Re: [PATCH 1/2] userfaultfd.2: Add section for UFFD_USER_MODE_ONLY
From: Peter Xu
Date: Fri Jun 03 2022 - 13:34:29 EST
On Fri, Jun 03, 2022 at 07:11:05PM +0200, Alejandro Colomar wrote:
> Hi Peter,
>
> On 5/31/22 03:11, Peter Xu wrote:
> > Add a paragraph for UFFD_USER_MODE_ONLY flag that was introduced in
> > Linux 5.11.
> >
> > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
>
> See some minor comments below.
>
> Cheers,
>
> Alex
>
> > ---
> > man2/userfaultfd.2 | 14 ++++++++++++--
> > 1 file changed, 12 insertions(+), 2 deletions(-)
> >
> > diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2
> > index cee7c01d2..0928a76d2 100644
> > --- a/man2/userfaultfd.2
> > +++ b/man2/userfaultfd.2
> > @@ -29,8 +29,9 @@
> > userfaultfd \- create a file descriptor for handling page faults in user space
> > .SH SYNOPSIS
> > .nf
> > -.BR "#include <fcntl.h>" " /* Definition of " O_* " constants */"
> > -.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
> > +.BR "#include <fcntl.h>" " /* Definition of " O_* " constants */"
> > +.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
> > +.BR "#include <linux/userfaultfd.h>" " /* Definition of " UFFD_* " constants */"
> > .B #include <unistd.h>
> > .PP
> > .BI "int syscall(SYS_userfaultfd, int " flags );
> > @@ -76,6 +77,15 @@ See the description of the
> > .BR O_NONBLOCK
> > flag in
> > .BR open (2).
> > +.TP
> > +.BR UFFD_USER_MODE_ONLY
>
>
> s/BR/B/
>
> see groff_man(7):
>
> [
> [...]
>
> .B [text]
> Set text in bold. If the macro is given no argu‐
> ments, the text of the next input line is set in
> bold.
>
> [...]
>
> .BR bold‐text roman‐text ...
> Set each argument in bold and roman, alternately.
> ]
>
> > +This is an userfaultfd specific flag that was introduced since Linux 5.11.
> > +When set, the userfaultfd object will only be able to handle page faults
> > +originated from the userspace on the registered regions.
> > +When a kernel originated fault was triggered on the registered range with
> > +this userfaultfd, a
> > +.BR SIGBUS
>
> s/BR/B/
Thanks Alex, I'll fix and repost the patchset soon.
--
Peter Xu