LXR linux/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
   9extern void my_direct_func(unsigned long ip);
  10
  11void my_direct_func(unsigned long ip)
  12{
  13        trace_printk("ip %lx\n", ip);
  14}
  15
  16extern void my_tramp(void *);
  17
  18#ifdef CONFIG_X86_64
  19
  20asm (
  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
  41asm (
  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
  64static struct ftrace_ops direct;
  65
  66static 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
  74static void __exit ftrace_direct_multi_exit(void)
  75{
  76        unregister_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
  77}
  78
  79module_init(ftrace_direct_multi_init);
  80module_exit(ftrace_direct_multi_exit);
  81
  82MODULE_AUTHOR("Jiri Olsa");
  83MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
  84MODULE_LICENSE("GPL");
  85