From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 009913BB5B for ; Thu, 30 Nov 2023 13:15:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BfDBPr8f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E9CCC433C8; Thu, 30 Nov 2023 13:15:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701350145; bh=ESm2XXf+f9FWS1yFlh8OmKYXTJZxIwuCreSBi7nmY00=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BfDBPr8fn0WoNKCpDTDlL374d6/n0Vh5pSkf88RafdnaRhwVotRG1gVzSgfUfMnUr FnnGbWOHMSre9aDBVg64y3N8n50e+vkNiLNsLk/fSC6KIOVV0cixMVjQeVRu48jNTZ VLfEY1Yafvf4nAOMyFKxPv7ydsO00A173dW3KphDPMie9GHH9/S9gBbaGrzJaSAvNS wn+ISUZ23eruuJlQRrJXWjrk3uPQGmjC0iw/t3VoiVZ4XSwwI8IdU3Ar1IX/XL/OTv rakfqB4dPjcYqcTFCMyhw10buFsGUMKGYcoprxGQ0d+8cndqwbSsPnFWyeCRLWv0l2 SW9Mu6EeOPdDg== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 1BF0840094; Thu, 30 Nov 2023 10:15:43 -0300 (-03) Date: Thu, 30 Nov 2023 10:15:43 -0300 From: Arnaldo Carvalho de Melo To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Adrian Hunter , Nick Terrell , Kan Liang , Andi Kleen , Kajol Jain , Athira Rajeev , Huacai Chen , Masami Hiramatsu , Vincent Whitchurch , "Steinar H. Gunderson" , Liam Howlett , Miguel Ojeda , Colin Ian King , Dmitrii Dolgov <9erthalion6@gmail.com>, Yang Jihong , Ming Wang , James Clark , K Prateek Nayak , Sean Christopherson , Leo Yan , Ravi Bangoria , German Gomez , Changbin Du , Paolo Bonzini , Li Dong , Sandipan Das , liuwenyu , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Guilherme Amadio Subject: Re: [PATCH v5 02/50] libperf: Lazily allocate/size mmap event copy Message-ID: References: <20231127220902.1315692-1-irogers@google.com> <20231127220902.1315692-3-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20231127220902.1315692-3-irogers@google.com> X-Url: http://acmel.wordpress.com Em Mon, Nov 27, 2023 at 02:08:14PM -0800, Ian Rogers escreveu: > The event copy in the mmap is used to have storage to read an > event. Not all users of mmaps read the events, such as perf > record. The amount of buffer was also statically set to > PERF_SAMPLE_MAX_SIZE rather than the amount necessary from the > header's event size. Switch to a model where the event_copy is > reallocated if too small to the event's size. This adds the potential > for the event to move, so if a copy of the event pointer were stored > it could be broken. All the current users do: > > while(event = perf_mmap__read_event()) { ... } > > and so they would be broken due to the event being overwritten if they > had stored the pointer. Manual inspection and address sanitizer > testing also shows the event pointer not being stored. > > Signed-off-by: Ian Rogers > --- > tools/lib/perf/include/internal/mmap.h | 3 ++- > tools/lib/perf/mmap.c | 21 ++++++++++++++++++--- > 2 files changed, 20 insertions(+), 4 deletions(-) > > diff --git a/tools/lib/perf/include/internal/mmap.h b/tools/lib/perf/include/internal/mmap.h > index 5a062af8e9d8..5f08cab61ece 100644 > --- a/tools/lib/perf/include/internal/mmap.h > +++ b/tools/lib/perf/include/internal/mmap.h > @@ -33,7 +33,8 @@ struct perf_mmap { > bool overwrite; > u64 flush; > libperf_unmap_cb_t unmap_cb; > - char event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8); > + void *event_copy; > + size_t event_copy_sz; > struct perf_mmap *next; > }; > > diff --git a/tools/lib/perf/mmap.c b/tools/lib/perf/mmap.c > index 2184814b37dd..c829db7bf1fa 100644 > --- a/tools/lib/perf/mmap.c > +++ b/tools/lib/perf/mmap.c > @@ -19,6 +19,7 @@ > void perf_mmap__init(struct perf_mmap *map, struct perf_mmap *prev, > bool overwrite, libperf_unmap_cb_t unmap_cb) > { > + /* Assume fields were zero initialized. */ > map->fd = -1; > map->overwrite = overwrite; > map->unmap_cb = unmap_cb; > @@ -51,13 +52,19 @@ int perf_mmap__mmap(struct perf_mmap *map, struct perf_mmap_param *mp, > > void perf_mmap__munmap(struct perf_mmap *map) > { > - if (map && map->base != NULL) { > + if (!map) > + return; > + > + free(map->event_copy); > + map->event_copy = NULL; I´m converting this to: zfree(&map->event_copy); Hopefully we'll find some tool to flag these before submitting patches, does clang-tidy do these kinds of things? Also, applied: b4 am -P2,4-7 -ctsl --cc-trailers 20231127220902.1315692-1-irogers@google.com The ones that Namhyung acked and that applied cleanly in order. The first one, as Namhyung noted, is already merged. - Arnaldo