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  */
   9 #include <linux/config.h>
  10 #include <linux/errno.h>
  11 #include <linux/module.h>
  12 #include <linux/sched.h>
  13 #include <linux/kernel.h>
  14 #include <linux/mm.h>
  15 #include <linux/stddef.h>
  16 #include <linux/unistd.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/slab.h>
  19 #include <linux/mman.h>
  20 #include <linux/personality.h>
  21 #include <linux/sys.h>
  22 #include <linux/user.h>
  23 #include <linux/a.out.h>
  24 #include <linux/init.h>
  25 #include <linux/completion.h>
  26
  27 #include <asm/bootinfo.h>
  28 #include <asm/cpu.h>
  29 #include <asm/fpu.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/system.h>
  32 #include <asm/mipsregs.h>
  33 #include <asm/processor.h>
  34 #include <asm/uaccess.h>
  35 #include <asm/io.h>
  36 #include <asm/elf.h>
  37 #include <asm/isadep.h>
  38 #include <asm/inst.h>
  39
  40 /*
  41  * We use this if we don't have any better idle routine..
  42  * (This to kill: kernel/platform.c.
  43  */
  44 void default_idle (void)
  45 {
  46 }
  47
  48 /*
  49  * The idle thread. There's no useful work to be done, so just try to conserve
  50  * power and have a low exit latency (ie sit in a loop waiting for somebody to
  51  * say that they'd like to reschedule)
  52  */
  53 ATTRIB_NORET void cpu_idle(void)
  54 {
  55         /* endless idle loop with no priority at all */
  56         while (1) {
  57                 while (!need_resched())
  58                         if (cpu_wait)
  59                                 (*cpu_wait)();
  60                 schedule();
  61         }
  62 }
  63
  64 asmlinkage void ret_from_fork(void);
  65
  66 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  67 {
  68         unsigned long status;
  69
  70         /* New thread loses kernel privileges. */
  71         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK);
  72 #ifdef CONFIG_MIPS64
  73         status &= ~ST0_FR;
  74         status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
  75 #endif
  76         status |= KU_USER;
  77         regs->cp0_status = status;
  78         current->used_math = 0;
  79         lose_fpu();
  80         regs->cp0_epc = pc;
  81         regs->regs[29] = sp;
  82         current_thread_info()->addr_limit = USER_DS;
  83 }
  84
  85 void exit_thread(void)
  86 {
  87 }
  88
  89 void flush_thread(void)
  90 {
  91 }
  92
  93 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
  94         unsigned long unused, struct task_struct *p, struct pt_regs *regs)
  95 {
  96         struct thread_info *ti = p->thread_info;
  97         struct pt_regs *childregs;
  98         long childksp;
  99
 100         childksp = (unsigned long)ti + THREAD_SIZE - 32;
 101
 102         if (is_fpu_owner()) {
 103                 save_fp(p);
 104         }
 105
 106         /* set up new TSS. */
 107         childregs = (struct pt_regs *) childksp - 1;
 108         *childregs = *regs;
 109         childregs->regs[7] = 0; /* Clear error flag */
 110
 111 #ifdef CONFIG_BINFMT_IRIX
 112         if (current->personality != PER_LINUX) {
 113                 /* Under IRIX things are a little different. */
 114                 childregs->regs[2] = 0;
 115                 childregs->regs[3] = 1;
 116                 regs->regs[2] = p->pid;
 117                 regs->regs[3] = 0;
 118         } else
 119 #endif
 120         {
 121                 childregs->regs[2] = 0; /* Child gets zero as return value */
 122                 regs->regs[2] = p->pid;
 123         }
 124
 125         if (childregs->cp0_status & ST0_CU0) {
 126                 childregs->regs[28] = (unsigned long) ti;
 127                 childregs->regs[29] = childksp;
 128                 ti->addr_limit = KERNEL_DS;
 129         } else {
 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         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 141         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 142         clear_tsk_thread_flag(p, TIF_USEDFPU);
 143         p->set_child_tid = p->clear_child_tid = NULL;
 144
 145         return 0;
 146 }
 147
 148 /* Fill in the fpu structure for a core dump.. */
 149 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 150 {
 151         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
 152         return 1;
 153 }
 154
 155 /*
 156  * Create a kernel thread
 157  */
 158 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 159 {
 160         long retval;
 161
 162         __asm__ __volatile__(
 163                 "       move    $6, $sp         \n"
 164                 "       move    $4, %5          \n"
 165                 "       li      $2, %1          \n"
 166                 "       syscall                 \n"
 167                 "       beq     $6, $sp, 1f     \n"
 168 #ifdef CONFIG_MIPS32    /* On o32 the caller has to create the stackframe */
 169                 "       subu    $sp, 32         \n"
 170 #endif
 171                 "       move    $4, %3          \n"
 172                 "       jalr    %4              \n"
 173                 "       move    $4, $2          \n"
 174                 "       li      $2, %2          \n"
 175                 "       syscall                 \n"
 176 #ifdef CONFIG_MIPS32    /* On o32 the caller has to deallocate the stackframe */
 177                 "       addiu   $sp, 32         \n"
 178 #endif
 179                 "1:     move    %0, $2"
 180                 : "=r" (retval)
 181                 : "i" (__NR_clone), "i" (__NR_exit), "r" (arg), "r" (fn),
 182                   "r" (flags | CLONE_VM | CLONE_UNTRACED)
 183                  /*
 184                   * The called subroutine might have destroyed any of the
 185                   * at, result, argument or temporary registers ...
 186                   */
 187                 : "$2", "$3", "$4", "$5", "$6", "$7", "$8",
 188                   "$9","$10","$11","$12","$13","$14","$15","$24","$25","$31");
 189
 190         return retval;
 191 }
 192
 193 struct mips_frame_info {
 194         int frame_offset;
 195         int pc_offset;
 196 };
 197 static struct mips_frame_info schedule_frame;
 198 static struct mips_frame_info schedule_timeout_frame;
 199 static struct mips_frame_info sleep_on_frame;
 200 static struct mips_frame_info sleep_on_timeout_frame;
 201 static struct mips_frame_info wait_for_completion_frame;
 202 static int mips_frame_info_initialized;
 203 static int __init get_frame_info(struct mips_frame_info *info, void *func)
 204 {
 205         int i;
 206         union mips_instruction *ip = (union mips_instruction *)func;
 207         info->pc_offset = -1;
 208         info->frame_offset = -1;
 209         for (i = 0; i < 128; i++, ip++) {
 210                 /* if jal, jalr, jr, stop. */
 211                 if (ip->j_format.opcode == jal_op ||
 212                     (ip->r_format.opcode == spec_op &&
 213                      (ip->r_format.func == jalr_op ||
 214                       ip->r_format.func == jr_op)))
 215                         break;
 216
 217                 if (
 218 #ifdef CONFIG_MIPS32
 219                     ip->i_format.opcode == sw_op &&
 220 #endif
 221 #ifdef CONFIG_MIPS64
 222                     ip->i_format.opcode == sd_op &&
 223 #endif
 224                     ip->i_format.rs == 29)
 225                 {
 226                         /* sw / sd $ra, offset($sp) */
 227                         if (ip->i_format.rt == 31) {
 228                                 if (info->pc_offset != -1)
 229                                         break;
 230                                 info->pc_offset =
 231                                         ip->i_format.simmediate / sizeof(long);
 232                         }
 233                         /* sw / sd $s8, offset($sp) */
 234                         if (ip->i_format.rt == 30) {
 235                                 if (info->frame_offset != -1)
 236                                         break;
 237                                 info->frame_offset =
 238                                         ip->i_format.simmediate / sizeof(long);
 239                         }
 240                 }
 241         }
 242         if (info->pc_offset == -1 || info->frame_offset == -1) {
 243                 printk("Can't analyze prologue code at %p\n", func);
 244                 info->pc_offset = -1;
 245                 info->frame_offset = -1;
 246                 return -1;
 247         }
 248
 249         return 0;
 250 }
 251
 252 static int __init frame_info_init(void)
 253 {
 254         mips_frame_info_initialized =
 255                 !get_frame_info(&schedule_frame, schedule) &&
 256                 !get_frame_info(&schedule_timeout_frame, schedule_timeout) &&
 257                 !get_frame_info(&sleep_on_frame, sleep_on) &&
 258                 !get_frame_info(&sleep_on_timeout_frame, sleep_on_timeout) &&
 259                 !get_frame_info(&wait_for_completion_frame, wait_for_completion);
 260
 261         return 0;
 262 }
 263
 264 arch_initcall(frame_info_init);
 265
 266 /*
 267  * Return saved PC of a blocked thread.
 268  */
 269 unsigned long thread_saved_pc(struct task_struct *tsk)
 270 {
 271         extern void ret_from_fork(void);
 272         struct thread_struct *t = &tsk->thread;
 273
 274         /* New born processes are a special case */
 275         if (t->reg31 == (unsigned long) ret_from_fork)
 276                 return t->reg31;
 277
 278         if (schedule_frame.pc_offset < 0)
 279                 return 0;
 280         return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
 281 }
 282
 283 /* get_wchan - a maintenance nightmare^W^Wpain in the ass ...  */
 284 unsigned long get_wchan(struct task_struct *p)
 285 {
 286         unsigned long frame, pc;
 287
 288         if (!p || p == current || p->state == TASK_RUNNING)
 289                 return 0;
 290
 291         if (!mips_frame_info_initialized)
 292                 return 0;
 293         pc = thread_saved_pc(p);
 294         if (!in_sched_functions(pc))
 295                 goto out;
 296
 297         if (pc >= (unsigned long) sleep_on_timeout)
 298                 goto schedule_timeout_caller;
 299         if (pc >= (unsigned long) sleep_on)
 300                 goto schedule_caller;
 301         if (pc >= (unsigned long) interruptible_sleep_on_timeout)
 302                 goto schedule_timeout_caller;
 303         if (pc >= (unsigned long)interruptible_sleep_on)
 304                 goto schedule_caller;
 305         if (pc >= (unsigned long)wait_for_completion)
 306                 goto schedule_caller;
 307         goto schedule_timeout_caller;
 308
 309 schedule_caller:
 310         frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
 311         if (pc >= (unsigned long) sleep_on)
 312                 pc = ((unsigned long *)frame)[sleep_on_frame.pc_offset];
 313         else
 314                 pc = ((unsigned long *)frame)[wait_for_completion_frame.pc_offset];
 315         goto out;
 316
 317 schedule_timeout_caller:
 318         /*
 319          * The schedule_timeout frame
 320          */
 321         frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
 322
 323         /*
 324          * frame now points to sleep_on_timeout's frame
 325          */
 326         pc    = ((unsigned long *)frame)[schedule_timeout_frame.pc_offset];
 327
 328         if (in_sched_functions(pc)) {
 329                 /* schedule_timeout called by [interruptible_]sleep_on_timeout */
 330                 frame = ((unsigned long *)frame)[schedule_timeout_frame.frame_offset];
 331                 pc    = ((unsigned long *)frame)[sleep_on_timeout_frame.pc_offset];
 332         }
 333
 334 out:
 335
 336 #ifdef CONFIG_MIPS64
 337         if (current->thread.mflags & MF_32BIT_REGS) /* Kludge for 32-bit ps  */
 338                 pc &= 0xffffffffUL;
 339 #endif
 340
 341         return pc;
 342 }
 343
 344 EXPORT_SYMBOL(get_wchan);