glibc/sysdeps/generic/tls.h

71 lines
2.4 KiB
C

/* Definition for thread-local data handling. Generic version.
Copyright (C) 2002-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* An architecture-specific version of this file has to defined a
number of symbols:
TCB_ALIGNMENT
Alignment of THREAD_SELF (struct pthread *) and the thread
pointer.
TLS_TCB_AT_TP or TLS_DTV_AT_TP
The presence of one of these symbols signals which variant of
the TLS ABI is used. There are in the moment two variants
available:
* the thread pointer points to a thread control block
* the thread pointer points to the dynamic thread vector
TLS_TCB_SIZE
This is the size of the thread control block structure. How
this is actually defined depends on the ABI. The thread control
block could be internal descriptor of the thread library or
just a data structure which allows finding the DTV.
TLS_INIT_TCB_SIZE
Similarly, but this value is only used at startup and in the
dynamic linker itself. There are no threads in use at that time.
INSTALL_DTV(tcb, init_dtv)
This macro must install the given initial DTV into the thread control
block TCB. The normal runtime functionality must then be able to
use the value.
TLS_INIT_TP(tcb)
This macro must initialize the thread pointer to enable normal TLS
operation. The parameter is a pointer to the thread control block.
ld.so calls this macro once.
THREAD_DTV()
This macro returns the address of the DTV of the current thread.
This normally is done using the thread register which points
to the dtv or the TCB (from which the DTV can found).
*/