1 files changed, 50 insertions, 0 deletions
diff --git a/tools/guest-diag/sem_slots.py b/tools/guest-diag/sem_slots.py
new file mode 100755
index 0000000..70d184c
--- /dev/null
+++ b/tools/guest-diag/sem_slots.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+# sem_slots.py - read or write the per-channel u32 completion counters of a
+# guest process (verification and fallback for the host's counter publish).
+#
+# Usage:
+#   sudo python3 sem_slots.py <pid> <first-va> [count]              # read
+#   sudo python3 sem_slots.py <pid> <first-va> [count] --write <v>  # write
+#
+# The slots are 16 bytes apart (one u32 per channel). Reading needs pagemap/
+# mem access as root; writing uses /proc/<pid>/mem and mirrors the gdb poke
+# used in earlier sessions (e.g. --write 1 to arm every waiter).
+import os
+import sys
+
+
+def main():
+    if len(sys.argv) < 3:
+        print(__doc__)
+        return 1
+    pid = int(sys.argv[1])
+    first = int(sys.argv[2], 16)
+    count = 20
+    write_val = None
+    i = 3
+    while i < len(sys.argv):
+        if sys.argv[i] == '--write':
+            write_val = int(sys.argv[i + 1], 0)
+            i += 2
+            continue
+        count = int(sys.argv[i], 0)
+        i += 1
+
+    flags = os.O_RDWR if write_val is not None else os.O_RDONLY
+    mem = os.open('/proc/%d/mem' % pid, flags)
+    try:
+        for n in range(count):
+            va = first + n * 16
+            if write_val is not None:
+                os.pwrite(mem, write_val.to_bytes(4, 'little'), va)
+                print('idx=%d VA=0x%x written=%u' % (n, va, write_val))
+            else:
+                v = int.from_bytes(os.pread(mem, 4, va), 'little')
+                print('idx=%d VA=0x%x val=%u' % (n, va, v))
+    finally:
+        os.close(mem)
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())