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