From: Barret Rhoden <brho@google.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
mattbobrowski@google.com, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next 2/2] selftests/bpf: add inline assembly helpers to access array elements
Date: Thu, 4 Jan 2024 16:32:39 -0500 [thread overview]
Message-ID: <d6bd59f0-ba79-4e76-9fb7-aa07f86e4043@google.com> (raw)
In-Reply-To: <CAEf4BzauYF4DoQLV6AGfFcq3VgP2yi_Pd6pg2vj2Eb7Rt7j0Pg@mail.gmail.com>
On 1/3/24 16:21, Andrii Nakryiko wrote:
> On Wed, Jan 3, 2024 at 12:06 PM Barret Rhoden<brho@google.com> wrote:
>> On 1/3/24 14:51, Andrii Nakryiko wrote:
>>> I'm curious how bpf_cmp_likely/bpf_cmp_unlikely (just applied to
>>> bpf-next) compares to this?
>> these work great!
>>
>> e.g.
>>
>> if (bpf_cmp_likely(idx, <, NR_MAP_ELEMS))
>> map_elems[idx] = i;
>>
>> works fine. since that's essentially the code that bpf_array_elem() was
>> trying to replace, i'd rather just use the new bpf_cmp helpers than have
>> the special array_elem helpers.
> ok, cool, thanks for checking! The less special macros, the better.
sorry - turns out it only worked in testing. in my actual program, i
still run into issues. the comparison is done, which is what bpf_cmp
enforces. but the compiler is discarding the comparison. i have more
info in the other thread, but figured i'd mention it here too. =(
next prev parent reply other threads:[~2024-01-04 21:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-03 15:33 [PATCH bpf-next 0/2] inline asm helpers to access array elements Barret Rhoden
2024-01-03 15:33 ` [PATCH bpf-next 1/2] libbpf: add helpers for mmapping maps Barret Rhoden
2024-01-03 16:57 ` John Fastabend
2024-01-03 18:50 ` Barret Rhoden
2024-01-03 15:33 ` [PATCH bpf-next 2/2] selftests/bpf: add inline assembly helpers to access array elements Barret Rhoden
2024-01-03 17:52 ` John Fastabend
2024-01-03 19:51 ` Andrii Nakryiko
2024-01-03 20:06 ` Barret Rhoden
2024-01-03 21:21 ` Andrii Nakryiko
2024-01-04 21:32 ` Barret Rhoden [this message]
2024-01-04 21:37 ` Barret Rhoden
2024-01-04 22:45 ` Andrii Nakryiko
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