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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 B1F0AC8300A for ; Thu, 30 Apr 2020 11:36:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 913492076D for ; Thu, 30 Apr 2020 11:36:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727029AbgD3LgW (ORCPT ); Thu, 30 Apr 2020 07:36:22 -0400 Received: from foss.arm.com ([217.140.110.172]:52952 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726626AbgD3LgV (ORCPT ); Thu, 30 Apr 2020 07:36:21 -0400 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 E175731B; Thu, 30 Apr 2020 04:36:20 -0700 (PDT) Received: from [10.57.27.210] (unknown [10.57.27.210]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D2D153F305; Thu, 30 Apr 2020 04:36:17 -0700 (PDT) Subject: Re: [PATCH v2 1/2] arm64/crash_core: Export KERNELPACMASK in vmcoreinfo To: linux-arm-kernel@lists.infradead.org Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , Bhupesh Sharma , Vincenzo Frascino , James Morse , Mark Rutland References: <1587968702-19996-1-git-send-email-amit.kachhap@arm.com> From: Amit Kachhap Message-ID: <36929ba3-3274-6046-9a47-ed403f00fefe@arm.com> Date: Thu, 30 Apr 2020 17:05:55 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <1587968702-19996-1-git-send-email-amit.kachhap@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Will/Catalin, On 4/27/20 11:55 AM, Amit Daniel Kachhap wrote: > Recently arm64 linux kernel added support for Armv8.3-A Pointer > Authentication feature. If this feature is enabled in the kernel and the > hardware supports address authentication then the return addresses are > signed and stored in the stack to prevent ROP kind of attack. Kdump tool > will now dump the kernel with signed lr values in the stack. > > Any user analysis tool for this kernel dump may need the kernel pac mask > information in vmcoreinfo to generate the correct return address for > stacktrace purpose as well as to resolve the symbol name. > > This patch is similar to commit ec6e822d1a22d0eef ("arm64: expose user PAC > bit positions via ptrace") which exposes pac mask information via ptrace > interfaces. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Mark Rutland > Signed-off-by: Amit Daniel Kachhap This patch user side changes are accepted by crash-utility maintainer [1] so I think this is in a good shape to go in. Thanks, Amit Daniel [1]: https://www.redhat.com/archives/crash-utility/2020-April/msg00099.html > --- > Changes since v1: > * Rebased to kernel 5.7-rc3. > * commit log change. > > An implementation of this new KERNELPACMASK vmcoreinfo field used by crash > tool can be found here[1]. This change is accepted by crash utility > maintainer [2]. > > [1]: https://www.redhat.com/archives/crash-utility/2020-April/msg00095.html > [2]: https://www.redhat.com/archives/crash-utility/2020-April/msg00099.html > > arch/arm64/include/asm/compiler.h | 3 +++ > arch/arm64/kernel/crash_core.c | 4 ++++ > 2 files changed, 7 insertions(+) > > diff --git a/arch/arm64/include/asm/compiler.h b/arch/arm64/include/asm/compiler.h > index eece20d..32d5900 100644 > --- a/arch/arm64/include/asm/compiler.h > +++ b/arch/arm64/include/asm/compiler.h > @@ -19,6 +19,9 @@ > #define __builtin_return_address(val) \ > (void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val))) > > +#else /* !CONFIG_ARM64_PTR_AUTH */ > +#define ptrauth_user_pac_mask() 0ULL > +#define ptrauth_kernel_pac_mask() 0ULL > #endif /* CONFIG_ARM64_PTR_AUTH */ > > #endif /* __ASM_COMPILER_H */ > diff --git a/arch/arm64/kernel/crash_core.c b/arch/arm64/kernel/crash_core.c > index ca4c3e1..25cf2ce 100644 > --- a/arch/arm64/kernel/crash_core.c > +++ b/arch/arm64/kernel/crash_core.c > @@ -6,6 +6,7 @@ > > #include > #include > +#include > > void arch_crash_save_vmcoreinfo(void) > { > @@ -16,4 +17,7 @@ void arch_crash_save_vmcoreinfo(void) > vmcoreinfo_append_str("NUMBER(PHYS_OFFSET)=0x%llx\n", > PHYS_OFFSET); > vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset()); > + vmcoreinfo_append_str("NUMBER(KERNELPACMASK)=0x%llx\n", > + system_supports_address_auth() ? > + ptrauth_kernel_pac_mask() : 0); > } >