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) 1999, 2000 Silicon Graphics, Inc.
   8  * Copyright (C) 2004 Thiemo Seufer
   9  */
  10 #include <linux/config.h>
  11 #include <linux/errno.h>
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/stddef.h>
  17 #include <linux/unistd.h>
  18 #include <linux/ptrace.h>
  19 #include <linux/slab.h>
  20 #include <linux/mman.h>
  21 #include <linux/personality.h>
  22 #include <linux/sys.h>
  23 #include <linux/user.h>
  24 #include <linux/a.out.h>
  25 #include <linux/init.h>
  26 #include <linux/completion.h>
  27
  28 #include <asm/abi.h>
  29 #include <asm/bootinfo.h>
  30 #include <asm/cpu.h>
  31 #include <asm/dsp.h>
  32 #include <asm/fpu.h>
  33 #include <asm/pgtable.h>
  34 #include <asm/system.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
  43 /*
  44  * The idle thread. There's no useful work to be done, so just try to conserve
  45  * power and have a low exit latency (ie sit in a loop waiting for somebody to
  46  * say that they'd like to reschedule)
  47  */
  48 ATTRIB_NORET void cpu_idle(void)
  49 {
  50         /* endless idle loop with no priority at all */
  51         while (1) {
  52                 while (!need_resched())
  53                         if (cpu_wait)
  54                                 (*cpu_wait)();
  55                 preempt_enable_no_resched();
  56                 schedule();
  57                 preempt_disable();
  58         }
  59 }
  60
  61 extern int do_signal(sigset_t *oldset, struct pt_regs *regs);
  62 extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);
  63
  64 /*
  65  * Native o32 and N64 ABI without DSP ASE
  66  */
  67 extern int setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
  68         int signr, sigset_t *set);
  69 extern int setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
  70         int signr, sigset_t *set, siginfo_t *info);
  71
  72 struct mips_abi mips_abi = {
  73         .do_signal      = do_signal,
  74 #ifdef CONFIG_TRAD_SIGNALS
  75         .setup_frame    = setup_frame,
  76 #endif
  77         .setup_rt_frame = setup_rt_frame
  78 };
  79
  80 #ifdef CONFIG_MIPS32_O32
  81 /*
  82  * o32 compatibility on 64-bit kernels, without DSP ASE
  83  */
  84 extern int setup_frame_32(struct k_sigaction * ka, struct pt_regs *regs,
  85         int signr, sigset_t *set);
  86 extern int setup_rt_frame_32(struct k_sigaction * ka, struct pt_regs *regs,
  87         int signr, sigset_t *set, siginfo_t *info);
  88
  89 struct mips_abi mips_abi_32 = {
  90         .do_signal      = do_signal32,
  91         .setup_frame    = setup_frame_32,
  92         .setup_rt_frame = setup_rt_frame_32
  93 };
  94 #endif /* CONFIG_MIPS32_O32 */
  95
  96 #ifdef CONFIG_MIPS32_N32
  97 /*
  98  * N32 on 64-bit kernels, without DSP ASE
  99  */
 100 extern int setup_rt_frame_n32(struct k_sigaction * ka, struct pt_regs *regs,
 101         int signr, sigset_t *set, siginfo_t *info);
 102
 103 struct mips_abi mips_abi_n32 = {
 104         .do_signal      = do_signal,
 105         .setup_rt_frame = setup_rt_frame_n32
 106 };
 107 #endif /* CONFIG_MIPS32_N32 */
 108
 109 asmlinkage void ret_from_fork(void);
 110
 111 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
 112 {
 113         unsigned long status;
 114
 115         /* New thread loses kernel privileges. */
 116         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK);
 117 #ifdef CONFIG_64BIT
 118         status &= ~ST0_FR;
 119         status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
 120 #endif
 121         status |= KU_USER;
 122         regs->cp0_status = status;
 123         clear_used_math();
 124         lose_fpu();
 125         if (cpu_has_dsp)
 126                 __init_dsp();
 127         regs->cp0_epc = pc;
 128         regs->regs[29] = sp;
 129         current_thread_info()->addr_limit = USER_DS;
 130 }
 131
 132 void exit_thread(void)
 133 {
 134 }
 135
 136 void flush_thread(void)
 137 {
 138 }
 139
 140 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 141         unsigned long unused, struct task_struct *p, struct pt_regs *regs)
 142 {
 143         struct thread_info *ti = p->thread_info;
 144         struct pt_regs *childregs;
 145         long childksp;
 146         p->set_child_tid = p->clear_child_tid = NULL;
 147
 148         childksp = (unsigned long)ti + THREAD_SIZE - 32;
 149
 150         preempt_disable();
 151
 152         if (is_fpu_owner())
 153                 save_fp(p);
 154
 155         if (cpu_has_dsp)
 156                 save_dsp(p);
 157
 158         preempt_enable();
 159
 160         /* set up new TSS. */
 161         childregs = (struct pt_regs *) childksp - 1;
 162         *childregs = *regs;
 163         childregs->regs[7] = 0; /* Clear error flag */
 164
 165 #if defined(CONFIG_BINFMT_IRIX)
 166         if (current->personality != PER_LINUX) {
 167                 /* Under IRIX things are a little different. */
 168                 childregs->regs[3] = 1;
 169                 regs->regs[3] = 0;
 170         }
 171 #endif
 172         childregs->regs[2] = 0; /* Child gets zero as return value */
 173         regs->regs[2] = p->pid;
 174
 175         if (childregs->cp0_status & ST0_CU0) {
 176                 childregs->regs[28] = (unsigned long) ti;
 177                 childregs->regs[29] = childksp;
 178                 ti->addr_limit = KERNEL_DS;
 179         } else {
 180                 childregs->regs[29] = usp;
 181                 ti->addr_limit = USER_DS;
 182         }
 183         p->thread.reg29 = (unsigned long) childregs;
 184         p->thread.reg31 = (unsigned long) ret_from_fork;
 185
 186         /*
 187          * New tasks lose permission to use the fpu. This accelerates context
 188          * switching for most programs since they don't use the fpu.
 189          */
 190         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 191         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 192         clear_tsk_thread_flag(p, TIF_USEDFPU);
 193
 194         if (clone_flags & CLONE_SETTLS)
 195                 ti->tp_value = regs->regs[7];
 196
 197         return 0;
 198 }
 199
 200 /* Fill in the fpu structure for a core dump.. */
 201 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 202 {
 203         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
 204
 205         return 1;
 206 }
 207
 208 void dump_regs(elf_greg_t *gp, struct pt_regs *regs)
 209 {
 210         int i;
 211
 212         for (i = 0; i < EF_R0; i++)
 213                 gp[i] = 0;
 214         gp[EF_R0] = 0;
 215         for (i = 1; i <= 31; i++)
 216                 gp[EF_R0 + i] = regs->regs[i];
 217         gp[EF_R26] = 0;
 218         gp[EF_R27] = 0;
 219         gp[EF_LO] = regs->lo;
 220         gp[EF_HI] = regs->hi;
 221         gp[EF_CP0_EPC] = regs->cp0_epc;
 222         gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 223         gp[EF_CP0_STATUS] = regs->cp0_status;
 224         gp[EF_CP0_CAUSE] = regs->cp0_cause;
 225 #ifdef EF_UNUSED0
 226         gp[EF_UNUSED0] = 0;
 227 #endif
 228 }
 229
 230 int dump_task_regs (struct task_struct *tsk, elf_gregset_t *regs)
 231 {
 232         struct thread_info *ti = tsk->thread_info;
 233         long ksp = (unsigned long)ti + THREAD_SIZE - 32;
 234         dump_regs(&(*regs)[0], (struct pt_regs *) ksp - 1);
 235         return 1;
 236 }
 237
 238 int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr)
 239 {
 240         memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
 241
 242         return 1;
 243 }
 244
 245 /*
 246  * Create a kernel thread
 247  */
 248 ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
 249 {
 250         do_exit(fn(arg));
 251 }
 252
 253 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 254 {
 255         struct pt_regs regs;
 256
 257         memset(&regs, 0, sizeof(regs));
 258
 259         regs.regs[4] = (unsigned long) arg;
 260         regs.regs[5] = (unsigned long) fn;
 261         regs.cp0_epc = (unsigned long) kernel_thread_helper;
 262         regs.cp0_status = read_c0_status();
 263 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 264         regs.cp0_status &= ~(ST0_KUP | ST0_IEC);
 265         regs.cp0_status |= ST0_IEP;
 266 #else
 267         regs.cp0_status |= ST0_EXL;
 268 #endif
 269
 270         /* Ok, create the new process.. */
 271         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 272 }
 273
 274 static struct mips_frame_info {
 275         void *func;
 276         int omit_fp;    /* compiled without fno-omit-frame-pointer */
 277         int frame_offset;
 278         int pc_offset;
 279 } schedule_frame, mfinfo[] = {
 280         { schedule, 0 },        /* must be first */
 281         /* arch/mips/kernel/semaphore.c */
 282         { __down, 1 },
 283         { __down_interruptible, 1 },
 284         /* kernel/sched.c */
 285 #ifdef CONFIG_PREEMPT
 286         { preempt_schedule, 0 },
 287 #endif
 288         { wait_for_completion, 0 },
 289         { interruptible_sleep_on, 0 },
 290         { interruptible_sleep_on_timeout, 0 },
 291         { sleep_on, 0 },
 292         { sleep_on_timeout, 0 },
 293         { yield, 0 },
 294         { io_schedule, 0 },
 295         { io_schedule_timeout, 0 },
 296 #if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
 297         { __preempt_spin_lock, 0 },
 298         { __preempt_write_lock, 0 },
 299 #endif
 300         /* kernel/timer.c */
 301         { schedule_timeout, 1 },
 302 /*      { nanosleep_restart, 1 }, */
 303         /* lib/rwsem-spinlock.c */
 304         { __down_read, 1 },
 305         { __down_write, 1 },
 306 };
 307
 308 static int mips_frame_info_initialized;
 309 static int __init get_frame_info(struct mips_frame_info *info)
 310 {
 311         int i;
 312         void *func = info->func;
 313         union mips_instruction *ip = (union mips_instruction *)func;
 314         info->pc_offset = -1;
 315         info->frame_offset = info->omit_fp ? 0 : -1;
 316         for (i = 0; i < 128; i++, ip++) {
 317                 /* if jal, jalr, jr, stop. */
 318                 if (ip->j_format.opcode == jal_op ||
 319                     (ip->r_format.opcode == spec_op &&
 320                      (ip->r_format.func == jalr_op ||
 321                       ip->r_format.func == jr_op)))
 322                         break;
 323
 324                 if (
 325 #ifdef CONFIG_32BIT
 326                     ip->i_format.opcode == sw_op &&
 327 #endif
 328 #ifdef CONFIG_64BIT
 329                     ip->i_format.opcode == sd_op &&
 330 #endif
 331                     ip->i_format.rs == 29)
 332                 {
 333                         /* sw / sd $ra, offset($sp) */
 334                         if (ip->i_format.rt == 31) {
 335                                 if (info->pc_offset != -1)
 336                                         continue;
 337                                 info->pc_offset =
 338                                         ip->i_format.simmediate / sizeof(long);
 339                         }
 340                         /* sw / sd $s8, offset($sp) */
 341                         if (ip->i_format.rt == 30) {
 342 //#if 0 /* gcc 3.4 does aggressive optimization... */
 343                                 if (info->frame_offset != -1)
 344                                         continue;
 345 //#endif
 346                                 info->frame_offset =
 347                                         ip->i_format.simmediate / sizeof(long);
 348                         }
 349                 }
 350         }
 351         if (info->pc_offset == -1 || info->frame_offset == -1) {
 352                 printk("Can't analyze prologue code at %p\n", func);
 353                 info->pc_offset = -1;
 354                 info->frame_offset = -1;
 355                 return -1;
 356         }
 357
 358         return 0;
 359 }
 360
 361 static int __init frame_info_init(void)
 362 {
 363         int i, found;
 364         for (i = 0; i < ARRAY_SIZE(mfinfo); i++)
 365                 if (get_frame_info(&mfinfo[i]))
 366                         return -1;
 367         schedule_frame = mfinfo[0];
 368         /* bubble sort */
 369         do {
 370                 struct mips_frame_info tmp;
 371                 found = 0;
 372                 for (i = 1; i < ARRAY_SIZE(mfinfo); i++) {
 373                         if (mfinfo[i-1].func > mfinfo[i].func) {
 374                                 tmp = mfinfo[i];
 375                                 mfinfo[i] = mfinfo[i-1];
 376                                 mfinfo[i-1] = tmp;
 377                                 found = 1;
 378                         }
 379                 }
 380         } while (found);
 381         mips_frame_info_initialized = 1;
 382         return 0;
 383 }
 384
 385 arch_initcall(frame_info_init);
 386
 387 /*
 388  * Return saved PC of a blocked thread.
 389  */
 390 unsigned long thread_saved_pc(struct task_struct *tsk)
 391 {
 392         struct thread_struct *t = &tsk->thread;
 393
 394         /* New born processes are a special case */
 395         if (t->reg31 == (unsigned long) ret_from_fork)
 396                 return t->reg31;
 397
 398         if (schedule_frame.pc_offset < 0)
 399                 return 0;
 400         return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
 401 }
 402
 403 /* get_wchan - a maintenance nightmare^W^Wpain in the ass ...  */
 404 unsigned long get_wchan(struct task_struct *p)
 405 {
 406         unsigned long stack_page;
 407         unsigned long frame, pc;
 408
 409         if (!p || p == current || p->state == TASK_RUNNING)
 410                 return 0;
 411
 412         stack_page = (unsigned long)p->thread_info;
 413         if (!stack_page || !mips_frame_info_initialized)
 414                 return 0;
 415
 416         pc = thread_saved_pc(p);
 417         if (!in_sched_functions(pc))
 418                 return pc;
 419
 420         frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
 421         do {
 422                 int i;
 423
 424                 if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32)
 425                         return 0;
 426
 427                 for (i = ARRAY_SIZE(mfinfo) - 1; i >= 0; i--) {
 428                         if (pc >= (unsigned long) mfinfo[i].func)
 429                                 break;
 430                 }
 431                 if (i < 0)
 432                         break;
 433
 434                 if (mfinfo[i].omit_fp)
 435                         break;
 436                 pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
 437                 frame = ((unsigned long *)frame)[mfinfo[i].frame_offset];
 438         } while (in_sched_functions(pc));
 439
 440         return pc;
 441 }
 442
 443 EXPORT_SYMBOL(get_wchan);