From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932088AbcELOv0 (ORCPT ); Thu, 12 May 2016 10:51:26 -0400 Received: from foss.arm.com ([217.140.101.70]:59406 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751381AbcELOvY (ORCPT ); Thu, 12 May 2016 10:51:24 -0400 Message-ID: <573497FA.5030309@arm.com> Date: Thu, 12 May 2016 15:49:30 +0100 From: James Morse User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.6.0 MIME-Version: 1.0 To: David Long , Pratyush Anand CC: Catalin Marinas , Will Deacon , Sandeepa Prabhu , William Cohen , Steve Capper , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Marc Zyngier , Dave P Martin , Mark Rutland , Robin Murphy , Ard Biesheuvel , Jens Wiklander , Christoffer Dall , =?windows-1252?Q?Alex_?= =?windows-1252?Q?Benn=E9e?= , Yang Shi , Greg Kroah-Hartman , Viresh Kumar , "Suzuki K. Poulose" , Kees Cook , Zi Shen Lim , John Blackwood , Feng Kan , Balamurugan Shanmugam , Vladimir Murzin , Mark Salyzyn , Petr Mladek , Andrew Morton , Mark Brown Subject: Re: [PATCH v12 06/10] arm64: Treat all entry code as non-kprobe-able References: <1461783185-9056-1-git-send-email-dave.long@linaro.org> <1461783185-9056-7-git-send-email-dave.long@linaro.org> In-Reply-To: <1461783185-9056-7-git-send-email-dave.long@linaro.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi David, Pratyush On 27/04/16 19:53, David Long wrote: > From: Pratyush Anand > > Entry symbols are not kprobe safe. So blacklist them for kprobing. > > Signed-off-by: Pratyush Anand > diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c > index dfa1b1f..6a1292b 100644 > --- a/arch/arm64/kernel/kprobes.c > +++ b/arch/arm64/kernel/kprobes.c > @@ -29,6 +29,7 @@ > #include > #include > #include > +#include > > #include "kprobes-arm64.h" > > @@ -514,6 +515,15 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) > return 1; > } > > +bool arch_within_kprobe_blacklist(unsigned long addr) > +{ > + return (addr >= (unsigned long)__kprobes_text_start && > + addr < (unsigned long)__kprobes_text_end) || > + (addr >= (unsigned long)__entry_text_start && > + addr < (unsigned long)__entry_text_end) || > + !!search_exception_tables(addr); > +} > + Looking at __kvm_hyp_vector, we don't have support for handling breakpoints at EL2, so we should forbid kprobing these address ranges too: __hyp_text_start -> __hyp_text_end __hyp_idmap_text_start -> __hyp_idmap_text_end These can probably be guarded with is_kernel_in_hyp_mode(), if this is true then we are running with VHE where this code runs at the same exception level as the rest of the kernel, so we can probe them. (In this case you may want to add 'eret' to aarch64_insn_is_branch() in patch 2) Probing things in the kernel idmap sounds dangerous! Lets blacklist that too: __idmap_text_start -> __idmap_text_end Thanks, James