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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 2065DC10F25 for ; Mon, 9 Mar 2020 19:04:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC49920873 for ; Mon, 9 Mar 2020 19:04:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583780672; bh=grI5p9vqb5D3cnYkJYXdP3wmrE6TVPB+3aROxnS7IqY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Po2Xk8vie8gfSX9gDpKhDIgnHGD8Nm+4JYBNJoe+Kwaa4XtNv5w0eltH87HUe7yO4 7JBWPoka0DdjgKrV5Hvb9o6tgKTNkwIoZ+Nzm4+9bhL1wDRzdN5jQkZ9ke1Y2grEqm X1o2nWZar5dBeCoO5rvSYfcva0oxlTaqg9ZjQFmw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727674AbgCITEb (ORCPT ); Mon, 9 Mar 2020 15:04:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:47812 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727579AbgCITE3 (ORCPT ); Mon, 9 Mar 2020 15:04:29 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9A1CA22525; Mon, 9 Mar 2020 19:04:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583780668; bh=grI5p9vqb5D3cnYkJYXdP3wmrE6TVPB+3aROxnS7IqY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pDsVVlZ+BzS2agPgXttEJ4oLGVIks8Tl5rUFigSP4Iz5dzZQvsrKihbzetSBrx+rI pr2v9LCZ+WDhx7RaIcUXFaUPpfuoer4JDNj1xZ6Z+F/KaWAS23eSG78QwpZuowS/DD zrUNWRc+pJbdV0ulSuF+GvY3+Ab7GbCLJcUa0ClE= From: paulmck@kernel.org To: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, kernel-team@fb.com, mingo@kernel.org Cc: elver@google.com, andreyknvl@google.com, glider@google.com, dvyukov@google.com, cai@lca.pw, boqun.feng@gmail.com, "Paul E . McKenney" , Steven Rostedt Subject: [PATCH kcsan 26/32] kcsan, trace: Make KCSAN compatible with tracing Date: Mon, 9 Mar 2020 12:04:14 -0700 Message-Id: <20200309190420.6100-26-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200309190359.GA5822@paulmck-ThinkPad-P72> References: <20200309190359.GA5822@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marco Elver Previously the system would lock up if ftrace was enabled together with KCSAN. This is due to recursion on reporting if the tracer code is instrumented with KCSAN. To avoid this for all types of tracing, disable KCSAN instrumentation for all of kernel/trace. Furthermore, since KCSAN relies on udelay() to introduce delay, we have to disable ftrace for udelay() (currently done for x86) in case KCSAN is used together with lockdep and ftrace. The reason is that it may corrupt lockdep IRQ flags tracing state due to a peculiar case of recursion (details in Makefile comment). Signed-off-by: Marco Elver Reported-by: Qian Cai Cc: Paul E. McKenney Cc: Steven Rostedt Signed-off-by: Paul E. McKenney Tested-by: Qian Cai --- arch/x86/lib/Makefile | 5 +++++ kernel/kcsan/Makefile | 2 ++ kernel/trace/Makefile | 3 +++ 3 files changed, 10 insertions(+) diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile index 432a077..6110bce7 100644 --- a/arch/x86/lib/Makefile +++ b/arch/x86/lib/Makefile @@ -8,6 +8,11 @@ KCOV_INSTRUMENT_delay.o := n # KCSAN uses udelay for introducing watchpoint delay; avoid recursion. KCSAN_SANITIZE_delay.o := n +ifdef CONFIG_KCSAN +# In case KCSAN+lockdep+ftrace are enabled, disable ftrace for delay.o to avoid +# lockdep -> [other libs] -> KCSAN -> udelay -> ftrace -> lockdep recursion. +CFLAGS_REMOVE_delay.o = $(CC_FLAGS_FTRACE) +endif # Early boot use of cmdline; don't instrument it ifdef CONFIG_AMD_MEM_ENCRYPT diff --git a/kernel/kcsan/Makefile b/kernel/kcsan/Makefile index df6b779..d4999b3 100644 --- a/kernel/kcsan/Makefile +++ b/kernel/kcsan/Makefile @@ -4,6 +4,8 @@ KCOV_INSTRUMENT := n UBSAN_SANITIZE := n CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_debugfs.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE) CFLAGS_core.o := $(call cc-option,-fno-conserve-stack,) \ $(call cc-option,-fno-stack-protector,) diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 0e63db6..9072486 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -6,6 +6,9 @@ ifdef CONFIG_FUNCTION_TRACER ORIG_CFLAGS := $(KBUILD_CFLAGS) KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS)) +# Avoid recursion due to instrumentation. +KCSAN_SANITIZE := n + ifdef CONFIG_FTRACE_SELFTEST # selftest needs instrumentation CFLAGS_trace_selftest_dynamic.o = $(CC_FLAGS_FTRACE) -- 2.9.5