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 CB67EC433EF for ; Thu, 5 May 2022 13:28:09 +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=MXLb8rHzgoQ1wMHOiSoEAYrEEUOEYntIEQ+DCESfgR0=; b=0+F6Px+8XbBXHmWaIuifgVuEuU TkYHwaxfdjr9u/wwqCw7XFaqt+uflMd1hkE9oyny7HdUZhqF1FligNGI1xG6+xT4u28YOhu7lKXqg WPACo5G9p0BJiRNca+VPpma/iYHYpvbK3ASH+zW6BpVE4/e817LsNmQ1jJmCl0zwmgdoOy78dAI7L baJyYZfFAwCmytzxlxUCpi40yTcY4mLwqw7j95f0h5cEbsgZwcWauvxkZLrt72eWBdCXek8RM+BxN ClYPbVAD4w3JYcbVLHNI7it9S1x7IPL5GLOf2NoTnlm0bjzuTHRS8dnyHOkjOpZEuhmQpTlqCUy51 aP6PLmVA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nmbVb-00G1Qx-CG; Thu, 05 May 2022 13:27:07 +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 1nmbVW-00G1PZ-8C for linux-arm-kernel@lists.infradead.org; Thu, 05 May 2022 13:27:05 +0000 Received: from dggpemm500021.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KvDxP6FS9zhY9w; Thu, 5 May 2022 21:26:33 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500021.china.huawei.com (7.185.36.109) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 5 May 2022 21:26:55 +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; Thu, 5 May 2022 21:26:55 +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> From: "Leizhen (ThunderTown)" Message-ID: Date: Thu, 5 May 2022 21:26:44 +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: dggems701-chm.china.huawei.com (10.3.19.178) 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-20220505_062702_697498_697BDDA9 X-CRM114-Status: GOOD ( 23.96 ) 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 2022/5/5 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. > > ... which should do the right thing even if we repurpose the TPIDRs and move the offset elsewhere. > > As Will says, we should only log this for !user_mode(regs), so it could > be placed in the block below, immediately before we print the kernel PC, i.e. > > if (!user_mode_regs) { > printk("cpu offset : %016lx\n", __my_cpu_offset()); > printk("pc : %pS\n", (void *)regs->pc); > printk("lr : %pS\n", (void *)ptrauth_strip_insn_pac(lr)); > ... > } > > ... or in a separate block which checks the same condition. > > Thanks, > Mark. > >> + >> if (!user_mode(regs)) { >> printk("pc : %pS\n", (void *)regs->pc); >> printk("lr : %pS\n", (void *)ptrauth_strip_insn_pac(lr)); >> -- >> 2.25.1 >> > . > -- Regards, Zhen Lei _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel