From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 160A2C41514 for ; Thu, 5 Sep 2019 11:33:03 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DB96722CF5 for ; Thu, 5 Sep 2019 11:33:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="fQ2pxKWh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB96722CF5 Authentication-Results: mail.kernel.org; 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Thu, 5 Sep 2019 11:32:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567683149; bh=Y+myvtaL/wVtidX/HGF2iJ5MxtkmherpGfkJw9XyNpI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=fQ2pxKWhksD2CMPVfQNcHYobKtpPfkh2PKa4YujwIMyaCVYwLoqBvhennaA8SVflm R9qs0Vv7rIyRfbig0j3hXq/kINB3MvWzLvOzxi68MnM/ekvP7JK/QJJ7LLKSiIBvt5 2XV21+pxjeh1LIhtWyY4qv3ZlRFs2OtjL6I20LdA= Date: Thu, 5 Sep 2019 20:32:24 +0900 From: Masami Hiramatsu To: Andrew Cooper Message-Id: <20190905203224.e41d7f3dfbf918c5031f9766@kernel.org> In-Reply-To: <1372ce73-e2d8-6144-57df-a98429587826@citrix.com> References: <156759754770.24473.11832897710080799131.stgit@devnote2> <20190905104937.60aa03f699a9c0fbf1b651b9@kernel.org> <1372ce73-e2d8-6144-57df-a98429587826@citrix.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Subject: Re: [Xen-devel] [PATCH -tip 0/2] x86: Prohibit kprobes on XEN_EMULATE_PREFIX X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Stefano Stabellini , Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org, Borislav Petkov , Randy Dunlap , Josh Poimboeuf , xen-devel@lists.xenproject.org, Boris Ostrovsky , Ingo Molnar Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" T24gVGh1LCA1IFNlcCAyMDE5IDA4OjU0OjE3ICswMTAwCkFuZHJldyBDb29wZXIgPGFuZHJldy5j b29wZXIzQGNpdHJpeC5jb20+IHdyb3RlOgoKPiBPbiAwNS8wOS8yMDE5IDAyOjQ5LCBNYXNhbWkg SGlyYW1hdHN1IHdyb3RlOgo+ID4gT24gV2VkLCA0IFNlcCAyMDE5IDEyOjU0OjU1ICswMTAwCj4g PiBBbmRyZXcgQ29vcGVyIDxhbmRyZXcuY29vcGVyM0BjaXRyaXguY29tPiB3cm90ZToKPiA+Cj4g Pj4gT24gMDQvMDkvMjAxOSAxMjo0NSwgTWFzYW1pIEhpcmFtYXRzdSB3cm90ZToKPiA+Pj4gSGks Cj4gPj4+Cj4gPj4+IFRoZXNlIHBhdGNoZXMgYWxsb3cgeDg2IGluc3RydWN0aW9uIGRlY29kZXIg dG8gZGVjb2RlCj4gPj4+IHhlbi1jcHVpZCB3aGljaCBoYXMgWEVOX0VNVUxBVEVfUFJFRklYLCBh bmQgcHJvaGliaXQKPiA+Pj4ga3Byb2JlcyB0byBwcm9iZSBvbiBpdC4KPiA+Pj4KPiA+Pj4gSm9z aCByZXBvcnRlZCB0aGF0IHRoZSBvYmp0b29sIGNhbiBub3QgZGVjb2RlIHN1Y2ggc3BlY2lhbAo+ ID4+PiBwcmVmaXhlZCBpbnN0cnVjdGlvbnMsIGFuZCBJIGZvdW5kIHRoYXQgd2UgYWxzbyBoYXZl IHRvCj4gPj4+IHByb2hpYml0IGtwcm9iZXMgdG8gcHJvYmUgb24gc3VjaCBpbnN0cnVjdGlvbi4K PiA+Pj4KPiA+Pj4gVGhpcyBzZXJpZXMgY2FuIGJlIGFwcGxpZWQgb24gLXRpcCBtYXN0ZXIgYnJh bmNoIHdoaWNoCj4gPj4+IGhhcyBtZXJnZWQgSm9zaCdzIG9ianRvb2wvcGVyZiBzaGFyaW5nIGNv bW1vbiB4ODYgaW5zbgo+ID4+PiBkZWNvZGVyIHNlcmllcy4KPiA+PiBUaGUgcGFyYXZpcnR1YWxp c2VkIHhlbi1jcHVpZCBpcyB3ZXJlIHlvdSdsbCBzZWUgaXQgbW9zdCBpbiBhIHJlZ3VsYXIKPiA+ PiBrZXJuZWwsIGJ1dCBiZSBhd2FyZSB0aGF0IGl0IGlzIGFsc28gdXNlZCBmb3IgdGVzdGluZyBw dXJwb3NlcyBpbiBvdGhlcgo+ID4+IGNpcmN1bXN0YW5jZXMsIGFuZCB0aGVyZSBpcyBhbiBlcXVp dmFsZW50IEtWTSBwcmVmaXggd2hpY2ggaXMgdXNlZCBmb3IKPiA+PiBLVk0gdGVzdGluZy4KPiA+ IEdvb2QgY2F0Y2ghIEkgZGlkbid0IG5vdGljZSB0aGF0LiBJcyB0aGF0IHJlYWxseSBzYW1lIHNl cXVhbmNlIG9yIEtWTSB1c2VzCj4gPiBhbm90aGVyIHNlcXVlbmNlIG9mIGluc3RydWN0aW9ucyBm b3IgS1ZNIHByZWZpeD8KPiAKPiBJIGRvbid0IGtub3cgaWYgeW91J3ZlIHNwb3R0ZWQsIGJ1dCB0 aGUgcHJlZml4IGlzIGEgdWQyYSBpbnN0cnVjdGlvbgo+IGZvbGxvd2VkIGJ5ICd4ZW4nIGluIGFz Y2lpLgo+IAo+IFRoZSBLVk0gdmVyc2lvbiB3YXMgYWRkZWQgaW4gYy9zIDZjODZlZWRjMjA2ZGQx ZjlkMzdhMjc5NmZhYThlNmYyMjc4MjE1ZDIKPiAKCkFoLCBPSy4gSSBzZWUgaXQuIEJ1dCBpdCBz ZWVtcyB0aGF0IGFub3RoZXIgdWQwL3VkMSBjYW4gYmUgdXNlZCBieQpvdGhlciAobmV3KSB2aXJ0 dWFsaXphdGlvbi4gU28gYXQgdGhpcyBtb21lbnQgSSB3aWxsIGp1c3QgYWRkIGEgc2VxdWVuY2UK YXMgYSBwYXR0ZXJuIG9mIHByZWZpeC4gTm90IHVzZSBhIGZpeGVkIHVkMiArIHNpZy4KClRoYW5r IHlvdSwKCj4gPgo+ID4+IEl0IG1pZ2h0IGJlIGJldHRlciB0byBnZW5lcmFsaXNlIHRoZSBkZWNv ZGUgc3VwcG9ydCB0byAidmlydHVhbGlzYXRpb24KPiA+PiBlc2NhcGUgcHJlZml4IiBvciBzb21l dGhpbmcgc2xpZ2h0bHkgbW9yZSBnZW5lcmljLgo+ID4gQWdyZWVkLCBpdCBpcyBlYXN5IHRvIGV4 cGFuZCBpdCwgd2UgY2FuIHN3aXRjaCB0aGUgcHJlZml4IHRlbXBsYXRlLgo+ID4gQ291bGQgeW91 IHRlbGwgbWUgd2hlcmUgSSBzaG91bGQgbG9vaz8gSSB3aWxsIGFkZCBpdC4KPiAKPiBUaGVzZSBh cmUgdGhlIG9ubHkgdHdvIEknbSBhd2FyZSBvZi4KCgoKPiAKPiB+QW5kcmV3CgoKLS0gCk1hc2Ft aSBIaXJhbWF0c3UgPG1oaXJhbWF0QGtlcm5lbC5vcmc+CgpfX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fXwpYZW4tZGV2ZWwgbWFpbGluZyBsaXN0Clhlbi1kZXZl bEBsaXN0cy54ZW5wcm9qZWN0Lm9yZwpodHRwczovL2xpc3RzLnhlbnByb2plY3Qub3JnL21haWxt YW4vbGlzdGluZm8veGVuLWRldmVs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD9C6C3A5A5 for ; 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Thu, 5 Sep 2019 11:32:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567683149; bh=Y+myvtaL/wVtidX/HGF2iJ5MxtkmherpGfkJw9XyNpI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=fQ2pxKWhksD2CMPVfQNcHYobKtpPfkh2PKa4YujwIMyaCVYwLoqBvhennaA8SVflm R9qs0Vv7rIyRfbig0j3hXq/kINB3MvWzLvOzxi68MnM/ekvP7JK/QJJ7LLKSiIBvt5 2XV21+pxjeh1LIhtWyY4qv3ZlRFs2OtjL6I20LdA= Date: Thu, 5 Sep 2019 20:32:24 +0900 From: Masami Hiramatsu To: Andrew Cooper Cc: Ingo Molnar , Juergen Gross , "Stefano Stabellini" , Peter Zijlstra , Randy Dunlap , , , Borislav Petkov , "Josh Poimboeuf" , , "Boris Ostrovsky" Subject: Re: [Xen-devel] [PATCH -tip 0/2] x86: Prohibit kprobes on XEN_EMULATE_PREFIX Message-Id: <20190905203224.e41d7f3dfbf918c5031f9766@kernel.org> In-Reply-To: <1372ce73-e2d8-6144-57df-a98429587826@citrix.com> References: <156759754770.24473.11832897710080799131.stgit@devnote2> <20190905104937.60aa03f699a9c0fbf1b651b9@kernel.org> <1372ce73-e2d8-6144-57df-a98429587826@citrix.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 5 Sep 2019 08:54:17 +0100 Andrew Cooper wrote: > On 05/09/2019 02:49, Masami Hiramatsu wrote: > > On Wed, 4 Sep 2019 12:54:55 +0100 > > Andrew Cooper wrote: > > > >> On 04/09/2019 12:45, Masami Hiramatsu wrote: > >>> Hi, > >>> > >>> These patches allow x86 instruction decoder to decode > >>> xen-cpuid which has XEN_EMULATE_PREFIX, and prohibit > >>> kprobes to probe on it. > >>> > >>> Josh reported that the objtool can not decode such special > >>> prefixed instructions, and I found that we also have to > >>> prohibit kprobes to probe on such instruction. > >>> > >>> This series can be applied on -tip master branch which > >>> has merged Josh's objtool/perf sharing common x86 insn > >>> decoder series. > >> The paravirtualised xen-cpuid is were you'll see it most in a regular > >> kernel, but be aware that it is also used for testing purposes in other > >> circumstances, and there is an equivalent KVM prefix which is used for > >> KVM testing. > > Good catch! I didn't notice that. Is that really same sequance or KVM uses > > another sequence of instructions for KVM prefix? > > I don't know if you've spotted, but the prefix is a ud2a instruction > followed by 'xen' in ascii. > > The KVM version was added in c/s 6c86eedc206dd1f9d37a2796faa8e6f2278215d2 > Ah, OK. I see it. But it seems that another ud0/ud1 can be used by other (new) virtualization. So at this moment I will just add a sequence as a pattern of prefix. Not use a fixed ud2 + sig. Thank you, > > > >> It might be better to generalise the decode support to "virtualisation > >> escape prefix" or something slightly more generic. > > Agreed, it is easy to expand it, we can switch the prefix template. > > Could you tell me where I should look? I will add it. > > These are the only two I'm aware of. > > ~Andrew -- Masami Hiramatsu