1 files changed, 59 insertions, 0 deletions
diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
new file mode 100644
index 000000000..4bdd67916
--- /dev/null
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+
+#include <linux/mm.h> /* for handle_mm_fault() */
+#include <linux/ftrace.h>
+
+extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
+			   unsigned int flags, struct pt_regs *regs);
+
+void my_direct_func(struct vm_area_struct *vma, unsigned long address,
+		    unsigned int flags, struct pt_regs *regs)
+{
+	trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n",
+		     vma, address, flags, regs);
+}
+
+extern void my_tramp(void *);
+
+asm (
+"	.pushsection    .text, \"ax\", @progbits\n"
+"	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
+"   my_tramp:"
+"	pushq %rbp\n"
+"	movq %rsp, %rbp\n"
+"	pushq %rdi\n"
+"	pushq %rsi\n"
+"	pushq %rdx\n"
+"	pushq %rcx\n"
+"	call my_direct_func\n"
+"	popq %rcx\n"
+"	popq %rdx\n"
+"	popq %rsi\n"
+"	popq %rdi\n"
+"	leave\n"
+	ASM_RET
+"	.size		my_tramp, .-my_tramp\n"
+"	.popsection\n"
+);
+
+
+static int __init ftrace_direct_init(void)
+{
+	return register_ftrace_direct((unsigned long)handle_mm_fault,
+				     (unsigned long)my_tramp);
+}
+
+static void __exit ftrace_direct_exit(void)
+{
+	unregister_ftrace_direct((unsigned long)handle_mm_fault,
+				 (unsigned long)my_tramp);
+}
+
+module_init(ftrace_direct_init);
+module_exit(ftrace_direct_exit);
+
+MODULE_AUTHOR("Steven Rostedt");
+MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
+MODULE_LICENSE("GPL");