linux-kernel - Re: [PATCHv6 9/9] man2: Add uretprobe syscall page

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Message-ID: <ZkyKKwfhNZxrGWsa@krava>
Date: Tue, 21 May 2024 13:48:59 +0200
From: Jiri Olsa <olsajiri@...il.com>
To: Alejandro Colomar <alx@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org, linux-api@...r.kernel.org,
	linux-man@...r.kernel.org, x86@...nel.org, bpf@...r.kernel.org,
	Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
	John Fastabend <john.fastabend@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Borislav Petkov (AMD)" <bp@...en8.de>,
	Ingo Molnar <mingo@...hat.com>, Andy Lutomirski <luto@...nel.org>,
	"Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
	Deepak Gupta <debug@...osinc.com>
Subject: Re: [PATCHv6 9/9] man2: Add uretprobe syscall page

On Tue, May 21, 2024 at 01:36:25PM +0200, Alejandro Colomar wrote:
> Hi Jiri,
> 
> On Tue, May 21, 2024 at 12:48:25PM GMT, Jiri Olsa wrote:
> > Adding man page for new uretprobe syscall.
> > 
> > Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> > ---
> >  man2/uretprobe.2 | 50 ++++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 50 insertions(+)
> >  create mode 100644 man2/uretprobe.2
> > 
> > diff --git a/man2/uretprobe.2 b/man2/uretprobe.2
> > new file mode 100644
> > index 000000000000..690fe3b1a44f
> > --- /dev/null
> > +++ b/man2/uretprobe.2
> > @@ -0,0 +1,50 @@
> > +.\" Copyright (C) 2024, Jiri Olsa <jolsa@...nel.org>
> > +.\"
> > +.\" 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
> 
> What header file provides this system call?

there's no header, it's used/called only by user space trampoline
provided by kernel, it's not expected to be called by user

> 
> > +.SH DESCRIPTION
> > +The
> > +.BR uretprobe ()
> > +syscall is an alternative to breakpoint instructions for
> > +triggering return uprobe consumers.
> > +.P
> > +Calls to
> > +.BR uretprobe ()
> > +suscall are only made from the user-space trampoline provided by the kernel.
> 
> s/suscall/system call/

ugh leftover sry

> 
> > +Calls from any other place result in a
> > +.BR SIGILL .
> 
> Maybe add an ERRORS section?
> 
> > +
> 
> We don't use blank lines; it causes a groff(1) warning, and other
> problems.  Instead, use '.P'.
> 
> > +.SH RETURN VALUE
> > +The
> > +.BR uretprobe ()
> > +syscall return value is architecture-specific.
> > +
> 
> .P
> 
> > +.SH VERSIONS
> > +This syscall is not specified in POSIX,
> 
> Redundant with "STANDARDS: None.".
> 
> > +and details of its behavior vary across systems.
> 
> Keep this.

ok

> 
> > +.SH STANDARDS
> > +None.
> > +.SH HISTORY
> > +TBD
> > +.SH NOTES
> > +The
> > +.BR uretprobe ()
> > +syscall was initially introduced for the x86_64 architecture where it was shown
> > +to be faster than breakpoint traps. It might be extended to other architectures.
> 
> Please use semantic newlines.
> 
> $ MANWIDTH=72 man man-pages | sed -n '/Use semantic newlines/,/^$/p'
>    Use semantic newlines
>      In the source of a manual page, new sentences should be started on
>      new lines, long sentences should be split  into  lines  at  clause
>      breaks  (commas,  semicolons, colons, and so on), and long clauses
>      should be split at phrase boundaries.  This convention,  sometimes
>      known as "semantic newlines", makes it easier to see the effect of
>      patches, which often operate at the level of individual sentences,
>      clauses, or phrases.

ok

thanks,
jirka

> 
> > +.P
> > +The
> > +.BR uretprobe ()
> > +syscall exists only to allow the invocation of return uprobe consumers.
> 
> s/syscall/system call/
> 
> > +It should
> > +.B never
> > +be called directly.
> > +Details of the arguments (if any) passed to
> > +.BR uretprobe ()
> > +and the return value are architecture-specific.
> > -- 
> > 2.44.0
> 
> Have a lovely day!
> Alex
> 
> -- 
> <https://www.alejandro-colomar.es/>