From 45978e9202412fb9fc6088718e9720f22ece7b30 Mon Sep 17 00:00:00 2001
From: Arthur Hanson Rasmusson <arthur@vgpu.io>
Date: Sun, 25 Oct 2026 05:21:29 -0400
Subject: wall-2 forensics tools: GR channel-init push localization (session
 73)

Tools and findings from the live wall-2 campaign (r674/r675): the vk_frame
client's GR channel-init push (va=0x4480000 len=1432) cannot be translated by
the sema service, so no release is applied and vkCreateDevice fails -4.

Captured: the RM window-record/memdesc layout (ring memdesc PA == the
service's validated ring pa; push memdesc PA injected live and read by the
service without a false-translation line), the CE-only shape of the service
rescue matcher, the notrace status of nvidia/modeset kprobes (QEMU gdb hbreak
works), and the ring-entry encoding from channelFillGpFifo/nvWriteGpEntry
(neither runs for this channel's kick).

New tools: wall2_resolver{2..5}.py, wall2_livecap{1..3}.py, RAM structure
scanners (scan_r673*.py, trace_push674.py), gdb675*.gdb probes, plus a
README with the ranked next steps.
---
 tools/guest-diag/wall2/wall2_resolver3.py | 136 ++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 tools/guest-diag/wall2/wall2_resolver3.py

(limited to 'tools/guest-diag/wall2/wall2_resolver3.py')

diff --git a/tools/guest-diag/wall2/wall2_resolver3.py b/tools/guest-diag/wall2/wall2_resolver3.py
new file mode 100644
index 0000000..4b16686
--- /dev/null
+++ b/tools/guest-diag/wall2/wall2_resolver3.py
@@ -0,0 +1,136 @@
+#!/usr/bin/env python3
+# wall2_resolver3.py - HOST-SIDE wall#2 resolver v3: the RM window-memdesc recipe.
+#
+# Proven structure (r674/r675): the RM keeps per-window records
+#   {..., VA, SIZE, ...}  (head/tail list nodes)
+# and per-window memdescs in the same page:
+#   {SIZE, 0x03008000, FIRST_PA, ptr}
+# where FIRST_PA is the PA of the window's FIRST VA page. Verified: the ring
+# window {VA=0x44a0000, SIZE=0x40000} -> memdesc PA == the service's validated
+# ring pa (0x1158ce000 r675). Therefore the push window
+# {VA=0x4480000, SIZE=0x20000} -> memdesc PA == PA of VA 0x4480000 (the push
+# page the sema service cannot translate).
+#
+# Recipe: wait for the ring line -> find the ring window memdesc
+# {0x40000, 0x03008000, RING_PA} -> in the same page find the push window
+# memdesc {0x20000, 0x03008000, PUSH_PA} -> inject 0x4480000 -> PUSH_PA.
+import subprocess, struct, time, sys, re, os
+
+RAM = "/dev/shm/vgpu-guest-ram"
+PARAM = "/sys/module/vgsp/parameters/sema_map_add"
+LOG = "/tmp/opencode/wall2_resolver3.log"
+PUSH_VA = 0x4480000
+WAIT_RING_S = int(os.environ.get("W2_WAIT_RING", "420"))
+WATCH_S = int(os.environ.get("W2_WATCH", "150"))
+
+logf = open(LOG, "a", buffering=1)
+def log(*a):
+    s = " ".join(str(x) for x in a)
+    print(s, flush=True)
+    logf.write("[%s] %s\n" % (time.strftime("%H:%M:%S"), s))
+
+img = open(RAM, "rb", buffering=0)
+def gpa2off(pa):
+    if pa < 0x80000000: return pa
+    if pa < 0x180000000: return 0x80000000 + (pa - 0x100000000)
+    return None
+def off2gpa(off):
+    return off if off < 0x80000000 else 0x100000000 + (off - 0x80000000)
+def rd(pa, n):
+    off = gpa2off(pa)
+    if off is None: return None
+    img.seek(off); return img.read(n)
+
+def dmesg():
+    return subprocess.run(["sudo", "dmesg"], capture_output=True, text=True).stdout
+
+def inject(va, pa, ln=0x1000, ap=1):
+    try:
+        with open(PARAM, "w") as f:
+            f.write("0x%x,0x%x,0x%x,%d\n" % (va, pa, ln, ap))
+        log("INJECT va=0x%x -> pa=0x%x len=0x%x" % (va, pa, ln))
+        return True
+    except OSError as e:
+        log("inject FAIL", e)
+        return False
+
+def find_memdescs(size):
+    """Find {size, 0x03008000, PA} patterns; returns [(page, off, pa)]."""
+    img.seek(0, 2); fsz = img.tell()
+    pat = struct.pack("<QQ", size, 0x03008000)
+    out = []
+    CH = 64 << 20
+    pos = 0
+    while pos < fsz:
+        img.seek(pos); d = img.read(min(CH, fsz - pos))
+        st = 0
+        while True:
+            i = d.find(pat, st)
+            if i < 0: break
+            st = i + 1
+            if i + 24 > len(d): continue
+            pa = struct.unpack_from("<Q", d, i + 16)[0]
+            gpa = off2gpa(pos + i)
+            if 0x100000000 <= pa < 0x180000000:
+                out.append((gpa & ~0xfff, gpa - (gpa & ~0xfff), pa))
+        pos += CH
+    return out
+
+def main():
+    log("=== resolver3 start ===")
+    # count pre-existing ring lines; wait for a NEW one (fresh client kick)
+    def ring_lines():
+        out = []
+        for ln in dmesg().splitlines():
+            m = re.search(r"ring rc=0 pa=0x([0-9a-f]+) ap=", ln)
+            if m:
+                out.append(int(m.group(1), 16))
+        return out
+    base = ring_lines()
+    log("pre-existing ring lines: %d" % len(base))
+    ring_pa = None
+    deadline = time.time() + WAIT_RING_S
+    while time.time() < deadline:
+        cur = ring_lines()
+        if len(cur) > len(base):
+            ring_pa = cur[-1]
+            break
+        time.sleep(1)
+    if not ring_pa:
+        log("no NEW ring line; exit"); return 1
+    log("NEW RING PA = 0x%x" % ring_pa)
+
+    injected = set()
+    watch = time.time() + WATCH_S
+    while time.time() < watch:
+        # ring window memdesc {0x40000, 0x03008000, ring_pa}
+        rd_hits = [x for x in find_memdescs(0x40000) if x[2] == ring_pa]
+        if not rd_hits:
+            time.sleep(0.5); continue
+        for (page, off, _pa) in rd_hits:
+            d = rd(page, 0x1000)
+            if not d: continue
+            # find sibling push memdesc in the same page
+            for o in range(0, 0x1000 - 24, 8):
+                sz, fl = struct.unpack_from("<QQ", d, o)
+                if sz == 0x20000 and fl == 0x03008000:
+                    pa = struct.unpack_from("<Q", d, o + 16)[0]
+                    if not (0x100000000 <= pa < 0x180000000):
+                        continue
+                    key = (page, pa)
+                    if key in injected: continue
+                    log("memdesc page=0x%x ring_desc@0x%x push_desc@0x%x push_pa=0x%x"
+                        % (page, off, o, pa))
+                    # content sanity: read the push page
+                    pd = rd(pa, 0x40)
+                    log("   push page head: %s" % (pd.hex() if pd else "?"))
+                    if inject(PUSH_VA, pa, 0x1000):
+                        injected.add(key)
+        if injected and ("injected mapping va=0x%x" % PUSH_VA) in dmesg():
+            log("service confirmed; keep watching")
+        time.sleep(0.5)
+    log("=== resolver3 done: %d injection(s) ===" % len(injected))
+    return 0
+
+if __name__ == "__main__":
+    sys.exit(main())
-- 
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