It breaks the usage case of live migration like CRIU or similar.
The performance drawback is it would require an extra syscall
on older kernels without 64-bit time support.
Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel
(with and without --enable-kernel=5.1) and on x86_64-linux-gnu.
Reviewed-by: Lukasz Majewski <lukma@denx.de>
The tst-timespec_getres (e5ac7bd679) triggers an issue on 32-bit
architecture on Linux older than 5.1, where the fallback syscall
is used.
Checked on powerpc-linux-gnu.
ISO C2X adds a timespec_getres function alongside the C11
timespec_get, with functionality similar to that of POSIX clock_getres
(including allowing a NULL pointer to be passed to the function).
Implement this function for glibc, similarly to the implementation of
timespec_get.
This includes a basic test like that of timespec_get, but no
documentation in the manual, given that TIME_UTC and timespec_get
aren't documented in the manual at all. The handling of 64-bit time
follows that in timespec_get; people maintaining patch series for
64-bit time will need to update them accordingly (to export
__timespec_getres64, redirect calls in time.h and run the test for
_TIME_BITS=64).
Tested for x86_64 and x86, and (previous version; only testcase
differs) with build-many-glibcs.py.
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
With arch-syscall.h it can now assumes the existance of either
__NR_clock_getres or __NR_clock_getres_time64. The 32-bit time_t
support is now only build for !__ASSUME_TIME64_SYSCALLS.
It also uses the time64-support functions to simplify it further.
Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15
kernel).
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
During the conversion to support 64 bit time on some architectures with
__WORDSIZE == 32 && __TIMESIZE != 64 the libc_hidden_def attribute for
eligible functions was by mistake omitted.
This patch fixes this issue and exports (and allows using) those
functions when Y2038 support is enabled in glibc.
This patch avoid probing the __NR_clock_getttime64 syscall each time
__clock_gettime64 is issued on a kernel without 64 bit time support.
Once ENOSYS is obtained, only 32-bit clock_gettime are used.
The following snippet:
clock_getres (CLOCK_REALTIME, &(struct timespec) { 0 });
clock_getres (CLOCK_MONOTONIC, &(struct timespec) { 0 });
clock_getres (CLOCK_BOOTTIME, &(struct timespec) { 0 });
clock_getres (20, &(struct timespec) { 0 });
On a kernel without 64 bit time support issues the syscalls:
syscall_0x196(0, 0xffb83330, [...]) = -1 ENOSYS (Function not implemented)
clock_getres(CLOCK_REALTIME, {tv_sec=0, tv_nsec=1}) = 0
clock_getres(CLOCK_MONOTONIC, {tv_sec=0, tv_nsec=1}) = 0
clock_getres(CLOCK_BOOTTIME, {tv_sec=0, tv_nsec=1}) = 0
Checked on i686-linux-gnu on 4.15 kernel.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
No architecture currently defines the vDSO symbol. On archictures
with 64-bit time_t the HAVE_CLOCK_GETRES_VSYSCALL is renamed to
HAVE_CLOCK_GETRES64_VSYSCALL, it simplifies clock_gettime code.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
As indicated on libc-help [1] the ec138c67cb commit broke 32-bit
builds when configured with --enable-kernel=5.1 or higher. The
scenario 10 from [2] might also occur in this configuration and
INLINE_VSYSCALL will try to use the vDSO symbol and
HAVE_CLOCK_GETTIME64_VSYSCALL does not set HAVE_VSYSCALL prior its
usage.
Also, there is no easy way to just enable the code to use one
vDSO symbol since the macro INLINE_VSYSCALL is redefined if
HAVE_VSYSCALL is set.
Instead of adding more pre-processor handling and making the code
even more convoluted, this patch removes the requirement of defining
HAVE_VSYSCALL before including sysdep-vdso.h to enable vDSO usage.
The INLINE_VSYSCALL is now expected to be issued inside a
HAVE_*_VSYSCALL check, since it will try to use the internal vDSO
pointers.
Both clock_getres and clock_gettime vDSO code for time64_t were
removed since there is no vDSO setup code for the symbol (an
architecture can not set HAVE_CLOCK_GETTIME64_VSYSCALL).
Checked on i686-linux-gnu (default and with --enable-kernel=5.1),
x86_64-linux-gnu, aarch64-linux-gnu, and powerpc64le-linux-gnu.
I also checked against a build to mips64-linux-gnu and
sparc64-linux-gnu.
[1] https://sourceware.org/ml/libc-help/2019-12/msg00014.html
[2] https://sourceware.org/ml/libc-alpha/2019-12/msg00142.html
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
This patch provides new __clock_getres64 explicit 64 bit function for
getting the resolution (precision) of specified clock ID. Moreover, a
32 bit version - __clock_getres has been refactored to internally use
__clock_getres64.
The __clock_getres is now supposed to be used on systems still supporting
32 bit time (__TIMESIZE != 64) - hence the necessary conversion from 64 bit
struct __timespec64 to struct timespec.
The new clock_getres_time64 syscall available from Linux 5.1+ has been used,
when applicable.
On systems which are not supporting clock_getres_time64 (as their
clock_getres supports 64 bit time ABI) the vDSO syscall is attempted.
On the contrary the non-vDSO syscall is used for clock_getres_time64 as
up till now the kernel is not providing such interface.
No additional checks (i.e. if tv_nsec value overflow) are performed on
values returned via clock_getres{_time64} syscall, as it is assumed that
the Linux kernel will either return 0 and provide correct value or error.
The check for tv_sec being out of range on systems still supporting 32 bit
time (__TIMESIZE != 64) without Y2038 time support is also omitted as it is
_very_ unlikely that we would have a timer with resolution which exceeds 32
bit time_t range.
Build tests:
- The code has been tested on x86_64/x86 (native compilation):
make PARALLELMFLAGS="-j8" && make xcheck PARALLELMFLAGS="-j8"
- The glibc has been build tested (make PARALLELMFLAGS="-j8") for
x86 (i386), x86_64-x32, and armv7
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
- Use of cross-test-ssh.sh for ARM (armv7):
make PARALLELMFLAGS="-j8" test-wrapper='./cross-test-ssh.sh root@192.168.7.2' xcheck
Linux kernel, headers and minimal kernel version for glibc build test
matrix:
- Linux v5.1 (with clock_getres_time64) 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_getres_time64 syscall.
- Linux v4.19 (no clock_getres_time64 support) with default minimal kernel
version for contemporary glibc
This kernel doesn't support clock_getres_time64 syscall, so the fallback
to clock_getres is tested.
The 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.
In glibc 2.17, the functions clock_getcpuclockid, clock_getres,
clock_gettime, clock_nanosleep, and clock_settime were moved from
librt.so to libc.so, leaving compatibility stubs behind. Now that the
dynamic linker no longer insists on finding versioned symbols in the
same library that originally defined them, we do not need the stubs
anymore, and this means we don't need GLIBC_PRIVATE __-prefix aliases
for most of the functions anymore either. (clock_gettime still needs
one.) For ports added before 2.17, libc.so needs to provide two
symbol versions for each, the default at GLIBC_2.17 plus a compat
version matching what librt had.
While I'm at it, move the clock_*.c files and their tests from rt/ to
time/.
Clock_gettime, settime and getres implementations are unncessarily
complex due to using defines and C file inclusion. Simplify the
code by replacing the redundant defines and removing the inclusion,
making it much easier to understand. No functional changes.
* sysdeps/posix/clock_getres.c (__clock_getres): Cleanup.
* sysdeps/unix/clock_gettime.c (__clock_gettime): Cleanup.
* sysdeps/unix/clock_settime.c (__clock_settime): Cleanup.
* sysdeps/unix/sysv/linux/clock_getres.c (__clock_getres): Cleanup.
* sysdeps/unix/sysv/linux/clock_gettime.c (__clock_gettime): Cleanup.
* sysdeps/unix/sysv/linux/clock_settime.c (__clock_settime): Cleanup.
This patch consolidate the Linux vDSO define and usage across all ports
that uses it. The common vDSO definitions and calling through
{INLINE/INTERNAL}_VSYSCALL macros are moved to a common header
sysdep-vdso.h and vDSO name declaration and prototype is defined
using a common macro.
Also PTR_{MANGLE,DEMANGLE} is added to ports that does not use them
for vDSO calls (aarch64, powerpc, s390, and tile) and thus it will
reflect in code changes. For ports that already implement pointer
mangling/demangling in vDSO system (i386, x32, x86_64) this patch
is mainly a code refactor.
Checked on x32, x86_64, x32, ppc64le, and aarch64.
Tom Gall <tom_gall@vnet.ibm.com>
* elf/rtld.c (dl_main): Initialize l_local_scope for sysinfo_map.
* sysdeps/powerpc/elf/libc-start.c: Move this...
* sysdeps/unix/sysv/linux/powerpc/libc-start.c: ...to here.
* sysdeps/powerpc/powerpc32/dl-start.S: Add _dl_main_dispatch label.
* sysdeps/powerpc/powerpc32/hp-timing.h: New file.
* sysdeps/unix/sysv/linux/powerpc/Versions: New file.
* sysdeps/unix/sysv/linux/clock_getres.c: If HAVE_CLOCK_GETRES_VSYSCALL
is not defined, redefine INTERNAL_VSYSCALL and INLINE_VSYSCALL to
INTERNAL_SYSCALL and INLINE_SYSCALL respectively. Otherwise include
<bits/libc-vdso.h>. Use INLINE_VSYSCALL and INTERNAL_SYSCALL instead
of the normal versions throughout the code.
* sysdeps/unix/sysv/linux/clock_gettime.c: Likewise if
HAVE_CLOCK_GETTIME_VSYSCALL is defined.
* sysdeps/unix/sysv/linux/powerpc/bits/libc-vdso.h: New file.
* sysdeps/unix/sysv/linux/powerpc/dl-vdso.c: New file.
* sysdeps/unix/sysv/linux/powerpc/dl-vdso.h: New file.
* sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c: Use vDSO.
* sysdeps/unix/sysv/linux/powerpc/gettimeofday.c: New file.
* sysdeps/unix/sysv/linux/powerpc/Makefile: Add dl-vdso to routines.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/sysdep.h: Define
INLINE_VSYSCALL, INTERNAL_VSYSCALL, INTERNAL_SYSCALL_NCS,
INTERNAL_VSYSCALL_NO_SYSCALL_FALLBACK, HAVE_CLOCK_GETRES_VSYSCALL,
and HAVE_CLOCK_GETTIME_VSYSCALL.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h: Likewise.
* sysdeps/unix/sysv/linux/kernel-posix-cpu-timers.h: New file.
* sysdeps/unix/sysv/linux/clock_getcpuclockid.c: New file.
* sysdeps/unix/sysv/linux/ia64/clock_getcpuclockid.c
(HAS_CPUCLOCK): New macro.
(clock_getcpuclockid): Function removed.
#include the new linux file to define it instead.
* sysdeps/unix/clock_gettime.c [HP_TIMING_AVAIL] (hp_timing_gettime):
New function, broken out of ...
(clock_gettime) [HP_TIMING_AVAIL]: ... here. Call it.
(realtime_gettime): New function, broken out of ...
(clock_gettime) [! HANDLED_REALTIME]: ... here. Call it.
(clock_gettime) [SYSDEP_GETTIME_CPU]: Use new macro in default case.
* sysdeps/unix/sysv/linux/clock_gettime.c (SYSCALL_GETTIME): New macro.
(SYSDEP_GETTIME_CPUTIME): New macro.
(SYSDEP_GETTIME): Use both.
[! __ASSUME_POSIX_TIMERS] (maybe_syscall_gettime): New function, broken
out of ...
(SYSDEP_GETTIME): ... here. Use it.
[__NR_clock_gettime] (HANDLED_CPUTIME): Define it.
(SYSDEP_GETTIME_CPUTIME): New macro. Handle CPU timers by trying
kernel support and falling back to hp-timing code.
* sysdeps/posix/clock_getres.c
[HP_TIMING_AVAIL] (hp_timing_getres): New function, broken out of ...
(clock_getres) [HP_TIMING_AVAIL]: ... here. Call it.
(realtime_getres): New function, broken out of ...
(clock_getres) [! HANDLED_REALTIME]: ... here. Call it.
(clock_getres) [SYSDEP_GETRES_CPU]: Use new macro in default case.
* sysdeps/unix/sysv/linux/clock_getres.c (SYSCALL_GETRES): New macro.
(SYSDEP_GETRES_CPUTIME): New macro.
(SYSDEP_GETRES): Use both.
[! __ASSUME_POSIX_TIMERS] (maybe_syscall_getres): New function, broken
out of ...
(SYSDEP_GETRES): ... here. Use it.
[__NR_clock_getres] (HANDLED_CPUTIME): Define it.
(SYSDEP_GETRES_CPUTIME): New macro. Handle CPU timers by trying
kernel support and falling back to hp-timing code.
* sysdeps/unix/sysv/linux/clock_nanosleep.c: Handle
CLOCK_PROCESS_CPUTIME_ID and CLOCK_PROCESS_THREAD_ID specially,
translating to the kernel clockid_t for our own process/thread clock.
