mirror of
https://sourceware.org/git/glibc.git
synced 2025-11-03 20:53:13 +03:00
304221775c
Add the Linux implementation of 'extra TLS' which will allocate space for the rseq area at the end of the TLS blocks in allocation order. Signed-off-by: Michael Jeanson <mjeanson@efficios.com> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: Florian Weimer <fweimer@redhat.com>
72 lines
2.4 KiB
C
72 lines
2.4 KiB
C
/* extra tls block utils for the dynamic linker. Linux version.
|
|
Copyright (C) 2025 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/>. */
|
|
|
|
#ifndef _DL_EXTRA_TLS_H
|
|
#define _DL_EXTRA_TLS_H 1
|
|
|
|
#include <stddef.h>
|
|
#include <sys/rseq.h>
|
|
#include <rseq-internal.h>
|
|
#include <elf/dl-tunables.h>
|
|
|
|
/* Returns the size of the extra TLS block, it must always be a multiple of the
|
|
alignment. */
|
|
static inline size_t
|
|
_dl_extra_tls_get_size (void)
|
|
{
|
|
bool do_rseq = TUNABLE_GET_FULL (glibc, pthread, rseq, int, NULL);
|
|
if (do_rseq)
|
|
{
|
|
/* Make sure the rseq area size is at least the minimum ABI size and a
|
|
multiple of the requested aligment. */
|
|
return roundup (MAX (_rseq_size, RSEQ_AREA_SIZE_INITIAL), _rseq_align);
|
|
}
|
|
|
|
/* Even when disabled by tunable, an rseq area will be allocated to allow
|
|
application code to test the registration status with 'rseq->cpu_id >= 0'.
|
|
Default to the rseq ABI minimum size, this will ensure we don't use more
|
|
TLS than necessary. */
|
|
return RSEQ_AREA_SIZE_INITIAL;
|
|
}
|
|
|
|
/* Returns the alignment requirements of the extra TLS block. */
|
|
static inline size_t
|
|
_dl_extra_tls_get_align (void)
|
|
{
|
|
bool do_rseq = TUNABLE_GET_FULL (glibc, pthread, rseq, int, NULL);
|
|
if (do_rseq)
|
|
{
|
|
return _rseq_align;
|
|
}
|
|
|
|
/* Even when disabled by tunable, an rseq area will be allocated to allow
|
|
application code to test the registration status with 'rseq->cpu_id >= 0'.
|
|
Default to the rseq ABI minimum alignment, this will ensure we don't use
|
|
more TLS than necessary. */
|
|
return RSEQ_MIN_ALIGN;
|
|
}
|
|
|
|
/* Record the offset of the extra TLS block from the thread pointer. */
|
|
static inline void
|
|
_dl_extra_tls_set_offset (ptrdiff_t tls_offset)
|
|
{
|
|
_rseq_offset = tls_offset;
|
|
}
|
|
|
|
#endif
|