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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16B00C352A1 for ; Wed, 30 Nov 2022 10:52:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232888AbiK3KwE (ORCPT ); Wed, 30 Nov 2022 05:52:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233016AbiK3KwD (ORCPT ); Wed, 30 Nov 2022 05:52:03 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D0B673400; Wed, 30 Nov 2022 02:52:02 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id 02D7161AFE; Wed, 30 Nov 2022 10:52:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 869EAC433C1; Wed, 30 Nov 2022 10:51:59 +0000 (UTC) Date: Wed, 30 Nov 2022 10:51:56 +0000 From: Catalin Marinas To: Tomislav Novak Cc: Alexei Starovoitov , Will Deacon , "bpf@vger.kernel.org" , "linux-perf-users@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Samuel Gosselin , Mark Rutland , Russell King Subject: Re: [PATCH] hw_breakpoint: fix single-stepping when using bpf_overflow_handler Message-ID: References: <20220923203644.2731604-1-tnovak@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On Mon, Nov 28, 2022 at 11:59:37AM +0000, Tomislav Novak wrote: > On Tue, Nov 15, 2022 at 03:09:37PM +0000, Catalin Marinas wrote: > > > On ARM platforms is_default_overflow_handler() is used to determine if > > > hw_breakpoint code should single-step over the watchpoint trigger or > > > let the custom handler deal with it. > > > > > > Attaching a BPF program to a watchpoint replaces the handler with > > > bpf_overflow_handler, which isn't recognized as a default handler so we > > > never step over the instruction triggering the data abort exception (the > > > watchpoint keeps firing): > > > > > > # bpftrace -e 'watchpoint:0x10000000:4:w { printf("hit\n"); }' ./wp_test > > > Attaching 1 probe... > > > hit > > > hit > > > hit > > > [...] > > > > > > (wp_test performs a single 4-byte store to address 0x10000000) > > > > > > This patch replaces the check with uses_default_overflow_handler(), which > > > accounts for the bpf_overflow_handler() case by also testing if the handler > > > invokes one of the perf_event_output functions via orig_default_handler. > > > > > > Signed-off-by: Tomislav Novak > > > Tested-by: Samuel Gosselin # arm64 > > > --- > > > arch/arm/kernel/hw_breakpoint.c | 8 ++++---- > > > arch/arm64/kernel/hw_breakpoint.c | 4 ++-- > > > include/linux/perf_event.h | 22 +++++++++++++++++++--- > > > 3 files changed, 25 insertions(+), 9 deletions(-) > > > > It looks like this slipped through the cracks. I'm fine with the patch > > but could you split the arm and arm64 parts in separate patches? Unless > > rmk acks it and we can take the patch through the arm64 (or perf) tree. > > Thanks for reviewing! > > Given the changes in the arch-independent perf_event.h, I think merging it > as a single commit may be easiest (assuming rmk acks it). > > Alternatively I could move arm changes into a separate patch, keeping arm64 > and perf_event.h in this one (possibly splitting out the latter into its own > commit). One that's merged, the arm patch could be submitted to linux-arm. > What would you prefer? Actually, arch/arm*/kernel/hw_breakpoint.c come under the ARM PMU profiling, so no need to split the patch. It may need an ack from the generic perf maintainers for include/linux/perf.h. FWIW, Reviewed-by: Catalin Marinas