From patchwork Thu Dec 14 10:17:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Roger_Pau_Monn=C3=A9?= X-Patchwork-Id: 13492703 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 3F8F2C10F13 for ; Thu, 14 Dec 2023 10:18:00 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.654403.1021303 (Exim 4.92) (envelope-from ) id 1rDimo-0006ar-QW; Thu, 14 Dec 2023 10:17:46 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 654403.1021303; Thu, 14 Dec 2023 10:17:46 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rDimo-0006ZQ-Ig; Thu, 14 Dec 2023 10:17:46 +0000 Received: by outflank-mailman (input) for mailman id 654403; Thu, 14 Dec 2023 10:17:45 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1rDimn-0006Da-CH for xen-devel@lists.xenproject.org; Thu, 14 Dec 2023 10:17:45 +0000 Received: from mail-wm1-x32d.google.com (mail-wm1-x32d.google.com [2a00:1450:4864:20::32d]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 0554b220-9a6a-11ee-98e9-6d05b1d4d9a1; Thu, 14 Dec 2023 11:17:44 +0100 (CET) Received: by mail-wm1-x32d.google.com with SMTP id 5b1f17b1804b1-40c2db2ee28so84621525e9.2 for ; Thu, 14 Dec 2023 02:17:44 -0800 (PST) Received: from localhost ([213.195.127.70]) by smtp.gmail.com with ESMTPSA id gw18-20020a05600c851200b004053e9276easm26276280wmb.32.2023.12.14.02.17.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Dec 2023 02:17:43 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 0554b220-9a6a-11ee-98e9-6d05b1d4d9a1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1702549063; x=1703153863; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=7uem9HU9IMtRwRD4U1/+rZK9QwDDjIx6C/QW5H+G6tU=; b=eoScLbzCAlE+/+SQ0LdM0UkCB0eQ2O+YnyhC7mM9Rqbdyo3X8Lv1gqdPOiaNhOWTqJ i2460U2w7yh7UZssuOM1jDG4JhmmWZK23Au25im76OUWlU0a+xuZj4wOlDmH8JRYcVv+ V/zKnK1xl2sPyyV0bmqxoO+1DmQF40unQnNKo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702549063; x=1703153863; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=7uem9HU9IMtRwRD4U1/+rZK9QwDDjIx6C/QW5H+G6tU=; b=PGCrmr8I5nyNZlIkCni8RvlFAjOF723rLJd4oGpLlyxKt+Oy7sS1Mct0h/Heok1mBj 32EGKtlpDZdbboaehWHS4JaBHvbUuJXf2/M/U9+tHfiinWmdMeXnI5Im3QnZJokGtFCC zYXyHcH0UZ/UV7r4YvEsBIyMnxZyFZJOxmBePFfjEJHllFZRRWy1q1fmwGT92BZv0G5w 4SP60al2K7/aAVl4eYAfM7cF8km7CoeSpQKdPqDSSt8ghIHHqKJJT+cnA1L2VlC67MvR MUF2xKaq3NZbQXGWwG/wiJc9E3Yt/KRHByCxILsFO4yrTHKKrBIsiQHY8Pa85WgH1dj2 pQDg== X-Gm-Message-State: AOJu0YzeKOUWVNShqHywYrkAg7IYbCAuqyxsrvjojJVMGqDepKpcqxEP WG32we7J0SV07BnpG97ONJH6ezyGiWeBcCLfB2w= X-Google-Smtp-Source: AGHT+IHCqH8ZUtNHk8Qx/sLuLfjtYkIYiJVgPji27dkFRJbFYjadLYaWNCkNyWDQXfD28fkQVvzpFw== X-Received: by 2002:a05:600c:1705:b0:40c:36ed:c5c6 with SMTP id c5-20020a05600c170500b0040c36edc5c6mr5405038wmn.29.1702549063621; Thu, 14 Dec 2023 02:17:43 -0800 (PST) From: Roger Pau Monne To: xen-devel@lists.xenproject.org Cc: Roger Pau Monne , Konrad Rzeszutek Wilk , Ross Lagerwall , Wei Liu , Anthony PERARD , Andrew Cooper , George Dunlap , Jan Beulich , Julien Grall , Stefano Stabellini Subject: [PATCH v3 3/4] x86/livepatch: introduce a basic live patch test to gitlab CI Date: Thu, 14 Dec 2023 11:17:18 +0100 Message-ID: <20231214101719.18770-4-roger.pau@citrix.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231214101719.18770-1-roger.pau@citrix.com> References: <20231214101719.18770-1-roger.pau@citrix.com> MIME-Version: 1.0 Introduce a basic livepatch test using the interface to run self modifying tests. The introduced test relies on changing a function from returning false to returning true. To simplify the burden of keeping a patch that can be provided to livepatch-build-tools, introduce two new files: one containing the unpatched test functions, and another one that contains the patched forms of such functions. Note that only the former is linked into the Xen image, the latter is built but the object file is not consumed afterwards. Do this to assert that the file containing the patched functions continues to build. Since livepatch testing will ensure that the functions are not patched previous the applying the livepatch, allow the livepatch related tests to fail without tainting the hypervisor. Note the livepatch tests are not run as part of the self modifying checks executed during boot, as they would obviously fail. Signed-off-by: Roger Pau Monné Acked-by: Jan Beulich --- Changes since v2: - Clarify comment about xor vs mov instructions for return false/true encodings. Changes since v1: - New interface & test. --- tools/misc/xen-livepatch.c | 29 ++++++++++++++++++++++++++++ xen/arch/x86/include/asm/test-smoc.h | 4 ++++ xen/arch/x86/setup.c | 2 +- xen/arch/x86/test/Makefile | 2 ++ xen/arch/x86/test/smoc-lp-alt.c | 24 +++++++++++++++++++++++ xen/arch/x86/test/smoc-lp.c | 24 +++++++++++++++++++++++ xen/arch/x86/test/smoc.c | 11 ++++++++++- xen/include/public/sysctl.h | 6 +++++- 8 files changed, 99 insertions(+), 3 deletions(-) create mode 100644 xen/arch/x86/test/smoc-lp-alt.c create mode 100644 xen/arch/x86/test/smoc-lp.c diff --git a/tools/misc/xen-livepatch.c b/tools/misc/xen-livepatch.c index 5bf9d9a32b65..4ebd1b4e936d 100644 --- a/tools/misc/xen-livepatch.c +++ b/tools/misc/xen-livepatch.c @@ -37,6 +37,7 @@ void show_help(void) " replace apply patch and revert all others.\n" " unload unload name patch.\n" " load [flags] upload and apply with name as the name\n" + " test execute self modifying code livepatch hypervisor tests\n" " Supported flags:\n" " --nodeps Disable inter-module buildid dependency check.\n" " Check only against hypervisor buildid.\n", @@ -542,6 +543,33 @@ error: return rc; } +static int test_func(int argc, char *argv[]) +{ + uint32_t results = 0; + int rc; + + if ( argc != 0 ) + { + show_help(); + return -1; + } + + rc = xc_test_smoc(xch, XEN_SYSCTL_TEST_SMOC_LP, &results); + if ( rc ) + { + fprintf(stderr, "test operation failed: %s\n", strerror(errno)); + return -1; + } + if ( (results & XEN_SYSCTL_TEST_SMOC_LP) != XEN_SYSCTL_TEST_SMOC_LP ) + { + fprintf(stderr, "some tests failed: %#x (expected %#x)\n", + results, XEN_SYSCTL_TEST_SMOC_LP); + return -1; + } + + return 0; +} + /* * These are also functions in action_options that are called in case * none of the ones in main_options match. @@ -554,6 +582,7 @@ struct { { "list", list_func }, { "upload", upload_func }, { "load", load_func }, + { "test", test_func }, }; int main(int argc, char *argv[]) diff --git a/xen/arch/x86/include/asm/test-smoc.h b/xen/arch/x86/include/asm/test-smoc.h index 2547b925d291..d369cf39687c 100644 --- a/xen/arch/x86/include/asm/test-smoc.h +++ b/xen/arch/x86/include/asm/test-smoc.h @@ -5,6 +5,10 @@ int test_smoc(uint32_t selection, uint32_t *results); +#ifdef CONFIG_LIVEPATCH +bool cf_check test_lp_insn_replacement(void); +#endif + #endif /* _ASM_X86_TEST_SMC_H_ */ /* diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c index e026b0ea5adc..b97faa7a3e97 100644 --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -1952,7 +1952,7 @@ void asmlinkage __init noreturn __start_xen(unsigned long mbi_p) alternative_branches(); - test_smoc(XEN_SYSCTL_TEST_SMOC_ALL, NULL); + test_smoc(XEN_SYSCTL_TEST_SMOC_ALL & ~XEN_SYSCTL_TEST_SMOC_LP, NULL); /* * NB: when running as a PV shim VCPUOP_up/down is wired to the shim diff --git a/xen/arch/x86/test/Makefile b/xen/arch/x86/test/Makefile index b504b8196659..3a5a0a98e4db 100644 --- a/xen/arch/x86/test/Makefile +++ b/xen/arch/x86/test/Makefile @@ -1 +1,3 @@ obj-y += smoc.o +obj-$(CONFIG_LIVEPATCH) += smoc-lp.o # for livepatch testing +extra-$(CONFIG_LIVEPATCH) += smoc-lp-alt.o diff --git a/xen/arch/x86/test/smoc-lp-alt.c b/xen/arch/x86/test/smoc-lp-alt.c new file mode 100644 index 000000000000..d054e9bedc51 --- /dev/null +++ b/xen/arch/x86/test/smoc-lp-alt.c @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include + +/* + * Interesting case because `return false` can be encoded as `xor %eax, %eax`, + * which is shorter than `return true` which is encoded as a `mov $1, %eax` + * instruction (based on code generated by GCC 13.2 at -O2), and also shorter + * than the replacement `jmp` instruction. + */ +bool cf_check test_lp_insn_replacement(void) +{ + return true; +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/arch/x86/test/smoc-lp.c b/xen/arch/x86/test/smoc-lp.c new file mode 100644 index 000000000000..e972791480b5 --- /dev/null +++ b/xen/arch/x86/test/smoc-lp.c @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include + +/* + * Interesting case because `return false` can be encoded as `xor %eax, %eax`, + * which is shorter than `return true` which is encoded as a `mov $1, %eax` + * instruction (based on code generated by GCC 13.2 at -O2), and also shorter + * than the replacement `jmp` instruction. + */ +bool cf_check test_lp_insn_replacement(void) +{ + return false; +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/arch/x86/test/smoc.c b/xen/arch/x86/test/smoc.c index e7529f937a5a..8e74d26432ee 100644 --- a/xen/arch/x86/test/smoc.c +++ b/xen/arch/x86/test/smoc.c @@ -27,6 +27,10 @@ int test_smoc(uint32_t selection, uint32_t *results) } static const tests[] = { { XEN_SYSCTL_TEST_SMOC_INSN_REPL, &test_insn_replacement, "alternative instruction replacement" }, +#ifdef CONFIG_LIVEPATCH + { XEN_SYSCTL_TEST_SMOC_LP_INSN, &test_lp_insn_replacement, + "livepatch instruction replacement" }, +#endif }; unsigned int i; @@ -50,7 +54,12 @@ int test_smoc(uint32_t selection, uint32_t *results) continue; } - add_taint(TAINT_ERROR_SMOC); + /* + * livepatch related tests don't taint the hypervisor because we also + * want to check the failing case. + */ + if ( !(tests[i].mask & XEN_SYSCTL_TEST_SMOC_LP) ) + add_taint(TAINT_ERROR_SMOC); printk(XENLOG_ERR "%s test failed\n", tests[i].name); } diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h index 4b17f1344732..aa4068d6996b 100644 --- a/xen/include/public/sysctl.h +++ b/xen/include/public/sysctl.h @@ -1205,7 +1205,11 @@ struct xen_sysctl_dt_overlay { struct xen_sysctl_test_smoc { uint32_t tests; /* IN: bitmap with selected tests to execute. */ #define XEN_SYSCTL_TEST_SMOC_INSN_REPL (1U << 0) -#define XEN_SYSCTL_TEST_SMOC_ALL (XEN_SYSCTL_TEST_SMOC_INSN_REPL) +#define XEN_SYSCTL_TEST_SMOC_LP_INSN (1U << 1) +#define XEN_SYSCTL_TEST_SMOC_ALL (XEN_SYSCTL_TEST_SMOC_INSN_REPL | \ + XEN_SYSCTL_TEST_SMOC_LP_INSN) +#define XEN_SYSCTL_TEST_SMOC_LP (XEN_SYSCTL_TEST_SMOC_LP_INSN) + uint32_t results; /* OUT: test result: 1 -> success, 0 -> failure. */ };