From patchwork Sun Mar 14 20:34:44 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: 12138005 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 B4F5BC433E0 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 4B15464EB6 for ; Sun, 14 Mar 2021 20:46:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4B15464EB6 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=s/ZP7MIRuZpTEHMIkqS5u05rjkUiojiuZkn8IvhNqC0=; b=ZXn1E7Y2OGtEgP60ZBXxy+3iQ Hve+eyAuBxwfDUPINc0fa3nDnWA7iOVewXohgK66iswaem5BCnVO9UtxcGlnHn+wmzWPRLA/bRpym +OKpyt0H795+8GF8WZU0Qe1jlefGPpdoDi9ygudWUYQEvZQEnbjE2iMirMwgg/uTxf/213z2AZRt6 2i0I2YApQjArKZ9D+Usna3U7PP0MHA4CBvKgABFBbcBg8OL10WpdOZXu8WeyHwDM0TudQGtMWdw/c VPE7HQnWiXnRU9BqUaTIt0JV5eXiZKakA2XhV1GDz6u/Qew49zHOYNi+lI7bmeUUq3FOBthq0FQ+C Sa6w7ib/g==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lLXa9-00EWWe-81; Sun, 14 Mar 2021 20:43:25 +0000 Received: from szxga05-in.huawei.com ([45.249.212.191]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lLXYO-00EWRN-S6 for linux-arm-kernel@lists.infradead.org; Sun, 14 Mar 2021 20:41:46 +0000 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DzBGv4TN1zNmXh; Mon, 15 Mar 2021 04:39:03 +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 04:41:14 +0800 From: Barry Song To: , , CC: , , , , Barry Song Subject: [RESEND PATCH v2 2/2] scripts/gdb: add lx_current support for arm64 Date: Mon, 15 Mar 2021 09:34:44 +1300 Message-ID: <20210314203444.15188-3-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_204139_630475_40C35381 X-CRM114-Status: GOOD ( 14.08 ) 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 arm64 uses SP_EL0 to save the current task_struct address. While running in EL0, SP_EL0 is clobbered by userspace. So if the upper bit is not 1 (not TTBR1), the current address is invalid. This patch checks the upper bit of SP_EL0, if the upper bit is 1, lx_current() of arm64 will return the derefrence of current task. Otherwise, lx_current() will tell users they are running in userspace(EL0). While arm64 is running in EL0, it is actually pointless to print current task as the memory of kernel space is not accessible in EL0. Signed-off-by: Barry Song --- Documentation/dev-tools/gdb-kernel-debugging.rst | 2 +- scripts/gdb/linux/cpus.py | 13 +++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/Documentation/dev-tools/gdb-kernel-debugging.rst b/Documentation/dev-tools/gdb-kernel-debugging.rst index 1586901b683c..8e0f1fe8d17a 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(supported by x86 only):: +- Examine fields of the current task struct(supported by x86 and arm64 only):: (gdb) p $lx_current().pid $1 = 4998 diff --git a/scripts/gdb/linux/cpus.py b/scripts/gdb/linux/cpus.py index f382762509d3..15fc4626d236 100644 --- a/scripts/gdb/linux/cpus.py +++ b/scripts/gdb/linux/cpus.py @@ -16,6 +16,9 @@ import gdb from linux import tasks, utils +task_type = utils.CachedType("struct task_struct") + + MAX_CPUS = 4096 @@ -157,9 +160,19 @@ Note that VAR has to be quoted as string.""" PerCpu() def get_current_task(cpu): + task_ptr_type = task_type.get_type().pointer() + if utils.is_target_arch("x86"): var_ptr = gdb.parse_and_eval("¤t_task") return per_cpu(var_ptr, cpu).dereference() + elif utils.is_target_arch("aarch64"): + current_task_addr = gdb.parse_and_eval("$SP_EL0") + if((current_task_addr >> 63) != 0): + current_task = current_task_addr.cast(task_ptr_type) + return current_task.dereference() + else: + raise gdb.GdbError("Sorry, obtaining the current task is not allowed " + "while running in userspace(EL0)") else: raise gdb.GdbError("Sorry, obtaining the current task is not yet " "supported with this arch")