Hi Dave, On 10/18/2016 12:07 AM, Dave Hansen wrote: > From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > The signal behavior of pkeys is special compared to many other > processor and OS features. Add a special section to describe > the behavior. > > This was previously a part of the pkey_get manpage, but that > page was removed from my submission when we removed the > syscall itself. I've essentially moved the content from that > page to the main pkey.7 page. Thank. Patch applied. Cheers, Michael > > Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > --- > > b/man7/pkeys.7 | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff -puN man7/pkeys.7~pkey-signal-behavior man7/pkeys.7 > --- a/man7/pkeys.7~pkey-signal-behavior 2016-10-17 08:59:31.081217165 -0700 > +++ b/man7/pkeys.7 2016-10-17 13:36:48.525030174 -0700 > @@ -135,6 +135,22 @@ appropriate for child threads at the tim > .BR clone (2) > is called, or ensure that each child thread can perform its > own initialization of protection key rights. > + > +.SS Signal Handler Behavior > +Each time a signal handler is invoked (including nested signals), the > +thread is temporarily given a new, default set of protection key rights > +that override the rights from the interrupted context. > +This means that applications must re-establish their desired protection > +key rights upon entering a signal handler if the desired rights differ > +from the defaults. > +The rights of any interrupted context are restored when the signal > +handler returns. > + > +This signal behavior is unusual and is due to the fact that the x86 PKRU > +register (which stores protection key access rights) is managed with the > +same hardware mechanism (XSAVE) that manages floating-point registers. > +The signal behavior is the same as that of floating point registers. > + > .SS Protection Keys system calls > The Linux kernel implements the following pkey-related system calls: > .BR pkey_mprotect (2), > _ > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
