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