Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 28 Jun 2018 10:31:07 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        x86@kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
        Steven Rostedt <rostedt@goodmis.org>, namit@vmware.com
Subject: Re: [PATCH 5/5] x86/kernel: jump_table: use relative references
Message-ID: <20180628083107.GY2494@hirez.programming.kicks-ass.net>
References: <20180627160604.8154-1-ard.biesheuvel@linaro.org>
 <20180627160604.8154-6-ard.biesheuvel@linaro.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180627160604.8154-6-ard.biesheuvel@linaro.org>
User-Agent: Mutt/1.10.0 (2018-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Jun 27, 2018 at 06:06:04PM +0200, Ard Biesheuvel wrote:
> Similar to the arm64 case, 64-bit x86 can benefit from using 32-bit
> relative references rather than 64-bit absolute ones when emitting
> struct jump_entry instances. Not only does this reduce the memory
> footprint of the entries themselves by 50%, it also removes the need
> for carrying relocation metadata on relocatable builds (i.e., for KASLR)
> which saves a fair chunk of .init space as well (although the savings
> are not as dramatic as on arm64)

This will conflict with:

  https://lkml.kernel.org/r/20180622172212.199633-10-namit@vmware.com