tests/tcg/aarch64: Add MTE gdbstub tests

Add tests to exercise the MTE stubs. The tests will only run if a
version of GDB that supports MTE is available in the test environment.

Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
[AJB: re-base and checkpatch fixes]
Message-Id: <20240628050850.536447-12-gustavo.romero@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240705084047.857176-41-alex.bennee@linaro.org>

configure

@@ -1673,6 +1673,10 @@ for target in $target_list; do
           echo "GDB=$gdb_bin" >> $config_target_mak
       fi
 
+      if test "${arch}" = "aarch64" && version_ge ${gdb_version##* } 15.0; then
+          echo "GDB_HAS_MTE=y" >> $config_target_mak
+      fi
+
       echo "run-tcg-tests-$target: $qemu\$(EXESUF)" >> Makefile.prereqs
       tcg_tests_targets="$tcg_tests_targets $target"
   fi

tests/tcg/aarch64/Makefile.target

@@ -64,7 +64,7 @@ AARCH64_TESTS += bti-2
 
 # MTE Tests
 ifneq ($(CROSS_CC_HAS_ARMV8_MTE),)
-AARCH64_TESTS += mte-1 mte-2 mte-3 mte-4 mte-5 mte-6 mte-7
+AARCH64_TESTS += mte-1 mte-2 mte-3 mte-4 mte-5 mte-6 mte-7 mte-8
 mte-%: CFLAGS += $(CROSS_CC_HAS_ARMV8_MTE)
 endif
 
@@ -131,6 +131,18 @@ run-gdbstub-sve-ioctls: sve-ioctls
 	basic gdbstub SVE ZLEN support)
 
 EXTRA_RUNS += run-gdbstub-sysregs run-gdbstub-sve-ioctls
+
+ifeq ($(GDB_HAS_MTE),y)
+run-gdbstub-mte: mte-8
+	$(call run-test, $@, $(GDB_SCRIPT) \
+		--gdb $(GDB) \
+		--qemu $(QEMU) --qargs "$(QEMU_OPTS)" \
+		--bin $< --test $(AARCH64_SRC)/gdbstub/test-mte.py, \
+	gdbstub MTE support)
+
+EXTRA_RUNS += run-gdbstub-mte
+endif
+
 endif
 endif
 

tests/tcg/aarch64/gdbstub/test-mte.py

@@ -0,0 +1,86 @@
+from __future__ import print_function
+#
+# Test GDB memory-tag commands that exercise the stubs for the qIsAddressTagged,
+# qMemTag, and QMemTag packets. Logical tag-only commands rely on local
+# operations, hence don't exercise any stub.
+#
+# The test consists in breaking just after a atag() call (which sets the
+# allocation tag -- see mte-8.c for details) and setting/getting tags in
+# different memory locations and ranges starting at the address of the array
+# 'a'.
+#
+# This is launched via tests/guest-debug/run-test.py
+#
+
+
+import gdb
+import re
+from test_gdbstub import main, report
+
+
+PATTERN_0 = "Memory tags for address 0x[0-9a-f]+ match \(0x[0-9a-f]+\)."
+PATTERN_1 = ".*(0x[0-9a-f]+)"
+
+
+def run_test():
+    gdb.execute("break 95", False, True)
+    gdb.execute("continue", False, True)
+    try:
+        # Test if we can check correctly that the allocation tag for
+        # array 'a' matches the logical tag after atag() is called.
+        co = gdb.execute("memory-tag check a", False, True)
+        tags_match = re.findall(PATTERN_0, co, re.MULTILINE)
+        if tags_match:
+            report(True, f"{tags_match[0]}")
+        else:
+            report(False, "Logical and allocation tags don't match!")
+
+        # Test allocation tag 'set and print' commands. Commands on logical
+        # tags rely on local operation and so don't exercise any stub.
+
+        # Set the allocation tag for the first granule (16 bytes) of
+        # address starting at 'a' address to a known value, i.e. 0x04.
+        gdb.execute("memory-tag set-allocation-tag a 1 04", False, True)
+
+        # Then set the allocation tag for the second granule to a known
+        # value, i.e. 0x06. This tests that contiguous tag granules are
+        # set correct and don't run over each other.
+        gdb.execute("memory-tag set-allocation-tag a+16 1 06", False, True)
+
+        # Read the known values back and check if they remain the same.
+
+        co = gdb.execute("memory-tag print-allocation-tag a", False, True)
+        first_tag = re.match(PATTERN_1, co)[1]
+
+        co = gdb.execute("memory-tag print-allocation-tag a+16", False, True)
+        second_tag = re.match(PATTERN_1, co)[1]
+
+        if first_tag == "0x4" and second_tag == "0x6":
+            report(True, "Allocation tags are correctly set/printed.")
+        else:
+            report(False, "Can't set/print allocation tags!")
+
+        # Now test fill pattern by setting a whole page with a pattern.
+        gdb.execute("memory-tag set-allocation-tag a 4096 0a0b", False, True)
+
+        # And read back the tags of the last two granules in page so
+        # we also test if the pattern is set correctly up to the end of
+        # the page.
+        co = gdb.execute("memory-tag print-allocation-tag a+4096-32", False, True)
+        tag = re.match(PATTERN_1, co)[1]
+
+        co = gdb.execute("memory-tag print-allocation-tag a+4096-16", False, True)
+        last_tag = re.match(PATTERN_1, co)[1]
+
+        if tag == "0xa" and last_tag == "0xb":
+            report(True, "Fill pattern is ok.")
+        else:
+            report(False, "Fill pattern failed!")
+
+    except gdb.error:
+        # This usually happens because a GDB version that does not
+        # support memory tagging was used to run the test.
+        report(False, "'memory-tag' command failed!")
+
+
+main(run_test, expected_arch="aarch64")

tests/tcg/aarch64/mte-8.c

@@ -0,0 +1,99 @@
+/*
+ * To be compiled with -march=armv8.5-a+memtag
+ *
+ * This test is adapted from a Linux test. Please see:
+ *
+ * https://www.kernel.org/doc/html/next/arch/arm64/memory-tagging-extension.html#example-of-correct-usage
+ */
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/auxv.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <string.h>
+/*
+ * From arch/arm64/include/uapi/asm/hwcap.h
+ */
+#define HWCAP2_MTE              (1 << 18)
+
+/*
+ * From arch/arm64/include/uapi/asm/mman.h
+ */
+#define PROT_MTE                 0x20
+
+/*
+ * Insert a random logical tag into the given pointer.
+ */
+#define insert_random_tag(ptr) ({                   \
+    uint64_t __val;                                 \
+    asm("irg %0, %1" : "=r" (__val) : "r" (ptr));   \
+    __val;                                          \
+})
+
+/*
+ * Set the allocation tag on the destination address.
+ */
+#define set_tag(tagged_addr) do {                                      \
+        asm volatile("stg %0, [%0]" : : "r" (tagged_addr) : "memory"); \
+} while (0)
+
+
+int main(int argc, char *argv[])
+{
+    unsigned char *a;
+    unsigned long page_sz = sysconf(_SC_PAGESIZE);
+    unsigned long hwcap2 = getauxval(AT_HWCAP2);
+
+    /* check if MTE is present */
+    if (!(hwcap2 & HWCAP2_MTE)) {
+        return EXIT_FAILURE;
+    }
+
+    /*
+     * Enable the tagged address ABI, synchronous or asynchronous MTE
+     * tag check faults (based on per-CPU preference) and allow all
+     * non-zero tags in the randomly generated set.
+     */
+    if (prctl(PR_SET_TAGGED_ADDR_CTRL,
+              PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC | PR_MTE_TCF_ASYNC |
+              (0xfffe << PR_MTE_TAG_SHIFT),
+              0, 0, 0)) {
+        perror("prctl() failed");
+        return EXIT_FAILURE;
+    }
+
+    a = mmap(0, page_sz, PROT_READ | PROT_WRITE,
+             MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    if (a == MAP_FAILED) {
+        perror("mmap() failed");
+        return EXIT_FAILURE;
+    }
+
+    printf("a[] address is %p\n", a);
+
+    /*
+     * Enable MTE on the above anonymous mmap. The flag could be passed
+     * directly to mmap() and skip this step.
+     */
+    if (mprotect(a, page_sz, PROT_READ | PROT_WRITE | PROT_MTE)) {
+        perror("mprotect() failed");
+        return EXIT_FAILURE;
+    }
+
+    /* access with the default tag (0) */
+    a[0] = 1;
+    a[1] = 2;
+
+    printf("a[0] = %hhu a[1] = %hhu\n", a[0], a[1]);
+
+    /* set the logical and allocation tags */
+    a = (unsigned char *)insert_random_tag(a);
+    set_tag(a);
+
+    printf("%p\n", a);
+
+    return 0;
+}