arch/mn10300/kernel/process.c

   1 /* MN10300  Process handling code
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #include <linux/module.h>
  12 #include <linux/errno.h>
  13 #include <linux/sched.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mm.h>
  16 #include <linux/smp.h>
  17 #include <linux/smp_lock.h>
  18 #include <linux/stddef.h>
  19 #include <linux/unistd.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/user.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/delay.h>
  24 #include <linux/reboot.h>
  25 #include <linux/percpu.h>
  26 #include <linux/err.h>
  27 #include <linux/fs.h>
  28 #include <linux/slab.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/system.h>
  32 #include <asm/io.h>
  33 #include <asm/processor.h>
  34 #include <asm/mmu_context.h>
  35 #include <asm/fpu.h>
  36 #include <asm/reset-regs.h>
  37 #include <asm/gdb-stub.h>
  38 #include "internal.h"
  39
  40 /*
  41  * power management idle function, if any..
  42  */
  43 void (*pm_idle)(void);
  44 EXPORT_SYMBOL(pm_idle);
  45
  46 /*
  47  * return saved PC of a blocked thread.
  48  */
  49 unsigned long thread_saved_pc(struct task_struct *tsk)
  50 {
  51         return ((unsigned long *) tsk->thread.sp)[3];
  52 }
  53
  54 /*
  55  * power off function, if any
  56  */
  57 void (*pm_power_off)(void);
  58 EXPORT_SYMBOL(pm_power_off);
  59
  60 #if !defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
  61 /*
  62  * we use this if we don't have any better idle routine
  63  */
  64 static void default_idle(void)
  65 {
  66         local_irq_disable();
  67         if (!need_resched())
  68                 safe_halt();
  69         else
  70                 local_irq_enable();
  71 }
  72
  73 #else /* !CONFIG_SMP || CONFIG_HOTPLUG_CPU  */
  74 /*
  75  * On SMP it's slightly faster (but much more power-consuming!)
  76  * to poll the ->work.need_resched flag instead of waiting for the
  77  * cross-CPU IPI to arrive. Use this option with caution.
  78  */
  79 static inline void poll_idle(void)
  80 {
  81         int oldval;
  82
  83         local_irq_enable();
  84
  85         /*
  86          * Deal with another CPU just having chosen a thread to
  87          * run here:
  88          */
  89         oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
  90
  91         if (!oldval) {
  92                 set_thread_flag(TIF_POLLING_NRFLAG);
  93                 while (!need_resched())
  94                         cpu_relax();
  95                 clear_thread_flag(TIF_POLLING_NRFLAG);
  96         } else {
  97                 set_need_resched();
  98         }
  99 }
 100 #endif /* !CONFIG_SMP || CONFIG_HOTPLUG_CPU */
 101
 102 /*
 103  * the idle thread
 104  * - there's no useful work to be done, so just try to conserve power and have
 105  *   a low exit latency (ie sit in a loop waiting for somebody to say that
 106  *   they'd like to reschedule)
 107  */
 108 void cpu_idle(void)
 109 {
 110         /* endless idle loop with no priority at all */
 111         for (;;) {
 112                 while (!need_resched()) {
 113                         void (*idle)(void);
 114
 115                         smp_rmb();
 116                         idle = pm_idle;
 117                         if (!idle) {
 118 #if defined(CONFIG_SMP) && !defined(CONFIG_HOTPLUG_CPU)
 119                                 idle = poll_idle;
 120 #else  /* CONFIG_SMP && !CONFIG_HOTPLUG_CPU */
 121                                 idle = default_idle;
 122 #endif /* CONFIG_SMP && !CONFIG_HOTPLUG_CPU */
 123                         }
 124                         idle();
 125                 }
 126
 127                 preempt_enable_no_resched();
 128                 schedule();
 129                 preempt_disable();
 130         }
 131 }
 132
 133 void release_segments(struct mm_struct *mm)
 134 {
 135 }
 136
 137 void machine_restart(char *cmd)
 138 {
 139 #ifdef CONFIG_GDBSTUB
 140         gdbstub_exit(0);
 141 #endif
 142
 143 #ifdef mn10300_unit_hard_reset
 144         mn10300_unit_hard_reset();
 145 #else
 146         mn10300_proc_hard_reset();
 147 #endif
 148 }
 149
 150 void machine_halt(void)
 151 {
 152 #ifdef CONFIG_GDBSTUB
 153         gdbstub_exit(0);
 154 #endif
 155 }
 156
 157 void machine_power_off(void)
 158 {
 159 #ifdef CONFIG_GDBSTUB
 160         gdbstub_exit(0);
 161 #endif
 162 }
 163
 164 void show_regs(struct pt_regs *regs)
 165 {
 166 }
 167
 168 /*
 169  * create a kernel thread
 170  */
 171 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 172 {
 173         struct pt_regs regs;
 174
 175         memset(&regs, 0, sizeof(regs));
 176
 177         regs.a2 = (unsigned long) fn;
 178         regs.d2 = (unsigned long) arg;
 179         regs.pc = (unsigned long) kernel_thread_helper;
 180         local_save_flags(regs.epsw);
 181         regs.epsw |= EPSW_IE | EPSW_IM_7;
 182
 183         /* Ok, create the new process.. */
 184         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0,
 185                        NULL, NULL);
 186 }
 187 EXPORT_SYMBOL(kernel_thread);
 188
 189 /*
 190  * free current thread data structures etc..
 191  */
 192 void exit_thread(void)
 193 {
 194         exit_fpu();
 195 }
 196
 197 void flush_thread(void)
 198 {
 199         flush_fpu();
 200 }
 201
 202 void release_thread(struct task_struct *dead_task)
 203 {
 204 }
 205
 206 /*
 207  * we do not have to muck with descriptors here, that is
 208  * done in switch_mm() as needed.
 209  */
 210 void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
 211 {
 212 }
 213
 214 /*
 215  * this gets called before we allocate a new thread and copy the current task
 216  * into it so that we can store lazy state into memory
 217  */
 218 void prepare_to_copy(struct task_struct *tsk)
 219 {
 220         unlazy_fpu(tsk);
 221 }
 222
 223 /*
 224  * set up the kernel stack for a new thread and copy arch-specific thread
 225  * control information
 226  */
 227 int copy_thread(unsigned long clone_flags,
 228                 unsigned long c_usp, unsigned long ustk_size,
 229                 struct task_struct *p, struct pt_regs *kregs)
 230 {
 231         struct pt_regs *c_uregs, *c_kregs, *uregs;
 232         unsigned long c_ksp;
 233
 234         uregs = current->thread.uregs;
 235
 236         c_ksp = (unsigned long) task_stack_page(p) + THREAD_SIZE;
 237
 238         /* allocate the userspace exception frame and set it up */
 239         c_ksp -= sizeof(struct pt_regs);
 240         c_uregs = (struct pt_regs *) c_ksp;
 241
 242         p->thread.uregs = c_uregs;
 243         *c_uregs = *uregs;
 244         c_uregs->sp = c_usp;
 245         c_uregs->epsw &= ~EPSW_FE; /* my FPU */
 246
 247         c_ksp -= 12; /* allocate function call ABI slack */
 248
 249         /* the new TLS pointer is passed in as arg #5 to sys_clone() */
 250         if (clone_flags & CLONE_SETTLS)
 251                 c_uregs->e2 = __frame->d3;
 252
 253         /* set up the return kernel frame if called from kernel_thread() */
 254         c_kregs = c_uregs;
 255         if (kregs != uregs) {
 256                 c_ksp -= sizeof(struct pt_regs);
 257                 c_kregs = (struct pt_regs *) c_ksp;
 258                 *c_kregs = *kregs;
 259                 c_kregs->sp = c_usp;
 260                 c_kregs->next = c_uregs;
 261 #ifdef CONFIG_MN10300_CURRENT_IN_E2
 262                 c_kregs->e2 = (unsigned long) p; /* current */
 263 #endif
 264
 265                 c_ksp -= 12; /* allocate function call ABI slack */
 266         }
 267
 268         /* set up things up so the scheduler can start the new task */
 269         p->thread.frame = c_kregs;
 270         p->thread.a3    = (unsigned long) c_kregs;
 271         p->thread.sp    = c_ksp;
 272         p->thread.pc    = (unsigned long) ret_from_fork;
 273         p->thread.wchan = (unsigned long) ret_from_fork;
 274         p->thread.usp   = c_usp;
 275
 276         return 0;
 277 }
 278
 279 /*
 280  * clone a process
 281  * - tlsptr is retrieved by copy_thread() from __frame->d3
 282  */
 283 asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp,
 284                           int __user *parent_tidptr, int __user *child_tidptr,
 285                           int __user *tlsptr)
 286 {
 287         return do_fork(clone_flags, newsp ?: __frame->sp, __frame, 0,
 288                        parent_tidptr, child_tidptr);
 289 }
 290
 291 asmlinkage long sys_fork(void)
 292 {
 293         return do_fork(SIGCHLD, __frame->sp, __frame, 0, NULL, NULL);
 294 }
 295
 296 asmlinkage long sys_vfork(void)
 297 {
 298         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, __frame->sp, __frame,
 299                        0, NULL, NULL);
 300 }
 301
 302 asmlinkage long sys_execve(const char __user *name,
 303                            const char __user *const __user *argv,
 304                            const char __user *const __user *envp)
 305 {
 306         char *filename;
 307         int error;
 308
 309         filename = getname(name);
 310         error = PTR_ERR(filename);
 311         if (IS_ERR(filename))
 312                 return error;
 313         error = do_execve(filename, argv, envp, __frame);
 314         putname(filename);
 315         return error;
 316 }
 317
 318 unsigned long get_wchan(struct task_struct *p)
 319 {
 320         return p->thread.wchan;
 321 }