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  */
  11 #include <linux/errno.h>
  12 #include <linux/sched.h>
  13 #include <linux/tick.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/stddef.h>
  17 #include <linux/unistd.h>
  18 #include <linux/export.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/mman.h>
  21 #include <linux/personality.h>
  22 #include <linux/sys.h>
  23 #include <linux/user.h>
  24 #include <linux/init.h>
  25 #include <linux/completion.h>
  26 #include <linux/kallsyms.h>
  27 #include <linux/random.h>
  28
  29 #include <asm/asm.h>
  30 #include <asm/bootinfo.h>
  31 #include <asm/cpu.h>
  32 #include <asm/dsp.h>
  33 #include <asm/fpu.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/mipsregs.h>
  36 #include <asm/processor.h>
  37 #include <asm/uaccess.h>
  38 #include <asm/io.h>
  39 #include <asm/elf.h>
  40 #include <asm/isadep.h>
  41 #include <asm/inst.h>
  42 #include <asm/stacktrace.h>
  43
  44 #ifdef CONFIG_HOTPLUG_CPU
  45 void arch_cpu_idle_dead(void)
  46 {
  47         /* What the heck is this check doing ? */
  48         if (!cpu_isset(smp_processor_id(), cpu_callin_map))
  49                 play_dead();
  50 }
  51 #endif
  52
  53 void arch_cpu_idle(void)
  54 {
  55 #ifdef CONFIG_MIPS_MT_SMTC
  56         extern void smtc_idle_loop_hook(void);
  57
  58         smtc_idle_loop_hook();
  59 #endif
  60         if (cpu_wait)
  61                 (*cpu_wait)();
  62         else
  63                 local_irq_enable();
  64 }
  65
  66 asmlinkage void ret_from_fork(void);
  67 asmlinkage void ret_from_kernel_thread(void);
  68
  69 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  70 {
  71         unsigned long status;
  72
  73         /* New thread loses kernel privileges. */
  74         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|ST0_FR|KU_MASK);
  75 #ifdef CONFIG_64BIT
  76         status |= test_thread_flag(TIF_32BIT_REGS) ? 0 : ST0_FR;
  77 #endif
  78         status |= KU_USER;
  79         regs->cp0_status = status;
  80         clear_used_math();
  81         clear_fpu_owner();
  82         if (cpu_has_dsp)
  83                 __init_dsp();
  84         regs->cp0_epc = pc;
  85         regs->regs[29] = sp;
  86 }
  87
  88 void exit_thread(void)
  89 {
  90 }
  91
  92 void flush_thread(void)
  93 {
  94 }
  95
  96 int copy_thread(unsigned long clone_flags, unsigned long usp,
  97         unsigned long arg, struct task_struct *p)
  98 {
  99         struct thread_info *ti = task_thread_info(p);
 100         struct pt_regs *childregs, *regs = current_pt_regs();
 101         unsigned long childksp;
 102         p->set_child_tid = p->clear_child_tid = NULL;
 103
 104         childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
 105
 106         preempt_disable();
 107
 108         if (is_fpu_owner())
 109                 save_fp(p);
 110
 111         if (cpu_has_dsp)
 112                 save_dsp(p);
 113
 114         preempt_enable();
 115
 116         /* set up new TSS. */
 117         childregs = (struct pt_regs *) childksp - 1;
 118         /*  Put the stack after the struct pt_regs.  */
 119         childksp = (unsigned long) childregs;
 120         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 121         if (unlikely(p->flags & PF_KTHREAD)) {
 122                 unsigned long status = p->thread.cp0_status;
 123                 memset(childregs, 0, sizeof(struct pt_regs));
 124                 ti->addr_limit = KERNEL_DS;
 125                 p->thread.reg16 = usp; /* fn */
 126                 p->thread.reg17 = arg;
 127                 p->thread.reg29 = childksp;
 128                 p->thread.reg31 = (unsigned long) ret_from_kernel_thread;
 129 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 130                 status = (status & ~(ST0_KUP | ST0_IEP | ST0_IEC)) |
 131                          ((status & (ST0_KUC | ST0_IEC)) << 2);
 132 #else
 133                 status |= ST0_EXL;
 134 #endif
 135                 childregs->cp0_status = status;
 136                 return 0;
 137         }
 138         *childregs = *regs;
 139         childregs->regs[7] = 0; /* Clear error flag */
 140         childregs->regs[2] = 0; /* Child gets zero as return value */
 141         if (usp)
 142                 childregs->regs[29] = usp;
 143         ti->addr_limit = USER_DS;
 144
 145         p->thread.reg29 = (unsigned long) childregs;
 146         p->thread.reg31 = (unsigned long) ret_from_fork;
 147
 148         /*
 149          * New tasks lose permission to use the fpu. This accelerates context
 150          * switching for most programs since they don't use the fpu.
 151          */
 152         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 153
 154 #ifdef CONFIG_MIPS_MT_SMTC
 155         /*
 156          * SMTC restores TCStatus after Status, and the CU bits
 157          * are aliased there.
 158          */
 159         childregs->cp0_tcstatus &= ~(ST0_CU2|ST0_CU1);
 160 #endif
 161         clear_tsk_thread_flag(p, TIF_USEDFPU);
 162
 163 #ifdef CONFIG_MIPS_MT_FPAFF
 164         clear_tsk_thread_flag(p, TIF_FPUBOUND);
 165 #endif /* CONFIG_MIPS_MT_FPAFF */
 166
 167         if (clone_flags & CLONE_SETTLS)
 168                 ti->tp_value = regs->regs[7];
 169
 170         return 0;
 171 }
 172
 173 /* Fill in the fpu structure for a core dump.. */
 174 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 175 {
 176         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
 177
 178         return 1;
 179 }
 180
 181 void elf_dump_regs(elf_greg_t *gp, struct pt_regs *regs)
 182 {
 183         int i;
 184
 185         for (i = 0; i < EF_R0; i++)
 186                 gp[i] = 0;
 187         gp[EF_R0] = 0;
 188         for (i = 1; i <= 31; i++)
 189                 gp[EF_R0 + i] = regs->regs[i];
 190         gp[EF_R26] = 0;
 191         gp[EF_R27] = 0;
 192         gp[EF_LO] = regs->lo;
 193         gp[EF_HI] = regs->hi;
 194         gp[EF_CP0_EPC] = regs->cp0_epc;
 195         gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 196         gp[EF_CP0_STATUS] = regs->cp0_status;
 197         gp[EF_CP0_CAUSE] = regs->cp0_cause;
 198 #ifdef EF_UNUSED0
 199         gp[EF_UNUSED0] = 0;
 200 #endif
 201 }
 202
 203 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
 204 {
 205         elf_dump_regs(*regs, task_pt_regs(tsk));
 206         return 1;
 207 }
 208
 209 int dump_task_fpu(struct task_struct *t, elf_fpregset_t *fpr)
 210 {
 211         memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
 212
 213         return 1;
 214 }
 215
 216 /*
 217  *
 218  */
 219 struct mips_frame_info {
 220         void            *func;
 221         unsigned long   func_size;
 222         int             frame_size;
 223         int             pc_offset;
 224 };
 225
 226 static inline int is_ra_save_ins(union mips_instruction *ip)
 227 {
 228         /* sw / sd $ra, offset($sp) */
 229         return (ip->i_format.opcode == sw_op || ip->i_format.opcode == sd_op) &&
 230                 ip->i_format.rs == 29 &&
 231                 ip->i_format.rt == 31;
 232 }
 233
 234 static inline int is_jal_jalr_jr_ins(union mips_instruction *ip)
 235 {
 236         if (ip->j_format.opcode == jal_op)
 237                 return 1;
 238         if (ip->r_format.opcode != spec_op)
 239                 return 0;
 240         return ip->r_format.func == jalr_op || ip->r_format.func == jr_op;
 241 }
 242
 243 static inline int is_sp_move_ins(union mips_instruction *ip)
 244 {
 245         /* addiu/daddiu sp,sp,-imm */
 246         if (ip->i_format.rs != 29 || ip->i_format.rt != 29)
 247                 return 0;
 248         if (ip->i_format.opcode == addiu_op || ip->i_format.opcode == daddiu_op)
 249                 return 1;
 250         return 0;
 251 }
 252
 253 static int get_frame_info(struct mips_frame_info *info)
 254 {
 255         union mips_instruction *ip = info->func;
 256         unsigned max_insns = info->func_size / sizeof(union mips_instruction);
 257         unsigned i;
 258
 259         info->pc_offset = -1;
 260         info->frame_size = 0;
 261
 262         if (!ip)
 263                 goto err;
 264
 265         if (max_insns == 0)
 266                 max_insns = 128U;       /* unknown function size */
 267         max_insns = min(128U, max_insns);
 268
 269         for (i = 0; i < max_insns; i++, ip++) {
 270
 271                 if (is_jal_jalr_jr_ins(ip))
 272                         break;
 273                 if (!info->frame_size) {
 274                         if (is_sp_move_ins(ip))
 275                                 info->frame_size = - ip->i_format.simmediate;
 276                         continue;
 277                 }
 278                 if (info->pc_offset == -1 && is_ra_save_ins(ip)) {
 279                         info->pc_offset =
 280                                 ip->i_format.simmediate / sizeof(long);
 281                         break;
 282                 }
 283         }
 284         if (info->frame_size && info->pc_offset >= 0) /* nested */
 285                 return 0;
 286         if (info->pc_offset < 0) /* leaf */
 287                 return 1;
 288         /* prologue seems boggus... */
 289 err:
 290         return -1;
 291 }
 292
 293 static struct mips_frame_info schedule_mfi __read_mostly;
 294
 295 static int __init frame_info_init(void)
 296 {
 297         unsigned long size = 0;
 298 #ifdef CONFIG_KALLSYMS
 299         unsigned long ofs;
 300
 301         kallsyms_lookup_size_offset((unsigned long)schedule, &size, &ofs);
 302 #endif
 303         schedule_mfi.func = schedule;
 304         schedule_mfi.func_size = size;
 305
 306         get_frame_info(&schedule_mfi);
 307
 308         /*
 309          * Without schedule() frame info, result given by
 310          * thread_saved_pc() and get_wchan() are not reliable.
 311          */
 312         if (schedule_mfi.pc_offset < 0)
 313                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 314
 315         return 0;
 316 }
 317
 318 arch_initcall(frame_info_init);
 319
 320 /*
 321  * Return saved PC of a blocked thread.
 322  */
 323 unsigned long thread_saved_pc(struct task_struct *tsk)
 324 {
 325         struct thread_struct *t = &tsk->thread;
 326
 327         /* New born processes are a special case */
 328         if (t->reg31 == (unsigned long) ret_from_fork)
 329                 return t->reg31;
 330         if (schedule_mfi.pc_offset < 0)
 331                 return 0;
 332         return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 333 }
 334
 335
 336 #ifdef CONFIG_KALLSYMS
 337 /* generic stack unwinding function */
 338 unsigned long notrace unwind_stack_by_address(unsigned long stack_page,
 339                                               unsigned long *sp,
 340                                               unsigned long pc,
 341                                               unsigned long *ra)
 342 {
 343         struct mips_frame_info info;
 344         unsigned long size, ofs;
 345         int leaf;
 346         extern void ret_from_irq(void);
 347         extern void ret_from_exception(void);
 348
 349         if (!stack_page)
 350                 return 0;
 351
 352         /*
 353          * If we reached the bottom of interrupt context,
 354          * return saved pc in pt_regs.
 355          */
 356         if (pc == (unsigned long)ret_from_irq ||
 357             pc == (unsigned long)ret_from_exception) {
 358                 struct pt_regs *regs;
 359                 if (*sp >= stack_page &&
 360                     *sp + sizeof(*regs) <= stack_page + THREAD_SIZE - 32) {
 361                         regs = (struct pt_regs *)*sp;
 362                         pc = regs->cp0_epc;
 363                         if (__kernel_text_address(pc)) {
 364                                 *sp = regs->regs[29];
 365                                 *ra = regs->regs[31];
 366                                 return pc;
 367                         }
 368                 }
 369                 return 0;
 370         }
 371         if (!kallsyms_lookup_size_offset(pc, &size, &ofs))
 372                 return 0;
 373         /*
 374          * Return ra if an exception occurred at the first instruction
 375          */
 376         if (unlikely(ofs == 0)) {
 377                 pc = *ra;
 378                 *ra = 0;
 379                 return pc;
 380         }
 381
 382         info.func = (void *)(pc - ofs);
 383         info.func_size = ofs;   /* analyze from start to ofs */
 384         leaf = get_frame_info(&info);
 385         if (leaf < 0)
 386                 return 0;
 387
 388         if (*sp < stack_page ||
 389             *sp + info.frame_size > stack_page + THREAD_SIZE - 32)
 390                 return 0;
 391
 392         if (leaf)
 393                 /*
 394                  * For some extreme cases, get_frame_info() can
 395                  * consider wrongly a nested function as a leaf
 396                  * one. In that cases avoid to return always the
 397                  * same value.
 398                  */
 399                 pc = pc != *ra ? *ra : 0;
 400         else
 401                 pc = ((unsigned long *)(*sp))[info.pc_offset];
 402
 403         *sp += info.frame_size;
 404         *ra = 0;
 405         return __kernel_text_address(pc) ? pc : 0;
 406 }
 407 EXPORT_SYMBOL(unwind_stack_by_address);
 408
 409 /* used by show_backtrace() */
 410 unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
 411                            unsigned long pc, unsigned long *ra)
 412 {
 413         unsigned long stack_page = (unsigned long)task_stack_page(task);
 414         return unwind_stack_by_address(stack_page, sp, pc, ra);
 415 }
 416 #endif
 417
 418 /*
 419  * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
 420  */
 421 unsigned long get_wchan(struct task_struct *task)
 422 {
 423         unsigned long pc = 0;
 424 #ifdef CONFIG_KALLSYMS
 425         unsigned long sp;
 426         unsigned long ra = 0;
 427 #endif
 428
 429         if (!task || task == current || task->state == TASK_RUNNING)
 430                 goto out;
 431         if (!task_stack_page(task))
 432                 goto out;
 433
 434         pc = thread_saved_pc(task);
 435
 436 #ifdef CONFIG_KALLSYMS
 437         sp = task->thread.reg29 + schedule_mfi.frame_size;
 438
 439         while (in_sched_functions(pc))
 440                 pc = unwind_stack(task, &sp, pc, &ra);
 441 #endif
 442
 443 out:
 444         return pc;
 445 }
 446
 447 /*
 448  * Don't forget that the stack pointer must be aligned on a 8 bytes
 449  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 450  */
 451 unsigned long arch_align_stack(unsigned long sp)
 452 {
 453         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 454                 sp -= get_random_int() & ~PAGE_MASK;
 455
 456         return sp & ALMASK;
 457 }