Lukasz Majewski 177a3d48a1 y2038: linux: Provide __clock_getres64 implementation ... 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.		2019-10-27 21:49:25 +01:00
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linux	y2038: linux: Provide __clock_getres64 implementation	2019-10-27 21:49:25 +01:00