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