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author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-11-08 21:12:33 +0300 |
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committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-11-13 17:36:49 +0300 |
commit | b06457c83af669bb9ef71f5b84a3132657dce8a1 (patch) | |
tree | 0358038475936f4553ed8a63e4bbaa32b0469af7 /samples/ftrace/ftrace-direct.c | |
parent | 013bf0da0474816f57739daa006c8564ad7396a3 (diff) | |
download | linux-b06457c83af669bb9ef71f5b84a3132657dce8a1.tar.xz |
ftrace: Add sample module that uses register_ftrace_direct()
Add a sample module that shows a simple use case for
regsiter_ftrace_direct(), and how to use it.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'samples/ftrace/ftrace-direct.c')
-rw-r--r-- | samples/ftrace/ftrace-direct.c | 45 |
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..1483f067b000 --- /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("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"); |