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Diffstat (limited to 'samples/ftrace/ftrace-direct.c')
-rw-r--r--samples/ftrace/ftrace-direct.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
new file mode 100644
index 000000000000..a2e3063bd306
--- /dev/null
+++ b/samples/ftrace/ftrace-direct.c
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+
+#include <linux/sched.h> /* for wake_up_process() */
+#include <linux/ftrace.h>
+
+void my_direct_func(struct task_struct *p)
+{
+ trace_printk("waking up %s-%d\n", p->comm, p->pid);
+}
+
+extern void my_tramp(void *);
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" my_tramp:"
+" pushq %rbp\n"
+" movq %rsp, %rbp\n"
+" pushq %rdi\n"
+" call my_direct_func\n"
+" popq %rdi\n"
+" leave\n"
+" ret\n"
+" .popsection\n"
+);
+
+
+static int __init ftrace_direct_init(void)
+{
+ return register_ftrace_direct((unsigned long)wake_up_process,
+ (unsigned long)my_tramp);
+}
+
+static void __exit ftrace_direct_exit(void)
+{
+ unregister_ftrace_direct((unsigned long)wake_up_process,
+ (unsigned long)my_tramp);
+}
+
+module_init(ftrace_direct_init);
+module_exit(ftrace_direct_exit);
+
+MODULE_AUTHOR("Steven Rostedt");
+MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()");
+MODULE_LICENSE("GPL");