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/* thread_info.h: i386 low-level thread information
 *
 * Copyright (C) 2002  David Howells (dhowells@redhat.com)
 * - Incorporating suggestions made by Linus Torvalds and Dave Miller
 */

#ifndef _ASM_THREAD_INFO_H
#define _ASM_THREAD_INFO_H

#ifdef __KERNEL__

#ifndef __ASSEMBLY__
#include <asm/processor.h>
#endif

/*
 * 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__

struct thread_info {
        struct task_struct      *task;          /* main task structure */
        struct exec_domain      *exec_domain;   /* execution domain */
        unsigned long           flags;          /* low level flags */
        unsigned long           status;         /* thread-synchronous flags */
        __u32                   cpu;            /* current CPU */
        __s32                   preempt_count; /* 0 => preemptable, <0 => BUG */

        mm_segment_t            addr_limit;     /* thread address space:
                                                   0-0xBFFFFFFF for user-thead
                                                   0-0xFFFFFFFF for kernel-thread
                                                */
        struct restart_block    restart_block;

        __u8                    supervisor_stack[0];
};

#else /* !__ASSEMBLY__ */

/* offsets into the thread_info struct for assembly code access */
#define TI_TASK         0x00000000
#define TI_EXEC_DOMAIN  0x00000004
#define TI_FLAGS        0x00000008
#define TI_STATUS       0x0000000C
#define TI_CPU          0x00000010
#define TI_PRE_COUNT    0x00000014
#define TI_ADDR_LIMIT   0x00000018
#define TI_RESTART_BLOCK 0x000001C

#endif

#define PREEMPT_ACTIVE          0x4000000

/*
 * 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,    \
        },                                      \
}

#define init_thread_info        (init_thread_union.thread_info)
#define init_stack              (init_thread_union.stack)

/* how to get the thread information struct from C */
static inline struct thread_info *current_thread_info(void)
{
        struct thread_info *ti;
        __asm__("andl %%esp,%0; ":"=r" (ti) : "0" (~8191UL));
        return ti;
}

/* thread information allocation */
#define THREAD_SIZE (2*PAGE_SIZE)
#define alloc_thread_info(task) ((struct thread_info *)kmalloc(THREAD_SIZE, GFP_KERNEL))
#define free_thread_info(info)  kfree(info)
#define get_thread_info(ti) get_task_struct((ti)->task)
#define put_thread_info(ti) put_task_struct((ti)->task)

#else /* !__ASSEMBLY__ */

/* how to get the thread information struct from ASM */
#define GET_THREAD_INFO(reg) \
        movl $-8192, reg; \
        andl %esp, reg

#endif

/*
 * 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_IRET                5       /* return with iret */
#define TIF_POLLING_NRFLAG      16      /* true if poll_idle() is polling TIF_NEED_RESCHED */

#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_IRET               (1<<TIF_IRET)
#define _TIF_POLLING_NRFLAG     (1<<TIF_POLLING_NRFLAG)

#define _TIF_WORK_MASK          0x0000FFFE      /* work to do on interrupt/exception return */
#define _TIF_ALLWORK_MASK       0x0000FFFF      /* work to do on any return to u-space */

/*
 * Thread-synchronous status.
 *
 * This is different from the flags in that nobody else
 * ever touches our thread-synchronous status, so we don't
 * have to worry about atomic accesses.
 */
#define TS_USEDFPU              0x0001  /* FPU was used by this task this quantum (SMP) */

#endif /* __KERNEL__ */

#endif /* _ASM_THREAD_INFO_H */