From patchwork Fri Dec 20 06:00:07 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 13916275 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 67D011A8419; Fri, 20 Dec 2024 06:00:13 +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=1734674413; cv=none; b=sGv4ThvntRxB+FGGW7+xvjjusdEXVkLr9OGslp06upIIAGNjs/WwajoexAN8z3PkCQEd14arBX4ZBIeXsNH+EF4uZKbdoHWThCjqR5jaPyYXYPJPNBvUedA+ZPmUufL65V9+PAwPrmuF1dWI/5ATX8Vx3781Y2UglUNgHu6C/w8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734674413; c=relaxed/simple; bh=DciWbf1YOrFnvHGsJrdBvx3igukTjFBexecfLRIhP8E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DT8cbIkEKoLJAxFMheay8s5n71lsR9Pjk1m04XAWV+YydmhvT11qSQcZpkyzKNpiigt/Silss8lQhWDvNA4Bu6X9Mq+akWl+iF8/r1+IQ6/+R2J4o0mF5P3oQO9I3JF4V+q5IkYFKTtLZtH73H2uAKGy8PFsG0gFKXsi3PfRths= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JMLYhe56; 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="JMLYhe56" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 30B99C4CEE8; Fri, 20 Dec 2024 06:00:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734674412; bh=DciWbf1YOrFnvHGsJrdBvx3igukTjFBexecfLRIhP8E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JMLYhe56DLnky7/VDqgXfcLEqTj8upQSLc5oKi7VGyXpMSWTLaeNACvr0Q3xlEr4v AxMlbNOzUP3LoEQe+2i+urjXTf/iso1f6D+PxY6BaS0HMidK7ShlnkiMBeANN+i23F FSOKJtYJnD47rHThGFOGz2aOTiIbnGv1795gHM5QVN4DEPPfbbVvHA5qVP/fd91PhL wTOQEz3bE3lW6C0ItgT5ygiNyWnb2T1YLobXpcBT0ffLQcolEQG5O5gzSKcHHNejpP BnzLPlKB28amz1ks0OeiljqWKwVX3WjqoQGzVQs7siNK0NlmTF9o+OwkLjqTBz0IDG W+nfTl+osemWw== From: Namhyung Kim To: Arnaldo Carvalho de Melo , Ian Rogers , Kan Liang Cc: Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Andrii Nakryiko , Song Liu , bpf@vger.kernel.org, Stephane Eranian , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Kees Cook , Chun-Tse Shao Subject: [PATCH v3 2/4] perf lock contention: Run BPF slab cache iterator Date: Thu, 19 Dec 2024 22:00:07 -0800 Message-ID: <20241220060009.507297-3-namhyung@kernel.org> X-Mailer: git-send-email 2.47.1.613.gc27f4b7a9f-goog In-Reply-To: <20241220060009.507297-1-namhyung@kernel.org> References: <20241220060009.507297-1-namhyung@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Recently the kernel got the kmem_cache iterator to traverse metadata of slab objects. This can be used to symbolize dynamic locks in a slab. The new slab_caches hash map will have the pointer of the kmem_cache as a key and save the name and a id. The id will be saved in the flags part of the lock. Acked-by: Ian Rogers Signed-off-by: Namhyung Kim --- tools/perf/util/bpf_lock_contention.c | 50 +++++++++++++++++++ .../perf/util/bpf_skel/lock_contention.bpf.c | 48 ++++++++++++++++++ tools/perf/util/bpf_skel/lock_data.h | 12 +++++ tools/perf/util/bpf_skel/vmlinux/vmlinux.h | 8 +++ 4 files changed, 118 insertions(+) diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c index 37e17c56f1064e60..169531d1865264be 100644 --- a/tools/perf/util/bpf_lock_contention.c +++ b/tools/perf/util/bpf_lock_contention.c @@ -12,12 +12,59 @@ #include #include #include +#include #include #include "bpf_skel/lock_contention.skel.h" #include "bpf_skel/lock_data.h" static struct lock_contention_bpf *skel; +static bool has_slab_iter; + +static void check_slab_cache_iter(struct lock_contention *con) +{ + struct btf *btf = btf__load_vmlinux_btf(); + s32 ret; + + if (btf == NULL) { + pr_debug("BTF loading failed: %s\n", strerror(errno)); + return; + } + + ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT); + if (ret < 0) { + bpf_program__set_autoload(skel->progs.slab_cache_iter, false); + pr_debug("slab cache iterator is not available: %d\n", ret); + goto out; + } + + has_slab_iter = true; + + bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries); +out: + btf__free(btf); +} + +static void run_slab_cache_iter(void) +{ + int fd; + char buf[256]; + + if (!has_slab_iter) + return; + + fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter)); + if (fd < 0) { + pr_debug("cannot create slab cache iter: %d\n", fd); + return; + } + + /* This will run the bpf program */ + while (read(fd, buf, sizeof(buf)) > 0) + continue; + + close(fd); +} int lock_contention_prepare(struct lock_contention *con) { @@ -109,6 +156,8 @@ int lock_contention_prepare(struct lock_contention *con) skel->rodata->use_cgroup_v2 = 1; } + check_slab_cache_iter(con); + if (lock_contention_bpf__load(skel) < 0) { pr_err("Failed to load lock-contention BPF skeleton\n"); return -1; @@ -304,6 +353,7 @@ static void account_end_timestamp(struct lock_contention *con) int lock_contention_start(void) { + run_slab_cache_iter(); skel->bss->enabled = 1; return 0; } diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c index 1069bda5d733887f..bed446c42561d8bf 100644 --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c @@ -100,6 +100,13 @@ struct { __uint(max_entries, 1); } cgroup_filter SEC(".maps"); +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(long)); + __uint(value_size, sizeof(struct slab_cache_data)); + __uint(max_entries, 1); +} slab_caches SEC(".maps"); + struct rw_semaphore___old { struct task_struct *owner; } __attribute__((preserve_access_index)); @@ -136,6 +143,8 @@ int perf_subsys_id = -1; __u64 end_ts; +__u32 slab_cache_id; + /* error stat */ int task_fail; int stack_fail; @@ -563,4 +572,43 @@ int BPF_PROG(end_timestamp) return 0; } +/* + * bpf_iter__kmem_cache added recently so old kernels don't have it in the + * vmlinux.h. But we cannot add it here since it will cause a compiler error + * due to redefinition of the struct on later kernels. + * + * So it uses a CO-RE trick to access the member only if it has the type. + * This will support both old and new kernels without compiler errors. + */ +struct bpf_iter__kmem_cache___new { + struct kmem_cache *s; +} __attribute__((preserve_access_index)); + +SEC("iter/kmem_cache") +int slab_cache_iter(void *ctx) +{ + struct kmem_cache *s = NULL; + struct slab_cache_data d; + const char *nameptr; + + if (bpf_core_type_exists(struct bpf_iter__kmem_cache)) { + struct bpf_iter__kmem_cache___new *iter = ctx; + + s = BPF_CORE_READ(iter, s); + } + + if (s == NULL) + return 0; + + nameptr = BPF_CORE_READ(s, name); + bpf_probe_read_kernel_str(d.name, sizeof(d.name), nameptr); + + d.id = ++slab_cache_id << LCB_F_SLAB_ID_SHIFT; + if (d.id >= LCB_F_SLAB_ID_END) + return 0; + + bpf_map_update_elem(&slab_caches, &s, &d, BPF_NOEXIST); + return 0; +} + char LICENSE[] SEC("license") = "Dual BSD/GPL"; diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h index 4f0aae5483745dfa..c15f734d7fc4aecb 100644 --- a/tools/perf/util/bpf_skel/lock_data.h +++ b/tools/perf/util/bpf_skel/lock_data.h @@ -32,9 +32,16 @@ struct contention_task_data { #define LCD_F_MMAP_LOCK (1U << 31) #define LCD_F_SIGHAND_LOCK (1U << 30) +#define LCB_F_SLAB_ID_SHIFT 16 +#define LCB_F_SLAB_ID_START (1U << 16) +#define LCB_F_SLAB_ID_END (1U << 26) +#define LCB_F_SLAB_ID_MASK 0x03FF0000U + #define LCB_F_TYPE_MAX (1U << 7) #define LCB_F_TYPE_MASK 0x0000007FU +#define SLAB_NAME_MAX 28 + struct contention_data { u64 total_time; u64 min_time; @@ -55,4 +62,9 @@ enum lock_class_sym { LOCK_CLASS_RQLOCK, }; +struct slab_cache_data { + u32 id; + char name[SLAB_NAME_MAX]; +}; + #endif /* UTIL_BPF_SKEL_LOCK_DATA_H */ diff --git a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h index 4dcad7b682bdee9c..7b81d3173917fdb5 100644 --- a/tools/perf/util/bpf_skel/vmlinux/vmlinux.h +++ b/tools/perf/util/bpf_skel/vmlinux/vmlinux.h @@ -195,4 +195,12 @@ struct bpf_perf_event_data_kern { */ struct rq {}; +struct kmem_cache { + const char *name; +} __attribute__((preserve_access_index)); + +struct bpf_iter__kmem_cache { + struct kmem_cache *s; +} __attribute__((preserve_access_index)); + #endif // __VMLINUX_H