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