From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Florent Revest <revest@chromium.org>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>, Yonghong Song <yhs@fb.com>,
KP Singh <kpsingh@kernel.org>,
Brendan Jackman <jackmanb@chromium.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next v4 3/6] bpf: Add a bpf_snprintf helper
Date: Thu, 15 Apr 2021 16:11:35 -0700 [thread overview]
Message-ID: <CAEf4Bzbt0hmhJVYGwc4wp+jp209ed75oUQcTXg-NTX5ABzFBzw@mail.gmail.com> (raw)
In-Reply-To: <20210414185406.917890-4-revest@chromium.org>
On Wed, Apr 14, 2021 at 11:54 AM Florent Revest <revest@chromium.org> wrote:
>
> The implementation takes inspiration from the existing bpf_trace_printk
> helper but there are a few differences:
>
> To allow for a large number of format-specifiers, parameters are
> provided in an array, like in bpf_seq_printf.
>
> Because the output string takes two arguments and the array of
> parameters also takes two arguments, the format string needs to fit in
> one argument. Thankfully, ARG_PTR_TO_CONST_STR is guaranteed to point to
> a zero-terminated read-only map so we don't need a format string length
> arg.
>
> Because the format-string is known at verification time, we also do
> a first pass of format string validation in the verifier logic. This
> makes debugging easier.
>
> Signed-off-by: Florent Revest <revest@chromium.org>
> ---
LGTM.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
> include/linux/bpf.h | 1 +
> include/uapi/linux/bpf.h | 28 +++++++++++++++++++
> kernel/bpf/helpers.c | 50 ++++++++++++++++++++++++++++++++++
> kernel/bpf/verifier.c | 41 ++++++++++++++++++++++++++++
> kernel/trace/bpf_trace.c | 2 ++
> tools/include/uapi/linux/bpf.h | 28 +++++++++++++++++++
> 6 files changed, 150 insertions(+)
>
[...]
next prev parent reply other threads:[~2021-04-15 23:11 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-14 18:54 [PATCH bpf-next v4 0/6] Add a snprintf eBPF helper Florent Revest
2021-04-14 18:54 ` [PATCH bpf-next v4 1/6] bpf: Factorize bpf_trace_printk and bpf_seq_printf Florent Revest
2021-04-15 0:37 ` Andrii Nakryiko
2021-04-15 9:32 ` Florent Revest
2021-04-15 22:37 ` Andrii Nakryiko
2021-04-14 18:54 ` [PATCH bpf-next v4 2/6] bpf: Add a ARG_PTR_TO_CONST_STR argument type Florent Revest
2021-04-14 18:54 ` [PATCH bpf-next v4 3/6] bpf: Add a bpf_snprintf helper Florent Revest
2021-04-15 23:11 ` Andrii Nakryiko [this message]
2021-04-14 18:54 ` [PATCH bpf-next v4 4/6] libbpf: Initialize the bpf_seq_printf parameters array field by field Florent Revest
2021-04-14 18:54 ` [PATCH bpf-next v4 5/6] libbpf: Introduce a BPF_SNPRINTF helper macro Florent Revest
2021-04-14 18:54 ` [PATCH bpf-next v4 6/6] selftests/bpf: Add a series of tests for bpf_snprintf Florent Revest
2021-04-15 23:20 ` Andrii Nakryiko
2021-04-16 11:43 ` Florent Revest
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