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                 schedule_preempt_disabled();
 127         }
 128 }
 129
 130 void release_segments(struct mm_struct *mm)
 131 {
 132 }
 133
 134 void machine_restart(char *cmd)
 135 {
 136 #ifdef CONFIG_KERNEL_DEBUGGER
 137         gdbstub_exit(0);
 138 #endif
 139
 140 #ifdef mn10300_unit_hard_reset
 141         mn10300_unit_hard_reset();
 142 #else
 143         mn10300_proc_hard_reset();
 144 #endif
 145 }
 146
 147 void machine_halt(void)
 148 {
 149 #ifdef CONFIG_KERNEL_DEBUGGER
 150         gdbstub_exit(0);
 151 #endif
 152 }
 153
 154 void machine_power_off(void)
 155 {
 156 #ifdef CONFIG_KERNEL_DEBUGGER
 157         gdbstub_exit(0);
 158 #endif
 159 }
 160
 161 void show_regs(struct pt_regs *regs)
 162 {
 163 }
 164
 165 /*
 166  * create a kernel thread
 167  */
 168 int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 169 {
 170         struct pt_regs regs;
 171
 172         memset(&regs, 0, sizeof(regs));
 173
 174         regs.a2 = (unsigned long) fn;
 175         regs.d2 = (unsigned long) arg;
 176         regs.pc = (unsigned long) kernel_thread_helper;
 177         local_save_flags(regs.epsw);
 178         regs.epsw |= EPSW_IE | EPSW_IM_7;
 179
 180         /* Ok, create the new process.. */
 181         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0,
 182                        NULL, NULL);
 183 }
 184 EXPORT_SYMBOL(kernel_thread);
 185
 186 /*
 187  * free current thread data structures etc..
 188  */
 189 void exit_thread(void)
 190 {
 191         exit_fpu();
 192 }
 193
 194 void flush_thread(void)
 195 {
 196         flush_fpu();
 197 }
 198
 199 void release_thread(struct task_struct *dead_task)
 200 {
 201 }
 202
 203 /*
 204  * we do not have to muck with descriptors here, that is
 205  * done in switch_mm() as needed.
 206  */
 207 void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
 208 {
 209 }
 210
 211 /*
 212  * this gets called before we allocate a new thread and copy the current task
 213  * into it so that we can store lazy state into memory
 214  */
 215 void prepare_to_copy(struct task_struct *tsk)
 216 {
 217         unlazy_fpu(tsk);
 218 }
 219
 220 /*
 221  * set up the kernel stack for a new thread and copy arch-specific thread
 222  * control information
 223  */
 224 int copy_thread(unsigned long clone_flags,
 225                 unsigned long c_usp, unsigned long ustk_size,
 226                 struct task_struct *p, struct pt_regs *kregs)
 227 {
 228         struct thread_info *ti = task_thread_info(p);
 229         struct pt_regs *c_uregs, *c_kregs, *uregs;
 230         unsigned long c_ksp;
 231
 232         uregs = current->thread.uregs;
 233
 234         c_ksp = (unsigned long) task_stack_page(p) + THREAD_SIZE;
 235
 236         /* allocate the userspace exception frame and set it up */
 237         c_ksp -= sizeof(struct pt_regs);
 238         c_uregs = (struct pt_regs *) c_ksp;
 239
 240         p->thread.uregs = c_uregs;
 241         *c_uregs = *uregs;
 242         c_uregs->sp = c_usp;
 243         c_uregs->epsw &= ~EPSW_FE; /* my FPU */
 244
 245         c_ksp -= 12; /* allocate function call ABI slack */
 246
 247         /* the new TLS pointer is passed in as arg #5 to sys_clone() */
 248         if (clone_flags & CLONE_SETTLS)
 249                 c_uregs->e2 = current_frame()->d3;
 250
 251         /* set up the return kernel frame if called from kernel_thread() */
 252         c_kregs = c_uregs;
 253         if (kregs != uregs) {
 254                 c_ksp -= sizeof(struct pt_regs);
 255                 c_kregs = (struct pt_regs *) c_ksp;
 256                 *c_kregs = *kregs;
 257                 c_kregs->sp = c_usp;
 258                 c_kregs->next = c_uregs;
 259 #ifdef CONFIG_MN10300_CURRENT_IN_E2
 260                 c_kregs->e2 = (unsigned long) p; /* current */
 261 #endif
 262
 263                 c_ksp -= 12; /* allocate function call ABI slack */
 264         }
 265
 266         /* set up things up so the scheduler can start the new task */
 267         ti->frame       = c_kregs;
 268         p->thread.a3    = (unsigned long) c_kregs;
 269         p->thread.sp    = c_ksp;
 270         p->thread.pc    = (unsigned long) ret_from_fork;
 271         p->thread.wchan = (unsigned long) ret_from_fork;
 272         p->thread.usp   = c_usp;
 273
 274         return 0;
 275 }
 276
 277 /*
 278  * clone a process
 279  * - tlsptr is retrieved by copy_thread() from current_frame()->d3
 280  */
 281 asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp,
 282                           int __user *parent_tidptr, int __user *child_tidptr,
 283                           int __user *tlsptr)
 284 {
 285         return do_fork(clone_flags, newsp ?: current_frame()->sp,
 286                        current_frame(), 0, parent_tidptr, child_tidptr);
 287 }
 288
 289 asmlinkage long sys_fork(void)
 290 {
 291         return do_fork(SIGCHLD, current_frame()->sp,
 292                        current_frame(), 0, NULL, NULL);
 293 }
 294
 295 asmlinkage long sys_vfork(void)
 296 {
 297         return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, current_frame()->sp,
 298                        current_frame(), 0, NULL, NULL);
 299 }
 300
 301 asmlinkage long sys_execve(const char __user *name,
 302                            const char __user *const __user *argv,
 303                            const char __user *const __user *envp)
 304 {
 305         char *filename;
 306         int error;
 307
 308         filename = getname(name);
 309         error = PTR_ERR(filename);
 310         if (IS_ERR(filename))
 311                 return error;
 312         error = do_execve(filename, argv, envp, current_frame());
 313         putname(filename);
 314         return error;
 315 }
 316
 317 unsigned long get_wchan(struct task_struct *p)
 318 {
 319         return p->thread.wchan;
 320 }