1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/module.h> 3 4 #include <linux/sched.h> /* for wake_up_process() */ 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 task_struct *p); 11 12 void my_direct_func(struct task_struct *p) 13 { 14 trace_printk("waking up %s-%d\n", p->comm, p->pid); 15 } 16 17 extern void my_tramp(void *); 18 19 #ifdef CONFIG_X86_64 20 21 #include <asm/ibt.h> 22 #include <asm/nospec-branch.h> 23 24 asm ( 25 " .pushsection .text, \"ax\", @progbits\n" 26 " .type my_tramp, @function\n" 27 " .globl my_tramp\n" 28 " my_tramp:" 29 ASM_ENDBR 30 " pushq %rbp\n" 31 " movq %rsp, %rbp\n" 32 CALL_DEPTH_ACCOUNT 33 " pushq %rdi\n" 34 " call my_direct_func\n" 35 " popq %rdi\n" 36 " leave\n" 37 ASM_RET 38 " .size my_tramp, .-my_tramp\n" 39 " .popsection\n" 40 ); 41 42 #endif /* CONFIG_X86_64 */ 43 44 #ifdef CONFIG_S390 45 46 asm ( 47 " .pushsection .text, \"ax\", @progbits\n" 48 " .type my_tramp, @function\n" 49 " .globl my_tramp\n" 50 " my_tramp:" 51 " lgr %r1,%r15\n" 52 " stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 53 " stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 54 " aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" 55 " stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" 56 " brasl %r14,my_direct_func\n" 57 " aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" 58 " lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 59 " lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 60 " lgr %r1,%r0\n" 61 " br %r1\n" 62 " .size my_tramp, .-my_tramp\n" 63 " .popsection\n" 64 ); 65 66 #endif /* CONFIG_S390 */ 67 68 #ifdef CONFIG_ARM64 69 70 asm ( 71 " .pushsection .text, \"ax\", @progbits\n" 72 " .type my_tramp, @function\n" 73 " .globl my_tramp\n" 74 " my_tramp:" 75 " hint 34\n" // bti c 76 " sub sp, sp, #32\n" 77 " stp x9, x30, [sp]\n" 78 " str x0, [sp, #16]\n" 79 " bl my_direct_func\n" 80 " ldp x30, x9, [sp]\n" 81 " ldr x0, [sp, #16]\n" 82 " add sp, sp, #32\n" 83 " ret x9\n" 84 " .size my_tramp, .-my_tramp\n" 85 " .popsection\n" 86 ); 87 88 #endif /* CONFIG_ARM64 */ 89 90 #ifdef CONFIG_LOONGARCH 91 92 asm ( 93 " .pushsection .text, \"ax\", @progbits\n" 94 " .type my_tramp, @function\n" 95 " .globl my_tramp\n" 96 " my_tramp:\n" 97 " addi.d $sp, $sp, -32\n" 98 " st.d $a0, $sp, 0\n" 99 " st.d $t0, $sp, 8\n" 100 " st.d $ra, $sp, 16\n" 101 " bl my_direct_func\n" 102 " ld.d $a0, $sp, 0\n" 103 " ld.d $t0, $sp, 8\n" 104 " ld.d $ra, $sp, 16\n" 105 " addi.d $sp, $sp, 32\n" 106 " jr $t0\n" 107 " .size my_tramp, .-my_tramp\n" 108 " .popsection\n" 109 ); 110 111 #endif /* CONFIG_LOONGARCH */ 112 113 static struct ftrace_ops direct; 114 115 static int __init ftrace_direct_init(void) 116 { 117 ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0); 118 119 return register_ftrace_direct(&direct, (unsigned long) my_tramp); 120 } 121 122 static void __exit ftrace_direct_exit(void) 123 { 124 unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true); 125 } 126 127 module_init(ftrace_direct_init); 128 module_exit(ftrace_direct_exit); 129 130 MODULE_AUTHOR("Steven Rostedt"); 131 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()"); 132 MODULE_LICENSE("GPL"); 133