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 #include <asm/asm-offsets.h>
   7
   8 extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
   9                            unsigned int flags, struct pt_regs *regs);
  10
  11 void my_direct_func(struct vm_area_struct *vma, unsigned long address,
  12                     unsigned int flags, struct pt_regs *regs)
  13 {
  14         trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n",
  15                      vma, address, flags, regs);
  16 }
  17
  18 extern void my_tramp(void *);
  19
  20 #ifdef CONFIG_X86_64
  21
  22 #include <asm/ibt.h>
  23 #include <asm/nospec-branch.h>
  24
  25 asm (
  26 "       .pushsection    .text, \"ax\", @progbits\n"
  27 "       .type           my_tramp, @function\n"
  28 "       .globl          my_tramp\n"
  29 "   my_tramp:"
  30         ASM_ENDBR
  31 "       pushq %rbp\n"
  32 "       movq %rsp, %rbp\n"
  33         CALL_DEPTH_ACCOUNT
  34 "       pushq %rdi\n"
  35 "       pushq %rsi\n"
  36 "       pushq %rdx\n"
  37 "       pushq %rcx\n"
  38 "       call my_direct_func\n"
  39 "       popq %rcx\n"
  40 "       popq %rdx\n"
  41 "       popq %rsi\n"
  42 "       popq %rdi\n"
  43 "       leave\n"
  44         ASM_RET
  45 "       .size           my_tramp, .-my_tramp\n"
  46 "       .popsection\n"
  47 );
  48
  49 #endif /* CONFIG_X86_64 */
  50
  51 #ifdef CONFIG_S390
  52
  53 asm (
  54 "       .pushsection    .text, \"ax\", @progbits\n"
  55 "       .type           my_tramp, @function\n"
  56 "       .globl          my_tramp\n"
  57 "   my_tramp:"
  58 "       lgr             %r1,%r15\n"
  59 "       stmg            %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
  60 "       stg             %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
  61 "       aghi            %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
  62 "       stg             %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
  63 "       brasl           %r14,my_direct_func\n"
  64 "       aghi            %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
  65 "       lmg             %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
  66 "       lg              %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
  67 "       lgr             %r1,%r0\n"
  68 "       br              %r1\n"
  69 "       .size           my_tramp, .-my_tramp\n"
  70 "       .popsection\n"
  71 );
  72
  73 #endif /* CONFIG_S390 */
  74
  75 #ifdef CONFIG_LOONGARCH
  76
  77 asm (
  78 "       .pushsection    .text, \"ax\", @progbits\n"
  79 "       .type           my_tramp, @function\n"
  80 "       .globl          my_tramp\n"
  81 "   my_tramp:\n"
  82 "       addi.d  $sp, $sp, -48\n"
  83 "       st.d    $a0, $sp, 0\n"
  84 "       st.d    $a1, $sp, 8\n"
  85 "       st.d    $a2, $sp, 16\n"
  86 "       st.d    $t0, $sp, 24\n"
  87 "       st.d    $ra, $sp, 32\n"
  88 "       bl      my_direct_func\n"
  89 "       ld.d    $a0, $sp, 0\n"
  90 "       ld.d    $a1, $sp, 8\n"
  91 "       ld.d    $a2, $sp, 16\n"
  92 "       ld.d    $t0, $sp, 24\n"
  93 "       ld.d    $ra, $sp, 32\n"
  94 "       addi.d  $sp, $sp, 48\n"
  95 "       jr      $t0\n"
  96 "       .size           my_tramp, .-my_tramp\n"
  97 "       .popsection\n"
  98 );
  99
 100 #endif /* CONFIG_LOONGARCH */
 101
 102 static struct ftrace_ops direct;
 103
 104 static int __init ftrace_direct_init(void)
 105 {
 106         ftrace_set_filter_ip(&direct, (unsigned long) handle_mm_fault, 0, 0);
 107
 108         return register_ftrace_direct(&direct, (unsigned long) my_tramp);
 109 }
 110
 111 static void __exit ftrace_direct_exit(void)
 112 {
 113         unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true);
 114 }
 115
 116 module_init(ftrace_direct_init);
 117 module_exit(ftrace_direct_exit);
 118
 119 MODULE_AUTHOR("Steven Rostedt");
 120 MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
 121 MODULE_LICENSE("GPL");