From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>,
LKML <linux-kernel@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Vlastimil Babka <vbabka@suse.cz>,
Roman Gushchin <roman.gushchin@linux.dev>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
linux-mm <linux-mm@kvack.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Kees Cook <kees@kernel.org>,
"Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH v5 bpf-next 2/3] mm/bpf: Add bpf_get_kmem_cache() kfunc
Date: Fri, 11 Oct 2024 11:35:27 -0700 [thread overview]
Message-ID: <CAADnVQLN1De95WqUu2ESAdX-wNvaGhSNeboar1k-O+z_d7-dNA@mail.gmail.com> (raw)
In-Reply-To: <20241010232505.1339892-3-namhyung@kernel.org>
On Thu, Oct 10, 2024 at 4:25 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> The bpf_get_kmem_cache() is to get a slab cache information from a
> virtual address like virt_to_cache(). If the address is a pointer
> to a slab object, it'd return a valid kmem_cache pointer, otherwise
> NULL is returned.
>
> It doesn't grab a reference count of the kmem_cache so the caller is
> responsible to manage the access. The returned point is marked as
> PTR_UNTRUSTED. And the kfunc has KF_RCU_PROTECTED as the slab object
> might be protected by RCU.
...
> +BTF_ID_FLAGS(func, bpf_get_kmem_cache, KF_RCU_PROTECTED)
This flag is unnecessary. PTR_UNTRUSTED can point to absolutely any memory.
In this case it likely points to a valid kmem_cache, but
the verifier will guard all accesses with probe_read anyway.
I can remove this flag while applying.
next prev parent reply other threads:[~2024-10-11 18:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-10 23:25 [PATCH v5 bpf-next 0/3] bpf: Add kmem_cache iterator and kfunc Namhyung Kim
2024-10-10 23:25 ` [PATCH v5 bpf-next 1/3] bpf: Add kmem_cache iterator Namhyung Kim
2024-10-11 18:33 ` Alexei Starovoitov
2024-10-11 19:13 ` Namhyung Kim
2024-10-11 18:44 ` Alexei Starovoitov
2024-10-11 19:41 ` Andrii Nakryiko
2024-10-11 19:43 ` Andrii Nakryiko
2024-10-14 15:25 ` Vlastimil Babka
2024-10-10 23:25 ` [PATCH v5 bpf-next 2/3] mm/bpf: Add bpf_get_kmem_cache() kfunc Namhyung Kim
2024-10-11 18:35 ` Alexei Starovoitov [this message]
2024-10-11 19:14 ` Namhyung Kim
2024-10-14 18:13 ` Namhyung Kim
2024-10-15 1:50 ` Alexei Starovoitov
2024-10-15 18:19 ` Namhyung Kim
2024-10-15 18:25 ` Alexei Starovoitov
2024-10-15 20:54 ` Namhyung Kim
2024-10-10 23:25 ` [PATCH v5 bpf-next 3/3] selftests/bpf: Add a test for kmem_cache_iter Namhyung Kim
2024-10-15 2:00 ` [PATCH v5 bpf-next 0/3] bpf: Add kmem_cache iterator and kfunc patchwork-bot+netdevbpf
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAADnVQLN1De95WqUu2ESAdX-wNvaGhSNeboar1k-O+z_d7-dNA@mail.gmail.com \
--to=alexei.starovoitov@gmail.com \
--cc=42.hyeyoo@gmail.com \
--cc=acme@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=cl@linux.com \
--cc=daniel@iogearbox.net \
--cc=eddyz87@gmail.com \
--cc=haoluo@google.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=john.fastabend@gmail.com \
--cc=jolsa@kernel.org \
--cc=kees@kernel.org \
--cc=kpsingh@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=martin.lau@linux.dev \
--cc=namhyung@kernel.org \
--cc=paulmck@kernel.org \
--cc=penberg@kernel.org \
--cc=rientjes@google.com \
--cc=roman.gushchin@linux.dev \
--cc=sdf@fomichev.me \
--cc=song@kernel.org \
--cc=vbabka@suse.cz \
--cc=yonghong.song@linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox