linux-kernel - Re: [tip:x86/boot] x86/kaslr, ACPI/NUMA: Fix KASLR build error

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Date:   Mon, 8 Oct 2018 15:48:28 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Borislav Petkov <bp@...e.de>
Cc:     Naresh Kamboju <naresh.kamboju@...aro.org>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>, m.mizuma@...fujitsu.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Baoquan He <bhe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-tip-commits@...r.kernel.org, lkft-triage@...ts.linaro.org
Subject: Re: [tip:x86/boot] x86/kaslr, ACPI/NUMA: Fix KASLR build error

On Mon, Oct 8, 2018 at 3:01 PM Borislav Petkov <bp@...e.de> wrote:
>
> On Mon, Oct 08, 2018 at 04:33:29PM +0530, Naresh Kamboju wrote:
> > Linux next build for arm64 failed due to
> > numa.c:34:10: fatal error: asm/kaslr.h: No such file or directory
>
> Thanks for letting me know, I guess we could fix that with a weak
> function:
>

> +/* To be overridden by architectures */
> +void __init __weak kaslr_check_padding(void) { }
> +
>  int __init acpi_numa_init(void)
>  {
>         int cnt = 0;
>

I think __weak functions are too fragile, when you do this and it
turns out that another architecture does need to do something,
you won't ever get any indication of it.

If we know that arm64 doesn't need to do anything here, just
add an arch/arm64/include/asm/kaslr.h with an empty function
there.

      Arnd