From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752422AbbABSGo (ORCPT ); Fri, 2 Jan 2015 13:06:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42423 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750768AbbABSGn (ORCPT ); Fri, 2 Jan 2015 13:06:43 -0500 Date: Fri, 2 Jan 2015 19:05:23 +0100 From: Oleg Nesterov To: Pratyush Anand Cc: linux-arm-kernel@lists.infradead.org, linux@arm.linux.org.uk, tixy@linaro.org, ananth@in.ibm.com, sandeepa.prabhu@linaro.org, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, anil.s.keshavamurthy@intel.com, masami.hiramatsu.pt@hitachi.com, wcohen@redhat.com Subject: Re: [RFC 6/8] ARM64: Handle TRAP_HWBRKPT for user mode as well Message-ID: <20150102180523.GC6761@redhat.com> References: <1e0a9e778669bb2a2e40bf101eff8ae85110ce54.1420038188.git.panand@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1e0a9e778669bb2a2e40bf101eff8ae85110ce54.1420038188.git.panand@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Let me repeat once again that I know absolutely nothing about arm* ;) On 12/31, Pratyush Anand wrote: > > uprobe registers a handler at step_hook. So, single_step_handler now > checks for user mode as well if there is a valid hook. > > Signed-off-by: Pratyush Anand > --- > arch/arm64/kernel/debug-monitors.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c > index b056369fd47d..2676b8655241 100644 > --- a/arch/arm64/kernel/debug-monitors.c > +++ b/arch/arm64/kernel/debug-monitors.c > @@ -236,6 +236,9 @@ static int single_step_handler(unsigned long addr, unsigned int esr, > if (!reinstall_suspended_bps(regs)) > return 0; > > + if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) > + return 0; > + > if (user_mode(regs)) { > info.si_signo = SIGTRAP; > info.si_errno = 0; > @@ -251,9 +254,6 @@ static int single_step_handler(unsigned long addr, unsigned int esr, > */ > user_rewind_single_step(current); > } else { > - if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) > - return 0; > - Agreed, we need something like this change... But did you verify that it can't break other users of register_step_hook() ? The current handlers do not check user_mode() == F, they assume that they can't be called otherwise. If this all is correct, please explain why in the changelog. The same for the next patch. Oleg.