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 X-Spam-Level: X-Spam-Status: No, score=-6.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 402ACC4363D for ; Wed, 23 Sep 2020 07:08:52 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 A982C235FC for ; Wed, 23 Sep 2020 07:08:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Xb9KBiXv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A982C235FC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.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=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=YduZaVnqMYVQh5syH3ehY458dExWCYK+sJpz61GgTLo=; b=Xb9KBiXvNmK3iLIB7fwf1McIG qB6oDJd6z+EhPwOlxnz1MsQBBXM6Dpaq/lgSQ0y1n3jIpXPWXLwxVOAarnnn/SuLl7dFBo+6fbEsw ALKP/biK9AW8gYoXu9W0c4U03MMhl58gZICTO6ulMDGgTBA8Bena2yVAddqbizc3CtguFJ6IIs7/M h8mK3lVAaoUgy0PtFEQC1bBdRD3csU8WBQ+YTdKQqQnIpsoyoD4e9tsfcS6xT9p0nWKBG6zFm/Eyc x5d6a9mSTy78xOE8W3icHCFgG+MPiBbDzB+8NoYvxYcOg/bpKJNIeubwHsFHoflALAFRdN+crT9iq 2yJFlaw8g==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kKys1-0003TB-Rm; Wed, 23 Sep 2020 07:07:17 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kKyry-0003Sd-Jr for linux-arm-kernel@lists.infradead.org; Wed, 23 Sep 2020 07:07:15 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 43B6F113E; Wed, 23 Sep 2020 00:07:10 -0700 (PDT) Received: from [10.57.14.157] (unknown [10.57.14.157]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 265D63F70D; Wed, 23 Sep 2020 00:07:07 -0700 (PDT) Subject: Re: [PATCH 6/6] kselftest/arm64: Check mte tagged user address in kernel To: Catalin Marinas References: <20200901092719.9918-1-amit.kachhap@arm.com> <20200901092719.9918-7-amit.kachhap@arm.com> <20200922104123.GF15643@gaia> From: Amit Kachhap Message-ID: Date: Wed, 23 Sep 2020 12:36:59 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200922104123.GF15643@gaia> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200923_030714_747133_B36F8FB7 X-CRM114-Status: GOOD ( 26.21 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Shuah Khan , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Vincenzo Frascino , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 9/22/20 4:11 PM, Catalin Marinas wrote: > On Tue, Sep 01, 2020 at 02:57:19PM +0530, Amit Daniel Kachhap wrote: >> Add a testcase to check that user address with valid/invalid >> mte tag works in kernel mode. This test verifies the kernel API's >> __arch_copy_from_user/__arch_copy_to_user works by considering >> if the user pointer has valid/invalid allocation tags. >> >> In MTE sync mode a SIGSEV fault is generated if a user memory >> with invalid tag is accessed in kernel. In async mode no such >> fault occurs. > > We don't generate a SIGSEGV for faults in the uaccess routines. The > kernel simply returns less copied bytes than what was requested or -1 > and setting errno. ok. I will update in the next iteration. > > BTW, Qemu has a bug and it reports the wrong exception class (lower > DABT) for a tag check fault while in the uaccess routines, leading to > kernel panic (bad mode in synchronous abort handler). Yes I am also seeing this. > >> +static int check_usermem_access_fault(int mem_type, int mode, int mapping) >> +{ >> + int fd, ret, i, err; >> + char val = 'A'; >> + size_t len, read_len; >> + void *ptr, *ptr_next; >> + bool fault; >> + >> + len = 2 * page_sz; >> + err = KSFT_FAIL; >> + /* >> + * Accessing user memory in kernel with invalid tag should fault in sync >> + * mode but may not fault in async mode as per the implemented MTE >> + * support in Arm64 kernel. >> + */ >> + if (mode == MTE_ASYNC_ERR) >> + fault = false; >> + else >> + fault = true; >> + mte_switch_mode(mode, MTE_ALLOW_NON_ZERO_TAG); >> + fd = create_temp_file(); >> + if (fd == -1) >> + return KSFT_FAIL; >> + for (i = 0; i < len; i++) >> + write(fd, &val, sizeof(val)); >> + lseek(fd, 0, 0); >> + ptr = mte_allocate_memory(len, mem_type, mapping, true); >> + if (check_allocated_memory(ptr, len, mem_type, true) != KSFT_PASS) { >> + close(fd); >> + return KSFT_FAIL; >> + } >> + mte_initialize_current_context(mode, (uintptr_t)ptr, len); >> + /* Copy from file into buffer with valid tag */ >> + read_len = read(fd, ptr, len); >> + ret = errno; > > My reading of the man page is that errno is set only if read() returns > -1. Yes. The checks should be optimized here. > >> + mte_wait_after_trig(); >> + if ((cur_mte_cxt.fault_valid == true) || ret == EFAULT || read_len < len) >> + goto usermem_acc_err; >> + /* Verify same pattern is read */ >> + for (i = 0; i < len; i++) >> + if (*(char *)(ptr + i) != val) >> + break; >> + if (i < len) >> + goto usermem_acc_err; >> + >> + /* Tag the next half of memory with different value */ >> + ptr_next = (void *)((unsigned long)ptr + page_sz); >> + ptr_next = mte_insert_tags(ptr_next, page_sz); >> + if (!ptr_next) >> + goto usermem_acc_err; >> + lseek(fd, 0, 0); >> + /* Copy from file into buffer with invalid tag */ >> + read_len = read(fd, ptr, len); >> + ret = errno; >> + mte_wait_after_trig(); >> + if ((fault == true) && > > Nitpick: just use "if (fault &&), it's a bool already. ok. > >> + (cur_mte_cxt.fault_valid == true || ret == EFAULT || read_len < len)) { >> + err = KSFT_PASS; >> + } else if ((fault == false) && >> + (cur_mte_cxt.fault_valid == false && read_len == len)) { > > Same here, !fault, !cur_mte_cxt.fault_valid. ok. > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel