From nobody Thu Nov 28 10:54:53 2024 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C34A21D1F72; Wed, 2 Oct 2024 18:09:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727892599; cv=none; b=CL0Gf+sYRRpX6z5i0zGlYegvyKLOsEw4AP+lHLGucfK4PxAM642YUZWYdfO7kalbhZBiQNw2SwlBZdUeEcK+wg1mEMjPShN9V4KZj+trAJF1t6VzMgPRWXtqTx7R22ol8X5nlQZVBp6uhQF6ECGLXiwLJbUaQvsQ/xQfN4aZslM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727892599; c=relaxed/simple; bh=CZ1VN+wISqfF7U/NBBkytViSmRb/vkGLNUY76gXrLxU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=L2j1PUU6FHA0glexkQZAh8s4EGSwR1WL0618lZQrM21y8YBVR9y6GoykxJCUTO2sYtHPb4S/5veImM/Fvw7f0fFwNmaHWtNtB9yGBcnUxiXRaVbtPi4aucsDfxyusCHcSF90RMwC7jZSaYSaqEgxmeMWUFBpbsapEweGj3hZD/A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=C1nN9bS1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="C1nN9bS1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3F17C4CED6; Wed, 2 Oct 2024 18:09:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727892599; bh=CZ1VN+wISqfF7U/NBBkytViSmRb/vkGLNUY76gXrLxU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C1nN9bS1juVNiiTLMsoIIP2DGHBhXblmGXHhsKBD+j6XPJwI5tpUtFSZYdSkMTJVU PBXFgrsz8B8ZV+VT0cgqgK6qrFs2w4+ycrTH0yA9gyW/m5l7V02/XBNfHa+8kFJAxc 4lDiS2LMUucmUhiFgs7PefmznRoDDt92VSgPcL4FERTeuDorLGV9p9f336azJI+4UE OA/Xcg20450+n41GGYuAvcr+sjyEwfRG4b5943hnrFLr1Jc36oc3uHQDVlH90Kgvc4 otDwmKd42es+dgexigXc+VKAxyPI3gA5HxIY2GFemE/uxwLmPRtnBaR2WSVkvv29E2 eedyeP/3Sdorw== From: Namhyung Kim To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , LKML , bpf@vger.kernel.org, Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, Arnaldo Carvalho de Melo , Kees Cook Subject: [PATCH v4 bpf-next 2/3] mm/bpf: Add bpf_get_kmem_cache() kfunc Date: Wed, 2 Oct 2024 11:09:55 -0700 Message-ID: <20241002180956.1781008-3-namhyung@kernel.org> X-Mailer: git-send-email 2.46.1.824.gd892dcdcdd-goog In-Reply-To: <20241002180956.1781008-1-namhyung@kernel.org> References: <20241002180956.1781008-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 intended use case for now is to symbolize locks in slab objects from the lock contention tracepoints. Suggested-by: Vlastimil Babka Acked-by: Roman Gushchin (mm/*) Acked-by: Vlastimil Babka #mm/slab Signed-off-by: Namhyung Kim --- kernel/bpf/helpers.c | 1 + mm/slab_common.c | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 4053f279ed4cc7ab..3709fb14288105c6 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -3090,6 +3090,7 @@ BTF_ID_FLAGS(func, bpf_iter_bits_new, KF_ITER_NEW) BTF_ID_FLAGS(func, bpf_iter_bits_next, KF_ITER_NEXT | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_iter_bits_destroy, KF_ITER_DESTROY) BTF_ID_FLAGS(func, bpf_copy_from_user_str, KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_get_kmem_cache, KF_RET_NULL) BTF_KFUNCS_END(common_btf_ids) =20 static const struct btf_kfunc_id_set common_kfunc_set =3D { diff --git a/mm/slab_common.c b/mm/slab_common.c index 7443244656150325..5484e1cd812f698e 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1322,6 +1322,25 @@ size_t ksize(const void *objp) } EXPORT_SYMBOL(ksize); =20 +#ifdef CONFIG_BPF_SYSCALL +#include + +__bpf_kfunc_start_defs(); + +__bpf_kfunc struct kmem_cache *bpf_get_kmem_cache(u64 addr) +{ + struct slab *slab; + + if (!virt_addr_valid(addr)) + return NULL; + + slab =3D virt_to_slab((void *)(long)addr); + return slab ? slab->slab_cache : NULL; +} + +__bpf_kfunc_end_defs(); +#endif /* CONFIG_BPF_SYSCALL */ + /* Tracepoints definitions. */ EXPORT_TRACEPOINT_SYMBOL(kmalloc); EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); --=20 2.46.1.824.gd892dcdcdd-goog