summaryrefslogtreecommitdiff
path: root/arch/openrisc/kernel/process.c
blob: 486e46dd58833e138a22bc587d329bfe0596b39f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * OpenRISC process.c
 *
 * Linux architectural port borrowing liberally from similar works of
 * others.  All original copyrights apply as per the original source
 * declaration.
 *
 * Modifications for the OpenRISC architecture:
 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
 *
 * This file handles the architecture-dependent parts of process handling...
 */

#define __KERNEL_SYSCALLS__
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/elfcore.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/init_task.h>
#include <linux/mqueue.h>
#include <linux/fs.h>
#include <linux/reboot.h>

#include <linux/uaccess.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/spr_defs.h>

#include <linux/smp.h>

/*
 * Pointer to Current thread info structure.
 *
 * Used at user space -> kernel transitions.
 */
struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };

void machine_restart(char *cmd)
{
	do_kernel_restart(cmd);

	/* Give a grace period for failure to restart of 1s */
	mdelay(1000);

	/* Whoops - the platform was unable to reboot. Tell the user! */
	pr_emerg("Reboot failed -- System halted\n");
	while (1);
}

/*
 * Similar to machine_power_off, but don't shut off power.  Add code
 * here to freeze the system for e.g. post-mortem debug purpose when
 * possible.  This halt has nothing to do with the idle halt.
 */
void machine_halt(void)
{
	printk(KERN_INFO "*** MACHINE HALT ***\n");
	__asm__("l.nop 1");
}

/* If or when software power-off is implemented, add code here.  */
void machine_power_off(void)
{
	printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
	__asm__("l.nop 1");
}

/*
 * Send the doze signal to the cpu if available.
 * Make sure, that all interrupts are enabled
 */
void arch_cpu_idle(void)
{
	raw_local_irq_enable();
	if (mfspr(SPR_UPR) & SPR_UPR_PMP)
		mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
}

void (*pm_power_off) (void) = machine_power_off;
EXPORT_SYMBOL(pm_power_off);

/*
 * When a process does an "exec", machine state like FPU and debug
 * registers need to be reset.  This is a hook function for that.
 * Currently we don't have any such state to reset, so this is empty.
 */
void flush_thread(void)
{
}

void show_regs(struct pt_regs *regs)
{
	extern void show_registers(struct pt_regs *regs);

	show_regs_print_info(KERN_DEFAULT);
	/* __PHX__ cleanup this mess */
	show_registers(regs);
}

void release_thread(struct task_struct *dead_task)
{
}

/*
 * Copy the thread-specific (arch specific) info from the current
 * process to the new one p
 */
extern asmlinkage void ret_from_fork(void);

/*
 * copy_thread
 * @clone_flags: flags
 * @usp: user stack pointer or fn for kernel thread
 * @arg: arg to fn for kernel thread; always NULL for userspace thread
 * @p: the newly created task
 * @tls: the Thread Local Storage pointer for the new process
 *
 * At the top of a newly initialized kernel stack are two stacked pt_reg
 * structures.  The first (topmost) is the userspace context of the thread.
 * The second is the kernelspace context of the thread.
 *
 * A kernel thread will not be returning to userspace, so the topmost pt_regs
 * struct can be uninitialized; it _does_ need to exist, though, because
 * a kernel thread can become a userspace thread by doing a kernel_execve, in
 * which case the topmost context will be initialized and used for 'returning'
 * to userspace.
 *
 * The second pt_reg struct needs to be initialized to 'return' to
 * ret_from_fork.  A kernel thread will need to set r20 to the address of
 * a function to call into (with arg in r22); userspace threads need to set
 * r20 to NULL in which case ret_from_fork will just continue a return to
 * userspace.
 *
 * A kernel thread 'fn' may return; this is effectively what happens when
 * kernel_execve is called.  In that case, the userspace pt_regs must have
 * been initialized (which kernel_execve takes care of, see start_thread
 * below); ret_from_fork will then continue its execution causing the
 * 'kernel thread' to return to userspace as a userspace thread.
 */

int
copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
	unsigned long clone_flags = args->flags;
	unsigned long usp = args->stack;
	unsigned long arg = args->stack_size;
	unsigned long tls = args->tls;
	struct pt_regs *userregs;
	struct pt_regs *kregs;
	unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
	unsigned long top_of_kernel_stack;

	top_of_kernel_stack = sp;

	/* Locate userspace context on stack... */
	sp -= STACK_FRAME_OVERHEAD;	/* redzone */
	sp -= sizeof(struct pt_regs);
	userregs = (struct pt_regs *) sp;

	/* ...and kernel context */
	sp -= STACK_FRAME_OVERHEAD;	/* redzone */
	sp -= sizeof(struct pt_regs);
	kregs = (struct pt_regs *)sp;

	if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
		memset(kregs, 0, sizeof(struct pt_regs));
		kregs->gpr[20] = usp; /* fn, kernel thread */
		kregs->gpr[22] = arg;
	} else {
		*userregs = *current_pt_regs();

		if (usp)
			userregs->sp = usp;

		/*
		 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer.
		 */
		if (clone_flags & CLONE_SETTLS)
			userregs->gpr[10] = tls;

		userregs->gpr[11] = 0;	/* Result from fork() */

		kregs->gpr[20] = 0;	/* Userspace thread */
	}

	/*
	 * _switch wants the kernel stack page in pt_regs->sp so that it
	 * can restore it to thread_info->ksp... see _switch for details.
	 */
	kregs->sp = top_of_kernel_stack;
	kregs->gpr[9] = (unsigned long)ret_from_fork;

	task_thread_info(p)->ksp = (unsigned long)kregs;

	return 0;
}

/*
 * Set up a thread for executing a new program
 */
void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
{
	unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;

	memset(regs, 0, sizeof(struct pt_regs));

	regs->pc = pc;
	regs->sr = sr;
	regs->sp = sp;
}

extern struct thread_info *_switch(struct thread_info *old_ti,
				   struct thread_info *new_ti);
extern int lwa_flag;

struct task_struct *__switch_to(struct task_struct *old,
				struct task_struct *new)
{
	struct task_struct *last;
	struct thread_info *new_ti, *old_ti;
	unsigned long flags;

	local_irq_save(flags);

	/* current_set is an array of saved current pointers
	 * (one for each cpu). we need them at user->kernel transition,
	 * while we save them at kernel->user transition
	 */
	new_ti = new->stack;
	old_ti = old->stack;

	lwa_flag = 0;

	current_thread_info_set[smp_processor_id()] = new_ti;
	last = (_switch(old_ti, new_ti))->task;

	local_irq_restore(flags);

	return last;
}

/*
 * Write out registers in core dump format, as defined by the
 * struct user_regs_struct
 */
void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
{
	dest[0] = 0; /* r0 */
	memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
	dest[32] = regs->pc;
	dest[33] = regs->sr;
	dest[34] = 0;
	dest[35] = 0;
}

unsigned long __get_wchan(struct task_struct *p)
{
	/* TODO */

	return 0;
}