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Thu, 17 Oct 2024 08:06:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729152365; bh=xhFeg8d3ZWTLiCtqZ3vBuXhl5x01QSY54MvjjIElYqk=; h=From:To:Cc:Subject:Date:From; b=K7efwpBAPFGbHuhzunUc2QaAoYXQGvgJ0Z4GkctsmDARFen9LFPnov4tOVlsL6ajn MtuBCbLOr705HX4kPXojoTFNYCmqyUJT3cw4vFplqwBkkjUfQosAWmp/xO3VD0Ayby Nys6vuOCh5t7WOYofWupYigpR6FTnYZILFI7c0ndK+NtB+b+k7NBvhLniC/rdQ/2dh P9jlEzaK3mO2wPV6ioY6EO4S9W/Vyz7tJ+/CZ2uvTcmStDfck+WCcO9DA60ZgpMeHL c8OVaEOWifVvOh8F00/dqILMx00M3QektgYxY5yGXqFZK9R82GHrh9cG5n3qluMTaQ miQ6c5PJmvWug== 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 bpf-next 1/2] bpf: Add open coded version of kmem_cache iterator Date: Thu, 17 Oct 2024 01:06:03 -0700 Message-ID: <20241017080604.541872-1-namhyung@kernel.org> X-Mailer: git-send-email 2.47.0.rc1.288.g06298d1525-goog MIME-Version: 1.0 X-Rspamd-Queue-Id: 10EBE40012 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 9qnpqe61g45angfcpnqgxtucj9m81xmh X-HE-Tag: 1729152356-318167 X-HE-Meta: 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 EQXc1rsu k4jvw4vioTuZeUoaxBGz6sN7OT2Hv4oc1R6Y7GIuZz0j/yU6LnHWh068NVvV755MWunyaekD3Rb3VH/eThO5R5CcpK4t81AnGNG59GXglh/qtvl4Q5zwi5SQXJoMt6FhqQUQNgxyar6n2O7PZ0oXzzbeJTY58bN9pCVfRWdKSaeTS9WXm/lUg8DlGrc1ip5GLVwc0lEMFyjSvq0i5/6AN55MEsne49DF5w7jbnvUrrQSNt+HOScsbM/4e68RLwpnot+o+Pi76W2Vyk8XAz14CTUmkUKUWntVyBv5jwgO12VVlEgOXSGESd77dTI90decMaNN/P7OgyoVhTJ6AyaaTATYa61N2qACewS5e X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Add a new open coded iterator for kmem_cache which can be called from a BPF program like below. It doesn't take any argument and traverses all kmem_cache entries. struct kmem_cache *pos; bpf_for_each(kmem_cache, pos) { ... } As it needs to grab slab_mutex, it should be called from sleepable BPF programs only. Signed-off-by: Namhyung Kim --- kernel/bpf/helpers.c | 3 ++ kernel/bpf/kmem_cache_iter.c | 87 ++++++++++++++++++++++++++++++++++++ 2 files changed, 90 insertions(+) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 073e6f04f4d765ff..d1dfa4f335577914 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -3111,6 +3111,9 @@ 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) +BTF_ID_FLAGS(func, bpf_iter_kmem_cache_new, KF_ITER_NEW | KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_iter_kmem_cache_next, KF_ITER_NEXT | KF_RET_NULL | KF_SLEEPABLE) +BTF_ID_FLAGS(func, bpf_iter_kmem_cache_destroy, KF_ITER_DESTROY | KF_SLEEPABLE) BTF_KFUNCS_END(common_btf_ids) static const struct btf_kfunc_id_set common_kfunc_set = { diff --git a/kernel/bpf/kmem_cache_iter.c b/kernel/bpf/kmem_cache_iter.c index ebc101d7da51b57c..31ddaf452b20a458 100644 --- a/kernel/bpf/kmem_cache_iter.c +++ b/kernel/bpf/kmem_cache_iter.c @@ -145,6 +145,93 @@ static const struct bpf_iter_seq_info kmem_cache_iter_seq_info = { .seq_ops = &kmem_cache_iter_seq_ops, }; +/* open-coded version */ +struct bpf_iter_kmem_cache { + __u64 __opaque[1]; +} __attribute__((aligned(8))); + +struct bpf_iter_kmem_cache_kern { + struct kmem_cache *pos; +} __attribute__((aligned(8))); + +__bpf_kfunc_start_defs(); + +__bpf_kfunc int bpf_iter_kmem_cache_new(struct bpf_iter_kmem_cache *it) +{ + struct bpf_iter_kmem_cache_kern *kit = (void *)it; + + BUILD_BUG_ON(sizeof(*kit) > sizeof(*it)); + BUILD_BUG_ON(__alignof__(*kit) != __alignof__(*it)); + + kit->pos = NULL; + return 0; +} + +__bpf_kfunc struct kmem_cache *bpf_iter_kmem_cache_next(struct bpf_iter_kmem_cache *it) +{ + struct bpf_iter_kmem_cache_kern *kit = (void *)it; + struct kmem_cache *prev = kit->pos; + struct kmem_cache *next; + bool destroy = false; + + mutex_lock(&slab_mutex); + + if (list_empty(&slab_caches)) { + mutex_unlock(&slab_mutex); + return NULL; + } + + if (prev == NULL) + next = list_first_entry(&slab_caches, struct kmem_cache, list); + else if (list_last_entry(&slab_caches, struct kmem_cache, list) == prev) + next = NULL; + else + next = list_next_entry(prev, list); + + /* boot_caches have negative refcount, don't touch them */ + if (next && next->refcount > 0) + next->refcount++; + + /* Skip kmem_cache_destroy() for active entries */ + if (prev && prev->refcount > 1) + prev->refcount--; + else if (prev && prev->refcount == 1) + destroy = true; + + mutex_unlock(&slab_mutex); + + if (destroy) + kmem_cache_destroy(prev); + + kit->pos = next; + return next; +} + +__bpf_kfunc void bpf_iter_kmem_cache_destroy(struct bpf_iter_kmem_cache *it) +{ + struct bpf_iter_kmem_cache_kern *kit = (void *)it; + struct kmem_cache *s = kit->pos; + bool destroy = false; + + if (s == NULL) + return; + + mutex_lock(&slab_mutex); + + /* Skip kmem_cache_destroy() for active entries */ + if (s->refcount > 1) + s->refcount--; + else if (s->refcount == 1) + destroy = true; + + mutex_unlock(&slab_mutex); + + if (destroy) + kmem_cache_destroy(s); +} + +__bpf_kfunc_end_defs(); + static void bpf_iter_kmem_cache_show_fdinfo(const struct bpf_iter_aux_info *aux, struct seq_file *seq) {