linux-kernel - Re: [PATCH bootconfig 2/3] fs/proc: Add boot loader arguments as comment to /proc/bootconfig

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Message-ID: <55067c09-9ec6-452a-a6db-30b8a8d08485@paulmck-laptop>
Date:   Fri, 6 Oct 2023 09:52:30 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-doc@...r.kernel.org, Jonathan Corbet <corbet@....net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Arnd Bergmann <arnd@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH bootconfig 2/3] fs/proc: Add boot loader arguments as
 comment to /proc/bootconfig

On Fri, Oct 06, 2023 at 05:59:48PM +0900, Masami Hiramatsu wrote:
> On Thu,  5 Oct 2023 10:17:46 -0700
> "Paul E. McKenney" <paulmck@...nel.org> wrote:
> 
> > In kernels built with CONFIG_BOOT_CONFIG_FORCE=y, /proc/cmdline will
> > show all kernel boot parameters, both those supplied by the boot loader
> > and those embedded in the kernel image.  This works well for those who
> > just want to see all of the kernel boot parameters, but is not helpful to
> > those who need to see only those parameters supplied by the boot loader.
> > This is especially important when these parameters are presented to the
> > boot loader by automation that might gather them from diverse sources.
> > It is also useful when booting the next kernel via kexec(), in which
> > case it is necessary to supply only those kernel command-line arguments
> > from the boot loader, and most definitely not those that were embedded
> > into the current kernel.
> > 
> > Therefore, add comments to /proc/bootconfig of the form:
> > 
> > 	# Parameters from bootloader:
> > 	# root=UUID=ac0f0548-a69d-43ca-a06b-7db01bcbd5ad ro quiet ...
> > 
> > The second added line shows only those kernel boot parameters supplied
> > by the boot loader.
> 
> Thanks for update it.
> 
> This looks good to me.
> 
> Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
> 
> Thank you!

And thank you!  I take this as meaning that I should push these three
commits for the upcoming v6.7 merge window.  Please let me know if I
should be doing something else.

							Thanx, Paul

> > Link: https://lore.kernel.org/all/CAHk-=wjpVAW3iRq_bfKnVfs0ZtASh_aT67bQBG11b4W6niYVUw@mail.gmail.com/
> > Link: https://lore.kernel.org/all/20230731233130.424913-1-paulmck@kernel.org/
> > Co-developed-by: Masami Hiramatsu <mhiramat@...nel.org>
> > Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> > Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> > Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> > Cc: Stephen Rothwell <sfr@...b.auug.org.au>
> > Cc: Arnd Bergmann <arnd@...nel.org>
> > Cc: Nick Desaulniers <ndesaulniers@...gle.com>
> > Cc: Alexey Dobriyan <adobriyan@...il.com>
> > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > Cc: Kees Cook <keescook@...omium.org>
> > Cc: <linux-trace-kernel@...r.kernel.org>
> > Cc: <linux-fsdevel@...r.kernel.org>
> > ---
> >  fs/proc/bootconfig.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/fs/proc/bootconfig.c b/fs/proc/bootconfig.c
> > index 2e244ada1f97..902b326e1e56 100644
> > --- a/fs/proc/bootconfig.c
> > +++ b/fs/proc/bootconfig.c
> > @@ -62,6 +62,12 @@ static int __init copy_xbc_key_value_list(char *dst, size_t size)
> >  				break;
> >  			dst += ret;
> >  		}
> > +		if (ret >= 0 && boot_command_line[0]) {
> > +			ret = snprintf(dst, rest(dst, end), "# Parameters from bootloader:\n# %s\n",
> > +				       boot_command_line);
> > +			if (ret > 0)
> > +				dst += ret;
> > +		}
> >  	}
> >  out:
> >  	kfree(key);
> > -- 
> > 2.40.1
> > 
> 
> 
> -- 
> Masami Hiramatsu (Google) <mhiramat@...nel.org>