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#!/bin/sh
# Check branch stack sampling
# SPDX-License-Identifier: GPL-2.0
# German Gomez <german.gomez@arm.com>, 2022
# we need a C compiler to build the test programs
# so bail if none is found
if ! [ -x "$(command -v cc)" ]; then
echo "failed: no compiler, install gcc"
exit 2
fi
# skip the test if the hardware doesn't support branch stack sampling
perf record -b -o- -B true > /dev/null 2>&1 || exit 2
TMPDIR=$(mktemp -d /tmp/__perf_test.program.XXXXX)
cleanup() {
rm -rf $TMPDIR
}
trap cleanup exit term int
gen_test_program() {
# generate test program
cat << EOF > $1
#define BENCH_RUNS 999999
int cnt;
void bar(void) {
} /* return */
void foo(void) {
bar(); /* call */
} /* return */
void bench(void) {
void (*foo_ind)(void) = foo;
if ((cnt++) % 3) /* branch (cond) */
foo(); /* call */
bar(); /* call */
foo_ind(); /* call (ind) */
}
int main(void)
{
int cnt = 0;
while (1) {
if ((cnt++) > BENCH_RUNS)
break;
bench(); /* call */
} /* branch (uncond) */
return 0;
}
EOF
}
test_user_branches() {
echo "Testing user branch stack sampling"
gen_test_program "$TEMPDIR/program.c"
cc -fno-inline -g "$TEMPDIR/program.c" -o $TMPDIR/a.out
perf record -o $TMPDIR/perf.data --branch-filter any,save_type,u -- $TMPDIR/a.out > /dev/null 2>&1
perf script -i $TMPDIR/perf.data --fields brstacksym | xargs -n1 > $TMPDIR/perf.script
# example of branch entries:
# foo+0x14/bar+0x40/P/-/-/0/CALL
set -x
egrep -m1 "^bench\+[^ ]*/foo\+[^ ]*/IND_CALL$" $TMPDIR/perf.script
egrep -m1 "^foo\+[^ ]*/bar\+[^ ]*/CALL$" $TMPDIR/perf.script
egrep -m1 "^bench\+[^ ]*/foo\+[^ ]*/CALL$" $TMPDIR/perf.script
egrep -m1 "^bench\+[^ ]*/bar\+[^ ]*/CALL$" $TMPDIR/perf.script
egrep -m1 "^bar\+[^ ]*/foo\+[^ ]*/RET$" $TMPDIR/perf.script
egrep -m1 "^foo\+[^ ]*/bench\+[^ ]*/RET$" $TMPDIR/perf.script
egrep -m1 "^bench\+[^ ]*/bench\+[^ ]*/COND$" $TMPDIR/perf.script
egrep -m1 "^main\+[^ ]*/main\+[^ ]*/UNCOND$" $TMPDIR/perf.script
set +x
# some branch types are still not being tested:
# IND COND_CALL COND_RET SYSCALL SYSRET IRQ SERROR NO_TX
}
# first argument <arg0> is the argument passed to "--branch-stack <arg0>,save_type,u"
# second argument are the expected branch types for the given filter
test_filter() {
local filter=$1
local expect=$2
echo "Testing branch stack filtering permutation ($filter,$expect)"
gen_test_program "$TEMPDIR/program.c"
cc -fno-inline -g "$TEMPDIR/program.c" -o $TMPDIR/a.out
perf record -o $TMPDIR/perf.data --branch-filter $filter,save_type,u -- $TMPDIR/a.out > /dev/null 2>&1
perf script -i $TMPDIR/perf.data --fields brstack | xargs -n1 > $TMPDIR/perf.script
# fail if we find any branch type that doesn't match any of the expected ones
# also consider UNKNOWN branch types (-)
if egrep -vm1 "^[^ ]*/($expect|-|( *))$" $TMPDIR/perf.script; then
return 1
fi
}
set -e
test_user_branches
test_filter "any_call" "CALL|IND_CALL|COND_CALL|SYSCALL|IRQ"
test_filter "call" "CALL|SYSCALL"
test_filter "cond" "COND"
test_filter "any_ret" "RET|COND_RET|SYSRET|ERET"
test_filter "call,cond" "CALL|SYSCALL|COND"
test_filter "any_call,cond" "CALL|IND_CALL|COND_CALL|IRQ|SYSCALL|COND"
test_filter "cond,any_call,any_ret" "COND|CALL|IND_CALL|COND_CALL|SYSCALL|IRQ|RET|COND_RET|SYSRET|ERET"
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