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* [glibc] y2038: linux: Provide __time64 implementation
@ 2020-10-19 14:44 Lukasz Majewski
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From: Lukasz Majewski @ 2020-10-19 14:44 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=75c4044b9a49faaeec245cc3a79a390dde7c804e
commit 75c4044b9a49faaeec245cc3a79a390dde7c804e
Author: Lukasz Majewski <lukma@denx.de>
Date: Wed Oct 14 13:45:43 2020 +0200
y2038: linux: Provide __time64 implementation
In the glibc the time function can use vDSO (on power and x86 the
USE_IFUNC_TIME is defined), time syscall or 'default' time() from
./time/time.c (as a fallback).
In this patch the last function (time) has been refactored and moved
to ./sysdeps/unix/sysv/linux/time.c to be Linux specific.
The new __time64 explicit 64 bit function for providing 64 bit value of
seconds after epoch (by internally calling __clock_gettime64) has been
introduced.
Moreover, a 32 bit version - __time has been refactored to internally
use __time64.
The __time is now supposed to be used on systems still supporting 32 bit
time (__TIMESIZE != 64) - hence the necessary check for time_t potential
overflow.
The iFUNC vDSO direct call optimization has been removed from both i686 and
powerpc32 (USE_IFUNC_TIME is not defined for those architectures
anymore). The Linux kernel does not provide a y2038 safe implementation of
time neither it plans to provide it in the future, __clock_gettime64
should be used instead. Keeping support for this optimization would require
to handle another build permutation (!__ASSUME_TIME64_SYSCALLS &&
USE_IFUNC_TIME which adds more complexity and has limited use (since the
idea is to eventually have a y2038 safe glibc build).
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
Above tests were performed with Y2038 redirection applied as well as
without to test proper usage of both __time64 and __time.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diff:
---
include/time.h | 7 +++++++
sysdeps/unix/sysv/linux/powerpc/time.c | 4 +++-
sysdeps/unix/sysv/linux/time.c | 38 +++++++++++++++++++++++++++++++++-
sysdeps/unix/sysv/linux/x86/time.c | 4 +++-
4 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/include/time.h b/include/time.h
index edf6cdf829..caf2af5e74 100644
--- a/include/time.h
+++ b/include/time.h
@@ -317,6 +317,13 @@ extern int __timespec_get64 (struct __timespec64 *ts, int base);
libc_hidden_proto (__timespec_get64)
#endif
+#if __TIMESIZE == 64
+# define __time64 __time
+#else
+extern __time64_t __time64 (__time64_t *timer);
+libc_hidden_proto (__time64)
+#endif
+
/* Use in the clock_* functions. Size of the field representing the
actual clock ID. */
#define CLOCK_IDFIELD_SIZE 3
diff --git a/sysdeps/unix/sysv/linux/powerpc/time.c b/sysdeps/unix/sysv/linux/powerpc/time.c
index d10f449c5c..4fd5e138a3 100644
--- a/sysdeps/unix/sysv/linux/powerpc/time.c
+++ b/sysdeps/unix/sysv/linux/powerpc/time.c
@@ -16,5 +16,7 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#define USE_IFUNC_TIME
+#ifdef __powerpc64__
+# define USE_IFUNC_TIME
+#endif
#include <sysdeps/unix/sysv/linux/time.c>
diff --git a/sysdeps/unix/sysv/linux/time.c b/sysdeps/unix/sysv/linux/time.c
index 9d8e573c0a..df5d4ca0fb 100644
--- a/sysdeps/unix/sysv/linux/time.c
+++ b/sysdeps/unix/sysv/linux/time.c
@@ -47,5 +47,41 @@ time (time_t *t)
}
# endif /* !SHARED */
#else /* USE_IFUNC_TIME */
-# include <time/time.c>
+# include <time.h>
+# include <time-clockid.h>
+# include <errno.h>
+
+/* Return the time now, and store it in *TIMER if not NULL. */
+
+__time64_t
+__time64 (__time64_t *timer)
+{
+ struct __timespec64 ts;
+ __clock_gettime64 (TIME_CLOCK_GETTIME_CLOCKID, &ts);
+
+ if (timer != NULL)
+ *timer = ts.tv_sec;
+ return ts.tv_sec;
+}
+
+# if __TIMESIZE != 64
+libc_hidden_def (__time64)
+
+time_t
+__time (time_t *timer)
+{
+ __time64_t t = __time64 (NULL);
+
+ if (! in_time_t_range (t))
+ {
+ __set_errno (EOVERFLOW);
+ return -1;
+ }
+
+ if (timer != NULL)
+ *timer = t;
+ return t;
+}
+# endif
+weak_alias (__time, time)
#endif
diff --git a/sysdeps/unix/sysv/linux/x86/time.c b/sysdeps/unix/sysv/linux/x86/time.c
index 1d158e443c..ed2c5f5dbb 100644
--- a/sysdeps/unix/sysv/linux/x86/time.c
+++ b/sysdeps/unix/sysv/linux/x86/time.c
@@ -16,5 +16,7 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#define USE_IFUNC_TIME
+#ifdef __x86_64__
+# define USE_IFUNC_TIME
+#endif
#include <sysdeps/unix/sysv/linux/time.c>
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