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/* $OpenBSD: tib.h,v 1.2 2016/03/20 02:30:28 guenther Exp $ */
/*
* Copyright (c) 2011,2014 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.
*/
/*
* Thread Information Block (TIB) and Thread Local Storage (TLS) handling
* (the TCB, Thread Control Block, is part of the TIB)
*/
#ifndef _TIB_H_
#define _TIB_H_
#include <sys/types.h>
#include <machine/tcb.h>
#include <stddef.h>
/*
* This header defines struct tib and at least eight macros:
* TLS_VARIANT
* Either 1 or 2 (Actually defined by <machine/tcb.h>)
*
* TCB_SET(tcb)
* Set the TCB pointer for this thread to 'tcb'
*
* TCB_GET()
* Return the TCB pointer for this thread
*
* TCB_TO_TIB(tcb)
* Given a TCB pointer, return the matching TIB pointer
*
* TIB_TO_TCB(tib)
* Given a TIB pointer, return the matching TCB pointer
*
* TIB_INIT(tib, dtv)
* Initializes a TIB for a new thread, using the supplied
* value for the dtv pointer
*
* TIB_TO_THREAD(tib)
* Given a TIB pointer, return a pointer to the struct pthread
*
* TIB_GET()
* Short-hand for TCB_TO_TIB(TCB_GET())
*
* TIB_THREAD()
* Returns a pointer to this thread's struct pthread
*
* TIB_EXTRA_ALIGN
* On TLS varaint 2 archs, what alignment is sufficient
* for the extra space that will be used for struct pthread?
*
* The following functions are provided by either ld.so (dynamic) or
* libc (static) for allocating and freeing a common memory block that
* will hold both the TIB and the pthread structure:
* _dl_allocate_tib(sizeof(struct pthread), flags)
* Allocates a combined TIB and pthread memory region.
* The first argument is the amount of space to reserve
* for the pthread structure; the second argument is
* either zero or DAT_UPDATE_CURRENT, the latter meaning
* this call is to update/replace the current thread's
* TIB. Returns a pointer to the TIB inside the
* allocated block.
*
* _dl_free_tib(tib, sizeof(struct pthread))
* Frees a TIB and pthread block previously allocated
* with _dl_allocate_tls(). Must be passed the return
* value of that previous call.
*/
/*
* Regarding <machine/tcb.h>:
* - it must define the TLS_VARIANT macro
* - if there's a faster way to get or set the TCB pointer for the thread
* than the __{get,set}_tcb() syscalls, it should define either or both
* the TCB_{GET,SET} macros to do so.
*/
/* If <machine/tcb.h> doesn't provide a better way, then use the default */
#ifdef TCB_GET
# define TCB_HAVE_MD_GET 1
#else
# define TCB_GET() __get_tcb()
#endif
#ifdef TCB_SET
# define TCB_HAVE_MD_SET 1
#else
# define TCB_SET(tcb) __set_tcb(tcb)
#endif
#if TLS_VARIANT == 1
/*
* ABI specifies that the static TLS data starts two words after the
* (notional) thread pointer, with the first of those two words being
* the TLS dtv pointer. The other (second) word is reserved for the
* implementation, so we place the thread's locale there, but we place
* our thread bits before the TCB, at negative offsets from the
* TCB pointer. Ergo, memory is laid out, low to high, as:
*
* [pthread structure]
* TIB {
* int cancel_flags
* int cancel_requested
* int errno
* void *locale
* TCB {
* void *dtv
* struct pthread *thread
* }
* }
* static TLS data
*/
struct tib {
#ifdef __LP64__
int __tib_padding; /* padding for 8byte alignment */
#endif
int tib_cancel_flags;
int tib_cancel;
int tib_errno;
void *tib_locale;
void *tib_dtv; /* internal to the runtime linker */
void *tib_thread;
};
#ifdef __LP64__
# define _TIB_PREP(tib) ((void)((tib)->__tib_padding = 0))
#endif
#define _TIBO_PTHREAD (- _ALIGN(sizeof(struct pthread)))
#elif TLS_VARIANT == 2
/*
* ABI specifies that the static TLS data occupies the memory before
* the TCB pointer, at negative offsets, and that on i386 and amd64
* the word the TCB points to contains a pointer to itself. So,
* we place errno and our thread bits after that. Memory is laid
* out, low to high, as:
* static TLS data
* TIB {
* TCB {
* self pointer [i386/amd64 only]
* void *dtv
* }
* struct pthread *thread
* void *locale
* int errno
* int cancel_count_flags
* int cancel_requested
* }
* [pthread structure]
*/
struct tib {
#if defined(__i386) || defined(__amd64)
struct tib *__tib_self;
# define __tib_tcb __tib_self
#endif
void *tib_dtv; /* internal to the runtime linker */
void *tib_thread;
void *tib_locale;
int tib_errno;
int tib_cancel; /* set to request cancelation */
int tib_cancel_flags;
#if defined(__LP64__) || defined(__i386)
int __tib_padding; /* padding for 8byte alignment */
#endif
};
#define _TIBO_PTHREAD _ALIGN(sizeof(struct tib))
#if defined(__i386) || defined(__amd64)
# define _TIB_PREP(tib) \
((void)((tib)->__tib_self = (tib), (tib)->__tib_padding = 0))
#elif defined(__LP64__)
# define _TIB_PREP(tib) ((void)((tib)->__tib_padding = 0))
#endif
#define TIB_EXTRA_ALIGN sizeof(void *)
#else
# error "unknown TLS variant"
#endif
/* nothing to do by default */
#ifndef _TIB_PREP
# define _TIB_PREP(tib) ((void)0)
#endif
#define TIB_INIT(tib, dtv, thread) do { \
(tib)->tib_thread = (thread); \
(tib)->tib_locale = NULL; \
(tib)->tib_cancel_flags = 0; \
(tib)->tib_cancel = 0; \
(tib)->tib_dtv = (dtv); \
(tib)->tib_errno = 0; \
_TIB_PREP(tib); \
} while (0)
#ifndef __tib_tcb
# define __tib_tcb tib_dtv
#endif
#define _TIBO_TCB offsetof(struct tib, __tib_tcb)
#define TCB_TO_TIB(tcb) ((struct tib *)((char *)(tcb) - _TIBO_TCB))
#define TIB_TO_TCB(tib) ((char *)(tib) + _TIBO_TCB)
#define TIB_TO_THREAD(tib) ((struct pthread *)(tib)->tib_thread)
#define TIB_GET() TCB_TO_TIB(TCB_GET())
#define TCB_THREAD() TIB_TO_THREAD(TIB_GET())
__BEGIN_DECLS
void *_dl_allocate_tib(size_t _extra) __dso_public;
void _dl_free_tib(void *_tib, size_t _extra) __dso_public;
/* The actual syscalls */
void *__get_tcb(void);
void __set_tcb(void *_tcb);
__END_DECLS
#endif /* _TIB_H_ */
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