[v2,2/2] sysdeps/clock_gettime: Use clock_gettime64 if avaliable
Commit Message
With the clock_gettime64 call we prefer to use vDSO. There is no call
to clock_gettime64 on glibc with older headers and kernel 5.1+ if it
doesn't support vDSO.
---
This was patch was runtime tested with RV32 and RV64
It was build tested using the ./scripts/build-many-glibcs.py script.
I also ran:
$ make ; make install ; make check
tests on native ARM (32-bit) with the following three confiugrations:
- 4.19 Kernel and 4.19 Headers
- 5.2 Kernel and 4.19 Headers
- 5.2 Kernel and 5.2 Headers
and didn't see any regressions
v2:
- Add commit message
- Change ret_64 to int
include/time.h | 3 ++
sysdeps/unix/sysv/linux/clock_gettime.c | 50 ++++++++++++++++++++++++-
2 files changed, 52 insertions(+), 1 deletion(-)
Comments
On 09/11/2019 23:56, Alistair Francis wrote:
> With the clock_gettime64 call we prefer to use vDSO. There is no call
> to clock_gettime64 on glibc with older headers and kernel 5.1+ if it
> doesn't support vDSO.
> ---
> This was patch was runtime tested with RV32 and RV64
> It was build tested using the ./scripts/build-many-glibcs.py script.
>
> I also ran:
> $ make ; make install ; make check
> tests on native ARM (32-bit) with the following three confiugrations:
> - 4.19 Kernel and 4.19 Headers
> - 5.2 Kernel and 4.19 Headers
> - 5.2 Kernel and 5.2 Headers
> and didn't see any regressions
>
> v2:
> - Add commit message
> - Change ret_64 to int
>
> include/time.h | 3 ++
> sysdeps/unix/sysv/linux/clock_gettime.c | 50 ++++++++++++++++++++++++-
> 2 files changed, 52 insertions(+), 1 deletion(-)
>
> diff --git a/include/time.h b/include/time.h
> index d7800eb30f8..c19c73ae09f 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -211,11 +211,14 @@ extern double __difftime (time_t time1, time_t time0);
>
> #if __TIMESIZE == 64
> # define __clock_nanosleep_time64 __clock_nanosleep
> +# define __clock_gettime64 __clock_gettime
> #else
> extern int __clock_nanosleep_time64 (clockid_t clock_id,
> int flags, const struct __timespec64 *req,
> struct __timespec64 *rem);
> libc_hidden_proto (__clock_nanosleep_time64)
> +extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
> +libc_hidden_proto (__clock_gettime64)
> #endif
>
> /* Use in the clock_* functions. Size of the field representing the
> diff --git a/sysdeps/unix/sysv/linux/clock_gettime.c b/sysdeps/unix/sysv/linux/clock_gettime.c
> index ca40983f6ca..e7af9902f3e 100644
> --- a/sysdeps/unix/sysv/linux/clock_gettime.c
> +++ b/sysdeps/unix/sysv/linux/clock_gettime.c
> @@ -17,6 +17,7 @@
> <https://www.gnu.org/licenses/>. */
>
> #include <sysdep.h>
> +#include <kernel-features.h>
> #include <errno.h>
> #include <time.h>
> #include "kernel-posix-cpu-timers.h"
It requires to define HAVE_SYSCALL if HAVE_CLOCK_GETTIME64_VSYSCALL is also
defined, otherwise architectures that define __ASSUME_TIME64_SYSCALLS and
HAVE_CLOCK_GETTIME64_VSYSCALL will not use the vdso.
> @@ -30,10 +31,57 @@
>
> /* Get current value of CLOCK and store it in TP. */
> int
> +__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
> +{
> +#ifdef __ASSUME_TIME64_SYSCALLS
> +# ifndef __NR_clock_gettime64
> +# define __NR_clock_gettime64 __NR_clock_gettime
> +# define __vdso_clock_gettime64 __vdso_clock_gettime
> +# endif
> + return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
Right, so it would call either __vdso_clock_gettime/__NR_clock_gettime or
__vdso_clock_gettime64/__NR_clock_gettime64.
> +#else
> +# if defined __NR_clock_gettime64 && defined HAVE_CLOCK_GETTIME64_VSYSCALL
I think we can assume that if the ABI provides the time64 vDSO symbol
it also provides the syscall (__NR_clock_gettime64). So we can just
check if HAVE_CLOCK_GETTIME64_VSYSCALL is defined. Something like:
#ifdef __ASSUME_TIME64_SYSCALLS
# ifndef __NR_clock_gettime64
# define __NR_clock_gettime64 __NR_clock_gettime
# define __vdso_clock_gettime64 __vdso_clock_gettime
# endif
return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
#else
# if defined HAVE_CLOCK_GETTIME64_VSYSCALL
int ret64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
if (ret64 == 0 || errno != ENOSYS)
return ret64;
# endif
struct timespec tp32;
int ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
if (ret == 0)
*tp = valid_timespec_to_timespec64 (tp32);
return ret;
#endif
> + int ret_64;
> + ret_64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> +
> + if (ret_64 == 0 || errno != ENOSYS)
> + return ret_64;
> +# endif /* __NR_clock_gettime64 && HAVE_CLOCK_GETTIME64_VSYSCALL */
> + int ret;
> + struct timespec tp32;
> +
> + ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
> +
> + if (ret == 0)
> + *tp = valid_timespec_to_timespec64 (tp32);
> +
> + return ret;
> +#endif /* __ASSUME_TIME64_SYSCALLS */
Ok.
> +}
> +
> +#if __TIMESIZE != 64
> +int
> __clock_gettime (clockid_t clock_id, struct timespec *tp)
> {
> - return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
> + int ret;
> + struct __timespec64 tp64;
> +
> + ret = __clock_gettime64 (clock_id, &tp64);
> +
> + if (ret == 0)
> + {
> + if (! in_time_t_range (tp64.tv_sec))
> + {
> + __set_errno (EOVERFLOW);
> + return -1;
> + }
> +
> + *tp = valid_timespec64_to_timespec (tp64);
> + }
> +
> + return ret;
> }
> +#endif
> libc_hidden_def (__clock_gettime)
>
> versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);
Ok.
On Thu, Nov 21, 2019 at 9:47 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 09/11/2019 23:56, Alistair Francis wrote:
> > With the clock_gettime64 call we prefer to use vDSO. There is no call
> > to clock_gettime64 on glibc with older headers and kernel 5.1+ if it
> > doesn't support vDSO.
> > ---
> > This was patch was runtime tested with RV32 and RV64
> > It was build tested using the ./scripts/build-many-glibcs.py script.
> >
> > I also ran:
> > $ make ; make install ; make check
> > tests on native ARM (32-bit) with the following three confiugrations:
> > - 4.19 Kernel and 4.19 Headers
> > - 5.2 Kernel and 4.19 Headers
> > - 5.2 Kernel and 5.2 Headers
> > and didn't see any regressions
> >
> > v2:
> > - Add commit message
> > - Change ret_64 to int
> >
> > include/time.h | 3 ++
> > sysdeps/unix/sysv/linux/clock_gettime.c | 50 ++++++++++++++++++++++++-
> > 2 files changed, 52 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/time.h b/include/time.h
> > index d7800eb30f8..c19c73ae09f 100644
> > --- a/include/time.h
> > +++ b/include/time.h
> > @@ -211,11 +211,14 @@ extern double __difftime (time_t time1, time_t time0);
> >
> > #if __TIMESIZE == 64
> > # define __clock_nanosleep_time64 __clock_nanosleep
> > +# define __clock_gettime64 __clock_gettime
> > #else
> > extern int __clock_nanosleep_time64 (clockid_t clock_id,
> > int flags, const struct __timespec64 *req,
> > struct __timespec64 *rem);
> > libc_hidden_proto (__clock_nanosleep_time64)
> > +extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
> > +libc_hidden_proto (__clock_gettime64)
> > #endif
> >
> > /* Use in the clock_* functions. Size of the field representing the
> > diff --git a/sysdeps/unix/sysv/linux/clock_gettime.c b/sysdeps/unix/sysv/linux/clock_gettime.c
> > index ca40983f6ca..e7af9902f3e 100644
> > --- a/sysdeps/unix/sysv/linux/clock_gettime.c
> > +++ b/sysdeps/unix/sysv/linux/clock_gettime.c
> > @@ -17,6 +17,7 @@
> > <https://www.gnu.org/licenses/>. */
> >
> > #include <sysdep.h>
> > +#include <kernel-features.h>
> > #include <errno.h>
> > #include <time.h>
> > #include "kernel-posix-cpu-timers.h"
>
> It requires to define HAVE_SYSCALL if HAVE_CLOCK_GETTIME64_VSYSCALL is also
> defined, otherwise architectures that define __ASSUME_TIME64_SYSCALLS and
> HAVE_CLOCK_GETTIME64_VSYSCALL will not use the vdso.
>
> > @@ -30,10 +31,57 @@
> >
> > /* Get current value of CLOCK and store it in TP. */
> > int
> > +__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
> > +{
> > +#ifdef __ASSUME_TIME64_SYSCALLS
> > +# ifndef __NR_clock_gettime64
> > +# define __NR_clock_gettime64 __NR_clock_gettime
> > +# define __vdso_clock_gettime64 __vdso_clock_gettime
> > +# endif
> > + return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
>
> Right, so it would call either __vdso_clock_gettime/__NR_clock_gettime or
> __vdso_clock_gettime64/__NR_clock_gettime64.
>
> > +#else
> > +# if defined __NR_clock_gettime64 && defined HAVE_CLOCK_GETTIME64_VSYSCALL
>
> I think we can assume that if the ABI provides the time64 vDSO symbol
> it also provides the syscall (__NR_clock_gettime64). So we can just
> check if HAVE_CLOCK_GETTIME64_VSYSCALL is defined. Something like:
>
> #ifdef __ASSUME_TIME64_SYSCALLS
> # ifndef __NR_clock_gettime64
> # define __NR_clock_gettime64 __NR_clock_gettime
> # define __vdso_clock_gettime64 __vdso_clock_gettime
> # endif
> return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> #else
> # if defined HAVE_CLOCK_GETTIME64_VSYSCALL
> int ret64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> if (ret64 == 0 || errno != ENOSYS)
> return ret64;
> # endif
> struct timespec tp32;
> int ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
> if (ret == 0)
> *tp = valid_timespec_to_timespec64 (tp32);
> return ret;
> #endif
Thanks for the review. I have updated it to do what you wrote above.
Alistair
>
>
> > + int ret_64;
> > + ret_64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
> > +
> > + if (ret_64 == 0 || errno != ENOSYS)
> > + return ret_64;
> > +# endif /* __NR_clock_gettime64 && HAVE_CLOCK_GETTIME64_VSYSCALL */
> > + int ret;
> > + struct timespec tp32;
> > +
> > + ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
> > +
> > + if (ret == 0)
> > + *tp = valid_timespec_to_timespec64 (tp32);
> > +
> > + return ret;
> > +#endif /* __ASSUME_TIME64_SYSCALLS */
>
> Ok.
>
> > +}
> > +
> > +#if __TIMESIZE != 64
> > +int
> > __clock_gettime (clockid_t clock_id, struct timespec *tp)
> > {
> > - return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
> > + int ret;
> > + struct __timespec64 tp64;
> > +
> > + ret = __clock_gettime64 (clock_id, &tp64);
> > +
> > + if (ret == 0)
> > + {
> > + if (! in_time_t_range (tp64.tv_sec))
> > + {
> > + __set_errno (EOVERFLOW);
> > + return -1;
> > + }
> > +
> > + *tp = valid_timespec64_to_timespec (tp64);
> > + }
> > +
> > + return ret;
> > }
> > +#endif
> > libc_hidden_def (__clock_gettime)
> >
> > versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);
>
> Ok.
@@ -211,11 +211,14 @@ extern double __difftime (time_t time1, time_t time0);
#if __TIMESIZE == 64
# define __clock_nanosleep_time64 __clock_nanosleep
+# define __clock_gettime64 __clock_gettime
#else
extern int __clock_nanosleep_time64 (clockid_t clock_id,
int flags, const struct __timespec64 *req,
struct __timespec64 *rem);
libc_hidden_proto (__clock_nanosleep_time64)
+extern int __clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp);
+libc_hidden_proto (__clock_gettime64)
#endif
/* Use in the clock_* functions. Size of the field representing the
@@ -17,6 +17,7 @@
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
+#include <kernel-features.h>
#include <errno.h>
#include <time.h>
#include "kernel-posix-cpu-timers.h"
@@ -30,10 +31,57 @@
/* Get current value of CLOCK and store it in TP. */
int
+__clock_gettime64 (clockid_t clock_id, struct __timespec64 *tp)
+{
+#ifdef __ASSUME_TIME64_SYSCALLS
+# ifndef __NR_clock_gettime64
+# define __NR_clock_gettime64 __NR_clock_gettime
+# define __vdso_clock_gettime64 __vdso_clock_gettime
+# endif
+ return INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
+#else
+# if defined __NR_clock_gettime64 && defined HAVE_CLOCK_GETTIME64_VSYSCALL
+ int ret_64;
+ ret_64 = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
+
+ if (ret_64 == 0 || errno != ENOSYS)
+ return ret_64;
+# endif /* __NR_clock_gettime64 && HAVE_CLOCK_GETTIME64_VSYSCALL */
+ int ret;
+ struct timespec tp32;
+
+ ret = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
+
+ if (ret == 0)
+ *tp = valid_timespec_to_timespec64 (tp32);
+
+ return ret;
+#endif /* __ASSUME_TIME64_SYSCALLS */
+}
+
+#if __TIMESIZE != 64
+int
__clock_gettime (clockid_t clock_id, struct timespec *tp)
{
- return INLINE_VSYSCALL (clock_gettime, 2, clock_id, tp);
+ int ret;
+ struct __timespec64 tp64;
+
+ ret = __clock_gettime64 (clock_id, &tp64);
+
+ if (ret == 0)
+ {
+ if (! in_time_t_range (tp64.tv_sec))
+ {
+ __set_errno (EOVERFLOW);
+ return -1;
+ }
+
+ *tp = valid_timespec64_to_timespec (tp64);
+ }
+
+ return ret;
}
+#endif
libc_hidden_def (__clock_gettime)
versioned_symbol (libc, __clock_gettime, clock_gettime, GLIBC_2_17);