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