From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: [PATCH v2 33/44] ftrace: WARN on rcuidle Date: Mon, 19 Sep 2022 12:00:12 +0200 Message-ID: <20220919101522.573936213@infradead.org> References: <20220919095939.761690562@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Filter: OpenDKIM Filter v2.11.0 smtp4.osuosl.org 9E188425BC DKIM-Filter: OpenDKIM Filter v2.11.0 smtp4.osuosl.org 68A8142540 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org B41276FB85 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org D5F1460BC3 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=d1PXrA0ji5y7WX9aOTLSAuRcBGPwqyEk8vh/reRf4ZE=; b=LWO0au/rvI8XBtiLpmPp+Hj6ty aVN9bB7ygtes6LLRtSeEdagzQF9hUqR0AP2Xlew8lTJ1+l9gYN1fheWby45WO7HUyga7mVz9FhOWt eiKINrvkyp9Bqyk9kjLcHDbPWOp25a01H/raJMCYIgNb4IrTiq9QT/AhVOBh+cjOloRDnZxT+XWaF yLrkkOPgJrBGclK4tPXgrx0gLmayYBzdMjZH7m6HBUXtMXqr3Kpvk05mGoh2fnRJUMQaUjvpUM+T/ ddTH7+6dZSJ3yLO+E1HwSdjEk51sYXwh0pWg9z+JrKcWs/qshJKYcJvb6hFkNZVoCc5bOF2D+D9a1 zFoJmGCw==; List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" To: peterz@infradead.org Cc: juri.lelli@redhat.com, rafael@kernel.org, catalin.marinas@arm.com, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, mpe@ellerman.id.au, chenhuacai@kernel.org, christophe.leroy@csgroup.eu, linux-acpi@vger.kernel.org, agross@kernel.org, geert@linux-m68k.org, linux-imx@nxp.com, vgupta@kernel.org, mattst88@gmail.com, mturquette@baylibre.com, sammy@sammy.net, pmladek@suse.com, linux-pm@vger.kernel.org, Sascha Hauer , linux-um@lists.infradead.org, npiggin@gmail.com, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.com, andreyknvl@gmail.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, senozhatsky@chromium.org, svens@linux.ibm.com, jolsa@kernel.org, tj@kernel.org, Andrew Morton CONFIG_GENERIC_ENTRY disallows any and all tracing when RCU isn't enabled. XXX if s390 (the only other GENERIC_ENTRY user as of this writing) isn't comfortable with this, we could switch to HAVE_NOINSTR_VALIDATION which is x86_64 only atm. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/tracepoint.h | 13 ++++++++++++- kernel/trace/trace.c | 3 +++ 2 files changed, 15 insertions(+), 1 deletion(-) --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -178,6 +178,16 @@ static inline struct tracepoint *tracepo #endif /* CONFIG_HAVE_STATIC_CALL */ /* + * CONFIG_GENERIC_ENTRY archs are expected to have sanitized entry and idle + * code that disallow any/all tracing/instrumentation when RCU isn't watching. + */ +#ifdef CONFIG_GENERIC_ENTRY +#define RCUIDLE_COND(rcuidle) (rcuidle) +#else +#define RCUIDLE_COND(rcuidle) (rcuidle && in_nmi()) +#endif + +/* * it_func[0] is never NULL because there is at least one element in the array * when the array itself is non NULL. */ @@ -189,7 +199,8 @@ static inline struct tracepoint *tracepo return; \ \ /* srcu can't be used from NMI */ \ - WARN_ON_ONCE(rcuidle && in_nmi()); \ + if (WARN_ON_ONCE(RCUIDLE_COND(rcuidle))) \ + return; \ \ /* keep srcu and sched-rcu usage consistent */ \ preempt_disable_notrace(); \ --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3104,6 +3104,9 @@ void __trace_stack(struct trace_array *t return; } + if (WARN_ON_ONCE(IS_ENABLED(CONFIG_GENERIC_ENTRY))) + return; + /* * When an NMI triggers, RCU is enabled via ct_nmi_enter(), * but if the above rcu_is_watching() failed, then the NMI