| 1 | // SPDX-License-Identifier: GPL-2.0-only |
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| 2 | #include <linux/module.h> |
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| 3 | |
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| 4 | #include <linux/mm.h> /* for handle_mm_fault() */ |
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| 5 | #include <linux/ftrace.h> |
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| 6 | #ifndef CONFIG_ARM64 |
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| 7 | #include <asm/asm-offsets.h> |
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| 8 | #endif |
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| 9 | |
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| 10 | extern void my_direct_func(struct vm_area_struct *vma, unsigned long address, |
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| 11 | unsigned int flags, struct pt_regs *regs); |
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| 12 | |
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| 13 | void my_direct_func(struct vm_area_struct *vma, unsigned long address, |
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| 14 | unsigned int flags, struct pt_regs *regs) |
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| 15 | { |
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| 16 | trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n" , |
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| 17 | vma, address, flags, regs); |
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| 18 | } |
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| 19 | |
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| 20 | extern void my_tramp(void *); |
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| 21 | |
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| 22 | #ifdef CONFIG_RISCV |
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| 23 | #include <asm/asm.h> |
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| 24 | |
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| 25 | asm ( |
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| 26 | " .pushsection .text, \"ax\", @progbits\n" |
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| 27 | " .type my_tramp, @function\n" |
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| 28 | " .globl my_tramp\n" |
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| 29 | " my_tramp:\n" |
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| 30 | " addi sp,sp,-5*" SZREG"\n" |
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| 31 | " " REG_S" a0,0*" SZREG"(sp)\n" |
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| 32 | " " REG_S" a1,1*" SZREG"(sp)\n" |
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| 33 | " " REG_S" a2,2*" SZREG"(sp)\n" |
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| 34 | " " REG_S" t0,3*" SZREG"(sp)\n" |
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| 35 | " " REG_S" ra,4*" SZREG"(sp)\n" |
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| 36 | " call my_direct_func\n" |
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| 37 | " " REG_L" a0,0*" SZREG"(sp)\n" |
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| 38 | " " REG_L" a1,1*" SZREG"(sp)\n" |
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| 39 | " " REG_L" a2,2*" SZREG"(sp)\n" |
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| 40 | " " REG_L" t0,3*" SZREG"(sp)\n" |
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| 41 | " " REG_L" ra,4*" SZREG"(sp)\n" |
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| 42 | " addi sp,sp,5*" SZREG"\n" |
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| 43 | " jr t0\n" |
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| 44 | " .size my_tramp, .-my_tramp\n" |
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| 45 | " .popsection\n" |
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| 46 | ); |
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| 47 | |
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| 48 | #endif /* CONFIG_RISCV */ |
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| 49 | |
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| 50 | #ifdef CONFIG_X86_64 |
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| 51 | |
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| 52 | #include <asm/ibt.h> |
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| 53 | #include <asm/nospec-branch.h> |
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| 54 | |
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| 55 | asm ( |
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| 56 | " .pushsection .text, \"ax\", @progbits\n" |
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| 57 | " .type my_tramp, @function\n" |
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| 58 | " .globl my_tramp\n" |
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| 59 | " my_tramp:" |
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| 60 | ASM_ENDBR |
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| 61 | " pushq %rbp\n" |
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| 62 | " movq %rsp, %rbp\n" |
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| 63 | CALL_DEPTH_ACCOUNT |
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| 64 | " pushq %rdi\n" |
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| 65 | " pushq %rsi\n" |
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| 66 | " pushq %rdx\n" |
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| 67 | " pushq %rcx\n" |
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| 68 | " call my_direct_func\n" |
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| 69 | " popq %rcx\n" |
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| 70 | " popq %rdx\n" |
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| 71 | " popq %rsi\n" |
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| 72 | " popq %rdi\n" |
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| 73 | " leave\n" |
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| 74 | ASM_RET |
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| 75 | " .size my_tramp, .-my_tramp\n" |
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| 76 | " .popsection\n" |
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| 77 | ); |
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| 78 | |
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| 79 | #endif /* CONFIG_X86_64 */ |
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| 80 | |
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| 81 | #ifdef CONFIG_S390 |
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| 82 | |
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| 83 | asm ( |
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| 84 | " .pushsection .text, \"ax\", @progbits\n" |
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| 85 | " .type my_tramp, @function\n" |
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| 86 | " .globl my_tramp\n" |
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| 87 | " my_tramp:" |
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| 88 | " lgr %r1,%r15\n" |
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| 89 | " stmg %r0,%r5," __stringify(__SF_GPRS)"(%r15)\n" |
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| 90 | " stg %r14," __stringify(__SF_GPRS+8*8)"(%r15)\n" |
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| 91 | " aghi %r15," __stringify(-STACK_FRAME_OVERHEAD)"\n" |
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| 92 | " stg %r1," __stringify(__SF_BACKCHAIN)"(%r15)\n" |
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| 93 | " brasl %r14,my_direct_func\n" |
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| 94 | " aghi %r15," __stringify(STACK_FRAME_OVERHEAD)"\n" |
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| 95 | " lmg %r0,%r5," __stringify(__SF_GPRS)"(%r15)\n" |
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| 96 | " lg %r14," __stringify(__SF_GPRS+8*8)"(%r15)\n" |
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| 97 | " lgr %r1,%r0\n" |
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| 98 | " br %r1\n" |
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| 99 | " .size my_tramp, .-my_tramp\n" |
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| 100 | " .popsection\n" |
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| 101 | ); |
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| 102 | |
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| 103 | #endif /* CONFIG_S390 */ |
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| 104 | |
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| 105 | #ifdef CONFIG_ARM64 |
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| 106 | |
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| 107 | asm ( |
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| 108 | " .pushsection .text, \"ax\", @progbits\n" |
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| 109 | " .type my_tramp, @function\n" |
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| 110 | " .globl my_tramp\n" |
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| 111 | " my_tramp:" |
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| 112 | " hint 34\n" // bti c |
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| 113 | " sub sp, sp, #48\n" |
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| 114 | " stp x9, x30, [sp]\n" |
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| 115 | " stp x0, x1, [sp, #16]\n" |
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| 116 | " stp x2, x3, [sp, #32]\n" |
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| 117 | " bl my_direct_func\n" |
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| 118 | " ldp x30, x9, [sp]\n" |
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| 119 | " ldp x0, x1, [sp, #16]\n" |
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| 120 | " ldp x2, x3, [sp, #32]\n" |
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| 121 | " add sp, sp, #48\n" |
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| 122 | " ret x9\n" |
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| 123 | " .size my_tramp, .-my_tramp\n" |
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| 124 | " .popsection\n" |
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| 125 | ); |
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| 126 | |
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| 127 | #endif /* CONFIG_ARM64 */ |
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| 128 | |
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| 129 | #ifdef CONFIG_LOONGARCH |
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| 130 | |
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| 131 | asm ( |
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| 132 | " .pushsection .text, \"ax\", @progbits\n" |
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| 133 | " .type my_tramp, @function\n" |
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| 134 | " .globl my_tramp\n" |
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| 135 | " my_tramp:\n" |
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| 136 | " addi.d $sp, $sp, -48\n" |
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| 137 | " st.d $a0, $sp, 0\n" |
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| 138 | " st.d $a1, $sp, 8\n" |
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| 139 | " st.d $a2, $sp, 16\n" |
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| 140 | " st.d $t0, $sp, 24\n" |
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| 141 | " st.d $ra, $sp, 32\n" |
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| 142 | " bl my_direct_func\n" |
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| 143 | " ld.d $a0, $sp, 0\n" |
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| 144 | " ld.d $a1, $sp, 8\n" |
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| 145 | " ld.d $a2, $sp, 16\n" |
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| 146 | " ld.d $t0, $sp, 24\n" |
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| 147 | " ld.d $ra, $sp, 32\n" |
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| 148 | " addi.d $sp, $sp, 48\n" |
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| 149 | " jr $t0\n" |
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| 150 | " .size my_tramp, .-my_tramp\n" |
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| 151 | " .popsection\n" |
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| 152 | ); |
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| 153 | |
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| 154 | #endif /* CONFIG_LOONGARCH */ |
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| 155 | |
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| 156 | static struct ftrace_ops direct; |
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| 157 | |
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| 158 | static int __init ftrace_direct_init(void) |
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| 159 | { |
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| 160 | ftrace_set_filter_ip(ops: &direct, ip: (unsigned long) handle_mm_fault, remove: 0, reset: 0); |
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| 161 | |
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| 162 | return register_ftrace_direct(ops: &direct, addr: (unsigned long) my_tramp); |
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| 163 | } |
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| 164 | |
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| 165 | static void __exit ftrace_direct_exit(void) |
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| 166 | { |
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| 167 | unregister_ftrace_direct(ops: &direct, addr: (unsigned long)my_tramp, free_filters: true); |
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| 168 | } |
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| 169 | |
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| 170 | module_init(ftrace_direct_init); |
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| 171 | module_exit(ftrace_direct_exit); |
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| 172 | |
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| 173 | MODULE_AUTHOR("Steven Rostedt" ); |
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| 174 | MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()" ); |
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| 175 | MODULE_LICENSE("GPL" ); |
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| 176 | |
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