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;
MIME-Version: 1.0
References: <20210201150028.2279522-1-jackmanb@google.com>
In-Reply-To: <20210201150028.2279522-1-jackmanb@google.com>
From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Mon, 1 Feb 2021 15:27:26 -0800
Message-ID: <CAADnVQKAaoiVM6=VGxKh=T1PWUNWLKFx+3zKf3Ehud6+LsJB3w@mail.gmail.com>
Subject: Re: [PATCH bpf-next v2] bpf: Propagate memory bounds to registers in
 atomics w/ BPF_FETCH
To:     Brendan Jackman <jackmanb@google.com>
Cc:     bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii.nakryiko@gmail.com>,
        KP Singh <kpsingh@chromium.org>,
        Florent Revest <revest@chromium.org>,
        John Fastabend <john.fastabend@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Feb 1, 2021 at 7:00 AM Brendan Jackman <jackmanb@google.com> wrote:
> +
> +SEC("fentry/bpf_fentry_test1")
> +int BPF_PROG(sub, int x)
> +{
> +       int a = 0;
> +       int b = __sync_fetch_and_add(&a, 1);

It probably needs ENABLE_ATOMICS_TESTS ?

Otherwise clang without -mcpu=v3 will complain:
"fatal error: error in backend: Invalid usage of the XADD return value"