Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 29 Sep 2021 17:18:04 +0100
From:   Will Deacon <will@kernel.org>
To:     Lorenz Bauer <lmb@cloudflare.com>
Cc:     Daniel Borkmann <daniel@iogearbox.net>,
        Alexei Starovoitov <ast@kernel.org>,
        Zi Shen Lim <zlim.lnx@gmail.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        kernel-team@cloudflare.com, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next 2/4] bpf: define bpf_jit_alloc_exec_limit for
 arm64 JIT
Message-ID: <20210929161804.GF22029@willie-the-truck>
References: <20210924095542.33697-1-lmb@cloudflare.com>
 <20210924095542.33697-3-lmb@cloudflare.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210924095542.33697-3-lmb@cloudflare.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Precedence: bulk

On Fri, Sep 24, 2021 at 10:55:40AM +0100, Lorenz Bauer wrote:
> Expose the maximum amount of useable memory from the arm64 JIT.
> 
> Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
> ---
>  arch/arm64/net/bpf_jit_comp.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
> index 41c23f474ea6..803e7773fa86 100644
> --- a/arch/arm64/net/bpf_jit_comp.c
> +++ b/arch/arm64/net/bpf_jit_comp.c
> @@ -1136,6 +1136,11 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
>  	return prog;
>  }
>  
> +u64 bpf_jit_alloc_exec_limit(void)
> +{
> +	return BPF_JIT_REGION_SIZE;
> +}

Looks like this won't result in a functional change, as we happen to return
SZ_128M anyway thanks to the way in which the modules area is constructed.

But making this explicit is definitely better, so:

Acked-by: Will Deacon <will@kernel.org>

(I'm assuming this will go via the bpf tree, but please shout if I should
take it via arm64 instead)

Will