
 432                         last_insn_size = 4;
 433                 }
 434
 435                 if (is_jr_ra_ins(ip)) {
 436                         break;
 437                 } else if (!info->frame_size) {
 438                         is_sp_move_ins(&insn, &info->frame_size);
 439                         continue;
 440                 } else if (!saw_jump && is_jump_ins(ip)) {
 441                         /*
 442                          * If we see a jump instruction, we are finished
 443                          * with the frame save.
 444                          *
 445                          * Some functions can have a shortcut return at
 446                          * the beginning of the function, so don't start
 447                          * looking for jump instruction until we see the
 448                          * frame setup.
 449                          *
 450                          * The RA save instruction can get put into the
 451                          * delay slot of the jump instruction, so look
 452                          * at the next instruction, too.
 453                          */
 454                         saw_jump = true;
 455                         continue;
 456                 }
 457                 if (info->pc_offset == -1 &&
 458                     is_ra_save_ins(&insn, &info->pc_offset))
 459                         break;
 460                 if (saw_jump)
 461                         break;
 462         }
 463         if (info->frame_size && info->pc_offset >= 0) /* nested */
 464                 return 0;
 465         if (info->pc_offset < 0) /* leaf */
 466                 return 1;
 467         /* prologue seems bogus... */
 468 err:
 469         return -1;
 470 }
 471
 472 static struct mips_frame_info schedule_mfi __read_mostly;
 473
 474 #ifdef CONFIG_KALLSYMS
 475 static unsigned long get___schedule_addr(void)
 476 {
 477         return kallsyms_lookup_name("__schedule");
 478 }
 479 #else
 480 static unsigned long get___schedule_addr(void)
 481 {
 482         union mips_instruction *ip = (void *)schedule;
 483         int max_insns = 8;
 484         int i;
 485
 486         for (i = 0; i < max_insns; i++, ip++) {
 487                 if (ip->j_format.opcode == j_op)
 488                         return J_TARGET(ip, ip->j_format.target);
 489         }
 490         return 0;
 491 }
 492 #endif
 493
 494 static int __init frame_info_init(void)
 495 {
 496         unsigned long size = 0;
 497 #ifdef CONFIG_KALLSYMS
 498         unsigned long ofs;
 499 #endif
 500         unsigned long addr;
 501
 502         addr = get___schedule_addr();
 503         if (!addr)
 504                 addr = (unsigned long)schedule;
 505
 506 #ifdef CONFIG_KALLSYMS
 507         kallsyms_lookup_size_offset(addr, &size, &ofs);
 508 #endif
 509         schedule_mfi.func = (void *)addr;
 510         schedule_mfi.func_size = size;
 511
 512         get_frame_info(&schedule_mfi);
 513
 514         /*
 515          * Without schedule() frame info, result given by
 516          * thread_saved_pc() and get_wchan() are not reliable.
 517          */
 518         if (schedule_mfi.pc_offset < 0)
 519                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 520
 521         return 0;
 522 }
 523
 524 arch_initcall(frame_info_init);
 525
 526 /*
 527  * Return saved PC of a blocked thread.
 528  */
 529 static unsigned long thread_saved_pc(struct task_struct *tsk)
 530 {
 531         struct thread_struct *t = &tsk->thread;
 532
 533         /* New born processes are a special case */
 534         if (t->reg31 == (unsigned long) ret_from_fork)
 535                 return t->reg31;
 536         if (schedule_mfi.pc_offset < 0)
 537                 return 0;
 538         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 539 }
 540
 541
 542 #ifdef CONFIG_KALLSYMS
 543 /* generic stack unwinding function */
 544 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 545                                               unsigned long *sp,
 546                                               unsigned long pc,
 547                                               unsigned long *ra)
 548 {
 549         unsigned long low, high, irq_stack_high;
 550         struct mips_frame_info info;
 551         unsigned long size, ofs;
 552         struct pt_regs *regs;
 553         int leaf;
 554
 555         if (!stack_page)
 556                 return 0;
 557
 558         /*
 559          * IRQ stacks start at IRQ_STACK_START
 560          * task stacks at THREAD_SIZE - 32
 561          */
 562         low = stack_page;
 563         if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) {
 564                 high = stack_page + IRQ_STACK_START;
 565                 irq_stack_high = high;
 566         } else {
 567                 high = stack_page + THREAD_SIZE - 32;
 568                 irq_stack_high = 0;
 569         }
 570
 571         /*
 572          * If we reached the top of the interrupt stack, start unwinding
 573          * the interrupted task stack.
 574          */
 575         if (unlikely(*sp == irq_stack_high)) {
 576                 unsigned long task_sp = *(unsigned long *)*sp;
 577
 578                 /*
 579                  * Check that the pointer saved in the IRQ stack head points to
 580                  * something within the stack of the current task
 581                  */
 582                 if (!object_is_on_stack((void *)task_sp))
 583                         return 0;
 584
 585                 /*
 586                  * Follow pointer to tasks kernel stack frame where interrupted
 587                  * state was saved.
 588                  */
 589                 regs = (struct pt_regs *)task_sp;
 590                 pc = regs->cp0_epc;
 591                 if (!user_mode(regs) && __kernel_text_address(pc)) {
 592                         *sp = regs->regs[29];
 593                         *ra = regs->regs[31];
 594                         return pc;
 595                 }
 596                 return 0;
 597         }
 598         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 599                 return 0;
 600         /*
 601          * Return ra if an exception occurred at the first instruction
 602          */
 603         if (unlikely(ofs == 0)) {
 604                 pc = *ra;
 605                 *ra = 0;
 606                 return pc;
 607         }
 608
 609         info.func = (void *)(pc - ofs);
 610         info.func_size = ofs;   /* analyze from start to ofs */
 611         leaf = get_frame_info(&info);
 612         if (leaf < 0)
 613                 return 0;
 614
 615         if (*sp < low || *sp + info.frame_size > high)
 616                 return 0;
 617
 618         if (leaf)
 619                 /*
 620                  * For some extreme cases, get_frame_info() can
 621                  * consider wrongly a nested function as a leaf
 622                  * one. In that cases avoid to return always the
 623                  * same value.
 624                  */
 625                 pc = pc != *ra ? *ra : 0;
 626         else
 627                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 628
 629         *sp += info.frame_size;
 630         *ra = 0;
 631         return __kernel_text_address(pc) ? pc : 0;
 632 }
 633 EXPORT_SYMBOL(unwind_stack_by_address);
 634
 635 /* used by show_backtrace() */
 636 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 637                            unsigned long pc, unsigned long *ra)
 638 {
 639         unsigned long stack_page = 0;
 640         int cpu;
 641
 642         for_each_possible_cpu(cpu) {
 643                 if (on_irq_stack(cpu, *sp)) {
 644                         stack_page = (unsigned long)irq_stack[cpu];
 645                         break;
 646                 }
 647         }
 648
 649         if (!stack_page)
 650                 stack_page = (unsigned long)task_stack_page(task);
 651
 652         return unwind_stack_by_address(stack_page, sp, pc, ra);
 653 }
 654 #endif
 655
 656 /*
 657  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 658  */
 659 unsigned long get_wchan(struct task_struct *task)
 660 {
 661         unsigned long pc = 0;
 662 #ifdef CONFIG_KALLSYMS
 663         unsigned long sp;
 664         unsigned long ra = 0;
 665 #endif
 666
 667         if (!task || task == current || task->state == TASK_RUNNING)
 668                 goto out;
 669         if (!task_stack_page(task))
 670                 goto out;
 671
 672         pc = thread_saved_pc(task);
 673
 674 #ifdef CONFIG_KALLSYMS
 675         sp = task->thread.reg29 + schedule_mfi.frame_size;
 676
 677         while (in_sched_functions(pc))
 678                 pc = unwind_stack(task, &sp, pc, &ra);
 679 #endif
 680
 681 out:
 682         return pc;
 683 }
 684
 685 unsigned long mips_stack_top(void)
 686 {
 687         unsigned long top = TASK_SIZE & PAGE_MASK;
 688
 689         if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
 690                 /* One page for branch delay slot "emulation" */
 691                 top -= PAGE_SIZE;
 692         }
 693
 694         /* Space for the VDSO, data page & GIC user page */
 695         top -= PAGE_ALIGN(current->thread.abi->vdso->size);
 696         top -= PAGE_SIZE;
 697         top -= mips_gic_present() ? PAGE_SIZE : 0;
 698
 699         /* Space for cache colour alignment */
 700         if (cpu_has_dc_aliases)
 701                 top -= shm_align_mask + 1;
 702
 703         /* Space to randomize the VDSO base */
 704         if (current->flags & PF_RANDOMIZE)
 705                 top -= VDSO_RANDOMIZE_SIZE;
 706
 707         return top;
 708 }
 709
 710 /*
 711  * Don't forget that the stack pointer must be aligned on a 8 bytes
 712  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 713  */
 714 unsigned long arch_align_stack(unsigned long sp)
 715 {
 716         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 717                 sp -= get_random_int() & ~PAGE_MASK;
 718
 719         return sp & ALMASK;
 720 }
 721
 722 static struct cpumask backtrace_csd_busy;
 723
 724 static void handle_backtrace(void *info)
 725 {
 726         nmi_cpu_backtrace(get_irq_regs());
 727         cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
 728 }
 729
 730 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd) =
 731         CSD_INIT(handle_backtrace, NULL);
 732
 733 static void raise_backtrace(cpumask_t *mask)
 734 {
 735         call_single_data_t *csd;
 736         int cpu;
 737
 738         for_each_cpu(cpu, mask) {
 739                 /*
 740                  * If we previously sent an IPI to the target CPU & it hasn't
 741                  * cleared its bit in the busy cpumask then it didn't handle
 742                  * our previous IPI & it's not safe for us to reuse the
 743                  * call_single_data_t.
 744                  */
 745                 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
 746                         pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
 747                                 cpu);
 748                         continue;
 749                 }
 750
 751                 csd = &per_cpu(backtrace_csd, cpu);
 752                 smp_call_function_single_async(cpu, csd);
 753         }
 754 }
 755
 756 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 757 {
 758         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
 759 }
 760
 761 int mips_get_process_fp_mode(struct task_struct *task)
 762 {
 763         int value = 0;
 764
 765         if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
 766                 value |= PR_FP_MODE_FR;
 767         if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
 768                 value |= PR_FP_MODE_FRE;
 769
 770         return value;
 771 }
 772
 773 static long prepare_for_fp_mode_switch(void *unused)
 774 {
 775         /*
 776          * This is icky, but we use this to simply ensure that all CPUs have
 777          * context switched, regardless of whether they were previously running
 778          * kernel or user code. This ensures that no CPU that a mode-switching
 779          * program may execute on keeps its FPU enabled (& in the old mode)
 780          * throughout the mode switch.
 781          */
 782         return 0;
 783 }
 784
 785 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 786 {
 787         const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
 788         struct task_struct *t;
 789         struct cpumask process_cpus;
 790         int cpu;
 791
 792         /* If nothing to change, return right away, successfully.  */
 793         if (value == mips_get_process_fp_mode(task))
 794                 return 0;
 795
 796         /* Only accept a mode change if 64-bit FP enabled for o32.  */
 797         if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
 798                 return -EOPNOTSUPP;
 799
 800         /* And only for o32 tasks.  */
 801         if (IS_ENABLED(CONFIG_64BIT) && !test_thread_flag(TIF_32BIT_REGS))
 802                 return -EOPNOTSUPP;
 803
 804         /* Check the value is valid */
 805         if (value & ~known_bits)
 806                 return -EOPNOTSUPP;
 807
 808         /* Setting FRE without FR is not supported.  */
 809         if ((value & (PR_FP_MODE_FR | PR_FP_MODE_FRE)) == PR_FP_MODE_FRE)
 810                 return -EOPNOTSUPP;
 811
 812         /* Avoid inadvertently triggering emulation */
 813         if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
 814             !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
 815                 return -EOPNOTSUPP;
 816         if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
 817                 return -EOPNOTSUPP;
 818
 819         /* FR = 0 not supported in MIPS R6 */
 820         if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
 821                 return -EOPNOTSUPP;
 822
 823         /* Indicate the new FP mode in each thread */
 824         for_each_thread(task, t) {
 825                 /* Update desired FP register width */
 826                 if (value & PR_FP_MODE_FR) {
 827                         clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 828                 } else {
 829                         set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 830                         clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
 831                 }
 832
 833                 /* Update desired FP single layout */
 834                 if (value & PR_FP_MODE_FRE)
 835                         set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 836                 else
 837                         clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 838         }
 839
 840         /*
 841          * We need to ensure that all threads in the process have switched mode
 842          * before returning, in order to allow userland to not worry about
 843          * races. We can do this by forcing all CPUs that any thread in the
 844          * process may be running on to schedule something else - in this case
 845          * prepare_for_fp_mode_switch().
 846          *
 847          * We begin by generating a mask of all CPUs that any thread in the
 848          * process may be running on.
 849          */
 850         cpumask_clear(&process_cpus);
 851         for_each_thread(task, t)
 852                 cpumask_set_cpu(task_cpu(t), &process_cpus);
 853
 854         /*
 855          * Now we schedule prepare_for_fp_mode_switch() on each of those CPUs.
 856          *
 857          * The CPUs may have rescheduled already since we switched mode or
 858          * generated the cpumask, but that doesn't matter. If the task in this
 859          * process is scheduled out then our scheduling
 860          * prepare_for_fp_mode_switch() will simply be redundant. If it's
 861          * scheduled in then it will already have picked up the new FP mode
 862          * whilst doing so.
 863          */
 864         get_online_cpus();
 865         for_each_cpu_and(cpu, &process_cpus, cpu_online_mask)
 866                 work_on_cpu(cpu, prepare_for_fp_mode_switch, NULL);
 867         put_online_cpus();
 868
 869         return 0;
 870 }
 871
 872 #if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
 873 void mips_dump_regs32(u32 *uregs, const struct pt_regs *regs)
 874 {
 875         unsigned int i;
 876
 877         for (i = MIPS32_EF_R1; i <= MIPS32_EF_R31; i++) {
 878                 /* k0/k1 are copied as zero. */
 879                 if (i == MIPS32_EF_R26 || i == MIPS32_EF_R27)
 880                         uregs[i] = 0;
 881                 else
 882                         uregs[i] = regs->regs[i - MIPS32_EF_R0];
 883         }
 884
 885         uregs[MIPS32_EF_LO] = regs->lo;
 886         uregs[MIPS32_EF_HI] = regs->hi;
 887         uregs[MIPS32_EF_CP0_EPC] = regs->cp0_epc;
 888         uregs[MIPS32_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 889         uregs[MIPS32_EF_CP0_STATUS] = regs->cp0_status;
 890         uregs[MIPS32_EF_CP0_CAUSE] = regs->cp0_cause;
 891 }
 892 #endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */
 893
 894 #ifdef CONFIG_64BIT
 895 void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs)
 896 {
 897         unsigned int i;
 898
 899         for (i = MIPS64_EF_R1; i <= MIPS64_EF_R31; i++) {
 900                 /* k0/k1 are copied as zero. */
 901                 if (i == MIPS64_EF_R26 || i == MIPS64_EF_R27)
 902                         uregs[i] = 0;
 903                 else
 904                         uregs[i] = regs->regs[i - MIPS64_EF_R0];
 905         }
 906
 907         uregs[MIPS64_EF_LO] = regs->lo;
 908         uregs[MIPS64_EF_HI] = regs->hi;
 909         uregs[MIPS64_EF_CP0_EPC] = regs->cp0_epc;
 910         uregs[MIPS64_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 911         uregs[MIPS64_EF_CP0_STATUS] = regs->cp0_status;
 912         uregs[MIPS64_EF_CP0_CAUSE] = regs->cp0_cause;
 913 }
 914 #endif /* CONFIG_64BIT */