From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Xu Kuohai <xukuohai@huawei.com>
Cc: bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
Will Deacon <will@kernel.org>, KP Singh <kpsingh@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Zi Shen Lim <zlim.lnx@gmail.com>, Martin KaFai Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
David Ahern <dsahern@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Russell King <rmk+kernel@armlinux.org.uk>,
James Morse <james.morse@arm.com>, Hou Tao <houtao1@huawei.com>,
Jason Wang <wangborong@cdjrlc.com>
Subject: Re: [PATCH bpf-next v7 4/4] bpf, arm64: bpf trampoline for arm64
Date: Mon, 11 Jul 2022 15:48:13 +0100 [thread overview]
Message-ID: <Ysw4LaMuNZQsoQXp@myrica> (raw)
In-Reply-To: <893b2d5f-16e9-0b1d-4ae6-8199e0f4ccf8@huawei.com>
On Mon, Jul 11, 2022 at 10:40:42PM +0800, Xu Kuohai wrote:
> On 7/11/2022 10:37 PM, Jean-Philippe Brucker wrote:
> > On Mon, Jul 11, 2022 at 10:16:00PM +0800, Xu Kuohai wrote:
> >>>> + if (save_ret)
> >>>> + emit(A64_STR64I(p->jited ? r0 : A64_R(0), A64_SP, retval_off),
> >>>> + ctx);
> >>>
> >>> This should be only A64_R(0), not r0. r0 happens to equal A64_R(0) when
> >>> jitted due to the way build_epilogue() builds the function at the moment,
> >>> but we shouldn't rely on that.
> >>>
> >>
> >> looks like I misunderstood something, will change it to:
> >>
> >> /* store return value, which is held in x0 for interpreter and in
> >> * bpf register r0 for JIT,
> >
> > It's simpler than that: in both cases the return value is in x0 because
> > the function follows the procedure call standard. You could drop the
> > comment to avoid confusion and only do the change to A64_R(0)
> >
>
> OK, will send v9 since v8 was just sent
Right sorry about this, I could have been clearer
Thanks,
Jean
prev parent reply other threads:[~2022-07-11 14:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-08 9:30 [PATCH bpf-next v7 0/4] bpf trampoline for arm64 Xu Kuohai
2022-07-08 9:30 ` [PATCH bpf-next v7 1/4] bpf: Remove is_valid_bpf_tramp_flags() Xu Kuohai
2022-07-08 9:30 ` [PATCH bpf-next v7 2/4] arm64: Add LDR (literal) instruction Xu Kuohai
2022-07-08 9:30 ` [PATCH bpf-next v7 3/4] bpf, arm64: Implement bpf_arch_text_poke() for arm64 Xu Kuohai
2022-07-08 9:30 ` [PATCH bpf-next v7 4/4] bpf, arm64: bpf trampoline " Xu Kuohai
2022-07-11 11:57 ` Jean-Philippe Brucker
2022-07-11 14:16 ` Xu Kuohai
2022-07-11 14:37 ` Jean-Philippe Brucker
2022-07-11 14:40 ` Xu Kuohai
2022-07-11 14:48 ` Jean-Philippe Brucker [this message]
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