[PATCH v5] sysdeps/clock_nanosleep: Use clock_nanosleep_time64 if avaliable
Lukasz Majewski
lukma@denx.de
Fri Nov 8 12:54:00 GMT 2019
Hi Alistair,
Please find my comments regarding checking of NULL pointers.
> The clock_nanosleep syscall is not supported on newer 32-bit
> platforms (such as RV32). To fix this issue let's use
> clock_nanosleep_time64 if it is avaliable.
> ---
> 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
>
> v5:
> - Fix clock_nanosleep syscall
> - Rebase on master
>
> v4:
> - Rebase on master
> - Use __clock_nanosleep to avoid duplicate implementations
> - Fix the error handling when a syscall fails
> v2:
> - Explicitly include `#include <kernel-features.h>`
>
> include/time.h | 20 +++++++
> sysdeps/unix/sysv/linux/clock_nanosleep.c | 66
> +++++++++++++++++++++-- 2 files changed, 81 insertions(+), 5
> deletions(-)
>
> diff --git a/include/time.h b/include/time.h
> index b3e635395db..03389bda290 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -209,6 +209,26 @@ libc_hidden_proto (__difftime64)
>
> extern double __difftime (time_t time1, time_t time0);
>
> +#if __TIMESIZE == 64
> +# define __thrd_sleep_time64 thrd_sleep
> +# define __clock_nanosleep_time64 __clock_nanosleep
> +# define __nanosleep_time64 __nanosleep
> +# define __nanosleep_nocancel_time64 __nanosleep_nocancel
> +#else
> +extern int __thrd_sleep_time64 (const struct __timespec64*
> time_point,
> + struct __timespec64* remaining);
> +libc_hidden_proto (__thrd_sleep_time64)
> +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 __nanosleep_time64 (const struct __timespec64
> *requested_time,
> + struct __timespec64 *remaining);
> +libc_hidden_proto (__nanosleep_time64)
> +extern int __nanosleep_nocancel_time64 (const struct __timespec64
> *requested_time,
> + struct __timespec64
> *remaining); +libc_hidden_proto (__nanosleep_nocancel_time64)
> +#endif
>
> /* Use in the clock_* functions. Size of the field representing the
> actual clock ID. */
> diff --git a/sysdeps/unix/sysv/linux/clock_nanosleep.c
> b/sysdeps/unix/sysv/linux/clock_nanosleep.c index
> f3c6fd2d5f7..7212dcf9c6d 100644 ---
> a/sysdeps/unix/sysv/linux/clock_nanosleep.c +++
> b/sysdeps/unix/sysv/linux/clock_nanosleep.c @@ -16,6 +16,7 @@
> <https://www.gnu.org/licenses/>. */
>
> #include <time.h>
> +#include <kernel-features.h>
> #include <errno.h>
>
> #include <sysdep-cancel.h>
> @@ -26,9 +27,11 @@
> /* We can simply use the syscall. The CPU clocks are not supported
> with this function. */
> int
> -__clock_nanosleep (clockid_t clock_id, int flags, const struct
> timespec *req,
> - struct timespec *rem)
> +__clock_nanosleep_time64 (clockid_t clock_id, int flags, const
> struct __timespec64 *req,
> + struct __timespec64 *rem)
> {
> + int r;
> +
> if (clock_id == CLOCK_THREAD_CPUTIME_ID)
> return EINVAL;
> if (clock_id == CLOCK_PROCESS_CPUTIME_ID)
> @@ -37,11 +40,64 @@ __clock_nanosleep (clockid_t clock_id, int flags,
> const struct timespec *req, /* If the call is interrupted by a signal
> handler or encounters an error, it returns a positive value similar
> to errno. */ INTERNAL_SYSCALL_DECL (err);
> - int r = INTERNAL_SYSCALL_CANCEL (clock_nanosleep, err, clock_id,
> flags,
> - req, rem);
> +
> +#ifdef __ASSUME_TIME64_SYSCALLS
> +# ifndef __NR_clock_nanosleep_time64
> +# define __NR_clock_nanosleep_time64 __NR_clock_nanosleep
> +# endif
> + r = INTERNAL_SYSCALL_CANCEL (clock_nanosleep_time64, err, clock_id,
> + flags, req, rem);
> +#else
> +# ifdef __NR_clock_nanosleep_time64
> + r = INTERNAL_SYSCALL_CANCEL (clock_nanosleep_time64, err, clock_id,
> + flags, req, rem);
> +
> + if (r == 0 || errno != ENOSYS)
> + {
> + return (INTERNAL_SYSCALL_ERROR_P (r, err)
> + ? INTERNAL_SYSCALL_ERRNO (r, err) : 0);
> + }
> +# endif /* __NR_clock_nanosleep_time64 */
> + struct timespec ts32, tr32;
> +
> + if (! in_time_t_range (req->tv_sec))
> + {
> + __set_errno (EOVERFLOW);
> + return -1;
> + }
> +
> + ts32 = valid_timespec64_to_timespec (*req);
Here we don't need to check req == NULL, as we will go into this piece
of code only for 32 bit systems (and kernel < 5.1) with glibc's local
copy of struct __timespec64.
> + r = INTERNAL_SYSCALL_CANCEL (clock_nanosleep, err, clock_id,
> flags,
> + &ts32, &tr32);
> +
> + if ((r == 0 || errno != ENOSYS) && rem)
> + *rem = valid_timespec_to_timespec64 (tr32);
> +#endif /* __ASSUME_TIME64_SYSCALLS */
> +
> return (INTERNAL_SYSCALL_ERROR_P (r, err)
> - ? INTERNAL_SYSCALL_ERRNO (r, err) : 0);
> + ? INTERNAL_SYSCALL_ERRNO (r, err) : 0);
> }
> +
> +#if __TIMESIZE != 64
> +int
> +__clock_nanosleep (clockid_t clock_id, int flags, const struct
> timespec *req,
> + struct timespec *rem)
> +{
> + int r;
> + struct __timespec64 treq64, trem64;
> +
^^^^^^^^^^^^ - [*]
> + treq64 = valid_timespec_to_timespec64 (*req);
The above line would cause regression. Please find below explanation:
The check on *rqtp (in Linux kernel's clock_nanosleep syscall handling):
https://elixir.bootlin.com/linux/v5.4-rc5/source/kernel/time/posix-timers.c#L1220
When compiling test program with clock_nanosleep() passing *request [1]
as NULL [3] - the clock_nanosleep returns 14, which corresponds to
#define EFAULT 14 [2] (which matches [1]).
Hence we should have following code in [*]:
if (req == NULL)
{
__set_errno(EFAULT)
returm 1;
}
Otherwise we will break in glibc before we enter the clock_nanosleep
syscall (which would then return with proper error code).
Links:
[1] - http://man7.org/linux/man-pages/man2/clock_nanosleep.2.html
[2] - cpp -dM /usr/include/errno.h | grep 'define E' | sort -n -k 3
[3] - test program:
int main(int argc, char **argv)
{
int result;
result = clock_nanosleep(CLOCK_REALTIME, 0 /* relative */,
NULL, NULL);
if (result)
printf("clock_nanosleep: %d\n", result);
return 0;
}
> + r = __clock_nanosleep_time64 (clock_id, flags, &treq64, &trem64);
> +
> + if (r == 0 || errno != ENOSYS)
> + {
> + if (rem)
> + *rem = valid_timespec64_to_timespec (trem64);
> + }
> +
> + return r;
> +}
> +#endif
> libc_hidden_def (__clock_nanosleep)
> versioned_symbol (libc, __clock_nanosleep, clock_nanosleep,
> GLIBC_2_17); /* clock_nanosleep moved to libc in version 2.17;
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
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