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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 12 Sep 2022 10:09:38 -0400
Message-ID: <CAHk-=whRetwx+5Bjiee+T+Nyyi8EiZ17SM3AL8jJnXuA+WjQyQ@mail.gmail.com>
Subject: Re: [PATCH v2 08/59] x86/build: Ensure proper function alignment
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        x86@kernel.org, Tim Chen <tim.c.chen@linux.intel.com>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Andrew Cooper <Andrew.Cooper3@citrix.com>,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Johannes Wikner <kwikner@ethz.ch>,
        Alyssa Milburn <alyssa.milburn@linux.intel.com>,
        Jann Horn <jannh@google.com>, "H.J. Lu" <hjl.tools@gmail.com>,
        Joao Moreira <joao.moreira@intel.com>,
        Joseph Nuzman <joseph.nuzman@intel.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Juergen Gross <jgross@suse.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Eric Dumazet <edumazet@google.com>
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On Mon, Sep 5, 2022 at 6:07 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Fri, Sep 02, 2022 at 11:08:54AM -0700, Linus Torvalds wrote:
>
> > Let's just do this right.
>
> Something like so then?

Sorry, I dropped this due to travel.

The patch looks sane, the only thing I worry a bit about is

> +config FUNCTION_ALIGNMENT
> +       int
> +       default 64 if FUNCTION_ALIGNMENT_64B
..
> +       default 0

Is '0' even a valid value then for things like

> +#define __ALIGN                        .balign CONFIG_FUNCTION_ALIGNMENT
> +#define __ALIGN_STR            __stringify(__ALIGN)

because it doesn't really seem like a sensible byte alignment.

Maybe "default 4" would be a safer choice?

                   Linus