tests/tcg: add linux-user semihosting smoke test for ARM

We already use semihosting for the system stuff so this is a simple
smoke test to ensure we are working OK on linux-user.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20190913151845.12582-7-alex.bennee@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

tests/tcg/aarch64/Makefile.target

@@ -21,4 +21,9 @@ run-fcvt: fcvt
 AARCH64_TESTS += pauth-1 pauth-2
 run-pauth-%: QEMU_OPTS += -cpu max
 
+# Semihosting smoke test for linux-user
+AARCH64_TESTS += semihosting
+run-semihosting: semihosting
+	$(call run-test,$<,$(QEMU) $< 2> $<.err, "$< on $(TARGET_NAME)")
+
 TESTS += $(AARCH64_TESTS)

tests/tcg/arm/Makefile.target

@@ -27,6 +27,11 @@ run-fcvt: fcvt
 	$(call run-test,fcvt,$(QEMU) $<,"$< on $(TARGET_NAME)")
 	$(call diff-out,fcvt,$(ARM_SRC)/fcvt.ref)
 
+# Semihosting smoke test for linux-user
+ARM_TESTS += semihosting
+run-semihosting: semihosting
+	$(call run-test,$<,$(QEMU) $< 2> $<.err, "$< on $(TARGET_NAME)")
+
 TESTS += $(ARM_TESTS)
 
 # On ARM Linux only supports 4k pages

tests/tcg/arm/semihosting.c

@@ -0,0 +1,45 @@
+/*
+ * linux-user semihosting checks
+ *
+ * Copyright (c) 2019
+ * Written by Alex Bennée <alex.bennee@linaro.org>
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <stdint.h>
+
+#define SYS_WRITE0      0x04
+#define SYS_REPORTEXC   0x18
+
+void __semi_call(uintptr_t type, uintptr_t arg0)
+{
+#if defined(__arm__)
+    register uintptr_t t asm("r0") = type;
+    register uintptr_t a0 asm("r1") = arg0;
+    asm("svc 0xab"
+        : /* no return */
+        : "r" (t), "r" (a0));
+#else
+    register uintptr_t t asm("x0") = type;
+    register uintptr_t a0 asm("x1") = arg0;
+    asm("hlt 0xf000"
+        : /* no return */
+        : "r" (t), "r" (a0));
+#endif
+}
+
+int main(int argc, char *argv[argc])
+{
+#if defined(__arm__)
+    uintptr_t exit_code = 0x20026;
+#else
+    uintptr_t exit_block[2] = {0x20026, 0};
+    uintptr_t exit_code = (uintptr_t) &exit_block;
+#endif
+
+    __semi_call(SYS_WRITE0, (uintptr_t) "Hello World");
+    __semi_call(SYS_REPORTEXC, exit_code);
+    /* if we get here we failed */
+    return -1;
+}