linux/samples/ftrace/ftrace-direct.c
Josh Poimboeuf 9d907f1ae8 samples/ftrace: Fix asm function ELF annotations
Enable objtool coverage for the sample ftrace modules by adding ELF
annotations to the asm trampoline functions.

  samples/ftrace/ftrace-direct.o: warning: objtool: .text+0x0: unreachable instruction
  samples/ftrace/ftrace-direct-modify.o: warning: objtool: .text+0x0: unreachable instruction
  samples/ftrace/ftrace-direct-too.o: warning: objtool: .text+0x0: unreachable instruction

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2020-05-20 08:30:43 -05:00

48 lines
1.0 KiB
C

// 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("waking up %s-%d\n", p->comm, p->pid);
}
extern void my_tramp(void *);
asm (
" .pushsection .text, \"ax\", @progbits\n"
" .type my_tramp, @function\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"
" .size my_tramp, .-my_tramp\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");