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/bootinfo.h>
  29 #include <asm/cpu.h>
  30 #include <asm/fpu.h>
  31 #include <asm/pgtable.h>
  32 #include <asm/system.h>
  33 #include <asm/mipsregs.h>
  34 #include <asm/processor.h>
  35 #include <asm/uaccess.h>
  36 #include <asm/io.h>
  37 #include <asm/elf.h>
  38 #include <asm/isadep.h>
  39 #include <asm/inst.h>
  40
  41 /*
  42  * We use this if we don't have any better idle routine..
  43  * (This to kill: kernel/platform.c.
  44  */
  45 void default_idle (void)
  46 {
  47 }
  48
  49 /*
  50  * The idle thread. There's no useful work to be done, so just try to conserve
  51  * power and have a low exit latency (ie sit in a loop waiting for somebody to
  52  * say that they'd like to reschedule)
  53  */
  54 ATTRIB_NORET void cpu_idle(void)
  55 {
  56         /* endless idle loop with no priority at all */
  57         while (1) {
  58                 while (!need_resched())
  59                         if (cpu_wait)
  60                                 (*cpu_wait)();
  61                 schedule();
  62         }
  63 }
  64
  65 asmlinkage void ret_from_fork(void);
  66
  67 void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
  68 {
  69         unsigned long status;
  70
  71         /* New thread loses kernel privileges. */
  72         status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK);
  73 #ifdef CONFIG_MIPS64
  74         status &= ~ST0_FR;
  75         status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
  76 #endif
  77         status |= KU_USER;
  78         regs->cp0_status = status;
  79         clear_used_math();
  80         lose_fpu();
  81         regs->cp0_epc = pc;
  82         regs->regs[29] = sp;
  83         current_thread_info()->addr_limit = USER_DS;
  84 }
  85
  86 void exit_thread(void)
  87 {
  88 }
  89
  90 void flush_thread(void)
  91 {
  92 }
  93
  94 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
  95         unsigned long unused, struct task_struct *p, struct pt_regs *regs)
  96 {
  97         struct thread_info *ti = p->thread_info;
  98         struct pt_regs *childregs;
  99         long childksp;
 100
 101         childksp = (unsigned long)ti + THREAD_SIZE - 32;
 102
 103         preempt_disable();
 104
 105         if (is_fpu_owner()) {
 106                 save_fp(p);
 107         }
 108
 109         preempt_enable();
 110
 111         /* set up new TSS. */
 112         childregs = (struct pt_regs *) childksp - 1;
 113         *childregs = *regs;
 114         childregs->regs[7] = 0; /* Clear error flag */
 115
 116 #if defined(CONFIG_BINFMT_IRIX)
 117         if (current->personality != PER_LINUX) {
 118                 /* Under IRIX things are a little different. */
 119                 childregs->regs[3] = 1;
 120                 regs->regs[3] = 0;
 121         }
 122 #endif
 123         childregs->regs[2] = 0; /* Child gets zero as return value */
 124         regs->regs[2] = p->pid;
 125
 126         if (childregs->cp0_status & ST0_CU0) {
 127                 childregs->regs[28] = (unsigned long) ti;
 128                 childregs->regs[29] = childksp;
 129                 ti->addr_limit = KERNEL_DS;
 130         } else {
 131                 childregs->regs[29] = usp;
 132                 ti->addr_limit = USER_DS;
 133         }
 134         p->thread.reg29 = (unsigned long) childregs;
 135         p->thread.reg31 = (unsigned long) ret_from_fork;
 136
 137         /*
 138          * New tasks lose permission to use the fpu. This accelerates context
 139          * switching for most programs since they don't use the fpu.
 140          */
 141         p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
 142         childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
 143         clear_tsk_thread_flag(p, TIF_USEDFPU);
 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
 153         return 1;
 154 }
 155
 156 void dump_regs(elf_greg_t *gp, struct pt_regs *regs)
 157 {
 158         int i;
 159
 160         for (i = 0; i < EF_R0; i++)
 161                 gp[i] = 0;
 162         gp[EF_R0] = 0;
 163         for (i = 1; i <= 31; i++)
 164                 gp[EF_R0 + i] = regs->regs[i];
 165         gp[EF_R26] = 0;
 166         gp[EF_R27] = 0;
 167         gp[EF_LO] = regs->lo;
 168         gp[EF_HI] = regs->hi;
 169         gp[EF_CP0_EPC] = regs->cp0_epc;
 170         gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
 171         gp[EF_CP0_STATUS] = regs->cp0_status;
 172         gp[EF_CP0_CAUSE] = regs->cp0_cause;
 173 #ifdef EF_UNUSED0
 174         gp[EF_UNUSED0] = 0;
 175 #endif
 176 }
 177
 178 int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr)
 179 {
 180         memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
 181
 182         return 1;
 183 }
 184
 185 /*
 186  * Create a kernel thread
 187  */
 188 ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
 189 {
 190         do_exit(fn(arg));
 191 }
 192
 193 long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 194 {
 195         struct pt_regs regs;
 196
 197         memset(&regs, 0, sizeof(regs));
 198
 199         regs.regs[4] = (unsigned long) arg;
 200         regs.regs[5] = (unsigned long) fn;
 201         regs.cp0_epc = (unsigned long) kernel_thread_helper;
 202         regs.cp0_status = read_c0_status();
 203 #if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
 204         regs.cp0_status &= ~(ST0_KUP | ST0_IEC);
 205         regs.cp0_status |= ST0_IEP;
 206 #else
 207         regs.cp0_status |= ST0_EXL;
 208 #endif
 209
 210         /* Ok, create the new process.. */
 211         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 212 }
 213
 214 struct mips_frame_info {
 215         int frame_offset;
 216         int pc_offset;
 217 };
 218 static struct mips_frame_info schedule_frame;
 219 static struct mips_frame_info schedule_timeout_frame;
 220 static struct mips_frame_info sleep_on_frame;
 221 static struct mips_frame_info sleep_on_timeout_frame;
 222 static struct mips_frame_info wait_for_completion_frame;
 223 static int mips_frame_info_initialized;
 224 static int __init get_frame_info(struct mips_frame_info *info, void *func)
 225 {
 226         int i;
 227         union mips_instruction *ip = (union mips_instruction *)func;
 228         info->pc_offset = -1;
 229         info->frame_offset = -1;
 230         for (i = 0; i < 128; i++, ip++) {
 231                 /* if jal, jalr, jr, stop. */
 232                 if (ip->j_format.opcode == jal_op ||
 233                     (ip->r_format.opcode == spec_op &&
 234                      (ip->r_format.func == jalr_op ||
 235                       ip->r_format.func == jr_op)))
 236                         break;
 237
 238                 if (
 239 #ifdef CONFIG_MIPS32
 240                     ip->i_format.opcode == sw_op &&
 241 #endif
 242 #ifdef CONFIG_MIPS64
 243                     ip->i_format.opcode == sd_op &&
 244 #endif
 245                     ip->i_format.rs == 29)
 246                 {
 247                         /* sw / sd $ra, offset($sp) */
 248                         if (ip->i_format.rt == 31) {
 249                                 if (info->pc_offset != -1)
 250                                         break;
 251                                 info->pc_offset =
 252                                         ip->i_format.simmediate / sizeof(long);
 253                         }
 254                         /* sw / sd $s8, offset($sp) */
 255                         if (ip->i_format.rt == 30) {
 256                                 if (info->frame_offset != -1)
 257                                         break;
 258                                 info->frame_offset =
 259                                         ip->i_format.simmediate / sizeof(long);
 260                         }
 261                 }
 262         }
 263         if (info->pc_offset == -1 || info->frame_offset == -1) {
 264                 printk("Can't analyze prologue code at %p\n", func);
 265                 info->pc_offset = -1;
 266                 info->frame_offset = -1;
 267                 return -1;
 268         }
 269
 270         return 0;
 271 }
 272
 273 static int __init frame_info_init(void)
 274 {
 275         mips_frame_info_initialized =
 276                 !get_frame_info(&schedule_frame, schedule) &&
 277                 !get_frame_info(&schedule_timeout_frame, schedule_timeout) &&
 278                 !get_frame_info(&sleep_on_frame, sleep_on) &&
 279                 !get_frame_info(&sleep_on_timeout_frame, sleep_on_timeout) &&
 280                 !get_frame_info(&wait_for_completion_frame, wait_for_completion);
 281
 282         return 0;
 283 }
 284
 285 arch_initcall(frame_info_init);
 286
 287 /*
 288  * Return saved PC of a blocked thread.
 289  */
 290 unsigned long thread_saved_pc(struct task_struct *tsk)
 291 {
 292         struct thread_struct *t = &tsk->thread;
 293
 294         /* New born processes are a special case */
 295         if (t->reg31 == (unsigned long) ret_from_fork)
 296                 return t->reg31;
 297
 298         if (schedule_frame.pc_offset < 0)
 299                 return 0;
 300         return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
 301 }
 302
 303 /* get_wchan - a maintenance nightmare^W^Wpain in the ass ...  */
 304 unsigned long get_wchan(struct task_struct *p)
 305 {
 306         unsigned long frame, pc;
 307
 308         if (!p || p == current || p->state == TASK_RUNNING)
 309                 return 0;
 310
 311         if (!mips_frame_info_initialized)
 312                 return 0;
 313         pc = thread_saved_pc(p);
 314         if (!in_sched_functions(pc))
 315                 goto out;
 316
 317         if (pc >= (unsigned long) sleep_on_timeout)
 318                 goto schedule_timeout_caller;
 319         if (pc >= (unsigned long) sleep_on)
 320                 goto schedule_caller;
 321         if (pc >= (unsigned long) interruptible_sleep_on_timeout)
 322                 goto schedule_timeout_caller;
 323         if (pc >= (unsigned long)interruptible_sleep_on)
 324                 goto schedule_caller;
 325         if (pc >= (unsigned long)wait_for_completion)
 326                 goto schedule_caller;
 327         goto schedule_timeout_caller;
 328
 329 schedule_caller:
 330         frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
 331         if (pc >= (unsigned long) sleep_on)
 332                 pc = ((unsigned long *)frame)[sleep_on_frame.pc_offset];
 333         else
 334                 pc = ((unsigned long *)frame)[wait_for_completion_frame.pc_offset];
 335         goto out;
 336
 337 schedule_timeout_caller:
 338         /*
 339          * The schedule_timeout frame
 340          */
 341         frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
 342
 343         /*
 344          * frame now points to sleep_on_timeout's frame
 345          */
 346         pc    = ((unsigned long *)frame)[schedule_timeout_frame.pc_offset];
 347
 348         if (in_sched_functions(pc)) {
 349                 /* schedule_timeout called by [interruptible_]sleep_on_timeout */
 350                 frame = ((unsigned long *)frame)[schedule_timeout_frame.frame_offset];
 351                 pc    = ((unsigned long *)frame)[sleep_on_timeout_frame.pc_offset];
 352         }
 353
 354 out:
 355
 356 #ifdef CONFIG_MIPS64
 357         if (current->thread.mflags & MF_32BIT_REGS) /* Kludge for 32-bit ps  */
 358                 pc &= 0xffffffffUL;
 359 #endif
 360
 361         return pc;
 362 }
 363
 364 EXPORT_SYMBOL(get_wchan);