[RFC PATCH 16/32] function_graph: Add selftest for passing local variables

Masami Hiramatsu (Google)
2023-11-05T16:09:52Z

From: Steven Rostedt (VMware) <rostedt@goodmis.org>

Add boot up selftest that passes variables from a function entry to a
function exit, and make sure that they do get passed around.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_selftest.c | 161 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 161 insertions(+)

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index e05f7335525c..14966d8509ed 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -756,6 +756,165 @@ 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;
+
+ 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;
+ }
+
+ 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;
+ }
+
+ 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 = 0;
+ long long found = -1;
+ char *p;
+
+ 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 = BYTE_NUMBER;
+ found = *(char *)p;
+ break;
+ case 2:
+ expect = SHORT_NUMBER;
+ found = *(short *)p;
+ break;
+ case 4:
+ expect = WORD_NUMBER;
+ found = *(int *)p;
+ break;
+ case 8:
+ expect = LONG_NUMBER;
+ found = *(long long *)p;
+ break;
+ }
+
+ if (found != expect) {
+ snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+ "%s returned not %lld but %lld\n", type, expect, found);
+ 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;
+ 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

@@ -913,6 +1072,8 @@ trace_selftest_startup_function_graph(struct tracer *trace,
ftrace_set_global_filter(NULL, 0, 1);
#endif

+ ret = test_graph_storage();
+
/* Don't test dynamic tracing, the function tracer already did */
out:
/* Stop it if we failed */