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Date:   Fri, 2 Sep 2022 19:32:27 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Linus Torvalds <torvalds@linux-foundation.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>
Subject: Re: [PATCH v2 08/59] x86/build: Ensure proper function alignment
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References: <20220902130625.217071627@infradead.org>
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 <CAHk-=whdvPcHmH5eG+FUrbQw1e-05n__EWobMqbxcCTP7dtZAg@mail.gmail.com>
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On Fri, Sep 02, 2022 at 09:51:17AM -0700, Linus Torvalds wrote:
> On Fri, Sep 2, 2022 at 6:55 AM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > --- a/arch/x86/include/asm/linkage.h
> > +++ b/arch/x86/include/asm/linkage.h
> > @@ -14,9 +14,10 @@
> >
> >  #ifdef __ASSEMBLY__
> >
> > -#if defined(CONFIG_X86_64) || defined(CONFIG_X86_ALIGNMENT_16)
> > -#define __ALIGN                .p2align 4, 0x90
> > -#define __ALIGN_STR    __stringify(__ALIGN)
> > +#if CONFIG_FUNCTION_ALIGNMENT == 16
> > +#define __ALIGN                        .p2align 4, 0x90
> > +#define __ALIGN_STR            __stringify(__ALIGN)
> > +#define FUNCTION_ALIGNMENT     16
> >  #endif
> 
> Ugh.
> 
> Why is this conditional on that alignment being 16?

There is a DEBUG case that increases the thing to 32.