Linux 4.8-rc8
[linux/fpc-iii.git] / arch / openrisc / kernel / process.c
blob7095dfe7666ba3dd55a0807ffd7d09b00af3ccc2
1 /*
2 * OpenRISC process.c
4 * Linux architectural port borrowing liberally from similar works of
5 * others. All original copyrights apply as per the original source
6 * declaration.
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>
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.
17 * This file handles the architecture-dependent parts of process handling...
20 #define __KERNEL_SYSCALLS__
21 #include <stdarg.h>
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>
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>
45 #include <linux/smp.h>
48 * Pointer to Current thread info structure.
50 * Used at user space -> kernel transitions.
52 struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
54 void machine_restart(void)
56 printk(KERN_INFO "*** MACHINE RESTART ***\n");
57 __asm__("l.nop 1");
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.
65 void machine_halt(void)
67 printk(KERN_INFO "*** MACHINE HALT ***\n");
68 __asm__("l.nop 1");
71 /* If or when software power-off is implemented, add code here. */
72 void machine_power_off(void)
74 printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
75 __asm__("l.nop 1");
78 void (*pm_power_off) (void) = machine_power_off;
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.
85 void flush_thread(void)
89 void show_regs(struct pt_regs *regs)
91 extern void show_registers(struct pt_regs *regs);
93 show_regs_print_info(KERN_DEFAULT);
94 /* __PHX__ cleanup this mess */
95 show_registers(regs);
98 unsigned long thread_saved_pc(struct task_struct *t)
100 return (unsigned long)user_regs(t->stack)->pc;
103 void release_thread(struct task_struct *dead_task)
108 * Copy the thread-specific (arch specific) info from the current
109 * process to the new one p
111 extern asmlinkage void ret_from_fork(void);
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
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.
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.
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.
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.
145 copy_thread(unsigned long clone_flags, unsigned long usp,
146 unsigned long arg, struct task_struct *p)
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;
153 top_of_kernel_stack = sp;
155 p->set_child_tid = p->clear_child_tid = NULL;
157 /* Locate userspace context on stack... */
158 sp -= STACK_FRAME_OVERHEAD; /* redzone */
159 sp -= sizeof(struct pt_regs);
160 userregs = (struct pt_regs *) sp;
162 /* ...and kernel context */
163 sp -= STACK_FRAME_OVERHEAD; /* redzone */
164 sp -= sizeof(struct pt_regs);
165 kregs = (struct pt_regs *)sp;
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();
174 if (usp)
175 userregs->sp = usp;
176 userregs->gpr[11] = 0; /* Result from fork() */
178 kregs->gpr[20] = 0; /* Userspace thread */
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.
185 kregs->sp = top_of_kernel_stack;
186 kregs->gpr[9] = (unsigned long)ret_from_fork;
188 task_thread_info(p)->ksp = (unsigned long)kregs;
190 return 0;
194 * Set up a thread for executing a new program
196 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
198 unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
200 memset(regs, 0, sizeof(struct pt_regs));
202 regs->pc = pc;
203 regs->sr = sr;
204 regs->sp = sp;
207 /* Fill in the fpu structure for a core dump. */
208 int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
210 /* TODO */
211 return 0;
214 extern struct thread_info *_switch(struct thread_info *old_ti,
215 struct thread_info *new_ti);
217 struct task_struct *__switch_to(struct task_struct *old,
218 struct task_struct *new)
220 struct task_struct *last;
221 struct thread_info *new_ti, *old_ti;
222 unsigned long flags;
224 local_irq_save(flags);
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
230 new_ti = new->stack;
231 old_ti = old->stack;
233 current_thread_info_set[smp_processor_id()] = new_ti;
234 last = (_switch(old_ti, new_ti))->task;
236 local_irq_restore(flags);
238 return last;
242 * Write out registers in core dump format, as defined by the
243 * struct user_regs_struct
245 void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
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;
255 unsigned long get_wchan(struct task_struct *p)
257 /* TODO */
259 return 0;