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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DF314C47089 for ; Tue, 6 Dec 2022 00:43:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Mime-Version:References:In-Reply-To: Message-Id:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=emEh/zRehxuv3fBeJQ6Ih2Y3YFlFmzUTlIfw54oVoM8=; b=1TSu8+qHMh4MqR 26ElmdgYhdHzH7vZ5PMvmNFL20Ky1lZcSOb+ip3hMYSibgivUrkC0VvRLXkKDhXOO/7IwfEoaBFgo xYed8b+Rc/Ym1VPnsuMOSLrvJnQkCc1Hy2mmT2hnKqtHxk44LnW6sRFikSWgRtioHpAR8Nu50wZVt 9hGRsPYP5Lmnh16qK7CBU0BKD2THf9fjxOOa4t69Hrr5v/bI/PT8+ktenmZKg5kII/wbGl/w6TCwK 5V1kaMVXo00BYI3NR222IlN12fNSt8Ls9VRyNAl1f3wZNHjEK/yUSCD5hq8TB30NRzVoOkYqNvYAz iyY/yHARWM9kUxCht80Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1p2M1p-00E8o6-Da; Tue, 06 Dec 2022 00:41:45 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1p2M1m-00E8km-7r for linux-arm-kernel@lists.infradead.org; Tue, 06 Dec 2022 00:41:43 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EFF6E614F1; Tue, 6 Dec 2022 00:41:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5D46C433D7; Tue, 6 Dec 2022 00:41:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670287300; bh=PHYevn3Vh1bRzHgX8jaY2KGyymMFzZcEuYmLigdgpFY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HREFEuzQkgTBk6bZMKgFTiB8CEqWJP4JL8snfVoRvIFSkAZ+1NqBLredgeO8ut1cI BOCHfhAqHxu+dA2bgYxP72JxkG+Gy/Sb6KaWcp3aGAOaIyiFMGTIitp2hUrt2OkapU UjjZ/H0gJGeA1B5qfjLOwgoLEHrUJ9rGV8e4GsBICCkZLUqsLbhGscY9VEN+qfj3uR jcOUGDFq3BRpWgEw3W6ccjdbsGFr9S8LQVsrLgFc0+etQ/hbpIelyT4Mf4ZxXMLSvC M7DFFBwFk0gz9Zjfm9ZLS0b5J3tleD6OzTi2zgEMy56r7dlgWBo1NP5HB5ECKb3ABq DYs50wj3+Gm9A== Date: Tue, 6 Dec 2022 09:41:37 +0900 From: Masami Hiramatsu (Google) To: Mark Rutland Cc: Catalin Marinas , Will Deacon , Mark Brown , Kalesh Singh , Marc Zyngier , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sandeepa Prabhu Subject: Re: [PATCH v2 1/3] arm64: Prohibit instrumentation on arch_stack_walk() Message-Id: <20221206094137.389e4c374f4be060af19f33a@kernel.org> In-Reply-To: References: <166994750386.439920.1754385804350980158.stgit@devnote3> <166994751368.439920.3236636557520824664.stgit@devnote3> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221205_164142_379447_98831088 X-CRM114-Status: GOOD ( 41.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gRnJpLCAyIERlYyAyMDIyIDEzOjE3OjMwICswMDAwCk1hcmsgUnV0bGFuZCA8bWFyay5ydXRs YW5kQGFybS5jb20+IHdyb3RlOgoKPiBPbiBGcmksIERlYyAwMiwgMjAyMiBhdCAxMToxODozM0FN ICswOTAwLCBNYXNhbWkgSGlyYW1hdHN1IChHb29nbGUpIHdyb3RlOgo+ID4gRnJvbTogTWFzYW1p IEhpcmFtYXRzdSAoR29vZ2xlKSA8bWhpcmFtYXRAa2VybmVsLm9yZz4KPiA+IAo+ID4gTWFyayBh cmNoX3N0YWNrX3dhbGsoKSBhcyBub2luc3RyIGluc3RlYWQgb2Ygbm90cmFjZSBhbmQgaW5saW5l IGZ1bmN0aW9ucwo+ID4gY2FsbGVkIGZyb20gYXJjaF9zdGFja193YWxrKCkgYXMgX19hbHdheXNf aW5saW5lIHNvIHRoYXQgdXNlciBkb2VzIG5vdAo+ID4gcHV0IGFueSBpbnN0cnVtZW50YXRpb25z IG9uIGl0LCBiZWNhdXNlIHRoaXMgZnVuY3Rpb24gY2FuIGJlIHVzZWQgZnJvbQo+ID4gcmV0dXJu X2FkZHJlc3MoKSB3aGljaCBpcyB1c2VkIGJ5IGxvY2tkZXAuCj4gCj4gSG1tbS4uLiBzaW5jZSBh cmNoX3N0YWNrX3dhbGsgaXMgbWFya2VkIGFzIG5vdHJhY2UsIHRoYXQgd2lsbCBiZSBwcm9oaWJp dGVkIGJ5Cj4gZGVmYXVsdCB1bmxlc3MgdGhlIGtlcm5lbCB3YXMgYnVpbHQgd2l0aCBDT05GSUdf S1BST0JFX0VWRU5UU19PTl9OT1RSQUNFPXksCj4gYW5kIHRoZSBjb21taXQgbWVzc2FnZSBmb3Ig dGhhdCBzYXlzOgo+IAo+IOKUgiBUaGlzIG9wdGlvbiBkaXNhYmxlcyBzdWNoIHByb3RlY3Rpb24g YW5kIGFsbG93cyB5b3UgdG8gcHV0IGtwcm9iZSAgICAgICAgICAgICAgICAgICAgICAgICAgICAg ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg4pSCCj4g4pSCIGV2 ZW50cyBvbiBmdHJhY2UgZnVuY3Rpb25zIGZvciBkZWJ1Z2dpbmcgZnRyYWNlIGJ5IGl0c2VsZi4g ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg ICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAg ICAgICAgICAgICAgICAgICAgICAgICDilIIKPiDilIIgTm90ZSB0aGF0IHRoaXMgbWlnaHQgbGV0 IHlvdSBzaG9vdCB5b3Vyc2VsZiBpbiB0aGUgZm9vdC4KPiAKPiAuLi4gYW5kIElJVUMgd2UgZ2Vu ZXJhbGx5IGRvbid0IGV4cGVjdCBwZW9wbGUgdG8gc2V0IHRoYXQsIGFuZCB0aGF0IG1pZ2h0IGJl Cj4gd29ydGggY2FsbGluZyBvdXQgaW4gdGhlIGNvbW1pdCBtZXNzYWdlLgoKWWVhaCwgYnV0IHRo YXQgaXMgdGhlIGZlYXR1cmUgZm9yIGtwcm9iZSBldmVudHMsIGFuZCBub3QgYXBwbGllZCB0bwp0 aGUga3Byb2JlcyBpdHNlbGYuIE1heWJlIEkgc2hvdWxkIHVzZSBhIHRlc3Qga3Byb2JlIG1vZHVs ZSB0bwpwdXQgYSBwcm9iZSBvbiBpdC4KCj4gCj4gPiBXaXRob3V0IHRoaXMsIGlmIHRoZSBrZXJu ZWwgYnVpbHQgd2l0aCBDT05GSUdfTE9DS0RFUD15LCBqdXN0IHByb2JpbmcKPiA+IGFyY2hfc3Rh Y2tfd2FsaygpIHZpYSA8dHJhY2Vmcz4va3Byb2JlX2V2ZW50cyB3aWxsIGNyYXNoIHRoZSBrZXJu ZWwgb24KPiA+IGFybTY0Lgo+ID4gCj4gPiAgIyBlY2hvIHAgYXJjaF9zdGFja193YWxrID4+ICR7 VFJBQ0VGU30va3Byb2JlX2V2ZW50cwo+ID4gICMgZWNobyAxID4gJHtUUkFDRUZTfS9ldmVudHMv a3Byb2Jlcy9lbmFibGUKPiAKPiBJIGhhZCBhIGdvIGF0IHRlc3RpbmcgdGhpcyBwYXRjaCwgYW5k IGl0IGZpeGVzIHRoZSBjcmFzaCB3aXRoIHRoZSByZXByb2R1Y2VyCj4gYWJvdmUsIGJ1dCB0aGVy ZSBhcmUgcGxlbnR5IG9mIG90aGVyIGluc3RhbmNlcyBpbiBzdGFja3RyYWNlLmMgdGhhdCBsZWFk IHRvIHRoZQo+IHNhbWUgc29ydCBvZiBjcmFzaCwgZS5nLgo+IAo+ICMgZWNobyBwIHN0YWNraW5m b19nZXRfdGFzayA+PiAke1RSQUNFRlN9L2twcm9iZV9ldmVudHMKPiAjIGVjaG8gMSA+ICR7VFJB Q0VGU30vZXZlbnRzL2twcm9iZXMvZW5hYmxlCgpPb3BzLCB0aGFua3MgZm9yIHBvaW50aW5nISBI bW0sIEkgdGhvdWdodCBzdGFja2luZm9fZ2V0X3Rhc2soKSBpcyBhbgppbmxpbmVkIGZ1bmN0aW9u IHVzdWFsbHkuIE1heWJlIHdlIHNob3VsZCBtYWtlIGl0IG5va3Byb2JlX2lubGluZS4KQnV0IHRo aXMgaXMganVzdCBvbmUgY2FzZS4gSSBuZWVkIHRvIHNjYW4gYWxsIHN5bWJvbHMgdG8gdHJhY2Uu Li4KCj4gCj4gLi4uIHNvIEkgdGhpbmsgdGhlcmUncyBtb3JlIHRoYXQgd2UgbmVlZCB0byBkbyB0 byBmaXggdGhpcyBnZW5lcmFsbHkuCj4gCj4gTm90ZTogSSBmb3VuZCBpbnRlcmVzdGluZyBmdW5j dGlvbnMgdG8gdHJ5IHRyYWNpbmcgYnkgbG9va2luZyBhdCB0aGUgb3V0cHV0IG9mOgo+IAo+ICAg YWFyY2g2NC1saW51eC1vYmpkdW1wIC10IGFyY2gvYXJtNjQva2VybmVsL3N0YWNrdHJhY2UubyB8 IGdyZXAgLXcgJy50ZXh0Jwo+IAo+IFRoYXQgYWxsIHNhaWQsIEkgdGhpbmsgdGhpcyBwYXRjaCBp cyBuaWNlLXRvLWhhdmUsIGFuZCB0aGF0IHdlIGNhbiBhZGRyZXNzIHRoZQo+IG90aGVyIGNhc2Vz IGFzIGEgZm9sbG93LXVwLCBzbyBmb3IgdGhpcyBwYXRjaCBhcy1pcyAod2l0aCBvciB3aXRob3V0 IHNvbWUKPiB3b3JkaW5nIHJlZ2FyZGluZyBDT05GSUdfS1BST0JFX0VWRU5UU19PTl9OT1RSQUNF KToKPiAKPiBBY2tlZC1ieTogTWFyayBSdXRsYW5kIDxtYXJrLnJ1dGxhbmRAYXJtLmNvbT4KClRo YW5rcyEKCj4gCj4gTWFyay4KPiAKPiA+ICAga3Byb2JlczogRmFpbGVkIHRvIHJlY292ZXIgZnJv bSByZWVudGVyZWQga3Byb2Jlcy4KPiA+ICAga3Byb2JlczogRHVtcCBrcHJvYmU6Cj4gPiAgIC5z eW1ib2xfbmFtZSA9IGFyY2hfc3RhY2tfd2FsaywgLm9mZnNldCA9IDAsIC5hZGRyID0gYXJjaF9z dGFja193YWxrKzB4MC8weDFjMAo+ID4gICAtLS0tLS0tLS0tLS1bIGN1dCBoZXJlIF0tLS0tLS0t LS0tLS0KPiA+ICAga2VybmVsIEJVRyBhdCBhcmNoL2FybTY0L2tlcm5lbC9wcm9iZXMva3Byb2Jl cy5jOjI0MSEKPiA+ICAga3Byb2JlczogRmFpbGVkIHRvIHJlY292ZXIgZnJvbSByZWVudGVyZWQg a3Byb2Jlcy4KPiA+ICAga3Byb2JlczogRHVtcCBrcHJvYmU6Cj4gPiAgIC5zeW1ib2xfbmFtZSA9 IGFyY2hfc3RhY2tfd2FsaywgLm9mZnNldCA9IDAsIC5hZGRyID0gYXJjaF9zdGFja193YWxrKzB4 MC8weDFjMAo+ID4gICAtLS0tLS0tLS0tLS1bIGN1dCBoZXJlIF0tLS0tLS0tLS0tLS0KPiA+ICAg a2VybmVsIEJVRyBhdCBhcmNoL2FybTY0L2tlcm5lbC9wcm9iZXMva3Byb2Jlcy5jOjI0MSEKPiA+ ICAgUFJFRU1QVCBTTVAKPiA+ICAgTW9kdWxlcyBsaW5rZWQgaW46Cj4gPiAgIENQVTogMCBQSUQ6 IDE3IENvbW06IG1pZ3JhdGlvbi8wIFRhaW50ZWQ6IEcgICAgICAgICAgICAgICAgIE4gNi4xLjAt cmM1KyAjNgo+ID4gICBIYXJkd2FyZSBuYW1lOiBsaW51eCxkdW1teS12aXJ0IChEVCkKPiA+ICAg U3RvcHBlcjogMHgwIDwtIDB4MAo+ID4gICBwc3RhdGU6IDYwMDAwM2M1IChuWkN2IERBSUYgLVBB TiAtVUFPIC1UQ08gLURJVCAtU1NCUyBCVFlQRT0tLSkKPiA+ICAgcGMgOiBrcHJvYmVfYnJlYWtw b2ludF9oYW5kbGVyKzB4MTc4LzB4MTdjCj4gPiAgIGxyIDoga3Byb2JlX2JyZWFrcG9pbnRfaGFu ZGxlcisweDE3OC8weDE3Ywo+ID4gICBzcCA6IGZmZmY4MDAwMDgwZDMwOTAKPiA+ICAgeDI5OiBm ZmZmODAwMDA4MGQzMDkwIHgyODogZmZmZjBkZjU4NDU3OThjMCB4Mjc6IGZmZmZjNGY1OTA1N2E3 NzQKPiA+ICAgeDI2OiBmZmZmMGRmNWZmYmJhNzcwIHgyNTogZmZmZjBkZjU4ZjQyMGYxOCB4MjQ6 IGZmZmY0OTAwNmY2NDEwMDAKPiA+ICAgeDIzOiBmZmZmYzRmNTkwNTc5NzY4IHgyMjogZmZmZjBk ZjU4ZjQyMGYxOCB4MjE6IGZmZmY4MDAwMDgwZDMxYzAKPiA+ICAgeDIwOiBmZmZmYzRmNTkwNTc5 NzY4IHgxOTogZmZmZmM0ZjU5MDU3OTc3MCB4MTg6IDAwMDAwMDAwMDAwMDAwMDYKPiA+ICAgeDE3 OiA1ZjZiNjM2MTc0NzM1ZjY4IHgxNjogNjM3MjYxMjAzZDIwNzI2NCB4MTU6IDY0NjEyZTIwMmMz MDIwM2QKPiA+ICAgeDE0OiAyMDc0NjU3MzY2NjY2ZjJlIHgxMzogMzA2MzMxNzgzMDJmMzA3OCB4 MTI6IDMwMmI2YjZjNjE3NzVmNmIKPiA+ICAgeDExOiA2MzYxNzQ3MzVmNjg2MzcyIHgxMDogZmZm ZmM0ZjU5MGRjNWJkOCB4OSA6IGZmZmZjNGY1OGViMzE5NTgKPiA+ICAgeDggOiAwMDAwMDAwMGZm ZmZlZmZmIHg3IDogZmZmZmM0ZjU5MGRjNWJkOCB4NiA6IDgwMDAwMDAwZmZmZmYwMDAKPiA+ICAg eDUgOiAwMDAwMDAwMDAwMDBiZmY0IHg0IDogMDAwMDAwMDAwMDAwMDAwMCB4MyA6IDAwMDAwMDAw MDAwMDAwMDAKPiA+ICAgeDIgOiAwMDAwMDAwMDAwMDAwMDAwIHgxIDogZmZmZjBkZjU4NDU3OThj MCB4MCA6IDAwMDAwMDAwMDAwMDAwNjQKPiA+ICAgQ2FsbCB0cmFjZToKPiA+ICAga3Byb2Jlczog RmFpbGVkIHRvIHJlY292ZXIgZnJvbSByZWVudGVyZWQga3Byb2Jlcy4KPiA+ICAga3Byb2Jlczog RHVtcCBrcHJvYmU6Cj4gPiAgIC5zeW1ib2xfbmFtZSA9IGFyY2hfc3RhY2tfd2FsaywgLm9mZnNl dCA9IDAsIC5hZGRyID0gYXJjaF9zdGFja193YWxrKzB4MC8weDFjMAo+ID4gICAtLS0tLS0tLS0t LS1bIGN1dCBoZXJlIF0tLS0tLS0tLS0tLS0KPiA+ICAga2VybmVsIEJVRyBhdCBhcmNoL2FybTY0 L2tlcm5lbC9wcm9iZXMva3Byb2Jlcy5jOjI0MSEKPiA+IAo+ID4gRml4ZXM6IDM5ZWYzNjJkMmQ0 NSAoImFybTY0OiBNYWtlIHJldHVybl9hZGRyZXNzKCkgdXNlIGFyY2hfc3RhY2tfd2FsaygpIikK PiA+IENjOiBzdGFibGVAdmdlci5rZXJuZWwub3JnCj4gPiBTaWduZWQtb2ZmLWJ5OiBNYXNhbWkg SGlyYW1hdHN1IChHb29nbGUpIDxtaGlyYW1hdEBrZXJuZWwub3JnPgo+ID4gLS0tCj4gPiAgQ2hh bmdlcyBpbiB2MjoKPiA+ICAgLSBVc2Ugbm9pbnN0ciBpbnN0ZWFkIG9mIE5PS1BST0JFX1NZTUJP TCgpCj4gPiAgIC0gVXNlIF9fYWx3YXlzX2lubGluZSBiZWNhdXNlIG5va3Byb2JlX2lubGluZSB3 aWxsIGJlIGNoYW5nZWQgaWYKPiA+ICAgICBDT05GSUdfS1BST0JFUz1uLgo+ID4gICAtIEZpeCBp bmRlbnRhdGlvbi4KPiA+IC0tLQo+ID4gIGFyY2gvYXJtNjQva2VybmVsL3N0YWNrdHJhY2UuYyB8 ICAgMTAgKysrKystLS0tLQo+ID4gIDEgZmlsZSBjaGFuZ2VkLCA1IGluc2VydGlvbnMoKyksIDUg ZGVsZXRpb25zKC0pCj4gPiAKPiA+IGRpZmYgLS1naXQgYS9hcmNoL2FybTY0L2tlcm5lbC9zdGFj a3RyYWNlLmMgYi9hcmNoL2FybTY0L2tlcm5lbC9zdGFja3RyYWNlLmMKPiA+IGluZGV4IDYzNDI3 OWIzYjAzZC4uMTE3ZTJjMTgwZjNjIDEwMDY0NAo+ID4gLS0tIGEvYXJjaC9hcm02NC9rZXJuZWwv c3RhY2t0cmFjZS5jCj4gPiArKysgYi9hcmNoL2FybTY0L2tlcm5lbC9zdGFja3RyYWNlLmMKPiA+ IEBAIC0yMyw4ICsyMyw4IEBACj4gPiAgICoKPiA+ICAgKiBUaGUgcmVncyBtdXN0IGJlIG9uIGEg c3RhY2sgY3VycmVudGx5IG93bmVkIGJ5IHRoZSBjYWxsaW5nIHRhc2suCj4gPiAgICovCj4gPiAt c3RhdGljIGlubGluZSB2b2lkIHVud2luZF9pbml0X2Zyb21fcmVncyhzdHJ1Y3QgdW53aW5kX3N0 YXRlICpzdGF0ZSwKPiA+IC0JCQkJCSBzdHJ1Y3QgcHRfcmVncyAqcmVncykKPiA+ICtzdGF0aWMg X19hbHdheXNfaW5saW5lIHZvaWQgdW53aW5kX2luaXRfZnJvbV9yZWdzKHN0cnVjdCB1bndpbmRf c3RhdGUgKnN0YXRlLAo+ID4gKwkJCQkJCSAgc3RydWN0IHB0X3JlZ3MgKnJlZ3MpCj4gPiAgewo+ ID4gIAl1bndpbmRfaW5pdF9jb21tb24oc3RhdGUsIGN1cnJlbnQpOwo+ID4gIAo+ID4gQEAgLTU4 LDggKzU4LDggQEAgc3RhdGljIF9fYWx3YXlzX2lubGluZSB2b2lkIHVud2luZF9pbml0X2Zyb21f Y2FsbGVyKHN0cnVjdCB1bndpbmRfc3RhdGUgKnN0YXRlKQo+ID4gICAqIGR1cmF0aW9uIG9mIHRo ZSB1bndpbmQsIG9yIHRoZSB1bndpbmQgd2lsbCBiZSBib2d1cy4gSXQgaXMgbmV2ZXIgdmFsaWQg dG8KPiA+ICAgKiBjYWxsIHRoaXMgZm9yIHRoZSBjdXJyZW50IHRhc2suCj4gPiAgICovCj4gPiAt c3RhdGljIGlubGluZSB2b2lkIHVud2luZF9pbml0X2Zyb21fdGFzayhzdHJ1Y3QgdW53aW5kX3N0 YXRlICpzdGF0ZSwKPiA+IC0JCQkJCSBzdHJ1Y3QgdGFza19zdHJ1Y3QgKnRhc2spCj4gPiArc3Rh dGljIF9fYWx3YXlzX2lubGluZSB2b2lkIHVud2luZF9pbml0X2Zyb21fdGFzayhzdHJ1Y3QgdW53 aW5kX3N0YXRlICpzdGF0ZSwKPiA+ICsJCQkJCQkgIHN0cnVjdCB0YXNrX3N0cnVjdCAqdGFzaykK PiA+ICB7Cj4gPiAgCXVud2luZF9pbml0X2NvbW1vbihzdGF0ZSwgdGFzayk7Cj4gPiAgCj4gPiBA QCAtMTg2LDcgKzE4Niw3IEBAIHZvaWQgc2hvd19zdGFjayhzdHJ1Y3QgdGFza19zdHJ1Y3QgKnRz aywgdW5zaWduZWQgbG9uZyAqc3AsIGNvbnN0IGNoYXIgKmxvZ2x2bCkKPiA+ICAJCQk6IHN0YWNr aW5mb19nZXRfdW5rbm93bigpOwkJXAo+ID4gIAl9KQo+ID4gIAo+ID4gLW5vaW5saW5lIG5vdHJh Y2Ugdm9pZCBhcmNoX3N0YWNrX3dhbGsoc3RhY2tfdHJhY2VfY29uc3VtZV9mbiBjb25zdW1lX2Vu dHJ5LAo+ID4gK25vaW5saW5lIG5vaW5zdHIgdm9pZCBhcmNoX3N0YWNrX3dhbGsoc3RhY2tfdHJh Y2VfY29uc3VtZV9mbiBjb25zdW1lX2VudHJ5LAo+ID4gIAkJCSAgICAgIHZvaWQgKmNvb2tpZSwg c3RydWN0IHRhc2tfc3RydWN0ICp0YXNrLAo+ID4gIAkJCSAgICAgIHN0cnVjdCBwdF9yZWdzICpy ZWdzKQo+ID4gIHsKPiA+IAoKCi0tIApNYXNhbWkgSGlyYW1hdHN1IChHb29nbGUpIDxtaGlyYW1h dEBrZXJuZWwub3JnPgoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxpc3QKbGludXgtYXJtLWtlcm5lbEBsaXN0 cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGlu Zm8vbGludXgtYXJtLWtlcm5lbAo= 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4529C47089 for ; Tue, 6 Dec 2022 00:42:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232657AbiLFAmR (ORCPT ); Mon, 5 Dec 2022 19:42:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233461AbiLFAlm (ORCPT ); Mon, 5 Dec 2022 19:41:42 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80886DFD for ; Mon, 5 Dec 2022 16:41:41 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F0BED614F3 for ; Tue, 6 Dec 2022 00:41:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5D46C433D7; Tue, 6 Dec 2022 00:41:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670287300; bh=PHYevn3Vh1bRzHgX8jaY2KGyymMFzZcEuYmLigdgpFY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HREFEuzQkgTBk6bZMKgFTiB8CEqWJP4JL8snfVoRvIFSkAZ+1NqBLredgeO8ut1cI BOCHfhAqHxu+dA2bgYxP72JxkG+Gy/Sb6KaWcp3aGAOaIyiFMGTIitp2hUrt2OkapU UjjZ/H0gJGeA1B5qfjLOwgoLEHrUJ9rGV8e4GsBICCkZLUqsLbhGscY9VEN+qfj3uR jcOUGDFq3BRpWgEw3W6ccjdbsGFr9S8LQVsrLgFc0+etQ/hbpIelyT4Mf4ZxXMLSvC M7DFFBwFk0gz9Zjfm9ZLS0b5J3tleD6OzTi2zgEMy56r7dlgWBo1NP5HB5ECKb3ABq DYs50wj3+Gm9A== Date: Tue, 6 Dec 2022 09:41:37 +0900 From: Masami Hiramatsu (Google) To: Mark Rutland Cc: Catalin Marinas , Will Deacon , Mark Brown , Kalesh Singh , Marc Zyngier , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sandeepa Prabhu Subject: Re: [PATCH v2 1/3] arm64: Prohibit instrumentation on arch_stack_walk() Message-Id: <20221206094137.389e4c374f4be060af19f33a@kernel.org> In-Reply-To: References: <166994750386.439920.1754385804350980158.stgit@devnote3> <166994751368.439920.3236636557520824664.stgit@devnote3> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2 Dec 2022 13:17:30 +0000 Mark Rutland wrote: > On Fri, Dec 02, 2022 at 11:18:33AM +0900, Masami Hiramatsu (Google) wrote: > > From: Masami Hiramatsu (Google) > > > > Mark arch_stack_walk() as noinstr instead of notrace and inline functions > > called from arch_stack_walk() as __always_inline so that user does not > > put any instrumentations on it, because this function can be used from > > return_address() which is used by lockdep. > > Hmmm... since arch_stack_walk is marked as notrace, that will be prohibited by > default unless the kernel was built with CONFIG_KPROBE_EVENTS_ON_NOTRACE=y, > and the commit message for that says: > > │ This option disables such protection and allows you to put kprobe │ > │ events on ftrace functions for debugging ftrace by itself. │ > │ Note that this might let you shoot yourself in the foot. > > ... and IIUC we generally don't expect people to set that, and that might be > worth calling out in the commit message. Yeah, but that is the feature for kprobe events, and not applied to the kprobes itself. Maybe I should use a test kprobe module to put a probe on it. > > > Without this, if the kernel built with CONFIG_LOCKDEP=y, just probing > > arch_stack_walk() via /kprobe_events will crash the kernel on > > arm64. > > > > # echo p arch_stack_walk >> ${TRACEFS}/kprobe_events > > # echo 1 > ${TRACEFS}/events/kprobes/enable > > I had a go at testing this patch, and it fixes the crash with the reproducer > above, but there are plenty of other instances in stacktrace.c that lead to the > same sort of crash, e.g. > > # echo p stackinfo_get_task >> ${TRACEFS}/kprobe_events > # echo 1 > ${TRACEFS}/events/kprobes/enable Oops, thanks for pointing! Hmm, I thought stackinfo_get_task() is an inlined function usually. Maybe we should make it nokprobe_inline. But this is just one case. I need to scan all symbols to trace... > > ... so I think there's more that we need to do to fix this generally. > > Note: I found interesting functions to try tracing by looking at the output of: > > aarch64-linux-objdump -t arch/arm64/kernel/stacktrace.o | grep -w '.text' > > That all said, I think this patch is nice-to-have, and that we can address the > other cases as a follow-up, so for this patch as-is (with or without some > wording regarding CONFIG_KPROBE_EVENTS_ON_NOTRACE): > > Acked-by: Mark Rutland Thanks! > > Mark. > > > kprobes: Failed to recover from reentered kprobes. > > kprobes: Dump kprobe: > > .symbol_name = arch_stack_walk, .offset = 0, .addr = arch_stack_walk+0x0/0x1c0 > > ------------[ cut here ]------------ > > kernel BUG at arch/arm64/kernel/probes/kprobes.c:241! > > kprobes: Failed to recover from reentered kprobes. > > kprobes: Dump kprobe: > > .symbol_name = arch_stack_walk, .offset = 0, .addr = arch_stack_walk+0x0/0x1c0 > > ------------[ cut here ]------------ > > kernel BUG at arch/arm64/kernel/probes/kprobes.c:241! > > PREEMPT SMP > > Modules linked in: > > CPU: 0 PID: 17 Comm: migration/0 Tainted: G N 6.1.0-rc5+ #6 > > Hardware name: linux,dummy-virt (DT) > > Stopper: 0x0 <- 0x0 > > pstate: 600003c5 (nZCv DAIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > > pc : kprobe_breakpoint_handler+0x178/0x17c > > lr : kprobe_breakpoint_handler+0x178/0x17c > > sp : ffff8000080d3090 > > x29: ffff8000080d3090 x28: ffff0df5845798c0 x27: ffffc4f59057a774 > > x26: ffff0df5ffbba770 x25: ffff0df58f420f18 x24: ffff49006f641000 > > x23: ffffc4f590579768 x22: ffff0df58f420f18 x21: ffff8000080d31c0 > > x20: ffffc4f590579768 x19: ffffc4f590579770 x18: 0000000000000006 > > x17: 5f6b636174735f68 x16: 637261203d207264 x15: 64612e202c30203d > > x14: 2074657366666f2e x13: 30633178302f3078 x12: 302b6b6c61775f6b > > x11: 636174735f686372 x10: ffffc4f590dc5bd8 x9 : ffffc4f58eb31958 > > x8 : 00000000ffffefff x7 : ffffc4f590dc5bd8 x6 : 80000000fffff000 > > x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000 > > x2 : 0000000000000000 x1 : ffff0df5845798c0 x0 : 0000000000000064 > > Call trace: > > kprobes: Failed to recover from reentered kprobes. > > kprobes: Dump kprobe: > > .symbol_name = arch_stack_walk, .offset = 0, .addr = arch_stack_walk+0x0/0x1c0 > > ------------[ cut here ]------------ > > kernel BUG at arch/arm64/kernel/probes/kprobes.c:241! > > > > Fixes: 39ef362d2d45 ("arm64: Make return_address() use arch_stack_walk()") > > Cc: stable@vger.kernel.org > > Signed-off-by: Masami Hiramatsu (Google) > > --- > > Changes in v2: > > - Use noinstr instead of NOKPROBE_SYMBOL() > > - Use __always_inline because nokprobe_inline will be changed if > > CONFIG_KPROBES=n. > > - Fix indentation. > > --- > > arch/arm64/kernel/stacktrace.c | 10 +++++----- > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c > > index 634279b3b03d..117e2c180f3c 100644 > > --- a/arch/arm64/kernel/stacktrace.c > > +++ b/arch/arm64/kernel/stacktrace.c > > @@ -23,8 +23,8 @@ > > * > > * The regs must be on a stack currently owned by the calling task. > > */ > > -static inline void unwind_init_from_regs(struct unwind_state *state, > > - struct pt_regs *regs) > > +static __always_inline void unwind_init_from_regs(struct unwind_state *state, > > + struct pt_regs *regs) > > { > > unwind_init_common(state, current); > > > > @@ -58,8 +58,8 @@ static __always_inline void unwind_init_from_caller(struct unwind_state *state) > > * duration of the unwind, or the unwind will be bogus. It is never valid to > > * call this for the current task. > > */ > > -static inline void unwind_init_from_task(struct unwind_state *state, > > - struct task_struct *task) > > +static __always_inline void unwind_init_from_task(struct unwind_state *state, > > + struct task_struct *task) > > { > > unwind_init_common(state, task); > > > > @@ -186,7 +186,7 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl) > > : stackinfo_get_unknown(); \ > > }) > > > > -noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry, > > +noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, > > void *cookie, struct task_struct *task, > > struct pt_regs *regs) > > { > > -- Masami Hiramatsu (Google)