The previous approach defeats the vDSO optimization on older kernels
because a failing clock_gettime64 system call is performed on every
function call. It also results in a clobbered errno value, exposing
an OpenJDK bug (JDK-
8270244).
This patch fixes by open-code INLINE_VSYSCALL macro and replace all
INLINE_SYSCALL_CALL with INTERNAL_SYSCALL_CALLS. Now for
__clock_gettime64x, the 64-bit vDSO is used and the 32-bit vDSO is
tried before falling back to 64-bit syscalls.
The previous code preferred 64-bit syscall for the case where the kernel
provides 64-bit time_t syscalls *and* also a 32-bit vDSO (in this case
the *64-bit* syscall should be preferable over the vDSO). All
architectures that provides 32-bit vDSO (i386, mips, powerpc, s390)
modulo sparc; but I am not sure if some kernels versions do provide
only 32-bit vDSO while still providing 64-bit time_t syscall.
Regardless, for such cases the 64-bit time_t syscall is used if the
vDSO returns overflowed 32-bit time_t.
Tested on i686-linux-gnu (with a time64 and non-time64 kernel),
x86_64-linux-gnu. Built with build-many-glibcs.py.
Co-authored-by: Florian Weimer <fweimer@redhat.com>
sysdep_headers += sys/timex.h bits/timex.h
sysdep_routines += ntp_gettime ntp_gettimex
+
+tests += \
+ tst-clock_gettime-clobber \
+ tst-gettimeofday-clobber \
+ tst-time-clobber \
+ # tests
endif
ifeq ($(subdir),signal)
#endif
#ifdef HAVE_CLOCK_GETTIME64_VSYSCALL
- r = INLINE_VSYSCALL (clock_gettime64, 2, clock_id, tp);
-#else
- r = INLINE_SYSCALL_CALL (clock_gettime64, clock_id, tp);
+ int (*vdso_time64) (clockid_t clock_id, struct __timespec64 *tp)
+ = GLRO(dl_vdso_clock_gettime64);
+ if (vdso_time64 != NULL)
+ {
+ r = INTERNAL_VSYSCALL_CALL (vdso_time64, 2, clock_id, tp);
+ if (r == 0)
+ return 0;
+ return INLINE_SYSCALL_ERROR_RETURN_VALUE (-r);
+ }
#endif
- if (r == 0 || errno != ENOSYS)
- return r;
+#ifdef HAVE_CLOCK_GETTIME_VSYSCALL
+ int (*vdso_time) (clockid_t clock_id, struct timespec *tp)
+ = GLRO(dl_vdso_clock_gettime);
+ if (vdso_time != NULL)
+ {
+ struct timespec tp32;
+ r = INTERNAL_VSYSCALL_CALL (vdso_time, 2, clock_id, &tp32);
+ if (r == 0 && tp32.tv_sec > 0)
+ {
+ *tp = valid_timespec_to_timespec64 (tp32);
+ return 0;
+ }
+ else if (r != 0)
+ return INLINE_SYSCALL_ERROR_RETURN_VALUE (-r);
+
+ /* Fallback to syscall if the 32-bit time_t vDSO returns overflows. */
+ }
+#endif
+
+ r = INTERNAL_SYSCALL_CALL (clock_gettime64, clock_id, tp);
+ if (r == 0)
+ return 0;
+ if (r != -ENOSYS)
+ return INLINE_SYSCALL_ERROR_RETURN_VALUE (-r);
#ifndef __ASSUME_TIME64_SYSCALLS
/* Fallback code that uses 32-bit support. */
struct timespec tp32;
-# ifdef HAVE_CLOCK_GETTIME_VSYSCALL
- r = INLINE_VSYSCALL (clock_gettime, 2, clock_id, &tp32);
-# else
- r = INLINE_SYSCALL_CALL (clock_gettime, clock_id, &tp32);
-# endif
+ r = INTERNAL_SYSCALL_CALL (clock_gettime, clock_id, &tp32);
if (r == 0)
- *tp = valid_timespec_to_timespec64 (tp32);
+ {
+ *tp = valid_timespec_to_timespec64 (tp32);
+ return 0;
+ }
#endif
- return r;
+ return INLINE_SYSCALL_ERROR_RETURN_VALUE (-r);
}
#if __TIMESIZE != 64
--- /dev/null
+/* Check that clock_gettime does not clobber errno on success.
+ Copyright (C) 2021 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; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <time.h>
+#include <support/check.h>
+#include <stdio.h>
+
+static void
+test_clock (clockid_t clk)
+{
+ printf ("info: testing clock: %d\n", (int) clk);
+
+ for (int original_errno = 0; original_errno < 2; ++original_errno)
+ {
+ errno = original_errno;
+ struct timespec ts;
+ if (clock_gettime (clk, &ts) == 0)
+ TEST_COMPARE (errno, original_errno);
+ }
+}
+
+static int
+do_test (void)
+{
+ test_clock (CLOCK_BOOTTIME);
+ test_clock (CLOCK_BOOTTIME_ALARM);
+ test_clock (CLOCK_MONOTONIC);
+ test_clock (CLOCK_MONOTONIC_COARSE);
+ test_clock (CLOCK_MONOTONIC_RAW);
+ test_clock (CLOCK_PROCESS_CPUTIME_ID);
+ test_clock (CLOCK_REALTIME);
+ test_clock (CLOCK_REALTIME_ALARM);
+ test_clock (CLOCK_REALTIME_COARSE);
+#ifdef CLOCK_TAI
+ test_clock (CLOCK_TAI);
+#endif
+ test_clock (CLOCK_THREAD_CPUTIME_ID);
+ return 0;
+}
+
+#include <support/test-driver.c>
--- /dev/null
+/* Check that gettimeofday does not clobber errno.
+ Copyright (C) 2021 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; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <stddef.h>
+#include <support/check.h>
+#include <sys/time.h>
+
+static int
+do_test (void)
+{
+ for (int original_errno = 0; original_errno < 2; ++original_errno)
+ {
+ errno = original_errno;
+ struct timeval tv;
+ gettimeofday (&tv, NULL);
+ TEST_COMPARE (errno, original_errno);
+ }
+ return 0;
+}
+
+#include <support/test-driver.c>
--- /dev/null
+/* Check that time does not clobber errno.
+ Copyright (C) 2021 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; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <stddef.h>
+#include <support/check.h>
+#include <time.h>
+
+static int
+do_test (void)
+{
+ for (int original_errno = 0; original_errno < 2; ++original_errno)
+ {
+ errno = original_errno;
+ time (NULL);
+ TEST_COMPARE (errno, original_errno);
+ }
+ return 0;
+}
+
+#include <support/test-driver.c>
projects / platform / upstream / glibc.git / commitdiff