FreeBSD/Linux Kernel Cross Reference
sys/x86/include/tls.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (C) 2003 David Xu <davidxu@freebsd.org>
      * Copyright (c) 2001 Daniel Eischen <deischen@freebsd.org>
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Neither the name of the author nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #ifndef _MACHINE_TLS_H_
    #define _MACHINE_TLS_H_
    
    #include <x86/sysarch.h>
    
    #define TLS_VARIANT_II
    
    struct pthread;
    
    /*
     * Variant II tcb, first two members are required by rtld,
     * %fs (amd64) / %gs (i386) points to the structure.
     */
    struct tcb {
            struct tcb              *tcb_self;      /* required by rtld */
            uintptr_t               *tcb_dtv;       /* required by rtld */
            struct pthread          *tcb_thread;
    };
    
    #define TLS_DTV_OFFSET  0
    #ifdef __amd64__
    #define TLS_TCB_ALIGN   16
    #else
    #define TLS_TCB_ALIGN   4
    #endif
    #define TLS_TCB_SIZE    sizeof(struct tcb)
    #define TLS_TP_OFFSET   0
    
    static __inline void
    _tcb_set(struct tcb *tcb)
    {
    #ifdef __amd64__
            amd64_set_fsbase(tcb);
    #else
            i386_set_gsbase(tcb);
    #endif
    }
    
    static __inline struct tcb *
    _tcb_get(void)
    {
            struct tcb *tcb;
    
    #ifdef __amd64__
            __asm __volatile("movq %%fs:0, %0" : "=r" (tcb));
    #else
            __asm __volatile("movl %%gs:0, %0" : "=r" (tcb));
    #endif
            return (tcb);
    }
    
    #endif /* !_MACHINE_TLS_H_ */

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