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 #include <linux/nmi.h>
  33 #include <linux/cpu.h>
  34
  35 #include <asm/abi.h>
  36 #include <asm/asm.h>
  37 #include <asm/bootinfo.h>
  38 #include <asm/cpu.h>
  39 #include <asm/dsemul.h>
  40 #include <asm/dsp.h>
  41 #include <asm/fpu.h>
  42 #include <asm/irq.h>
  43 #include <asm/mips-cps.h>
  44 #include <asm/msa.h>
  45 #include <asm/mipsregs.h>
  46 #include <asm/processor.h>
  47 #include <asm/reg.h>
  48 #include <linux/uaccess.h>
  49 #include <asm/io.h>
  50 #include <asm/elf.h>
  51 #include <asm/isadep.h>
  52 #include <asm/inst.h>
  53 #include <asm/stacktrace.h>
  54 #include <asm/irq_regs.h>
  55 #include <asm/exec.h>
  56
  57 #ifdef CONFIG_HOTPLUG_CPU
  58 void arch_cpu_idle_dead(void)
  59 {
  60         play_dead();
  61 }
  62 #endif
  63
  64 asmlinkage void ret_from_fork(void);
  65 asmlinkage void ret_from_kernel_thread(void);
  66
  67 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  68 {
  69         unsigned long status;
  70
  71         /* New thread loses kernel privileges. */
  72         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_CU2|ST0_FR|KU_MASK);
  73         status |= KU_USER;
  74         regs->cp0_status = status;
  75         lose_fpu(0);
  76         clear_thread_flag(TIF_MSA_CTX_LIVE);
  77         clear_used_math();
  78 #ifdef CONFIG_MIPS_FP_SUPPORT
  79         atomic_set(&current->thread.bd_emu_frame, BD_EMUFRAME_NONE);
  80 #endif
  81         init_dsp();
  82         regs->cp0_epc = pc;
  83         regs->regs[29] = sp;
  84 }
  85
  86 void exit_thread(struct task_struct *tsk)
  87 {
  88         /*
  89          * User threads may have allocated a delay slot emulation frame.
  90          * If so, clean up that allocation.
  91          */
  92         if (!(current->flags & PF_KTHREAD))
  93                 dsemul_thread_cleanup(tsk);
  94 }
  95
  96 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  97 {
  98         /*
  99          * Save any process state which is live in hardware registers to the
 100          * parent context prior to duplication. This prevents the new child
 101          * state becoming stale if the parent is preempted before copy_thread()
 102          * gets a chance to save the parent's live hardware registers to the
 103          * child context.
 104          */
 105         preempt_disable();
 106
 107         if (is_msa_enabled())
 108                 save_msa(current);
 109         else if (is_fpu_owner())
 110                 _save_fp(current);
 111
 112         save_dsp(current);
 113
 114         preempt_enable();
 115
 116         *dst = *src;
 117         return 0;
 118 }
 119
 120 /*
 121  * Copy architecture-specific thread state
 122  */
 123 int copy_thread(unsigned long clone_flags, unsigned long usp,
 124                 unsigned long kthread_arg, struct task_struct *p,
 125                 unsigned long tls)
 126 {
 127         struct thread_info *ti = task_thread_info(p);
 128         struct pt_regs *childregs, *regs = current_pt_regs();
 129         unsigned long childksp;
 130
 131         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 132
 133         /* set up new TSS. */
 134         childregs = (struct pt_regs *) childksp - 1;
 135         /*  Put the stack after the struct pt_regs.  */
 136         childksp = (unsigned long) childregs;
 137         p->thread.cp0_status = (read_c0_status() & ~(ST0_CU2|ST0_CU1)) | ST0_KERNEL_CUMASK;
 138         if (unlikely(p->flags & PF_KTHREAD)) {
 139                 /* kernel thread */
 140                 unsigned long status = p->thread.cp0_status;
 141                 memset(childregs, 0, sizeof(struct pt_regs));
 142                 ti->addr_limit = KERNEL_DS;
 143                 p->thread.reg16 = usp; /* fn */
 144                 p->thread.reg17 = kthread_arg;
 145                 p->thread.reg29 = childksp;
 146                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 147 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 148                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 149                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 150 #else
 151                 status |= ST0_EXL;
 152 #endif
 153                 childregs->cp0_status = status;
 154                 return 0;
 155         }
 156
 157         /* user thread */
 158         *childregs = *regs;
 159         childregs->regs[7] = 0; /* Clear error flag */
 160         childregs->regs[2] = 0; /* Child gets zero as return value */
 161         if (usp)
 162                 childregs->regs[29] = usp;
 163         ti->addr_limit = USER_DS;
 164
 165         p->thread.reg29 = (unsigned long) childregs;
 166         p->thread.reg31 = (unsigned long) ret_from_fork;
 167
 168         /*
 169          * New tasks lose permission to use the fpu. This accelerates context
 170          * switching for most programs since they don't use the fpu.
 171          */
 172         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 173
 174         clear_tsk_thread_flag(p, TIF_USEDFPU);
 175         clear_tsk_thread_flag(p, TIF_USEDMSA);
 176         clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
 177
 178 #ifdef CONFIG_MIPS_MT_FPAFF
 179         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 180 #endif /* CONFIG_MIPS_MT_FPAFF */
 181
 182 #ifdef CONFIG_MIPS_FP_SUPPORT
 183         atomic_set(&p->thread.bd_emu_frame, BD_EMUFRAME_NONE);
 184 #endif
 185
 186         if (clone_flags & CLONE_SETTLS)
 187                 ti->tp_value = tls;
 188
 189         return 0;
 190 }
 191
 192 #ifdef CONFIG_STACKPROTECTOR
 193 #include <linux/stackprotector.h>
 194 unsigned long __stack_chk_guard __read_mostly;
 195 EXPORT_SYMBOL(__stack_chk_guard);
 196 #endif
 197
 198 struct mips_frame_info {
 199         void            *func;
 200         unsigned long   func_size;
 201         int             frame_size;
 202         int             pc_offset;
 203 };
 204
 205 #define J_TARGET(pc,target)     \
 206                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 207
 208 static inline int is_ra_save_ins(union mips_instruction *ip, int *poff)
 209 {
 210 #ifdef CONFIG_CPU_MICROMIPS
 211         /*
 212          * swsp ra,offset
 213          * swm16 reglist,offset(sp)
 214          * swm32 reglist,offset(sp)
 215          * sw32 ra,offset(sp)
 216          * jradiussp - NOT SUPPORTED
 217          *
 218          * microMIPS is way more fun...
 219          */
 220         if (mm_insn_16bit(ip->word >> 16)) {
 221                 switch (ip->mm16_r5_format.opcode) {
 222                 case mm_swsp16_op:
 223                         if (ip->mm16_r5_format.rt != 31)
 224                                 return 0;
 225
 226                         *poff = ip->mm16_r5_format.imm;
 227                         *poff = (*poff << 2) / sizeof(ulong);
 228                         return 1;
 229
 230                 case mm_pool16c_op:
 231                         switch (ip->mm16_m_format.func) {
 232                         case mm_swm16_op:
 233                                 *poff = ip->mm16_m_format.imm;
 234                                 *poff += 1 + ip->mm16_m_format.rlist;
 235                                 *poff = (*poff << 2) / sizeof(ulong);
 236                                 return 1;
 237
 238                         default:
 239                                 return 0;
 240                         }
 241
 242                 default:
 243                         return 0;
 244                 }
 245         }
 246
 247         switch (ip->i_format.opcode) {
 248         case mm_sw32_op:
 249                 if (ip->i_format.rs != 29)
 250                         return 0;
 251                 if (ip->i_format.rt != 31)
 252                         return 0;
 253
 254                 *poff = ip->i_format.simmediate / sizeof(ulong);
 255                 return 1;
 256
 257         case mm_pool32b_op:
 258                 switch (ip->mm_m_format.func) {
 259                 case mm_swm32_func:
 260                         if (ip->mm_m_format.rd < 0x10)
 261                                 return 0;
 262                         if (ip->mm_m_format.base != 29)
 263                                 return 0;
 264
 265                         *poff = ip->mm_m_format.simmediate;
 266                         *poff += (ip->mm_m_format.rd & 0xf) * sizeof(u32);
 267                         *poff /= sizeof(ulong);
 268                         return 1;
 269                 default:
 270                         return 0;
 271                 }
 272
 273         default:
 274                 return 0;
 275         }
 276 #else
 277         /* sw / sd $ra, offset($sp) */
 278         if ((ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 279                 ip->i_format.rs == 29 && ip->i_format.rt == 31) {
 280                 *poff = ip->i_format.simmediate / sizeof(ulong);
 281                 return 1;
 282         }
 283 #ifdef CONFIG_CPU_LOONGSON64
 284         if ((ip->loongson3_lswc2_format.opcode == swc2_op) &&
 285                       (ip->loongson3_lswc2_format.ls == 1) &&
 286                       (ip->loongson3_lswc2_format.fr == 0) &&
 287                       (ip->loongson3_lswc2_format.base == 29)) {
 288                 if (ip->loongson3_lswc2_format.rt == 31) {
 289                         *poff = ip->loongson3_lswc2_format.offset << 1;
 290                         return 1;
 291                 }
 292                 if (ip->loongson3_lswc2_format.rq == 31) {
 293                         *poff = (ip->loongson3_lswc2_format.offset << 1) + 1;
 294                         return 1;
 295                 }
 296         }
 297 #endif
 298         return 0;
 299 #endif
 300 }
 301
 302 static inline int is_jump_ins(union mips_instruction *ip)
 303 {
 304 #ifdef CONFIG_CPU_MICROMIPS
 305         /*
 306          * jr16,jrc,jalr16,jalr16
 307          * jal
 308          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 309          * jraddiusp - NOT SUPPORTED
 310          *
 311          * microMIPS is kind of more fun...
 312          */
 313         if (mm_insn_16bit(ip->word >> 16)) {
 314                 if ((ip->mm16_r5_format.opcode == mm_pool16c_op &&
 315                     (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op))
 316                         return 1;
 317                 return 0;
 318         }
 319
 320         if (ip->j_format.opcode == mm_j32_op)
 321                 return 1;
 322         if (ip->j_format.opcode == mm_jal32_op)
 323                 return 1;
 324         if (ip->r_format.opcode != mm_pool32a_op ||
 325                         ip->r_format.func != mm_pool32axf_op)
 326                 return 0;
 327         return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 328 #else
 329         if (ip->j_format.opcode == j_op)
 330                 return 1;
 331         if (ip->j_format.opcode == jal_op)
 332                 return 1;
 333         if (ip->r_format.opcode != spec_op)
 334                 return 0;
 335         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 336 #endif
 337 }
 338
 339 static inline int is_sp_move_ins(union mips_instruction *ip, int *frame_size)
 340 {
 341 #ifdef CONFIG_CPU_MICROMIPS
 342         unsigned short tmp;
 343
 344         /*
 345          * addiusp -imm
 346          * addius5 sp,-imm
 347          * addiu32 sp,sp,-imm
 348          * jradiussp - NOT SUPPORTED
 349          *
 350          * microMIPS is not more fun...
 351          */
 352         if (mm_insn_16bit(ip->word >> 16)) {
 353                 if (ip->mm16_r3_format.opcode == mm_pool16d_op &&
 354                     ip->mm16_r3_format.simmediate & mm_addiusp_func) {
 355                         tmp = ip->mm_b0_format.simmediate >> 1;
 356                         tmp = ((tmp & 0x1ff) ^ 0x100) - 0x100;
 357                         if ((tmp + 2) < 4) /* 0x0,0x1,0x1fe,0x1ff are special */
 358                                 tmp ^= 0x100;
 359                         *frame_size = -(signed short)(tmp << 2);
 360                         return 1;
 361                 }
 362                 if (ip->mm16_r5_format.opcode == mm_pool16d_op &&
 363                     ip->mm16_r5_format.rt == 29) {
 364                         tmp = ip->mm16_r5_format.imm >> 1;
 365                         *frame_size = -(signed short)(tmp & 0xf);
 366                         return 1;
 367                 }
 368                 return 0;
 369         }
 370
 371         if (ip->mm_i_format.opcode == mm_addiu32_op &&
 372             ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29) {
 373                 *frame_size = -ip->i_format.simmediate;
 374                 return 1;
 375         }
 376 #else
 377         /* addiu/daddiu sp,sp,-imm */
 378         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 379                 return 0;
 380
 381         if (ip->i_format.opcode == addiu_op ||
 382             ip->i_format.opcode == daddiu_op) {
 383                 *frame_size = -ip->i_format.simmediate;
 384                 return 1;
 385         }
 386 #endif
 387         return 0;
 388 }
 389
 390 static int get_frame_info(struct mips_frame_info *info)
 391 {
 392         bool is_mmips = IS_ENABLED(CONFIG_CPU_MICROMIPS);
 393         union mips_instruction insn, *ip;
 394         const unsigned int max_insns = 128;
 395         unsigned int last_insn_size = 0;
 396         unsigned int i;
 397         bool saw_jump = false;
 398
 399         info->pc_offset = -1;
 400         info->frame_size = 0;
 401
 402         ip = (void *)msk_isa16_mode((ulong)info->func);
 403         if (!ip)
 404                 goto err;
 405
 406         for (i = 0; i < max_insns; i++) {
 407                 ip = (void *)ip + last_insn_size;
 408
 409                 if (is_mmips && mm_insn_16bit(ip->halfword[0])) {
 410                         insn.word = ip->halfword[0] << 16;
 411                         last_insn_size = 2;
 412                 } else if (is_mmips) {
 413                         insn.word = ip->halfword[0] << 16 | ip->halfword[1];
 414                         last_insn_size = 4;
 415                 } else {
 416                         insn.word = ip->word;
 417                         last_insn_size = 4;
 418                 }
 419
 420                 if (!info->frame_size) {
 421                         is_sp_move_ins(&insn, &info->frame_size);
 422                         continue;
 423                 } else if (!saw_jump && is_jump_ins(ip)) {
 424                         /*
 425                          * If we see a jump instruction, we are finished
 426                          * with the frame save.
 427                          *
 428                          * Some functions can have a shortcut return at
 429                          * the beginning of the function, so don't start
 430                          * looking for jump instruction until we see the
 431                          * frame setup.
 432                          *
 433                          * The RA save instruction can get put into the
 434                          * delay slot of the jump instruction, so look
 435                          * at the next instruction, too.
 436                          */
 437                         saw_jump = true;
 438                         continue;
 439                 }
 440                 if (info->pc_offset == -1 &&
 441                     is_ra_save_ins(&insn, &info->pc_offset))
 442                         break;
 443                 if (saw_jump)
 444                         break;
 445         }
 446         if (info->frame_size && info->pc_offset >= 0) /* nested */
 447                 return 0;
 448         if (info->pc_offset < 0) /* leaf */
 449                 return 1;
 450         /* prologue seems bogus... */
 451 err:
 452         return -1;
 453 }
 454
 455 static struct mips_frame_info schedule_mfi __read_mostly;
 456
 457 #ifdef CONFIG_KALLSYMS
 458 static unsigned long get___schedule_addr(void)
 459 {
 460         return kallsyms_lookup_name("__schedule");
 461 }
 462 #else
 463 static unsigned long get___schedule_addr(void)
 464 {
 465         union mips_instruction *ip = (void *)schedule;
 466         int max_insns = 8;
 467         int i;
 468
 469         for (i = 0; i < max_insns; i++, ip++) {
 470                 if (ip->j_format.opcode == j_op)
 471                         return J_TARGET(ip, ip->j_format.target);
 472         }
 473         return 0;
 474 }
 475 #endif
 476
 477 static int __init frame_info_init(void)
 478 {
 479         unsigned long size = 0;
 480 #ifdef CONFIG_KALLSYMS
 481         unsigned long ofs;
 482 #endif
 483         unsigned long addr;
 484
 485         addr = get___schedule_addr();
 486         if (!addr)
 487                 addr = (unsigned long)schedule;
 488
 489 #ifdef CONFIG_KALLSYMS
 490         kallsyms_lookup_size_offset(addr, &size, &ofs);
 491 #endif
 492         schedule_mfi.func = (void *)addr;
 493         schedule_mfi.func_size = size;
 494
 495         get_frame_info(&schedule_mfi);
 496
 497         /*
 498          * Without schedule() frame info, result given by
 499          * thread_saved_pc() and get_wchan() are not reliable.
 500          */
 501         if (schedule_mfi.pc_offset < 0)
 502                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 503
 504         return 0;
 505 }
 506
 507 arch_initcall(frame_info_init);
 508
 509 /*
 510  * Return saved PC of a blocked thread.
 511  */
 512 static unsigned long thread_saved_pc(struct task_struct *tsk)
 513 {
 514         struct thread_struct *t = &tsk->thread;
 515
 516         /* New born processes are a special case */
 517         if (t->reg31 == (unsigned long) ret_from_fork)
 518                 return t->reg31;
 519         if (schedule_mfi.pc_offset < 0)
 520                 return 0;
 521         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 522 }
 523
 524
 525 #ifdef CONFIG_KALLSYMS
 526 /* generic stack unwinding function */
 527 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 528                                               unsigned long *sp,
 529                                               unsigned long pc,
 530                                               unsigned long *ra)
 531 {
 532         unsigned long low, high, irq_stack_high;
 533         struct mips_frame_info info;
 534         unsigned long size, ofs;
 535         struct pt_regs *regs;
 536         int leaf;
 537
 538         if (!stack_page)
 539                 return 0;
 540
 541         /*
 542          * IRQ stacks start at IRQ_STACK_START
 543          * task stacks at THREAD_SIZE - 32
 544          */
 545         low = stack_page;
 546         if (!preemptible() && on_irq_stack(raw_smp_processor_id(), *sp)) {
 547                 high = stack_page + IRQ_STACK_START;
 548                 irq_stack_high = high;
 549         } else {
 550                 high = stack_page + THREAD_SIZE - 32;
 551                 irq_stack_high = 0;
 552         }
 553
 554         /*
 555          * If we reached the top of the interrupt stack, start unwinding
 556          * the interrupted task stack.
 557          */
 558         if (unlikely(*sp == irq_stack_high)) {
 559                 unsigned long task_sp = *(unsigned long *)*sp;
 560
 561                 /*
 562                  * Check that the pointer saved in the IRQ stack head points to
 563                  * something within the stack of the current task
 564                  */
 565                 if (!object_is_on_stack((void *)task_sp))
 566                         return 0;
 567
 568                 /*
 569                  * Follow pointer to tasks kernel stack frame where interrupted
 570                  * state was saved.
 571                  */
 572                 regs = (struct pt_regs *)task_sp;
 573                 pc = regs->cp0_epc;
 574                 if (!user_mode(regs) && __kernel_text_address(pc)) {
 575                         *sp = regs->regs[29];
 576                         *ra = regs->regs[31];
 577                         return pc;
 578                 }
 579                 return 0;
 580         }
 581         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 582                 return 0;
 583         /*
 584          * Return ra if an exception occurred at the first instruction
 585          */
 586         if (unlikely(ofs == 0)) {
 587                 pc = *ra;
 588                 *ra = 0;
 589                 return pc;
 590         }
 591
 592         info.func = (void *)(pc - ofs);
 593         info.func_size = ofs;   /* analyze from start to ofs */
 594         leaf = get_frame_info(&info);
 595         if (leaf < 0)
 596                 return 0;
 597
 598         if (*sp < low || *sp + info.frame_size > high)
 599                 return 0;
 600
 601         if (leaf)
 602                 /*
 603                  * For some extreme cases, get_frame_info() can
 604                  * consider wrongly a nested function as a leaf
 605                  * one. In that cases avoid to return always the
 606                  * same value.
 607                  */
 608                 pc = pc != *ra ? *ra : 0;
 609         else
 610                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 611
 612         *sp += info.frame_size;
 613         *ra = 0;
 614         return __kernel_text_address(pc) ? pc : 0;
 615 }
 616 EXPORT_SYMBOL(unwind_stack_by_address);
 617
 618 /* used by show_backtrace() */
 619 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 620                            unsigned long pc, unsigned long *ra)
 621 {
 622         unsigned long stack_page = 0;
 623         int cpu;
 624
 625         for_each_possible_cpu(cpu) {
 626                 if (on_irq_stack(cpu, *sp)) {
 627                         stack_page = (unsigned long)irq_stack[cpu];
 628                         break;
 629                 }
 630         }
 631
 632         if (!stack_page)
 633                 stack_page = (unsigned long)task_stack_page(task);
 634
 635         return unwind_stack_by_address(stack_page, sp, pc, ra);
 636 }
 637 #endif
 638
 639 /*
 640  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 641  */
 642 unsigned long get_wchan(struct task_struct *task)
 643 {
 644         unsigned long pc = 0;
 645 #ifdef CONFIG_KALLSYMS
 646         unsigned long sp;
 647         unsigned long ra = 0;
 648 #endif
 649
 650         if (!task || task == current || task->state == TASK_RUNNING)
 651                 goto out;
 652         if (!task_stack_page(task))
 653                 goto out;
 654
 655         pc = thread_saved_pc(task);
 656
 657 #ifdef CONFIG_KALLSYMS
 658         sp = task->thread.reg29 + schedule_mfi.frame_size;
 659
 660         while (in_sched_functions(pc))
 661                 pc = unwind_stack(task, &sp, pc, &ra);
 662 #endif
 663
 664 out:
 665         return pc;
 666 }
 667
 668 unsigned long mips_stack_top(void)
 669 {
 670         unsigned long top = TASK_SIZE & PAGE_MASK;
 671
 672         if (IS_ENABLED(CONFIG_MIPS_FP_SUPPORT)) {
 673                 /* One page for branch delay slot "emulation" */
 674                 top -= PAGE_SIZE;
 675         }
 676
 677         /* Space for the VDSO, data page & GIC user page */
 678         top -= PAGE_ALIGN(current->thread.abi->vdso->size);
 679         top -= PAGE_SIZE;
 680         top -= mips_gic_present() ? PAGE_SIZE : 0;
 681
 682         /* Space for cache colour alignment */
 683         if (cpu_has_dc_aliases)
 684                 top -= shm_align_mask + 1;
 685
 686         /* Space to randomize the VDSO base */
 687         if (current->flags & PF_RANDOMIZE)
 688                 top -= VDSO_RANDOMIZE_SIZE;
 689
 690         return top;
 691 }
 692
 693 /*
 694  * Don't forget that the stack pointer must be aligned on a 8 bytes
 695  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 696  */
 697 unsigned long arch_align_stack(unsigned long sp)
 698 {
 699         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 700                 sp -= get_random_int() & ~PAGE_MASK;
 701
 702         return sp & ALMASK;
 703 }
 704
 705 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
 706 static struct cpumask backtrace_csd_busy;
 707
 708 static void handle_backtrace(void *info)
 709 {
 710         nmi_cpu_backtrace(get_irq_regs());
 711         cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
 712 }
 713
 714 static void raise_backtrace(cpumask_t *mask)
 715 {
 716         call_single_data_t *csd;
 717         int cpu;
 718
 719         for_each_cpu(cpu, mask) {
 720                 /*
 721                  * If we previously sent an IPI to the target CPU & it hasn't
 722                  * cleared its bit in the busy cpumask then it didn't handle
 723                  * our previous IPI & it's not safe for us to reuse the
 724                  * call_single_data_t.
 725                  */
 726                 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
 727                         pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
 728                                 cpu);
 729                         continue;
 730                 }
 731
 732                 csd = &per_cpu(backtrace_csd, cpu);
 733                 csd->func = handle_backtrace;
 734                 smp_call_function_single_async(cpu, csd);
 735         }
 736 }
 737
 738 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 739 {
 740         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
 741 }
 742
 743 int mips_get_process_fp_mode(struct task_struct *task)
 744 {
 745         int value = 0;
 746
 747         if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
 748                 value |= PR_FP_MODE_FR;
 749         if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
 750                 value |= PR_FP_MODE_FRE;
 751
 752         return value;
 753 }
 754
 755 static long prepare_for_fp_mode_switch(void *unused)
 756 {
 757         /*
 758          * This is icky, but we use this to simply ensure that all CPUs have
 759          * context switched, regardless of whether they were previously running
 760          * kernel or user code. This ensures that no CPU that a mode-switching
 761          * program may execute on keeps its FPU enabled (& in the old mode)
 762          * throughout the mode switch.
 763          */
 764         return 0;
 765 }
 766
 767 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 768 {
 769         const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
 770         struct task_struct *t;
 771         struct cpumask process_cpus;
 772         int cpu;
 773
 774         /* If nothing to change, return right away, successfully.  */
 775         if (value == mips_get_process_fp_mode(task))
 776                 return 0;
 777
 778         /* Only accept a mode change if 64-bit FP enabled for o32.  */
 779         if (!IS_ENABLED(CONFIG_MIPS_O32_FP64_SUPPORT))
 780                 return -EOPNOTSUPP;
 781
 782         /* And only for o32 tasks.  */
 783         if (IS_ENABLED(CONFIG_64BIT) && !test_thread_flag(TIF_32BIT_REGS))
 784                 return -EOPNOTSUPP;
 785
 786         /* Check the value is valid */
 787         if (value & ~known_bits)
 788                 return -EOPNOTSUPP;
 789
 790         /* Setting FRE without FR is not supported.  */
 791         if ((value & (PR_FP_MODE_FR | PR_FP_MODE_FRE)) == PR_FP_MODE_FRE)
 792                 return -EOPNOTSUPP;
 793
 794         /* Avoid inadvertently triggering emulation */
 795         if ((value & PR_FP_MODE_FR) && raw_cpu_has_fpu &&
 796             !(raw_current_cpu_data.fpu_id & MIPS_FPIR_F64))
 797                 return -EOPNOTSUPP;
 798         if ((value & PR_FP_MODE_FRE) && raw_cpu_has_fpu && !cpu_has_fre)
 799                 return -EOPNOTSUPP;
 800
 801         /* FR = 0 not supported in MIPS R6 */
 802         if (!(value & PR_FP_MODE_FR) && raw_cpu_has_fpu && cpu_has_mips_r6)
 803                 return -EOPNOTSUPP;
 804
 805         /* Indicate the new FP mode in each thread */
 806         for_each_thread(task, t) {
 807                 /* Update desired FP register width */
 808                 if (value & PR_FP_MODE_FR) {
 809                         clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 810                 } else {
 811                         set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 812                         clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
 813                 }
 814
 815                 /* Update desired FP single layout */
 816                 if (value & PR_FP_MODE_FRE)
 817                         set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 818                 else
 819                         clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 820         }
 821
 822         /*
 823          * We need to ensure that all threads in the process have switched mode
 824          * before returning, in order to allow userland to not worry about
 825          * races. We can do this by forcing all CPUs that any thread in the
 826          * process may be running on to schedule something else - in this case
 827          * prepare_for_fp_mode_switch().
 828          *
 829          * We begin by generating a mask of all CPUs that any thread in the
 830          * process may be running on.
 831          */
 832         cpumask_clear(&process_cpus);
 833         for_each_thread(task, t)
 834                 cpumask_set_cpu(task_cpu(t), &process_cpus);
 835
 836         /*
 837          * Now we schedule prepare_for_fp_mode_switch() on each of those CPUs.
 838          *
 839          * The CPUs may have rescheduled already since we switched mode or
 840          * generated the cpumask, but that doesn't matter. If the task in this
 841          * process is scheduled out then our scheduling
 842          * prepare_for_fp_mode_switch() will simply be redundant. If it's
 843          * scheduled in then it will already have picked up the new FP mode
 844          * whilst doing so.
 845          */
 846         get_online_cpus();
 847         for_each_cpu_and(cpu, &process_cpus, cpu_online_mask)
 848                 work_on_cpu(cpu, prepare_for_fp_mode_switch, NULL);
 849         put_online_cpus();
 850
 851         return 0;
 852 }
 853
 854 #if defined(CONFIG_32BIT) || defined(CONFIG_MIPS32_O32)
 855 void mips_dump_regs32(u32 *uregs, const struct pt_regs *regs)
 856 {
 857         unsigned int i;
 858
 859         for (i = MIPS32_EF_R1; i <= MIPS32_EF_R31; i++) {
 860                 /* k0/k1 are copied as zero. */
 861                 if (i == MIPS32_EF_R26 || i == MIPS32_EF_R27)
 862                         uregs[i] = 0;
 863                 else
 864                         uregs[i] = regs->regs[i - MIPS32_EF_R0];
 865         }
 866
 867         uregs[MIPS32_EF_LO] = regs->lo;
 868         uregs[MIPS32_EF_HI] = regs->hi;
 869         uregs[MIPS32_EF_CP0_EPC] = regs->cp0_epc;
 870         uregs[MIPS32_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 871         uregs[MIPS32_EF_CP0_STATUS] = regs->cp0_status;
 872         uregs[MIPS32_EF_CP0_CAUSE] = regs->cp0_cause;
 873 }
 874 #endif /* CONFIG_32BIT || CONFIG_MIPS32_O32 */
 875
 876 #ifdef CONFIG_64BIT
 877 void mips_dump_regs64(u64 *uregs, const struct pt_regs *regs)
 878 {
 879         unsigned int i;
 880
 881         for (i = MIPS64_EF_R1; i <= MIPS64_EF_R31; i++) {
 882                 /* k0/k1 are copied as zero. */
 883                 if (i == MIPS64_EF_R26 || i == MIPS64_EF_R27)
 884                         uregs[i] = 0;
 885                 else
 886                         uregs[i] = regs->regs[i - MIPS64_EF_R0];
 887         }
 888
 889         uregs[MIPS64_EF_LO] = regs->lo;
 890         uregs[MIPS64_EF_HI] = regs->hi;
 891         uregs[MIPS64_EF_CP0_EPC] = regs->cp0_epc;
 892         uregs[MIPS64_EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 893         uregs[MIPS64_EF_CP0_STATUS] = regs->cp0_status;
 894         uregs[MIPS64_EF_CP0_CAUSE] = regs->cp0_cause;
 895 }
 896 #endif /* CONFIG_64BIT */