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| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2020-07-06 10:21:16 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2020-07-06 10:21:16 +0200 |
| commit | 0c76fc3c2b346dc5401dc055d97d4279632b0fb3 (patch) | |
| tree | 67d7a99ad801c38a137fbb9d08ac54137bb901b9 /sysdeps/unix/sysv/linux/x86/bits/rseq.h | |
| parent | f9cf87353772ca370b7bb901d86365a564fba49f (diff) | |
| download | glibc-0c76fc3c2b346dc5401dc055d97d4279632b0fb3.tar.gz glibc-0c76fc3c2b346dc5401dc055d97d4279632b0fb3.tar.xz glibc-0c76fc3c2b346dc5401dc055d97d4279632b0fb3.zip | |
Linux: Perform rseq registration at C startup and thread creation
Register rseq TLS for each thread (including main), and unregister for each thread (excluding main). "rseq" stands for Restartable Sequences. See the rseq(2) man page proposed here: https://lkml.org/lkml/2018/9/19/647 Those are based on glibc master branch commit 3ee1e0ec5c. The rseq system call was merged into Linux 4.18. The TLS_STATIC_SURPLUS define is increased to leave additional room for dlopen'd initial-exec TLS, which keeps elf/tst-auditmany working. The increase (76 bytes) is larger than 32 bytes because it has not been increased in quite a while. The cost in terms of additional TLS storage is quite significant, but it will also obscure some initial-exec-related dlopen failures.
Diffstat (limited to 'sysdeps/unix/sysv/linux/x86/bits/rseq.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/x86/bits/rseq.h | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/x86/bits/rseq.h b/sysdeps/unix/sysv/linux/x86/bits/rseq.h new file mode 100644 index 0000000000..f801d5d0a1 --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/bits/rseq.h @@ -0,0 +1,30 @@ +/* Restartable Sequences Linux x86 architecture header. + Copyright (C) 2020 Free Software Foundation, Inc. + + 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 _SYS_RSEQ_H +# error "Never use <bits/rseq.h> directly; include <sys/rseq.h> instead." +#endif + +/* RSEQ_SIG is a signature required before each abort handler code. + + RSEQ_SIG is used with the following reserved undefined instructions, which + trap in user-space: + + x86-32: 0f b9 3d 53 30 05 53 ud1 0x53053053,%edi + x86-64: 0f b9 3d 53 30 05 53 ud1 0x53053053(%rip),%edi */ + +#define RSEQ_SIG 0x53053053 |