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Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V . Shankar" , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, Yu-cheng Yu Subject: Re: [PATCH v2 04/39] x86/cpufeatures: Enable CET CR4 bit for shadow stack Message-ID: References: <20220929222936.14584-1-rick.p.edgecombe@intel.com> <20220929222936.14584-5-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220929222936.14584-5-rick.p.edgecombe@intel.com> ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665767581; a=rsa-sha256; cv=none; b=CxSj+Jzauqs1cSiU/GBKuH1CCB8Utq5dwMXelksZ/qnvlZgwSzZWPdeHiHmDgZ2fdGPZ/H ZRZztnZ+nuTMAjPDIzGNJoGJaZvTBve1wcssO/FiMNIVDoohpmakBwt3Xuk2bUGTDXF+Ky /KuSLYk6B+u7GwdQmjUZwHtaN08D0is= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=temperror ("DNS error when getting key") header.d=alien8.de header.s=dkim header.b=b22IDJ7V; spf=temperror (imf15.hostedemail.com: error in processing during lookup of bp@alien8.de: DNS error) smtp.mailfrom=bp@alien8.de; dmarc=temperror reason="server fail" header.from=alien8.de (policy=temperror) ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665767581; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+EYBcfkVNy99Prgg508di+96dEqLLAK9qFDJ8Xcfxdg=; b=vZGnO30QvAd4NupRXivrIPim/KknFA4u4wWXx1zQPz4Ybm5vaaB1acFLd1G+Rji1yRqU7Y 1zQO+yb7kKE2+8rAFRPj7T4vs6V9hxC7aHo72+9ph6ru01xDjUg1D2pPdBXjF/xKQJAyyg S/u0v+4bE4OS+5VbLc+ixlx9u4NuXfM= X-Stat-Signature: zrrckbki8yf776qjnrjbc61h38s3kkck X-Rspamd-Queue-Id: 5E9D9A002D X-Rspam-User: Authentication-Results: imf15.hostedemail.com; dkim=temperror ("DNS error when getting key") header.d=alien8.de header.s=dkim header.b=b22IDJ7V; spf=temperror (imf15.hostedemail.com: error in processing during lookup of bp@alien8.de: DNS error) smtp.mailfrom=bp@alien8.de; dmarc=temperror reason="server fail" header.from=alien8.de (policy=temperror) X-Rspamd-Server: rspam06 X-HE-Tag: 1665767576-519428 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Sep 29, 2022 at 03:29:01PM -0700, Rick Edgecombe wrote: > static __always_inline void setup_cet(struct cpuinfo_x86 *c) > { > - u64 msr = CET_ENDBR_EN; > + bool kernel_ibt = HAS_KERNEL_IBT && cpu_feature_enabled(X86_FEATURE_IBT); So I'd love it if we can get rid of that HAS_KERNEL_IBT thing and use the usual ifdeffery with Kconfig symbols. I wouldn't like for yet another HAS_XXX feature checking method to proliferate as this is the only one: $ git grep -E "\WHAS_" arch/x86/ arch/x86/include/asm/ibt.h:18: * When all the above are satisfied, HAS_KERNEL_IBT will be 1, otherwise 0. arch/x86/include/asm/ibt.h:22:#define HAS_KERNEL_IBT 1 arch/x86/include/asm/ibt.h:92:#define HAS_KERNEL_IBT 0 arch/x86/include/asm/ibt.h:114:#define ENDBR_INSN_SIZE (4*HAS_KERNEL_IBT) arch/x86/include/asm/idtentry.h:8:#define IDT_ALIGN (8 * (1 + HAS_KERNEL_IBT)) arch/x86/kernel/cpu/common.c:601: bool kernel_ibt = HAS_KERNEL_IBT && cpu_feature_enabled(X86_FEATURE_IBT); arch/x86/kernel/cpu/common.c:1942: if (HAS_KERNEL_IBT && cpu_feature_enabled(X86_FEATURE_IBT)) > __noendbr void cet_disable(void) > { > - if (cpu_feature_enabled(X86_FEATURE_IBT)) > - wrmsrl(MSR_IA32_S_CET, 0); > + if (!(cpu_feature_enabled(X86_FEATURE_IBT) || > + cpu_feature_enabled(X86_FEATURE_SHSTK))) > + return; > + > + wrmsrl(MSR_IA32_S_CET, 0); > + wrmsrl(MSR_IA32_U_CET, 0); > } > > + Stray newline. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette