From patchwork Wed Aug 14 08:39:11 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Wieczorkiewicz, Pawel" X-Patchwork-Id: 11093507 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E9F546C5 for ; Wed, 14 Aug 2019 08:41:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D47F628514 for ; Wed, 14 Aug 2019 08:41:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C6A9028759; Wed, 14 Aug 2019 08:41:01 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00,DKIM_ADSP_ALL, DKIM_INVALID,DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 6192E28514 for ; Wed, 14 Aug 2019 08:41:00 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hxooT-0005Ma-1H; Wed, 14 Aug 2019 08:39:21 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hxooS-0005MP-Bl for xen-devel@lists.xen.org; Wed, 14 Aug 2019 08:39:20 +0000 X-Inumbo-ID: 022a4192-be6f-11e9-8e6c-d7da2c9c0119 Received: from smtp-fw-4101.amazon.com (unknown [72.21.198.25]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 022a4192-be6f-11e9-8e6c-d7da2c9c0119; Wed, 14 Aug 2019 08:39:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.de; i=@amazon.de; q=dns/txt; s=amazon201209; t=1565771959; x=1597307959; h=from:to:cc:subject:date:message-id:mime-version; bh=ExoS4xKNzxP2qt6yxq+ISJiAVws8oKZS3GmoXLikevU=; b=lir24L5zunWfuFuH5B4ibVkhxuUmy7Skl3NvfKzIwJeoI/0T2svKBhNT t1f0R0jtwTm0xA0NduTU6o3qDvl9dkuMz0W7ykHs7Kv5phaoHj7U7eQzk DiqgPleNJCc3BGg98jpSHQ3nw7zBppu4X0yBucb80o8qn53wQv4D1f5pz E=; X-IronPort-AV: E=Sophos;i="5.64,384,1559520000"; d="scan'208";a="779192998" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-2c-2225282c.us-west-2.amazon.com) ([10.124.125.6]) by smtp-border-fw-out-4101.iad4.amazon.com with ESMTP; 14 Aug 2019 08:39:18 +0000 Received: from EX13MTAUEA001.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2c-2225282c.us-west-2.amazon.com (Postfix) with ESMTPS id B670DA25B6; Wed, 14 Aug 2019 08:39:17 +0000 (UTC) Received: from EX13D05EUC001.ant.amazon.com (10.43.164.118) by EX13MTAUEA001.ant.amazon.com (10.43.61.82) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Wed, 14 Aug 2019 08:39:17 +0000 Received: from EX13MTAUWA001.ant.amazon.com (10.43.160.58) by EX13D05EUC001.ant.amazon.com (10.43.164.118) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Wed, 14 Aug 2019 08:39:15 +0000 Received: from dev-dsk-wipawel-1a-0c4e6d58.eu-west-1.amazon.com (10.4.134.33) by mail-relay.amazon.com (10.43.160.118) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Wed, 14 Aug 2019 08:39:14 +0000 From: Pawel Wieczorkiewicz To: Date: Wed, 14 Aug 2019 08:39:11 +0000 Message-ID: <20190814083911.89280-1-wipawel@amazon.de> X-Mailer: git-send-email 2.16.5 MIME-Version: 1.0 Precedence: Bulk Subject: [Xen-devel] [livepatch-hooks-2 PATCH 4/4] livepatch: Add per-function applied/reverted state tracking marker X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: mpohlack@amazon.de, ross.lagerwall@citrix.com, wipawel@amazon.de, konrad.wilk@oracle.com Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP Livepatch only tracks an entire payload applied/reverted state. But, with an option to supply the apply_payload() and/or revert_payload() functions as optional hooks, it becomes possible to intermix the execution of the original apply_payload()/revert_payload() functions with their dynamically supplied counterparts. It is important then to track the current state of every function being patched and prevent situations of unintentional double-apply or unapplied revert. To support that, it is necessary to extend public interface of the livepatch. The struct livepatch_func gets additional field holding the applied/reverted state marker. To reflect the livepatch payload ABI change, bump the version flag LIVEPATCH_PAYLOAD_VERSION up to 2. The above solution only applies to x86 architecture for now. Signed-off-by: Pawel Wieczorkiewicz Reviewed-by: Andra-Irina Paraschiv Reviewed-by: Bjoern Doebel Reviewed-by: Martin Pohlack --- xen/arch/x86/livepatch.c | 20 +++++++++++++++++++- xen/common/livepatch.c | 35 +++++++++++++++++++++++++++++++++++ xen/include/public/sysctl.h | 11 ++++++++++- xen/include/xen/livepatch.h | 2 +- 4 files changed, 65 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/livepatch.c b/xen/arch/x86/livepatch.c index 436ee40fe1..76fa91a082 100644 --- a/xen/arch/x86/livepatch.c +++ b/xen/arch/x86/livepatch.c @@ -61,6 +61,14 @@ void noinline arch_livepatch_apply(struct livepatch_func *func) if ( !len ) return; + /* If the apply action has been already executed on this function, do nothing... */ + if ( func->applied == LIVEPATCH_FUNC_APPLIED ) + { + printk(XENLOG_WARNING LIVEPATCH "%s: %s has been already applied before\n", + __func__, func->name); + return; + } + memcpy(func->opaque, old_ptr, len); if ( func->new_addr ) { @@ -77,15 +85,25 @@ void noinline arch_livepatch_apply(struct livepatch_func *func) add_nops(insn, len); memcpy(old_ptr, insn, len); + func->applied = LIVEPATCH_FUNC_APPLIED; } /* * "noinline" to cause control flow change and thus invalidate I$ and * cause refetch after modification. */ -void noinline arch_livepatch_revert(const struct livepatch_func *func) +void noinline arch_livepatch_revert(struct livepatch_func *func) { + /* If the apply action hasn't been executed on this function, do nothing... */ + if ( !func->old_addr || func->applied == LIVEPATCH_FUNC_NOT_APPLIED ) + { + printk(XENLOG_WARNING LIVEPATCH "%s: %s has not been applied before\n", + __func__, func->name); + return; + } + memcpy(func->old_addr, func->opaque, livepatch_insn_len(func)); + func->applied = LIVEPATCH_FUNC_NOT_APPLIED; } /* diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c index 585ec9819a..090a48977b 100644 --- a/xen/common/livepatch.c +++ b/xen/common/livepatch.c @@ -1242,6 +1242,29 @@ static inline void revert_payload_tail(struct payload *data) data->state = LIVEPATCH_STATE_CHECKED; } +/* + * Check if an action has applied the same state to all payload's functions consistently. + */ +static inline bool was_action_consistent(const struct payload *data, livepatch_func_state_t expected_state) +{ + int i; + + for ( i = 0; i < data->nfuncs; i++ ) + { + struct livepatch_func *f = &(data->funcs[i]); + + if ( f->applied != expected_state ) + { + printk(XENLOG_ERR LIVEPATCH "%s: Payload has a function: '%s' with inconsistent applied state.\n", + data->name, f->name ?: "noname"); + + return false; + } + } + + return true; +} + /* * This function is executed having all other CPUs with no deep stack (we may * have cpu_idle on it) and IRQs disabled. @@ -1268,6 +1291,9 @@ static void livepatch_do_action(void) else rc = apply_payload(data); + if ( !was_action_consistent(data, rc ? LIVEPATCH_FUNC_NOT_APPLIED : LIVEPATCH_FUNC_APPLIED) ) + panic("livepatch: partially applied payload '%s'!\n", data->name); + if ( rc == 0 ) apply_payload_tail(data); break; @@ -1282,6 +1308,9 @@ static void livepatch_do_action(void) else rc = revert_payload(data); + if ( !was_action_consistent(data, rc ? LIVEPATCH_FUNC_APPLIED : LIVEPATCH_FUNC_NOT_APPLIED) ) + panic("livepatch: partially reverted payload '%s'!\n", data->name); + if ( rc == 0 ) revert_payload_tail(data); break; @@ -1304,6 +1333,9 @@ static void livepatch_do_action(void) other->rc = revert_payload(other); + if ( !was_action_consistent(other, rc ? LIVEPATCH_FUNC_APPLIED : LIVEPATCH_FUNC_NOT_APPLIED) ) + panic("livepatch: partially reverted payload '%s'!\n", other->name); + if ( other->rc == 0 ) revert_payload_tail(other); else @@ -1324,6 +1356,9 @@ static void livepatch_do_action(void) else rc = apply_payload(data); + if ( !was_action_consistent(data, rc ? LIVEPATCH_FUNC_NOT_APPLIED : LIVEPATCH_FUNC_APPLIED) ) + panic("livepatch: partially applied payload '%s'!\n", data->name); + if ( rc == 0 ) apply_payload_tail(data); } diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h index cfbb8760d4..98cdcc64bb 100644 --- a/xen/include/public/sysctl.h +++ b/xen/include/public/sysctl.h @@ -818,7 +818,7 @@ struct xen_sysctl_cpu_featureset { * If zero exit with success. */ -#define LIVEPATCH_PAYLOAD_VERSION 1 +#define LIVEPATCH_PAYLOAD_VERSION 2 /* * .livepatch.funcs structure layout defined in the `Payload format` * section in the Live Patch design document. @@ -826,6 +826,11 @@ struct xen_sysctl_cpu_featureset { * We guard this with __XEN__ as toolstacks SHOULD not use it. */ #ifdef __XEN__ +typedef enum livepatch_func_state { + LIVEPATCH_FUNC_NOT_APPLIED = 0, + LIVEPATCH_FUNC_APPLIED = 1 +} livepatch_func_state_t; + struct livepatch_func { const char *name; /* Name of function to be patched. */ void *new_addr; @@ -834,6 +839,10 @@ struct livepatch_func { uint32_t old_size; uint8_t version; /* MUST be LIVEPATCH_PAYLOAD_VERSION. */ uint8_t opaque[31]; +#if defined CONFIG_X86 + uint8_t applied; + uint8_t _pad[7]; +#endif }; typedef struct livepatch_func livepatch_func_t; #endif diff --git a/xen/include/xen/livepatch.h b/xen/include/xen/livepatch.h index 2aec532ee2..a93126f631 100644 --- a/xen/include/xen/livepatch.h +++ b/xen/include/xen/livepatch.h @@ -117,7 +117,7 @@ int arch_livepatch_quiesce(void); void arch_livepatch_revive(void); void arch_livepatch_apply(struct livepatch_func *func); -void arch_livepatch_revert(const struct livepatch_func *func); +void arch_livepatch_revert(struct livepatch_func *func); void arch_livepatch_post_action(void); void arch_livepatch_mask(void);