linux-kernel - Re: [PATCH v3 22/39] x86/ibt: Add IBT feature, MSR and #CP handling

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Message-ID: <20220304175733.zoik2fqpizygnlq7@treble>
Date:   Fri, 4 Mar 2022 09:57:33 -0800
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, joao@...rdrivepizza.com, hjl.tools@...il.com,
        andrew.cooper3@...rix.com, linux-kernel@...r.kernel.org,
        ndesaulniers@...gle.com, keescook@...omium.org,
        samitolvanen@...gle.com, mark.rutland@....com,
        alyssa.milburn@...el.com, mbenes@...e.cz, rostedt@...dmis.org,
        mhiramat@...nel.org, alexei.starovoitov@...il.com
Subject: Re: [PATCH v3 22/39] x86/ibt: Add IBT feature, MSR and #CP handling

On Thu, Mar 03, 2022 at 12:23:43PM +0100, Peter Zijlstra wrote:
> +bool ibt_selftest(void)
> +{
> +	unsigned long ret;
> +
> +	asm ("	lea ibt_selftest_ip(%%rip), %%rax\n\t"
> +	     ANNOTATE_RETPOLINE_SAFE
> +	     "	jmp *%%rax\n\t"
> +	     ASM_REACHABLE
> +	     ANNOTATE_NOENDBR
> +	     "ibt_selftest_ip: nop\n\t"

Maybe pedantic, but I find the annotations to be less surprising if they
come after the label:

	"ibt_selftest_ip:\n\t"
	ASM_REACHABLE
	ANNOTATE_NOENDBR
	"nop\n\t"

-- 
Josh