From patchwork Tue Jan 11 17:25:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 12710163 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E5FBC433F5 for ; Tue, 11 Jan 2022 17:26:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344201AbiAKR0o (ORCPT ); Tue, 11 Jan 2022 12:26:44 -0500 Received: from linux.microsoft.com ([13.77.154.182]:33936 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344189AbiAKR0f (ORCPT ); Tue, 11 Jan 2022 12:26:35 -0500 Received: from localhost.localdomain (c-73-140-2-214.hsd1.wa.comcast.net [73.140.2.214]) by linux.microsoft.com (Postfix) with ESMTPSA id BC82820B7187; Tue, 11 Jan 2022 09:26:32 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com BC82820B7187 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1641921992; bh=Os5S5371BbotyCNO6tkuc3u978dmxAt5ZLUCv5azWLM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jhctxNtIyQ1TMqClIjMRgvAO+zK0tiOnp8CbqGdQSoX+32b2LX8yjPWPjMUvjt5CJ n4NIVKZsQ5lHjutVAdXZhhwVmH+5NhkPJ93Tt7Qqt53Tr4R3QM2YrhnW42m/YxOdQr 4trfD9/Ol399L6vTnlJ8PYApbcxYom8VZMKXkeDU= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org Cc: linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org, beaub@linux.microsoft.com Subject: [PATCH v9 05/12] user_events: Optimize writing events by only copying data once Date: Tue, 11 Jan 2022 09:25:55 -0800 Message-Id: <20220111172602.2513-6-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220111172602.2513-1-beaub@linux.microsoft.com> References: <20220111172602.2513-1-beaub@linux.microsoft.com> Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Pass iterator through to probes to allow copying data directly to the probe buffers instead of taking multiple copies. Enables eBPF user and raw iterator types out to programs for no-copy scenarios. Signed-off-by: Beau Belgrave --- kernel/trace/trace_events_user.c | 115 +++++++++++++++++++++++-------- 1 file changed, 85 insertions(+), 30 deletions(-) diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 966dfb4fdc8d..e4b166cba1bb 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -41,6 +41,9 @@ #define MAX_FIELD_ARRAY_SIZE 1024 #define MAX_FIELD_ARG_NAME 256 +#define MAX_BPF_COPY_SIZE PAGE_SIZE +#define MAX_STACK_BPF_DATA 512 + static char *register_page_data; static DEFINE_MUTEX(reg_mutex); @@ -78,8 +81,7 @@ struct user_event_refs { struct user_event *events[]; }; -typedef void (*user_event_func_t) (struct user_event *user, - void *data, u32 datalen, +typedef void (*user_event_func_t) (struct user_event *user, struct iov_iter *i, void *tpdata); static int user_event_parse(char *name, char *args, char *flags, @@ -90,6 +92,20 @@ static u32 user_event_key(char *name) return jhash(name, strlen(name), 0); } +static __always_inline __must_check +size_t copy_nofault(void *addr, size_t bytes, struct iov_iter *i) +{ + size_t ret; + + pagefault_disable(); + + ret = copy_from_iter_nocache(addr, bytes, i); + + pagefault_enable(); + + return ret; +} + static struct list_head *user_event_get_fields(struct trace_event_call *call) { struct user_event *user = (struct user_event *)call->data; @@ -525,7 +541,7 @@ static struct user_event *find_user_event(char *name, u32 *outkey) /* * Writes the user supplied payload out to a trace file. */ -static void user_event_ftrace(struct user_event *user, void *data, u32 datalen, +static void user_event_ftrace(struct user_event *user, struct iov_iter *i, void *tpdata) { struct trace_event_file *file; @@ -541,41 +557,83 @@ static void user_event_ftrace(struct user_event *user, void *data, u32 datalen, /* Allocates and fills trace_entry, + 1 of this is data payload */ entry = trace_event_buffer_reserve(&event_buffer, file, - sizeof(*entry) + datalen); + sizeof(*entry) + i->count); if (unlikely(!entry)) return; - memcpy(entry + 1, data, datalen); - - trace_event_buffer_commit(&event_buffer); + if (unlikely(!copy_nofault(entry + 1, i->count, i))) + __trace_event_discard_commit(event_buffer.buffer, + event_buffer.event); + else + trace_event_buffer_commit(&event_buffer); } #ifdef CONFIG_PERF_EVENTS +static void user_event_bpf(struct user_event *user, struct iov_iter *i) +{ + struct user_bpf_context context; + struct user_bpf_iter bpf_i; + char fast_data[MAX_STACK_BPF_DATA]; + void *temp = NULL; + + if ((user->flags & FLAG_BPF_ITER) && iter_is_iovec(i)) { + /* Raw iterator */ + context.data_type = USER_BPF_DATA_ITER; + context.data_len = i->count; + context.iter = &bpf_i; + + bpf_i.iov_offset = i->iov_offset; + bpf_i.iov = i->iov; + bpf_i.nr_segs = i->nr_segs; + } else if (i->nr_segs == 1 && iter_is_iovec(i)) { + /* Single buffer from user */ + context.data_type = USER_BPF_DATA_USER; + context.data_len = i->count; + context.udata = i->iov->iov_base + i->iov_offset; + } else { + /* Multi buffer from user */ + struct iov_iter copy = *i; + size_t copy_size = min_t(size_t, i->count, MAX_BPF_COPY_SIZE); + + context.data_type = USER_BPF_DATA_KERNEL; + context.kdata = fast_data; + + if (unlikely(copy_size > sizeof(fast_data))) { + temp = kmalloc(copy_size, GFP_NOWAIT); + + if (temp) + context.kdata = temp; + else + copy_size = sizeof(fast_data); + } + + context.data_len = copy_nofault(context.kdata, + copy_size, ©); + } + + trace_call_bpf(&user->call, &context); + + kfree(temp); +} + /* * Writes the user supplied payload out to perf ring buffer or eBPF program. */ -static void user_event_perf(struct user_event *user, void *data, u32 datalen, +static void user_event_perf(struct user_event *user, struct iov_iter *i, void *tpdata) { struct hlist_head *perf_head; - if (bpf_prog_array_valid(&user->call)) { - struct user_bpf_context context = {0}; - - context.data_len = datalen; - context.data_type = USER_BPF_DATA_KERNEL; - context.kdata = data; - - trace_call_bpf(&user->call, &context); - } + if (bpf_prog_array_valid(&user->call)) + user_event_bpf(user, i); perf_head = this_cpu_ptr(user->call.perf_events); if (perf_head && !hlist_empty(perf_head)) { struct trace_entry *perf_entry; struct pt_regs *regs; - size_t size = sizeof(*perf_entry) + datalen; + size_t size = sizeof(*perf_entry) + i->count; int context; perf_entry = perf_trace_buf_alloc(ALIGN(size, 8), @@ -586,7 +644,10 @@ static void user_event_perf(struct user_event *user, void *data, u32 datalen, perf_fetch_caller_regs(regs); - memcpy(perf_entry + 1, data, datalen); + if (unlikely(!copy_nofault(perf_entry + 1, i->count, i))) { + perf_swevent_put_recursion_context(context); + return; + } perf_trace_buf_submit(perf_entry, size, context, user->call.event.type, 1, regs, @@ -1019,16 +1080,11 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i) if (likely(atomic_read(&tp->key.enabled) > 0)) { struct tracepoint_func *probe_func_ptr; user_event_func_t probe_func; + struct iov_iter copy; void *tpdata; - void *kdata; - u32 datalen; - kdata = kmalloc(i->count, GFP_KERNEL); - - if (unlikely(!kdata)) - return -ENOMEM; - - datalen = copy_from_iter(kdata, i->count, i); + if (unlikely(fault_in_iov_iter_readable(i, i->count))) + return -EFAULT; rcu_read_lock_sched(); @@ -1036,15 +1092,14 @@ static ssize_t user_events_write_core(struct file *file, struct iov_iter *i) if (probe_func_ptr) { do { + copy = *i; probe_func = probe_func_ptr->func; tpdata = probe_func_ptr->data; - probe_func(user, kdata, datalen, tpdata); + probe_func(user, ©, tpdata); } while ((++probe_func_ptr)->func); } rcu_read_unlock_sched(); - - kfree(kdata); } return ret;