[PATCH v2 1/7] y2038: linux: Provide __clock_adjtime64 implementation
Lukasz Majewski
lukma@denx.de
Fri May 8 14:56:34 GMT 2020
This patch replaces auto generated wrapper (as described in
sysdeps/unix/sysv/linux/syscalls.list) for clock_adjtime with one which adds
extra support for reading 64 bit time values on machines with __TIMESIZE != 64.
To achieve this goal new __clock_adjtime64 explicit 64 bit function for
adjusting Linux clock has been added.
Moreover, a 32 bit version - __clock_adjtime has been refactored to internally
use __clock_adjtime64.
The __clock_adjtime is now supposed to be used on systems still supporting 32
bit time (__TIMESIZE != 64) - hence the necessary conversions between 64 bit
struct __timespec64 and struct timespec.
The new __clock_adjtime64 syscall available from Linux 5.1+ has been used, when
applicable.
Up till v5.4 in the Linux kernel there was a bug preventing this call from
obtaining correct struct's timex time.tv_sec time after time_t overflow
(i.e. not being Y2038 safe).
Build tests:
- ./src/scripts/build-many-glibcs.py glibcs
Run-time tests:
- Run specific tests on ARM/x86 32bit systems (qemu):
https://github.com/lmajewski/meta-y2038 and run tests:
https://github.com/lmajewski/y2038-tests/commits/master
Linux kernel, headers and minimal kernel version for glibc build test matrix:
- Linux v5.1 (with clock_adjtime64) and glibc build with v5.1 as
minimal kernel version (--enable-kernel="5.1.0")
The __ASSUME_TIME64_SYSCALLS flag defined.
- Linux v5.1 and default minimal kernel version
The __ASSUME_TIME64_SYSCALLS not defined, but kernel supports clock_adjtime64
syscall.
- Linux v4.19 (no clock_adjtime64 support) with default minimal kernel version
for contemporary glibc (3.2.0)
This kernel doesn't support clock_adjtime64 syscall, so the fallback to
clock_adjtime is tested.
Above tests were performed with Y2038 redirection applied as well as without
(so the __TIMESIZE != 64 execution path is checked as well).
No regressions were observed.
Changes for v2:
- Fix wrong indentation
- Remove the check for (ret >= TIME_OK && ret <= TIME_ERROR) in the
clock_adjtime64 call - just check if syscall returned ENOSYS
- Add 64 bit time overflow for ADJ_SETOFFSET set in modes
---
sysdeps/unix/sysv/linux/Makefile | 2 +-
sysdeps/unix/sysv/linux/clock_adjtime.c | 71 +++++++++++++++++++++
sysdeps/unix/sysv/linux/include/sys/timex.h | 3 +
sysdeps/unix/sysv/linux/syscalls.list | 1 -
4 files changed, 75 insertions(+), 2 deletions(-)
create mode 100644 sysdeps/unix/sysv/linux/clock_adjtime.c
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 0326f92c40..2f2fd5d4d0 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -60,7 +60,7 @@ sysdep_routines += adjtimex clone umount umount2 readahead sysctl \
personality epoll_wait tee vmsplice splice \
open_by_handle_at mlock2 pkey_mprotect pkey_set pkey_get \
timerfd_gettime timerfd_settime prctl \
- process_vm_readv process_vm_writev
+ process_vm_readv process_vm_writev clock_adjtime
CFLAGS-gethostid.c = -fexceptions
CFLAGS-tee.c = -fexceptions -fasynchronous-unwind-tables
diff --git a/sysdeps/unix/sysv/linux/clock_adjtime.c b/sysdeps/unix/sysv/linux/clock_adjtime.c
new file mode 100644
index 0000000000..5c02031bb5
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/clock_adjtime.c
@@ -0,0 +1,71 @@
+/* clock_adjtime -- tune kernel clock
+ Copyright (C) 2020 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; see the file COPYING.LIB. If
+ not, see <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <time.h>
+#include <sysdep.h>
+#include <sys/timex.h>
+#include <kernel-features.h>
+
+int
+__clock_adjtime64 (const clockid_t clock_id, struct __timex64 *tx64)
+{
+#ifdef __ASSUME_TIME64_SYSCALLS
+# ifndef __NR_clock_adjtime64
+# define __NR_clock_adjtime64 __NR_clock_adjtime
+# endif
+ return INLINE_SYSCALL_CALL (clock_adjtime64, clock_id, tx64);
+#else
+ int ret = INLINE_SYSCALL_CALL (clock_adjtime64, clock_id, tx64);
+ if (errno != ENOSYS)
+ return ret;
+
+ if (tx64->modes & ADJ_SETOFFSET
+ && ! in_time_t_range (tx64->time.tv_sec))
+ {
+ __set_errno (EOVERFLOW);
+ return -1;
+ }
+
+ struct timex tx32 = valid_timex64_to_timex (*tx64);
+ int retval = INLINE_SYSCALL_CALL (clock_adjtime, clock_id, &tx32);
+ *tx64 = valid_timex_to_timex64 (tx32);
+
+ return retval;
+#endif
+}
+
+#if __TIMESIZE != 64
+libc_hidden_def (__clock_adjtime64)
+
+int
+__clock_adjtime (const clockid_t clock_id, struct timex *tx)
+{
+ struct __timex64 tx64;
+ int retval;
+
+ tx64 = valid_timex_to_timex64 (*tx);
+ retval = __clock_adjtime64 (clock_id, &tx64);
+ *tx = valid_timex64_to_timex (tx64);
+
+ return retval;
+}
+#endif
+libc_hidden_def (__clock_adjtime);
+strong_alias (__clock_adjtime, clock_adjtime)
diff --git a/sysdeps/unix/sysv/linux/include/sys/timex.h b/sysdeps/unix/sysv/linux/include/sys/timex.h
index 3efe7cd306..2848c5cf76 100644
--- a/sysdeps/unix/sysv/linux/include/sys/timex.h
+++ b/sysdeps/unix/sysv/linux/include/sys/timex.h
@@ -30,6 +30,7 @@ libc_hidden_proto (__adjtimex)
/* Local definition of 64 bit time supporting timex struct */
# if __TIMESIZE == 64
# define __timex64 timex
+# define __clock_adjtime64 __clock_adjtime
# else
struct __timex64
@@ -71,6 +72,8 @@ struct __timex64
int :32;
int :32;
};
+extern int __clock_adjtime64 (const clockid_t clock_id, struct __timex64 *tx64);
+libc_hidden_proto (__clock_adjtime64);
# endif
/* Convert a known valid struct timex into a struct __timex64. */
diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index 1d8893d1b8..01ec2bfa95 100644
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -4,7 +4,6 @@ alarm - alarm i:i alarm
bdflush EXTRA bdflush i:ii __compat_bdflush bdflush@GLIBC_2.0:GLIBC_2.23
capget EXTRA capget i:pp capget
capset EXTRA capset i:pp capset
-clock_adjtime EXTRA clock_adjtime i:ip __clock_adjtime clock_adjtime
create_module EXTRA create_module 3 __compat_create_module create_module@GLIBC_2.0:GLIBC_2.23
delete_module EXTRA delete_module 3 delete_module
epoll_create EXTRA epoll_create i:i epoll_create
--
2.20.1
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