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/stddef.h>
  18 #include <linux/unistd.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/user.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/delay.h>
  23 #include <linux/reboot.h>
  24 #include <linux/percpu.h>
  25 #include <linux/err.h>
  26 #include <linux/fs.h>
  27 #include <linux/slab.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/pgtable.h>
  30 #include <asm/system.h>
  31 #include <asm/io.h>
  32 #include <asm/processor.h>
  33 #include <asm/mmu_context.h>
  34 #include <asm/fpu.h>
  35 #include <asm/reset-regs.h>
  36 #include <asm/gdb-stub.h>
  37 #include "internal.h"
  38
  39 /*
  40  * power management idle function, if any..
  41  */
  42 void (*pm_idle)(void);
  43 EXPORT_SYMBOL(pm_idle);
  44
  45 /*
  46  * return saved PC of a blocked thread.
  47  */
  48 unsigned long thread_saved_pc(struct task_struct *tsk)
  49 {
  50         return ((unsigned long *) tsk->thread.sp)[3];
  51 }
  52
  53 /*
  54  * power off function, if any
  55  */
  56 void (*pm_power_off)(void);
  57 EXPORT_SYMBOL(pm_power_off);
  58
  59 #if !defined(CONFIG_SMP) || defined(CONFIG_HOTPLUG_CPU)
  60 /*
  61  * we use this if we don't have any better idle routine
  62  */
  63 static void default_idle(void)
  64 {
  65         local_irq_disable();
  66         if (!need_resched())
  67                 safe_halt();
  68         else
  69                 local_irq_enable();
  70 }
  71
  72 #else /* !CONFIG_SMP || CONFIG_HOTPLUG_CPU  */
  73 /*
  74  * On SMP it's slightly faster (but much more power-consuming!)
  75  * to poll the ->work.need_resched flag instead of waiting for the
  76  * cross-CPU IPI to arrive. Use this option with caution.
  77  */
  78 static inline void poll_idle(void)
  79 {
  80         int oldval;
  81
  82         local_irq_enable();
  83
  84         /*
  85          * Deal with another CPU just having chosen a thread to
  86          * run here:
  87          */
  88         oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
  89
  90         if (!oldval) {
  91                 set_thread_flag(TIF_POLLING_NRFLAG);
  92                 while (!need_resched())
  93                         cpu_relax();
  94                 clear_thread_flag(TIF_POLLING_NRFLAG);
  95         } else {
  96                 set_need_resched();
  97         }
  98 }
  99 #endif /* !CONFIG_SMP || CONFIG_HOTPLUG_CPU */
 100
 101 /*
 102  * the idle thread
 103  * - there's no useful work to be done, so just try to conserve power and have
 104  *   a low exit latency (ie sit in a loop waiting for somebody to say that
 105  *   they'd like to reschedule)
 106  */
 107 void cpu_idle(void)
 108 {
 109         /* endless idle loop with no priority at all */
 110         for (;;) {
 111                 while (!need_resched()) {
 112                         void (*idle)(void);
 113
 114                         smp_rmb();
 115                         idle = pm_idle;
 116                         if (!idle) {
 117 #if defined(CONFIG_SMP) && !defined(CONFIG_HOTPLUG_CPU)
 118                                 idle = poll_idle;
 119 #else  /* CONFIG_SMP && !CONFIG_HOTPLUG_CPU */
 120                                 idle = default_idle;
 121 #endif /* CONFIG_SMP && !CONFIG_HOTPLUG_CPU */
 122                         }
 123                         idle();
 124                 }
 125
 126                 preempt_enable_no_resched();
 127                 schedule();
 128                 preempt_disable();
 129         }
 130 }
 131
 132 void release_segments(struct mm_struct *mm)
 133 {
 134 }
 135
 136 void machine_restart(char *cmd)
 137 {
 138 #ifdef CONFIG_GDBSTUB
 139         gdbstub_exit(0);
 140 #endif
 141
 142 #ifdef mn10300_unit_hard_reset
 143         mn10300_unit_hard_reset();
 144 #else
 145         mn10300_proc_hard_reset();
 146 #endif
 147 }
 148
 149 void machine_halt(void)
 150 {
 151 #ifdef CONFIG_GDBSTUB
 152         gdbstub_exit(0);
 153 #endif
 154 }
 155
 156 void machine_power_off(void)
 157 {
 158 #ifdef CONFIG_GDBSTUB
 159         gdbstub_exit(0);
 160 #endif
 161 }
 162
 163 void show_regs(struct pt_regs *regs)
 164 {
 165 }
 166
 167 /*
 168  * create a kernel thread
 169  */
 170 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 171 {
 172         struct pt_regs regs;
 173
 174         memset(&regs, 0, sizeof(regs));
 175
 176         regs.a2 = (unsigned long) fn;
 177         regs.d2 = (unsigned long) arg;
 178         regs.pc = (unsigned long) kernel_thread_helper;
 179         local_save_flags(regs.epsw);
 180         regs.epsw |= EPSW_IE | EPSW_IM_7;
 181
 182         /* Ok, create the new process.. */
 183         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0,
 184                        NULL, NULL);
 185 }
 186 EXPORT_SYMBOL(kernel_thread);
 187
 188 /*
 189  * free current thread data structures etc..
 190  */
 191 void exit_thread(void)
 192 {
 193         exit_fpu();
 194 }
 195
 196 void flush_thread(void)
 197 {
 198         flush_fpu();
 199 }
 200
 201 void release_thread(struct task_struct *dead_task)
 202 {
 203 }
 204
 205 /*
 206  * we do not have to muck with descriptors here, that is
 207  * done in switch_mm() as needed.
 208  */
 209 void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
 210 {
 211 }
 212
 213 /*
 214  * this gets called before we allocate a new thread and copy the current task
 215  * into it so that we can store lazy state into memory
 216  */
 217 void prepare_to_copy(struct task_struct *tsk)
 218 {
 219         unlazy_fpu(tsk);
 220 }
 221
 222 /*
 223  * set up the kernel stack for a new thread and copy arch-specific thread
 224  * control information
 225  */
 226 int copy_thread(unsigned long clone_flags,
 227                 unsigned long c_usp, unsigned long ustk_size,
 228                 struct task_struct *p, struct pt_regs *kregs)
 229 {
 230         struct thread_info *ti = task_thread_info(p);
 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 = current_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         ti->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 current_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 ?: current_frame()->sp,
 288                        current_frame(), 0, parent_tidptr, child_tidptr);
 289 }
 290
 291 asmlinkage long sys_fork(void)
 292 {
 293         return do_fork(SIGCHLD, current_frame()->sp,
 294                        current_frame(), 0, NULL, NULL);
 295 }
 296
 297 asmlinkage long sys_vfork(void)
 298 {
 299         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, current_frame()->sp,
 300                        current_frame(), 0, NULL, NULL);
 301 }
 302
 303 asmlinkage long sys_execve(const char __user *name,
 304                            const char __user *const __user *argv,
 305                            const char __user *const __user *envp)
 306 {
 307         char *filename;
 308         int error;
 309
 310         filename = getname(name);
 311         error = PTR_ERR(filename);
 312         if (IS_ERR(filename))
 313                 return error;
 314         error = do_execve(filename, argv, envp, current_frame());
 315         putname(filename);
 316         return error;
 317 }
 318
 319 unsigned long get_wchan(struct task_struct *p)
 320 {
 321         return p->thread.wchan;
 322 }