1/* $Id: process.c,v 1.1.1.1 2007/08/03 18:51:42 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 1.1.1.1  2007/08/03 18:51:42  rnuti
12 *  Importing Linux MIPS Kernel 2.6.22
13 *
14 *  Revision 1.21  2005/03/04 08:16:17  starvik
15 *  Merge of Linux 2.6.11.
16 *
17 *  Revision 1.20  2005/01/18 05:57:22  starvik
18 *  Renamed hlt_counter to cris_hlt_counter and made it global.
19 *
20 *  Revision 1.19  2004/10/19 13:07:43  starvik
21 *  Merge of Linux 2.6.9
22 *
23 *  Revision 1.18  2004/08/16 12:37:23  starvik
24 *  Merge of Linux 2.6.8
25 *
26 *  Revision 1.17  2004/04/05 13:53:48  starvik
27 *  Merge of Linux 2.6.5
28 *
29 *  Revision 1.16  2003/10/27 08:04:33  starvik
30 *  Merge of Linux 2.6.0-test9
31 *
32 *  Revision 1.15  2003/09/11 07:29:52  starvik
33 *  Merge of Linux 2.6.0-test5
34 *
35 *  Revision 1.14  2003/06/10 10:21:12  johana
36 *  Moved thread_saved_pc() from arch/cris/kernel/process.c to
37 *  subarch specific process.c. arch-v32 has an erp, no irp.
38 *
39 *  Revision 1.13  2003/04/09 05:20:47  starvik
40 *  Merge of Linux 2.5.67
41 *
42 *  Revision 1.12  2002/12/11 15:41:11  starvik
43 *  Extracted v10 (ETRAX 100LX) specific stuff to arch/cris/arch-v10/kernel
44 *
45 *  Revision 1.11  2002/12/10 09:00:10  starvik
46 *  Merge of Linux 2.5.51
47 *
48 *  Revision 1.10  2002/11/27 08:42:34  starvik
49 *  Argument to user_regs() is thread_info*
50 *
51 *  Revision 1.9  2002/11/26 09:44:21  starvik
52 *  New threads exits through ret_from_fork (necessary for preemptive scheduling)
53 *
54 *  Revision 1.8  2002/11/19 14:35:24  starvik
55 *  Changes from linux 2.4
56 *  Changed struct initializer syntax to the currently prefered notation
57 *
58 *  Revision 1.7  2002/11/18 07:39:42  starvik
59 *  thread_saved_pc moved here from processor.h
60 *
61 *  Revision 1.6  2002/11/14 06:51:27  starvik
62 *  Made cpu_idle more similar with other archs
63 *  init_task_union -> init_thread_union
64 *  Updated for new interrupt macros
65 *  sys_clone and do_fork have a new argument, user_tid
66 *
67 *  Revision 1.5  2002/11/05 06:45:11  starvik
68 *  Merge of Linux 2.5.45
69 *
70 *  Revision 1.4  2002/02/05 15:37:44  bjornw
71 *  Need init_task.h
72 *
73 *  Revision 1.3  2002/01/21 15:22:49  bjornw
74 *  current->counter is gone
75 *
76 *  Revision 1.22  2001/11/13 09:40:43  orjanf
77 *  Added dump_fpu (needed for core dumps).
78 *
79 *  Revision 1.21  2001/11/12 18:26:21  pkj
80 *  Fixed compiler warnings.
81 *
82 *  Revision 1.20  2001/10/03 08:21:39  jonashg
83 *  cause_of_death does not exist if CONFIG_SVINTO_SIM is defined.
84 *
85 *  Revision 1.19  2001/09/26 11:52:54  bjornw
86 *  INIT_MMAP is gone in 2.4.10
87 *
88 *  Revision 1.18  2001/08/21 21:43:51  hp
89 *  Move last watchdog fix inside #ifdef CONFIG_ETRAX_WATCHDOG
90 *
91 *  Revision 1.17  2001/08/21 13:48:01  jonashg
92 *  Added fix by HP to avoid oops when doing a hard_reset_now.
93 *
94 *  Revision 1.16  2001/06/21 02:00:40  hp
95 *  	* entry.S: Include asm/unistd.h.
96 *  	(_sys_call_table): Use section .rodata, not .data.
97 *  	(_kernel_thread): Move from...
98 *  	* process.c: ... here.
99 *  	* entryoffsets.c (VAL): Break out from...
100 *  	(OF): Use VAL.
101 *  	(LCLONE_VM): New asmified value from CLONE_VM.
102 *
103 *  Revision 1.15  2001/06/20 16:31:57  hp
104 *  Add comments to describe empty functions according to review.
105 *
106 *  Revision 1.14  2001/05/29 11:27:59  markusl
107 *  Fixed so that hard_reset_now will do reset even if watchdog wasn't enabled
108 *
109 *  Revision 1.13  2001/03/20 19:44:06  bjornw
110 *  Use the 7th syscall argument for regs instead of current_regs
111 *
112 */
113
114/*
115 * This file handles the architecture-dependent parts of process handling..
116 */
117
118#include <asm/atomic.h>
119#include <asm/pgtable.h>
120#include <asm/uaccess.h>
121#include <asm/irq.h>
122#include <asm/system.h>
123#include <linux/module.h>
124#include <linux/spinlock.h>
125#include <linux/fs_struct.h>
126#include <linux/init_task.h>
127#include <linux/sched.h>
128#include <linux/fs.h>
129#include <linux/user.h>
130#include <linux/elfcore.h>
131#include <linux/mqueue.h>
132#include <linux/reboot.h>
133
134//#define DEBUG
135
136/*
137 * Initial task structure. Make this a per-architecture thing,
138 * because different architectures tend to have different
139 * alignment requirements and potentially different initial
140 * setup.
141 */
142
143static struct fs_struct init_fs = INIT_FS;
144static struct files_struct init_files = INIT_FILES;
145static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
146static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
147struct mm_struct init_mm = INIT_MM(init_mm);
148
149EXPORT_SYMBOL(init_mm);
150
151/*
152 * Initial thread structure.
153 *
154 * We need to make sure that this is 8192-byte aligned due to the
155 * way process stacks are handled. This is done by having a special
156 * "init_task" linker map entry..
157 */
158union thread_union init_thread_union
159	__attribute__((__section__(".data.init_task"))) =
160		{ INIT_THREAD_INFO(init_task) };
161
162/*
163 * Initial task structure.
164 *
165 * All other task structs will be allocated on slabs in fork.c
166 */
167struct task_struct init_task = INIT_TASK(init_task);
168
169EXPORT_SYMBOL(init_task);
170
171/*
172 * The hlt_counter, disable_hlt and enable_hlt is just here as a hook if
173 * there would ever be a halt sequence (for power save when idle) with
174 * some largish delay when halting or resuming *and* a driver that can't
175 * afford that delay.  The hlt_counter would then be checked before
176 * executing the halt sequence, and the driver marks the unhaltable
177 * region by enable_hlt/disable_hlt.
178 */
179
180int cris_hlt_counter=0;
181
182void disable_hlt(void)
183{
184	cris_hlt_counter++;
185}
186
187EXPORT_SYMBOL(disable_hlt);
188
189void enable_hlt(void)
190{
191	cris_hlt_counter--;
192}
193
194EXPORT_SYMBOL(enable_hlt);
195
196/*
197 * The following aren't currently used.
198 */
199void (*pm_idle)(void);
200
201/*
202 * The idle thread. There's no useful work to be
203 * done, so just try to conserve power and have a
204 * low exit latency (ie sit in a loop waiting for
205 * somebody to say that they'd like to reschedule)
206 */
207void cpu_idle (void)
208{
209	/* endless idle loop with no priority at all */
210	while (1) {
211		while (!need_resched()) {
212			void (*idle)(void);
213			/*
214			 * Mark this as an RCU critical section so that
215			 * synchronize_kernel() in the unload path waits
216			 * for our completion.
217			 */
218			idle = pm_idle;
219			if (!idle)
220				idle = default_idle;
221			idle();
222		}
223		preempt_enable_no_resched();
224		schedule();
225		preempt_disable();
226	}
227}
228
229void hard_reset_now (void);
230
231void machine_restart(char *cmd)
232{
233	hard_reset_now();
234}
235
236/*
237 * Similar to machine_power_off, but don't shut off power.  Add code
238 * here to freeze the system for e.g. post-mortem debug purpose when
239 * possible.  This halt has nothing to do with the idle halt.
240 */
241
242void machine_halt(void)
243{
244}
245
246/* If or when software power-off is implemented, add code here.  */
247
248void machine_power_off(void)
249{
250}
251
252/*
253 * When a process does an "exec", machine state like FPU and debug
254 * registers need to be reset.  This is a hook function for that.
255 * Currently we don't have any such state to reset, so this is empty.
256 */
257
258void flush_thread(void)
259{
260}
261
262/* Fill in the fpu structure for a core dump. */
263int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
264{
265        return 0;
266}
267