From patchwork Thu Jun 4 09:10:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sumanth Korikkar X-Patchwork-Id: 1303385 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=none (p=none dis=none) header.from=linux.ibm.com Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49d0PY3hy7z9sSF for ; Thu, 4 Jun 2020 19:10:57 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726814AbgFDJK5 (ORCPT ); Thu, 4 Jun 2020 05:10:57 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:17858 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726603AbgFDJK4 (ORCPT ); Thu, 4 Jun 2020 05:10:56 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 05492dGI134053; Thu, 4 Jun 2020 05:10:55 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 31ek589e1m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 04 Jun 2020 05:10:55 -0400 Received: from m0098393.ppops.net (m0098393.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 05492ne4135041; Thu, 4 Jun 2020 05:10:54 -0400 Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 31ek589e0j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 04 Jun 2020 05:10:54 -0400 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 0549AQQF023550; Thu, 4 Jun 2020 09:10:52 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma03ams.nl.ibm.com with ESMTP id 31bf481nyq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 04 Jun 2020 09:10:52 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 0549AnVC57147826 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 4 Jun 2020 09:10:49 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 387ECA4069; Thu, 4 Jun 2020 09:10:49 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E158FA4065; Thu, 4 Jun 2020 09:10:48 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 4 Jun 2020 09:10:48 +0000 (GMT) From: Sumanth Korikkar To: linux-perf-users@vger.kernel.org, acme@kernel.org Cc: bpf@vger.kernel.org, jolsa@redhat.com, tmricht@linux.ibm.com, heiko.carstens@de.ibm.com, mhiramat@kernel.org, iii@linux.ibm.com, Sumanth Korikkar Subject: [PATCH] perf: Fix bpf prologue generation, user attribute access in kprobes Date: Thu, 4 Jun 2020 11:10:28 +0200 Message-Id: <20200604091028.101569-1-sumanthk@linux.ibm.com> X-Mailer: git-send-email 2.17.1 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216, 18.0.687 definitions=2020-06-04_05:2020-06-02,2020-06-04 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 suspectscore=0 adultscore=0 phishscore=0 bulkscore=0 clxscore=1011 mlxscore=0 malwarescore=0 cotscore=-2147483648 mlxlogscore=999 impostorscore=0 priorityscore=1501 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006040058 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Issues: 1. bpf_probe_read is no longer available for architecture which has overlapping address space. Hence bpf prologue generation fails 2. perf probe -a 'do_sched_setscheduler pid policy param->sched_priority@user' did not work before. Fixes: 1. Use bpf_probe_read_kernel for kernel member access. For user attribute access in kprobes, bpf_probe_read_user is utilized 2. Make (perf probe -a 'do_sched_setscheduler pid policy param->sched_priority@user') output equivalent to ftrace ('p:probe/do_sched_setscheduler _text+517384 pid=%r2:s32 policy=%r3:s32 sched_priority=+u0 (%r4):s32' > kprobe_events) Other: 1. Right now, __match_glob() does not handle [u]. For now, use *u]. 2. @user attribute was introduced in commit 1e032f7cfa14 ("perf-probe: Add user memory access attribute support") Test: 1. ulimit -l 128 ; ./perf record -e tests/bpf_sched_setscheduler.c 2. cat tests/bpf_sched_setscheduler.c static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) = (void *) 6; static int (*bpf_probe_read_user)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 112; static int (*bpf_probe_read_kernel)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 113; SEC("func=do_sched_setscheduler pid policy param->sched_priority@user") int bpf_func__setscheduler(void *ctx, int err, pid_t pid, int policy, int param) { char fmt[] = "prio: %ld"; bpf_trace_printk(fmt, sizeof(fmt), param); return 1; } char _license[] SEC("license") = "GPL"; int _version SEC("version") = LINUX_VERSION_CODE; 3. ./perf script sched 305669 [000] 1614458.838675: perf_bpf_probe:func: (2904e508) pid=261614 policy=2 sched_priority=1 4. cat /sys/kernel/debug/tracing/trace <...>-309956 [006] .... 1616098.093957: 0: prio: 1 5. bpf_probe_read_user is used when @user attribute is used. Otherwise, defaults to bpf_probe_read_kernel 6. ./perf test bpf (null_lseek - kernel member access) 42: BPF filter : 42.1: Basic BPF filtering : Ok 42.2: BPF pinning : Ok 42.3: BPF prologue generation : Ok 42.4: BPF relocation checker : FAILED! Signed-off-by: Sumanth Korikkar Reviewed-by: Thomas Richter Acked-by: Masami Hiramatsu --- tools/perf/util/bpf-prologue.c | 14 ++++++++++---- tools/perf/util/probe-event.c | 7 +++++-- tools/perf/util/probe-file.c | 2 +- 3 files changed, 16 insertions(+), 7 deletions(-) diff --git a/tools/perf/util/bpf-prologue.c b/tools/perf/util/bpf-prologue.c index b020a8678eb9..9887ae09242d 100644 --- a/tools/perf/util/bpf-prologue.c +++ b/tools/perf/util/bpf-prologue.c @@ -142,7 +142,8 @@ static int gen_read_mem(struct bpf_insn_pos *pos, int src_base_addr_reg, int dst_addr_reg, - long offset) + long offset, + int probeid) { /* mov arg3, src_base_addr_reg */ if (src_base_addr_reg != BPF_REG_ARG3) @@ -159,7 +160,7 @@ gen_read_mem(struct bpf_insn_pos *pos, ins(BPF_MOV64_REG(BPF_REG_ARG1, dst_addr_reg), pos); /* Call probe_read */ - ins(BPF_EMIT_CALL(BPF_FUNC_probe_read), pos); + ins(BPF_EMIT_CALL(probeid), pos); /* * Error processing: if read fail, goto error code, * will be relocated. Target should be the start of @@ -241,7 +242,7 @@ static int gen_prologue_slowpath(struct bpf_insn_pos *pos, struct probe_trace_arg *args, int nargs) { - int err, i; + int err, i, probeid; for (i = 0; i < nargs; i++) { struct probe_trace_arg *arg = &args[i]; @@ -276,11 +277,16 @@ gen_prologue_slowpath(struct bpf_insn_pos *pos, stack_offset), pos); ref = arg->ref; + probeid = BPF_FUNC_probe_read_kernel; while (ref) { pr_debug("prologue: arg %d: offset %ld\n", i, ref->offset); + + if (ref->user_access) + probeid = BPF_FUNC_probe_read_user; + err = gen_read_mem(pos, BPF_REG_3, BPF_REG_7, - ref->offset); + ref->offset, probeid); if (err) { pr_err("prologue: failed to generate probe_read function call\n"); goto errout; diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index eea132f512b0..7cdb66ef3baa 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -1565,7 +1565,7 @@ static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg) } tmp = strchr(str, '@'); - if (tmp && tmp != str && strcmp(tmp + 1, "user")) { /* user attr */ + if (tmp && tmp != str && !strcmp(tmp + 1, "user")) { /* user attr */ if (!user_access_is_supported()) { semantic_error("ftrace does not support user access\n"); return -EINVAL; @@ -1986,7 +1986,10 @@ static int __synthesize_probe_trace_arg_ref(struct probe_trace_arg_ref *ref, if (depth < 0) return depth; } - err = strbuf_addf(buf, "%+ld(", ref->offset); + if (ref->user_access) + err = strbuf_addf(buf, "%s%ld(", "+u", ref->offset); + else + err = strbuf_addf(buf, "%+ld(", ref->offset); return (err < 0) ? err : depth; } diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c index 8c852948513e..064b63a6a3f3 100644 --- a/tools/perf/util/probe-file.c +++ b/tools/perf/util/probe-file.c @@ -1044,7 +1044,7 @@ static struct { DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"), DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"), DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"), - DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*[u]*"), + DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*u]*"), DEFINE_TYPE(FTRACE_README_MULTIPROBE_EVENT, "*Create/append/*"), DEFINE_TYPE(FTRACE_README_IMMEDIATE_VALUE, "*\\imm-value,*"), };