1#!/bin/bash
2# probe libc's inet_pton & backtrace it with ping (exclusive)
3
4# Installs a probe on libc's inet_pton function, that will use uprobes,
5# then use 'perf trace' on a ping to localhost asking for just one packet
6# with the a backtrace 3 levels deep, check that it is what we expect.
7# This needs no debuginfo package, all is done using the libc ELF symtab
8# and the CFI info in the binaries.
9
10# SPDX-License-Identifier: GPL-2.0
11# Arnaldo Carvalho de Melo <acme@kernel.org>, 2017
12
13# shellcheck source=lib/probe.sh
14. "$(dirname "$0")/lib/probe.sh"
15# shellcheck source=lib/probe_vfs_getname.sh
16. "$(dirname "$0")/lib/probe_vfs_getname.sh"
17
18libc=$(grep -w libc /proc/self/maps | head -1 | sed -r 's/.*[[:space:]](\/.*)/\1/g')
19nm -Dg $libc 2>/dev/null | grep -F -q inet_pton || exit 254
20
21event_pattern='probe_libc:inet_pton(_[[:digit:]]+)?'
22
23add_libc_inet_pton_event() {
24
25	event_name=$(perf probe -f -x $libc -a inet_pton 2>&1 | tail -n +2 | head -n -5 | \
26			awk -v ep="$event_pattern" -v l="$libc" '$0 ~ ep && $0 ~ \
27			("\\(on inet_pton in " l "\\)") {print $1}')
28
29	if [ $? -ne 0 ] || [ -z "$event_name" ] ; then
30		printf "FAIL: could not add event\n"
31		return 1
32	fi
33}
34
35trace_libc_inet_pton_backtrace() {
36
37	expected=`mktemp -u /tmp/expected.XXX`
38
39	echo "ping[][0-9 \.:]+$event_name: \([[:xdigit:]]+\)" > $expected
40	echo ".*inet_pton\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$" >> $expected
41	case "$(uname -m)" in
42	s390x)
43		eventattr='call-graph=dwarf,max-stack=4'
44		echo "((__GI_)?getaddrinfo|text_to_binary_address)\+0x[[:xdigit:]]+[[:space:]]\($libc|inlined\)$" >> $expected
45		echo "(gaih_inet|main)\+0x[[:xdigit:]]+[[:space:]]\(inlined|.*/bin/ping.*\)$" >> $expected
46		;;
47	*)
48		eventattr='max-stack=4'
49		echo ".*(\+0x[[:xdigit:]]+|\[unknown\])[[:space:]]\(.*/bin/ping.*\)$" >> $expected
50		;;
51	esac
52
53	perf_data=`mktemp -u /tmp/perf.data.XXX`
54	perf_script=`mktemp -u /tmp/perf.script.XXX`
55
56	# Check presence of libtraceevent support to run perf record
57	skip_no_probe_record_support "$event_name/$eventattr/"
58	if [ $? -eq 2 ]; then
59		echo "WARN: Skipping test trace_libc_inet_pton_backtrace. No libtraceevent support."
60		return 2
61	fi
62
63	perf record -e $event_name/$eventattr/ -o $perf_data ping -6 -c 1 ::1 > /dev/null 2>&1
64	# check if perf data file got created in above step.
65	if [ ! -e $perf_data ]; then
66		printf "FAIL: perf record failed to create \"%s\" \n" "$perf_data"
67		return 1
68	fi
69	perf script -i $perf_data | tac | grep -m1 ^ping -B9 | tac > $perf_script
70
71	exec 4<$expected
72	while read -r pattern <&4; do
73		echo "Pattern: $pattern"
74		[ -z "$pattern" ] && break
75
76		found=0
77
78		# Search lines in the perf script result
79		exec 3<$perf_script
80		while read line <&3; do
81			[ -z "$line" ] && break
82			echo "  Matching: $line"
83			! echo "$line" | grep -E -q "$pattern"
84			found=$?
85			[ $found -eq 1 ] && break
86		done
87
88		if [ $found -ne 1 ] ; then
89			printf "FAIL: Didn't find the expected backtrace entry \"%s\"\n" "$pattern"
90			return 1
91		fi
92	done
93
94	# If any statements are executed from this point onwards,
95	# the exit code of the last among these will be reflected
96	# in err below. If the exit code is 0, the test will pass
97	# even if the perf script output does not match.
98}
99
100delete_libc_inet_pton_event() {
101
102	if [ -n "$event_name" ] ; then
103		perf probe -q -d $event_name
104	fi
105}
106
107# Check for IPv6 interface existence
108ip a sh lo | grep -F -q inet6 || exit 2
109[ "$(id -u)" = 0 ] || exit 2
110
111skip_if_no_perf_probe && \
112add_libc_inet_pton_event && \
113trace_libc_inet_pton_backtrace
114err=$?
115rm -f ${perf_data} ${perf_script} ${expected}
116delete_libc_inet_pton_event
117exit $err
118