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Annotation of kernel/machdep/i386/thread.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /*
        !            26:  * Copyright (c) 1992 NeXT Computer, Inc.
        !            27:  *
        !            28:  * Intel386 Family:    Machine dependent thread state.
        !            29:  *
        !            30:  * HISTORY
        !            31:  *
        !            32:  * 30 September 1992 ? at NeXT
        !            33:  *     Moved tss out of pcb.
        !            34:  *
        !            35:  * 6 April 1992 ? at NeXT
        !            36:  *     Created.
        !            37:  */
        !            38: 
        !            39: #ifndef        _MACHDEP_I386_PCB_H_
        !            40: #define _MACHDEP_I386_PCB_H_
        !            41: 
        !            42: #import <kern/kernel_stack.h>
        !            43: 
        !            44: #import <architecture/i386/frame.h>
        !            45: #import <architecture/i386/fpu.h>
        !            46: 
        !            47: #import <machdep/i386/seg.h>
        !            48: #import <machdep/i386/regs.h>
        !            49: 
        !            50: /*
        !            51:  * Context information which is common
        !            52:  * to all threads in a task.  Each
        !            53:  * thread has its own copy of this
        !            54:  * information.
        !            55:  */    
        !            56: typedef struct pcb_common {
        !            57:     vm_offset_t                ldt;    /* a LINEAR address */
        !            58:     vm_size_t          ldt_size;
        !            59:     struct {
        !            60:        vm_offset_t             base;
        !            61:        vm_size_t               length;
        !            62:     }                  io_bmap;
        !            63:     lock_data_t                lock;
        !            64: } pcb_common_t;
        !            65: 
        !            66: /*
        !            67:  * Storage definition for a threads
        !            68:  * hardware task state segment.
        !            69:  * Threads which need an IO space
        !            70:  * bitmap for access to device
        !            71:  * registers from user mode need
        !            72:  * an externally allocated TSS.
        !            73:  */
        !            74: typedef union {
        !            75:     tss_t              internal;
        !            76:     struct tss_alloc {
        !            77:        vm_offset_t             base;
        !            78:        vm_size_t               length;
        !            79:     }                  external;
        !            80: } pcb_tss_t;
        !            81: 
        !            82: /*
        !            83:  * Thread state is saved in
        !            84:  * this format whenever an
        !            85:  * interrupt/trap/system call
        !            86:  * occurs.
        !            87:  */
        !            88: typedef struct thread_saved_state {
        !            89:     regs_t             regs;
        !            90:     unsigned int       trapno;
        !            91:     except_frame_t     frame;
        !            92: } thread_saved_state_t;
        !            93: 
        !            94: /*
        !            95:  * A thread uses a private save
        !            96:  * area as its kernel stack while
        !            97:  * executing in user mode.  After
        !            98:  * the user state is saved, it
        !            99:  * switches to the active kernel
        !           100:  * stack.  The save area must be
        !           101:  * large enough to hold the entire
        !           102:  * user state, plus enough for a
        !           103:  * kernel mode interrupt in case
        !           104:  * one occurs before the stack is
        !           105:  * switched.  In addition, if a
        !           106:  * call gate gets invoked with
        !           107:  * the TF (single step) flag set,
        !           108:  * the debug trap gets taken from
        !           109:  * kernel mode after the call
        !           110:  * frame gets saved but before the
        !           111:  * first instruction of the call
        !           112:  * gate handler gets executed.  Thus,
        !           113:  * an extra exception frame is needed
        !           114:  * for the worst case.
        !           115:  */
        !           116: typedef struct thread_save_area {
        !           117:     except_frame_t             sa_x;
        !           118:     thread_saved_state_t       sa_k;
        !           119:     thread_saved_state_t       sa_u;
        !           120: } thread_save_area_t;
        !           121: 
        !           122: /*
        !           123:  * Per-thread machine dependent
        !           124:  * context information.
        !           125:  */
        !           126: typedef struct pcb {
        !           127:     /*
        !           128:      * i386 Hardware Task State.
        !           129:      */
        !           130:     tss_t *            tss;
        !           131:     vm_size_t          tss_size;
        !           132:     pcb_tss_t          tss_store;
        !           133: 
        !           134:     /*
        !           135:      * The private area for saved user
        !           136:      * state is external to the pcb,
        !           137:      * and is created lazily.  This
        !           138:      * avoids wasting the space for
        !           139:      * kernel mode-only threads.
        !           140:      */
        !           141:     thread_save_area_t *save_area;
        !           142: 
        !           143:     /*
        !           144:      * Most threads use a common, static
        !           145:      * LDT.  Some threads have their own,
        !           146:      * which resides in the task virtual
        !           147:      * address space.
        !           148:      */        
        !           149:     vm_offset_t                ldt;    /* a LINEAR address */
        !           150:     vm_size_t          ldt_size;
        !           151:     
        !           152:     /*
        !           153:      * Floating point state is
        !           154:      * identical to the format
        !           155:      * written by the FSAVE instruction.
        !           156:      */
        !           157:     fp_state_t         fpstate;
        !           158: 
        !           159:     /*
        !           160:      * cthreads 'self' id
        !           161:      */ 
        !           162:     unsigned int       cthread_self;
        !           163:     
        !           164:     /*
        !           165:      * Private data structure for
        !           166:      * PC support.
        !           167:      */
        !           168:     struct PCprivate   *PCpriv;
        !           169: 
        !           170:     /*
        !           171:      * Boolean flags.
        !           172:      */
        !           173:     unsigned int
        !           174:     /* boolean_t */    trace           :1,
        !           175:                        fpvalid         :1,
        !           176:                        extern_tss      :1,
        !           177:                                        :0;
        !           178: } *pcb_t;
        !           179: 
        !           180: #define current_stack_pointer()                (stack_pointers[cpu_number()])
        !           181: 
        !           182: #define USER_REGS(thread)                                              \
        !           183:     ((thread)->pcb->save_area ?                                                \
        !           184:        (&(thread)->pcb->save_area->sa_u) :                             \
        !           185:            (void *)(thread_user_state(thread)))
        !           186:  
        !           187: #endif /* _MACHDEP_I386_PCB_H_ */

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