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=-12.1 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 14B50C433E6 for ; Fri, 28 Aug 2020 14:28:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAE712078A for ; Fri, 28 Aug 2020 14:28:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727863AbgH1O2u (ORCPT ); Fri, 28 Aug 2020 10:28:50 -0400 Received: from foss.arm.com ([217.140.110.172]:50684 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726614AbgH1O2s (ORCPT ); Fri, 28 Aug 2020 10:28:48 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 32F8D1FB; Fri, 28 Aug 2020 07:28:47 -0700 (PDT) Received: from [192.168.1.190] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DE1133F71F; Fri, 28 Aug 2020 07:28:45 -0700 (PDT) Subject: Re: [PATCH 2/4] kselftests/arm64: add nop checks for PAuth tests To: Boyan Karatotev , linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: amit.kachhap@arm.com, boian4o1@gmail.com, Shuah Khan , Catalin Marinas , Will Deacon References: <20200828131606.7946-1-boyan.karatotev@arm.com> <20200828131606.7946-3-boyan.karatotev@arm.com> From: Vincenzo Frascino Message-ID: <96f6009c-9f61-ebd2-9a2f-7d54486e85eb@arm.com> Date: Fri, 28 Aug 2020 15:30:51 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200828131606.7946-3-boyan.karatotev@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/28/20 2:16 PM, Boyan Karatotev wrote: > PAuth adds sign/verify controls to enable and disable groups of > instructions in hardware for compatibility with libraries that do not > implement PAuth. The kernel always enables them if it detects PAuth. > > Add a test that checks that each group of instructions is enabled, if the > kernel reports PAuth as detected. > > Note: For groups, for the purpose of this patch, we intend instructions > that use a certain key. > Reviewed-by: Vincenzo Frascino > Cc: Shuah Khan > Cc: Catalin Marinas > Cc: Will Deacon > Signed-off-by: Boyan Karatotev > --- > .../testing/selftests/arm64/pauth/.gitignore | 1 + > tools/testing/selftests/arm64/pauth/Makefile | 7 ++- > tools/testing/selftests/arm64/pauth/helper.c | 41 +++++++++++++++ > tools/testing/selftests/arm64/pauth/helper.h | 10 ++++ > tools/testing/selftests/arm64/pauth/pac.c | 51 +++++++++++++++++++ > 5 files changed, 108 insertions(+), 2 deletions(-) > create mode 100644 tools/testing/selftests/arm64/pauth/helper.c > > diff --git a/tools/testing/selftests/arm64/pauth/.gitignore b/tools/testing/selftests/arm64/pauth/.gitignore > index b557c916720a..155137d92722 100644 > --- a/tools/testing/selftests/arm64/pauth/.gitignore > +++ b/tools/testing/selftests/arm64/pauth/.gitignore > @@ -1 +1,2 @@ > +exec_target > pac > diff --git a/tools/testing/selftests/arm64/pauth/Makefile b/tools/testing/selftests/arm64/pauth/Makefile > index 785c775e5e41..a017d1c8dd58 100644 > --- a/tools/testing/selftests/arm64/pauth/Makefile > +++ b/tools/testing/selftests/arm64/pauth/Makefile > @@ -4,7 +4,7 @@ > CFLAGS += -mbranch-protection=pac-ret > > TEST_GEN_PROGS := pac > -TEST_GEN_FILES := pac_corruptor.o > +TEST_GEN_FILES := pac_corruptor.o helper.o > > include ../../lib.mk > > @@ -13,10 +13,13 @@ include ../../lib.mk > $(OUTPUT)/pac_corruptor.o: pac_corruptor.S > $(CC) -c $^ -o $@ $(CFLAGS) -march=armv8.3-a > > +$(OUTPUT)/helper.o: helper.c > + $(CC) -c $^ -o $@ $(CFLAGS) -march=armv8.3-a > + > # when -mbranch-protection is enabled and the target architecture is ARMv8.3 or > # greater, gcc emits pac* instructions which are not in HINT NOP space, > # preventing the tests from occurring at all. Compile for ARMv8.2 so tests can > # run on earlier targets and print a meaningful error messages > -$(OUTPUT)/pac: pac.c $(OUTPUT)/pac_corruptor.o > +$(OUTPUT)/pac: pac.c $(OUTPUT)/pac_corruptor.o $(OUTPUT)/helper.o > $(CC) $^ -o $@ $(CFLAGS) -march=armv8.2-a > > diff --git a/tools/testing/selftests/arm64/pauth/helper.c b/tools/testing/selftests/arm64/pauth/helper.c > new file mode 100644 > index 000000000000..8619afb16124 > --- /dev/null > +++ b/tools/testing/selftests/arm64/pauth/helper.c > @@ -0,0 +1,41 @@ > +// SPDX-License-Identifier: GPL-2.0 > +// Copyright (C) 2020 ARM Limited > + > +#include "helper.h" > + > + > +size_t keyia_sign(size_t ptr) > +{ > + asm volatile("paciza %0" : "+r" (ptr)); > + return ptr; > +} > + > +size_t keyib_sign(size_t ptr) > +{ > + asm volatile("pacizb %0" : "+r" (ptr)); > + return ptr; > +} > + > +size_t keyda_sign(size_t ptr) > +{ > + asm volatile("pacdza %0" : "+r" (ptr)); > + return ptr; > +} > + > +size_t keydb_sign(size_t ptr) > +{ > + asm volatile("pacdzb %0" : "+r" (ptr)); > + return ptr; > +} > + > +size_t keyg_sign(size_t ptr) > +{ > + /* output is encoded in the upper 32 bits */ > + size_t dest = 0; > + size_t modifier = 0; > + > + asm volatile("pacga %0, %1, %2" : "=r" (dest) : "r" (ptr), "r" (modifier)); > + > + return dest; > +} > + > diff --git a/tools/testing/selftests/arm64/pauth/helper.h b/tools/testing/selftests/arm64/pauth/helper.h > index f777f88acf0a..b3cf709e249d 100644 > --- a/tools/testing/selftests/arm64/pauth/helper.h > +++ b/tools/testing/selftests/arm64/pauth/helper.h > @@ -4,7 +4,17 @@ > #ifndef _HELPER_H_ > #define _HELPER_H_ > > +#include > + > + > void pac_corruptor(void); > > +/* PAuth sign a value with key ia and modifier value 0 */ > +size_t keyia_sign(size_t val); > +size_t keyib_sign(size_t val); > +size_t keyda_sign(size_t val); > +size_t keydb_sign(size_t val); > +size_t keyg_sign(size_t val); > + > #endif > > diff --git a/tools/testing/selftests/arm64/pauth/pac.c b/tools/testing/selftests/arm64/pauth/pac.c > index ed445050f621..cdbffa8bf61e 100644 > --- a/tools/testing/selftests/arm64/pauth/pac.c > +++ b/tools/testing/selftests/arm64/pauth/pac.c > @@ -12,12 +12,25 @@ > * future version of the arm architecture > */ > > +#define PAC_COLLISION_ATTEMPTS 10 > +/* > + * The kernel sets TBID by default. So bits 55 and above should remain > + * untouched no matter what. > + * The VA space size is 48 bits. Bigger is opt-in. > + */ > +#define PAC_MASK (~0xff80ffffffffffff) > #define ASSERT_PAUTH_ENABLED() \ > do { \ > unsigned long hwcaps = getauxval(AT_HWCAP); \ > /* data key instructions are not in NOP space. This prevents a SIGILL */ \ > ASSERT_NE(0, hwcaps & HWCAP_PACA) TH_LOG("PAUTH not enabled"); \ > } while (0) > +#define ASSERT_GENERIC_PAUTH_ENABLED() \ > +do { \ > + unsigned long hwcaps = getauxval(AT_HWCAP); \ > + /* generic key instructions are not in NOP space. This prevents a SIGILL */ \ > + ASSERT_NE(0, hwcaps & HWCAP_PACG) TH_LOG("Generic PAUTH not enabled"); \ > +} while (0) > > > /* check that a corrupted PAC results in SIGSEGV */ > @@ -28,5 +41,43 @@ TEST_SIGNAL(corrupt_pac, SIGSEGV) > pac_corruptor(); > } > > +/* > + * There are no separate pac* and aut* controls so checking only the pac* > + * instructions is sufficient > + */ > +TEST(pac_instructions_not_nop) > +{ > + size_t keyia = 0; > + size_t keyib = 0; > + size_t keyda = 0; > + size_t keydb = 0; > + > + ASSERT_PAUTH_ENABLED(); > + > + for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) { > + keyia |= keyia_sign(i) & PAC_MASK; > + keyib |= keyib_sign(i) & PAC_MASK; > + keyda |= keyda_sign(i) & PAC_MASK; > + keydb |= keydb_sign(i) & PAC_MASK; > + } > + > + ASSERT_NE(0, keyia) TH_LOG("keyia instructions did nothing"); > + ASSERT_NE(0, keyib) TH_LOG("keyib instructions did nothing"); > + ASSERT_NE(0, keyda) TH_LOG("keyda instructions did nothing"); > + ASSERT_NE(0, keydb) TH_LOG("keydb instructions did nothing"); > +} > + > +TEST(pac_instructions_not_nop_generic) > +{ > + size_t keyg = 0; > + > + ASSERT_GENERIC_PAUTH_ENABLED(); > + > + for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) > + keyg |= keyg_sign(i) & PAC_MASK; > + > + ASSERT_NE(0, keyg) TH_LOG("keyg instructions did nothing"); > +} > + > TEST_HARNESS_MAIN > > -- Regards, Vincenzo