From patchwork Wed Dec 13 00:04:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 13490183 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="a1vPSAn4" Received: from smtp-fw-52005.amazon.com (smtp-fw-52005.amazon.com [52.119.213.156]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70463D4D; Tue, 12 Dec 2023 16:08:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1702426083; x=1733962083; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=8E5gYeBn7LzFXeE9t3+WWJhfPWwonViYFj973oiYUIk=; b=a1vPSAn4RN5MYIpsd3DyyRCkJuBHnCOBZooVN6/fJapR6P9VnnkYiZDS 1vd8AU/P7+v6f0O8Dzt4xCJuMNWr6H27HNgYhSjG9x5NzAiItEAdByflx 5JxfSMdqz0mSchn+8natHOk8lS7fixALyrIXy89rim6IuNE5YAMbj/jnk 0=; X-IronPort-AV: E=Sophos;i="6.04,271,1695686400"; d="scan'208";a="621371857" Received: from iad12-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-iad-1a-m6i4x-bbc6e425.us-east-1.amazon.com) ([10.43.8.6]) by smtp-border-fw-52005.iad7.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Dec 2023 00:08:01 +0000 Received: from smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev (iad7-ws-svc-p70-lb3-vlan3.iad.amazon.com [10.32.235.38]) by email-inbound-relay-iad-1a-m6i4x-bbc6e425.us-east-1.amazon.com (Postfix) with ESMTPS id EF61380632; Wed, 13 Dec 2023 00:07:52 +0000 (UTC) Received: from EX19MTAUWB001.ant.amazon.com [10.0.21.151:16104] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.43.236:2525] with esmtp (Farcaster) id 3bda4ab2-5ec6-4d32-90c9-2880fbf14c72; Wed, 13 Dec 2023 00:07:51 +0000 (UTC) X-Farcaster-Flow-ID: 3bda4ab2-5ec6-4d32-90c9-2880fbf14c72 Received: from EX19D020UWC004.ant.amazon.com (10.13.138.149) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Wed, 13 Dec 2023 00:07:44 +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; Wed, 13 Dec 2023 00:07:40 +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 15/15] tracing: Add config option for kexec handover Date: Wed, 13 Dec 2023 00:04:52 +0000 Message-ID: <20231213000452.88295-16-graf@amazon.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231213000452.88295-1-graf@amazon.com> References: <20231213000452.88295-1-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: EX19D033UWA001.ant.amazon.com (10.13.139.103) To EX19D020UWC004.ant.amazon.com (10.13.138.149) Now that all bits are in place to allow ftrace to pass its trace data into the next kernel on kexec, let's give users a kconfig option to enable the functionality. Signed-off-by: Alexander Graf --- kernel/trace/Kconfig | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 61c541c36596..af83ee755b9e 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -1169,6 +1169,19 @@ config HIST_TRIGGERS_DEBUG If unsure, say N. +config FTRACE_KHO + bool "Ftrace Kexec handover support" + depends on KEXEC_KHO + help + Enable support for ftrace to pass metadata across kexec so the new + kernel continues to use the previous kernel's trace buffers. + + This can be useful when debugging kexec performance or correctness + issues: The new kernel can dump the old kernel's trace buffer which + contains all events until reboot. + + If unsure, say N. + source "kernel/trace/rv/Kconfig" endif # FTRACE