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/pgtable.h>
  36 #include <asm/mipsregs.h>
  37 #include <asm/processor.h>
  38 #include <asm/uaccess.h>
  39 #include <asm/io.h>
  40 #include <asm/elf.h>
  41 #include <asm/isadep.h>
  42 #include <asm/inst.h>
  43 #include <asm/stacktrace.h>
  44
  45 #ifdef CONFIG_HOTPLUG_CPU
  46 void arch_cpu_idle_dead(void)
  47 {
  48         /* What the heck is this check doing ? */
  49         if (!cpu_isset(smp_processor_id(), cpu_callin_map))
  50                 play_dead();
  51 }
  52 #endif
  53
  54 void arch_cpu_idle(void)
  55 {
  56 #ifdef CONFIG_MIPS_MT_SMTC
  57         extern void smtc_idle_loop_hook(void);
  58
  59         smtc_idle_loop_hook();
  60 #endif
  61         if (cpu_wait)
  62                 (*cpu_wait)();
  63         else
  64                 local_irq_enable();
  65 }
  66
  67 asmlinkage void ret_from_fork(void);
  68 asmlinkage void ret_from_kernel_thread(void);
  69
  70 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  71 {
  72         unsigned long status;
  73
  74         /* New thread loses kernel privileges. */
  75         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
  76 #ifdef CONFIG_64BIT
  77         status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
  78 #endif
  79         status |= KU_USER;
  80         regs->cp0_status = status;
  81         clear_used_math();
  82         clear_fpu_owner();
  83         if (cpu_has_dsp)
  84                 __init_dsp();
  85         regs->cp0_epc = pc;
  86         regs->regs[29] = sp;
  87 }
  88
  89 void exit_thread(void)
  90 {
  91 }
  92
  93 void flush_thread(void)
  94 {
  95 }
  96
  97 int copy_thread(unsigned long clone_flags, unsigned long usp,
  98         unsigned long arg, struct task_struct *p)
  99 {
 100         struct thread_info *ti = task_thread_info(p);
 101         struct pt_regs *childregs, *regs = current_pt_regs();
 102         unsigned long childksp;
 103         p->set_child_tid = p->clear_child_tid = NULL;
 104
 105         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 106
 107         preempt_disable();
 108
 109         if (is_fpu_owner())
 110                 save_fp(p);
 111
 112         if (cpu_has_dsp)
 113                 save_dsp(p);
 114
 115         preempt_enable();
 116
 117         /* set up new TSS. */
 118         childregs = (struct pt_regs *) childksp - 1;
 119         /*  Put the stack after the struct pt_regs.  */
 120         childksp = (unsigned long) childregs;
 121         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 122         if (unlikely(p->flags & PF_KTHREAD)) {
 123                 unsigned long status = p->thread.cp0_status;
 124                 memset(childregs, 0, sizeof(struct pt_regs));
 125                 ti->addr_limit = KERNEL_DS;
 126                 p->thread.reg16 = usp; /* fn */
 127                 p->thread.reg17 = arg;
 128                 p->thread.reg29 = childksp;
 129                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 130 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 131                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 132                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 133 #else
 134                 status |= ST0_EXL;
 135 #endif
 136                 childregs->cp0_status = status;
 137                 return 0;
 138         }
 139         *childregs = *regs;
 140         childregs->regs[7] = 0; /* Clear error flag */
 141         childregs->regs[2] = 0; /* Child gets zero as return value */
 142         if (usp)
 143                 childregs->regs[29] = usp;
 144         ti->addr_limit = USER_DS;
 145
 146         p->thread.reg29 = (unsigned long) childregs;
 147         p->thread.reg31 = (unsigned long) ret_from_fork;
 148
 149         /*
 150          * New tasks lose permission to use the fpu. This accelerates context
 151          * switching for most programs since they don't use the fpu.
 152          */
 153         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 154
 155 #ifdef CONFIG_MIPS_MT_SMTC
 156         /*
 157          * SMTC restores TCStatus after Status, and the CU bits
 158          * are aliased there.
 159          */
 160         childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
 161 #endif
 162         clear_tsk_thread_flag(p, TIF_USEDFPU);
 163
 164 #ifdef CONFIG_MIPS_MT_FPAFF
 165         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 166 #endif /* CONFIG_MIPS_MT_FPAFF */
 167
 168         if (clone_flags & CLONE_SETTLS)
 169                 ti->tp_value = regs->regs[7];
 170
 171         return 0;
 172 }
 173
 174 /* Fill in the fpu structure for a core dump.. */
 175 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 176 {
 177         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
 178
 179         return 1;
 180 }
 181
 182 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
 183 {
 184         int i;
 185
 186         for (i = 0; i < EF_R0; i++)
 187                 gp[i] = 0;
 188         gp[EF_R0] = 0;
 189         for (i = 1; i <= 31; i++)
 190                 gp[EF_R0 + i] = regs->regs[i];
 191         gp[EF_R26] = 0;
 192         gp[EF_R27] = 0;
 193         gp[EF_LO] = regs->lo;
 194         gp[EF_HI] = regs->hi;
 195         gp[EF_CP0_EPC] = regs->cp0_epc;
 196         gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 197         gp[EF_CP0_STATUS] = regs->cp0_status;
 198         gp[EF_CP0_CAUSE] = regs->cp0_cause;
 199 #ifdef EF_UNUSED0
 200         gp[EF_UNUSED0] = 0;
 201 #endif
 202 }
 203
 204 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 205 {
 206         elf_dump_regs(*regs, task_pt_regs(tsk));
 207         return 1;
 208 }
 209
 210 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
 211 {
 212         memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
 213
 214         return 1;
 215 }
 216
 217 /*
 218  *
 219  */
 220 struct mips_frame_info {
 221         void            *func;
 222         unsigned long   func_size;
 223         int             frame_size;
 224         int             pc_offset;
 225 };
 226
 227 static inline int is_ra_save_ins(union mips_instruction *ip)
 228 {
 229 #ifdef CONFIG_CPU_MICROMIPS
 230         union mips_instruction mmi;
 231
 232         /*
 233          * swsp ra,offset
 234          * swm16 reglist,offset(sp)
 235          * swm32 reglist,offset(sp)
 236          * sw32 ra,offset(sp)
 237          * jradiussp - NOT SUPPORTED
 238          *
 239          * microMIPS is way more fun...
 240          */
 241         if (mm_insn_16bit(ip->halfword[0])) {
 242                 mmi.word = (ip->halfword[0] << 16);
 243                 return ((mmi.mm16_r5_format.opcode == mm_swsp16_op &&
 244                          mmi.mm16_r5_format.rt == 31) ||
 245                         (mmi.mm16_m_format.opcode == mm_pool16c_op &&
 246                          mmi.mm16_m_format.func == mm_swm16_op));
 247         }
 248         else {
 249                 mmi.halfword[0] = ip->halfword[1];
 250                 mmi.halfword[1] = ip->halfword[0];
 251                 return ((mmi.mm_m_format.opcode == mm_pool32b_op &&
 252                          mmi.mm_m_format.rd > 9 &&
 253                          mmi.mm_m_format.base == 29 &&
 254                          mmi.mm_m_format.func == mm_swm32_func) ||
 255                         (mmi.i_format.opcode == mm_sw32_op &&
 256                          mmi.i_format.rs == 29 &&
 257                          mmi.i_format.rt == 31));
 258         }
 259 #else
 260         /* sw / sd $ra, offset($sp) */
 261         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 262                 ip->i_format.rs == 29 &&
 263                 ip->i_format.rt == 31;
 264 #endif
 265 }
 266
 267 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
 268 {
 269 #ifdef CONFIG_CPU_MICROMIPS
 270         /*
 271          * jr16,jrc,jalr16,jalr16
 272          * jal
 273          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 274          * jraddiusp - NOT SUPPORTED
 275          *
 276          * microMIPS is kind of more fun...
 277          */
 278         union mips_instruction mmi;
 279
 280         mmi.word = (ip->halfword[0] << 16);
 281
 282         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
 283             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
 284             ip->j_format.opcode == mm_jal32_op)
 285                 return 1;
 286         if (ip->r_format.opcode != mm_pool32a_op ||
 287                         ip->r_format.func != mm_pool32axf_op)
 288                 return 0;
 289         return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
 290 #else
 291         if (ip->j_format.opcode == jal_op)
 292                 return 1;
 293         if (ip->r_format.opcode != spec_op)
 294                 return 0;
 295         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 296 #endif
 297 }
 298
 299 static inline int is_sp_move_ins(union mips_instruction *ip)
 300 {
 301 #ifdef CONFIG_CPU_MICROMIPS
 302         /*
 303          * addiusp -imm
 304          * addius5 sp,-imm
 305          * addiu32 sp,sp,-imm
 306          * jradiussp - NOT SUPPORTED
 307          *
 308          * microMIPS is not more fun...
 309          */
 310         if (mm_insn_16bit(ip->halfword[0])) {
 311                 union mips_instruction mmi;
 312
 313                 mmi.word = (ip->halfword[0] << 16);
 314                 return ((mmi.mm16_r3_format.opcode == mm_pool16d_op &&
 315                          mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
 316                         (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
 317                          mmi.mm16_r5_format.rt == 29));
 318         }
 319         return (ip->mm_i_format.opcode == mm_addiu32_op &&
 320                  ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29);
 321 #else
 322         /* addiu/daddiu sp,sp,-imm */
 323         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 324                 return 0;
 325         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 326                 return 1;
 327 #endif
 328         return 0;
 329 }
 330
 331 static int get_frame_info(struct mips_frame_info *info)
 332 {
 333 #ifdef CONFIG_CPU_MICROMIPS
 334         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
 335 #else
 336         union mips_instruction *ip = info->func;
 337 #endif
 338         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 339         unsigned i;
 340
 341         info->pc_offset = -1;
 342         info->frame_size = 0;
 343
 344         if (!ip)
 345                 goto err;
 346
 347         if (max_insns == 0)
 348                 max_insns = 128U;       /* unknown function size */
 349         max_insns = min(128U, max_insns);
 350
 351         for (i = 0; i < max_insns; i++, ip++) {
 352
 353                 if (is_jal_jalr_jr_ins(ip))
 354                         break;
 355                 if (!info->frame_size) {
 356                         if (is_sp_move_ins(ip))
 357                         {
 358 #ifdef CONFIG_CPU_MICROMIPS
 359                                 if (mm_insn_16bit(ip->halfword[0]))
 360                                 {
 361                                         unsigned short tmp;
 362
 363                                         if (ip->halfword[0] & mm_addiusp_func)
 364                                         {
 365                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 366                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 367                                         } else {
 368                                                 tmp = (ip->halfword[0] >> 1);
 369                                                 info->frame_size = -(signed short)(tmp & 0xf);
 370                                         }
 371                                         ip = (void *) &ip->halfword[1];
 372                                         ip--;
 373                                 } else
 374 #endif
 375                                 info->frame_size = - ip->i_format.simmediate;
 376                         }
 377                         continue;
 378                 }
 379                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
 380                         info->pc_offset =
 381                                 ip->i_format.simmediate / sizeof(long);
 382                         break;
 383                 }
 384         }
 385         if (info->frame_size && info->pc_offset >= 0) /* nested */
 386                 return 0;
 387         if (info->pc_offset < 0) /* leaf */
 388                 return 1;
 389         /* prologue seems boggus... */
 390 err:
 391         return -1;
 392 }
 393
 394 static struct mips_frame_info schedule_mfi __read_mostly;
 395
 396 static int __init frame_info_init(void)
 397 {
 398         unsigned long size = 0;
 399 #ifdef CONFIG_KALLSYMS
 400         unsigned long ofs;
 401
 402         kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);
 403 #endif
 404         schedule_mfi.func = schedule;
 405         schedule_mfi.func_size = size;
 406
 407         get_frame_info(&schedule_mfi);
 408
 409         /*
 410          * Without schedule() frame info, result given by
 411          * thread_saved_pc() and get_wchan() are not reliable.
 412          */
 413         if (schedule_mfi.pc_offset < 0)
 414                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 415
 416         return 0;
 417 }
 418
 419 arch_initcall(frame_info_init);
 420
 421 /*
 422  * Return saved PC of a blocked thread.
 423  */
 424 unsigned long thread_saved_pc(struct task_struct *tsk)
 425 {
 426         struct thread_struct *t = &tsk->thread;
 427
 428         /* New born processes are a special case */
 429         if (t->reg31 == (unsigned long) ret_from_fork)
 430                 return t->reg31;
 431         if (schedule_mfi.pc_offset < 0)
 432                 return 0;
 433         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 434 }
 435
 436
 437 #ifdef CONFIG_KALLSYMS
 438 /* generic stack unwinding function */
 439 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 440                                               unsigned long *sp,
 441                                               unsigned long pc,
 442                                               unsigned long *ra)
 443 {
 444         struct mips_frame_info info;
 445         unsigned long size, ofs;
 446         int leaf;
 447         extern void ret_from_irq(void);
 448         extern void ret_from_exception(void);
 449
 450         if (!stack_page)
 451                 return 0;
 452
 453         /*
 454          * If we reached the bottom of interrupt context,
 455          * return saved pc in pt_regs.
 456          */
 457         if (pc == (unsigned long)ret_from_irq ||
 458             pc == (unsigned long)ret_from_exception) {
 459                 struct pt_regs *regs;
 460                 if (*sp >= stack_page &&
 461                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
 462                         regs = (struct pt_regs *)*sp;
 463                         pc = regs->cp0_epc;
 464                         if (__kernel_text_address(pc)) {
 465                                 *sp = regs->regs[29];
 466                                 *ra = regs->regs[31];
 467                                 return pc;
 468                         }
 469                 }
 470                 return 0;
 471         }
 472         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 473                 return 0;
 474         /*
 475          * Return ra if an exception occurred at the first instruction
 476          */
 477         if (unlikely(ofs == 0)) {
 478                 pc = *ra;
 479                 *ra = 0;
 480                 return pc;
 481         }
 482
 483         info.func = (void *)(pc - ofs);
 484         info.func_size = ofs;   /* analyze from start to ofs */
 485         leaf = get_frame_info(&info);
 486         if (leaf < 0)
 487                 return 0;
 488
 489         if (*sp < stack_page ||
 490             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
 491                 return 0;
 492
 493         if (leaf)
 494                 /*
 495                  * For some extreme cases, get_frame_info() can
 496                  * consider wrongly a nested function as a leaf
 497                  * one. In that cases avoid to return always the
 498                  * same value.
 499                  */
 500                 pc = pc != *ra ? *ra : 0;
 501         else
 502                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 503
 504         *sp += info.frame_size;
 505         *ra = 0;
 506         return __kernel_text_address(pc) ? pc : 0;
 507 }
 508 EXPORT_SYMBOL(unwind_stack_by_address);
 509
 510 /* used by show_backtrace() */
 511 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 512                            unsigned long pc, unsigned long *ra)
 513 {
 514         unsigned long stack_page = (unsigned long)task_stack_page(task);
 515         return unwind_stack_by_address(stack_page, sp, pc, ra);
 516 }
 517 #endif
 518
 519 /*
 520  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 521  */
 522 unsigned long get_wchan(struct task_struct *task)
 523 {
 524         unsigned long pc = 0;
 525 #ifdef CONFIG_KALLSYMS
 526         unsigned long sp;
 527         unsigned long ra = 0;
 528 #endif
 529
 530         if (!task || task == current || task->state == TASK_RUNNING)
 531                 goto out;
 532         if (!task_stack_page(task))
 533                 goto out;
 534
 535         pc = thread_saved_pc(task);
 536
 537 #ifdef CONFIG_KALLSYMS
 538         sp = task->thread.reg29 + schedule_mfi.frame_size;
 539
 540         while (in_sched_functions(pc))
 541                 pc = unwind_stack(task, &sp, pc, &ra);
 542 #endif
 543
 544 out:
 545         return pc;
 546 }
 547
 548 /*
 549  * Don't forget that the stack pointer must be aligned on a 8 bytes
 550  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 551  */
 552 unsigned long arch_align_stack(unsigned long sp)
 553 {
 554         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 555                 sp -= get_random_int() & ~PAGE_MASK;
 556
 557         return sp & ALMASK;
 558 }