LXR linux/samples/ftrace/ftrace-direct-too.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2#include <linux/module.h>
   3
   4#include <linux/mm.h> /* for handle_mm_fault() */
   5#include <linux/ftrace.h>
   6
   7void my_direct_func(struct vm_area_struct *vma,
   8                        unsigned long address, unsigned int flags)
   9{
  10        trace_printk("handle mm fault vma=%p address=%lx flags=%x\n",
  11                     vma, address, flags);
  12}
  13
  14extern void my_tramp(void *);
  15
  16asm (
  17"       .pushsection    .text, \"ax\", @progbits\n"
  18"       .type           my_tramp, @function\n"
  19"       .globl          my_tramp\n"
  20"   my_tramp:"
  21"       pushq %rbp\n"
  22"       movq %rsp, %rbp\n"
  23"       pushq %rdi\n"
  24"       pushq %rsi\n"
  25"       pushq %rdx\n"
  26"       call my_direct_func\n"
  27"       popq %rdx\n"
  28"       popq %rsi\n"
  29"       popq %rdi\n"
  30"       leave\n"
  31"       ret\n"
  32"       .size           my_tramp, .-my_tramp\n"
  33"       .popsection\n"
  34);
  35
  36
  37static int __init ftrace_direct_init(void)
  38{
  39        return register_ftrace_direct((unsigned long)handle_mm_fault,
  40                                     (unsigned long)my_tramp);
  41}
  42
  43static void __exit ftrace_direct_exit(void)
  44{
  45        unregister_ftrace_direct((unsigned long)handle_mm_fault,
  46                                 (unsigned long)my_tramp);
  47}
  48
  49module_init(ftrace_direct_init);
  50module_exit(ftrace_direct_exit);
  51
  52MODULE_AUTHOR("Steven Rostedt");
  53MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
  54MODULE_LICENSE("GPL");
  55