1/*
2 * OpenRISC process.c
3 *
4 * Linux architectural port borrowing liberally from similar works of
5 * others.  All original copyrights apply as per the original source
6 * declaration.
7 *
8 * Modifications for the OpenRISC architecture:
9 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
11 *
12 *      This program is free software; you can redistribute it and/or
13 *      modify it under the terms of the GNU General Public License
14 *      as published by the Free Software Foundation; either version
15 *      2 of the License, or (at your option) any later version.
16 *
17 * This file handles the architecture-dependent parts of process handling...
18 */
19
20#define __KERNEL_SYSCALLS__
21#include <stdarg.h>
22
23#include <linux/errno.h>
24#include <linux/sched.h>
25#include <linux/kernel.h>
26#include <linux/module.h>
27#include <linux/mm.h>
28#include <linux/stddef.h>
29#include <linux/unistd.h>
30#include <linux/ptrace.h>
31#include <linux/slab.h>
32#include <linux/elfcore.h>
33#include <linux/interrupt.h>
34#include <linux/delay.h>
35#include <linux/init_task.h>
36#include <linux/mqueue.h>
37#include <linux/fs.h>
38
39#include <asm/uaccess.h>
40#include <asm/pgtable.h>
41#include <asm/io.h>
42#include <asm/processor.h>
43#include <asm/spr_defs.h>
44
45#include <linux/smp.h>
46
47/*
48 * Pointer to Current thread info structure.
49 *
50 * Used at user space -> kernel transitions.
51 */
52struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
53
54void machine_restart(void)
55{
56	printk(KERN_INFO "*** MACHINE RESTART ***\n");
57	__asm__("l.nop 1");
58}
59
60/*
61 * Similar to machine_power_off, but don't shut off power.  Add code
62 * here to freeze the system for e.g. post-mortem debug purpose when
63 * possible.  This halt has nothing to do with the idle halt.
64 */
65void machine_halt(void)
66{
67	printk(KERN_INFO "*** MACHINE HALT ***\n");
68	__asm__("l.nop 1");
69}
70
71/* If or when software power-off is implemented, add code here.  */
72void machine_power_off(void)
73{
74	printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
75	__asm__("l.nop 1");
76}
77
78void (*pm_power_off) (void) = machine_power_off;
79
80/*
81 * When a process does an "exec", machine state like FPU and debug
82 * registers need to be reset.  This is a hook function for that.
83 * Currently we don't have any such state to reset, so this is empty.
84 */
85void flush_thread(void)
86{
87}
88
89void show_regs(struct pt_regs *regs)
90{
91	extern void show_registers(struct pt_regs *regs);
92
93	show_regs_print_info(KERN_DEFAULT);
94	/* __PHX__ cleanup this mess */
95	show_registers(regs);
96}
97
98unsigned long thread_saved_pc(struct task_struct *t)
99{
100	return (unsigned long)user_regs(t->stack)->pc;
101}
102
103void release_thread(struct task_struct *dead_task)
104{
105}
106
107/*
108 * Copy the thread-specific (arch specific) info from the current
109 * process to the new one p
110 */
111extern asmlinkage void ret_from_fork(void);
112
113/*
114 * copy_thread
115 * @clone_flags: flags
116 * @usp: user stack pointer or fn for kernel thread
117 * @arg: arg to fn for kernel thread; always NULL for userspace thread
118 * @p: the newly created task
119 * @regs: CPU context to copy for userspace thread; always NULL for kthread
120 *
121 * At the top of a newly initialized kernel stack are two stacked pt_reg
122 * structures.  The first (topmost) is the userspace context of the thread.
123 * The second is the kernelspace context of the thread.
124 *
125 * A kernel thread will not be returning to userspace, so the topmost pt_regs
126 * struct can be uninitialized; it _does_ need to exist, though, because
127 * a kernel thread can become a userspace thread by doing a kernel_execve, in
128 * which case the topmost context will be initialized and used for 'returning'
129 * to userspace.
130 *
131 * The second pt_reg struct needs to be initialized to 'return' to
132 * ret_from_fork.  A kernel thread will need to set r20 to the address of
133 * a function to call into (with arg in r22); userspace threads need to set
134 * r20 to NULL in which case ret_from_fork will just continue a return to
135 * userspace.
136 *
137 * A kernel thread 'fn' may return; this is effectively what happens when
138 * kernel_execve is called.  In that case, the userspace pt_regs must have
139 * been initialized (which kernel_execve takes care of, see start_thread
140 * below); ret_from_fork will then continue its execution causing the
141 * 'kernel thread' to return to userspace as a userspace thread.
142 */
143
144int
145copy_thread(unsigned long clone_flags, unsigned long usp,
146	    unsigned long arg, struct task_struct *p)
147{
148	struct pt_regs *userregs;
149	struct pt_regs *kregs;
150	unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
151	unsigned long top_of_kernel_stack;
152
153	top_of_kernel_stack = sp;
154
155	p->set_child_tid = p->clear_child_tid = NULL;
156
157	/* Locate userspace context on stack... */
158	sp -= STACK_FRAME_OVERHEAD;	/* redzone */
159	sp -= sizeof(struct pt_regs);
160	userregs = (struct pt_regs *) sp;
161
162	/* ...and kernel context */
163	sp -= STACK_FRAME_OVERHEAD;	/* redzone */
164	sp -= sizeof(struct pt_regs);
165	kregs = (struct pt_regs *)sp;
166
167	if (unlikely(p->flags & PF_KTHREAD)) {
168		memset(kregs, 0, sizeof(struct pt_regs));
169		kregs->gpr[20] = usp; /* fn, kernel thread */
170		kregs->gpr[22] = arg;
171	} else {
172		*userregs = *current_pt_regs();
173
174		if (usp)
175			userregs->sp = usp;
176		userregs->gpr[11] = 0;	/* Result from fork() */
177
178		kregs->gpr[20] = 0;	/* Userspace thread */
179	}
180
181	/*
182	 * _switch wants the kernel stack page in pt_regs->sp so that it
183	 * can restore it to thread_info->ksp... see _switch for details.
184	 */
185	kregs->sp = top_of_kernel_stack;
186	kregs->gpr[9] = (unsigned long)ret_from_fork;
187
188	task_thread_info(p)->ksp = (unsigned long)kregs;
189
190	return 0;
191}
192
193/*
194 * Set up a thread for executing a new program
195 */
196void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
197{
198	unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
199
200	memset(regs, 0, sizeof(struct pt_regs));
201
202	regs->pc = pc;
203	regs->sr = sr;
204	regs->sp = sp;
205}
206
207/* Fill in the fpu structure for a core dump.  */
208int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
209{
210	/* TODO */
211	return 0;
212}
213
214extern struct thread_info *_switch(struct thread_info *old_ti,
215				   struct thread_info *new_ti);
216
217struct task_struct *__switch_to(struct task_struct *old,
218				struct task_struct *new)
219{
220	struct task_struct *last;
221	struct thread_info *new_ti, *old_ti;
222	unsigned long flags;
223
224	local_irq_save(flags);
225
226	/* current_set is an array of saved current pointers
227	 * (one for each cpu). we need them at user->kernel transition,
228	 * while we save them at kernel->user transition
229	 */
230	new_ti = new->stack;
231	old_ti = old->stack;
232
233	current_thread_info_set[smp_processor_id()] = new_ti;
234	last = (_switch(old_ti, new_ti))->task;
235
236	local_irq_restore(flags);
237
238	return last;
239}
240
241/*
242 * Write out registers in core dump format, as defined by the
243 * struct user_regs_struct
244 */
245void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
246{
247	dest[0] = 0; /* r0 */
248	memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
249	dest[32] = regs->pc;
250	dest[33] = regs->sr;
251	dest[34] = 0;
252	dest[35] = 0;
253}
254
255unsigned long get_wchan(struct task_struct *p)
256{
257	/* TODO */
258
259	return 0;
260}
261