From: Song Liu <songliubraving@fb.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
"davem@davemloft.net" <davem@davemloft.net>,
"daniel@iogearbox.net" <daniel@iogearbox.net>,
"x86@kernel.org" <x86@kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH v2 bpf-next 03/17] bpf: Introduce BPF trampoline
Date: Thu, 7 Nov 2019 23:16:20 +0000 [thread overview]
Message-ID: <22015BB9-7A84-4F5E-A8A5-D10CB9DA3AEE@fb.com> (raw)
In-Reply-To: <20191107230923.knpejhp6fbyzioxi@ast-mbp.dhcp.thefacebook.com>
> On Nov 7, 2019, at 3:09 PM, Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
>
> On Thu, Nov 07, 2019 at 11:07:21PM +0000, Song Liu wrote:
>>
>>
>>>
>>>
>>>>> +
>>>>> +static int bpf_trampoline_update(struct bpf_prog *prog)
>>>>
>>>> Seems argument "prog" is not used at all?
>>>
>>> like one below ? ;)
>> e... I was really dumb... sorry..
>>
>> Maybe we should just pass the tr in?
>
> that would be imbalanced.
Hmm.. what do you mean by imbalanced?
>
>>>
>>>>> +{
>>>>> + struct bpf_trampoline *tr = prog->aux->trampoline;
>>>>> + void *old_image = tr->image + ((tr->selector + 1) & 1) * PAGE_SIZE/2;
>>>>> + void *new_image = tr->image + (tr->selector & 1) * PAGE_SIZE/2;
>>>>> + if (err)
>>>>> + goto out;
>>>>> + tr->selector++;
>>>>
>>>> Shall we do selector-- for unlink?
>>>
>>> It's a bit flip. I think it would be more confusing with --
>>
>> Right.. Maybe should use int instead of u64 for selector?
>
> No, since int can overflow.
I guess it is OK to overflow, no?
next prev parent reply other threads:[~2019-11-07 23:16 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-07 5:46 [PATCH v2 bpf-next 00/17] Introduce BPF trampoline Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 01/17] bpf: refactor x86 JIT into helpers Alexei Starovoitov
2019-11-07 17:05 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 02/17] bpf: Add bpf_arch_text_poke() helper Alexei Starovoitov
2019-11-07 17:20 ` Song Liu
2019-11-07 17:50 ` Alexei Starovoitov
2019-11-07 17:54 ` Alexei Starovoitov
2019-11-07 18:04 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 03/17] bpf: Introduce BPF trampoline Alexei Starovoitov
2019-11-07 22:37 ` Song Liu
2019-11-07 22:55 ` Alexei Starovoitov
2019-11-07 23:07 ` Song Liu
2019-11-07 23:09 ` Alexei Starovoitov
2019-11-07 23:16 ` Song Liu [this message]
2019-11-08 0:09 ` Alexei Starovoitov
2019-11-08 1:10 ` Song Liu
2019-11-08 3:11 ` Alexei Starovoitov
2019-11-08 4:06 ` Song Liu
2019-11-08 4:08 ` Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 04/17] libbpf: Add support to attach to fentry/fexit tracing progs Alexei Starovoitov
2019-11-07 22:51 ` Song Liu
2019-11-07 23:07 ` Alexei Starovoitov
2019-11-07 23:13 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 05/17] selftest/bpf: Simple test for fentry/fexit Alexei Starovoitov
2019-11-07 23:22 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 06/17] bpf: Add kernel test functions for fentry testing Alexei Starovoitov
2019-11-07 23:28 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 07/17] selftests/bpf: Add test for BPF trampoline Alexei Starovoitov
2019-11-08 1:17 ` Song Liu
2019-11-08 2:33 ` Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 08/17] selftests/bpf: Add fexit tests " Alexei Starovoitov
2019-11-08 1:22 ` Song Liu
2019-11-07 5:46 ` [PATCH v2 bpf-next 09/17] selftests/bpf: Add combined fentry/fexit test Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 10/17] selftests/bpf: Add stress test for maximum number of progs Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 11/17] bpf: Reserver space for BPF trampoline in BPF programs Alexei Starovoitov
2019-11-08 5:03 ` Andrii Nakryiko
2019-11-07 5:46 ` [PATCH v2 bpf-next 12/17] bpf: Fix race in btf_resolve_helper_id() Alexei Starovoitov
2019-11-08 5:13 ` Andrii Nakryiko
2019-11-08 5:31 ` Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 13/17] bpf: Compare BTF types of functions arguments with actual types Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 14/17] bpf: Support attaching tracing BPF program to other BPF programs Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 15/17] selftests/bpf: Extend test_pkt_access test Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 16/17] libbpf: Add support for attaching BPF programs to other BPF programs Alexei Starovoitov
2019-11-07 14:33 ` Alexei Starovoitov
2019-11-07 5:46 ` [PATCH v2 bpf-next 17/17] selftests/bpf: Add a test for attaching BPF prog to another BPF prog and subprog Alexei Starovoitov
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