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author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-07-10 17:03:49 -0300 |
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committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-07-12 17:37:56 -0300 |
commit | 72e84d1db22203e01a43268de71ea8669eca2863 (patch) | |
tree | 45eab8537afcfb66419a29d24a01c83dd9f9cde1 /posix | |
parent | aaacde11f2e814814fdd19dfb683e76f1dede4d5 (diff) | |
download | glibc-72e84d1db22203e01a43268de71ea8669eca2863.zip glibc-72e84d1db22203e01a43268de71ea8669eca2863.tar.gz glibc-72e84d1db22203e01a43268de71ea8669eca2863.tar.bz2 |
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>
Diffstat (limited to 'posix')
0 files changed, 0 insertions, 0 deletions