From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9AC1C433E0 for ; Tue, 9 Jun 2020 07:00:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8ABB52074B for ; Tue, 9 Jun 2020 07:00:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727842AbgFIHA5 (ORCPT ); Tue, 9 Jun 2020 03:00:57 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:61592 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727021AbgFIHA4 (ORCPT ); Tue, 9 Jun 2020 03:00:56 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0596VpAE123568; Tue, 9 Jun 2020 03:00:55 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 31huupq45b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 09 Jun 2020 03:00:54 -0400 Received: from m0098410.ppops.net (m0098410.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 0596WCp4125039; Tue, 9 Jun 2020 03:00:53 -0400 Received: from ppma01fra.de.ibm.com (46.49.7a9f.ip4.static.sl-reverse.com [159.122.73.70]) by mx0a-001b2d01.pphosted.com with ESMTP id 31huupq43m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 09 Jun 2020 03:00:53 -0400 Received: from pps.filterd (ppma01fra.de.ibm.com [127.0.0.1]) by ppma01fra.de.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 0596pAWt013446; Tue, 9 Jun 2020 07:00:51 GMT Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by ppma01fra.de.ibm.com with ESMTP id 31g2s7t731-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 09 Jun 2020 07:00:51 +0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 05970mgB46202912 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 9 Jun 2020 07:00:48 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 354794204C; Tue, 9 Jun 2020 07:00:48 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CF75842057; Tue, 9 Jun 2020 07:00:47 +0000 (GMT) Received: from localhost.localdomain (unknown [9.145.50.94]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 9 Jun 2020 07:00:47 +0000 (GMT) Subject: Re: [PATCH] perf: Fix bpf prologue generation, user attribute access in kprobes To: Arnaldo Carvalho de Melo Cc: linux-perf-users@vger.kernel.org, bpf@vger.kernel.org, jolsa@redhat.com, tmricht@linux.ibm.com, heiko.carstens@de.ibm.com, mhiramat@kernel.org, iii@linux.ibm.com References: <20200604091028.101569-1-sumanthk@linux.ibm.com> <20200608164327.GD3073@kernel.org> From: Sumanth Korikkar Message-ID: Date: Tue, 9 Jun 2020 09:00:47 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200608164327.GD3073@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-09_01:2020-06-08,2020-06-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 cotscore=-2147483648 suspectscore=0 mlxscore=0 bulkscore=0 impostorscore=0 mlxlogscore=999 phishscore=0 clxscore=1015 spamscore=0 priorityscore=1501 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006090046 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Hi Arnaldo, On 6/8/20 6:43 PM, Arnaldo Carvalho de Melo wrote: > Em Thu, Jun 04, 2020 at 11:10:28AM +0200, Sumanth Korikkar escreveu: >> 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. > This looks super nice, thanks for working on this! > > But please split this into multiple patches, one for the 'perf probe' > part, add the Acked-by provided by Masami to that one, and the other for > the part fixing the lack of bpf_probe_read(), ok? Thank you. Ok sure. I will send the split patches. Best Regards Sumanth > > Thanks! > > - Arnaldo > >> 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 >> --- >> 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,*"), >> }; >> -- >> 2.25.4 >> -- Sumanth Korikkar