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         status |= KU_USER;
  64         regs->cp0_status = status;
  65         clear_used_math();
  66         clear_fpu_owner();
  67         init_dsp();
  68         regs->cp0_epc = pc;
  69         regs->regs[29] = sp;
  70 }
  71
  72 void exit_thread(void)
  73 {
  74 }
  75
  76 void flush_thread(void)
  77 {
  78 }
  79
  80 int copy_thread(unsigned long clone_flags, unsigned long usp,
  81         unsigned long arg, struct task_struct *p)
  82 {
  83         struct thread_info *ti = task_thread_info(p);
  84         struct pt_regs *childregs, *regs = current_pt_regs();
  85         unsigned long childksp;
  86         p->set_child_tid = p->clear_child_tid = NULL;
  87
  88         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
  89
  90         preempt_disable();
  91
  92         if (is_fpu_owner())
  93                 save_fp(p);
  94
  95         if (cpu_has_dsp)
  96                 save_dsp(p);
  97
  98         preempt_enable();
  99
 100         /* set up new TSS. */
 101         childregs = (struct pt_regs *) childksp - 1;
 102         /*  Put the stack after the struct pt_regs.  */
 103         childksp = (unsigned long) childregs;
 104         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 105         if (unlikely(p->flags & PF_KTHREAD)) {
 106                 unsigned long status = p->thread.cp0_status;
 107                 memset(childregs, 0, sizeof(struct pt_regs));
 108                 ti->addr_limit = KERNEL_DS;
 109                 p->thread.reg16 = usp; /* fn */
 110                 p->thread.reg17 = arg;
 111                 p->thread.reg29 = childksp;
 112                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 113 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 114                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 115                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 116 #else
 117                 status |= ST0_EXL;
 118 #endif
 119                 childregs->cp0_status = status;
 120                 return 0;
 121         }
 122         *childregs = *regs;
 123         childregs->regs[7] = 0; /* Clear error flag */
 124         childregs->regs[2] = 0; /* Child gets zero as return value */
 125         if (usp)
 126                 childregs->regs[29] = usp;
 127         ti->addr_limit = USER_DS;
 128
 129         p->thread.reg29 = (unsigned long) childregs;
 130         p->thread.reg31 = (unsigned long) ret_from_fork;
 131
 132         /*
 133          * New tasks lose permission to use the fpu. This accelerates context
 134          * switching for most programs since they don't use the fpu.
 135          */
 136         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 137
 138 #ifdef CONFIG_MIPS_MT_SMTC
 139         /*
 140          * SMTC restores TCStatus after Status, and the CU bits
 141          * are aliased there.
 142          */
 143         childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
 144 #endif
 145         clear_tsk_thread_flag(p, TIF_USEDFPU);
 146
 147 #ifdef CONFIG_MIPS_MT_FPAFF
 148         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 149 #endif /* CONFIG_MIPS_MT_FPAFF */
 150
 151         if (clone_flags & CLONE_SETTLS)
 152                 ti->tp_value = regs->regs[7];
 153
 154         return 0;
 155 }
 156
 157 /* Fill in the fpu structure for a core dump.. */
 158 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 159 {
 160         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
 161
 162         return 1;
 163 }
 164
 165 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
 166 {
 167         int i;
 168
 169         for (i = 0; i < EF_R0; i++)
 170                 gp[i] = 0;
 171         gp[EF_R0] = 0;
 172         for (i = 1; i <= 31; i++)
 173                 gp[EF_R0 + i] = regs->regs[i];
 174         gp[EF_R26] = 0;
 175         gp[EF_R27] = 0;
 176         gp[EF_LO] = regs->lo;
 177         gp[EF_HI] = regs->hi;
 178         gp[EF_CP0_EPC] = regs->cp0_epc;
 179         gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 180         gp[EF_CP0_STATUS] = regs->cp0_status;
 181         gp[EF_CP0_CAUSE] = regs->cp0_cause;
 182 #ifdef EF_UNUSED0
 183         gp[EF_UNUSED0] = 0;
 184 #endif
 185 }
 186
 187 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 188 {
 189         elf_dump_regs(*regs, task_pt_regs(tsk));
 190         return 1;
 191 }
 192
 193 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
 194 {
 195         memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
 196
 197         return 1;
 198 }
 199
 200 #ifdef CONFIG_CC_STACKPROTECTOR
 201 #include <linux/stackprotector.h>
 202 unsigned long __stack_chk_guard __read_mostly;
 203 EXPORT_SYMBOL(__stack_chk_guard);
 204 #endif
 205
 206 struct mips_frame_info {
 207         void            *func;
 208         unsigned long   func_size;
 209         int             frame_size;
 210         int             pc_offset;
 211 };
 212
 213 #define J_TARGET(pc,target)     \
 214                 (((unsigned long)(pc) & 0xf0000000) | ((target) << 2))
 215
 216 static inline int is_ra_save_ins(union mips_instruction *ip)
 217 {
 218 #ifdef CONFIG_CPU_MICROMIPS
 219         union mips_instruction mmi;
 220
 221         /*
 222          * swsp ra,offset
 223          * swm16 reglist,offset(sp)
 224          * swm32 reglist,offset(sp)
 225          * sw32 ra,offset(sp)
 226          * jradiussp - NOT SUPPORTED
 227          *
 228          * microMIPS is way more fun...
 229          */
 230         if (mm_insn_16bit(ip->halfword[0])) {
 231                 mmi.word = (ip->halfword[0] << 16);
 232                 return ((mmi.mm16_r5_format.opcode == mm_swsp16_op &&
 233                          mmi.mm16_r5_format.rt == 31) ||
 234                         (mmi.mm16_m_format.opcode == mm_pool16c_op &&
 235                          mmi.mm16_m_format.func == mm_swm16_op));
 236         }
 237         else {
 238                 mmi.halfword[0] = ip->halfword[1];
 239                 mmi.halfword[1] = ip->halfword[0];
 240                 return ((mmi.mm_m_format.opcode == mm_pool32b_op &&
 241                          mmi.mm_m_format.rd > 9 &&
 242                          mmi.mm_m_format.base == 29 &&
 243                          mmi.mm_m_format.func == mm_swm32_func) ||
 244                         (mmi.i_format.opcode == mm_sw32_op &&
 245                          mmi.i_format.rs == 29 &&
 246                          mmi.i_format.rt == 31));
 247         }
 248 #else
 249         /* sw / sd $ra, offset($sp) */
 250         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 251                 ip->i_format.rs == 29 &&
 252                 ip->i_format.rt == 31;
 253 #endif
 254 }
 255
 256 static inline int is_jump_ins(union mips_instruction *ip)
 257 {
 258 #ifdef CONFIG_CPU_MICROMIPS
 259         /*
 260          * jr16,jrc,jalr16,jalr16
 261          * jal
 262          * jalr/jr,jalr.hb/jr.hb,jalrs,jalrs.hb
 263          * jraddiusp - NOT SUPPORTED
 264          *
 265          * microMIPS is kind of more fun...
 266          */
 267         union mips_instruction mmi;
 268
 269         mmi.word = (ip->halfword[0] << 16);
 270
 271         if ((mmi.mm16_r5_format.opcode == mm_pool16c_op &&
 272             (mmi.mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op) ||
 273             ip->j_format.opcode == mm_jal32_op)
 274                 return 1;
 275         if (ip->r_format.opcode != mm_pool32a_op ||
 276                         ip->r_format.func != mm_pool32axf_op)
 277                 return 0;
 278         return (((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op);
 279 #else
 280         if (ip->j_format.opcode == j_op)
 281                 return 1;
 282         if (ip->j_format.opcode == jal_op)
 283                 return 1;
 284         if (ip->r_format.opcode != spec_op)
 285                 return 0;
 286         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 287 #endif
 288 }
 289
 290 static inline int is_sp_move_ins(union mips_instruction *ip)
 291 {
 292 #ifdef CONFIG_CPU_MICROMIPS
 293         /*
 294          * addiusp -imm
 295          * addius5 sp,-imm
 296          * addiu32 sp,sp,-imm
 297          * jradiussp - NOT SUPPORTED
 298          *
 299          * microMIPS is not more fun...
 300          */
 301         if (mm_insn_16bit(ip->halfword[0])) {
 302                 union mips_instruction mmi;
 303
 304                 mmi.word = (ip->halfword[0] << 16);
 305                 return ((mmi.mm16_r3_format.opcode == mm_pool16d_op &&
 306                          mmi.mm16_r3_format.simmediate && mm_addiusp_func) ||
 307                         (mmi.mm16_r5_format.opcode == mm_pool16d_op &&
 308                          mmi.mm16_r5_format.rt == 29));
 309         }
 310         return (ip->mm_i_format.opcode == mm_addiu32_op &&
 311                  ip->mm_i_format.rt == 29 && ip->mm_i_format.rs == 29);
 312 #else
 313         /* addiu/daddiu sp,sp,-imm */
 314         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 315                 return 0;
 316         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 317                 return 1;
 318 #endif
 319         return 0;
 320 }
 321
 322 static int get_frame_info(struct mips_frame_info *info)
 323 {
 324 #ifdef CONFIG_CPU_MICROMIPS
 325         union mips_instruction *ip = (void *) (((char *) info->func) - 1);
 326 #else
 327         union mips_instruction *ip = info->func;
 328 #endif
 329         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 330         unsigned i;
 331
 332         info->pc_offset = -1;
 333         info->frame_size = 0;
 334
 335         if (!ip)
 336                 goto err;
 337
 338         if (max_insns == 0)
 339                 max_insns = 128U;       /* unknown function size */
 340         max_insns = min(128U, max_insns);
 341
 342         for (i = 0; i < max_insns; i++, ip++) {
 343
 344                 if (is_jump_ins(ip))
 345                         break;
 346                 if (!info->frame_size) {
 347                         if (is_sp_move_ins(ip))
 348                         {
 349 #ifdef CONFIG_CPU_MICROMIPS
 350                                 if (mm_insn_16bit(ip->halfword[0]))
 351                                 {
 352                                         unsigned short tmp;
 353
 354                                         if (ip->halfword[0] & mm_addiusp_func)
 355                                         {
 356                                                 tmp = (((ip->halfword[0] >> 1) & 0x1ff) << 2);
 357                                                 info->frame_size = -(signed short)(tmp | ((tmp & 0x100) ? 0xfe00 : 0));
 358                                         } else {
 359                                                 tmp = (ip->halfword[0] >> 1);
 360                                                 info->frame_size = -(signed short)(tmp & 0xf);
 361                                         }
 362                                         ip = (void *) &ip->halfword[1];
 363                                         ip--;
 364                                 } else
 365 #endif
 366                                 info->frame_size = - ip->i_format.simmediate;
 367                         }
 368                         continue;
 369                 }
 370                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
 371                         info->pc_offset =
 372                                 ip->i_format.simmediate / sizeof(long);
 373                         break;
 374                 }
 375         }
 376         if (info->frame_size && info->pc_offset >= 0) /* nested */
 377                 return 0;
 378         if (info->pc_offset < 0) /* leaf */
 379                 return 1;
 380         /* prologue seems boggus... */
 381 err:
 382         return -1;
 383 }
 384
 385 static struct mips_frame_info schedule_mfi __read_mostly;
 386
 387 #ifdef CONFIG_KALLSYMS
 388 static unsigned long get___schedule_addr(void)
 389 {
 390         return kallsyms_lookup_name("__schedule");
 391 }
 392 #else
 393 static unsigned long get___schedule_addr(void)
 394 {
 395         union mips_instruction *ip = (void *)schedule;
 396         int max_insns = 8;
 397         int i;
 398
 399         for (i = 0; i < max_insns; i++, ip++) {
 400                 if (ip->j_format.opcode == j_op)
 401                         return J_TARGET(ip, ip->j_format.target);
 402         }
 403         return 0;
 404 }
 405 #endif
 406
 407 static int __init frame_info_init(void)
 408 {
 409         unsigned long size = 0;
 410 #ifdef CONFIG_KALLSYMS
 411         unsigned long ofs;
 412 #endif
 413         unsigned long addr;
 414
 415         addr = get___schedule_addr();
 416         if (!addr)
 417                 addr = (unsigned long)schedule;
 418
 419 #ifdef CONFIG_KALLSYMS
 420         kallsyms_lookup_size_offset(addr, &size, &ofs);
 421 #endif
 422         schedule_mfi.func = (void *)addr;
 423         schedule_mfi.func_size = size;
 424
 425         get_frame_info(&schedule_mfi);
 426
 427         /*
 428          * Without schedule() frame info, result given by
 429          * thread_saved_pc() and get_wchan() are not reliable.
 430          */
 431         if (schedule_mfi.pc_offset < 0)
 432                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 433
 434         return 0;
 435 }
 436
 437 arch_initcall(frame_info_init);
 438
 439 /*
 440  * Return saved PC of a blocked thread.
 441  */
 442 unsigned long thread_saved_pc(struct task_struct *tsk)
 443 {
 444         struct thread_struct *t = &tsk->thread;
 445
 446         /* New born processes are a special case */
 447         if (t->reg31 == (unsigned long) ret_from_fork)
 448                 return t->reg31;
 449         if (schedule_mfi.pc_offset < 0)
 450                 return 0;
 451         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 452 }
 453
 454
 455 #ifdef CONFIG_KALLSYMS
 456 /* generic stack unwinding function */
 457 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 458                                               unsigned long *sp,
 459                                               unsigned long pc,
 460                                               unsigned long *ra)
 461 {
 462         struct mips_frame_info info;
 463         unsigned long size, ofs;
 464         int leaf;
 465         extern void ret_from_irq(void);
 466         extern void ret_from_exception(void);
 467
 468         if (!stack_page)
 469                 return 0;
 470
 471         /*
 472          * If we reached the bottom of interrupt context,
 473          * return saved pc in pt_regs.
 474          */
 475         if (pc == (unsigned long)ret_from_irq ||
 476             pc == (unsigned long)ret_from_exception) {
 477                 struct pt_regs *regs;
 478                 if (*sp >= stack_page &&
 479                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
 480                         regs = (struct pt_regs *)*sp;
 481                         pc = regs->cp0_epc;
 482                         if (__kernel_text_address(pc)) {
 483                                 *sp = regs->regs[29];
 484                                 *ra = regs->regs[31];
 485                                 return pc;
 486                         }
 487                 }
 488                 return 0;
 489         }
 490         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 491                 return 0;
 492         /*
 493          * Return ra if an exception occurred at the first instruction
 494          */
 495         if (unlikely(ofs == 0)) {
 496                 pc = *ra;
 497                 *ra = 0;
 498                 return pc;
 499         }
 500
 501         info.func = (void *)(pc - ofs);
 502         info.func_size = ofs;   /* analyze from start to ofs */
 503         leaf = get_frame_info(&info);
 504         if (leaf < 0)
 505                 return 0;
 506
 507         if (*sp < stack_page ||
 508             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
 509                 return 0;
 510
 511         if (leaf)
 512                 /*
 513                  * For some extreme cases, get_frame_info() can
 514                  * consider wrongly a nested function as a leaf
 515                  * one. In that cases avoid to return always the
 516                  * same value.
 517                  */
 518                 pc = pc != *ra ? *ra : 0;
 519         else
 520                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 521
 522         *sp += info.frame_size;
 523         *ra = 0;
 524         return __kernel_text_address(pc) ? pc : 0;
 525 }
 526 EXPORT_SYMBOL(unwind_stack_by_address);
 527
 528 /* used by show_backtrace() */
 529 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 530                            unsigned long pc, unsigned long *ra)
 531 {
 532         unsigned long stack_page = (unsigned long)task_stack_page(task);
 533         return unwind_stack_by_address(stack_page, sp, pc, ra);
 534 }
 535 #endif
 536
 537 /*
 538  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 539  */
 540 unsigned long get_wchan(struct task_struct *task)
 541 {
 542         unsigned long pc = 0;
 543 #ifdef CONFIG_KALLSYMS
 544         unsigned long sp;
 545         unsigned long ra = 0;
 546 #endif
 547
 548         if (!task || task == current || task->state == TASK_RUNNING)
 549                 goto out;
 550         if (!task_stack_page(task))
 551                 goto out;
 552
 553         pc = thread_saved_pc(task);
 554
 555 #ifdef CONFIG_KALLSYMS
 556         sp = task->thread.reg29 + schedule_mfi.frame_size;
 557
 558         while (in_sched_functions(pc))
 559                 pc = unwind_stack(task, &sp, pc, &ra);
 560 #endif
 561
 562 out:
 563         return pc;
 564 }
 565
 566 /*
 567  * Don't forget that the stack pointer must be aligned on a 8 bytes
 568  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 569  */
 570 unsigned long arch_align_stack(unsigned long sp)
 571 {
 572         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 573                 sp -= get_random_int() & ~PAGE_MASK;
 574
 575         return sp & ALMASK;
 576 }