linux-kernel - Re: [PATCH v6 9/9] x86: jump-labels: use macros instead of inline assembly

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Message-ID: <20180724142647.GA31700@gmail.com>
Date:   Tue, 24 Jul 2018 16:26:47 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Nadav Amit <namit@...are.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Philippe Ombredanne <pombredanne@...b.com>
Subject: Re: [PATCH v6 9/9] x86: jump-labels: use macros instead of inline
 assembly


* Nadav Amit <namit@...are.com> wrote:

> Use assembly macros for jump-labels and call them from inline assembly.
> This not only makes the code more readable, but also improves
> compilation decision, specifically inline decisions which GCC base on
> the number of new lines in inline assembly.
> 
> As a result the code size is slightly increased.
> 
>    text	   data	    bss	    dec	    hex	filename
> 18163528 10226300 2957312 31347140 1de51c4 ./vmlinux before
> 18163608 10227348 2957312 31348268 1de562c ./vmlinux after (+1128)
> 
> And functions such as intel_pstate_adjust_policy_max(),
> kvm_cpu_accept_dm_intr(), kvm_register_readl() are inlined.
> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: x86@...nel.org
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Kate Stewart <kstewart@...uxfoundation.org>
> Cc: Philippe Ombredanne <pombredanne@...b.com>
> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Signed-off-by: Nadav Amit <namit@...are.com>
> ---
>  arch/x86/entry/calling.h          |  2 +-
>  arch/x86/include/asm/jump_label.h | 77 +++++++++++--------------------
>  arch/x86/kernel/macros.S          |  1 +
>  3 files changed, 30 insertions(+), 50 deletions(-)

So I tried the series, and this patch causes a silent hard hang on bootup, with no 
(early-)console messages visible.

I've attached the config that triggers the problem, built with:

  gcc version 5.3.1 20160406 (Red Hat 5.3.1-6) (GCC) 

it's 100% reproducible on both Intel and AMD test systems.

I'll continue to test the series with this patch left out.

So both the xtensa build failure and this boot failure needs to be fixed before I 
can apply this series.

Thanks,

	Ingo