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/dsp.h>
  34 #include <asm/fpu.h>
  35 #include <asm/msa.h>
  36 #include <asm/pgtable.h>
  37 #include <asm/mipsregs.h>
  38 #include <asm/processor.h>
  39 #include <asm/reg.h>
  40 #include <asm/uaccess.h>
  41 #include <asm/io.h>
  42 #include <asm/elf.h>
  43 #include <asm/isadep.h>
  44 #include <asm/inst.h>
  45 #include <asm/stacktrace.h>
  46 #include <asm/irq_regs.h>
  47
  48 #ifdef CONFIG_HOTPLUG_CPU
  49 void arch_cpu_idle_dead(void)
  50 {
  51         /* What the heck is this check doing ? */
  52         if (!cpumask_test_cpu(smp_processor_id(), &cpu_callin_map))
  53                 play_dead();
  54 }
  55 #endif
  56
  57 asmlinkage void ret_from_fork(void);
  58 asmlinkage void ret_from_kernel_thread(void);
  59
  60 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  61 {
  62         unsigned long status;
  63
  64         /* New thread loses kernel privileges. */
  65         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
  66         status |= KU_USER;
  67         regs->cp0_status = status;
  68         lose_fpu(0);
  69         clear_thread_flag(TIF_MSA_CTX_LIVE);
  70         clear_used_math();
  71         init_dsp();
  72         regs->cp0_epc = pc;
  73         regs->regs[29] = sp;
  74 }
  75
  76 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  77 {
  78         /*
  79          * Save any process state which is live in hardware registers to the
  80          * parent context prior to duplication. This prevents the new child
  81          * state becoming stale if the parent is preempted before copy_thread()
  82          * gets a chance to save the parent's live hardware registers to the
  83          * child context.
  84          */
  85         preempt_disable();
  86
  87         if (is_msa_enabled())
  88                 save_msa(current);
  89         else if (is_fpu_owner())
  90                 _save_fp(current);
  91
  92         save_dsp(current);
  93
  94         preempt_enable();
  95
  96         *dst = *src;
  97         return 0;
  98 }
  99
 100 /*
 101  * Copy architecture-specific thread state
 102  */
 103 int copy_thread(unsigned long clone_flags, unsigned long usp,
 104         unsigned long kthread_arg, struct task_struct *p)
 105 {
 106         struct thread_info *ti = task_thread_info(p);
 107         struct pt_regs *childregs, *regs = current_pt_regs();
 108         unsigned long childksp;
 109         p->set_child_tid = p->clear_child_tid = NULL;
 110
 111         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 112
 113         /* set up new TSS. */
 114         childregs = (struct pt_regs *) childksp - 1;
 115         /*  Put the stack after the struct pt_regs.  */
 116         childksp = (unsigned long) childregs;
 117         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 118         if (unlikely(p->flags & PF_KTHREAD)) {
 119                 /* kernel thread */
 120                 unsigned long status = p->thread.cp0_status;
 121                 memset(childregs, 0, sizeof(struct pt_regs));
 122                 ti->addr_limit = KERNEL_DS;
 123                 p->thread.reg16 = usp; /* fn */
 124                 p->thread.reg17 = kthread_arg;
 125                 p->thread.reg29 = childksp;
 126                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 127 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 128                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 129                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 130 #else
 131                 status |= ST0_EXL;
 132 #endif
 133                 childregs->cp0_status = status;
 134                 return 0;
 135         }
 136
 137         /* user thread */
 138         *childregs = *regs;
 139         childregs->regs[7] = 0; /* Clear error flag */
 140         childregs->regs[2] = 0; /* Child gets zero as return value */
 141         if (usp)
 142                 childregs->regs[29] = usp;
 143         ti->addr_limit = USER_DS;
 144
 145         p->thread.reg29 = (unsigned long) childregs;
 146         p->thread.reg31 = (unsigned long) ret_from_fork;
 147
 148         /*
 149          * New tasks lose permission to use the fpu. This accelerates context
 150          * switching for most programs since they don't use the fpu.
 151          */
 152         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 153
 154         clear_tsk_thread_flag(p, TIF_USEDFPU);
 155         clear_tsk_thread_flag(p, TIF_USEDMSA);
 156         clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
 157
 158 #ifdef CONFIG_MIPS_MT_FPAFF
 159         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 160 #endif /* CONFIG_MIPS_MT_FPAFF */
 161
 162         if (clone_flags & CLONE_SETTLS)
 163                 ti->tp_value = regs->regs[7];
 164
 165         return 0;
 166 }
 167
 168 #ifdef CONFIG_CC_STACKPROTECTOR
 169 #include <linux/stackprotector.h>
 170 unsigned long __stack_chk_guard __read_mostly;
 171 EXPORT_SYMBOL(__stack_chk_guard);
 172 #endif
 173
 174 struct mips_frame_info {
 175         void            *func;
 176         unsigned long   func_size;
 177         int             frame_size;
 178         int             pc_offset;
 179 };
 180
 181 #define J_TARGET(pc,target)     \
 182                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 183
 184 static inline int is_ra_save_ins(union mips_instruction *ip)
 185 {
 186 #ifdef CONFIG_CPU_MICROMIPS
 187         union mips_instruction mmi;
 188
 189         /*
 190          * swsp ra,offset
 191          * swm16 reglist,offset(sp)
 192          * swm32 reglist,offset(sp)
 193          * sw32 ra,offset(sp)
 194          * jradiussp - NOT SUPPORTED
 195          *
 196          * microMIPS is way more fun...
 197          */
 198         if (mm_insn_16bit(ip->halfword[0])) {
 199                 mmi.word = (ip->halfword[0] << 16);
 200                 return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
 201                         mmi.mm16_r5_format.rt == 31) ||
 202                        (mmi.mm16_m_format.opcode == mm_pool16c_op &&
 203                         mmi.mm16_m_format.func == mm_swm16_op);
 204         }
 205         else {
 206                 mmi.halfword[0] = ip->halfword[1];
 207                 mmi.halfword[1] = ip->halfword[0];
 208                 return (mmi.mm_m_format.opcode == mm_pool32b_op &&
 209                         mmi.mm_m_format.rd > 9 &&
 210                         mmi.mm_m_format.base == 29 &&
 211                         mmi.mm_m_format.func == mm_swm32_func) ||
 212                        (mmi.i_format.opcode == mm_sw32_op &&
 213                         mmi.i_format.rs == 29 &&
 214                         mmi.i_format.rt == 31);
 215         }
 216 #else
 217         /* sw / sd $ra, offset($sp) */
 218         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 219                 ip->i_format.rs == 29 &&
 220                 ip->i_format.rt == 31;
 221 #endif
 222 }
 223
 224 static inline int is_jump_ins(union mips_instruction *ip)
 225 {
 226 #ifdef CONFIG_CPU_MICROMIPS
 227         /*
 228          * jr16,jrc,jalr16,jalr16
 229          * jal
 230          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 231          * jraddiusp - NOT SUPPORTED
 232          *
 233          * microMIPS is kind of more fun...
 234          */
 235         union mips_instruction mmi;
 236
 237         mmi.word = (ip->halfword[0] << 16);
 238
 239         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
 240             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
 241             ip->j_format.opcode == mm_jal32_op)
 242                 return 1;
 243         if (ip->r_format.opcode != mm_pool32a_op ||
 244                         ip->r_format.func != mm_pool32axf_op)
 245                 return 0;
 246         return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 247 #else
 248         if (ip->j_format.opcode == j_op)
 249                 return 1;
 250         if (ip->j_format.opcode == jal_op)
 251                 return 1;
 252         if (ip->r_format.opcode != spec_op)
 253                 return 0;
 254         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 255 #endif
 256 }
 257
 258 static inline int is_sp_move_ins(union mips_instruction *ip)
 259 {
 260 #ifdef CONFIG_CPU_MICROMIPS
 261         /*
 262          * addiusp -imm
 263          * addius5 sp,-imm
 264          * addiu32 sp,sp,-imm
 265          * jradiussp - NOT SUPPORTED
 266          *
 267          * microMIPS is not more fun...
 268          */
 269         if (mm_insn_16bit(ip->halfword[0])) {
 270                 union mips_instruction mmi;
 271
 272                 mmi.word = (ip->halfword[0] << 16);
 273                 return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
 274                         mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
 275                        (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
 276                         mmi.mm16_r5_format.rt == 29);
 277         }
 278         return ip->mm_i_format.opcode == mm_addiu32_op &&
 279                ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
 280 #else
 281         /* addiu/daddiu sp,sp,-imm */
 282         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 283                 return 0;
 284         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 285                 return 1;
 286 #endif
 287         return 0;
 288 }
 289
 290 static int get_frame_info(struct mips_frame_info *info)
 291 {
 292 #ifdef CONFIG_CPU_MICROMIPS
 293         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
 294 #else
 295         union mips_instruction *ip = info->func;
 296 #endif
 297         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 298         unsigned i;
 299
 300         info->pc_offset = -1;
 301         info->frame_size = 0;
 302
 303         if (!ip)
 304                 goto err;
 305
 306         if (max_insns == 0)
 307                 max_insns = 128U;       /* unknown function size */
 308         max_insns = min(128U, max_insns);
 309
 310         for (i = 0; i < max_insns; i++, ip++) {
 311
 312                 if (is_jump_ins(ip))
 313                         break;
 314                 if (!info->frame_size) {
 315                         if (is_sp_move_ins(ip))
 316                         {
 317 #ifdef CONFIG_CPU_MICROMIPS
 318                                 if (mm_insn_16bit(ip->halfword[0]))
 319                                 {
 320                                         unsigned short tmp;
 321
 322                                         if (ip->halfword[0] & mm_addiusp_func)
 323                                         {
 324                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 325                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 326                                         } else {
 327                                                 tmp = (ip->halfword[0] >> 1);
 328                                                 info->frame_size = -(signed short)(tmp & 0xf);
 329                                         }
 330                                         ip = (void *) &ip->halfword[1];
 331                                         ip--;
 332                                 } else
 333 #endif
 334                                 info->frame_size = - ip->i_format.simmediate;
 335                         }
 336                         continue;
 337                 }
 338                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
 339                         info->pc_offset =
 340                                 ip->i_format.simmediate / sizeof(long);
 341                         break;
 342                 }
 343         }
 344         if (info->frame_size && info->pc_offset >= 0) /* nested */
 345                 return 0;
 346         if (info->pc_offset < 0) /* leaf */
 347                 return 1;
 348         /* prologue seems bogus... */
 349 err:
 350         return -1;
 351 }
 352
 353 static struct mips_frame_info schedule_mfi __read_mostly;
 354
 355 #ifdef CONFIG_KALLSYMS
 356 static unsigned long get___schedule_addr(void)
 357 {
 358         return kallsyms_lookup_name("__schedule");
 359 }
 360 #else
 361 static unsigned long get___schedule_addr(void)
 362 {
 363         union mips_instruction *ip = (void *)schedule;
 364         int max_insns = 8;
 365         int i;
 366
 367         for (i = 0; i < max_insns; i++, ip++) {
 368                 if (ip->j_format.opcode == j_op)
 369                         return J_TARGET(ip, ip->j_format.target);
 370         }
 371         return 0;
 372 }
 373 #endif
 374
 375 static int __init frame_info_init(void)
 376 {
 377         unsigned long size = 0;
 378 #ifdef CONFIG_KALLSYMS
 379         unsigned long ofs;
 380 #endif
 381         unsigned long addr;
 382
 383         addr = get___schedule_addr();
 384         if (!addr)
 385                 addr = (unsigned long)schedule;
 386
 387 #ifdef CONFIG_KALLSYMS
 388         kallsyms_lookup_size_offset(addr, &size, &ofs);
 389 #endif
 390         schedule_mfi.func = (void *)addr;
 391         schedule_mfi.func_size = size;
 392
 393         get_frame_info(&schedule_mfi);
 394
 395         /*
 396          * Without schedule() frame info, result given by
 397          * thread_saved_pc() and get_wchan() are not reliable.
 398          */
 399         if (schedule_mfi.pc_offset < 0)
 400                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 401
 402         return 0;
 403 }
 404
 405 arch_initcall(frame_info_init);
 406
 407 /*
 408  * Return saved PC of a blocked thread.
 409  */
 410 unsigned long thread_saved_pc(struct task_struct *tsk)
 411 {
 412         struct thread_struct *t = &tsk->thread;
 413
 414         /* New born processes are a special case */
 415         if (t->reg31 == (unsigned long) ret_from_fork)
 416                 return t->reg31;
 417         if (schedule_mfi.pc_offset < 0)
 418                 return 0;
 419         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 420 }
 421
 422
 423 #ifdef CONFIG_KALLSYMS
 424 /* generic stack unwinding function */
 425 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 426                                               unsigned long *sp,
 427                                               unsigned long pc,
 428                                               unsigned long *ra)
 429 {
 430         struct mips_frame_info info;
 431         unsigned long size, ofs;
 432         int leaf;
 433         extern void ret_from_irq(void);
 434         extern void ret_from_exception(void);
 435
 436         if (!stack_page)
 437                 return 0;
 438
 439         /*
 440          * If we reached the bottom of interrupt context,
 441          * return saved pc in pt_regs.
 442          */
 443         if (pc == (unsigned long)ret_from_irq ||
 444             pc == (unsigned long)ret_from_exception) {
 445                 struct pt_regs *regs;
 446                 if (*sp >= stack_page &&
 447                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
 448                         regs = (struct pt_regs *)*sp;
 449                         pc = regs->cp0_epc;
 450                         if (!user_mode(regs) && __kernel_text_address(pc)) {
 451                                 *sp = regs->regs[29];
 452                                 *ra = regs->regs[31];
 453                                 return pc;
 454                         }
 455                 }
 456                 return 0;
 457         }
 458         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 459                 return 0;
 460         /*
 461          * Return ra if an exception occurred at the first instruction
 462          */
 463         if (unlikely(ofs == 0)) {
 464                 pc = *ra;
 465                 *ra = 0;
 466                 return pc;
 467         }
 468
 469         info.func = (void *)(pc - ofs);
 470         info.func_size = ofs;   /* analyze from start to ofs */
 471         leaf = get_frame_info(&info);
 472         if (leaf < 0)
 473                 return 0;
 474
 475         if (*sp < stack_page ||
 476             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
 477                 return 0;
 478
 479         if (leaf)
 480                 /*
 481                  * For some extreme cases, get_frame_info() can
 482                  * consider wrongly a nested function as a leaf
 483                  * one. In that cases avoid to return always the
 484                  * same value.
 485                  */
 486                 pc = pc != *ra ? *ra : 0;
 487         else
 488                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 489
 490         *sp += info.frame_size;
 491         *ra = 0;
 492         return __kernel_text_address(pc) ? pc : 0;
 493 }
 494 EXPORT_SYMBOL(unwind_stack_by_address);
 495
 496 /* used by show_backtrace() */
 497 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 498                            unsigned long pc, unsigned long *ra)
 499 {
 500         unsigned long stack_page = (unsigned long)task_stack_page(task);
 501         return unwind_stack_by_address(stack_page, sp, pc, ra);
 502 }
 503 #endif
 504
 505 /*
 506  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 507  */
 508 unsigned long get_wchan(struct task_struct *task)
 509 {
 510         unsigned long pc = 0;
 511 #ifdef CONFIG_KALLSYMS
 512         unsigned long sp;
 513         unsigned long ra = 0;
 514 #endif
 515
 516         if (!task || task == current || task->state == TASK_RUNNING)
 517                 goto out;
 518         if (!task_stack_page(task))
 519                 goto out;
 520
 521         pc = thread_saved_pc(task);
 522
 523 #ifdef CONFIG_KALLSYMS
 524         sp = task->thread.reg29 + schedule_mfi.frame_size;
 525
 526         while (in_sched_functions(pc))
 527                 pc = unwind_stack(task, &sp, pc, &ra);
 528 #endif
 529
 530 out:
 531         return pc;
 532 }
 533
 534 /*
 535  * Don't forget that the stack pointer must be aligned on a 8 bytes
 536  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 537  */
 538 unsigned long arch_align_stack(unsigned long sp)
 539 {
 540         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 541                 sp -= get_random_int() & ~PAGE_MASK;
 542
 543         return sp & ALMASK;
 544 }
 545
 546 static void arch_dump_stack(void *info)
 547 {
 548         struct pt_regs *regs;
 549
 550         regs = get_irq_regs();
 551
 552         if (regs)
 553                 show_regs(regs);
 554
 555         dump_stack();
 556 }
 557
 558 void arch_trigger_all_cpu_backtrace(bool include_self)
 559 {
 560         smp_call_function(arch_dump_stack, NULL, 1);
 561 }
 562
 563 int mips_get_process_fp_mode(struct task_struct *task)
 564 {
 565         int value = 0;
 566
 567         if (!test_tsk_thread_flag(task, TIF_32BIT_FPREGS))
 568                 value |= PR_FP_MODE_FR;
 569         if (test_tsk_thread_flag(task, TIF_HYBRID_FPREGS))
 570                 value |= PR_FP_MODE_FRE;
 571
 572         return value;
 573 }
 574
 575 static void prepare_for_fp_mode_switch(void *info)
 576 {
 577         struct mm_struct *mm = info;
 578
 579         if (current->mm == mm)
 580                 lose_fpu(1);
 581 }
 582
 583 int mips_set_process_fp_mode(struct task_struct *task, unsigned int value)
 584 {
 585         const unsigned int known_bits = PR_FP_MODE_FR | PR_FP_MODE_FRE;
 586         struct task_struct *t;
 587         int max_users;
 588
 589         /* Check the value is valid */
 590         if (value & ~known_bits)
 591                 return -EOPNOTSUPP;
 592
 593         /* Avoid inadvertently triggering emulation */
 594         if ((value & PR_FP_MODE_FR) && cpu_has_fpu &&
 595             !(current_cpu_data.fpu_id & MIPS_FPIR_F64))
 596                 return -EOPNOTSUPP;
 597         if ((value & PR_FP_MODE_FRE) && cpu_has_fpu && !cpu_has_fre)
 598                 return -EOPNOTSUPP;
 599
 600         /* FR = 0 not supported in MIPS R6 */
 601         if (!(value & PR_FP_MODE_FR) && cpu_has_fpu && cpu_has_mips_r6)
 602                 return -EOPNOTSUPP;
 603
 604         /* Proceed with the mode switch */
 605         preempt_disable();
 606
 607         /* Save FP & vector context, then disable FPU & MSA */
 608         if (task->signal == current->signal)
 609                 lose_fpu(1);
 610
 611         /* Prevent any threads from obtaining live FP context */
 612         atomic_set(&task->mm->context.fp_mode_switching, 1);
 613         smp_mb__after_atomic();
 614
 615         /*
 616          * If there are multiple online CPUs then force any which are running
 617          * threads in this process to lose their FPU context, which they can't
 618          * regain until fp_mode_switching is cleared later.
 619          */
 620         if (num_online_cpus() > 1) {
 621                 /* No need to send an IPI for the local CPU */
 622                 max_users = (task->mm == current->mm) ? 1 : 0;
 623
 624                 if (atomic_read(&current->mm->mm_users) > max_users)
 625                         smp_call_function(prepare_for_fp_mode_switch,
 626                                           (void *)current->mm, 1);
 627         }
 628
 629         /*
 630          * There are now no threads of the process with live FP context, so it
 631          * is safe to proceed with the FP mode switch.
 632          */
 633         for_each_thread(task, t) {
 634                 /* Update desired FP register width */
 635                 if (value & PR_FP_MODE_FR) {
 636                         clear_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 637                 } else {
 638                         set_tsk_thread_flag(t, TIF_32BIT_FPREGS);
 639                         clear_tsk_thread_flag(t, TIF_MSA_CTX_LIVE);
 640                 }
 641
 642                 /* Update desired FP single layout */
 643                 if (value & PR_FP_MODE_FRE)
 644                         set_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 645                 else
 646                         clear_tsk_thread_flag(t, TIF_HYBRID_FPREGS);
 647         }
 648
 649         /* Allow threads to use FP again */
 650         atomic_set(&task->mm->context.fp_mode_switching, 0);
 651         preempt_enable();
 652
 653         return 0;
 654 }