root/include/asm-m68k/processor.h

INCLUDED FROM

DEFINITIONS

1. rdusp
2. wrusp
3. start_thread
4. release_thread
5. exit_thread

/*
 * include/asm-m68k/processor.h
 *
 * Copyright (C) 1995 Hamish Macdonald
 */

#ifndef __ASM_M68K_PROCESSOR_H
#define __ASM_M68K_PROCESSOR_H

/*
 * Default implementation of macro that returns current
 * instruction pointer ("program counter").
 */
#define current_text_addr() ({ __label__ _l; _l: &&_l;})

#include <linux/thread_info.h>
#include <asm/segment.h>
#include <asm/fpu.h>
#include <asm/ptrace.h>

static inline unsigned long rdusp(void)
{
        unsigned long usp;

        __asm__ __volatile__("move %/usp,%0" : "=a" (usp));
        return usp;
}

static inline void wrusp(unsigned long usp)
{
        __asm__ __volatile__("move %0,%/usp" : : "a" (usp));
}

/*
 * User space process size: 3.75GB. This is hardcoded into a few places,
 * so don't change it unless you know what you are doing.
 */
#ifndef CONFIG_SUN3
#define TASK_SIZE       (0xF0000000UL)
#else
#define TASK_SIZE       (0x0E000000UL)
#endif

#ifdef __KERNEL__
#define STACK_TOP       TASK_SIZE
#define STACK_TOP_MAX   STACK_TOP
#endif

/* This decides where the kernel will search for a free chunk of vm
 * space during mmap's.
 */
#ifndef CONFIG_SUN3
#define TASK_UNMAPPED_BASE      0xC0000000UL
#else
#define TASK_UNMAPPED_BASE      0x0A000000UL
#endif
#define TASK_UNMAPPED_ALIGN(addr, off)  PAGE_ALIGN(addr)

struct thread_struct {
        unsigned long  ksp;             /* kernel stack pointer */
        unsigned long  usp;             /* user stack pointer */
        unsigned short sr;              /* saved status register */
        unsigned short fs;              /* saved fs (sfc, dfc) */
        unsigned long  crp[2];          /* cpu root pointer */
        unsigned long  esp0;            /* points to SR of stack frame */
        unsigned long  faddr;           /* info about last fault */
        int            signo, code;
        unsigned long  fp[8*3];
        unsigned long  fpcntl[3];       /* fp control regs */
        unsigned char  fpstate[FPSTATESIZE];  /* floating point state */
        struct thread_info info;
};

#define INIT_THREAD  {                                                  \
        .ksp    = sizeof(init_stack) + (unsigned long) init_stack,      \
        .sr     = PS_S,                                                 \
        .fs     = __KERNEL_DS,                                          \
        .info   = INIT_THREAD_INFO(init_task),                          \
}

/*
 * Do necessary setup to start up a newly executed thread.
 */
static inline void start_thread(struct pt_regs * regs, unsigned long pc,
                                unsigned long usp)
{
        /* reads from user space */
        set_fs(USER_DS);

        regs->pc = pc;
        regs->sr &= ~0x2000;
        wrusp(usp);
}

/* Forward declaration, a strange C thing */
struct task_struct;

/* Free all resources held by a thread. */
static inline void release_thread(struct task_struct *dead_task)
{
}

/* Prepare to copy thread state - unlazy all lazy status */
#define prepare_to_copy(tsk)    do { } while (0)

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

/*
 * Free current thread data structures etc..
 */
static inline void exit_thread(void)
{
}

extern unsigned long thread_saved_pc(struct task_struct *tsk);

unsigned long get_wchan(struct task_struct *p);

#define KSTK_EIP(tsk)   \
    ({                  \
        unsigned long eip = 0;   \
        if ((tsk)->thread.esp0 > PAGE_SIZE && \
            (virt_addr_valid((tsk)->thread.esp0))) \
              eip = ((struct pt_regs *) (tsk)->thread.esp0)->pc; \
        eip; })
#define KSTK_ESP(tsk)   ((tsk) == current ? rdusp() : (tsk)->thread.usp)

#define cpu_relax()     barrier()

#endif