arch/cris/kernel/process.c

   1 /* $Id: process.c,v 1.21 2005/03/04 08:16:17 starvik Exp $
   2  *
   3  *  linux/arch/cris/kernel/process.c
   4  *
   5  *  Copyright (C) 1995  Linus Torvalds
   6  *  Copyright (C) 2000-2002  Axis Communications AB
   7  *
   8  *  Authors:   Bjorn Wesen (bjornw@axis.com)
   9  *
  10  *  $Log: process.c,v $
  11  *  Revision 1.21  2005/03/04 08:16:17  starvik
  12  *  Merge of Linux 2.6.11.
  13  *
  14  *  Revision 1.20  2005/01/18 05:57:22  starvik
  15  *  Renamed hlt_counter to cris_hlt_counter and made it global.
  16  *
  17  *  Revision 1.19  2004/10/19 13:07:43  starvik
  18  *  Merge of Linux 2.6.9
  19  *
  20  *  Revision 1.18  2004/08/16 12:37:23  starvik
  21  *  Merge of Linux 2.6.8
  22  *
  23  *  Revision 1.17  2004/04/05 13:53:48  starvik
  24  *  Merge of Linux 2.6.5
  25  *
  26  *  Revision 1.16  2003/10/27 08:04:33  starvik
  27  *  Merge of Linux 2.6.0-test9
  28  *
  29  *  Revision 1.15  2003/09/11 07:29:52  starvik
  30  *  Merge of Linux 2.6.0-test5
  31  *
  32  *  Revision 1.14  2003/06/10 10:21:12  johana
  33  *  Moved thread_saved_pc() from arch/cris/kernel/process.c to
  34  *  subarch specific process.c. arch-v32 has an erp, no irp.
  35  *
  36  *  Revision 1.13  2003/04/09 05:20:47  starvik
  37  *  Merge of Linux 2.5.67
  38  *
  39  *  Revision 1.12  2002/12/11 15:41:11  starvik
  40  *  Extracted v10 (ETRAX 100LX) specific stuff to arch/cris/arch-v10/kernel
  41  *
  42  *  Revision 1.11  2002/12/10 09:00:10  starvik
  43  *  Merge of Linux 2.5.51
  44  *
  45  *  Revision 1.10  2002/11/27 08:42:34  starvik
  46  *  Argument to user_regs() is thread_info*
  47  *
  48  *  Revision 1.9  2002/11/26 09:44:21  starvik
  49  *  New threads exits through ret_from_fork (necessary for preemptive scheduling)
  50  *
  51  *  Revision 1.8  2002/11/19 14:35:24  starvik
  52  *  Changes from linux 2.4
  53  *  Changed struct initializer syntax to the currently prefered notation
  54  *
  55  *  Revision 1.7  2002/11/18 07:39:42  starvik
  56  *  thread_saved_pc moved here from processor.h
  57  *
  58  *  Revision 1.6  2002/11/14 06:51:27  starvik
  59  *  Made cpu_idle more similar with other archs
  60  *  init_task_union -> init_thread_union
  61  *  Updated for new interrupt macros
  62  *  sys_clone and do_fork have a new argument, user_tid
  63  *
  64  *  Revision 1.5  2002/11/05 06:45:11  starvik
  65  *  Merge of Linux 2.5.45
  66  *
  67  *  Revision 1.4  2002/02/05 15:37:44  bjornw
  68  *  Need init_task.h
  69  *
  70  *  Revision 1.3  2002/01/21 15:22:49  bjornw
  71  *  current->counter is gone
  72  *
  73  *  Revision 1.22  2001/11/13 09:40:43  orjanf
  74  *  Added dump_fpu (needed for core dumps).
  75  *
  76  *  Revision 1.21  2001/11/12 18:26:21  pkj
  77  *  Fixed compiler warnings.
  78  *
  79  *  Revision 1.20  2001/10/03 08:21:39  jonashg
  80  *  cause_of_death does not exist if CONFIG_SVINTO_SIM is defined.
  81  *
  82  *  Revision 1.19  2001/09/26 11:52:54  bjornw
  83  *  INIT_MMAP is gone in 2.4.10
  84  *
  85  *  Revision 1.18  2001/08/21 21:43:51  hp
  86  *  Move last watchdog fix inside #ifdef CONFIG_ETRAX_WATCHDOG
  87  *
  88  *  Revision 1.17  2001/08/21 13:48:01  jonashg
  89  *  Added fix by HP to avoid oops when doing a hard_reset_now.
  90  *
  91  *  Revision 1.16  2001/06/21 02:00:40  hp
  92  *      * entry.S: Include asm/unistd.h.
  93  *      (_sys_call_table): Use section .rodata, not .data.
  94  *      (_kernel_thread): Move from...
  95  *      * process.c: ... here.
  96  *      * entryoffsets.c (VAL): Break out from...
  97  *      (OF): Use VAL.
  98  *      (LCLONE_VM): New asmified value from CLONE_VM.
  99  *
 100  *  Revision 1.15  2001/06/20 16:31:57  hp
 101  *  Add comments to describe empty functions according to review.
 102  *
 103  *  Revision 1.14  2001/05/29 11:27:59  markusl
 104  *  Fixed so that hard_reset_now will do reset even if watchdog wasn't enabled
 105  *
 106  *  Revision 1.13  2001/03/20 19:44:06  bjornw
 107  *  Use the 7th syscall argument for regs instead of current_regs
 108  *
 109  */
 110
 111 /*
 112  * This file handles the architecture-dependent parts of process handling..
 113  */
 114
 115 #include <asm/atomic.h>
 116 #include <asm/pgtable.h>
 117 #include <asm/uaccess.h>
 118 #include <asm/irq.h>
 119 #include <asm/system.h>
 120 #include <linux/module.h>
 121 #include <linux/spinlock.h>
 122 #include <linux/fs_struct.h>
 123 #include <linux/init_task.h>
 124 #include <linux/sched.h>
 125 #include <linux/fs.h>
 126 #include <linux/user.h>
 127 #include <linux/elfcore.h>
 128 #include <linux/mqueue.h>
 129 #include <linux/reboot.h>
 130
 131 //#define DEBUG
 132
 133 /*
 134  * Initial task structure. Make this a per-architecture thing,
 135  * because different architectures tend to have different
 136  * alignment requirements and potentially different initial
 137  * setup.
 138  */
 139
 140 static struct fs_struct init_fs = INIT_FS;
 141 static struct files_struct init_files = INIT_FILES;
 142 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
 143 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
 144 struct mm_struct init_mm = INIT_MM(init_mm);
 145
 146 EXPORT_SYMBOL(init_mm);
 147
 148 /*
 149  * Initial thread structure.
 150  *
 151  * We need to make sure that this is 8192-byte aligned due to the
 152  * way process stacks are handled. This is done by having a special
 153  * "init_task" linker map entry..
 154  */
 155 union thread_union init_thread_union
 156         __attribute__((__section__(".data.init_task"))) =
 157                 { INIT_THREAD_INFO(init_task) };
 158
 159 /*
 160  * Initial task structure.
 161  *
 162  * All other task structs will be allocated on slabs in fork.c
 163  */
 164 struct task_struct init_task = INIT_TASK(init_task);
 165
 166 EXPORT_SYMBOL(init_task);
 167
 168 /*
 169  * The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
 170  * there would ever be a halt sequence (for power save when idle) with
 171  * some largish delay when halting or resuming *and* a driver that can't
 172  * afford that delay.  The hlt_counter would then be checked before
 173  * executing the halt sequence, and the driver marks the unhaltable
 174  * region by enable_hlt/disable_hlt.
 175  */
 176
 177 int cris_hlt_counter=0;
 178
 179 void disable_hlt(void)
 180 {
 181         cris_hlt_counter++;
 182 }
 183
 184 EXPORT_SYMBOL(disable_hlt);
 185
 186 void enable_hlt(void)
 187 {
 188         cris_hlt_counter--;
 189 }
 190
 191 EXPORT_SYMBOL(enable_hlt);
 192
 193 /*
 194  * The following aren't currently used.
 195  */
 196 void (*pm_idle)(void);
 197
 198 /*
 199  * The idle thread. There's no useful work to be
 200  * done, so just try to conserve power and have a
 201  * low exit latency (ie sit in a loop waiting for
 202  * somebody to say that they'd like to reschedule)
 203  */
 204 void cpu_idle (void)
 205 {
 206         /* endless idle loop with no priority at all */
 207         while (1) {
 208                 while (!need_resched()) {
 209                         void (*idle)(void);
 210                         /*
 211                          * Mark this as an RCU critical section so that
 212                          * synchronize_kernel() in the unload path waits
 213                          * for our completion.
 214                          */
 215                         idle = pm_idle;
 216                         if (!idle)
 217                                 idle = default_idle;
 218                         idle();
 219                 }
 220                 preempt_enable_no_resched();
 221                 schedule();
 222                 preempt_disable();
 223         }
 224 }
 225
 226 void hard_reset_now (void);
 227
 228 void machine_restart(char *cmd)
 229 {
 230         hard_reset_now();
 231 }
 232
 233 /*
 234  * Similar to machine_power_off, but don't shut off power.  Add code
 235  * here to freeze the system for e.g. post-mortem debug purpose when
 236  * possible.  This halt has nothing to do with the idle halt.
 237  */
 238
 239 void machine_halt(void)
 240 {
 241 }
 242
 243 /* If or when software power-off is implemented, add code here.  */
 244
 245 void machine_power_off(void)
 246 {
 247 }
 248
 249 /*
 250  * When a process does an "exec", machine state like FPU and debug
 251  * registers need to be reset.  This is a hook function for that.
 252  * Currently we don't have any such state to reset, so this is empty.
 253  */
 254
 255 void flush_thread(void)
 256 {
 257 }
 258
 259 /* Fill in the fpu structure for a core dump. */
 260 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
 261 {
 262         return 0;
 263 }