linux-kernel - Re: [PATCHv4 7/7] man2: Add uretprobe syscall page

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Message-ID: <ZjOYf_g2qRrhDoQD@debian>
Date: Thu, 2 May 2024 15:43:27 +0200
From: Alejandro Colomar <alx@...nel.org>
To: Jiri Olsa <jolsa@...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>
Subject: Re: [PATCHv4 7/7] man2: Add uretprobe syscall page

Hi Jiri,

On Thu, May 02, 2024 at 02:23:13PM +0200, Jiri Olsa wrote:
> Adding man page for new uretprobe syscall.
> 
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  man2/uretprobe.2 | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
>  create mode 100644 man2/uretprobe.2
> 
> diff --git a/man2/uretprobe.2 b/man2/uretprobe.2
> new file mode 100644
> index 000000000000..08fe6a670430
> --- /dev/null
> +++ b/man2/uretprobe.2
> @@ -0,0 +1,45 @@
> +.\" 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
> +.SH DESCRIPTION
> +Kernel is using
> +.BR uretprobe()
> +syscall to trigger uprobe return probe consumers instead of using
> +standard breakpoint instruction.
> +

Please use .P instead of a blank.  See man-pages(7):

   Formatting conventions (general)
     Paragraphs should be separated by suitable markers (usually either
     .P or .IP).  Do not separate paragraphs using blank lines, as this
     results in poor rendering in some output formats  (such  as  Post‐
     Script and PDF).

> +The uretprobe syscall is not supposed to be called directly by user, it's allowed

s/by user/by the user/

> +to be invoked only through user space trampoline provided by kernel.

s/user space/user-space/

Missing a few 'the' too, here and in the rest of the page.

> +When called from outside of this trampoline, the calling process will receive
> +.BR SIGILL .
> +
> +.SH RETURN VALUE
> +.BR uretprobe()

You're missing a space here:

.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.

You could add a HISTORY section.

Have a lovely day!
Alex

> +.SH NOTES
> +.BR uretprobe()
> +syscall is initially introduced on x86-64 architecture, because doing syscall
> +is faster than doing breakpoint trap on it. It might be extended to other
> +architectures.
> +
> +.BR uretprobe()
> +syscall 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
> 
> 

-- 
<https://www.alejandro-colomar.es/>
A client is hiring kernel driver, mm, and/or crypto developers;
contact me if interested.

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