Adhemerval Zanella 72e84d1db2 Linux: Use 32-bit vDSO for clock_gettime, gettimeofday, time (BZ# 28071) ... 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>		2021-07-12 17:37:56 -03:00
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linux	Linux: Use 32-bit vDSO for clock_gettime, gettimeofday, time (BZ# 28071)	2021-07-12 17:37:56 -03:00