ftrace: Add sample module that uses register_ftrace_direct() (b06457c8) · Commits · 戴 / test

samples/Kconfig

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		@@ -19,6 +19,14 @@ config SAMPLE_TRACE_PRINTK
		This builds a module that calls trace_printk() and can be used to
		test various trace_printk() calls from a module.

		config SAMPLE_FTRACE_DIRECT
		tristate "Build register_ftrace_direct() example"
		depends on DYNAMIC_FTRACE_WITH_DIRECT_CALLS && m
		depends on X86_64 # has x86_64 inlined asm
		help
		This builds an ftrace direct function example
		that hooks to wake_up_process and prints the parameters.

		config SAMPLE_KOBJECT
		tristate "Build kobject examples"
		help

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		@@ -17,6 +17,7 @@ obj-$(CONFIG_SAMPLE_RPMSG_CLIENT) += rpmsg/
		subdir-$(CONFIG_SAMPLE_SECCOMP) += seccomp
		obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace_events/
		obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace_printk/
		obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace/
		obj-$(CONFIG_VIDEO_PCI_SKELETON) += v4l/
		obj-y += vfio-mdev/
		subdir-$(CONFIG_SAMPLE_VFS) += vfs

0 → 100644

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		# SPDX-License-Identifier: GPL-2.0-only

		obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct.o

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		// 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("wakeing 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");