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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>
extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
unsigned int flags, struct pt_regs *regs);
void my_direct_func(struct vm_area_struct *vma, unsigned long address,
unsigned int flags, struct pt_regs *regs)
{
trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n",
vma, address, flags, regs);
}
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"
" pushq %rsi\n"
" pushq %rdx\n"
" pushq %rcx\n"
" call my_direct_func\n"
" popq %rcx\n"
" popq %rdx\n"
" popq %rsi\n"
" popq %rdi\n"
" leave\n"
ASM_RET
" .size my_tramp, .-my_tramp\n"
" .popsection\n"
);
static int __init ftrace_direct_init(void)
{
return register_ftrace_direct((unsigned long)handle_mm_fault,
(unsigned long)my_tramp);
}
static void __exit ftrace_direct_exit(void)
{
unregister_ftrace_direct((unsigned long)handle_mm_fault,
(unsigned long)my_tramp);
}
module_init(ftrace_direct_init);
module_exit(ftrace_direct_exit);
MODULE_AUTHOR("Steven Rostedt");
MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
MODULE_LICENSE("GPL");
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