linux-kernel - Re: [PATCH v2 07/10] x86/jump_label: Implement arch_static

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Message-ID: <20180118133322.ep66qnyedjl6qeiv@pd.tnic>
Date:   Thu, 18 Jan 2018 14:33:22 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        linux-kernel@...r.kernel.org, Dave Hansen <dave.hansen@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jun Nakajima <jun.nakajima@...el.com>,
        Asit Mallick <asit.k.mallick@...el.com>
Subject: Re: [PATCH v2 07/10] x86/jump_label: Implement arch_static_assert()

On Tue, Jan 16, 2018 at 03:28:32PM +0100, Peter Zijlstra wrote:
> Implement the static (branch) assertion. It simply emits the address
> of the next instruction into a special section which objtool will read
> and validate against either __jump_table or .altinstructions.
> 
> Use like:
> 
> 	if (static_branch_likely(_key)) {
> 		arch_static_assert();
> 		/* do stuff */
> 	}
> 
> Or
> 
> 	if (static_cpu_has(_feat)) {
> 		arch_static_assert();

It looks to me like the asserts can be moved into the macros and the
assertion checking can happen by default ...?

-- 
Regards/Gruss,
    Boris.

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