Hello Arnd, Arnd Bergmann <arnd@xxxxxxxx> writes: > On Tue, Sep 21, 2021 at 3:01 PM Richard Palethorpe <rpalethorpe@xxxxxxxx> wrote: >> >> The LTP test io_pgetevents02 fails in 32bit compat mode because an >> nr_max of -1 appears to be treated as a large positive integer. This >> causes pgetevents_time64 to return an event. The test expects the call >> to fail and errno to be set to EINVAL. >> >> Using the compat syscall fixes the issue. >> >> Fixes: 7a35397f8c06 ("io_pgetevents: use __kernel_timespec") >> Signed-off-by: Richard Palethorpe <rpalethorpe@xxxxxxxx> > > Thanks a lot for finding this, indeed there is definitely a mistake that > this function is defined and not used, but I don't yet see how it would > get to the specific failure you report. > > Between the two implementations, I can see a difference in the > handling of the signal mask, but that should only affect architectures > with incompatible compat_sigset_t, i.e. big-endian or > _COMPAT_NSIG_WORDS!=_NSIG_WORDS, and the latter is > never true for currently supported architectures. On x86, there is > no difference in the sigset at all. > > The negative 'nr' and 'min_nr' arguments that you list as causing > the problem /should/ be converted by the magic > SYSCALL_DEFINE6() definition. If this is currently broken, I would > expect other syscalls to be affected as well. That is what I thought, but I couldn't think of another explanation for it. > > Have you tried reproducing this on non-x86 architectures? If I > misremembered how the compat conversion in SYSCALL_DEFINE6() > works, then all architectures that support CONFIG_COMPAT have > to be fixed. > > Arnd No, but I suppose I can try it on ARM or PowerPC. I suppose printing the arguments would be a good idea too. -- Thank you, Richard.