samples/ftrace/ftrace-direct-multi.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 #include <linux/sched/stat.h>
   7 #include <asm/asm-offsets.h>
   8
   9 extern void my_direct_func(unsigned long ip);
  10
  11 void my_direct_func(unsigned long ip)
  12 {
  13         trace_printk("ip %lx\n", ip);
  14 }
  15
  16 extern void my_tramp(void *);
  17
  18 #ifdef CONFIG_X86_64
  19
  20 asm (
  21 "       .pushsection    .text, \"ax\", @progbits\n"
  22 "       .type           my_tramp, @function\n"
  23 "       .globl          my_tramp\n"
  24 "   my_tramp:"
  25 "       pushq %rbp\n"
  26 "       movq %rsp, %rbp\n"
  27 "       pushq %rdi\n"
  28 "       movq 8(%rbp), %rdi\n"
  29 "       call my_direct_func\n"
  30 "       popq %rdi\n"
  31 "       leave\n"
  32 "       ret\n"
  33 "       .size           my_tramp, .-my_tramp\n"
  34 "       .popsection\n"
  35 );
  36
  37 #endif /* CONFIG_X86_64 */
  38
  39 #ifdef CONFIG_S390
  40
  41 asm (
  42 "       .pushsection    .text, \"ax\", @progbits\n"
  43 "       .type           my_tramp, @function\n"
  44 "       .globl          my_tramp\n"
  45 "   my_tramp:"
  46 "       lgr             %r1,%r15\n"
  47 "       stmg            %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
  48 "       stg             %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
  49 "       aghi            %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
  50 "       stg             %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
  51 "       lgr             %r2,%r0\n"
  52 "       brasl           %r14,my_direct_func\n"
  53 "       aghi            %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
  54 "       lmg             %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
  55 "       lg              %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
  56 "       lgr             %r1,%r0\n"
  57 "       br              %r1\n"
  58 "       .size           my_tramp, .-my_tramp\n"
  59 "       .popsection\n"
  60 );
  61
  62 #endif /* CONFIG_S390 */
  63
  64 static struct ftrace_ops direct;
  65
  66 static int __init ftrace_direct_multi_init(void)
  67 {
  68         ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
  69         ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
  70
  71         return register_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
  72 }
  73
  74 static void __exit ftrace_direct_multi_exit(void)
  75 {
  76         unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
  77 }
  78
  79 module_init(ftrace_direct_multi_init);
  80 module_exit(ftrace_direct_multi_exit);
  81
  82 MODULE_AUTHOR("Jiri Olsa");
  83 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
  84 MODULE_LICENSE("GPL");