b34d83a709
versions of pthread_md.h have a special case of dereferencing a null
pointer. Clang warns about this with:
In file included from lib/libthr/arch/i386/i386/pthread_md.c:36:
lib/libthr/arch/i386/include/pthread_md.h:96:10: error: indirection of non-volatile null pointer will be deleted, not trap [-Werror,-Wnull-dereference]
return (TCB_GET32(tcb_self));
^~~~~~~~~~~~~~~~~~~
lib/libthr/arch/i386/include/pthread_md.h:73:13: note: expanded from:
: "m" (*(u_int *)(__tcb_offset(name)))); \
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
lib/libthr/arch/i386/include/pthread_md.h:96:10: note: consider using __builtin_trap() or qualifying pointer with 'volatile'
Since this indirection is done relative to the fs or gs segment, to
retrieve thread-specific data, it is an exception to the rule.
Therefore, add a volatile qualifier to tell the compiler we really want
to dereference a zero address.
MFC after: 1 week
104 lines
2.9 KiB
C
104 lines
2.9 KiB
C
/*-
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* Copyright (C) 2003 David Xu <davidxu@freebsd.org>
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* Copyright (c) 2001 Daniel Eischen <deischen@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Neither the name of the author nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Machine-dependent thread prototypes/definitions.
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*/
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#ifndef _PTHREAD_MD_H_
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#define _PTHREAD_MD_H_
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#include <stddef.h>
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#include <sys/types.h>
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#include <machine/sysarch.h>
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#define CPU_SPINWAIT __asm __volatile("pause")
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#define DTV_OFFSET offsetof(struct tcb, tcb_dtv)
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/*
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* Variant II tcb, first two members are required by rtld,
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* %fs points to the structure.
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*/
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struct tcb {
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struct tcb *tcb_self; /* required by rtld */
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void *tcb_dtv; /* required by rtld */
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struct pthread *tcb_thread;
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void *tcb_spare[1];
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};
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/*
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* Evaluates to the byte offset of the per-tcb variable name.
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*/
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#define __tcb_offset(name) __offsetof(struct tcb, name)
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/*
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* Evaluates to the type of the per-tcb variable name.
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*/
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#define __tcb_type(name) __typeof(((struct tcb *)0)->name)
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/*
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* Evaluates to the value of the per-tcb variable name.
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*/
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#define TCB_GET64(name) ({ \
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__tcb_type(name) __result; \
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\
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u_long __i; \
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__asm __volatile("movq %%fs:%1, %0" \
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: "=r" (__i) \
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: "m" (*(volatile u_long *)(__tcb_offset(name)))); \
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__result = (__tcb_type(name))__i; \
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\
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__result; \
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})
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struct tcb *_tcb_ctor(struct pthread *, int);
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void _tcb_dtor(struct tcb *tcb);
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static __inline void
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_tcb_set(struct tcb *tcb)
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{
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amd64_set_fsbase(tcb);
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}
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static __inline struct tcb *
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_tcb_get(void)
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{
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return (TCB_GET64(tcb_self));
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}
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static __inline struct pthread *
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_get_curthread(void)
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{
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return (TCB_GET64(tcb_thread));
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}
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#define HAS__UMTX_OP_ERR 1
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#endif
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