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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 C6E20C55179 for ; Sun, 8 Nov 2020 04:29:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9809B2220B for ; Sun, 8 Nov 2020 04:29:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728179AbgKHE3r (ORCPT ); Sat, 7 Nov 2020 23:29:47 -0500 Received: from mga14.intel.com ([192.55.52.115]:27415 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726470AbgKHE3k (ORCPT ); Sat, 7 Nov 2020 23:29:40 -0500 IronPort-SDR: KawCsgepVkI03elTuydDxV8/yvjenMc+U1UOhyRPNSRqwN1PLj+GaQJ89rzOiOL/wIOohtg9kB 66UxDpG5zc9g== X-IronPort-AV: E=McAfee;i="6000,8403,9798"; a="168900975" X-IronPort-AV: E=Sophos;i="5.77,460,1596524400"; d="scan'208";a="168900975" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Nov 2020 20:29:38 -0800 IronPort-SDR: tL8fIEbpN2uf3nCT+Cm64Lh3sWbu414WoH6KPGvBhlY1H55mtfNHNEBdbAjwoANA5qmcTrOsXW 6weLOFlZ0Ybg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,460,1596524400"; d="scan'208";a="307244987" Received: from otcwcpicx6.sc.intel.com ([172.25.55.29]) by fmsmga008.fm.intel.com with ESMTP; 07 Nov 2020 20:29:38 -0800 From: Fenghua Yu To: "Borislav Petkov" , "Thomas Gleixner" , "Ingo Molnar" , "Peter Zijlstra" , "Tony Luck" , "Randy Dunlap" , "Xiaoyao Li " , "Ravi V Shankar" Cc: "linux-kernel" , "x86" , Fenghua Yu Subject: [PATCH 3/4] x86/bus_lock: Set rate limit for bus lock Date: Sun, 8 Nov 2020 04:29:17 +0000 Message-Id: <20201108042918.1011889-4-fenghua.yu@intel.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201108042918.1011889-1-fenghua.yu@intel.com> References: <20201108042918.1011889-1-fenghua.yu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org To enforce user application throttling or mitigations, extend the existing split lock detect kernel parameter: split_lock_detect=ratelimit:N It limits bus lock rate to N per second for non-root users. Signed-off-by: Fenghua Yu Reviewed-by: Tony Luck --- arch/x86/kernel/cpu/intel.c | 37 ++++++++++++++++++++++++++++++++----- include/linux/sched/user.h | 4 +++- kernel/user.c | 7 +++++++ 3 files changed, 42 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 4c8a22c36798..9d33fc9295ea 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -10,6 +10,9 @@ #include #include #include +#include +#include +#include #include #include @@ -40,6 +43,7 @@ enum split_lock_detect_state { sld_off = 0, sld_warn, sld_fatal, + sld_ratelimit, }; /* @@ -998,13 +1002,25 @@ static const struct { { "off", sld_off }, { "warn", sld_warn }, { "fatal", sld_fatal }, + { "ratelimit:", sld_ratelimit }, }; static inline bool match_option(const char *arg, int arglen, const char *opt) { - int len = strlen(opt); - return len == arglen && !strncmp(arg, opt, len); + int len = strlen(opt), ratelimit; + + if (strncmp(arg, opt, len)) + return false; + + if (sscanf(arg, "ratelimit:%d", &ratelimit) == 1 && ratelimit > 0 && + ratelimit_bl <= HZ / 2) { + ratelimit_bl = ratelimit; + + return true; + } + + return len == arglen; } static bool split_lock_verify_msr(bool on) @@ -1085,10 +1101,10 @@ static void sld_update_msr(bool on) static void split_lock_init(void) { /* - * If supported, #DB for bus lock will handle warn + * If supported, #DB for bus lock will handle warn or ratelimit * and #AC for split lock is disabled. */ - if (bld && sld_state == sld_warn) { + if ((bld && sld_state == sld_warn) || sld_state == sld_ratelimit) { split_lock_verify_msr(false); return; } @@ -1149,7 +1165,8 @@ static void bus_lock_init(void) bool handle_user_split_lock(struct pt_regs *regs, long error_code) { - if ((regs->flags & X86_EFLAGS_AC) || !sld || sld_state == sld_fatal) + if ((regs->flags & X86_EFLAGS_AC) || !sld || sld_state == sld_fatal || + sld_state == sld_ratelimit) return false; split_lock_warn(regs->ip); return true; @@ -1162,6 +1179,11 @@ void handle_bus_lock(struct pt_regs *regs) pr_warn_ratelimited("#DB: %s/%d took a bus_lock trap at address: 0x%lx\n", current->comm, current->pid, regs->ip); + + if (sld_state == sld_ratelimit) { + while (!__ratelimit(&get_current_user()->ratelimit_bl)) + msleep(1000 / ratelimit_bl); + } } /* @@ -1256,6 +1278,11 @@ static void sld_state_show(void) else pr_info("#DB: sending SIGBUS on user-space bus_locks\n"); break; + + case sld_ratelimit: + if (bld) + pr_info("#DB: setting rate limit to %d/sec per user on non-root user-space bus_locks\n", ratelimit_bl); + break; } } diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h index a8ec3b6093fc..79f95002a123 100644 --- a/include/linux/sched/user.h +++ b/include/linux/sched/user.h @@ -40,8 +40,9 @@ struct user_struct { atomic_t nr_watches; /* The number of watches this user currently has */ #endif - /* Miscellaneous per-user rate limit */ + /* Miscellaneous per-user rate limits */ struct ratelimit_state ratelimit; + struct ratelimit_state ratelimit_bl; }; extern int uids_sysfs_init(void); @@ -51,6 +52,7 @@ extern struct user_struct *find_user(kuid_t); extern struct user_struct root_user; #define INIT_USER (&root_user) +extern int ratelimit_bl; /* per-UID process charging. */ extern struct user_struct * alloc_uid(kuid_t); diff --git a/kernel/user.c b/kernel/user.c index b1635d94a1f2..8fc19706bc91 100644 --- a/kernel/user.c +++ b/kernel/user.c @@ -103,6 +103,7 @@ struct user_struct root_user = { .locked_shm = 0, .uid = GLOBAL_ROOT_UID, .ratelimit = RATELIMIT_STATE_INIT(root_user.ratelimit, 0, 0), + .ratelimit_bl = RATELIMIT_STATE_INIT(root_user.ratelimit_bl, 0, 0), }; /* @@ -172,6 +173,9 @@ void free_uid(struct user_struct *up) free_user(up, flags); } +/* Architectures (e.g. X86) may set this for rate-limited bus locks. */ +int ratelimit_bl; + struct user_struct *alloc_uid(kuid_t uid) { struct hlist_head *hashent = uidhashentry(uid); @@ -190,6 +194,9 @@ struct user_struct *alloc_uid(kuid_t uid) refcount_set(&new->__count, 1); ratelimit_state_init(&new->ratelimit, HZ, 100); ratelimit_set_flags(&new->ratelimit, RATELIMIT_MSG_ON_RELEASE); + ratelimit_state_init(&new->ratelimit_bl, HZ, ratelimit_bl); + ratelimit_set_flags(&new->ratelimit_bl, + RATELIMIT_MSG_ON_RELEASE); /* * Before adding this, check whether we raced -- 2.29.2