From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f172.google.com (mail-pl1-f172.google.com [209.85.214.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 027FD2F25 for ; Sat, 14 May 2022 21:56:51 +0000 (UTC) Received: by mail-pl1-f172.google.com with SMTP id n18so11114132plg.5 for ; Sat, 14 May 2022 14:56:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=t9B0ELg8h6PY+Vl2TDucjtXSCma3zXaus6HyZVuhPIE=; b=W1eubUSb/5LGT0PX48eWAAjFP3e+45qNMMJH5elMun/Sun50qtQzJU6DnSdp6Eg/+a sZUGxqEPzvzsqRpYUlnPpUwqsnDjU3f8F0t6paJwsZDv37wZBcBScTKMeytTqcg+gQ85 fq0u+JX10bVU5Nl4qNuwnXTR65D2Gmk7mjZv4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=t9B0ELg8h6PY+Vl2TDucjtXSCma3zXaus6HyZVuhPIE=; b=UzEc79j8AjgmtnYhq+y/+BW9R9AHQWOyNxKvlH84T77p76qCcgLZr+RqrnT3keHhho DiLaIe0k/hNWGEZypRSPn4/z8Jg2JRc5CwJ5cWE4MfVZ2MdgDyEM+589tIqWbQ+XqCMv K6kmwngwufHPXDLXEgGxjve8EXMULoY41pKWBpFR/+xUwfqSw3LVb14s3Gd7JB9wAEH2 1rXHMrmB3b/9niH2ht/e9D6jQJ2usvY7pJz6KeLu/Rt1MqzawL9qBmtWjbja52Fjf4QL NUuMvRGTQ0VthNLFKN5CJ7hWLGyWtteUwc1J2MSVCSRGtoEiBOkhzoVDxmQoZZU/8nNR 5AaQ== X-Gm-Message-State: AOAM533SXSOs6O6h8Gr9UFnJ1GRDOI7eieRKGauMUdseWVtaJ8ol2MsE 8JcyYe2HYv8teHdASBH+AMOsHP6Sovcdxw== X-Google-Smtp-Source: ABdhPJxYql9CKgnQAH/6nysRco+nTc9rw86pT4JEKLv1mVouDl0G3T6mTm3JsTqv8m6tl1+a5OAhsw== X-Received: by 2002:a17:90b:4f81:b0:1dc:69a0:432b with SMTP id qe1-20020a17090b4f8100b001dc69a0432bmr22733023pjb.203.1652565411533; Sat, 14 May 2022 14:56:51 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id s16-20020a63f050000000b003c14af5060fsm3886055pgj.39.2022.05.14.14.56.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 May 2022 14:56:51 -0700 (PDT) Date: Sat, 14 May 2022 14:56:50 -0700 From: Kees Cook To: Sami Tolvanen Cc: linux-kernel@vger.kernel.org, Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Catalin Marinas , Will Deacon , Mark Rutland , Nathan Chancellor , Nick Desaulniers , Joao Moreira , Sedat Dilek , Steven Rostedt , linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev Subject: Re: [RFC PATCH v2 15/21] objtool: Don't warn about __cfi_ preambles falling through Message-ID: <202205141456.72950C77B@keescook> References: <20220513202159.1550547-1-samitolvanen@google.com> <20220513202159.1550547-16-samitolvanen@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220513202159.1550547-16-samitolvanen@google.com> On Fri, May 13, 2022 at 01:21:53PM -0700, Sami Tolvanen wrote: > The __cfi_ preambles contain valid instructions, which embed KCFI > type information in the following format: > > __cfi_function: > int3 > int3 > mov , %eax > int3 > int3 > function: > ... > > While the preambles are STT_FUNC and contain valid instructions, > they are not executed and always fall through. Skip the warning for > them. > > Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook -- Kees Cook