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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: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Jiri Olsa 2021-10-08 11:13:36 +02:00 committed by Steven Rostedt (VMware)
parent ccf5a89efd
commit 5fae941b9a
2 changed files with 53 additions and 0 deletions
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1
samples/ftrace/Makefile
View File

@ -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

52
samples/ftrace/ftrace-direct-multi.c Normal file
View File

@ -0,0 +1,52 @@
// 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");