From: "Steven Rostedt (VMware)" <rost...@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.

Co-developed with Masami Hiramatsu:
Link: 
https://lore.kernel.org/linux-trace-kernel/171509110271.162236.11047551496319744627.stgit@devnote2

Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhira...@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
 kernel/trace/trace_selftest.c | 169 ++++++++++++++++++++++++++++++++++
 1 file changed, 169 insertions(+)

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index f8f55fd79e53..fcdc744c245e 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -756,6 +756,173 @@ 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(gops->idx, 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;
+       int size;
+       char *p;
+
+       p = fgraph_retrieve_data(gops->idx, &size);
+       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;
+       }
+       if (fgraph_store_size > size) {
+               snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+                        "Retrieved size %d is smaller than expected %d\n",
+                        size, (int)fgraph_store_size);
+               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;
+
+       pr_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) {
+               pr_warn("Failed to init store_bytes fgraph tracing\n");
+               return -1;
+       }
+
+       DYN_FTRACE_TEST_NAME();
+
+       unregister_ftrace_graph(&store_bytes);
+
+       if (fgraph_error_str) {
+               pr_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 +1080,8 @@ 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 */
-- 
2.43.0



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