Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
Date:   Fri, 4 Mar 2022 10:02:19 -0800
From:   Josh Poimboeuf <jpoimboe@redhat.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com,
        andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org,
        ndesaulniers@google.com, keescook@chromium.org,
        samitolvanen@google.com, mark.rutland@arm.com,
        alyssa.milburn@intel.com, mbenes@suse.cz, rostedt@goodmis.org,
        mhiramat@kernel.org, alexei.starovoitov@gmail.com
Subject: Re: [PATCH v3 23/39] x86/alternative: Simplify int3_selftest_ip
Message-ID: <20220304180219.hiyg2e6e6z76mfjz@treble>
References: <20220303112321.422525803@infradead.org>
 <20220303112826.360149715@infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20220303112826.360149715@infradead.org>
Precedence: bulk

On Thu, Mar 03, 2022 at 12:23:44PM +0100, Peter Zijlstra wrote:
> @@ -733,7 +733,7 @@ int3_exception_notify(struct notifier_bl
>  	if (val != DIE_INT3)
>  		return NOTIFY_DONE;
>  
> -	if (regs->ip - INT3_INSN_SIZE != int3_selftest_ip)
> +	if (regs->ip - INT3_INSN_SIZE != (unsigned long)&int3_selftest_ip)
>  		return NOTIFY_DONE;
>  
>  	int3_emulate_call(regs, (unsigned long)&int3_magic);
> @@ -757,14 +757,7 @@ static void __init int3_selftest(void)
>  	 * then trigger the INT3, padded with NOPs to match a CALL instruction
>  	 * length.
>  	 */
> -	asm volatile ("1: int3; nop; nop; nop; nop\n\t"
> -		      ".pushsection .init.data,\"aw\"\n\t"
> -		      ".align " __ASM_SEL(4, 8) "\n\t"
> -		      ".type int3_selftest_ip, @object\n\t"
> -		      ".size int3_selftest_ip, " __ASM_SEL(4, 8) "\n\t"
> -		      "int3_selftest_ip:\n\t"
> -		      __ASM_SEL(.long, .quad) " 1b\n\t"
> -		      ".popsection\n\t"
> +	asm volatile ("int3_selftest_ip: int3; nop; nop; nop; nop\n\t"
>  		      : ASM_CALL_CONSTRAINT
>  		      : __ASM_SEL_RAW(a, D) (&val)
>  		      : "memory");

Hm, why doesn't this need ANNOTATE_NOENDBR?

-- 
Josh