[PATCH 16/16 v3] function_graph: Add selftest for passing local variables

[Steven Rostedt]

From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>

Add boot up selftest that passes variables from a function entry to a
function exit, and make sure that they do get passed around. Also test
for some failure cases.

Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 kernel/trace/trace_selftest.c | 310 ++++++++++++++++++++++++++++++++++
 1 file changed, 310 insertions(+)

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index facd5d1c05e7..edee3c8bd307 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -718,6 +718,314 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define BYTE_NUMBER 123
+#define SHORT_NUMBER 12345
+#define WORD_NUMBER 1234567890
+#define LONG_NUMBER 1234567890123456789LL
+
+static int fgraph_store_size __initdata;
+static const char *fgraph_store_type_name __initdata;
+static char *fgraph_error_str __initdata;
+static char fgraph_error_str_buf[128] __initdata;
+
+static __init int store_entry(struct ftrace_graph_ent *trace,
+			      struct fgraph_ops *gops)
+{
+	const char *type = fgraph_store_type_name;
+	int size = fgraph_store_size;
+	void *p;
+	void *fail;
+
+	/* Try to reserve too much */
+	fail = fgraph_reserve_data(sizeof(long) * 4 + 1);
+	if (fail) {
+		snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+			 "Was able to reserve too much!\n");
+		fgraph_error_str = fgraph_error_str_buf;
+		return 0;
+	}
+	/* Reserve the amount we want to */
+	p = fgraph_reserve_data(size);
+	if (!p) {
+		snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+			 "Failed to reserve %s\n", type);
+		fgraph_error_str = fgraph_error_str_buf;
+		return 0;
+	}
+	/* We should only be able to reserve once */
+	fail = fgraph_reserve_data(4);
+	if (fail) {
+		snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+			 "Was able to reserve twice!\n");
+		fgraph_error_str = fgraph_error_str_buf;
+		return 0;
+	}
+
+	switch (fgraph_store_size) {
+	case 1:
+		*(char *)p = BYTE_NUMBER;
+		break;
+	case 2:
+		*(short *)p = SHORT_NUMBER;
+		break;
+	case 4:
+		*(int *)p = WORD_NUMBER;
+		break;
+	case 8:
+		*(long long *)p = LONG_NUMBER;
+		break;
+	case 12:
+		*(long long *)p = LONG_NUMBER;
+		p += 8;
+		*(int *)p = WORD_NUMBER;
+		break;
+	case 16:
+		*(long long *)p = LONG_NUMBER;
+		p += 8;
+		*(long long *)p = WORD_NUMBER;
+		*(long long *)p <<= 32;
+		*(long long *)p |= WORD_NUMBER;
+		break;
+	case 20:
+		*(long long *)p = 1;
+		p += 8;
+		*(long long *)p = 2;
+		p += 8;
+		*(int *)p = WORD_NUMBER;
+		break;
+	case 24:
+		*(long long *)p = 1;
+		p += 8;
+		*(long long *)p = 2;
+		p += 8;
+		*(long long *)p = LONG_NUMBER;
+		break;
+	case 28:
+		*(long long *)p = BYTE_NUMBER;
+		p += 8;
+		*(long long *)p = SHORT_NUMBER;
+		p += 8;
+		*(long long *)p = LONG_NUMBER;
+		p += 8;
+		*(int *)p = WORD_NUMBER;
+		break;
+	case 32:
+		*(long long *)p = BYTE_NUMBER;
+		p += 8;
+		*(long long *)p = SHORT_NUMBER;
+		p += 8;
+		*(long long *)p = 3;
+		p += 8;
+		*(long long *)p = LONG_NUMBER;
+		break;
+	}
+
+	return 1;
+}
+
+static __init void store_return(struct ftrace_graph_ret *trace,
+				struct fgraph_ops *gops)
+{
+	const char *type = fgraph_store_type_name;
+	long long expect[4] = { 0, 0, 0, 0};
+	long long found[4] = { -1, 0, 0, 0};
+	char *p;
+	int i;
+
+	p = fgraph_retrieve_data();
+	if (!p) {
+		snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+			 "Failed to retrieve %s\n", type);
+		fgraph_error_str = fgraph_error_str_buf;
+		return;
+	}
+
+	switch (fgraph_store_size) {
+	case 1:
+		expect[0] = BYTE_NUMBER;
+		found[0] = *(char *)p;
+		break;
+	case 2:
+		expect[0] = SHORT_NUMBER;
+		found[0] = *(short *)p;
+		break;
+	case 4:
+		expect[0] = WORD_NUMBER;
+		found[0] = *(int *)p;
+		break;
+	case 8:
+		expect[0] = LONG_NUMBER;
+		found[0] = *(long long *)p;
+		break;
+	case 12:
+		expect[0] = LONG_NUMBER;
+		found[0] = *(long long *)p;
+		p += 8;
+		expect[1] = WORD_NUMBER;
+		found[1] = *(int *)p;
+		break;
+	case 16:
+		expect[0]= LONG_NUMBER;
+		found[0] = *(long long *)p;
+		p += 8;
+		found[1] = *(long long *)p;
+		expect[1] = WORD_NUMBER;
+		expect[1] <<= 32;
+		expect[1] |= WORD_NUMBER;
+		break;
+	case 20:
+		expect[0] = 1;
+		found[0] = *(long long *)p;
+		p += 8;
+		found[1] = *(long long *)p;
+		expect[1] = 2;
+		p += 8;
+		found[2] = *(int *)p;
+		expect[2] = WORD_NUMBER;
+		break;
+	case 24:
+		expect[0] = 1;
+		found[0] = *(long long *)p;
+		p += 8;
+		found[1] = *(long long *)p;
+		expect[1] = 2;
+		p += 8;
+		found[2] = *(long long *)p;
+		expect[2]  = LONG_NUMBER;
+		break;
+	case 28:
+		found[0] = *(long long *)p;
+		expect[0] = BYTE_NUMBER;
+		p += 8;
+		found[1] = *(long long *)p;
+		expect[1] = SHORT_NUMBER;
+		p += 8;
+		found[2] = *(long long *)p;
+		expect[2] = LONG_NUMBER;
+		p += 8;
+		found[3] = *(int *)p;
+		expect[3] = WORD_NUMBER;
+		break;
+	case 32:
+		found[0] = *(long long *)p;
+		expect[0] = BYTE_NUMBER;
+		p += 8;
+		found[1] = *(long long *)p;
+		expect[1] = SHORT_NUMBER;
+		p += 8;
+		found[2] = *(long long *)p;
+		expect[2] = 3;
+		p += 8;
+		found[3] = *(long long *)p;
+		expect[3] = LONG_NUMBER;
+		break;
+	}
+
+	for (i = 0; i < 4; i++) {
+		if (found[i] != expect[i]) {
+			snprintf(fgraph_error_str_buf,
+				 sizeof(fgraph_error_str_buf),
+				 "%s [word %d] returned not %lld but %lld\n",
+				 type, i, expect[i], found[i]);
+			fgraph_error_str = fgraph_error_str_buf;
+			return;
+		}
+	}
+	fgraph_error_str = NULL;
+}
+
+static struct fgraph_ops store_bytes __initdata = {
+	.entryfunc		= store_entry,
+	.retfunc		= store_return,
+};
+
+static int __init test_graph_storage_type(const char *name, int size)
+{
+	char *func_name;
+	int len;
+	int ret;
+
+	fgraph_store_type_name = name;
+	fgraph_store_size = size;
+
+	snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+		 "Failed to execute storage %s\n", name);
+	fgraph_error_str = fgraph_error_str_buf;
+
+	printk(KERN_CONT "PASSED\n");
+	pr_info("Testing fgraph storage of %d byte%s: ", size, size > 1 ? "s" : "");
+
+	func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
+	len = strlen(func_name);
+
+	ret = ftrace_set_filter(&store_bytes.ops, func_name, len, 1);
+	if (ret && ret != -ENODEV) {
+		pr_cont("*Could not set filter* ");
+		return -1;
+	}
+
+	ret = register_ftrace_graph(&store_bytes);
+	if (ret) {
+		printk(KERN_WARNING "Failed to init store_bytes fgraph tracing\n");
+		return -1;
+	}
+
+	DYN_FTRACE_TEST_NAME();
+
+	unregister_ftrace_graph(&store_bytes);
+
+	if (fgraph_error_str) {
+		printk(KERN_CONT "*** %s ***", fgraph_error_str);
+		return -1;
+	}
+
+	return 0;
+}
+/* Test the storage passed across function_graph entry and return */
+static __init int test_graph_storage(void)
+{
+	int ret;
+
+	ret = test_graph_storage_type("byte", 1);
+	if (ret)
+		return ret;
+	ret = test_graph_storage_type("short", 2);
+	if (ret)
+		return ret;
+	ret = test_graph_storage_type("word", 4);
+	if (ret)
+		return ret;
+	ret = test_graph_storage_type("long long", 8);
+	if (ret)
+		return ret;
+	ret = test_graph_storage_type("12 bytes", 12);
+	if (ret)
+		return ret;
+	ret = test_graph_storage_type("16 bytes", 16);
+	if (ret)
+		return ret;
+#if BITS_PER_LONG == 64
+	ret = test_graph_storage_type("20 bytes", 20);
+	if (ret)
+		return ret;
+	ret = test_graph_storage_type("24 bytes", 24);
+	if (ret)
+		return ret;
+	ret = test_graph_storage_type("28 bytes", 28);
+	if (ret)
+		return ret;
+	ret = test_graph_storage_type("32 bytes", 32);
+	if (ret)
+		return ret;
+#endif
+	return 0;
+}
+#else
+static inline int test_graph_storage(void) { return 0; }
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
 /* Maximum number of functions to trace before diagnosing a hang */
 #define GRAPH_MAX_FUNC_TEST	100000000
 
@@ -805,6 +1113,8 @@ trace_selftest_startup_function_graph(struct tracer *trace,
 		goto out;
 	}
 
+	ret = test_graph_storage();
+
 	/* Don't test dynamic tracing, the function tracer already did */
 
 out:
-- 
2.20.1