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Date: Thu, 6 Jun 2019 11:44:12 -0300
From: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To: Leo Yan <leo.yan@...aro.org>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Namhyung Kim <namhyung@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
Adrian Hunter <adrian.hunter@...el.com>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Mike Leach <mike.leach@...aro.org>,
Suzuki K Poulose <suzuki.poulose@....com>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
bpf@...r.kernel.org
Subject: Re: [PATCH v2 3/4] perf augmented_raw_syscalls: Support arm64 raw
syscalls
Em Thu, Jun 06, 2019 at 10:12:31PM +0800, Leo Yan escreveu:
> Hi Arnaldo,
>
> On Thu, Jun 06, 2019 at 10:38:38AM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Jun 06, 2019 at 05:48:44PM +0800, Leo Yan escreveu:
> > > This patch adds support for arm64 raw syscall numbers so that we can use
> > > it on arm64 platform.
> > >
> > > After applied this patch, we need to specify macro -D__aarch64__ or
> > > -D__x86_64__ in compilation option so Clang can use the corresponding
> > > syscall numbers for arm64 or x86_64 respectively, other architectures
> > > will report failure when compilation.
> >
> > So, please check what I have in my perf/core branch, I've completely
> > removed arch specific stuff from augmented_raw_syscalls.c.
> >
> > What is done now is use a map to specify what to copy, that same map
> > that is used to state which syscalls should be traced.
> >
> > It uses that tools/perf/arch/arm64/entry/syscalls/mksyscalltbl to figure
> > out the mapping of syscall names to ids, just like is done for x86_64
> > and other arches, falling back to audit-libs when that syscalltbl thing
> > is not present.
>
> Actually I have noticed mksyscalltbl has been enabled for arm64, and
> had to say your approach is much better :)
>
> Thanks for the info and I will try your patch at my side.
That is excellent news! I'm eager to hear from you if this perf+BPF
integration experiment works for arm64.
I'm now trying to get past the verifier when checking if more than one
syscall arg is a filename, i.e. things like the rename* family, that
take two filenames.
An exercise in loop unrolling, providing the right hints to the
verifier, making sure clang don't trash those via explicit barriers, and
a lot of patience, limitless fun! ;-)
- Arnaldo
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