Commit 5fae941b authored by Jiri Olsa's avatar Jiri Olsa Committed by Steven Rostedt (VMware)
Browse files

ftrace/samples: Add multi direct interface test module 

Adding simple module that uses multi direct interface:

  register_ftrace_direct_multi
  unregister_ftrace_direct_multi

The init function registers trampoline for 2 functions,
and exit function unregisters them.

Link: https://lkml.kernel.org/r/20211008091336.33616-9-jolsa@kernel.org



Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent ccf5a89e

samples/ftrace/Makefile

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@@ -3,6 +3,7 @@ 
obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct.o

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

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

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



CFLAGS_sample-trace-array.o := -I$(src)

obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += sample-trace-array.o

samples/ftrace/ftrace-direct-multi.c

0 → 100644
+52 −0
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// SPDX-License-Identifier: GPL-2.0-only

#include <linux/module.h>



#include <linux/mm.h> /* for handle_mm_fault() */

#include <linux/ftrace.h>

#include <linux/sched/stat.h>



void my_direct_func(unsigned long ip)

{

	trace_printk("ip %lx\n", ip);

}



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"

"	movq 8(%rbp), %rdi\n"

"	call my_direct_func\n"

"	popq %rdi\n"

"	leave\n"

"	ret\n"

"	.size		my_tramp, .-my_tramp\n"

"	.popsection\n"

);



static struct ftrace_ops direct;



static int __init ftrace_direct_multi_init(void)

{

	ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);

	ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);



	return register_ftrace_direct_multi(&direct, (unsigned long) my_tramp);

}



static void __exit ftrace_direct_multi_exit(void)

{

	unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp);

}



module_init(ftrace_direct_multi_init);

module_exit(ftrace_direct_multi_exit);



MODULE_AUTHOR("Jiri Olsa");

MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");

MODULE_LICENSE("GPL");