qemu/qemu-tls.h

53 lines
1.9 KiB
C

/*
* Abstraction layer for defining and using TLS variables
*
* Copyright (c) 2011 Red Hat, Inc
* Copyright (c) 2011 Linaro Limited
*
* Authors:
* Paolo Bonzini <pbonzini@redhat.com>
* Peter Maydell <peter.maydell@linaro.org>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef QEMU_TLS_H
#define QEMU_TLS_H
/* Per-thread variables. Note that we only have implementations
* which are really thread-local on Linux; the dummy implementations
* define plain global variables.
*
* This means that for the moment use should be restricted to
* per-VCPU variables, which are OK because:
* - the only -user mode supporting multiple VCPU threads is linux-user
* - TCG system mode is single-threaded regarding VCPUs
* - KVM system mode is multi-threaded but limited to Linux
*
* TODO: proper implementations via Win32 .tls sections and
* POSIX pthread_getspecific.
*/
#ifdef __linux__
#define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
#define DEFINE_TLS(type, x) __thread __typeof__(type) tls__##x
#define tls_var(x) tls__##x
#else
/* Dummy implementations which define plain global variables */
#define DECLARE_TLS(type, x) extern DEFINE_TLS(type, x)
#define DEFINE_TLS(type, x) __typeof__(type) tls__##x
#define tls_var(x) tls__##x
#endif
#endif