record+probe_libc_inet_pton.sh

  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