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