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_RISCV
  23 #include <asm/asm.h>
  24
  25 asm (
  26 "       .pushsection    .text, \"ax\", @progbits\n"
  27 "       .type           my_tramp, @function\n"
  28 "       .globl          my_tramp\n"
  29 "   my_tramp:\n"
  30 "       addi    sp,sp,-5*"SZREG"\n"
  31 "       "REG_S" a0,0*"SZREG"(sp)\n"
  32 "       "REG_S" a1,1*"SZREG"(sp)\n"
  33 "       "REG_S" a2,2*"SZREG"(sp)\n"
  34 "       "REG_S" t0,3*"SZREG"(sp)\n"
  35 "       "REG_S" ra,4*"SZREG"(sp)\n"
  36 "       call    my_direct_func\n"
  37 "       "REG_L" a0,0*"SZREG"(sp)\n"
  38 "       "REG_L" a1,1*"SZREG"(sp)\n"
  39 "       "REG_L" a2,2*"SZREG"(sp)\n"
  40 "       "REG_L" t0,3*"SZREG"(sp)\n"
  41 "       "REG_L" ra,4*"SZREG"(sp)\n"
  42 "       addi    sp,sp,5*"SZREG"\n"
  43 "       jr      t0\n"
  44 "       .size           my_tramp, .-my_tramp\n"
  45 "       .popsection\n"
  46 );
  47
  48 #endif /* CONFIG_RISCV */
  49
  50 #ifdef CONFIG_X86_64
  51
  52 #include <asm/ibt.h>
  53 #include <asm/nospec-branch.h>
  54
  55 asm (
  56 "       .pushsection    .text, \"ax\", @progbits\n"
  57 "       .type           my_tramp, @function\n"
  58 "       .globl          my_tramp\n"
  59 "   my_tramp:"
  60         ASM_ENDBR
  61 "       pushq %rbp\n"
  62 "       movq %rsp, %rbp\n"
  63         CALL_DEPTH_ACCOUNT
  64 "       pushq %rdi\n"
  65 "       pushq %rsi\n"
  66 "       pushq %rdx\n"
  67 "       pushq %rcx\n"
  68 "       call my_direct_func\n"
  69 "       popq %rcx\n"
  70 "       popq %rdx\n"
  71 "       popq %rsi\n"
  72 "       popq %rdi\n"
  73 "       leave\n"
  74         ASM_RET
  75 "       .size           my_tramp, .-my_tramp\n"
  76 "       .popsection\n"
  77 );
  78
  79 #endif /* CONFIG_X86_64 */
  80
  81 #ifdef CONFIG_S390
  82
  83 asm (
  84 "       .pushsection    .text, \"ax\", @progbits\n"
  85 "       .type           my_tramp, @function\n"
  86 "       .globl          my_tramp\n"
  87 "   my_tramp:"
  88 "       lgr             %r1,%r15\n"
  89 "       stmg            %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
  90 "       stg             %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
  91 "       aghi            %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n"
  92 "       stg             %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n"
  93 "       brasl           %r14,my_direct_func\n"
  94 "       aghi            %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n"
  95 "       lmg             %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n"
  96 "       lg              %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n"
  97 "       lgr             %r1,%r0\n"
  98 "       br              %r1\n"
  99 "       .size           my_tramp, .-my_tramp\n"
 100 "       .popsection\n"
 101 );
 102
 103 #endif /* CONFIG_S390 */
 104
 105 #ifdef CONFIG_ARM64
 106
 107 asm (
 108 "       .pushsection    .text, \"ax\", @progbits\n"
 109 "       .type           my_tramp, @function\n"
 110 "       .globl          my_tramp\n"
 111 "   my_tramp:"
 112 "       hint    34\n" // bti    c
 113 "       sub     sp, sp, #48\n"
 114 "       stp     x9, x30, [sp]\n"
 115 "       stp     x0, x1, [sp, #16]\n"
 116 "       stp     x2, x3, [sp, #32]\n"
 117 "       bl      my_direct_func\n"
 118 "       ldp     x30, x9, [sp]\n"
 119 "       ldp     x0, x1, [sp, #16]\n"
 120 "       ldp     x2, x3, [sp, #32]\n"
 121 "       add     sp, sp, #48\n"
 122 "       ret     x9\n"
 123 "       .size           my_tramp, .-my_tramp\n"
 124 "       .popsection\n"
 125 );
 126
 127 #endif /* CONFIG_ARM64 */
 128
 129 #ifdef CONFIG_LOONGARCH
 130
 131 asm (
 132 "       .pushsection    .text, \"ax\", @progbits\n"
 133 "       .type           my_tramp, @function\n"
 134 "       .globl          my_tramp\n"
 135 "   my_tramp:\n"
 136 "       addi.d  $sp, $sp, -48\n"
 137 "       st.d    $a0, $sp, 0\n"
 138 "       st.d    $a1, $sp, 8\n"
 139 "       st.d    $a2, $sp, 16\n"
 140 "       st.d    $t0, $sp, 24\n"
 141 "       st.d    $ra, $sp, 32\n"
 142 "       bl      my_direct_func\n"
 143 "       ld.d    $a0, $sp, 0\n"
 144 "       ld.d    $a1, $sp, 8\n"
 145 "       ld.d    $a2, $sp, 16\n"
 146 "       ld.d    $t0, $sp, 24\n"
 147 "       ld.d    $ra, $sp, 32\n"
 148 "       addi.d  $sp, $sp, 48\n"
 149 "       jr      $t0\n"
 150 "       .size           my_tramp, .-my_tramp\n"
 151 "       .popsection\n"
 152 );
 153
 154 #endif /* CONFIG_LOONGARCH */
 155
 156 static struct ftrace_ops direct;
 157
 158 static int __init ftrace_direct_init(void)
 159 {
 160         ftrace_set_filter_ip(&direct, (unsigned long) handle_mm_fault, 0, 0);
 161
 162         return register_ftrace_direct(&direct, (unsigned long) my_tramp);
 163 }
 164
 165 static void __exit ftrace_direct_exit(void)
 166 {
 167         unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true);
 168 }
 169
 170 module_init(ftrace_direct_init);
 171 module_exit(ftrace_direct_exit);
 172
 173 MODULE_AUTHOR("Steven Rostedt");
 174 MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()");
 175 MODULE_LICENSE("GPL");