/*
* 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 program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* This file handles the architecture-dependent parts of process handling...
*/
#define __KERNEL_SYSCALLS__
#include <stdarg.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/module.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 <asm/uaccess.h>
#include <asm/pgtable.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(void)
{
printk(KERN_INFO "*** MACHINE RESTART ***\n");
__asm__("l.nop 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");
}
void (*pm_power_off) (void) = machine_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);
}
unsigned long thread_saved_pc(struct task_struct *t)
{
return (unsigned long)user_regs(t->stack)->pc;
}
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
* @regs: CPU context to copy for userspace thread; always NULL for kthread
*
* 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(unsigned long clone_flags, unsigned long usp,
unsigned long arg, struct task_struct *p)
{
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;
p->set_child_tid = p->clear_child_tid = NULL;
/* 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)) {
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;
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;
set_fs(USER_DS);
memset(regs, 0, sizeof(struct pt_regs));
regs->pc = pc;
regs->sr = sr;
regs->sp = sp;
}
/* Fill in the fpu structure for a core dump. */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
{
/* TODO */
return 0;
}
extern struct thread_info *_switch(struct thread_info *old_ti,
struct thread_info *new_ti);
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;
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;
}
