test: unit test for longjmp

Provide a unit test for the longjmp() library function

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: Sean Anderson <seanga2@gmail.com>

test/lib/Makefile

@@ -7,6 +7,7 @@ obj-$(CONFIG_EFI_LOADER) += efi_device_path.o
 obj-$(CONFIG_EFI_SECURE_BOOT) += efi_image_region.o
 obj-y += hexdump.o
 obj-y += lmb.o
+obj-y += longjmp.o
 obj-$(CONFIG_CONSOLE_RECORD) += test_print.o
 obj-$(CONFIG_SSCANF) += sscanf.o
 obj-y += string.o

test/lib/longjmp.c

@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Test setjmp(), longjmp()
+ *
+ * Copyright (c) 2021, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+
+#include <common.h>
+#include <test/lib.h>
+#include <test/test.h>
+#include <test/ut.h>
+#include <asm/setjmp.h>
+
+struct test_jmp_buf {
+	jmp_buf env;
+	int val;
+};
+
+/**
+ * test_longjmp() - test longjmp function
+ *
+ * @i is passed to longjmp.
+ * @i << 8 is set in the environment structure.
+ *
+ * @env:	environment
+ * @i:		value passed to longjmp()
+ */
+static noinline void test_longjmp(struct test_jmp_buf *env, int i)
+{
+	env->val = i << 8;
+	longjmp(env->env, i);
+}
+
+/**
+ * test_setjmp() - test setjmp function
+ *
+ * setjmp() will return the value @i passed to longjmp() if @i is non-zero.
+ * For @i == 0 we expect return value 1.
+ *
+ * @i << 8 will be set by test_longjmp in the environment structure.
+ * This value can be used to check that the stack frame is restored.
+ *
+ * We return the XORed values to allow simply check both at once.
+ *
+ * @i:		value passed to longjmp()
+ * Return:	values return by longjmp()
+ */
+static int test_setjmp(int i)
+{
+	struct test_jmp_buf env;
+	int ret;
+
+	env.val = -1;
+	ret = setjmp(env.env);
+	if (ret)
+		return ret ^ env.val;
+	test_longjmp(&env, i);
+	/* We should not arrive here */
+	return 0x1000;
+}
+
+static int lib_test_longjmp(struct unit_test_state *uts)
+{
+	int i;
+
+	for (i = -3; i < 0; ++i)
+		ut_asserteq(i ^ (i << 8), test_setjmp(i));
+	ut_asserteq(1, test_setjmp(0));
+	for (i = 1; i < 4; ++i)
+		ut_asserteq(i ^ (i << 8), test_setjmp(i));
+	return 0;
+}
+LIB_TEST(lib_test_longjmp, 0);