From patchwork Fri Dec 22 19:36:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 13503750 Received: from smtp-fw-9106.amazon.com (smtp-fw-9106.amazon.com [207.171.188.206]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0916831723; Fri, 22 Dec 2023 19:38:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="eAtqzVKd" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1703273891; x=1734809891; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=qmhUZjf5F0irRMFPH4YUunFpNZODTBv7SKMl/vOJmCU=; b=eAtqzVKdECYu+n2gePGRkHUjztmVDVHbcPLtf8gb+RFjZtC8+G4Dpfe6 YRVmhsqakOEo+kpei26Fh7jKEng1Xf4D3QwFZIXc2nVyWC+QXwDDqjyYa ln91AmDjNGLTNEVTopMPcm1Wr6nAfo0dhJ8M8HM06prJTHCn8y4wHcp5b k=; X-IronPort-AV: E=Sophos;i="6.04,297,1695686400"; d="scan'208";a="692781574" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO email-inbound-relay-pdx-2a-m6i4x-1197e3af.us-west-2.amazon.com) ([10.25.36.210]) by smtp-border-fw-9106.sea19.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Dec 2023 19:38:06 +0000 Received: from smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev (pdx2-ws-svc-p26-lb5-vlan2.pdx.amazon.com [10.39.38.66]) by email-inbound-relay-pdx-2a-m6i4x-1197e3af.us-west-2.amazon.com (Postfix) with ESMTPS id 2C677100395; Fri, 22 Dec 2023 19:38:04 +0000 (UTC) Received: from EX19MTAUWA002.ant.amazon.com [10.0.21.151:8114] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.6.30:2525] with esmtp (Farcaster) id 118258fa-6e62-4bd3-8f88-fab34a1b9f0a; Fri, 22 Dec 2023 19:38:03 +0000 (UTC) X-Farcaster-Flow-ID: 118258fa-6e62-4bd3-8f88-fab34a1b9f0a Received: from EX19D020UWC004.ant.amazon.com (10.13.138.149) by EX19MTAUWA002.ant.amazon.com (10.250.64.202) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Fri, 22 Dec 2023 19:38:02 +0000 Received: from dev-dsk-graf-1a-5ce218e4.eu-west-1.amazon.com (10.253.83.51) by EX19D020UWC004.ant.amazon.com (10.13.138.149) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Fri, 22 Dec 2023 19:37:58 +0000 From: Alexander Graf To: CC: , , , , , , , Eric Biederman , "H. Peter Anvin" , Andy Lutomirski , Peter Zijlstra , "Rob Herring" , Steven Rostedt , "Andrew Morton" , Mark Rutland , "Tom Lendacky" , Ashish Kalra , James Gowans , Stanislav Kinsburskii , , , , Anthony Yznaga , Usama Arif , David Woodhouse , Benjamin Herrenschmidt Subject: [PATCH v2 11/17] tracing: Introduce kho serialization Date: Fri, 22 Dec 2023 19:36:01 +0000 Message-ID: <20231222193607.15474-12-graf@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231222193607.15474-1-graf@amazon.com> References: <20231222193607.15474-1-graf@amazon.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D041UWA004.ant.amazon.com (10.13.139.9) To EX19D020UWC004.ant.amazon.com (10.13.138.149) We want to be able to transfer ftrace state from one kernel to the next. To start off with, let's establish all the boiler plate to get a write hook when KHO wants to serialize and fill out basic data. Follow-up patches will fill in serialization of ring buffers and events. Signed-off-by: Alexander Graf --- v1 -> v2: - Remove ifdefs --- kernel/trace/trace.c | 47 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 199df497db07..6ec31879b4eb 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include @@ -866,6 +867,8 @@ static struct tracer *trace_types __read_mostly; */ DEFINE_MUTEX(trace_types_lock); +static bool trace_in_kho; + /* * serialize the access of the ring buffer * @@ -10560,12 +10563,56 @@ void __init early_trace_init(void) init_events(); } +static int trace_kho_notifier(struct notifier_block *self, + unsigned long cmd, + void *v) +{ + const char compatible[] = "ftrace-v1"; + void *fdt = v; + int err = 0; + + switch (cmd) { + case KEXEC_KHO_ABORT: + if (trace_in_kho) + mutex_unlock(&trace_types_lock); + trace_in_kho = false; + return NOTIFY_DONE; + case KEXEC_KHO_DUMP: + /* Handled below */ + break; + default: + return NOTIFY_BAD; + } + + if (unlikely(tracing_disabled)) + return NOTIFY_DONE; + + err |= fdt_begin_node(fdt, "ftrace"); + err |= fdt_property(fdt, "compatible", compatible, sizeof(compatible)); + err |= fdt_end_node(fdt); + + if (!err) { + /* Hold all future allocations */ + mutex_lock(&trace_types_lock); + trace_in_kho = true; + } + + return err ? NOTIFY_BAD : NOTIFY_DONE; +} + +static struct notifier_block trace_kho_nb = { + .notifier_call = trace_kho_notifier, +}; + void __init trace_init(void) { trace_event_init(); if (boot_instance_index) enable_instances(); + + if (IS_ENABLED(CONFIG_FTRACE_KHO)) + register_kho_notifier(&trace_kho_nb); } __init static void clear_boot_tracer(void)