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

["Günther Noack" <gnoack3000@gmail.com>]

Hello Jiri!

Sorry to revive this old thread with a meta-question...

We were discussing the workflow of using a single patch set for
sending man pages together with kernel changes, and Alejandro pointed
out on https://lwn.net/Articles/989398/ that you have been doing this
in the past on this and other threads.

I have been trying to reconstruct how you have done this, and so far,
my best guess is that the process is to:

1. `git fetch` the man pages project into the same local repo where
   you keep the kernel tree;
   
2. prepare man page patches and kernel patches in that same repo
   (probably using the git worktree feature);
   
3. git format-patch with --subject-prefix="PATCH bpf-next" and a
   revision range that gives both "dotted ranges" at the same time, e.g.

   git format-patch -v23 --cover-letter \
       linux-master..mylinuxbranch man-master..mymanbranch

4. In the resulting mail files, hand-edit the subject prefix in the
   man page commit, in addition to the cover letter.

Is that an accurate description of your process?  Or am I overlooking
another trick or tool that I could use here?  Is this a practice that
other people are using as well?

Thanks,
–-Günther

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@kernel.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@kernel.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.
> +
> +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()
> +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
>