On Tue, Apr 23, 2024 at 12:07:29AM +0900, Masami Hiramatsu wrote: > On Sun, 21 Apr 2024 21:42:06 +0200 > Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > > > Adding man page for new uretprobe syscall. > > > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> > > --- > > man2/uretprobe.2 | 40 ++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 40 insertions(+) > > create mode 100644 man2/uretprobe.2 > > > > diff --git a/man2/uretprobe.2 b/man2/uretprobe.2 > > new file mode 100644 > > index 000000000000..c0343a88bb57 > > --- /dev/null > > +++ b/man2/uretprobe.2 > > @@ -0,0 +1,40 @@ > > +.\" Copyright (C) 2024, Jiri Olsa <jolsa@xxxxxxxxxx> > > +.\" > > +.\" SPDX-License-Identifier: Linux-man-pages-copyleft > > +.\" > > +.TH uretprobe 2 (date) "Linux man-pages (unreleased)" > > +.SH NAME > > +uretprobe \- execute pending return uprobes > > +.SH SYNOPSIS > > +.nf > > +.B int uretprobe(void) > > +.fi > > +.SH DESCRIPTION > > +On x86_64 architecture the kernel is using uretprobe syscall to trigger > > +uprobe return probe consumers instead of using standard breakpoint instruction. > > +The reason is that it's much faster to do syscall than breakpoint trap > > +on x86_64 architecture. > > Do we specify the supported architecture as this? Currently it is supported > only on x86-64, but it could be extended later, right? yes, that's the idea, but I can't really speak other than x86 ;-) so not sure abour other archs details > > This should be just noted as NOTES. Something like "This syscall is initially > introduced on x86-64 because a syscall is faster than a breakpoint trap on it. > But this will be extended to the architectures whose syscall is faster than > breakpoint trap." 's/will be extended/might be will be extended/' seems better to me, other than that it looks ok thanks, jirka > > Thank you, > > > + > > +The uretprobe syscall is not supposed to be called directly by user, it's allowed > > +to be invoked only through user space trampoline provided by kernel. > > +When called from outside of this trampoline, the calling process will receive > > +.BR SIGILL . > > + > > +.SH RETURN VALUE > > +.BR uretprobe() > > +return value is specific for given architecture. > > + > > +.SH VERSIONS > > +This syscall is not specified in POSIX, > > +and details of its behavior vary across systems. > > +.SH STANDARDS > > +None. > > +.SH NOTES > > +.BR uretprobe() > > +exists only to allow the invocation of return uprobe consumers. > > +It should > > +.B never > > +be called directly. > > +Details of the arguments (if any) passed to > > +.BR uretprobe () > > +and the return value are specific for given architecture. > > -- > > 2.44.0 > > > > > -- > Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
