From patchwork Tue Feb 23 22:25:39 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Song Bao Hua (Barry Song)" X-Patchwork-Id: 12100991 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=-16.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 ECF2BC433DB for ; Tue, 23 Feb 2021 22:33:18 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9E63361493 for ; Tue, 23 Feb 2021 22:33:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E63361493 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=hisilicon.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-ID:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=mxcthLyc3oaUNCNL3mgE/6SJ0FaPXQYqX7NBSjzGXEg=; b=OTzyuTfxE2f5Lw+Ob68105BUj C7ydcvjudrDVZV1WIbS1b85IPttcbOvgZSjoIwfX91PyrFpOj7nCEIxyO2Ql9QvE+xDeWqWOH8spf 0MeCla2JtkIn97I4vksGzQzHFCc35ksP3BpMo+KTm3CSKqmJfDV+aehoxTz8jCySyUT7cNucILHVx +RSM+16Rve5Sq9MTceKn9FdwfOa7JrXuMqf9BM6ZPp8cQnN47hGeM3e8+WyCuCcLgmnO5hJW/9ZFw YzkeSL2TTiPFEszCjL2bjp9IbRpR0fivpINIEkLzpQW07aPgexKYGcz0BPBHyjgCjNbVMr0bZS0U7 L/OteAU3Q==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lEgDs-0004f5-Ul; Tue, 23 Feb 2021 22:32:04 +0000 Received: from szxga04-in.huawei.com ([45.249.212.190]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1lEgDn-0004e4-O8 for linux-arm-kernel@lists.infradead.org; Tue, 23 Feb 2021 22:32:01 +0000 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4DlYf45rR7z16Bs5; Wed, 24 Feb 2021 06:30:20 +0800 (CST) Received: from SWX921481.china.huawei.com (10.126.200.133) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.498.0; Wed, 24 Feb 2021 06:31:46 +0800 From: Barry Song To: , , , Subject: [PATCH v2 1/2] scripts/gdb: document lx_current is only supported by x86 Date: Wed, 24 Feb 2021 11:25:39 +1300 Message-ID: <20210223222540.9120-2-song.bao.hua@hisilicon.com> X-Mailer: git-send-email 2.21.0.windows.1 In-Reply-To: <20210223222540.9120-1-song.bao.hua@hisilicon.com> References: <20210223222540.9120-1-song.bao.hua@hisilicon.com> MIME-Version: 1.0 X-Originating-IP: [10.126.200.133] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210223_173200_099455_37666AE6 X-CRM114-Status: GOOD ( 10.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Barry Song , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxarm@openeuler.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org x86 is the only architecture which has per_cpu current_task: arch$ git grep current_task | grep -i per_cpu x86/include/asm/current.h:DECLARE_PER_CPU(struct task_struct *, current_task); x86/kernel/cpu/common.c:DEFINE_PER_CPU(struct task_struct *, current_task) ____cacheline_aligned = x86/kernel/cpu/common.c:EXPORT_PER_CPU_SYMBOL(current_task); x86/kernel/cpu/common.c:DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; x86/kernel/cpu/common.c:EXPORT_PER_CPU_SYMBOL(current_task); x86/kernel/smpboot.c: per_cpu(current_task, cpu) = idle; On other architectures, lx_current() will lead to a python exception: (gdb) p $lx_current().pid Python Exception No symbol "current_task" in current context.: Error occurred in Python: No symbol "current_task" in current context. To avoid more people struggling and wasting time in other architectures, document it. Cc: Jan Kiszka Signed-off-by: Barry Song --- Documentation/dev-tools/gdb-kernel-debugging.rst | 2 +- scripts/gdb/linux/cpus.py | 10 ++++++++-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/Documentation/dev-tools/gdb-kernel-debugging.rst b/Documentation/dev-tools/gdb-kernel-debugging.rst index 4756f6b3a04e..1586901b683c 100644 --- a/Documentation/dev-tools/gdb-kernel-debugging.rst +++ b/Documentation/dev-tools/gdb-kernel-debugging.rst @@ -114,7 +114,7 @@ Examples of using the Linux-provided gdb helpers [ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved .... -- Examine fields of the current task struct:: +- Examine fields of the current task struct(supported by x86 only):: (gdb) p $lx_current().pid $1 = 4998 diff --git a/scripts/gdb/linux/cpus.py b/scripts/gdb/linux/cpus.py index 008e62f3190d..f382762509d3 100644 --- a/scripts/gdb/linux/cpus.py +++ b/scripts/gdb/linux/cpus.py @@ -156,6 +156,13 @@ Note that VAR has to be quoted as string.""" PerCpu() +def get_current_task(cpu): + if utils.is_target_arch("x86"): + var_ptr = gdb.parse_and_eval("¤t_task") + return per_cpu(var_ptr, cpu).dereference() + else: + raise gdb.GdbError("Sorry, obtaining the current task is not yet " + "supported with this arch") class LxCurrentFunc(gdb.Function): """Return current task. @@ -167,8 +174,7 @@ number. If CPU is omitted, the CPU of the current context is used.""" super(LxCurrentFunc, self).__init__("lx_current") def invoke(self, cpu=-1): - var_ptr = gdb.parse_and_eval("¤t_task") - return per_cpu(var_ptr, cpu).dereference() + return get_current_task(cpu) LxCurrentFunc()