Date: Mon, 15 Jan 2018 09:46:11 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com,
        Catalin Marinas <catalin.marinas@arm.com>,
        X86 ML <x86@kernel.org>, Will Deacon <will.deacon@arm.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Russell King <linux@armlinux.org.uk>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alan Cox <alan@linux.intel.com>
Subject: Re: [PATCH v2 06/19] asm-generic/barrier: mask speculative execution
 flows
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On Fri, Jan 12, 2018 at 04:41:37PM -0800, Dan Williams wrote:
> This certainly needs a Kconfig "depends on JUMP_LABEL" to turn on the
> dynamic switching at all, and a HAVE_JUMP_LABEL compile time failure
> if the compiler lacks support.

We're ready to drop all compilers that don't support asm-goto on the
floor for x86. So don't over engineer it just to avoid that.