tests/tcg: add a system test to check memory instrumentation

At first I thought I could compile the user-mode test for system mode
however we already have a fairly comprehensive test case for system
mode in "memory" so lets use that.

As tracking every access will quickly build up with "print-access" we
add a new mode to track groups of reads and writes to regions. Because
the test_data is 16k aligned we can be sure all accesses to it are
ones we can count.

First we extend the test to report where the test_data region is. Then
we expand the pdot() function to track the total number of reads and
writes to the region. We have to add some addition pdot() calls to
take into account multiple reads/writes in the test loops.

Finally we add a python script to integrate the data from the plugin
and the output of the test and validate they both agree on the total
counts. As some boot codes clear the bss we also add a flag to add a
regions worth of writes to the expected total.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-Id: <20240916085400.1046925-14-alex.bennee@linaro.org>

1 files changed, 130 insertions, 0 deletions

diff --git a/tests/tcg/multiarch/system/validate-memory-counts.py b/tests/tcg/multiarch/system/validate-memory-counts.py
new file mode 100755
index 0000000..5b8bbf3
--- /dev/null
+++ b/tests/tcg/multiarch/system/validate-memory-counts.py
@@ -0,0 +1,130 @@
+#!/usr/bin/env python3
+#
+# validate-memory-counts.py: check we instrumented memory properly
+#
+# This program takes two inputs:
+#   - the mem plugin output
+#   - the memory binary output
+#
+# Copyright (C) 2024 Linaro Ltd
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import sys
+from argparse import ArgumentParser
+
+def extract_counts(path):
+    """
+    Load the output from path and extract the lines containing:
+
+      Test data start: 0x40214000
+      Test data end: 0x40218001
+      Test data read: 2522280
+      Test data write: 262111
+
+    From the stream of data. Extract the values for use in the
+    validation function.
+    """
+    start_address = None
+    end_address = None
+    read_count = 0
+    write_count = 0
+    with open(path, 'r') as f:
+        for line in f:
+            if line.startswith("Test data start:"):
+                start_address = int(line.split(':')[1].strip(), 16)
+            elif line.startswith("Test data end:"):
+                end_address = int(line.split(':')[1].strip(), 16)
+            elif line.startswith("Test data read:"):
+                read_count = int(line.split(':')[1].strip())
+            elif line.startswith("Test data write:"):
+                write_count = int(line.split(':')[1].strip())
+    return start_address, end_address, read_count, write_count
+
+
+def parse_plugin_output(path, start, end):
+    """
+    Load the plugin output from path in the form of:
+
+      Region Base, Reads, Writes, Seen all
+      0x0000000040004000, 31093, 0, false
+      0x0000000040214000, 2522280, 278579, true
+      0x0000000040000000, 137398, 0, false
+      0x0000000040210000, 54727397, 33721956, false
+
+    And extract the ranges that match test data start and end and
+    return the results.
+    """
+    total_reads = 0
+    total_writes = 0
+    seen_all = False
+
+    with open(path, 'r') as f:
+        next(f)  # Skip the header
+        for line in f:
+
+            if line.startswith("Region Base"):
+                continue
+
+            parts = line.strip().split(', ')
+            if len(parts) != 4:
+                continue
+
+            region_base = int(parts[0], 16)
+            reads = int(parts[1])
+            writes = int(parts[2])
+
+            if start <= region_base < end: # Checking if within range
+                total_reads += reads
+                total_writes += writes
+                seen_all = parts[3] == "true"
+
+    return total_reads, total_writes, seen_all
+
+def main() -> None:
+    """
+    Process the arguments, injest the program and plugin out and
+    verify they match up and report if they do not.
+    """
+    parser = ArgumentParser(description="Validate memory instrumentation")
+    parser.add_argument('test_output',
+                        help="The output from the test itself")
+    parser.add_argument('plugin_output',
+                        help="The output from memory plugin")
+    parser.add_argument('--bss-cleared',
+                        action='store_true',
+                        help='Assume bss was cleared (and adjusts counts).')
+
+    args = parser.parse_args()
+
+    # Extract counts from memory binary
+    start, end, exp_reads, exp_writes = extract_counts(args.test_output)
+
+    # Some targets clear BSS before running but the test doesn't know
+    # that so we adjust it by the size of the test region.
+    if args.bss_cleared:
+        exp_writes += 16384
+
+    if start is None or end is None:
+        print("Failed to test_data boundaries from output.")
+        sys.exit(1)
+
+    # Parse plugin output
+    preads, pwrites, seen_all = parse_plugin_output(args.plugin_output,
+                                                    start, end)
+
+    if not seen_all:
+        print("Fail: didn't instrument all accesses to test_data.")
+        sys.exit(1)
+
+    # Compare and report
+    if preads == exp_reads and pwrites == exp_writes:
+        sys.exit(0)
+    else:
+        print("Fail: The memory reads and writes count does not match.")
+        print(f"Expected Reads: {exp_reads}, Actual Reads: {preads}")
+        print(f"Expected Writes: {exp_writes}, Actual Writes: {pwrites}")
+        sys.exit(1)
+
+if __name__ == "__main__":
+    main()