"exception raised while parsing perf output" with "cbr: 36 freq: 3629 MHz (450%)"

[ednolan]

With Ubuntu 24.04, magic-trace 1.2.4 fails to parse the perf data it records for a simple test application when -trace-include-kernel is specified:

root@eddie-beman-server:~# /home/eddie/magic-trace --version
v1.2.4
root@eddie-beman-server:~# perf --version
perf version 6.8.12
root@eddie-beman-server:~# head -n 1 /etc/os-release
PRETTY_NAME="Ubuntu 24.04.1 LTS"
root@eddie-beman-server:~# head -n 5 /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 190
model name      : Intel(R) N150
root@eddie-beman-server:~# echo 'int main() { for (int i = 0; i < 1000000000; ++i) {} }' > foo.c && gcc -O0 ./foo.c -o foo
root@eddie-beman-server:~# MAGIC_TRACE_DEBUG=1 /home/eddie/magic-trace run -z-print-perf-commands -trace-include-kernel ./foo
perf record -o /tmp/magic_trace.tmp.27fbc1/perf.data --timestamp --event=intel_pt/cyc=1,cyc_thresh=1,mtc_period=0/uk --per-thread -t 377433 --snapshot=e --kcore
[ Snapshot taken. ]
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 4.015 MB /tmp/magic_trace.tmp.27fbc1/perf.data ]
[ Finished recording. ]
[ Decoding, this takes a while... ]
perf script -i /tmp/magic_trace.tmp.27fbc1/perf.data --ns --itrace=bep -F pid,tid,time,flags,ip,addr,sym,symoff,synth,dso,event,period --dlfilter /tmp/magic_trace.tmp.27fbc1/perf_dlfilter.so
(monitor.ml.Error
 ("BUG: exception raised while parsing perf output. Please report this to https://github.com/janestreet/magic-trace/issues/"
  (exn Not_found)
  (perf_output
   (" 377433/377433  1693789.232275122:          1                                         cbr:   D                      cbr: 36 freq: 3629 MHz (450%)                   0     6143f240a145 main+0x1c (/root/foo)")))
 ("Raised at Base__Error.raise in file \"src/error.ml\" (inlined), line 9, characters 14-30"
  "Called from Base__Error.raise_s in file \"src/error.ml\", line 10, characters 19-40"
  "Called from Async_kernel__Pipe.map.(fun) in file \"src/pipe.ml\", line 1066, characters 65-70"
  "Called from Async_kernel__Job_queue.run_jobs in file \"src/job_queue.ml\", line 180, characters 6-47"
  "Caught by monitor Monitor.protect"))