a153c392f5
Executed the wait-object read on a live run under gdb. For every thread whose frame 3 is XObject::Wait, rbx gives a pointer whose first quadword is 0x5555562db8f0, which is the PIE base plus 0xd878f0, and the symbol table has vtable for xe::kernel::XEvent at 0xd878e0. The stored pointer is the vtable symbol plus sixteen, since offset-to-top and RTTI come first, so it matches exactly. The same vtable appears on every sampled waiting thread while the this pointers differ, meaning many threads waiting on different XEvent instances. The whole chain needs no DWARF and no rebuild, as the static groundwork predicted. Two caveats, both recorded rather than smoothed over. This is a healthy-play snapshot, not the freeze. The capture landed at 195 s of flight with screen_id reporting flight and a non-black mean, because boot under gdb costs about 300 s and the entire experiment has to fit inside one call -- a timeout kills the process group and takes the emulator with it, which lost an earlier attempt outright. So this describes what threads wait on during normal play, which is the control the frozen capture never had, but it is not the frozen case. And the this addresses look like host stack rather than heap. Either xenia places these objects somewhere unusual, or rbx at frame 3 is not Wait's this after the unwind and the vtable match is coincidence. An exact plus-sixteen match on a known symbol is hard to get by accident, but the address range is not what was expected. The settling check is to dump a few words at rbx and see whether they look like an XEvent -- vtable, KernelState pointer, handle and type fields -- or like saved registers.
64 lines
2.5 KiB
Bash
Executable File
64 lines
2.5 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Read WHICH object the frozen guest threads are waiting on.
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#
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# Groundwork (mission-freeze-resume-spin.md): XObject::Wait keeps `this` in %rbx,
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# and .eh_frame lets gdb restore callee-saved registers during the unwind, so no
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# DWARF and no rebuild are needed -- select the Wait frame, read rbx, then read
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# the vtable pointer at [rbx] and resolve it in the symtab.
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set -u
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export HOME=/sylph-home/re SDL_AUDIODRIVER=dummy DISPLAY=:98
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export PYTHONPATH=/sylph-home/.local/lib/python3.12/site-packages
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export XENIA_BIN=/sylph-home/re/bin/gdb-wrap/xenia_canary
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SD="$(cd "$(dirname "$0")" && pwd)"
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FLY="${1:-240}"
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CMD=/tmp/gdb-cmd; OUT=/tmp/gdb-out.log
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"$SD/launch_mission.sh" fly || { echo "BOOT FAILED"; exit 1; }
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CFG=/tmp/nav-fz.json
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for t in 1 2 3; do
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python3 "$SD/pad.py" set "rt=1" >/dev/null 2>&1 || true; sleep 3
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python3 "$SD/pad.py" clear >/dev/null 2>&1 || true
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if python3 "$SD/entities2.py" self 0x130 "$CFG" >/dev/null 2>&1; then
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SYLPH_HUNT=1 SYLPH_KEEPOUT=1400 nohup python3 "$SD/pilot.py" "$CFG" "$FLY" \
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</dev/null >/tmp/fz-pilot.log 2>&1 & P=$!; echo "--- pilot flying"; break
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fi
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done
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echo "--- flying ${FLY}s (boot under gdb costs ~300s, so this must leave room"
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echo "--- for the gdb step inside one call: timeout kills the whole group)"
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python3 -c "import time,sys; time.sleep(int(sys.argv[1]))" "$FLY"
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[ -n "${P:-}" ] && kill "$P" 2>/dev/null
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pid=$(pgrep -x gdb | head -1)
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[ -n "$pid" ] || { echo "no gdb"; exit 2; }
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before=$(wc -c < "$OUT")
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kill -INT "$pid"; sleep 3
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{
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echo 'echo === HOT THREAD WAIT OBJECTS ===\n'
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echo 'thread apply all bt 6'
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echo 'echo === END BT ===\n'
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} >> "$CMD"
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sleep 10
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tail -c +$((before + 1)) "$OUT" > /tmp/fz-bt.txt
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# find threads whose frame 3 is XObject::Wait, then read rbx there
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python3 - <<'PY' >> "$CMD"
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import re
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txt=open('/tmp/fz-bt.txt').read()
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cur=None
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for line in txt.splitlines():
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m=re.match(r'Thread (\d+) ', line)
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if m: cur=m.group(1)
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if cur and 'XObject::Wait' in line:
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print(r'echo === T%s ===\n' % cur)
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print('thread %s' % cur)
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print('frame 3')
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print('info registers rbx')
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print('x/1gx $rbx')
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cur=None
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print(r'echo === END OBJ ===\n')
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print('continue')
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PY
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sleep 12
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screenshot /tmp/fz-screen.png >/dev/null 2>&1
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echo "--- screen at capture time:"
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python3 "$SD/screen_id.py" /tmp/fz-screen.png 2>/dev/null | head -2
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tail -c +$((before + 1)) "$OUT" | sed -n '/HOT THREAD WAIT OBJECTS/,$p' | grep -vE "^\s*$" | tail -70
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echo "FREEZE WAITOBJ DONE"
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