arch/mips64/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/errno.h>
  10 #include <linux/sched.h>
  11 #include <linux/kernel.h>
  12 #include <linux/mm.h>
  13 #include <linux/stddef.h>
  14 #include <linux/unistd.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/slab.h>
  17 #include <linux/mman.h>
  18 #include <linux/personality.h>
  19 #include <linux/sys.h>
  20 #include <linux/user.h>
  21 #include <linux/a.out.h>
  22 #include <linux/init.h>
  23 #include <linux/completion.h>
  24
  25 #include <asm/bootinfo.h>
  26 #include <asm/pgtable.h>
  27 #include <asm/system.h>
  28 #include <asm/mipsregs.h>
  29 #include <asm/processor.h>
  30 #include <asm/stackframe.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/io.h>
  33 #include <asm/elf.h>
  34 #include <asm/cpu.h>
  35 #include <asm/fpu.h>
  36 #include <asm/inst.h>
  37
  38 /*
  39  * We use this if we don't have any better idle routine..
  40  * (This to kill: kernel/platform.c.
  41  */
  42 void default_idle (void)
  43 {
  44 }
  45
  46 /*
  47  * The idle thread. There's no useful work to be done, so just try to conserve
  48  * power and have a low exit latency (ie sit in a loop waiting for somebody to
  49  * say that they'd like to reschedule)
  50  */
  51 ATTRIB_NORET void cpu_idle(void)
  52 {
  53         /* endless idle loop with no priority at all */
  54         while (1) {
  55                 while (!need_resched())
  56                         if (cpu_wait)
  57                                 (*cpu_wait)();
  58                 schedule();
  59         }
  60 }
  61
  62 asmlinkage void ret_from_fork(void);
  63
  64 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  65 {
  66         unsigned long status;
  67
  68         /* New thread loses kernel privileges. */
  69         status = regs->cp0_status & ~(ST0_CU0|ST0_FR|ST0_KSU);
  70         status |= KSU_USER;
  71         status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
  72         regs->cp0_status = status;
  73         current->used_math = 0;
  74         loose_fpu();
  75         regs->cp0_epc = pc;
  76         regs->regs[29] = sp;
  77         current_thread_info()->addr_limit = USER_DS;
  78 }
  79
  80 void exit_thread(void)
  81 {
  82 }
  83
  84 void flush_thread(void)
  85 {
  86 }
  87
  88 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
  89                 unsigned long unused, struct task_struct *p,
  90                 struct pt_regs *regs)
  91 {
  92         struct thread_info *ti = p->thread_info;
  93         struct pt_regs *childregs;
  94         long childksp;
  95
  96         childksp = (unsigned long)ti + KERNEL_STACK_SIZE - 32;
  97
  98         if (is_fpu_owner()) {
  99                 save_fp(p);
 100         }
 101
 102         /* set up new TSS. */
 103         childregs = (struct pt_regs *) childksp - 1;
 104         *childregs = *regs;
 105         childregs->regs[7] = 0; /* Clear error flag */
 106         childregs->regs[2] = 0; /* Child gets zero as return value */
 107         regs->regs[2] = p->pid;
 108
 109         if (childregs->cp0_status & ST0_CU0) {
 110                 childregs->regs[28] = (unsigned long) ti;
 111                 childregs->regs[29] = childksp;
 112                 ti->addr_limit = KERNEL_DS;
 113         } else {
 114                 childregs->regs[29] = usp;
 115                 ti->addr_limit = USER_DS;
 116         }
 117         p->thread.reg29 = (unsigned long) childregs;
 118         p->thread.reg31 = (unsigned long) ret_from_fork;
 119
 120         /*
 121          * New tasks lose permission to use the fpu. This accelerates context
 122          * switching for most programs since they don't use the fpu.
 123          */
 124         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1|ST0_KSU);
 125         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 126         clear_tsk_thread_flag(p, TIF_USEDFPU);
 127         p->set_child_tid = p->clear_child_tid = NULL;
 128
 129         return 0;
 130 }
 131
 132 /* Fill in the fpu structure for a core dump.. */
 133 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 134 {
 135         memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
 136         return 1;
 137 }
 138
 139 /*
 140  * Create a kernel thread
 141  */
 142 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 143 {
 144         int retval;
 145
 146         __asm__ __volatile__(
 147                 "       move    $6, $sp         \n"
 148                 "       move    $4, %5          \n"
 149                 "       li      $2, %1          \n"
 150                 "       syscall                 \n"
 151                 "       beq     $6, $sp, 1f     \n"
 152                 "       move    $4, %3          \n"
 153                 "       jalr    %4              \n"
 154                 "       move    $4, $2          \n"
 155                 "       li      $2, %2          \n"
 156                 "       syscall                 \n"
 157                 "1:     move    %0, $2"
 158                 : "=r" (retval)
 159                 : "i" (__NR_clone), "i" (__NR_exit), "r" (arg), "r" (fn),
 160                   "r" (flags | CLONE_VM | CLONE_UNTRACED)
 161                  /*
 162                   * The called subroutine might have destroyed any of the
 163                   * at, result, argument or temporary registers ...
 164                   */
 165                 : "$2", "$3", "$4", "$5", "$6", "$7", "$8",
 166                   "$9","$10","$11","$12","$13","$14","$15","$24","$25","$31");
 167
 168         return retval;
 169 }
 170
 171 struct mips_frame_info {
 172         int frame_offset;
 173         int pc_offset;
 174 };
 175 static struct mips_frame_info schedule_frame;
 176 static struct mips_frame_info schedule_timeout_frame;
 177 static struct mips_frame_info sleep_on_frame;
 178 static struct mips_frame_info sleep_on_timeout_frame;
 179 static struct mips_frame_info wait_for_completion_frame;
 180 static int mips_frame_info_initialized;
 181 static int __init get_frame_info(struct mips_frame_info *info, void *func)
 182 {
 183         int i;
 184         union mips_instruction *ip = (union mips_instruction *)func;
 185         info->pc_offset = -1;
 186         info->frame_offset = -1;
 187         for (i = 0; i < 128; i++, ip++) {
 188                 /* if jal, jalr, jr, stop. */
 189                 if (ip->j_format.opcode == jal_op ||
 190                     (ip->r_format.opcode == spec_op &&
 191                      (ip->r_format.func == jalr_op ||
 192                       ip->r_format.func == jr_op)))
 193                         break;
 194                 if (ip->i_format.opcode == sd_op &&
 195                     ip->i_format.rs == 29) {
 196                         /* sd $ra, offset($sp) */
 197                         if (ip->i_format.rt == 31) {
 198                                 if (info->pc_offset != -1)
 199                                         break;
 200                                 info->pc_offset =
 201                                         ip->i_format.simmediate / sizeof(long);
 202                         }
 203                         /* sd $s8, offset($sp) */
 204                         if (ip->i_format.rt == 30) {
 205                                 if (info->frame_offset != -1)
 206                                         break;
 207                                 info->frame_offset =
 208                                         ip->i_format.simmediate / sizeof(long);
 209                         }
 210                 }
 211         }
 212         if (info->pc_offset == -1 || info->frame_offset == -1) {
 213                 printk("Can't analyze prologue code at %p\n", func);
 214                 info->pc_offset = -1;
 215                 info->frame_offset = -1;
 216                 return -1;
 217         }
 218
 219         return 0;
 220 }
 221 void __init frame_info_init(void)
 222 {
 223         mips_frame_info_initialized =
 224                 !get_frame_info(&schedule_frame, schedule) &&
 225                 !get_frame_info(&schedule_timeout_frame, schedule_timeout) &&
 226                 !get_frame_info(&sleep_on_frame, sleep_on) &&
 227                 !get_frame_info(&sleep_on_timeout_frame, sleep_on_timeout) &&
 228                 !get_frame_info(&wait_for_completion_frame, wait_for_completion);
 229 }
 230
 231 /*
 232  * Return saved PC of a blocked thread.
 233  */
 234 unsigned long thread_saved_pc(struct thread_struct *t)
 235 {
 236         extern void ret_from_fork(void);
 237
 238         /* New born processes are a special case */
 239         if (t->reg31 == (unsigned long) ret_from_fork)
 240                 return t->reg31;
 241
 242         if (schedule_frame.pc_offset < 0)
 243                 return 0;
 244         return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
 245 }
 246
 247 /*
 248  * These bracket the sleeping functions..
 249  */
 250 extern void scheduling_functions_start_here(void);
 251 extern void scheduling_functions_end_here(void);
 252 #define first_sched     ((unsigned long) scheduling_functions_start_here)
 253 #define last_sched      ((unsigned long) scheduling_functions_end_here)
 254
 255 /* get_wchan - a maintenance nightmare ...  */
 256 unsigned long get_wchan(struct task_struct *p)
 257 {
 258         unsigned long frame, pc;
 259
 260         if (!p || p == current || p->state == TASK_RUNNING)
 261                 return 0;
 262
 263         if (!mips_frame_info_initialized)
 264                 return 0;
 265         pc = thread_saved_pc(&p->thread);
 266         if (pc < first_sched || pc >= last_sched)
 267                 goto out;
 268
 269         if (pc >= (unsigned long) sleep_on_timeout)
 270                 goto schedule_timeout_caller;
 271         if (pc >= (unsigned long) sleep_on)
 272                 goto schedule_caller;
 273         if (pc >= (unsigned long) interruptible_sleep_on_timeout)
 274                 goto schedule_timeout_caller;
 275         if (pc >= (unsigned long)interruptible_sleep_on)
 276                 goto schedule_caller;
 277         if (pc >= (unsigned long)wait_for_completion)
 278                 goto schedule_caller;
 279         goto schedule_timeout_caller;
 280
 281 schedule_caller:
 282         frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
 283         if (pc >= (unsigned long) sleep_on)
 284                 pc = ((unsigned long *)frame)[sleep_on_frame.pc_offset];
 285         else
 286                 pc = ((unsigned long *)frame)[wait_for_completion_frame.pc_offset];
 287         goto out;
 288
 289 schedule_timeout_caller:
 290         /* Must be schedule_timeout ...  */
 291         frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
 292
 293         /* The schedule_timeout frame ...  */
 294         pc    = ((unsigned long *)frame)[schedule_timeout_frame.pc_offset];
 295
 296         if (pc >= first_sched && pc < last_sched) {
 297                 /* schedule_timeout called by [interruptible_]sleep_on_timeout */
 298                 frame = ((unsigned long *)frame)[schedule_timeout_frame.frame_offset];
 299                 pc    = ((unsigned long *)frame)[sleep_on_timeout_frame.pc_offset];
 300         }
 301
 302 out:
 303         if (current->thread.mflags & MF_32BIT_REGS) /* Kludge for 32-bit ps  */
 304                 pc &= 0xffffffff;
 305
 306         return pc;
 307 }