Re: [dpdk-dev] [PATCH 7/8] bpf/arm64: add atomic-exchange-and-add operation

From: David Marchand <david.marchand@redhat.com>
To: Jerin Jacob Kollanukkaran <jerinj@marvell.com>,
	Thomas Monjalon <thomas@monjalon.net>
Cc: dev <dev@dpdk.org>,
	"Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
	 Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>,
	Gavin Hu <gavin.hu@arm.com>
Subject: Re: [dpdk-dev] [PATCH 7/8] bpf/arm64: add atomic-exchange-and-add operation
Date: Fri, 18 Oct 2019 15:16:51 +0200	[thread overview]
Message-ID: <CAJFAV8yyRrRnOfNS64jtdSaQqDoiXs0uRt4A-hEC+3v5--jGKQ@mail.gmail.com> (raw)
In-Reply-To: <20190903105938.33231-8-jerinj@marvell.com>

On Tue, Sep 3, 2019 at 1:00 PM <jerinj@marvell.com> wrote:
>
> From: Jerin Jacob <jerinj@marvell.com>
>
> Implement XADD eBPF instruction using STADD arm64 instruction.
> If the given platform does not have atomics support,
> use LDXR and STXR pair for critical section instead of STADD.

For the record, this patch had a missed dependency on the 128-bits
atomic for arm64 patch because of RTE_ARM_FEATURE_ATOMICS.
This will be resolved once the latter is merged.

> ---
>  lib/librte_bpf/bpf_jit_arm64.c | 85 +++++++++++++++++++++++++++++++++-
>  1 file changed, 84 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_bpf/bpf_jit_arm64.c b/lib/librte_bpf/bpf_jit_arm64.c
> index c797c9c62..62fa6a505 100644
> --- a/lib/librte_bpf/bpf_jit_arm64.c
> +++ b/lib/librte_bpf/bpf_jit_arm64.c

[snip]

> +static int
> +has_atomics(void)
> +{
> +       int rc = 0;
> +
> +#if defined(__ARM_FEATURE_ATOMICS) || defined(RTE_ARM_FEATURE_ATOMICS)
> +       rc = 1;
> +#endif
> +       return rc;
> +}

[snip]

-- 
David Marchand