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/slab.h>
  22 #include <linux/user.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/delay.h>
  25 #include <linux/reboot.h>
  26 #include <linux/percpu.h>
  27 #include <linux/err.h>
  28 #include <linux/fs.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 /*
  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 /*
  73  * the idle thread
  74  * - there's no useful work to be done, so just try to conserve power and have
  75  *   a low exit latency (ie sit in a loop waiting for somebody to say that
  76  *   they'd like to reschedule)
  77  */
  78 void cpu_idle(void)
  79 {
  80         int cpu = smp_processor_id();
  81
  82         /* endless idle loop with no priority at all */
  83         for (;;) {
  84                 while (!need_resched()) {
  85                         void (*idle)(void);
  86
  87                         smp_rmb();
  88                         idle = pm_idle;
  89                         if (!idle)
  90                                 idle = default_idle;
  91
  92                         irq_stat[cpu].idle_timestamp = jiffies;
  93                         idle();
  94                 }
  95
  96                 preempt_enable_no_resched();
  97                 schedule();
  98                 preempt_disable();
  99         }
 100 }
 101
 102 void release_segments(struct mm_struct *mm)
 103 {
 104 }
 105
 106 void machine_restart(char *cmd)
 107 {
 108 #ifdef CONFIG_GDBSTUB
 109         gdbstub_exit(0);
 110 #endif
 111
 112 #ifdef mn10300_unit_hard_reset
 113         mn10300_unit_hard_reset();
 114 #else
 115         mn10300_proc_hard_reset();
 116 #endif
 117 }
 118
 119 void machine_halt(void)
 120 {
 121 #ifdef CONFIG_GDBSTUB
 122         gdbstub_exit(0);
 123 #endif
 124 }
 125
 126 void machine_power_off(void)
 127 {
 128 #ifdef CONFIG_GDBSTUB
 129         gdbstub_exit(0);
 130 #endif
 131 }
 132
 133 void show_regs(struct pt_regs *regs)
 134 {
 135 }
 136
 137 /*
 138  * create a kernel thread
 139  */
 140 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 141 {
 142         struct pt_regs regs;
 143
 144         memset(&regs, 0, sizeof(regs));
 145
 146         regs.a2 = (unsigned long) fn;
 147         regs.d2 = (unsigned long) arg;
 148         regs.pc = (unsigned long) kernel_thread_helper;
 149         local_save_flags(regs.epsw);
 150         regs.epsw |= EPSW_IE | EPSW_IM_7;
 151
 152         /* Ok, create the new process.. */
 153         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0,
 154                        NULL, NULL);
 155 }
 156
 157 /*
 158  * free current thread data structures etc..
 159  */
 160 void exit_thread(void)
 161 {
 162         exit_fpu();
 163 }
 164
 165 void flush_thread(void)
 166 {
 167         flush_fpu();
 168 }
 169
 170 void release_thread(struct task_struct *dead_task)
 171 {
 172 }
 173
 174 /*
 175  * we do not have to muck with descriptors here, that is
 176  * done in switch_mm() as needed.
 177  */
 178 void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
 179 {
 180 }
 181
 182 /*
 183  * this gets called before we allocate a new thread and copy the current task
 184  * into it so that we can store lazy state into memory
 185  */
 186 void prepare_to_copy(struct task_struct *tsk)
 187 {
 188         unlazy_fpu(tsk);
 189 }
 190
 191 /*
 192  * set up the kernel stack for a new thread and copy arch-specific thread
 193  * control information
 194  */
 195 int copy_thread(int nr, unsigned long clone_flags,
 196                 unsigned long c_usp, unsigned long ustk_size,
 197                 struct task_struct *p, struct pt_regs *kregs)
 198 {
 199         struct pt_regs *c_uregs, *c_kregs, *uregs;
 200         unsigned long c_ksp;
 201
 202         uregs = current->thread.uregs;
 203
 204         c_ksp = (unsigned long) task_stack_page(p) + THREAD_SIZE;
 205
 206         /* allocate the userspace exception frame and set it up */
 207         c_ksp -= sizeof(struct pt_regs);
 208         c_uregs = (struct pt_regs *) c_ksp;
 209
 210         p->thread.uregs = c_uregs;
 211         *c_uregs = *uregs;
 212         c_uregs->sp = c_usp;
 213         c_uregs->epsw &= ~EPSW_FE; /* my FPU */
 214
 215         c_ksp -= 12; /* allocate function call ABI slack */
 216
 217         /* the new TLS pointer is passed in as arg #5 to sys_clone() */
 218         if (clone_flags & CLONE_SETTLS)
 219                 c_uregs->e2 = __frame->d3;
 220
 221         /* set up the return kernel frame if called from kernel_thread() */
 222         c_kregs = c_uregs;
 223         if (kregs != uregs) {
 224                 c_ksp -= sizeof(struct pt_regs);
 225                 c_kregs = (struct pt_regs *) c_ksp;
 226                 *c_kregs = *kregs;
 227                 c_kregs->sp = c_usp;
 228                 c_kregs->next = c_uregs;
 229 #ifdef CONFIG_MN10300_CURRENT_IN_E2
 230                 c_kregs->e2 = (unsigned long) p; /* current */
 231 #endif
 232
 233                 c_ksp -= 12; /* allocate function call ABI slack */
 234         }
 235
 236         /* set up things up so the scheduler can start the new task */
 237         p->thread.__frame = c_kregs;
 238         p->thread.a3    = (unsigned long) c_kregs;
 239         p->thread.sp    = c_ksp;
 240         p->thread.pc    = (unsigned long) ret_from_fork;
 241         p->thread.wchan = (unsigned long) ret_from_fork;
 242         p->thread.usp   = c_usp;
 243
 244         return 0;
 245 }
 246
 247 /*
 248  * clone a process
 249  * - tlsptr is retrieved by copy_thread() from __frame->d3
 250  */
 251 asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp,
 252                           int __user *parent_tidptr, int __user *child_tidptr,
 253                           int __user *tlsptr)
 254 {
 255         return do_fork(clone_flags, newsp ?: __frame->sp, __frame, 0,
 256                        parent_tidptr, child_tidptr);
 257 }
 258
 259 asmlinkage long sys_fork(void)
 260 {
 261         return do_fork(SIGCHLD, __frame->sp, __frame, 0, NULL, NULL);
 262 }
 263
 264 asmlinkage long sys_vfork(void)
 265 {
 266         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, __frame->sp, __frame,
 267                        0, NULL, NULL);
 268 }
 269
 270 asmlinkage long sys_execve(char __user *name,
 271                            char __user * __user *argv,
 272                            char __user * __user *envp)
 273 {
 274         char *filename;
 275         int error;
 276
 277         lock_kernel();
 278
 279         filename = getname(name);
 280         error = PTR_ERR(filename);
 281         if (!IS_ERR(filename)) {
 282                 error = do_execve(filename, argv, envp, __frame);
 283                 if (error == 0)
 284                         current->ptrace &= ~PT_DTRACE;
 285
 286                 putname(filename);
 287         }
 288
 289         unlock_kernel();
 290         return error;
 291 }
 292
 293 unsigned long get_wchan(struct task_struct *p)
 294 {
 295         return p->thread.wchan;
 296 }