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 #ifndef CONFIG_ARM64
   7 #include <asm/asm-offsets.h>
   8 #endif
   9
  10 extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
  11                            unsigned int flags, struct pt_regs *regs);
  12
  13 void my_direct_func(struct vm_area_struct *vma, unsigned long address,
  14                     unsigned int flags, struct pt_regs *regs)
  15 {
  16         trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n",
  17                      vma, address, flags, regs);
  18 }
  19
  20 extern void my_tramp(void *);
  21
  22 #ifdef CONFIG_X86_64
  23
  24 #include <asm/ibt.h>
  25 #include <asm/nospec-branch.h>
  26
  27 asm (
  28 "       .pushsection    .text, \"ax\", @progbits\n"
  29 "       .type           my_tramp, @function\n"
  30 "       .globl          my_tramp\n"
  31 "   my_tramp:"
  32         ASM_ENDBR
  33 "       pushq %rbp\n"
  34 "       movq %rsp, %rbp\n"
  35         CALL_DEPTH_ACCOUNT
  36 "       pushq %rdi\n"
  37 "       pushq %rsi\n"
  38 "       pushq %rdx\n"
  39 "       pushq %rcx\n"
  40 "       call my_direct_func\n"
  41 "       popq %rcx\n"
  42 "       popq %rdx\n"
  43 "       popq %rsi\n"
  44 "       popq %rdi\n"
  45 "       leave\n"
  46         ASM_RET
  47 "       .size           my_tramp, .-my_tramp\n"
  48 "       .popsection\n"
  49 );
  50
  51 #endif /* CONFIG_X86_64 */
  52
  53 #ifdef CONFIG_S390
  54
  55 asm (
  56 "       .pushsection    .text, \"ax\", @progbits\n"
  57 "       .type           my_tramp, @function\n"
  58 "       .globl          my_tramp\n"
  59 "   my_tramp:"
  60 "       lgr             %r1,%r15\n"
  61 "       stmg            %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
  62 "       stg             %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
  63 "       aghi            %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
  64 "       stg             %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
  65 "       brasl           %r14,my_direct_func\n"
  66 "       aghi            %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
  67 "       lmg             %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
  68 "       lg              %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
  69 "       lgr             %r1,%r0\n"
  70 "       br              %r1\n"
  71 "       .size           my_tramp, .-my_tramp\n"
  72 "       .popsection\n"
  73 );
  74
  75 #endif /* CONFIG_S390 */
  76
  77 #ifdef CONFIG_ARM64
  78
  79 asm (
  80 "       .pushsection    .text, \"ax\", @progbits\n"
  81 "       .type           my_tramp, @function\n"
  82 "       .globl          my_tramp\n"
  83 "   my_tramp:"
  84 "       hint    34\n" // bti    c
  85 "       sub     sp, sp, #48\n"
  86 "       stp     x9, x30, [sp]\n"
  87 "       stp     x0, x1, [sp, #16]\n"
  88 "       stp     x2, x3, [sp, #32]\n"
  89 "       bl      my_direct_func\n"
  90 "       ldp     x30, x9, [sp]\n"
  91 "       ldp     x0, x1, [sp, #16]\n"
  92 "       ldp     x2, x3, [sp, #32]\n"
  93 "       add     sp, sp, #48\n"
  94 "       ret     x9\n"
  95 "       .size           my_tramp, .-my_tramp\n"
  96 "       .popsection\n"
  97 );
  98
  99 #endif /* CONFIG_ARM64 */
 100
 101 #ifdef CONFIG_LOONGARCH
 102
 103 asm (
 104 "       .pushsection    .text, \"ax\", @progbits\n"
 105 "       .type           my_tramp, @function\n"
 106 "       .globl          my_tramp\n"
 107 "   my_tramp:\n"
 108 "       addi.d  $sp, $sp, -48\n"
 109 "       st.d    $a0, $sp, 0\n"
 110 "       st.d    $a1, $sp, 8\n"
 111 "       st.d    $a2, $sp, 16\n"
 112 "       st.d    $t0, $sp, 24\n"
 113 "       st.d    $ra, $sp, 32\n"
 114 "       bl      my_direct_func\n"
 115 "       ld.d    $a0, $sp, 0\n"
 116 "       ld.d    $a1, $sp, 8\n"
 117 "       ld.d    $a2, $sp, 16\n"
 118 "       ld.d    $t0, $sp, 24\n"
 119 "       ld.d    $ra, $sp, 32\n"
 120 "       addi.d  $sp, $sp, 48\n"
 121 "       jr      $t0\n"
 122 "       .size           my_tramp, .-my_tramp\n"
 123 "       .popsection\n"
 124 );
 125
 126 #endif /* CONFIG_LOONGARCH */
 127
 128 static struct ftrace_ops direct;
 129
 130 static int __init ftrace_direct_init(void)
 131 {
 132         ftrace_set_filter_ip(&direct, (unsigned long) handle_mm_fault, 0, 0);
 133
 134         return register_ftrace_direct(&direct, (unsigned long) my_tramp);
 135 }
 136
 137 static void __exit ftrace_direct_exit(void)
 138 {
 139         unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true);
 140 }
 141
 142 module_init(ftrace_direct_init);
 143 module_exit(ftrace_direct_exit);
 144
 145 MODULE_AUTHOR("Steven Rostedt");
 146 MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
 147 MODULE_LICENSE("GPL");