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 23FADC433EF for ; Thu, 28 Apr 2022 13:14:21 +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:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=dW+COin5kWsVPfnXWtu7rSkbJVLFH2wReVZlEvp8KeI=; b=Btx5uIw+9QFR5A qorTLsMykwGzTxHgWZhKBXffiwHt/iKetP/Q7p73p/NtfZnH+xMhx3jD4loLE5HdR1Wj+9rc30NT9 YrGfqecWoaoqMZ3QMKExNLUs9SpHSKCZ37i5kD+ysTSMK6uxhaSS+nZyA34V8R82Kzqkl4GK2p0TZ yqKyFH0kmKvpyJmoLiwtNGFN6jixNCi3bpCwDub9+J6Wg6fGLwUag2T2PsAewFWG0hefM4myeZIEA Nr+Z2ePQ57cw5U3B3ZRoAlO93+KFSu4qiUrBsg4WH6dw3wkPLdupCvuT/QYjuWDjCETi8DD4hI9Ql QHu7R6ScYNVtWch9b2gg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nk3xH-006wQC-RY; Thu, 28 Apr 2022 13:13:11 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nk3xD-006wPR-Vq for linux-arm-kernel@lists.infradead.org; Thu, 28 Apr 2022 13:13:09 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 45888B82C98; Thu, 28 Apr 2022 13:13:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8FE1C385A0; Thu, 28 Apr 2022 13:13:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1651151585; bh=u3Cve7iEq9Aj7tMuCV9JVcMUOZZm1kbZE8quTsQa4u8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=B3PbyFYlU3uZY/nMO/NJe/6XHGak3exrygvMRrqszVawor0oulWyVXi2UNTJ2ElHg a/82QXDjnA0wfmZDaYYH/ft58BDYgpZQL3RMqm6YiaO69Opc821hU3sKCwYHNPrBk9 F76VVMK7VC/r/TYaPnaV7aBrf74cvhhadQeU+EKDG20yjfBtDN4IyoJYd1z5XEoO76 biNody94i6V/0SnEeWBUwm55nRkgMfaD6nHiS2w9BXxgLszBwB5TIdH04kFxXshPhk Pggm4q7rCUgne83T/UkVBH4Wg7uyYf3nLtLFsbwDuRktHoXIbW9d6GvGauqeFWAhom u96xh/SeGfR9Q== Date: Thu, 28 Apr 2022 14:13:00 +0100 From: Will Deacon To: "Leizhen (ThunderTown)" Cc: Catalin Marinas , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, James Morse Subject: Re: [PATCH v2] arm64: add the printing of tpidr_elx in __show_regs() Message-ID: <20220428131259.GA14810@willie-the-truck> References: <20220316062408.1113-1-thunder.leizhen@huawei.com> <20220428102156.GA14123@willie-the-truck> <4c956c17-6e13-37a1-7da3-b2c8243c2c01@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220428_061308_367184_24E65866 X-CRM114-Status: GOOD ( 26.42 ) 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 Thu, Apr 28, 2022 at 08:03:50PM +0800, Leizhen (ThunderTown) wrote: > > > On 2022/4/28 19:07, Leizhen (ThunderTown) wrote: > > > > > > On 2022/4/28 18:21, Will Deacon wrote: > >> On Wed, Mar 16, 2022 at 02:24:08PM +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 | 11 +++++++++++ > >>> 1 file changed, 11 insertions(+) > >>> > >>> 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 5369e649fa79ff8..738932e6fa4e947 100644 > >>> --- a/arch/arm64/kernel/process.c > >>> +++ b/arch/arm64/kernel/process.c > >>> @@ -216,6 +216,17 @@ void __show_regs(struct pt_regs *regs) > >>> show_regs_print_info(KERN_DEFAULT); > >>> print_pstate(regs); > >>> > >>> + switch (read_sysreg(CurrentEL)) { > >> > >> This should use is_kernel_in_hyp_mode() to detect if we're running at El2. > > static inline bool is_kernel_in_hyp_mode(void) > { > return read_sysreg(CurrentEL) == CurrentEL_EL2; > } > > I think it's more intuitive to use "switch (read_sysreg(CurrentEL))". No, I disagree with you here, sorry. > >>> + case CurrentEL_EL1: > >>> + printk("tpidr_el1 : %016llx\n", read_sysreg(TPIDR_EL1)); > >>> + break; > >>> + case CurrentEL_EL2: > >>> + printk("tpidr_el2 : %016llx\n", read_sysreg(TPIDR_EL2)); > >>> + break; > >>> + default: > >>> + break; > >>> + } > >> > >> I think this path can be triggered directly from usermode, so we really > >> shouldn't be printing raw kernel virtual addresses here. > > > > I run echo c > /proc/sysrq-trigger and didn't trigger this path, but maybe > > there's another way. Analysis from the other side, except for the instruction > > address, all generic registers r0-r31 is output as raw. There's also an > > opportunity to contain the instruction address. > > On second thought, there seemed to be nothing wrong with it. The user need > to have capable() first. Then the address of the perpcu memory is not static, > the memory is dynamically allocated, exposing it is no different than exposing sp. If show_unhandled_signals is set, then I think any fatal signal takes this path, no? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel