niansa-misc/glibc
1
0
Fork 0
mirror of git://sourceware.org/git/glibc.git synced 2025-03-06 20:58:33 +01:00
Code Issues Projects Releases Packages Wiki Activity

Add Linux 'extra TLS'

Browse source 
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>
This commit is contained in:
Michael Jeanson 2024-08-01 11:10:49 -04:00
parent 0e411c5d30
commit 304221775c
1 changed files with 71 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

71
sysdeps/unix/sysv/linux/dl-extra_tls.h Normal file
View file

@ -0,0 +1,71 @@
/* 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