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 #ifdef CONFIG_MIPS_MT_SMTC
 144         /*
 145          * SMTC restores TCStatus after Status, and the CU bits
 146          * are aliased there.
 147          */
 148         childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
 149 #endif
 150         clear_tsk_thread_flag(p, TIF_USEDFPU);
 151
 152 #ifdef CONFIG_MIPS_MT_FPAFF
 153         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 154 #endif /* CONFIG_MIPS_MT_FPAFF */
 155
 156         if (clone_flags & CLONE_SETTLS)
 157                 ti->tp_value = regs->regs[7];
 158
 159         return 0;
 160 }
 161
 162 /* Fill in the fpu structure for a core dump.. */
 163 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 164 {
 165         int i;
 166
 167         for (i = 0; i < NUM_FPU_REGS; i++)
 168                 memcpy(&r[i], &current->thread.fpu.fpr[i], sizeof(*r));
 169
 170         memcpy(&r[NUM_FPU_REGS], &current->thread.fpu.fcr31,
 171                sizeof(current->thread.fpu.fcr31));
 172
 173         return 1;
 174 }
 175
 176 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
 177 {
 178         int i;
 179
 180         for (i = 0; i < EF_R0; i++)
 181                 gp[i] = 0;
 182         gp[EF_R0] = 0;
 183         for (i = 1; i <= 31; i++)
 184                 gp[EF_R0 + i] = regs->regs[i];
 185         gp[EF_R26] = 0;
 186         gp[EF_R27] = 0;
 187         gp[EF_LO] = regs->lo;
 188         gp[EF_HI] = regs->hi;
 189         gp[EF_CP0_EPC] = regs->cp0_epc;
 190         gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 191         gp[EF_CP0_STATUS] = regs->cp0_status;
 192         gp[EF_CP0_CAUSE] = regs->cp0_cause;
 193 #ifdef EF_UNUSED0
 194         gp[EF_UNUSED0] = 0;
 195 #endif
 196 }
 197
 198 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 199 {
 200         elf_dump_regs(*regs, task_pt_regs(tsk));
 201         return 1;
 202 }
 203
 204 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
 205 {
 206         int i;
 207
 208         for (i = 0; i < NUM_FPU_REGS; i++)
 209                 memcpy(&fpr[i], &t->thread.fpu.fpr[i], sizeof(*fpr));
 210
 211         memcpy(&fpr[NUM_FPU_REGS], &t->thread.fpu.fcr31,
 212                sizeof(t->thread.fpu.fcr31));
 213
 214         return 1;
 215 }
 216
 217 #ifdef CONFIG_CC_STACKPROTECTOR
 218 #include <linux/stackprotector.h>
 219 unsigned long __stack_chk_guard __read_mostly;
 220 EXPORT_SYMBOL(__stack_chk_guard);
 221 #endif
 222
 223 struct mips_frame_info {
 224         void            *func;
 225         unsigned long   func_size;
 226         int             frame_size;
 227         int             pc_offset;
 228 };
 229
 230 #define J_TARGET(pc,target)     \
 231                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 232
 233 static inline int is_ra_save_ins(union mips_instruction *ip)
 234 {
 235 #ifdef CONFIG_CPU_MICROMIPS
 236         union mips_instruction mmi;
 237
 238         /*
 239          * swsp ra,offset
 240          * swm16 reglist,offset(sp)
 241          * swm32 reglist,offset(sp)
 242          * sw32 ra,offset(sp)
 243          * jradiussp - NOT SUPPORTED
 244          *
 245          * microMIPS is way more fun...
 246          */
 247         if (mm_insn_16bit(ip->halfword[0])) {
 248                 mmi.word = (ip->halfword[0] << 16);
 249                 return ((mmi.mm16_r5_format.opcode == mm_swsp16_op &&
 250                          mmi.mm16_r5_format.rt == 31) ||
 251                         (mmi.mm16_m_format.opcode == mm_pool16c_op &&
 252                          mmi.mm16_m_format.func == mm_swm16_op));
 253         }
 254         else {
 255                 mmi.halfword[0] = ip->halfword[1];
 256                 mmi.halfword[1] = ip->halfword[0];
 257                 return ((mmi.mm_m_format.opcode == mm_pool32b_op &&
 258                          mmi.mm_m_format.rd > 9 &&
 259                          mmi.mm_m_format.base == 29 &&
 260                          mmi.mm_m_format.func == mm_swm32_func) ||
 261                         (mmi.i_format.opcode == mm_sw32_op &&
 262                          mmi.i_format.rs == 29 &&
 263                          mmi.i_format.rt == 31));
 264         }
 265 #else
 266         /* sw / sd $ra, offset($sp) */
 267         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 268                 ip->i_format.rs == 29 &&
 269                 ip->i_format.rt == 31;
 270 #endif
 271 }
 272
 273 static inline int is_jump_ins(union mips_instruction *ip)
 274 {
 275 #ifdef CONFIG_CPU_MICROMIPS
 276         /*
 277          * jr16,jrc,jalr16,jalr16
 278          * jal
 279          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 280          * jraddiusp - NOT SUPPORTED
 281          *
 282          * microMIPS is kind of more fun...
 283          */
 284         union mips_instruction mmi;
 285
 286         mmi.word = (ip->halfword[0] << 16);
 287
 288         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
 289             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
 290             ip->j_format.opcode == mm_jal32_op)
 291                 return 1;
 292         if (ip->r_format.opcode != mm_pool32a_op ||
 293                         ip->r_format.func != mm_pool32axf_op)
 294                 return 0;
 295         return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
 296 #else
 297         if (ip->j_format.opcode == j_op)
 298                 return 1;
 299         if (ip->j_format.opcode == jal_op)
 300                 return 1;
 301         if (ip->r_format.opcode != spec_op)
 302                 return 0;
 303         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 304 #endif
 305 }
 306
 307 static inline int is_sp_move_ins(union mips_instruction *ip)
 308 {
 309 #ifdef CONFIG_CPU_MICROMIPS
 310         /*
 311          * addiusp -imm
 312          * addius5 sp,-imm
 313          * addiu32 sp,sp,-imm
 314          * jradiussp - NOT SUPPORTED
 315          *
 316          * microMIPS is not more fun...
 317          */
 318         if (mm_insn_16bit(ip->halfword[0])) {
 319                 union mips_instruction mmi;
 320
 321                 mmi.word = (ip->halfword[0] << 16);
 322                 return ((mmi.mm16_r3_format.opcode == mm_pool16d_op &&
 323                          mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
 324                         (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
 325                          mmi.mm16_r5_format.rt == 29));
 326         }
 327         return (ip->mm_i_format.opcode == mm_addiu32_op &&
 328                  ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29);
 329 #else
 330         /* addiu/daddiu sp,sp,-imm */
 331         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 332                 return 0;
 333         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 334                 return 1;
 335 #endif
 336         return 0;
 337 }
 338
 339 static int get_frame_info(struct mips_frame_info *info)
 340 {
 341 #ifdef CONFIG_CPU_MICROMIPS
 342         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
 343 #else
 344         union mips_instruction *ip = info->func;
 345 #endif
 346         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 347         unsigned i;
 348
 349         info->pc_offset = -1;
 350         info->frame_size = 0;
 351
 352         if (!ip)
 353                 goto err;
 354
 355         if (max_insns == 0)
 356                 max_insns = 128U;       /* unknown function size */
 357         max_insns = min(128U, max_insns);
 358
 359         for (i = 0; i < max_insns; i++, ip++) {
 360
 361                 if (is_jump_ins(ip))
 362                         break;
 363                 if (!info->frame_size) {
 364                         if (is_sp_move_ins(ip))
 365                         {
 366 #ifdef CONFIG_CPU_MICROMIPS
 367                                 if (mm_insn_16bit(ip->halfword[0]))
 368                                 {
 369                                         unsigned short tmp;
 370
 371                                         if (ip->halfword[0] & mm_addiusp_func)
 372                                         {
 373                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 374                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 375                                         } else {
 376                                                 tmp = (ip->halfword[0] >> 1);
 377                                                 info->frame_size = -(signed short)(tmp & 0xf);
 378                                         }
 379                                         ip = (void *) &ip->halfword[1];
 380                                         ip--;
 381                                 } else
 382 #endif
 383                                 info->frame_size = - ip->i_format.simmediate;
 384                         }
 385                         continue;
 386                 }
 387                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
 388                         info->pc_offset =
 389                                 ip->i_format.simmediate / sizeof(long);
 390                         break;
 391                 }
 392         }
 393         if (info->frame_size && info->pc_offset >= 0) /* nested */
 394                 return 0;
 395         if (info->pc_offset < 0) /* leaf */
 396                 return 1;
 397         /* prologue seems boggus... */
 398 err:
 399         return -1;
 400 }
 401
 402 static struct mips_frame_info schedule_mfi __read_mostly;
 403
 404 #ifdef CONFIG_KALLSYMS
 405 static unsigned long get___schedule_addr(void)
 406 {
 407         return kallsyms_lookup_name("__schedule");
 408 }
 409 #else
 410 static unsigned long get___schedule_addr(void)
 411 {
 412         union mips_instruction *ip = (void *)schedule;
 413         int max_insns = 8;
 414         int i;
 415
 416         for (i = 0; i < max_insns; i++, ip++) {
 417                 if (ip->j_format.opcode == j_op)
 418                         return J_TARGET(ip, ip->j_format.target);
 419         }
 420         return 0;
 421 }
 422 #endif
 423
 424 static int __init frame_info_init(void)
 425 {
 426         unsigned long size = 0;
 427 #ifdef CONFIG_KALLSYMS
 428         unsigned long ofs;
 429 #endif
 430         unsigned long addr;
 431
 432         addr = get___schedule_addr();
 433         if (!addr)
 434                 addr = (unsigned long)schedule;
 435
 436 #ifdef CONFIG_KALLSYMS
 437         kallsyms_lookup_size_offset(addr, &size, &ofs);
 438 #endif
 439         schedule_mfi.func = (void *)addr;
 440         schedule_mfi.func_size = size;
 441
 442         get_frame_info(&schedule_mfi);
 443
 444         /*
 445          * Without schedule() frame info, result given by
 446          * thread_saved_pc() and get_wchan() are not reliable.
 447          */
 448         if (schedule_mfi.pc_offset < 0)
 449                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 450
 451         return 0;
 452 }
 453
 454 arch_initcall(frame_info_init);
 455
 456 /*
 457  * Return saved PC of a blocked thread.
 458  */
 459 unsigned long thread_saved_pc(struct task_struct *tsk)
 460 {
 461         struct thread_struct *t = &tsk->thread;
 462
 463         /* New born processes are a special case */
 464         if (t->reg31 == (unsigned long) ret_from_fork)
 465                 return t->reg31;
 466         if (schedule_mfi.pc_offset < 0)
 467                 return 0;
 468         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 469 }
 470
 471
 472 #ifdef CONFIG_KALLSYMS
 473 /* generic stack unwinding function */
 474 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 475                                               unsigned long *sp,
 476                                               unsigned long pc,
 477                                               unsigned long *ra)
 478 {
 479         struct mips_frame_info info;
 480         unsigned long size, ofs;
 481         int leaf;
 482         extern void ret_from_irq(void);
 483         extern void ret_from_exception(void);
 484
 485         if (!stack_page)
 486                 return 0;
 487
 488         /*
 489          * If we reached the bottom of interrupt context,
 490          * return saved pc in pt_regs.
 491          */
 492         if (pc == (unsigned long)ret_from_irq ||
 493             pc == (unsigned long)ret_from_exception) {
 494                 struct pt_regs *regs;
 495                 if (*sp >= stack_page &&
 496                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
 497                         regs = (struct pt_regs *)*sp;
 498                         pc = regs->cp0_epc;
 499                         if (__kernel_text_address(pc)) {
 500                                 *sp = regs->regs[29];
 501                                 *ra = regs->regs[31];
 502                                 return pc;
 503                         }
 504                 }
 505                 return 0;
 506         }
 507         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 508                 return 0;
 509         /*
 510          * Return ra if an exception occurred at the first instruction
 511          */
 512         if (unlikely(ofs == 0)) {
 513                 pc = *ra;
 514                 *ra = 0;
 515                 return pc;
 516         }
 517
 518         info.func = (void *)(pc - ofs);
 519         info.func_size = ofs;   /* analyze from start to ofs */
 520         leaf = get_frame_info(&info);
 521         if (leaf < 0)
 522                 return 0;
 523
 524         if (*sp < stack_page ||
 525             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
 526                 return 0;
 527
 528         if (leaf)
 529                 /*
 530                  * For some extreme cases, get_frame_info() can
 531                  * consider wrongly a nested function as a leaf
 532                  * one. In that cases avoid to return always the
 533                  * same value.
 534                  */
 535                 pc = pc != *ra ? *ra : 0;
 536         else
 537                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 538
 539         *sp += info.frame_size;
 540         *ra = 0;
 541         return __kernel_text_address(pc) ? pc : 0;
 542 }
 543 EXPORT_SYMBOL(unwind_stack_by_address);
 544
 545 /* used by show_backtrace() */
 546 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 547                            unsigned long pc, unsigned long *ra)
 548 {
 549         unsigned long stack_page = (unsigned long)task_stack_page(task);
 550         return unwind_stack_by_address(stack_page, sp, pc, ra);
 551 }
 552 #endif
 553
 554 /*
 555  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 556  */
 557 unsigned long get_wchan(struct task_struct *task)
 558 {
 559         unsigned long pc = 0;
 560 #ifdef CONFIG_KALLSYMS
 561         unsigned long sp;
 562         unsigned long ra = 0;
 563 #endif
 564
 565         if (!task || task == current || task->state == TASK_RUNNING)
 566                 goto out;
 567         if (!task_stack_page(task))
 568                 goto out;
 569
 570         pc = thread_saved_pc(task);
 571
 572 #ifdef CONFIG_KALLSYMS
 573         sp = task->thread.reg29 + schedule_mfi.frame_size;
 574
 575         while (in_sched_functions(pc))
 576                 pc = unwind_stack(task, &sp, pc, &ra);
 577 #endif
 578
 579 out:
 580         return pc;
 581 }
 582
 583 /*
 584  * Don't forget that the stack pointer must be aligned on a 8 bytes
 585  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 586  */
 587 unsigned long arch_align_stack(unsigned long sp)
 588 {
 589         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 590                 sp -= get_random_int() & ~PAGE_MASK;
 591
 592         return sp & ALMASK;
 593 }