[v7,21/36] function_graph: Add selftest for passing local variables

Commit Message

Masami Hiramatsu (Google) Feb. 6, 2024, 3:11 p.m. UTC

From: Steven Rostedt (VMware) <[e-mail]>

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) <[e-mail]>
Signed-off-by: Masami Hiramatsu (Google) <[e-mail]>
---
 Changes in v2:
  - Add reserved size test.
  - Use pr_*() instead of printk(KERN_*).
---
 kernel/trace/trace_selftest.c |  169 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 169 insertions(+)

Comments

Steven Rostedt Feb. 15, 2024, 3:02 p.m. UTC | #1

On Wed,  7 Feb 2024 00:11:22 +0900
"Masami Hiramatsu (Google)" <[e-mail]> wrote:

> From: Steven Rostedt (VMware) <[e-mail]>
> 
> 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) <[e-mail]>
> Signed-off-by: Masami Hiramatsu (Google) <[e-mail]>
> ---
>  Changes in v2:
>   - Add reserved size test.
>   - Use pr_*() instead of printk(KERN_*).
> ---
>  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 f0758afa2f7d..4d86cd4c8c8c 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;
> +	}
> +

What would be an interesting test is to run all versions together. That is,
to attach a callback that stores a byte, a callback that stores a short, a
callback that stores a word and a callback that stores a long, and attach
them all to the same function.

I guess we can add that as a separate patch.

-- Steve


> +	return 1;
> +}
> +

Masami Hiramatsu (Google) Feb. 16, 2024, 8:41 a.m. UTC | #2

On Thu, 15 Feb 2024 10:02:54 -0500
Steven Rostedt <[e-mail]> wrote:

> On Wed,  7 Feb 2024 00:11:22 +0900
> "Masami Hiramatsu (Google)" <[e-mail]> wrote:
> 
> > From: Steven Rostedt (VMware) <[e-mail]>
> > 
> > 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) <[e-mail]>
> > Signed-off-by: Masami Hiramatsu (Google) <[e-mail]>
> > ---
> >  Changes in v2:
> >   - Add reserved size test.
> >   - Use pr_*() instead of printk(KERN_*).
> > ---
> >  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 f0758afa2f7d..4d86cd4c8c8c 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;
> > +	}
> > +
> 
> What would be an interesting test is to run all versions together. That is,
> to attach a callback that stores a byte, a callback that stores a short, a
> callback that stores a word and a callback that stores a long, and attach
> them all to the same function.
> 
> I guess we can add that as a separate patch.

Would you mean we should have different callbacks which stores the different
size of data instead of using switch()?

Thank you,

> 
> -- Steve
> 
> 
> > +	return 1;
> > +}
> > +

Patch

diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index f0758afa2f7d..4d86cd4c8c8c 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 */