Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1#!/bin/sh
2# Check branch stack sampling
3
4# SPDX-License-Identifier: GPL-2.0
5# German Gomez <german.gomez@arm.com>, 2022
6
7# we need a C compiler to build the test programs
8# so bail if none is found
9if ! [ -x "$(command -v cc)" ]; then
10 echo "failed: no compiler, install gcc"
11 exit 2
12fi
13
14# skip the test if the hardware doesn't support branch stack sampling
15perf record -b -o- -B true > /dev/null 2>&1 || exit 2
16
17TMPDIR=$(mktemp -d /tmp/__perf_test.program.XXXXX)
18
19cleanup() {
20 rm -rf $TMPDIR
21}
22
23trap cleanup exit term int
24
25gen_test_program() {
26 # generate test program
27 cat << EOF > $1
28#define BENCH_RUNS 999999
29int cnt;
30void bar(void) {
31} /* return */
32void foo(void) {
33 bar(); /* call */
34} /* return */
35void bench(void) {
36 void (*foo_ind)(void) = foo;
37 if ((cnt++) % 3) /* branch (cond) */
38 foo(); /* call */
39 bar(); /* call */
40 foo_ind(); /* call (ind) */
41}
42int main(void)
43{
44 int cnt = 0;
45 while (1) {
46 if ((cnt++) > BENCH_RUNS)
47 break;
48 bench(); /* call */
49 } /* branch (uncond) */
50 return 0;
51}
52EOF
53}
54
55test_user_branches() {
56 echo "Testing user branch stack sampling"
57
58 gen_test_program "$TEMPDIR/program.c"
59 cc -fno-inline -g "$TEMPDIR/program.c" -o $TMPDIR/a.out
60
61 perf record -o $TMPDIR/perf.data --branch-filter any,save_type,u -- $TMPDIR/a.out > /dev/null 2>&1
62 perf script -i $TMPDIR/perf.data --fields brstacksym | xargs -n1 > $TMPDIR/perf.script
63
64 # example of branch entries:
65 # foo+0x14/bar+0x40/P/-/-/0/CALL
66
67 set -x
68 egrep -m1 "^bench\+[^ ]*/foo\+[^ ]*/IND_CALL$" $TMPDIR/perf.script
69 egrep -m1 "^foo\+[^ ]*/bar\+[^ ]*/CALL$" $TMPDIR/perf.script
70 egrep -m1 "^bench\+[^ ]*/foo\+[^ ]*/CALL$" $TMPDIR/perf.script
71 egrep -m1 "^bench\+[^ ]*/bar\+[^ ]*/CALL$" $TMPDIR/perf.script
72 egrep -m1 "^bar\+[^ ]*/foo\+[^ ]*/RET$" $TMPDIR/perf.script
73 egrep -m1 "^foo\+[^ ]*/bench\+[^ ]*/RET$" $TMPDIR/perf.script
74 egrep -m1 "^bench\+[^ ]*/bench\+[^ ]*/COND$" $TMPDIR/perf.script
75 egrep -m1 "^main\+[^ ]*/main\+[^ ]*/UNCOND$" $TMPDIR/perf.script
76 set +x
77
78 # some branch types are still not being tested:
79 # IND COND_CALL COND_RET SYSCALL SYSRET IRQ SERROR NO_TX
80}
81
82# first argument <arg0> is the argument passed to "--branch-stack <arg0>,save_type,u"
83# second argument are the expected branch types for the given filter
84test_filter() {
85 local filter=$1
86 local expect=$2
87
88 echo "Testing branch stack filtering permutation ($filter,$expect)"
89
90 gen_test_program "$TEMPDIR/program.c"
91 cc -fno-inline -g "$TEMPDIR/program.c" -o $TMPDIR/a.out
92
93 perf record -o $TMPDIR/perf.data --branch-filter $filter,save_type,u -- $TMPDIR/a.out > /dev/null 2>&1
94 perf script -i $TMPDIR/perf.data --fields brstack | xargs -n1 > $TMPDIR/perf.script
95
96 # fail if we find any branch type that doesn't match any of the expected ones
97 # also consider UNKNOWN branch types (-)
98 if egrep -vm1 "^[^ ]*/($expect|-|( *))$" $TMPDIR/perf.script; then
99 return 1
100 fi
101}
102
103set -e
104
105test_user_branches
106
107test_filter "any_call" "CALL|IND_CALL|COND_CALL|SYSCALL|IRQ"
108test_filter "call" "CALL|SYSCALL"
109test_filter "cond" "COND"
110test_filter "any_ret" "RET|COND_RET|SYSRET|ERET"
111
112test_filter "call,cond" "CALL|SYSCALL|COND"
113test_filter "any_call,cond" "CALL|IND_CALL|COND_CALL|IRQ|SYSCALL|COND"
114test_filter "cond,any_call,any_ret" "COND|CALL|IND_CALL|COND_CALL|SYSCALL|IRQ|RET|COND_RET|SYSRET|ERET"