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/*

 * 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