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_RISCV 20 #include <asm/asm.h> 21 22 asm ( 23 " .pushsection .text, \"ax\", @progbits\n" 24 " .type my_tramp, @function\n" 25 " .globl my_tramp\n" 26 " my_tramp:\n" 27 " addi sp,sp,-3*"SZREG"\n" 28 " "REG_S" a0,0*"SZREG"(sp)\n" 29 " "REG_S" t0,1*"SZREG"(sp)\n" 30 " "REG_S" ra,2*"SZREG"(sp)\n" 31 " call my_direct_func\n" 32 " "REG_L" a0,0*"SZREG"(sp)\n" 33 " "REG_L" t0,1*"SZREG"(sp)\n" 34 " "REG_L" ra,2*"SZREG"(sp)\n" 35 " addi sp,sp,3*"SZREG"\n" 36 " jr t0\n" 37 " .size my_tramp, .-my_tramp\n" 38 " .popsection\n" 39 ); 40 41 #endif /* CONFIG_RISCV */ 42 43 #ifdef CONFIG_X86_64 44 45 #include <asm/ibt.h> 46 #include <asm/nospec-branch.h> 47 48 asm ( 49 " .pushsection .text, \"ax\", @progbits\n" 50 " .type my_tramp, @function\n" 51 " .globl my_tramp\n" 52 " my_tramp:" 53 ASM_ENDBR 54 " pushq %rbp\n" 55 " movq %rsp, %rbp\n" 56 CALL_DEPTH_ACCOUNT 57 " pushq %rdi\n" 58 " call my_direct_func\n" 59 " popq %rdi\n" 60 " leave\n" 61 ASM_RET 62 " .size my_tramp, .-my_tramp\n" 63 " .popsection\n" 64 ); 65 66 #endif /* CONFIG_X86_64 */ 67 68 #ifdef CONFIG_S390 69 70 asm ( 71 " .pushsection .text, \"ax\", @progbits\n" 72 " .type my_tramp, @function\n" 73 " .globl my_tramp\n" 74 " my_tramp:" 75 " lgr %r1,%r15\n" 76 " stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 77 " stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 78 " aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" 79 " stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" 80 " brasl %r14,my_direct_func\n" 81 " aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" 82 " lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 83 " lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 84 " lgr %r1,%r0\n" 85 " br %r1\n" 86 " .size my_tramp, .-my_tramp\n" 87 " .popsection\n" 88 ); 89 90 #endif /* CONFIG_S390 */ 91 92 #ifdef CONFIG_ARM64 93 94 asm ( 95 " .pushsection .text, \"ax\", @progbits\n" 96 " .type my_tramp, @function\n" 97 " .globl my_tramp\n" 98 " my_tramp:" 99 " hint 34\n" // bti c 100 " sub sp, sp, #32\n" 101 " stp x9, x30, [sp]\n" 102 " str x0, [sp, #16]\n" 103 " bl my_direct_func\n" 104 " ldp x30, x9, [sp]\n" 105 " ldr x0, [sp, #16]\n" 106 " add sp, sp, #32\n" 107 " ret x9\n" 108 " .size my_tramp, .-my_tramp\n" 109 " .popsection\n" 110 ); 111 112 #endif /* CONFIG_ARM64 */ 113 114 #ifdef CONFIG_LOONGARCH 115 116 asm ( 117 " .pushsection .text, \"ax\", @progbits\n" 118 " .type my_tramp, @function\n" 119 " .globl my_tramp\n" 120 " my_tramp:\n" 121 " addi.d $sp, $sp, -32\n" 122 " st.d $a0, $sp, 0\n" 123 " st.d $t0, $sp, 8\n" 124 " st.d $ra, $sp, 16\n" 125 " bl my_direct_func\n" 126 " ld.d $a0, $sp, 0\n" 127 " ld.d $t0, $sp, 8\n" 128 " ld.d $ra, $sp, 16\n" 129 " addi.d $sp, $sp, 32\n" 130 " jr $t0\n" 131 " .size my_tramp, .-my_tramp\n" 132 " .popsection\n" 133 ); 134 135 #endif /* CONFIG_LOONGARCH */ 136 137 static struct ftrace_ops direct; 138 139 static int __init ftrace_direct_init(void) 140 { 141 ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0); 142 143 return register_ftrace_direct(&direct, (unsigned long) my_tramp); 144 } 145 146 static void __exit ftrace_direct_exit(void) 147 { 148 unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true); 149 } 150 151 module_init(ftrace_direct_init); 152 module_exit(ftrace_direct_exit); 153 154 MODULE_AUTHOR("Steven Rostedt"); 155 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()"); 156 MODULE_LICENSE("GPL"); 157