From patchwork Mon Jul 13 11:52:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alan Maguire X-Patchwork-Id: 1327911 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=oracle.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=oracle.com header.i=@oracle.com header.a=rsa-sha256 header.s=corp-2020-01-29 header.b=Teqn0wLq; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4B52CZ4qY1z9sRN for ; Mon, 13 Jul 2020 21:55:37 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729578AbgGMLzh (ORCPT ); Mon, 13 Jul 2020 07:55:37 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:59358 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729613AbgGMLzh (ORCPT ); Mon, 13 Jul 2020 07:55:37 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06DBq27C030635; Mon, 13 Jul 2020 11:54:52 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2020-01-29; bh=q9XY0O9VNOoVVMsxnoaHwNhhpztYHwFwPYqqNlIdYC4=; b=Teqn0wLq3Oa48MyWdCNgFk8lvHsNg1uMBBCvb9Yc7vD2yYcATgLjQLFIVJChyyyajtao zNS7GfaQJEISkXMEHQD+AYsKjOBRq9vprn7ihrgIyTxRmehACrFH2C6wmgZAxuzPPTtb pV6ZKsAyosyVghw3f5o5LR0qeqwTyEyx/knItHTeUIskDwDKHn5qPVcKdDX3WlgFLNAs 22dykDKADsFNxEAMmAOHPKyMpX4fVniAgjjPAp5mlOhjCZUKFBsdwBMN3py/9AJEYv2/ MujJv4/Sp6WDMFgHVi89Fzcg5n58ycwNkeKpMtC8knKAZFKW+qNyM1Os4NuT1w/ZbnPa iw== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2130.oracle.com with ESMTP id 3274uqxk8p-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 13 Jul 2020 11:54:52 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 06DBhgwU104109; Mon, 13 Jul 2020 11:52:51 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 327qb0epev-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 13 Jul 2020 11:52:51 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 06DBqoYM020293; Mon, 13 Jul 2020 11:52:50 GMT Received: from localhost.uk.oracle.com (/10.175.215.251) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 13 Jul 2020 04:52:50 -0700 From: Alan Maguire To: rostedt@goodmis.org, mingo@redhat.com, ast@kernel.org, daniel@iogearbox.net Cc: kafai@fb.com, songliubraving@fb.com, yhs@fb.com, andriin@fb.com, john.fastabend@gmail.com, kpsingh@chromium.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Alan Maguire Subject: [PATCH v3 bpf-next 1/2] bpf: use dedicated bpf_trace_printk event instead of trace_printk() Date: Mon, 13 Jul 2020 12:52:33 +0100 Message-Id: <1594641154-18897-2-git-send-email-alan.maguire@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1594641154-18897-1-git-send-email-alan.maguire@oracle.com> References: <1594641154-18897-1-git-send-email-alan.maguire@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9680 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 malwarescore=0 mlxscore=0 spamscore=0 phishscore=0 suspectscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007130088 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9680 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 impostorscore=0 suspectscore=0 phishscore=0 spamscore=0 mlxlogscore=999 malwarescore=0 mlxscore=0 priorityscore=1501 adultscore=0 bulkscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007130089 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org The bpf helper bpf_trace_printk() uses trace_printk() under the hood. This leads to an alarming warning message originating from trace buffer allocation which occurs the first time a program using bpf_trace_printk() is loaded. We can instead create a trace event for bpf_trace_printk() and enable it in-kernel when/if we encounter a program using the bpf_trace_printk() helper. With this approach, trace_printk() is not used directly and no warning message appears. This work was started by Steven (see Link) and finished by Alan; added Steven's Signed-off-by with his permission. Link: https://lore.kernel.org/r/20200628194334.6238b933@oasis.local.home Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Alan Maguire Acked-by: Andrii Nakryiko --- kernel/trace/Makefile | 2 ++ kernel/trace/bpf_trace.c | 42 +++++++++++++++++++++++++++++++++++++----- kernel/trace/bpf_trace.h | 34 ++++++++++++++++++++++++++++++++++ 3 files changed, 73 insertions(+), 5 deletions(-) create mode 100644 kernel/trace/bpf_trace.h diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 6575bb0..aeba5ee 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -31,6 +31,8 @@ ifdef CONFIG_GCOV_PROFILE_FTRACE GCOV_PROFILE := y endif +CFLAGS_bpf_trace.o := -I$(src) + CFLAGS_trace_benchmark.o := -I$(src) CFLAGS_trace_events_filter.o := -I$(src) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index e0b7775..0a2716d 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -19,6 +20,9 @@ #include "trace_probe.h" #include "trace.h" +#define CREATE_TRACE_POINTS +#include "bpf_trace.h" + #define bpf_event_rcu_dereference(p) \ rcu_dereference_protected(p, lockdep_is_held(&bpf_event_mutex)) @@ -374,6 +378,30 @@ static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype, } } +static DEFINE_RAW_SPINLOCK(trace_printk_lock); + +#define BPF_TRACE_PRINTK_SIZE 1024 + +static inline __printf(1, 0) int bpf_do_trace_printk(const char *fmt, ...) +{ + static char buf[BPF_TRACE_PRINTK_SIZE]; + unsigned long flags; + va_list ap; + int ret; + + raw_spin_lock_irqsave(&trace_printk_lock, flags); + va_start(ap, fmt); + ret = vsnprintf(buf, sizeof(buf), fmt, ap); + va_end(ap); + /* vsnprintf() will not append null for zero-length strings */ + if (ret == 0) + buf[0] = '\0'; + trace_bpf_trace_printk(buf); + raw_spin_unlock_irqrestore(&trace_printk_lock, flags); + + return ret; +} + /* * Only limited trace_printk() conversion specifiers allowed: * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pB %pks %pus %s @@ -483,8 +511,7 @@ static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype, */ #define __BPF_TP_EMIT() __BPF_ARG3_TP() #define __BPF_TP(...) \ - __trace_printk(0 /* Fake ip */, \ - fmt, ##__VA_ARGS__) + bpf_do_trace_printk(fmt, ##__VA_ARGS__) #define __BPF_ARG1_TP(...) \ ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \ @@ -521,10 +548,15 @@ static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype, const struct bpf_func_proto *bpf_get_trace_printk_proto(void) { /* - * this program might be calling bpf_trace_printk, - * so allocate per-cpu printk buffers + * This program might be calling bpf_trace_printk, + * so enable the associated bpf_trace/bpf_trace_printk event. + * Repeat this each time as it is possible a user has + * disabled bpf_trace_printk events. By loading a program + * calling bpf_trace_printk() however the user has expressed + * the intent to see such events. */ - trace_printk_init_buffers(); + if (trace_set_clr_event("bpf_trace", "bpf_trace_printk", 1)) + pr_warn_ratelimited("could not enable bpf_trace_printk events"); return &bpf_trace_printk_proto; } diff --git a/kernel/trace/bpf_trace.h b/kernel/trace/bpf_trace.h new file mode 100644 index 0000000..9acbc11 --- /dev/null +++ b/kernel/trace/bpf_trace.h @@ -0,0 +1,34 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM bpf_trace + +#if !defined(_TRACE_BPF_TRACE_H) || defined(TRACE_HEADER_MULTI_READ) + +#define _TRACE_BPF_TRACE_H + +#include + +TRACE_EVENT(bpf_trace_printk, + + TP_PROTO(const char *bpf_string), + + TP_ARGS(bpf_string), + + TP_STRUCT__entry( + __string(bpf_string, bpf_string) + ), + + TP_fast_assign( + __assign_str(bpf_string, bpf_string); + ), + + TP_printk("%s", __get_str(bpf_string)) +); + +#endif /* _TRACE_BPF_TRACE_H */ + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH . +#define TRACE_INCLUDE_FILE bpf_trace + +#include