From: Hari Bathini <hbathini@linux.ibm.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc: Song Liu <songliubraving@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
John Fastabend <john.fastabend@gmail.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Paul Mackerras <paulus@samba.org>,
Jordan Niethe <jniethe5@gmail.com>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
Yonghong Song <yhs@fb.com>, KP Singh <kpsingh@kernel.org>,
Martin KaFai Lau <kafai@fb.com>
Subject: Re: [PATCH v2 4/5] bpf ppc32: add support for BPF_ATOMIC bitwise operations
Date: Tue, 14 Jun 2022 00:30:36 +0530 [thread overview]
Message-ID: <6a991140-f0f8-dbfc-d596-ce1473251034@linux.ibm.com> (raw)
In-Reply-To: <0f41cc76-a214-03c5-8764-808e5001b906@csgroup.eu>
On 11/06/22 10:44 pm, Christophe Leroy wrote:
>
>
> Le 10/06/2022 à 17:55, Hari Bathini a écrit :
>> Adding instructions for ppc32 for
>>
>> atomic_and
>> atomic_or
>> atomic_xor
>> atomic_fetch_add
>> atomic_fetch_and
>> atomic_fetch_or
>> atomic_fetch_xor
>>
>> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
>> ---
>>
>> Changes in v2:
>> * Used an additional register (BPF_REG_AX)
>> - to avoid clobbering src_reg.
>> - to keep the lwarx reservation as intended.
>> - to avoid the odd switch/goto construct.
>
> Might be a stupid question as I don't know the internals of BPF: Are we
> sure BPF_REG_AX cannot be the src reg or the dst reg ?
>
AFAICS, BPF_REG_AX wouldn't be used as src_reg or dst_reg unless this
code is reused internally, by arch-specific code, for JIT'ing some other
instruction(s) using BPF_REG_AX as either src or dst reg..
Thanks
Hari
next prev parent reply other threads:[~2022-06-13 19:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-10 15:55 [PATCH v2 0/5] Atomics support for eBPF on powerpc Hari Bathini
2022-06-10 15:55 ` [PATCH v2 1/5] bpf ppc64: add support for BPF_ATOMIC bitwise operations Hari Bathini
2022-06-10 15:55 ` [PATCH v2 2/5] bpf ppc64: add support for atomic fetch operations Hari Bathini
2022-06-10 15:55 ` [PATCH v2 3/5] bpf ppc64: Add instructions for atomic_[cmp]xchg Hari Bathini
2022-06-10 15:55 ` [PATCH v2 4/5] bpf ppc32: add support for BPF_ATOMIC bitwise operations Hari Bathini
2022-06-11 17:14 ` Christophe Leroy
2022-06-13 19:00 ` Hari Bathini [this message]
2022-06-10 15:55 ` [PATCH v2 5/5] bpf ppc32: Add instructions for atomic_[cmp]xchg Hari Bathini
2022-06-11 17:34 ` Christophe Leroy
2022-06-13 19:11 ` Hari Bathini
2022-06-13 19:14 ` Hari Bathini
2022-06-24 10:41 ` Naveen N. Rao
2022-06-24 10:37 ` [PATCH v2 0/5] Atomics support for eBPF on powerpc Naveen N. Rao
2022-07-04 11:33 ` Michael Ellerman
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