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