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 arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  86 {
  87         /*
  88          * Save any process state which is live in hardware registers to the
  89          * parent context prior to duplication. This prevents the new child
  90          * state becoming stale if the parent is preempted before copy_thread()
  91          * gets a chance to save the parent's live hardware registers to the
  92          * child context.
  93          */
  94         preempt_disable();
  95
  96         if (is_msa_enabled())
  97                 save_msa(current);
  98         else if (is_fpu_owner())
  99                 _save_fp(current);
 100
 101         save_dsp(current);
 102
 103         preempt_enable();
 104
 105         *dst = *src;
 106         return 0;
 107 }
 108
 109 int copy_thread(unsigned long clone_flags, unsigned long usp,
 110         unsigned long arg, struct task_struct *p)
 111 {
 112         struct thread_info *ti = task_thread_info(p);
 113         struct pt_regs *childregs, *regs = current_pt_regs();
 114         unsigned long childksp;
 115         p->set_child_tid = p->clear_child_tid = NULL;
 116
 117         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 118
 119         /* set up new TSS. */
 120         childregs = (struct pt_regs *) childksp - 1;
 121         /*  Put the stack after the struct pt_regs.  */
 122         childksp = (unsigned long) childregs;
 123         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 124         if (unlikely(p->flags & PF_KTHREAD)) {
 125                 unsigned long status = p->thread.cp0_status;
 126                 memset(childregs, 0, sizeof(struct pt_regs));
 127                 ti->addr_limit = KERNEL_DS;
 128                 p->thread.reg16 = usp; /* fn */
 129                 p->thread.reg17 = arg;
 130                 p->thread.reg29 = childksp;
 131                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 132 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 133                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 134                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 135 #else
 136                 status |= ST0_EXL;
 137 #endif
 138                 childregs->cp0_status = status;
 139                 return 0;
 140         }
 141         *childregs = *regs;
 142         childregs->regs[7] = 0; /* Clear error flag */
 143         childregs->regs[2] = 0; /* Child gets zero as return value */
 144         if (usp)
 145                 childregs->regs[29] = usp;
 146         ti->addr_limit = USER_DS;
 147
 148         p->thread.reg29 = (unsigned long) childregs;
 149         p->thread.reg31 = (unsigned long) ret_from_fork;
 150
 151         /*
 152          * New tasks lose permission to use the fpu. This accelerates context
 153          * switching for most programs since they don't use the fpu.
 154          */
 155         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 156
 157         clear_tsk_thread_flag(p, TIF_USEDFPU);
 158         clear_tsk_thread_flag(p, TIF_USEDMSA);
 159         clear_tsk_thread_flag(p, TIF_MSA_CTX_LIVE);
 160
 161 #ifdef CONFIG_MIPS_MT_FPAFF
 162         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 163 #endif /* CONFIG_MIPS_MT_FPAFF */
 164
 165         if (clone_flags & CLONE_SETTLS)
 166                 ti->tp_value = regs->regs[7];
 167
 168         return 0;
 169 }
 170
 171 #ifdef CONFIG_CC_STACKPROTECTOR
 172 #include <linux/stackprotector.h>
 173 unsigned long __stack_chk_guard __read_mostly;
 174 EXPORT_SYMBOL(__stack_chk_guard);
 175 #endif
 176
 177 struct mips_frame_info {
 178         void            *func;
 179         unsigned long   func_size;
 180         int             frame_size;
 181         int             pc_offset;
 182 };
 183
 184 #define J_TARGET(pc,target)     \
 185                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 186
 187 static inline int is_ra_save_ins(union mips_instruction *ip)
 188 {
 189 #ifdef CONFIG_CPU_MICROMIPS
 190         union mips_instruction mmi;
 191
 192         /*
 193          * swsp ra,offset
 194          * swm16 reglist,offset(sp)
 195          * swm32 reglist,offset(sp)
 196          * sw32 ra,offset(sp)
 197          * jradiussp - NOT SUPPORTED
 198          *
 199          * microMIPS is way more fun...
 200          */
 201         if (mm_insn_16bit(ip->halfword[0])) {
 202                 mmi.word = (ip->halfword[0] << 16);
 203                 return (mmi.mm16_r5_format.opcode == mm_swsp16_op &&
 204                         mmi.mm16_r5_format.rt == 31) ||
 205                        (mmi.mm16_m_format.opcode == mm_pool16c_op &&
 206                         mmi.mm16_m_format.func == mm_swm16_op);
 207         }
 208         else {
 209                 mmi.halfword[0] = ip->halfword[1];
 210                 mmi.halfword[1] = ip->halfword[0];
 211                 return (mmi.mm_m_format.opcode == mm_pool32b_op &&
 212                         mmi.mm_m_format.rd > 9 &&
 213                         mmi.mm_m_format.base == 29 &&
 214                         mmi.mm_m_format.func == mm_swm32_func) ||
 215                        (mmi.i_format.opcode == mm_sw32_op &&
 216                         mmi.i_format.rs == 29 &&
 217                         mmi.i_format.rt == 31);
 218         }
 219 #else
 220         /* sw / sd $ra, offset($sp) */
 221         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 222                 ip->i_format.rs == 29 &&
 223                 ip->i_format.rt == 31;
 224 #endif
 225 }
 226
 227 static inline int is_jump_ins(union mips_instruction *ip)
 228 {
 229 #ifdef CONFIG_CPU_MICROMIPS
 230         /*
 231          * jr16,jrc,jalr16,jalr16
 232          * jal
 233          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 234          * jraddiusp - NOT SUPPORTED
 235          *
 236          * microMIPS is kind of more fun...
 237          */
 238         union mips_instruction mmi;
 239
 240         mmi.word = (ip->halfword[0] << 16);
 241
 242         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
 243             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
 244             ip->j_format.opcode == mm_jal32_op)
 245                 return 1;
 246         if (ip->r_format.opcode != mm_pool32a_op ||
 247                         ip->r_format.func != mm_pool32axf_op)
 248                 return 0;
 249         return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op;
 250 #else
 251         if (ip->j_format.opcode == j_op)
 252                 return 1;
 253         if (ip->j_format.opcode == jal_op)
 254                 return 1;
 255         if (ip->r_format.opcode != spec_op)
 256                 return 0;
 257         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 258 #endif
 259 }
 260
 261 static inline int is_sp_move_ins(union mips_instruction *ip)
 262 {
 263 #ifdef CONFIG_CPU_MICROMIPS
 264         /*
 265          * addiusp -imm
 266          * addius5 sp,-imm
 267          * addiu32 sp,sp,-imm
 268          * jradiussp - NOT SUPPORTED
 269          *
 270          * microMIPS is not more fun...
 271          */
 272         if (mm_insn_16bit(ip->halfword[0])) {
 273                 union mips_instruction mmi;
 274
 275                 mmi.word = (ip->halfword[0] << 16);
 276                 return (mmi.mm16_r3_format.opcode == mm_pool16d_op &&
 277                         mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
 278                        (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
 279                         mmi.mm16_r5_format.rt == 29);
 280         }
 281         return ip->mm_i_format.opcode == mm_addiu32_op &&
 282                ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29;
 283 #else
 284         /* addiu/daddiu sp,sp,-imm */
 285         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 286                 return 0;
 287         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 288                 return 1;
 289 #endif
 290         return 0;
 291 }
 292
 293 static int get_frame_info(struct mips_frame_info *info)
 294 {
 295 #ifdef CONFIG_CPU_MICROMIPS
 296         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
 297 #else
 298         union mips_instruction *ip = info->func;
 299 #endif
 300         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 301         unsigned i;
 302
 303         info->pc_offset = -1;
 304         info->frame_size = 0;
 305
 306         if (!ip)
 307                 goto err;
 308
 309         if (max_insns == 0)
 310                 max_insns = 128U;       /* unknown function size */
 311         max_insns = min(128U, max_insns);
 312
 313         for (i = 0; i < max_insns; i++, ip++) {
 314
 315                 if (is_jump_ins(ip))
 316                         break;
 317                 if (!info->frame_size) {
 318                         if (is_sp_move_ins(ip))
 319                         {
 320 #ifdef CONFIG_CPU_MICROMIPS
 321                                 if (mm_insn_16bit(ip->halfword[0]))
 322                                 {
 323                                         unsigned short tmp;
 324
 325                                         if (ip->halfword[0] & mm_addiusp_func)
 326                                         {
 327                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 328                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 329                                         } else {
 330                                                 tmp = (ip->halfword[0] >> 1);
 331                                                 info->frame_size = -(signed short)(tmp & 0xf);
 332                                         }
 333                                         ip = (void *) &ip->halfword[1];
 334                                         ip--;
 335                                 } else
 336 #endif
 337                                 info->frame_size = - ip->i_format.simmediate;
 338                         }
 339                         continue;
 340                 }
 341                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
 342                         info->pc_offset =
 343                                 ip->i_format.simmediate / sizeof(long);
 344                         break;
 345                 }
 346         }
 347         if (info->frame_size && info->pc_offset >= 0) /* nested */
 348                 return 0;
 349         if (info->pc_offset < 0) /* leaf */
 350                 return 1;
 351         /* prologue seems boggus... */
 352 err:
 353         return -1;
 354 }
 355
 356 static struct mips_frame_info schedule_mfi __read_mostly;
 357
 358 #ifdef CONFIG_KALLSYMS
 359 static unsigned long get___schedule_addr(void)
 360 {
 361         return kallsyms_lookup_name("__schedule");
 362 }
 363 #else
 364 static unsigned long get___schedule_addr(void)
 365 {
 366         union mips_instruction *ip = (void *)schedule;
 367         int max_insns = 8;
 368         int i;
 369
 370         for (i = 0; i < max_insns; i++, ip++) {
 371                 if (ip->j_format.opcode == j_op)
 372                         return J_TARGET(ip, ip->j_format.target);
 373         }
 374         return 0;
 375 }
 376 #endif
 377
 378 static int __init frame_info_init(void)
 379 {
 380         unsigned long size = 0;
 381 #ifdef CONFIG_KALLSYMS
 382         unsigned long ofs;
 383 #endif
 384         unsigned long addr;
 385
 386         addr = get___schedule_addr();
 387         if (!addr)
 388                 addr = (unsigned long)schedule;
 389
 390 #ifdef CONFIG_KALLSYMS
 391         kallsyms_lookup_size_offset(addr, &size, &ofs);
 392 #endif
 393         schedule_mfi.func = (void *)addr;
 394         schedule_mfi.func_size = size;
 395
 396         get_frame_info(&schedule_mfi);
 397
 398         /*
 399          * Without schedule() frame info, result given by
 400          * thread_saved_pc() and get_wchan() are not reliable.
 401          */
 402         if (schedule_mfi.pc_offset < 0)
 403                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 404
 405         return 0;
 406 }
 407
 408 arch_initcall(frame_info_init);
 409
 410 /*
 411  * Return saved PC of a blocked thread.
 412  */
 413 unsigned long thread_saved_pc(struct task_struct *tsk)
 414 {
 415         struct thread_struct *t = &tsk->thread;
 416
 417         /* New born processes are a special case */
 418         if (t->reg31 == (unsigned long) ret_from_fork)
 419                 return t->reg31;
 420         if (schedule_mfi.pc_offset < 0)
 421                 return 0;
 422         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 423 }
 424
 425
 426 #ifdef CONFIG_KALLSYMS
 427 /* generic stack unwinding function */
 428 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 429                                               unsigned long *sp,
 430                                               unsigned long pc,
 431                                               unsigned long *ra)
 432 {
 433         struct mips_frame_info info;
 434         unsigned long size, ofs;
 435         int leaf;
 436         extern void ret_from_irq(void);
 437         extern void ret_from_exception(void);
 438
 439         if (!stack_page)
 440                 return 0;
 441
 442         /*
 443          * If we reached the bottom of interrupt context,
 444          * return saved pc in pt_regs.
 445          */
 446         if (pc == (unsigned long)ret_from_irq ||
 447             pc == (unsigned long)ret_from_exception) {
 448                 struct pt_regs *regs;
 449                 if (*sp >= stack_page &&
 450                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
 451                         regs = (struct pt_regs *)*sp;
 452                         pc = regs->cp0_epc;
 453                         if (__kernel_text_address(pc)) {
 454                                 *sp = regs->regs[29];
 455                                 *ra = regs->regs[31];
 456                                 return pc;
 457                         }
 458                 }
 459                 return 0;
 460         }
 461         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 462                 return 0;
 463         /*
 464          * Return ra if an exception occurred at the first instruction
 465          */
 466         if (unlikely(ofs == 0)) {
 467                 pc = *ra;
 468                 *ra = 0;
 469                 return pc;
 470         }
 471
 472         info.func = (void *)(pc - ofs);
 473         info.func_size = ofs;   /* analyze from start to ofs */
 474         leaf = get_frame_info(&info);
 475         if (leaf < 0)
 476                 return 0;
 477
 478         if (*sp < stack_page ||
 479             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
 480                 return 0;
 481
 482         if (leaf)
 483                 /*
 484                  * For some extreme cases, get_frame_info() can
 485                  * consider wrongly a nested function as a leaf
 486                  * one. In that cases avoid to return always the
 487                  * same value.
 488                  */
 489                 pc = pc != *ra ? *ra : 0;
 490         else
 491                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 492
 493         *sp += info.frame_size;
 494         *ra = 0;
 495         return __kernel_text_address(pc) ? pc : 0;
 496 }
 497 EXPORT_SYMBOL(unwind_stack_by_address);
 498
 499 /* used by show_backtrace() */
 500 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 501                            unsigned long pc, unsigned long *ra)
 502 {
 503         unsigned long stack_page = (unsigned long)task_stack_page(task);
 504         return unwind_stack_by_address(stack_page, sp, pc, ra);
 505 }
 506 #endif
 507
 508 /*
 509  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 510  */
 511 unsigned long get_wchan(struct task_struct *task)
 512 {
 513         unsigned long pc = 0;
 514 #ifdef CONFIG_KALLSYMS
 515         unsigned long sp;
 516         unsigned long ra = 0;
 517 #endif
 518
 519         if (!task || task == current || task->state == TASK_RUNNING)
 520                 goto out;
 521         if (!task_stack_page(task))
 522                 goto out;
 523
 524         pc = thread_saved_pc(task);
 525
 526 #ifdef CONFIG_KALLSYMS
 527         sp = task->thread.reg29 + schedule_mfi.frame_size;
 528
 529         while (in_sched_functions(pc))
 530                 pc = unwind_stack(task, &sp, pc, &ra);
 531 #endif
 532
 533 out:
 534         return pc;
 535 }
 536
 537 /*
 538  * Don't forget that the stack pointer must be aligned on a 8 bytes
 539  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 540  */
 541 unsigned long arch_align_stack(unsigned long sp)
 542 {
 543         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 544                 sp -= get_random_int() & ~PAGE_MASK;
 545
 546         return sp & ALMASK;
 547 }
 548
 549 static void arch_dump_stack(void *info)
 550 {
 551         struct pt_regs *regs;
 552
 553         regs = get_irq_regs();
 554
 555         if (regs)
 556                 show_regs(regs);
 557
 558         dump_stack();
 559 }
 560
 561 void arch_trigger_all_cpu_backtrace(bool include_self)
 562 {
 563         smp_call_function(arch_dump_stack, NULL, 1);
 564 }