From b19c83e9724c94f412d448575b9fcdf193ac1315 Mon Sep 17 00:00:00 2001
From: Arthur Hanson Rasmusson <arthur@vgpu.io>
Date: Wed, 30 Sep 2026 03:20:38 -0400
Subject: guest-diag: bpz19 - attach-mode path trace through FUN_0042aec0

---
 tools/guest-diag/bpz19.py            | 77 ++++++++++++++++++++++++++++++++++++
 tools/guest-diag/push_guest_tools.sh |  1 +
 2 files changed, 78 insertions(+)
 create mode 100644 tools/guest-diag/bpz19.py

(limited to 'tools')

diff --git a/tools/guest-diag/bpz19.py b/tools/guest-diag/bpz19.py
new file mode 100644
index 0000000..9dfed68
--- /dev/null
+++ b/tools/guest-diag/bpz19.py
@@ -0,0 +1,77 @@
+# gdb script: trace the path through FUN_0042aec0 (GPU arch/config init) by
+# attaching to a running cdt at the CDT_PAUSE (bpz18 variant).
+#
+# Host: c48=6 c4c=0x27 c50=7 c54=5 e94=0x18. Guest reaches same c48..c54 but
+# e94=0, so some branch inside FUN_0042aec0 diverges. This logs hits on:
+#   0x32aec0 FUN_0042aec0 entry
+#   0x32b0b7 after chip-info store
+#   0x32c911 the 0xc4c dispatch
+#   0x32e8be case index 1 body (sets e94=0x18)
+#   0x32e46a default target of the dispatch
+#   0x2e3e80 FUN_003e3e80 (terminator; dumps ds fields)
+import gdb
+import time
+
+gdb.execute("set pagination off")
+gdb.execute("set confirm off")
+out = gdb.execute("info proc mappings", to_string=True)
+base = None
+for line in out.splitlines():
+    if "libcuda" in line and "r-xp" in line:
+        f = line.split()
+        base = int(f[0], 16) - int(f[3], 16)
+        break
+print("BASE=0x%x" % (base or 0))
+if base is None:
+    raise SystemExit
+
+SITES = [
+    (0x32aec0, "F42AEC0_ENTRY"),
+    (0x32b0b7, "AFTER_CHIPINFO"),
+    (0x32c911, "C4C_DISPATCH"),
+    (0x32e8be, "CASE1_e94_0x18"),
+    (0x32e46a, "DISPATCH_DEFAULT"),
+]
+for off, name in SITES:
+    gdb.execute("break *0x%x" % (base + off))
+CALLER_RET = base + 0xd0eae1
+gdb.execute("break *0x%x" % (base + 0x2e3e80))
+
+def rd(addr, n=4, fmt="unsigned int"):
+    try:
+        return int(gdb.parse_and_eval("*(%s*)0x%x" % (fmt, addr))) & ((1 << (8 * n)) - 1)
+    except Exception:
+        return None
+
+t0 = time.time()
+for hit in range(120):
+    try:
+        gdb.execute("continue")
+    except gdb.error as e:
+        print("CONTINUE_END %s" % e)
+        break
+    rip = int(gdb.parse_and_eval("$rip")) & 0xffffffffffffffff
+    off = rip - base
+    if off == 0x2e3e80:
+        ret = rd(int(gdb.parse_and_eval("$rsp")), 8, "unsigned long")
+        if ret != CALLER_RET:
+            continue
+        rdi = int(gdb.parse_and_eval("$rdi")) & 0xffffffffffffffff
+        ds = rd(rdi + 0x40, 8, "unsigned long")
+        print("TERMINATOR FUN_003e3e80 dev=0x%x ds=0x%x t=%.3f" % (rdi, ds or 0, time.time() - t0))
+        for o in [0xc48, 0xc4c, 0xc50, 0xc54, 0xe94, 0x4354, 0x426c]:
+            print("  ds+0x%x = 0x%x" % (o, rd(ds + o) or 0))
+        break
+    name = dict((o, n) for o, n in SITES).get(off, "?")
+    rcx = int(gdb.parse_and_eval("$rcx")) & 0xffffffffffffffff
+    eax = rd("$eax") if False else (int(gdb.parse_and_eval("$eax")) & 0xffffffff)
+    extra = ""
+    if off == 0x32c911:
+        extra = " c4c=0x%x arch=0x%x" % (rd(rcx + 0xc4c) or 0, rd(rcx + 0xc50) or 0)
+    print("HIT t=%.3f +0x%x %s eax=0x%x rcx=0x%x%s" %
+          (time.time() - t0, off, name, eax, rcx, extra))
+
+try:
+    gdb.execute("detach")
+except Exception:
+    pass
diff --git a/tools/guest-diag/push_guest_tools.sh b/tools/guest-diag/push_guest_tools.sh
index ffb9b29..873a7fc 100755
--- a/tools/guest-diag/push_guest_tools.sh
+++ b/tools/guest-diag/push_guest_tools.sh
@@ -43,6 +43,7 @@ push_b64 "$HERE/bpz12.py"      /tmp/bpz12.py
 push_b64 "$HERE/bpz13.py"      /tmp/bpz13.py
 push_b64 "$HERE/bpz14.py"      /tmp/bpz14.py
 push_b64 "$HERE/bpz16.py"      /tmp/bpz16.py
+push_b64 "$HERE/bpz19.py"      /tmp/bpz19.py
 push_b64 "$HERE/invd.py"        /tmp/invd.py
 push_b64 "$HERE/bpwait.py"      /tmp/bpwait.py
 push_b64 "$HERE/ctx999.py"      /tmp/ctx999.py
-- 
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