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# SPDX-License-Identifier: GPL-2.0
# Common helpers for CoreSight exception entry and return tests.
cleanup()
{
rm -rf "$tmpdir"
}
record_trace_with_cpu_clock()
{
local cf="$tmpdir/ctl"
local af="$tmpdir/ack"
local clock_opts=()
record_freq=$1
shift
# A zero frequency omits the cpu-clock event.
if [ "$record_freq" -gt 0 ]; then
# Generate timer IRQs without delivering a signal to the workload.
clock_opts=(-e cpu-clock:u -F "$record_freq")
fi
# FIFO control bounds the trace to the workload.
# --kcore supplies the running kernel's instructions for decoding.
taskset -c "$cpu" perf record -B --no-bpf-event --per-thread --kcore \
-e cs_etm/timestamp=0/uk "${clock_opts[@]}" \
-m,4M -D -1 --control "fifo:$cf,$af" \
-o "$tmpdir/data" -- \
perf test --record-ctl "fifo:$cf,$af" -w "$@" \
> "$tmpdir/record.log" 2>&1
}
record_trace()
{
record_trace_with_cpu_clock 0 "$@"
}
decode_trace()
{
local sw_fields=()
# perf script rejects -F sw: when no software event was recorded.
if [ "$record_freq" -gt 0 ]; then
sw_fields=(-F sw:)
fi
if ! perf script -i "$tmpdir/data" --itrace=b \
-F hw:ip,addr,flags,insn "${sw_fields[@]}" \
> "$tmpdir/script" 2> "$tmpdir/script.log"; then
cat "$tmpdir/script.log"
echo "Failed to decode the exception trace"
return 1
fi
}
# Arguments: entry pattern, exit pattern, expected return PC - entry PC.
# Return 2 if no complete pair survives the trace gaps.
check_exception_pairs()
{
local difference=$3 entry_pc resume_pc pairs=0
awk -v entry_pattern="$1" -v exit_pattern="$2" '
function address(pc) {
sub(/^0[xX]/, "", pc)
sub(/^0+/, "", pc)
return "0x" (pc == "" ? "0" : tolower(pc))
}
BEGIN {
entry_pattern = "^[[:space:]]*(" entry_pattern ")([[:space:]]|$)"
exit_pattern = "^[[:space:]]*(" exit_pattern ")([[:space:]]|$)"
}
NF {
# A trace boundary invalidates all pending entries, including nested ones.
if ($1 == "tr" && ($2 == "strt" || $2 == "end")) {
depth = 0
next
}
is_entry = ($1 == "hw" && $2 == "int") || $1 == "int" || $1 == "syscall"
is_exit = $1 == "iret" || $1 == "sysret"
if (!is_entry && !is_exit)
next
# Branch fields are: flags source => destination [insn: bytes].
arrow = 0
for (i = 1; i <= NF; i++) {
if ($i == "=>") {
arrow = i
break
}
}
if (arrow < 3 || arrow == NF) {
print "FAIL: Unexpected perf script output: " $0 > "/dev/stderr"
errors++
depth = 0
next
}
# Track every exception so an unrelated nested IRET cannot close
# a selected outer entry. Match the requested flags at each depth.
if (is_entry) {
entry_pc[++depth] = address($(arrow - 1))
selected[depth] = $0 ~ entry_pattern
next
}
if (!depth)
next
if (selected[depth] && $0 ~ exit_pattern)
print entry_pc[depth], address($(arrow + 1))
depth--
}
END {
if (errors)
exit 1
}' "$tmpdir/script" > "$tmpdir/exception_pairs" || return 1
# Bash uses integer arithmetic, preserving all bits of 64-bit PCs.
while read -r entry_pc resume_pc; do
if [ "$((resume_pc - entry_pc))" -ne "$difference" ]; then
printf "FAIL: Entry %s returns to %s, expected PC difference %d\n" \
"$entry_pc" "$resume_pc" "$difference"
return 1
fi
pairs=$((pairs + 1))
done < "$tmpdir/exception_pairs"
if [ "$pairs" -eq 0 ]; then
echo "No complete exception entry/exit pair"
return 2
fi
printf "Checked %d exception pairs with PC difference %d\n" "$pairs" "$difference"
}
setup_exception_test()
{
[ "$(uname -m)" = aarch64 ] || return 2
perf check feature -q libopencsd || return 2
[ -d /sys/bus/event_source/devices/cs_etm ] || return 2
export LC_ALL=C
command -v taskset >/dev/null 2>&1 || return 2
tmpdir=$(mktemp -d /tmp/perf-cs-etm-exception.XXXXXX) || return 1
trap cleanup EXIT
trap 'exit 1' HUP INT TERM
mkfifo "$tmpdir/ctl" "$tmpdir/ack" || return 1
# Keep each exception entry and return in the same trace queue.
cpu=$(awk '/Cpus_allowed_list:/ {
split($2, cpus, /[-,]/)
print cpus[1]
}' /proc/self/status)
# Check permissions, FIFO control and the trace sink before testing.
if ! record_trace callchain; then
cat "$tmpdir/record.log"
echo "[Skip] Cannot record user/kernel CoreSight trace with --kcore"
return 2
fi
return 0
}
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