From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D6D01C433F5 for ; Fri, 6 May 2022 10:23:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:CC:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=AklFb9snk2GwfC19fuDp60TPNMu0c4FrjFbR0BAAHt0=; b=XLr45e1uBkQ+kmDzhk7nV8+Ih/ EP19buz/yPnr73TIPxSbe6S/NVTOxEUJ85VH8Bw0Ke9sbcWyaWcDGm9d6TXc7FwjKm7PJKFTMh+IX yOKMeuE3jZBvtgHvLEvYHhIUgsKmKsZEe5yEup2jsqsmArUwkm3Ps/XnMdNQVkXg/ro/z5DRJzbPh Yd6outwk1bkCDnCA/iARi0/AcIJB22CAIDJRD1/tp0YJxOo3fF7OjDpn+Z9Z9EQiVS4njm6haJYQ6 ESvFIW50ydWlpklL4DP/Quvu8tXWpxzyM9pbdNbV4ng5pE8IgwPTQ/kLgwzRj+zZ28mJW6vdJCEjX 7PBM72Eg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmv60-002fyL-JM; Fri, 06 May 2022 10:22:00 +0000 Received: from szxga01-in.huawei.com ([45.249.212.187]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmv5v-002ft4-In for linux-arm-kernel@lists.infradead.org; Fri, 06 May 2022 10:21:57 +0000 Received: from dggpemm500020.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KvmnL4V3KzhYhJ; Fri, 6 May 2022 18:21:26 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 6 May 2022 18:21:49 +0800 Received: from [10.174.178.55] (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 6 May 2022 18:21:49 +0800 Subject: Re: [PATCH v3] arm64: add the printing of tpidr_elx in __show_regs() To: Mark Rutland CC: Catalin Marinas , Will Deacon , , References: <20220505095640.312-1-thunder.leizhen@huawei.com> <307e4def-1e4a-1110-e644-d485b9959ab1@huawei.com> <7c1207fa-56aa-1b33-31fd-3ec395b08f2b@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: Date: Fri, 6 May 2022 18:21:37 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220506_032156_009354_4E5C7C3A X-CRM114-Status: GOOD ( 17.78 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2022/5/6 18:09, Mark Rutland wrote: > On Fri, May 06, 2022 at 04:16:55PM +0800, Leizhen (ThunderTown) wrote: >> >> >> On 2022/5/5 21:34, Leizhen (ThunderTown) wrote: >>> On 2022/5/5 21:26, Leizhen (ThunderTown) wrote: >>>> On 2022/5/5 21:04, Mark Rutland wrote: >>>>> On Thu, May 05, 2022 at 05:56:40PM +0800, Zhen Lei wrote: >>>>>> Commit 7158627686f0 ("arm64: percpu: implement optimised pcpu access >>>>>> using tpidr_el1") and commit 6d99b68933fb ("arm64: alternatives: use >>>>>> tpidr_el2 on VHE hosts") use tpidr_elx to cache my_cpu_offset to optimize >>>>>> pcpu access. However, when performing reverse execution based on the >>>>>> registers and the memory contents in kdump, this information is sometimes >>>>>> required if there is a pcpu access. >>>>>> >>>>>> Signed-off-by: Zhen Lei >>>>>> --- >>>>>> arch/arm64/kernel/process.c | 5 +++++ >>>>>> 1 file changed, 5 insertions(+) >>>>>> >>>>>> v2 --> v3: >>>>>> 1) Relace "switch (read_sysreg(CurrentEL))" statement with >>>>>> "if (is_kernel_in_hyp_mode())" statement. >>>>>> 2) Change the register name to lowercase. >>>>>> >>>>>> v1 --> v2: >>>>>> Directly print the tpidr_elx register of the current exception level. >>>>>> Avoid coupling with the implementation of 'my_cpu_offset'. >>>>>> >>>>>> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c >>>>>> index 7fa97df55e3ad3f..7b6bccce9721c36 100644 >>>>>> --- a/arch/arm64/kernel/process.c >>>>>> +++ b/arch/arm64/kernel/process.c >>>>>> @@ -216,6 +216,11 @@ void __show_regs(struct pt_regs *regs) >>>>>> show_regs_print_info(KERN_DEFAULT); >>>>>> print_pstate(regs); >>>>>> >>>>>> + if (is_kernel_in_hyp_mode()) >>>>>> + printk("tpidr_el2 : %016llx\n", read_sysreg(tpidr_el2)); >>>>>> + else >>>>>> + printk("tpidr_el1 : %016llx\n", read_sysreg(tpidr_el1)); >>>>> >>>>> If we care about the offset specifically, this would be simpler as: >>>>> >>>>> printk("cpu offset : 0x%016lx\n", __my_cpu_offset()); >>>> >>>> The function name is __show_regs(), so not using register name may not be good. >>>> In fact, some other architectures may also have this problem. If we use my_cpu_offset, >>>> we may need to put it in a public. >>> >>> The other idea is to back up each my_cpu_offset in an array. In this way, the offset can >>> be queried through vmcore even if it is not printed. >> >> Sorry, __per_cpu_offset[NR_CPUS] is always defined. > > Surely that's in the vmcore already? It's just data in memory. Yes. There is also a definition in drivers/base/arch_numa.c. I didn't search the drivers directory at first. I thought there would be no definition when CONFIG_HAVE_SETUP_PER_CPU_AREA=y. crash> p -x __per_cpu_offset __per_cpu_offset = $1 = {0xffff8003f460d000, 0xffff8003f4621000, 0xffff8003f4635000, 0xffff8003f4649000 > > Thanks, > Mark. > . > -- Regards, Zhen Lei _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel