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/* $OpenBSD: tcb.h,v 1.4 2012/02/18 21:43:28 fgsch Exp $ */
/*
* Copyright (c) 2011 Philip Guenther <guenther@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef _TCB_H_
#define _TCB_H_
/*
* We define the structure for the TCB, plus three macros:
* TCB_THREAD()
* Expands to a pointer-to-pthread rvalue that points
* to this thread's struct pthread
* TCB_ERRNOPTR()
* Expands to a pointer-to-int lvalue that points to
* this thread's errno
* TCB_INIT(tcb, thread, errnoptr)
* Expands to a code to initialize the TCB pointed to by
* its first argument
*
* <machine/tcb.h> must define the TLS_VARIANT macro. If it defines
* that to 1, then may also defined the macro
* THREAD_ERRNOPTR_OFFSET
* Byte offset in struct pthread of the pointer to the
* thread's errno
*
* By default, we get and set the TCB pointer for a thread using the
* __get_tcb() and __set_tcb() syscalls. If there's a faster way to do
* either of those, <machine/tcb.h> should define the macros
* TCB_SET(tcb)
* Set the TCB pointer for this thread
* TCB_GET()
* Return the TCB pointer for this thread
* If it defines TCB_GET, then it must also define:
* TCB_GET_MEMBER(member)
* Return the pointer in the 'member' slot in the TCB
*/
#include <machine/tcb.h>
#include <stddef.h>
struct pthread;
void *__get_tcb(void);
void __set_tcb(void *);
#ifdef TCB_GET_MEMBER
#define TCB_THREAD() ((struct pthread *)TCB_GET_MEMBER(tcb_thread))
#else
#define TCB_THREAD() \
(((struct thread_control_block *)__get_tcb())->tcb_thread)
#endif
#if TLS_VARIANT == 1
/*
* Small TCB, with TLS data after the TCB.
* Errno pointer stored in struct pthread
*/
struct thread_control_block {
void *tcb_dtv; /* internal to the runtime linker */
struct pthread *tcb_thread;
};
#ifndef THREAD_ERRNOPTR_OFFSET
# define THREAD_ERRNOPTR_OFFSET offsetof(struct pthread, errno_ptr)
#endif
#define __ERRNOPTR(thread) \
(((int **)(thread))[THREAD_ERRNOPTR_OFFSET / sizeof(int *)])
#define TCB_ERRNOPTR() \
__ERRNOPTR(TCB_THREAD())
#define TCB_INIT(tcb, thread, errnoptr) \
do { \
(tcb)->tcb_dtv = 0; \
(tcb)->tcb_thread = (thread); \
__ERRNOPTR(thread) = (errnoptr); \
} while (0)
#elif TLS_VARIANT == 2
/*
* Large TCB, with TLS data before the TCB (i.e., negative offsets)
* Errno pointer stored in the TCB
*/
struct thread_control_block {
struct thread_control_block *__tcb_self;
void *tcb_dtv; /* internal to the runtime linker */
struct pthread *tcb_thread;
int *__tcb_errno;
};
#ifdef TCB_GET_MEMBER
#define TCB_ERRNOPTR() ((int *)TCB_GET_MEMBER(__tcb_errno))
#else
#define TCB_ERRNOPTR() \
(((struct thread_control_block *)__get_tcb())->__tcb_errno)
#endif
#define TCB_INIT(tcb, thread, errnoptr) \
do { \
(tcb)->__tcb_self = (tcb); \
(tcb)->tcb_dtv = 0; \
(tcb)->tcb_thread = (thread); \
(tcb)->__tcb_errno = (errnoptr); \
} while (0)
#else
# error "unknown TLS variant"
#endif
/* If there isn't a better way, use the default */
#ifndef TCB_SET
#define TCB_SET(tcb) __set_tcb(tcb)
#endif
#if 0
void *_rtld_allocate_tls(void *, size_t, size_t);
void _rtld_free_tls(void *, size_t, size_t);
#else
/*
* XXX Until we have these in ld.so and support __thread, just use
* malloc/free. The main thread's TCB cannot be allocated or freed with these.
*/
#define _rtld_allocate_tls(old, size, align) malloc(size)
#define _rtld_free_tls(old, size, align) free(old)
#endif
#endif /* _TCB_H_ */
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