From patchwork Sun Mar 14 20:34:43 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: 12138003 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=-17.0 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=unavailable 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 B29F1C433E6 for ; Sun, 14 Mar 2021 20:46:17 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 48F8864E89 for ; Sun, 14 Mar 2021 20:46:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 48F8864E89 Authentication-Results: mail.kernel.org; dmarc=fail (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=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-ID:Date: Subject:CC: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=bqHeLKIoDx+4gC/4aufXciUdT Y/i5mADJ7zTphJ+sm+6st3yL3FTh5H9Qi8nQzOc28TDwJbUxhUyK5262X6uh69Lvglh/fGRb13c13 VFO4WAYYoChTVF9IKQZ6ctVtmlF0McDeOxc6Sp4NOhxjoe1nTP8T9x8tZexp9ijxs6+ifryynEvuk gxt+wHYMIz8GfrxYkixX1mNVOGpkrMWgOS50T6wjqkmx6WECP2M2YtbuYNimnru/cXGKqJc0dpkBj 5todmh5NAHZmgLN9Y72800gKVTFs4rgzfwiKRqJuSK0R2xymiIXVYQ0QiwRsem2648vlmg5gRyHta rGMhMyGRA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lLXa1-00EWVw-8i; Sun, 14 Mar 2021 20:43:18 +0000 Received: from szxga06-in.huawei.com ([45.249.212.32]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lLXYO-00EWRI-63 for linux-arm-kernel@lists.infradead.org; Sun, 14 Mar 2021 20:41:46 +0000 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4DzBHn3yrSzjVMF; Mon, 15 Mar 2021 04:39:49 +0800 (CST) Received: from SWX921481.china.huawei.com (10.126.202.142) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.498.0; Mon, 15 Mar 2021 04:41:12 +0800 From: Barry Song To: , , CC: , , , , Barry Song Subject: [RESEND PATCH v2 1/2] scripts/gdb: document lx_current is only supported by x86 Date: Mon, 15 Mar 2021 09:34:43 +1300 Message-ID: <20210314203444.15188-2-song.bao.hua@hisilicon.com> X-Mailer: git-send-email 2.21.0.windows.1 In-Reply-To: <20210314203444.15188-1-song.bao.hua@hisilicon.com> References: <20210314203444.15188-1-song.bao.hua@hisilicon.com> MIME-Version: 1.0 X-Originating-IP: [10.126.202.142] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210314_204138_768894_850746AD X-CRM114-Status: UNSURE ( 9.62 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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()