Re: [PATCH bpf-next v3 1/2] arm64: stacktrace: Implement arch_bpf_stack_walk() for the BPF JIT

From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Puranjay Mohan <puranjay12@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	 Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	 Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>,
	 Yonghong Song <yonghong.song@linux.dev>,
	John Fastabend <john.fastabend@gmail.com>,
	 KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
	 Jiri Olsa <jolsa@kernel.org>, Zi Shen Lim <zlim.lnx@gmail.com>,
	Will Deacon <will@kernel.org>,  bpf <bpf@vger.kernel.org>,
	 linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	 Kumar Kartikeya Dwivedi <memxor@gmail.com>
Subject: Re: [PATCH bpf-next v3 1/2] arm64: stacktrace: Implement arch_bpf_stack_walk() for the BPF JIT
Date: Tue, 27 Feb 2024 13:57:55 -0800	[thread overview]
Message-ID: <CAADnVQKYZdAmh3V_259adfcMsRRGBrXR4k=yJ2heVMQ+AuQ8Xg@mail.gmail.com> (raw)
In-Reply-To: <Zd4lggegV2MeD3jP@arm.com>

On Tue, Feb 27, 2024 at 10:10 AM Catalin Marinas
<catalin.marinas@arm.com> wrote:
>
> On Tue, Feb 27, 2024 at 06:01:56PM +0000, Catalin Marinas wrote:
> > On Thu, Feb 22, 2024 at 06:04:35PM -0800, Alexei Starovoitov wrote:
> > > On Thu, Feb 22, 2024 at 11:28 AM Catalin Marinas
> > > <catalin.marinas@arm.com> wrote:
> > > > On Thu, Feb 01, 2024 at 12:52:24PM +0000, Puranjay Mohan wrote:
> > > > > This will be used by bpf_throw() to unwind till the program marked as
> > > > > exception boundary and run the callback with the stack of the main
> > > > > program.
> > > > >
> > > > > This is required for supporting BPF exceptions on ARM64.
> > > > >
> > > > > Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
> > > > > ---
> > > > >  arch/arm64/kernel/stacktrace.c | 26 ++++++++++++++++++++++++++
> > > > >  1 file changed, 26 insertions(+)
> > [...]
> > > > I guess you want this to be merged via the bpf tree?
> > >
> > > We typically take bpf jit patches through bpf-next, since
> > > we do cross arch jits refactoring from time to time,
> > > but nothing like this is pending for this merge window,
> > > so if you want it to go through arm64 tree that's fine with us.
> >
> > I don't have any preference. I can add it on top of the other arm64
> > patches if there are no dependencies on it from your side.
>
> Actually, it depends on patches in bpf-next AFAICT (it doesn't apply
> cleanly on top of vanilla -rc3). So please take the patches through the
> bpf tree.

Ok. Took it into bpf-next.

Please take a look at these Puranjay's patchset:

https://patchwork.kernel.org/project/netdevbpf/cover/20240221145106.105995-1-puranjay12@gmail.com/

It's a pretty nice performance improvement.