OpenRISC: Scheduling/Process management

/*

 * OpenRISC Linux

 *

 * Linux architectural port borrowing liberally from similar works of

 * others.  All original copyrights apply as per the original source

 * declaration.

 *

 * OpenRISC implementation:

 * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>

 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>

 * et al.

 *

 * 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.

 */

#ifndef _ASM_THREAD_INFO_H

#define _ASM_THREAD_INFO_H

#ifdef __KERNEL__

#ifndef __ASSEMBLY__

#include <asm/types.h>

#include <asm/processor.h>

#endif

/* THREAD_SIZE is the size of the task_struct/kernel_stack combo.

 * normally, the stack is found by doing something like p + THREAD_SIZE

 * in or32, a page is 8192 bytes, which seems like a sane size

 */

#define THREAD_SIZE_ORDER 0

#define THREAD_SIZE       (PAGE_SIZE << THREAD_SIZE_ORDER)

/*

 * low level task data that entry.S needs immediate access to

 * - this struct should fit entirely inside of one cache line

 * - this struct shares the supervisor stack pages

 * - if the contents of this structure are changed, the assembly constants

 *   must also be changed

 */

#ifndef __ASSEMBLY__

typedef unsigned long mm_segment_t;

struct thread_info {

	struct task_struct	*task;		/* main task structure */

	struct exec_domain	*exec_domain;	/* execution domain */

	unsigned long		flags;		/* low level flags */

	__u32			cpu;		/* current CPU */

	__s32			preempt_count; /* 0 => preemptable, <0 => BUG */

	mm_segment_t		addr_limit; /* thread address space:

					       0-0x7FFFFFFF for user-thead

					       0-0xFFFFFFFF for kernel-thread

					     */

	struct restart_block    restart_block;

	__u8			supervisor_stack[0];

	/* saved context data */

	unsigned long           ksp;

};

#endif

/*

 * macros/functions for gaining access to the thread information structure

 *

 * preempt_count needs to be 1 initially, until the scheduler is functional.

 */

#ifndef __ASSEMBLY__

#define INIT_THREAD_INFO(tsk)				\

{							\

	.task		= &tsk,				\

	.exec_domain	= &default_exec_domain,		\

	.flags		= 0,				\

	.cpu		= 0,				\

	.preempt_count	= 1,				\

	.addr_limit	= KERNEL_DS,			\

	.restart_block  = {				\

			  .fn = do_no_restart_syscall,	\

	},						\

	.ksp            = 0,                            \

}

#define init_thread_info	(init_thread_union.thread_info)

/* how to get the thread information struct from C */

register struct thread_info *current_thread_info_reg asm("r10");

#define current_thread_info()   (current_thread_info_reg)

#define get_thread_info(ti) get_task_struct((ti)->task)

#define put_thread_info(ti) put_task_struct((ti)->task)

#endif /* !__ASSEMBLY__ */

/*

 * thread information flags

 *   these are process state flags that various assembly files may need to

 *   access

 *   - pending work-to-be-done flags are in LSW

 *   - other flags in MSW

 */

#define TIF_SYSCALL_TRACE	0	/* syscall trace active */

#define TIF_NOTIFY_RESUME	1	/* resumption notification requested */

#define TIF_SIGPENDING		2	/* signal pending */

#define TIF_NEED_RESCHED	3	/* rescheduling necessary */

#define TIF_SINGLESTEP		4	/* restore singlestep on return to user

					 * mode

					 */

#define TIF_SYSCALL_TRACEPOINT  8       /* for ftrace syscall instrumentation */

#define TIF_RESTORE_SIGMASK     9

#define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling						 * TIF_NEED_RESCHED

					 */

#define TIF_MEMDIE              17

#define _TIF_SYSCALL_TRACE	(1<<TIF_SYSCALL_TRACE)

#define _TIF_NOTIFY_RESUME	(1<<TIF_NOTIFY_RESUME)

#define _TIF_SIGPENDING		(1<<TIF_SIGPENDING)

#define _TIF_NEED_RESCHED	(1<<TIF_NEED_RESCHED)

#define _TIF_SINGLESTEP		(1<<TIF_SINGLESTEP)

#define _TIF_RESTORE_SIGMASK     (1<<TIF_RESTORE_SIGMASK)

#define _TIF_POLLING_NRFLAG	(1<<TIF_POLLING_NRFLAG)

/* Work to do when returning from interrupt/exception */

/* For OpenRISC, this is anything in the LSW other than syscall trace */

#define _TIF_WORK_MASK (0xff & ~(_TIF_SYSCALL_TRACE|_TIF_SINGLESTEP))

#endif /* __KERNEL__ */

#endif /* _ASM_THREAD_INFO_H */

/*

 * 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/system.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);

	/* __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);

int

copy_thread(unsigned long clone_flags, unsigned long usp,

	    unsigned long unused, struct task_struct *p, struct pt_regs *regs)

{

	struct pt_regs *childregs;

	struct pt_regs *kregs;

	unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;

	struct thread_info *ti;

	unsigned long top_of_kernel_stack;

	top_of_kernel_stack = sp;

	p->set_child_tid = p->clear_child_tid = NULL;

	/* Copy registers */

	/* redzone */

	sp -= STACK_FRAME_OVERHEAD;

	sp -= sizeof(struct pt_regs);

	childregs = (struct pt_regs *)sp;

	/* Copy parent registers */

	*childregs = *regs;

	if ((childregs->sr & SPR_SR_SM) == 1) {

		/* for kernel thread, set `current_thread_info'

		 * and stackptr in new task

		 */

		childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;

		childregs->gpr[10] = (unsigned long)task_thread_info(p);

	} else {

		childregs->sp = usp;

	}

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

	/*

	 * The way this works is that at some point in the future

	 * some task will call _switch to switch to the new task.

	 * That will pop off the stack frame created below and start

	 * the new task running at ret_from_fork.  The new task will

	 * do some house keeping and then return from the fork or clone

	 * system call, using the stack frame created above.

	 */

	/* redzone */

	sp -= STACK_FRAME_OVERHEAD;

	sp -= sizeof(struct pt_regs);

	kregs = (struct pt_regs *)sp;

	ti = task_thread_info(p);

	ti->ksp = sp;

	/* kregs->sp must store the location of the 'pre-switch' kernel stack

	 * pointer... for a newly forked process, this is simply the top of

	 * the kernel stack.

	 */

	kregs->sp = top_of_kernel_stack;

	kregs->gpr[3] = (unsigned long)current;	/* arg to schedule_tail */

	kregs->gpr[10] = (unsigned long)task_thread_info(p);

	kregs->gpr[9] = (unsigned long)ret_from_fork;

	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 = regs->sr & ~SPR_SR_SM;

	set_fs(USER_DS);

	memset(regs->gpr, 0, sizeof(regs->gpr));

	regs->pc = pc;

	regs->sr = sr;

	regs->sp = sp;

/*	printk("start thread, ksp = %lx\n", current_thread_info()->ksp);*/

}

/* 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;

}

extern void _kernel_thread_helper(void);

void __noreturn kernel_thread_helper(int (*fn) (void *), void *arg)

{

	do_exit(fn(arg));

}

/*

 * Create a kernel thread.

 */

int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)

{

	struct pt_regs regs;

	memset(&regs, 0, sizeof(regs));

	regs.gpr[20] = (unsigned long)fn;

	regs.gpr[22] = (unsigned long)arg;

	regs.sr = mfspr(SPR_SR);

	regs.pc = (unsigned long)_kernel_thread_helper;

	return do_fork(flags | CLONE_VM | CLONE_UNTRACED,

		       0, &regs, 0, NULL, NULL);

}

/*

 * sys_execve() executes a new program.

 */

asmlinkage long _sys_execve(const char __user *name,

			    const char __user * const __user *argv,

			    const char __user * const __user *envp,

			    struct pt_regs *regs)

{

	int error;

	char *filename;

	filename = getname(name);

	error = PTR_ERR(filename);

	if (IS_ERR(filename))

		goto out;

	error = do_execve(filename, argv, envp, regs);

	putname(filename);

out:

	return error;

}

unsigned long get_wchan(struct task_struct *p)

{

	/* TODO */

	return 0;

}

int kernel_execve(const char *filename, char *const argv[], char *const envp[])

{

	register long __res asm("r11") = __NR_execve;

	register long __a asm("r3") = (long)(filename);

	register long __b asm("r4") = (long)(argv);

	register long __c asm("r5") = (long)(envp);

	__asm__ volatile ("l.sys 1"

			  : "=r" (__res), "=r"(__a), "=r"(__b), "=r"(__c)

			  : "0"(__res), "1"(__a), "2"(__b), "3"(__c)

			  : "r6", "r7", "r8", "r12", "r13", "r15",

			    "r17", "r19", "r21", "r23", "r25", "r27",

			    "r29", "r31");

	__asm__ volatile ("l.nop");

	return __res;

}