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"); 148