[PATCH 2/2] tcg tests: add a test to verify the syscall filter plugin API

[Ziyang Zhang <functioner@sjtu.edu.cn>]

Register a syscall filter callback in tests/tcg/plugins/sycall.c,
returns a specific value for a magic system call number, and check
it in tests/tcg/multiarch/test-plugin-syscall-filter.c.

Signed-off-by: Ziyang Zhang <functioner@sjtu.edu.cn>
Co-authored-by: Mingyuan Xia <xiamy@ultrarisc.com>
---
 tests/tcg/multiarch/Makefile.target           |  4 +++-
 .../multiarch/test-plugin-syscall-filter.c    | 20 +++++++++++++++++++
 tests/tcg/plugins/syscall.c                   | 15 ++++++++++++++
 3 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 tests/tcg/multiarch/test-plugin-syscall-filter.c

diff --git a/tests/tcg/multiarch/Makefile.target b/tests/tcg/multiarch/Makefile.target
index f5b4d2b813..4005e3a8a9 100644
--- a/tests/tcg/multiarch/Makefile.target
+++ b/tests/tcg/multiarch/Makefile.target
@@ -202,8 +202,10 @@ run-plugin-test-plugin-mem-access-with-libmem.so: \
 	CHECK_PLUGIN_OUTPUT_COMMAND= \
 	$(SRC_PATH)/tests/tcg/multiarch/check-plugin-output.sh \
 	$(QEMU) $<
+run-plugin-test-plugin-syscall-filter-with-libsyscall.so:
 
-EXTRA_RUNS_WITH_PLUGIN += run-plugin-test-plugin-mem-access-with-libmem.so
+EXTRA_RUNS_WITH_PLUGIN += run-plugin-test-plugin-mem-access-with-libmem.so \
+			   			  run-plugin-test-plugin-syscall-filter-with-libsyscall.so
 endif
 
 # Update TESTS
diff --git a/tests/tcg/multiarch/test-plugin-syscall-filter.c b/tests/tcg/multiarch/test-plugin-syscall-filter.c
new file mode 100644
index 0000000000..cc694e0a71
--- /dev/null
+++ b/tests/tcg/multiarch/test-plugin-syscall-filter.c
@@ -0,0 +1,20 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This test attempts to execute a magic syscall. The syscall test plugin
+ * should intercept this and returns an expected value.
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[]) {
+    long ret = syscall(0x66CCFF);
+    if (ret != 0xFFCC66) {
+        perror("ERROR: syscall returned unexpected value!!!");
+        return EXIT_FAILURE;
+    }
+    return EXIT_SUCCESS;
+}
\ No newline at end of file
diff --git a/tests/tcg/plugins/syscall.c b/tests/tcg/plugins/syscall.c
index 42801f5c86..1323e18bc0 100644
--- a/tests/tcg/plugins/syscall.c
+++ b/tests/tcg/plugins/syscall.c
@@ -170,6 +170,20 @@ static void vcpu_syscall_ret(qemu_plugin_id_t id, unsigned int vcpu_idx,
     }
 }
 
+static bool vcpu_syscall_filter(qemu_plugin_id_t id, unsigned int vcpu_index,
+                                int64_t num, uint64_t a1, uint64_t a2,
+                                uint64_t a3, uint64_t a4, uint64_t a5,
+                                uint64_t a6, uint64_t a7, uint64_t a8,
+                                uint64_t *ret)
+{
+    if (num == 0x66CCFF) {
+        *ret = 0xFFCC66;
+        qemu_plugin_outs("syscall 0x66CCFF filtered, ret=0xFFCC66\n");
+        return true;
+    }
+    return false;
+}
+
 static void print_entry(gpointer val, gpointer user_data)
 {
     SyscallStats *entry = (SyscallStats *) val;
@@ -255,6 +269,7 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
 
     qemu_plugin_register_vcpu_syscall_cb(id, vcpu_syscall);
     qemu_plugin_register_vcpu_syscall_ret_cb(id, vcpu_syscall_ret);
+    qemu_plugin_register_vcpu_syscall_filter_cb(id, vcpu_syscall_filter);
     qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);
     return 0;
 }
-- 
2.34.1