Register rseq(2) 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
This patch is based on glibc commit a502c5294. The rseq(2) system call
was merged into Linux 4.18.
Signed-off-by: Mathieu Desnoyers <[email protected]>
CC: Carlos O'Donell <[email protected]>
CC: Florian Weimer <[email protected]>
CC: Joseph Myers <[email protected]>
CC: Szabolcs Nagy <[email protected]>
CC: Thomas Gleixner <[email protected]>
CC: Ben Maurer <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: "Paul E. McKenney" <[email protected]>
CC: Boqun Feng <[email protected]>
CC: Will Deacon <[email protected]>
CC: Dave Watson <[email protected]>
CC: Paul Turner <[email protected]>
CC: Rich Felker <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
---
Changes since v1:
- Move __rseq_refcount to an extra field at the end of __rseq_abi to
eliminate one symbol.
All libraries/programs which try to register rseq (glibc,
early-adopter applications, early-adopter libraries) should use the
rseq refcount. It becomes part of the ABI within a user-space
process, but it's not part of the ABI shared with the kernel per se.
- Restructure how this code is organized so glibc keeps building on
non-Linux targets.
- Use non-weak symbol for __rseq_abi.
- Move rseq registration/unregistration implementation into its own
nptl/rseq.c compile unit.
- Move __rseq_abi symbol under GLIBC_2.29.
Changes since v2:
- Move __rseq_refcount to its own symbol, which is less ugly than
trying to play tricks with the rseq uapi.
- Move __rseq_abi from nptl to csu (C start up), so it can be used
across glibc, including memory allocator and sched_getcpu(). The
__rseq_refcount symbol is kept in nptl, because there is no reason
to use it elsewhere in glibc.
Changes since v3:
- Set __rseq_refcount TLS to 1 on register/set to 0 on unregister
because glibc is the first/last user.
- Unconditionally register/unregister rseq at thread start/exit, because
glibc is the first/last user.
- Add missing abilist items.
- Rebase on glibc master commit a502c5294.
- Add NEWS entry.
---
NEWS | 6 ++
csu/Makefile | 2 +-
csu/Versions | 3 +
csu/rseq.c | 38 ++++++++++
nptl/Makefile | 2 +-
nptl/Versions | 4 ++
nptl/nptl-init.c | 3 +
nptl/pthreadP.h | 3 +
nptl/pthread_create.c | 8 +++
nptl/rseq.c | 42 +++++++++++
sysdeps/nptl/rseq-internal.h | 34 +++++++++
sysdeps/unix/sysv/linux/aarch64/libc.abilist | 1 +
.../sysv/linux/aarch64/libpthread.abilist | 1 +
sysdeps/unix/sysv/linux/alpha/libc.abilist | 1 +
.../unix/sysv/linux/alpha/libpthread.abilist | 1 +
sysdeps/unix/sysv/linux/arm/libc.abilist | 1 +
.../unix/sysv/linux/arm/libpthread.abilist | 1 +
sysdeps/unix/sysv/linux/hppa/libc.abilist | 1 +
.../unix/sysv/linux/hppa/libpthread.abilist | 1 +
sysdeps/unix/sysv/linux/i386/libc.abilist | 1 +
.../unix/sysv/linux/i386/libpthread.abilist | 1 +
sysdeps/unix/sysv/linux/ia64/libc.abilist | 1 +
.../unix/sysv/linux/ia64/libpthread.abilist | 1 +
.../sysv/linux/m68k/coldfire/libc.abilist | 1 +
.../linux/m68k/coldfire/libpthread.abilist | 1 +
.../unix/sysv/linux/m68k/m680x0/libc.abilist | 1 +
.../sysv/linux/m68k/m680x0/libpthread.abilist | 1 +
.../unix/sysv/linux/microblaze/libc.abilist | 1 +
.../sysv/linux/microblaze/libpthread.abilist | 1 +
.../sysv/linux/mips/mips32/fpu/libc.abilist | 1 +
.../sysv/linux/mips/mips32/libpthread.abilist | 1 +
.../sysv/linux/mips/mips32/nofpu/libc.abilist | 1 +
.../sysv/linux/mips/mips64/libpthread.abilist | 1 +
.../sysv/linux/mips/mips64/n32/libc.abilist | 1 +
.../sysv/linux/mips/mips64/n64/libc.abilist | 1 +
sysdeps/unix/sysv/linux/nios2/libc.abilist | 1 +
.../unix/sysv/linux/nios2/libpthread.abilist | 1 +
.../linux/powerpc/powerpc32/fpu/libc.abilist | 1 +
.../powerpc/powerpc32/libpthread.abilist | 1 +
.../powerpc/powerpc32/nofpu/libc.abilist | 1 +
.../linux/powerpc/powerpc64/libc-le.abilist | 1 +
.../sysv/linux/powerpc/powerpc64/libc.abilist | 1 +
.../powerpc/powerpc64/libpthread-le.abilist | 1 +
.../powerpc/powerpc64/libpthread.abilist | 1 +
.../unix/sysv/linux/riscv/rv64/libc.abilist | 1 +
.../sysv/linux/riscv/rv64/libpthread.abilist | 1 +
sysdeps/unix/sysv/linux/rseq-internal.h | 71 +++++++++++++++++++
.../unix/sysv/linux/s390/s390-32/libc.abilist | 1 +
.../linux/s390/s390-32/libpthread.abilist | 1 +
.../unix/sysv/linux/s390/s390-64/libc.abilist | 1 +
.../linux/s390/s390-64/libpthread.abilist | 1 +
sysdeps/unix/sysv/linux/sh/libc.abilist | 1 +
sysdeps/unix/sysv/linux/sh/libpthread.abilist | 1 +
.../sysv/linux/sparc/sparc32/libc.abilist | 1 +
.../linux/sparc/sparc32/libpthread.abilist | 1 +
.../sysv/linux/sparc/sparc64/libc.abilist | 1 +
.../linux/sparc/sparc64/libpthread.abilist | 1 +
.../unix/sysv/linux/x86_64/64/libc.abilist | 1 +
.../sysv/linux/x86_64/64/libpthread.abilist | 1 +
.../unix/sysv/linux/x86_64/x32/libc.abilist | 1 +
.../sysv/linux/x86_64/x32/libpthread.abilist | 1 +
61 files changed, 263 insertions(+), 2 deletions(-)
create mode 100644 csu/rseq.c
create mode 100644 nptl/rseq.c
create mode 100644 sysdeps/nptl/rseq-internal.h
create mode 100644 sysdeps/unix/sysv/linux/rseq-internal.h
diff --git a/NEWS b/NEWS
index f488821af1..b238eaa391 100644
--- a/NEWS
+++ b/NEWS
@@ -35,6 +35,12 @@ Major new features:
different directory. This is a GNU extension and similar to the
Solaris function of the same name.
+* Support for automatically registering threads with the Linux rseq(2)
+ system call has been added. This system call is implemented starting
+ from Linux 4.18. In order to be activated, it requires that glibc is built
+ against kernel headers that include this system call, and that glibc
+ detects availability of that system call at runtime.
+
Deprecated and removed features, and other changes affecting compatibility:
* The glibc.tune tunable namespace has been renamed to glibc.cpu and the
diff --git a/csu/Makefile b/csu/Makefile
index 88fc77662e..81d471587f 100644
--- a/csu/Makefile
+++ b/csu/Makefile
@@ -28,7 +28,7 @@ include ../Makeconfig
routines = init-first libc-start $(libc-init) sysdep version check_fds \
libc-tls elf-init dso_handle
-aux = errno
+aux = errno rseq
elide-routines.os = libc-tls
static-only-routines = elf-init
csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
diff --git a/csu/Versions b/csu/Versions
index 43010c3443..0f44ebf991 100644
--- a/csu/Versions
+++ b/csu/Versions
@@ -7,6 +7,9 @@ libc {
# New special glibc functions.
gnu_get_libc_release; gnu_get_libc_version;
}
+ GLIBC_2.29 {
+ __rseq_abi;
+ }
GLIBC_PRIVATE {
errno;
}
diff --git a/csu/rseq.c b/csu/rseq.c
new file mode 100644
index 0000000000..ccc88e4582
--- /dev/null
+++ b/csu/rseq.c
@@ -0,0 +1,38 @@
+/* Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Mathieu Desnoyers <[email protected]>, 2018.
+
+ 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdint.h>
+
+enum libc_rseq_cpu_id_state {
+ LIBC_RSEQ_CPU_ID_UNINITIALIZED = -1,
+ LIBC_RSEQ_CPU_ID_REGISTRATION_FAILED = -2,
+};
+
+/* linux/rseq.h defines struct rseq as aligned on 32 bytes. The kernel ABI
+ size is 20 bytes. */
+struct libc_rseq {
+ uint32_t cpu_id_start;
+ uint32_t cpu_id;
+ uint64_t rseq_cs;
+ uint32_t flags;
+} __attribute__ ((aligned(4 * sizeof(uint64_t))));
+
+__attribute__ ((weak))
+__thread volatile struct libc_rseq __rseq_abi = {
+ .cpu_id = LIBC_RSEQ_CPU_ID_UNINITIALIZED,
+};
diff --git a/nptl/Makefile b/nptl/Makefile
index 49b6faa330..3a5dc80c65 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -145,7 +145,7 @@ libpthread-routines = nptl-init nptlfreeres vars events version pt-interp \
mtx_destroy mtx_init mtx_lock mtx_timedlock \
mtx_trylock mtx_unlock call_once cnd_broadcast \
cnd_destroy cnd_init cnd_signal cnd_timedwait cnd_wait \
- tss_create tss_delete tss_get tss_set
+ tss_create tss_delete tss_get tss_set rseq
# pthread_setuid pthread_seteuid pthread_setreuid \
# pthread_setresuid \
# pthread_setgid pthread_setegid pthread_setregid \
diff --git a/nptl/Versions b/nptl/Versions
index e7f691da7a..f7890f73fc 100644
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -277,6 +277,10 @@ libpthread {
cnd_timedwait; cnd_wait; tss_create; tss_delete; tss_get; tss_set;
}
+ GLIBC_2.29 {
+ __rseq_refcount;
+ }
+
GLIBC_PRIVATE {
__pthread_initialize_minimal;
__pthread_clock_gettime; __pthread_clock_settime;
diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index 907411d5bc..ab17bbb6e4 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -279,6 +279,9 @@ __pthread_initialize_minimal_internal (void)
THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
#endif
+ /* Register rseq ABI to the kernel. */
+ (void) __rseq_register_current_thread ();
+
/* Initialize the robust mutex data. */
{
#if __PTHREAD_MUTEX_HAVE_PREV
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index 19efe1e35f..7fb996f12d 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -609,6 +609,9 @@ extern void __shm_directory_freeres (void) attribute_hidden;
extern void __wait_lookup_done (void) attribute_hidden;
+extern int __rseq_register_current_thread (void) attribute_hidden;
+extern int __rseq_unregister_current_thread (void) attribute_hidden;
+
#ifdef SHARED
# define PTHREAD_STATIC_FN_REQUIRE(name)
#else
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index fe75d04113..a5233cdf2f 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -378,6 +378,7 @@ __free_tcb (struct pthread *pd)
START_THREAD_DEFN
{
struct pthread *pd = START_THREAD_SELF;
+ bool has_rseq = false;
#if HP_TIMING_AVAIL
/* Remember the time when the thread was started. */
@@ -396,6 +397,9 @@ START_THREAD_DEFN
if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) == -2))
futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
+ /* Register rseq TLS to the kernel. */
+ has_rseq = !__rseq_register_current_thread ();
+
#ifdef __NR_set_robust_list
# ifndef __ASSUME_SET_ROBUST_LIST
if (__set_robust_list_avail >= 0)
@@ -573,6 +577,10 @@ START_THREAD_DEFN
}
#endif
+ /* Unregister rseq TLS from kernel. */
+ if (has_rseq && __rseq_unregister_current_thread ())
+ abort();
+
advise_stack_range (pd->stackblock, pd->stackblock_size, (uintptr_t) pd,
pd->guardsize);
diff --git a/nptl/rseq.c b/nptl/rseq.c
new file mode 100644
index 0000000000..76e33c8e18
--- /dev/null
+++ b/nptl/rseq.c
@@ -0,0 +1,42 @@
+/* Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Mathieu Desnoyers <[email protected]>, 2018.
+
+ 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
+ <http://www.gnu.org/licenses/>. */
+
+#include "pthreadP.h"
+
+__attribute__((weak))
+__thread volatile uint32_t __rseq_refcount;
+
+#ifdef __NR_rseq
+#include <sysdeps/unix/sysv/linux/rseq-internal.h>
+#else
+#include <sysdeps/nptl/rseq-internal.h>
+#endif /* __NR_rseq. */
+
+int
+attribute_hidden
+__rseq_register_current_thread (void)
+{
+ return sysdep_rseq_register_current_thread ();
+}
+
+int
+attribute_hidden
+__rseq_unregister_current_thread (void)
+{
+ return sysdep_rseq_unregister_current_thread ();
+}
diff --git a/sysdeps/nptl/rseq-internal.h b/sysdeps/nptl/rseq-internal.h
new file mode 100644
index 0000000000..96422ebd57
--- /dev/null
+++ b/sysdeps/nptl/rseq-internal.h
@@ -0,0 +1,34 @@
+/* Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Mathieu Desnoyers <[email protected]>, 2018.
+
+ 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
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef RSEQ_INTERNAL_H
+#define RSEQ_INTERNAL_H
+
+static inline int
+sysdep_rseq_register_current_thread (void)
+{
+ return -1;
+}
+
+static inline int
+sysdep_rseq_unregister_current_thread (void)
+{
+ return -1;
+}
+
+#endif /* rseq-internal.h */
diff --git a/sysdeps/unix/sysv/linux/aarch64/libc.abilist b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
index e66c741d04..36af4d0e94 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libc.abilist
@@ -2138,4 +2138,5 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
diff --git a/sysdeps/unix/sysv/linux/aarch64/libpthread.abilist b/sysdeps/unix/sysv/linux/aarch64/libpthread.abilist
index 9a9e4cee85..d5b010eee1 100644
--- a/sysdeps/unix/sysv/linux/aarch64/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/aarch64/libpthread.abilist
@@ -243,3 +243,4 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
diff --git a/sysdeps/unix/sysv/linux/alpha/libc.abilist b/sysdeps/unix/sysv/linux/alpha/libc.abilist
index 8df162fe99..cdf1d53e35 100644
--- a/sysdeps/unix/sysv/linux/alpha/libc.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libc.abilist
@@ -2033,6 +2033,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/alpha/libpthread.abilist b/sysdeps/unix/sysv/linux/alpha/libpthread.abilist
index b413007ccb..d477af8d10 100644
--- a/sysdeps/unix/sysv/linux/alpha/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/alpha/libpthread.abilist
@@ -227,6 +227,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/arm/libc.abilist b/sysdeps/unix/sysv/linux/arm/libc.abilist
index 43c804f9dc..f11ff5c5cf 100644
--- a/sysdeps/unix/sysv/linux/arm/libc.abilist
+++ b/sysdeps/unix/sysv/linux/arm/libc.abilist
@@ -123,6 +123,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.4 _Exit F
GLIBC_2.4 _IO_2_1_stderr_ D 0xa0
diff --git a/sysdeps/unix/sysv/linux/arm/libpthread.abilist b/sysdeps/unix/sysv/linux/arm/libpthread.abilist
index af82a4c632..b49c38114a 100644
--- a/sysdeps/unix/sysv/linux/arm/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/arm/libpthread.abilist
@@ -27,6 +27,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.4 _IO_flockfile F
GLIBC_2.4 _IO_ftrylockfile F
GLIBC_2.4 _IO_funlockfile F
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index 88b01c2e75..deb2dd860b 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -1880,6 +1880,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/hppa/libpthread.abilist b/sysdeps/unix/sysv/linux/hppa/libpthread.abilist
index bcba07f575..3a307653f4 100644
--- a/sysdeps/unix/sysv/linux/hppa/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libpthread.abilist
@@ -219,6 +219,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/i386/libc.abilist b/sysdeps/unix/sysv/linux/i386/libc.abilist
index 6d02f31612..156235898a 100644
--- a/sysdeps/unix/sysv/linux/i386/libc.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libc.abilist
@@ -2045,6 +2045,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/i386/libpthread.abilist b/sysdeps/unix/sysv/linux/i386/libpthread.abilist
index bece86d246..e95ce92103 100644
--- a/sysdeps/unix/sysv/linux/i386/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/i386/libpthread.abilist
@@ -227,6 +227,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/ia64/libc.abilist b/sysdeps/unix/sysv/linux/ia64/libc.abilist
index 4249712611..39f291f97d 100644
--- a/sysdeps/unix/sysv/linux/ia64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libc.abilist
@@ -1914,6 +1914,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/ia64/libpthread.abilist b/sysdeps/unix/sysv/linux/ia64/libpthread.abilist
index ccc9449826..6e23c0e62d 100644
--- a/sysdeps/unix/sysv/linux/ia64/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/ia64/libpthread.abilist
@@ -219,6 +219,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
index d47b808862..a18501e570 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist
@@ -124,6 +124,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.4 _Exit F
GLIBC_2.4 _IO_2_1_stderr_ D 0x98
diff --git a/sysdeps/unix/sysv/linux/m68k/coldfire/libpthread.abilist b/sysdeps/unix/sysv/linux/m68k/coldfire/libpthread.abilist
index af82a4c632..b49c38114a 100644
--- a/sysdeps/unix/sysv/linux/m68k/coldfire/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/coldfire/libpthread.abilist
@@ -27,6 +27,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.4 _IO_flockfile F
GLIBC_2.4 _IO_ftrylockfile F
GLIBC_2.4 _IO_funlockfile F
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
index d5e38308be..cf0f41ec70 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist
@@ -1989,6 +1989,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/m68k/m680x0/libpthread.abilist b/sysdeps/unix/sysv/linux/m68k/m680x0/libpthread.abilist
index bece86d246..e95ce92103 100644
--- a/sysdeps/unix/sysv/linux/m68k/m680x0/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/m68k/m680x0/libpthread.abilist
@@ -227,6 +227,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/microblaze/libc.abilist b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
index 8596b84399..1405f27555 100644
--- a/sysdeps/unix/sysv/linux/microblaze/libc.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/libc.abilist
@@ -2130,4 +2130,5 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
diff --git a/sysdeps/unix/sysv/linux/microblaze/libpthread.abilist b/sysdeps/unix/sysv/linux/microblaze/libpthread.abilist
index 5067375d23..2a94d9e588 100644
--- a/sysdeps/unix/sysv/linux/microblaze/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/microblaze/libpthread.abilist
@@ -243,3 +243,4 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
index 88e0f896d5..7b0144392f 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist
@@ -1967,6 +1967,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/libpthread.abilist b/sysdeps/unix/sysv/linux/mips/mips32/libpthread.abilist
index 02144967c6..e507b677ee 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/libpthread.abilist
@@ -227,6 +227,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
index aff7462c34..430426e03e 100644
--- a/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist
@@ -1965,6 +1965,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/libpthread.abilist b/sysdeps/unix/sysv/linux/mips/mips64/libpthread.abilist
index 02144967c6..e507b677ee 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/libpthread.abilist
@@ -227,6 +227,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
index 71d82444aa..60915c4d81 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist
@@ -1973,6 +1973,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
index de6c53d293..958488bf19 100644
--- a/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist
@@ -1968,6 +1968,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/nios2/libc.abilist b/sysdeps/unix/sysv/linux/nios2/libc.abilist
index e724bab9fb..9f4be44396 100644
--- a/sysdeps/unix/sysv/linux/nios2/libc.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libc.abilist
@@ -2171,4 +2171,5 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
diff --git a/sysdeps/unix/sysv/linux/nios2/libpthread.abilist b/sysdeps/unix/sysv/linux/nios2/libpthread.abilist
index 78cac2ae27..79fbbec7bb 100644
--- a/sysdeps/unix/sysv/linux/nios2/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/nios2/libpthread.abilist
@@ -241,3 +241,4 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
index e9ecbccb71..758a88cb40 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist
@@ -1993,6 +1993,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/libpthread.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/libpthread.abilist
index 09e8447b06..2def055dec 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/libpthread.abilist
@@ -227,6 +227,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
index da83ea6028..ab8d68446a 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/nofpu/libc.abilist
@@ -1997,6 +1997,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
index 4535b40d15..d9dc159d85 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc-le.abilist
@@ -2228,4 +2228,5 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
index 65725de4f0..cc47390688 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist
@@ -123,6 +123,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 _Exit F
GLIBC_2.3 _IO_2_1_stderr_ D 0xe0
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libpthread-le.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libpthread-le.abilist
index 9a9e4cee85..d5b010eee1 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libpthread-le.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libpthread-le.abilist
@@ -243,3 +243,4 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libpthread.abilist b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libpthread.abilist
index 8300958d47..26a5ced7a2 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/libpthread.abilist
@@ -27,6 +27,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3 _IO_flockfile F
GLIBC_2.3 _IO_ftrylockfile F
GLIBC_2.3 _IO_funlockfile F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
index bbb3c4a8e7..a59d67aca2 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv64/libc.abilist
@@ -2100,4 +2100,5 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
index c370fda73d..9da78d59d2 100644
--- a/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
@@ -235,3 +235,4 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h
new file mode 100644
index 0000000000..2367926def
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/rseq-internal.h
@@ -0,0 +1,71 @@
+/* Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Mathieu Desnoyers <[email protected]>, 2018.
+
+ 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
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef RSEQ_INTERNAL_H
+#define RSEQ_INTERNAL_H
+
+#include <stdint.h>
+#include <linux/rseq.h>
+
+#define RSEQ_SIG 0x53053053
+
+extern __thread volatile struct rseq __rseq_abi
+__attribute__ ((tls_model ("initial-exec")));
+
+extern __thread volatile uint32_t __rseq_refcount
+__attribute__ ((tls_model ("initial-exec")));
+
+static inline int
+sysdep_rseq_register_current_thread (void)
+{
+ int rc, ret = 0;
+ INTERNAL_SYSCALL_DECL (err);
+
+ if (__rseq_abi.cpu_id == RSEQ_CPU_ID_REGISTRATION_FAILED)
+ return -1;
+ rc = INTERNAL_SYSCALL_CALL (rseq, err, &__rseq_abi, sizeof (struct rseq),
+ 0, RSEQ_SIG);
+ if (!rc)
+ {
+ __rseq_refcount = 1;
+ goto end;
+ }
+ if (INTERNAL_SYSCALL_ERRNO (rc, err) != EBUSY)
+ __rseq_abi.cpu_id = RSEQ_CPU_ID_REGISTRATION_FAILED;
+ ret = -1;
+end:
+ return ret;
+}
+
+static inline int
+sysdep_rseq_unregister_current_thread (void)
+{
+ int rc, ret = 0;
+ INTERNAL_SYSCALL_DECL (err);
+
+ __rseq_refcount = 0;
+ rc = INTERNAL_SYSCALL_CALL (rseq, err, &__rseq_abi, sizeof (struct rseq),
+ RSEQ_FLAG_UNREGISTER, RSEQ_SIG);
+ if (!rc)
+ goto end;
+ ret = -1;
+end:
+ return ret;
+}
+
+#endif /* rseq-internal.h */
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
index e85ac2a178..fca7f6de8d 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist
@@ -2002,6 +2002,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/libpthread.abilist b/sysdeps/unix/sysv/linux/s390/s390-32/libpthread.abilist
index d05468f3b2..8876434f46 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/libpthread.abilist
@@ -229,6 +229,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
index d56931022c..74eebccbd0 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist
@@ -1908,6 +1908,7 @@ GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
GLIBC_2.29 __fentry__ F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/libpthread.abilist b/sysdeps/unix/sysv/linux/s390/s390-64/libpthread.abilist
index e8161aa747..2ae3980aba 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/libpthread.abilist
@@ -221,6 +221,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/sh/libc.abilist b/sysdeps/unix/sysv/linux/sh/libc.abilist
index ff939a15c4..e614aa9f0c 100644
--- a/sysdeps/unix/sysv/linux/sh/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sh/libc.abilist
@@ -1884,6 +1884,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/sh/libpthread.abilist b/sysdeps/unix/sysv/linux/sh/libpthread.abilist
index bcba07f575..3a307653f4 100644
--- a/sysdeps/unix/sysv/linux/sh/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/sh/libpthread.abilist
@@ -219,6 +219,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
index 64fa9e10a5..03b0c2dc32 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist
@@ -1996,6 +1996,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/libpthread.abilist b/sysdeps/unix/sysv/linux/sparc/sparc32/libpthread.abilist
index b413007ccb..d477af8d10 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/libpthread.abilist
@@ -227,6 +227,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
index db909d1506..800ea4d98b 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist
@@ -1937,6 +1937,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/libpthread.abilist b/sysdeps/unix/sysv/linux/sparc/sparc64/libpthread.abilist
index ccc9449826..6e23c0e62d 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/libpthread.abilist
@@ -219,6 +219,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
index 3b175f104b..b694817e55 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libc.abilist
@@ -1895,6 +1895,7 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
GLIBC_2.3 __ctype_b_loc F
GLIBC_2.3 __ctype_tolower_loc F
diff --git a/sysdeps/unix/sysv/linux/x86_64/64/libpthread.abilist b/sysdeps/unix/sysv/linux/x86_64/64/libpthread.abilist
index 931c8277a8..889b71fb92 100644
--- a/sysdeps/unix/sysv/linux/x86_64/64/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/64/libpthread.abilist
@@ -219,6 +219,7 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
GLIBC_2.3.2 pthread_cond_broadcast F
GLIBC_2.3.2 pthread_cond_destroy F
GLIBC_2.3.2 pthread_cond_init F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
index 1b57710477..e885d3c6eb 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist
@@ -2146,4 +2146,5 @@ GLIBC_2.28 thrd_current F
GLIBC_2.28 thrd_equal F
GLIBC_2.28 thrd_sleep F
GLIBC_2.28 thrd_yield F
+GLIBC_2.29 __rseq_abi T 0x20
GLIBC_2.29 posix_spawn_file_actions_addchdir_np F
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/libpthread.abilist b/sysdeps/unix/sysv/linux/x86_64/x32/libpthread.abilist
index c09c9b015a..68886246a2 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/libpthread.abilist
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/libpthread.abilist
@@ -243,3 +243,4 @@ GLIBC_2.28 tss_create F
GLIBC_2.28 tss_delete F
GLIBC_2.28 tss_get F
GLIBC_2.28 tss_set F
+GLIBC_2.29 __rseq_refcount T 0x4
--
2.17.1
When available, use the cpu_id field from __rseq_abi on Linux to
implement sched_getcpu(). Fall-back on the vgetcpu vDSO if unavailable.
Benchmarks:
x86-64: Intel E5-2630 [email protected], 16-core, hyperthreading
glibc sched_getcpu(): 13.7 ns (baseline)
glibc sched_getcpu() using rseq: 2.5 ns (speedup: 5.5x)
inline load cpuid from __rseq_abi TLS: 0.8 ns (speedup: 17.1x)
Signed-off-by: Mathieu Desnoyers <[email protected]>
CC: Carlos O'Donell <[email protected]>
CC: Florian Weimer <[email protected]>
CC: Joseph Myers <[email protected]>
CC: Szabolcs Nagy <[email protected]>
CC: Thomas Gleixner <[email protected]>
CC: Ben Maurer <[email protected]>
CC: Peter Zijlstra <[email protected]>
CC: "Paul E. McKenney" <[email protected]>
CC: Boqun Feng <[email protected]>
CC: Will Deacon <[email protected]>
CC: Dave Watson <[email protected]>
CC: Paul Turner <[email protected]>
CC: [email protected]
CC: [email protected]
CC: [email protected]
---
sysdeps/unix/sysv/linux/sched_getcpu.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/sched_getcpu.c b/sysdeps/unix/sysv/linux/sched_getcpu.c
index b69eeda15c..37fda59d36 100644
--- a/sysdeps/unix/sysv/linux/sched_getcpu.c
+++ b/sysdeps/unix/sysv/linux/sched_getcpu.c
@@ -24,8 +24,8 @@
#endif
#include <sysdep-vdso.h>
-int
-sched_getcpu (void)
+static int
+vsyscall_sched_getcpu (void)
{
#ifdef __NR_getcpu
unsigned int cpu;
@@ -37,3 +37,24 @@ sched_getcpu (void)
return -1;
#endif
}
+
+#ifdef __NR_rseq
+#include <linux/rseq.h>
+
+extern __attribute__ ((tls_model ("initial-exec")))
+__thread volatile struct rseq __rseq_abi;
+
+int
+sched_getcpu (void)
+{
+ int cpu_id = __rseq_abi.cpu_id;
+
+ return cpu_id >= 0 ? cpu_id : vsyscall_sched_getcpu ();
+}
+#else
+int
+sched_getcpu (void)
+{
+ return vsyscall_sched_getcpu ();
+}
+#endif
--
2.17.1
* Mathieu Desnoyers:
> diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist b/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
> index c370fda73d..9da78d59d2 100644
> --- a/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
> +++ b/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
> @@ -235,3 +235,4 @@ GLIBC_2.28 tss_create F
> GLIBC_2.28 tss_delete F
> GLIBC_2.28 tss_get F
> GLIBC_2.28 tss_set F
> +GLIBC_2.29 __rseq_refcount T 0x4
This part looks buggy.
It's unclear based on this patch whether you actually want to get rid of
the __rseq_refcount symbol.
Thanks,
Florian
----- On Dec 4, 2018, at 2:44 PM, Florian Weimer [email protected] wrote:
> * Mathieu Desnoyers:
>
>> diff --git a/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
>> b/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
>> index c370fda73d..9da78d59d2 100644
>> --- a/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
>> +++ b/sysdeps/unix/sysv/linux/riscv/rv64/libpthread.abilist
>> @@ -235,3 +235,4 @@ GLIBC_2.28 tss_create F
>> GLIBC_2.28 tss_delete F
>> GLIBC_2.28 tss_get F
>> GLIBC_2.28 tss_set F
>> +GLIBC_2.29 __rseq_refcount T 0x4
>
> This part looks buggy.
>
> It's unclear based on this patch whether you actually want to get rid of
> the __rseq_refcount symbol.
I want to keep the __rseq_refcount symbol so out-of-libc users can
register rseq if they are linked against a pre-2.29 libc.
Why does it look buggy ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
* Mathieu Desnoyers:
> I want to keep the __rseq_refcount symbol so out-of-libc users can
> register rseq if they are linked against a pre-2.29 libc.
Sorry, I was confused.
> diff --git a/csu/Makefile b/csu/Makefile
> index 88fc77662e..81d471587f 100644
> --- a/csu/Makefile
> +++ b/csu/Makefile
> @@ -28,7 +28,7 @@ include ../Makeconfig
>
> routines = init-first libc-start $(libc-init) sysdep version check_fds \
> libc-tls elf-init dso_handle
> -aux = errno
> +aux = errno rseq
> elide-routines.os = libc-tls
> static-only-routines = elf-init
> csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
Do we plan to add Hurd support for this?
> diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h
> new file mode 100644
> index 0000000000..2367926def
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/rseq-internal.h
> +#define RSEQ_SIG 0x53053053
What's this? This needs a comment.
> +extern __thread volatile struct rseq __rseq_abi
> +__attribute__ ((tls_model ("initial-exec")));
> +
> +extern __thread volatile uint32_t __rseq_refcount
> +__attribute__ ((tls_model ("initial-exec")));
The volatile qualifier needs justification in a comment. (Usually,
volatile is wrong. and it is difficult to get rid of it.)
We need to document these public symbols somewhere. There should be an
installed header file.
> diff --git a/nptl/Versions b/nptl/Versions
> index e7f691da7a..f7890f73fc 100644
> --- a/nptl/Versions
> +++ b/nptl/Versions
> @@ -277,6 +277,10 @@ libpthread {
> cnd_timedwait; cnd_wait; tss_create; tss_delete; tss_get; tss_set;
> }
>
> + GLIBC_2.29 {
> + __rseq_refcount;
> + }
Why put this into libpthread, and __rseq_abi into libc?
What, exactly, is the benefit of having __rseq_refcount defined by
glibc? Have you actually got this working? If an rseq library is
linked against glibc 2.29, it will reference the GLIBC_2.29 symbol
version, so it cannot be loaded by older glibcs. In this case,
__rseq_refcount is not needed.
If you build against pre-2.29, then the __rseq_refcount symbol will be
unversioned. But then you don't need it glibc, either.
So it seems to me that the addition to glibc is useless in both
scenarios. Am I missing something?
By the way, you could avoid the need for unregistration if you allocated
the rseq areas persistently, index by TID. They are quite small, so
with the typical PID range, maybe the wasted memory due to changing TIDs
would be acceptable?
I guess things would be so much easier if the kernel simply provided a
means to obtain the address of a previously registered rseq area.
Thanks,
Florian
----- On Dec 11, 2018, at 2:40 AM, Florian Weimer [email protected] wrote:
> * Mathieu Desnoyers:
>
>> I want to keep the __rseq_refcount symbol so out-of-libc users can
>> register rseq if they are linked against a pre-2.29 libc.
>
> Sorry, I was confused.
Hi Florian,
Thanks for your questions below. Sorry for my delayed answer, I've
been preempted by vacation time. See more below,
>
>> diff --git a/csu/Makefile b/csu/Makefile
>> index 88fc77662e..81d471587f 100644
>> --- a/csu/Makefile
>> +++ b/csu/Makefile
>> @@ -28,7 +28,7 @@ include ../Makeconfig
>>
>> routines = init-first libc-start $(libc-init) sysdep version check_fds \
>> libc-tls elf-init dso_handle
>> -aux = errno
>> +aux = errno rseq
>> elide-routines.os = libc-tls
>> static-only-routines = elf-init
>> csu-dummies = $(filter-out $(start-installed-name),crt1.o Mcrt1.o)
>
> Do we plan to add Hurd support for this?
No.
A logical path where we could move rseq.c is under sysdeps/unix/sysv/linux/rseq.c.
This would allow the __rseq_abi symbol to be used from anywhere in glibc.
>
>> diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h
>> b/sysdeps/unix/sysv/linux/rseq-internal.h
>> new file mode 100644
>> index 0000000000..2367926def
>> --- /dev/null
>> +++ b/sysdeps/unix/sysv/linux/rseq-internal.h
>
>> +#define RSEQ_SIG 0x53053053
>
> What's this? This needs a comment.
I will move it to an installed header (sysdeps/unix/sysv/linux/sys/rseq.h)
with the following comment:
/* Signature required before each abort handler code. */
#define RSEQ_SIG 0x53053053
>
>> +extern __thread volatile struct rseq __rseq_abi
>> +__attribute__ ((tls_model ("initial-exec")));
>> +
>> +extern __thread volatile uint32_t __rseq_refcount
>> +__attribute__ ((tls_model ("initial-exec")));
>
> The volatile qualifier needs justification in a comment. (Usually,
> volatile is wrong. and it is difficult to get rid of it.)
>
> We need to document these public symbols somewhere. There should be an
> installed header file.
Moving to sysdeps/unix/sysv/linux/sys/rseq.h with the following comments:
/* volatile because fields can be read/updated by the kernel. */
extern __thread volatile struct rseq __rseq_abi
__attribute__ ((tls_model ("initial-exec")));
/* volatile because refcount can be read/updated by signal handlers. */
extern __thread volatile uint32_t __rseq_refcount
__attribute__ ((tls_model ("initial-exec")));
>
>> diff --git a/nptl/Versions b/nptl/Versions
>> index e7f691da7a..f7890f73fc 100644
>> --- a/nptl/Versions
>> +++ b/nptl/Versions
>> @@ -277,6 +277,10 @@ libpthread {
>> cnd_timedwait; cnd_wait; tss_create; tss_delete; tss_get; tss_set;
>> }
>>
>> + GLIBC_2.29 {
>> + __rseq_refcount;
>> + }
>
> Why put this into libpthread, and __rseq_abi into libc?
The __rseq_abi symbol should be available to the glibc memory allocator.
I plan to move the __rseq_abi to sysdeps/unix/sysv/linux/Versions instead
so it becomes Linux-specific.
The __rseq_refcount symbol only needs to be made available to applications
and libraries linking against libpthread, because only libpthread actually
handles the rseq registration/unregistration at thread start/exit and
library initialization.
However, considering that we want this to be Linux-specific as well,
I could move it to sysdeps/unix/sysv/linux/Versions too.
Then it would make sense to move the __rseq_refcount symbol defined in
nptl/rseq.c to sysdeps/unix/sysv/linux/rseq.c as well and group
everything together.
Therefore, both symbols will end up in sysdeps/unix/sysv/linux/Versions.
>
> What, exactly, is the benefit of having __rseq_refcount defined by
> glibc? Have you actually got this working? If an rseq library is
> linked against glibc 2.29, it will reference the GLIBC_2.29 symbol
> version, so it cannot be loaded by older glibcs. In this case,
> __rseq_refcount is not needed.
>
> If you build against pre-2.29, then the __rseq_refcount symbol will be
> unversioned. But then you don't need it glibc, either.
>
> So it seems to me that the addition to glibc is useless in both
> scenarios. Am I missing something?
Here is the scenario where it becomes useful:
librseq is built against a pre-2.29 glibc. So the __rseq_refcount symbol
it emits is unversioned. Application is build against 2.29 glibc.
Application links both against librseq (itself built against pre-2.29 glibc)
and glibc (2.29).
In that scenario, librseq and glibc rely on a unique __rseq_refcount TLS
variable per process ensure that they don't register rseq twice for each thread.
>
> By the way, you could avoid the need for unregistration if you allocated
> the rseq areas persistently, index by TID. They are quite small, so
> with the typical PID range, maybe the wasted memory due to changing TIDs
> would be acceptable?
Would we be able to access those __rseq_abi as normal TLS IE model variables ?
The overhead of indexing an array matters for a fast-path.
>
> I guess things would be so much easier if the kernel simply provided a
> means to obtain the address of a previously registered rseq area.
Even if the kernel did provide this (which is not part of the syscall ABI anyway),
I suspect we would need extra code on the fast-path to access the __rseq_abi
TLS, which I would very much like to avoid. But perhaps there are ways to do
this without extra overhead that are beyond my understanding of glibc handling
of TLS models.
I will soon post an updated patch set taking care of your comments.
Thanks!
Mathieu
>
> Thanks,
> Florian
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
----- On Jan 10, 2019, at 12:31 PM, Mathieu Desnoyers [email protected] wrote:
> ----- On Dec 11, 2018, at 2:40 AM, Florian Weimer [email protected] wrote:
[...]
>>
>>> diff --git a/nptl/Versions b/nptl/Versions
>>> index e7f691da7a..f7890f73fc 100644
>>> --- a/nptl/Versions
>>> +++ b/nptl/Versions
>>> @@ -277,6 +277,10 @@ libpthread {
>>> cnd_timedwait; cnd_wait; tss_create; tss_delete; tss_get; tss_set;
>>> }
>>>
>>> + GLIBC_2.29 {
>>> + __rseq_refcount;
>>> + }
>>
>> Why put this into libpthread, and __rseq_abi into libc?
>
> The __rseq_abi symbol should be available to the glibc memory allocator.
> I plan to move the __rseq_abi to sysdeps/unix/sysv/linux/Versions instead
> so it becomes Linux-specific.
>
> The __rseq_refcount symbol only needs to be made available to applications
> and libraries linking against libpthread, because only libpthread actually
> handles the rseq registration/unregistration at thread start/exit and
> library initialization.
>
> However, considering that we want this to be Linux-specific as well,
> I could move it to sysdeps/unix/sysv/linux/Versions too.
>
> Then it would make sense to move the __rseq_refcount symbol defined in
> nptl/rseq.c to sysdeps/unix/sysv/linux/rseq.c as well and group
> everything together.
>
> Therefore, both symbols will end up in sysdeps/unix/sysv/linux/Versions.
Now that I think about it, it's important to move the rseq registration
done at nptl init (in my current code) to some lower-level csu initialiation,
so applications that happen _not_ to link against libpthread also get
registered rseq for the main thread.
Does it make sense ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
* Mathieu Desnoyers:
> Therefore, both symbols will end up in
> sysdeps/unix/sysv/linux/Versions.
I'm not sure what you mean by that. The physical location in the
directory tree has little effect on which shared object the symbol is
placed in; that will need other changes.
>> By the way, you could avoid the need for unregistration if you allocated
>> the rseq areas persistently, index by TID. They are quite small, so
>> with the typical PID range, maybe the wasted memory due to changing TIDs
>> would be acceptable?
>
> Would we be able to access those __rseq_abi as normal TLS IE model
> variables ? The overhead of indexing an array matters for a
> fast-path.
No, that wouldn't be possible in this case. You would need another
indirection.
Thanks,
Florian
* Mathieu Desnoyers:
> Now that I think about it, it's important to move the rseq registration
> done at nptl init (in my current code) to some lower-level csu initialiation,
> so applications that happen _not_ to link against libpthread also get
> registered rseq for the main thread.
Yes. In general, we want to avoid to force libraries which do not
create threads to link against libpthread, and try to provide interfaces
which are required for synchronization within libc.
Thanks,
Florian
----- On Jan 14, 2019, at 10:55 AM, Florian Weimer [email protected] wrote:
> * Mathieu Desnoyers:
>
>> Therefore, both symbols will end up in
>> sysdeps/unix/sysv/linux/Versions.
>
> I'm not sure what you mean by that. The physical location in the
> directory tree has little effect on which shared object the symbol is
> placed in; that will need other changes.
I'm currently moving the symbol definitions to csu/rseq-sym.c. On Linux,
its content is overridden by a new sysdeps/unix/sysv/linux/rseq-sym.c
which contains both __rseq_abi and __rseq_refcount symbols. On other
platforms, it is a stub file.
>>> By the way, you could avoid the need for unregistration if you allocated
>>> the rseq areas persistently, index by TID. They are quite small, so
>>> with the typical PID range, maybe the wasted memory due to changing TIDs
>>> would be acceptable?
>>
>> Would we be able to access those __rseq_abi as normal TLS IE model
>> variables ? The overhead of indexing an array matters for a
>> fast-path.
>
> No, that wouldn't be possible in this case. You would need another
> indirection.
Thanks for the clarification!
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
* Mathieu Desnoyers:
> ----- On Jan 14, 2019, at 10:55 AM, Florian Weimer [email protected] wrote:
>
>> * Mathieu Desnoyers:
>>
>>> Therefore, both symbols will end up in
>>> sysdeps/unix/sysv/linux/Versions.
>>
>> I'm not sure what you mean by that. The physical location in the
>> directory tree has little effect on which shared object the symbol is
>> placed in; that will need other changes.
>
> I'm currently moving the symbol definitions to csu/rseq-sym.c. On Linux,
> its content is overridden by a new sysdeps/unix/sysv/linux/rseq-sym.c
> which contains both __rseq_abi and __rseq_refcount symbols. On other
> platforms, it is a stub file.
You don't need a stub file if you use the “ifeq ($(subdir),csu)”
construct.
The other question is whether this belongs into the csu subdirectory.
Since TLS is not available in ld.so, the initialization would have to
happen rather late, after relocation, but before ELF constructors are
run.
(A side effect is that the rseq area would not be usable from IFUNC
resolvers.)
Thanks,
Florian
----- On Jan 14, 2019, at 2:37 PM, Florian Weimer [email protected] wrote:
> * Mathieu Desnoyers:
>
>> ----- On Jan 14, 2019, at 10:55 AM, Florian Weimer [email protected] wrote:
>>
>>> * Mathieu Desnoyers:
>>>
>>>> Therefore, both symbols will end up in
>>>> sysdeps/unix/sysv/linux/Versions.
>>>
>>> I'm not sure what you mean by that. The physical location in the
>>> directory tree has little effect on which shared object the symbol is
>>> placed in; that will need other changes.
>>
>> I'm currently moving the symbol definitions to csu/rseq-sym.c. On Linux,
>> its content is overridden by a new sysdeps/unix/sysv/linux/rseq-sym.c
>> which contains both __rseq_abi and __rseq_refcount symbols. On other
>> platforms, it is a stub file.
>
> You don't need a stub file if you use the “ifeq ($(subdir),csu)”
> construct.
OK
>
> The other question is whether this belongs into the csu subdirectory.
> Since TLS is not available in ld.so, the initialization would have to
> happen rather late, after relocation, but before ELF constructors are
> run.
>
> (A side effect is that the rseq area would not be usable from IFUNC
> resolvers.)
Do you have a specific directory location in mind where we should put
the built object ? e.g. "ifeq ($(subdir),posix)" or
"ifeq ($(subdir),misc)" ?
Moreover, from where should we call the rseq initialization ? I'm having
trouble with invalid system calls parameters if I place it in
LIBC_START_MAIN() just before or after the call to __pthread_initialize_minimal.
I get what appears to be invalid parameters to sys_rseq, possibly due to
stack corruption (?). I'm investigating at the moment. But if you prefer
we call the rseq init from elsewhere, please let me know.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com