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 asmlinkage void ret_from_fork(void);
  55 asmlinkage void ret_from_kernel_thread(void);
  56
  57 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  58 {
  59         unsigned long status;
  60
  61         /* New thread loses kernel privileges. */
  62         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
  63 #ifdef CONFIG_64BIT
  64         status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
  65 #endif
  66         status |= KU_USER;
  67         regs->cp0_status = status;
  68         clear_used_math();
  69         clear_fpu_owner();
  70         if (cpu_has_dsp)
  71                 __init_dsp();
  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_fpu_owner())
  97                 save_fp(p);
  98
  99         if (cpu_has_dsp)
 100                 save_dsp(p);
 101
 102         preempt_enable();
 103
 104         /* set up new TSS. */
 105         childregs = (struct pt_regs *) childksp - 1;
 106         /*  Put the stack after the struct pt_regs.  */
 107         childksp = (unsigned long) childregs;
 108         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 109         if (unlikely(p->flags & PF_KTHREAD)) {
 110                 unsigned long status = p->thread.cp0_status;
 111                 memset(childregs, 0, sizeof(struct pt_regs));
 112                 ti->addr_limit = KERNEL_DS;
 113                 p->thread.reg16 = usp; /* fn */
 114                 p->thread.reg17 = arg;
 115                 p->thread.reg29 = childksp;
 116                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 117 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 118                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 119                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 120 #else
 121                 status |= ST0_EXL;
 122 #endif
 123                 childregs->cp0_status = status;
 124                 return 0;
 125         }
 126         *childregs = *regs;
 127         childregs->regs[7] = 0; /* Clear error flag */
 128         childregs->regs[2] = 0; /* Child gets zero as return value */
 129         if (usp)
 130                 childregs->regs[29] = usp;
 131         ti->addr_limit = USER_DS;
 132
 133         p->thread.reg29 = (unsigned long) childregs;
 134         p->thread.reg31 = (unsigned long) ret_from_fork;
 135
 136         /*
 137          * New tasks lose permission to use the fpu. This accelerates context
 138          * switching for most programs since they don't use the fpu.
 139          */
 140         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 141
 142 #ifdef CONFIG_MIPS_MT_SMTC
 143         /*
 144          * SMTC restores TCStatus after Status, and the CU bits
 145          * are aliased there.
 146          */
 147         childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
 148 #endif
 149         clear_tsk_thread_flag(p, TIF_USEDFPU);
 150
 151 #ifdef CONFIG_MIPS_MT_FPAFF
 152         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 153 #endif /* CONFIG_MIPS_MT_FPAFF */
 154
 155         if (clone_flags & CLONE_SETTLS)
 156                 ti->tp_value = regs->regs[7];
 157
 158         return 0;
 159 }
 160
 161 /* Fill in the fpu structure for a core dump.. */
 162 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 163 {
 164         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
 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         memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
 200
 201         return 1;
 202 }
 203
 204 /*
 205  *
 206  */
 207 struct mips_frame_info {
 208         void            *func;
 209         unsigned long   func_size;
 210         int             frame_size;
 211         int             pc_offset;
 212 };
 213
 214 #define J_TARGET(pc,target)     \
 215                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 216
 217 static inline int is_ra_save_ins(union mips_instruction *ip)
 218 {
 219 #ifdef CONFIG_CPU_MICROMIPS
 220         union mips_instruction mmi;
 221
 222         /*
 223          * swsp ra,offset
 224          * swm16 reglist,offset(sp)
 225          * swm32 reglist,offset(sp)
 226          * sw32 ra,offset(sp)
 227          * jradiussp - NOT SUPPORTED
 228          *
 229          * microMIPS is way more fun...
 230          */
 231         if (mm_insn_16bit(ip->halfword[0])) {
 232                 mmi.word = (ip->halfword[0] << 16);
 233                 return ((mmi.mm16_r5_format.opcode == mm_swsp16_op &&
 234                          mmi.mm16_r5_format.rt == 31) ||
 235                         (mmi.mm16_m_format.opcode == mm_pool16c_op &&
 236                          mmi.mm16_m_format.func == mm_swm16_op));
 237         }
 238         else {
 239                 mmi.halfword[0] = ip->halfword[1];
 240                 mmi.halfword[1] = ip->halfword[0];
 241                 return ((mmi.mm_m_format.opcode == mm_pool32b_op &&
 242                          mmi.mm_m_format.rd > 9 &&
 243                          mmi.mm_m_format.base == 29 &&
 244                          mmi.mm_m_format.func == mm_swm32_func) ||
 245                         (mmi.i_format.opcode == mm_sw32_op &&
 246                          mmi.i_format.rs == 29 &&
 247                          mmi.i_format.rt == 31));
 248         }
 249 #else
 250         /* sw / sd $ra, offset($sp) */
 251         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 252                 ip->i_format.rs == 29 &&
 253                 ip->i_format.rt == 31;
 254 #endif
 255 }
 256
 257 static inline int is_jump_ins(union mips_instruction *ip)
 258 {
 259 #ifdef CONFIG_CPU_MICROMIPS
 260         /*
 261          * jr16,jrc,jalr16,jalr16
 262          * jal
 263          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 264          * jraddiusp - NOT SUPPORTED
 265          *
 266          * microMIPS is kind of more fun...
 267          */
 268         union mips_instruction mmi;
 269
 270         mmi.word = (ip->halfword[0] << 16);
 271
 272         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
 273             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
 274             ip->j_format.opcode == mm_jal32_op)
 275                 return 1;
 276         if (ip->r_format.opcode != mm_pool32a_op ||
 277                         ip->r_format.func != mm_pool32axf_op)
 278                 return 0;
 279         return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
 280 #else
 281         if (ip->j_format.opcode == j_op)
 282                 return 1;
 283         if (ip->j_format.opcode == jal_op)
 284                 return 1;
 285         if (ip->r_format.opcode != spec_op)
 286                 return 0;
 287         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 288 #endif
 289 }
 290
 291 static inline int is_sp_move_ins(union mips_instruction *ip)
 292 {
 293 #ifdef CONFIG_CPU_MICROMIPS
 294         /*
 295          * addiusp -imm
 296          * addius5 sp,-imm
 297          * addiu32 sp,sp,-imm
 298          * jradiussp - NOT SUPPORTED
 299          *
 300          * microMIPS is not more fun...
 301          */
 302         if (mm_insn_16bit(ip->halfword[0])) {
 303                 union mips_instruction mmi;
 304
 305                 mmi.word = (ip->halfword[0] << 16);
 306                 return ((mmi.mm16_r3_format.opcode == mm_pool16d_op &&
 307                          mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
 308                         (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
 309                          mmi.mm16_r5_format.rt == 29));
 310         }
 311         return (ip->mm_i_format.opcode == mm_addiu32_op &&
 312                  ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29);
 313 #else
 314         /* addiu/daddiu sp,sp,-imm */
 315         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 316                 return 0;
 317         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 318                 return 1;
 319 #endif
 320         return 0;
 321 }
 322
 323 static int get_frame_info(struct mips_frame_info *info)
 324 {
 325 #ifdef CONFIG_CPU_MICROMIPS
 326         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
 327 #else
 328         union mips_instruction *ip = info->func;
 329 #endif
 330         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 331         unsigned i;
 332
 333         info->pc_offset = -1;
 334         info->frame_size = 0;
 335
 336         if (!ip)
 337                 goto err;
 338
 339         if (max_insns == 0)
 340                 max_insns = 128U;       /* unknown function size */
 341         max_insns = min(128U, max_insns);
 342
 343         for (i = 0; i < max_insns; i++, ip++) {
 344
 345                 if (is_jump_ins(ip))
 346                         break;
 347                 if (!info->frame_size) {
 348                         if (is_sp_move_ins(ip))
 349                         {
 350 #ifdef CONFIG_CPU_MICROMIPS
 351                                 if (mm_insn_16bit(ip->halfword[0]))
 352                                 {
 353                                         unsigned short tmp;
 354
 355                                         if (ip->halfword[0] & mm_addiusp_func)
 356                                         {
 357                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 358                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 359                                         } else {
 360                                                 tmp = (ip->halfword[0] >> 1);
 361                                                 info->frame_size = -(signed short)(tmp & 0xf);
 362                                         }
 363                                         ip = (void *) &ip->halfword[1];
 364                                         ip--;
 365                                 } else
 366 #endif
 367                                 info->frame_size = - ip->i_format.simmediate;
 368                         }
 369                         continue;
 370                 }
 371                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
 372                         info->pc_offset =
 373                                 ip->i_format.simmediate / sizeof(long);
 374                         break;
 375                 }
 376         }
 377         if (info->frame_size && info->pc_offset >= 0) /* nested */
 378                 return 0;
 379         if (info->pc_offset < 0) /* leaf */
 380                 return 1;
 381         /* prologue seems boggus... */
 382 err:
 383         return -1;
 384 }
 385
 386 static struct mips_frame_info schedule_mfi __read_mostly;
 387
 388 #ifdef CONFIG_KALLSYMS
 389 static unsigned long get___schedule_addr(void)
 390 {
 391         return kallsyms_lookup_name("__schedule");
 392 }
 393 #else
 394 static unsigned long get___schedule_addr(void)
 395 {
 396         union mips_instruction *ip = (void *)schedule;
 397         int max_insns = 8;
 398         int i;
 399
 400         for (i = 0; i < max_insns; i++, ip++) {
 401                 if (ip->j_format.opcode == j_op)
 402                         return J_TARGET(ip, ip->j_format.target);
 403         }
 404         return 0;
 405 }
 406 #endif
 407
 408 static int __init frame_info_init(void)
 409 {
 410         unsigned long size = 0;
 411 #ifdef CONFIG_KALLSYMS
 412         unsigned long ofs;
 413 #endif
 414         unsigned long addr;
 415
 416         addr = get___schedule_addr();
 417         if (!addr)
 418                 addr = (unsigned long)schedule;
 419
 420 #ifdef CONFIG_KALLSYMS
 421         kallsyms_lookup_size_offset(addr, &size, &ofs);
 422 #endif
 423         schedule_mfi.func = (void *)addr;
 424         schedule_mfi.func_size = size;
 425
 426         get_frame_info(&schedule_mfi);
 427
 428         /*
 429          * Without schedule() frame info, result given by
 430          * thread_saved_pc() and get_wchan() are not reliable.
 431          */
 432         if (schedule_mfi.pc_offset < 0)
 433                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 434
 435         return 0;
 436 }
 437
 438 arch_initcall(frame_info_init);
 439
 440 /*
 441  * Return saved PC of a blocked thread.
 442  */
 443 unsigned long thread_saved_pc(struct task_struct *tsk)
 444 {
 445         struct thread_struct *t = &tsk->thread;
 446
 447         /* New born processes are a special case */
 448         if (t->reg31 == (unsigned long) ret_from_fork)
 449                 return t->reg31;
 450         if (schedule_mfi.pc_offset < 0)
 451                 return 0;
 452         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 453 }
 454
 455
 456 #ifdef CONFIG_KALLSYMS
 457 /* generic stack unwinding function */
 458 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 459                                               unsigned long *sp,
 460                                               unsigned long pc,
 461                                               unsigned long *ra)
 462 {
 463         struct mips_frame_info info;
 464         unsigned long size, ofs;
 465         int leaf;
 466         extern void ret_from_irq(void);
 467         extern void ret_from_exception(void);
 468
 469         if (!stack_page)
 470                 return 0;
 471
 472         /*
 473          * If we reached the bottom of interrupt context,
 474          * return saved pc in pt_regs.
 475          */
 476         if (pc == (unsigned long)ret_from_irq ||
 477             pc == (unsigned long)ret_from_exception) {
 478                 struct pt_regs *regs;
 479                 if (*sp >= stack_page &&
 480                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
 481                         regs = (struct pt_regs *)*sp;
 482                         pc = regs->cp0_epc;
 483                         if (__kernel_text_address(pc)) {
 484                                 *sp = regs->regs[29];
 485                                 *ra = regs->regs[31];
 486                                 return pc;
 487                         }
 488                 }
 489                 return 0;
 490         }
 491         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 492                 return 0;
 493         /*
 494          * Return ra if an exception occurred at the first instruction
 495          */
 496         if (unlikely(ofs == 0)) {
 497                 pc = *ra;
 498                 *ra = 0;
 499                 return pc;
 500         }
 501
 502         info.func = (void *)(pc - ofs);
 503         info.func_size = ofs;   /* analyze from start to ofs */
 504         leaf = get_frame_info(&info);
 505         if (leaf < 0)
 506                 return 0;
 507
 508         if (*sp < stack_page ||
 509             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
 510                 return 0;
 511
 512         if (leaf)
 513                 /*
 514                  * For some extreme cases, get_frame_info() can
 515                  * consider wrongly a nested function as a leaf
 516                  * one. In that cases avoid to return always the
 517                  * same value.
 518                  */
 519                 pc = pc != *ra ? *ra : 0;
 520         else
 521                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 522
 523         *sp += info.frame_size;
 524         *ra = 0;
 525         return __kernel_text_address(pc) ? pc : 0;
 526 }
 527 EXPORT_SYMBOL(unwind_stack_by_address);
 528
 529 /* used by show_backtrace() */
 530 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 531                            unsigned long pc, unsigned long *ra)
 532 {
 533         unsigned long stack_page = (unsigned long)task_stack_page(task);
 534         return unwind_stack_by_address(stack_page, sp, pc, ra);
 535 }
 536 #endif
 537
 538 /*
 539  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 540  */
 541 unsigned long get_wchan(struct task_struct *task)
 542 {
 543         unsigned long pc = 0;
 544 #ifdef CONFIG_KALLSYMS
 545         unsigned long sp;
 546         unsigned long ra = 0;
 547 #endif
 548
 549         if (!task || task == current || task->state == TASK_RUNNING)
 550                 goto out;
 551         if (!task_stack_page(task))
 552                 goto out;
 553
 554         pc = thread_saved_pc(task);
 555
 556 #ifdef CONFIG_KALLSYMS
 557         sp = task->thread.reg29 + schedule_mfi.frame_size;
 558
 559         while (in_sched_functions(pc))
 560                 pc = unwind_stack(task, &sp, pc, &ra);
 561 #endif
 562
 563 out:
 564         return pc;
 565 }
 566
 567 /*
 568  * Don't forget that the stack pointer must be aligned on a 8 bytes
 569  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 570  */
 571 unsigned long arch_align_stack(unsigned long sp)
 572 {
 573         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 574                 sp -= get_random_int() & ~PAGE_MASK;
 575
 576         return sp & ALMASK;
 577 }