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 #if !defined(CONFIG_ARM64) && !defined(CONFIG_PPC32) 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 #ifdef CONFIG_PPC 157 #include <asm/ppc_asm.h> 158 159 #ifdef CONFIG_PPC64 160 #define STACK_FRAME_SIZE 64 161 #define STACK_FRAME_ARG1 32 162 #define STACK_FRAME_ARG2 40 163 #define STACK_FRAME_ARG3 48 164 #define STACK_FRAME_ARG4 56 165 #else 166 #define STACK_FRAME_SIZE 32 167 #define STACK_FRAME_ARG1 16 168 #define STACK_FRAME_ARG2 20 169 #define STACK_FRAME_ARG3 24 170 #define STACK_FRAME_ARG4 28 171 #endif 172 173 #if defined(CONFIG_PPC64_ELF_ABI_V2) && !defined(CONFIG_PPC_KERNEL_PCREL) 174 #define PPC64_TOC_SAVE_AND_UPDATE \ 175 " std 2, 24(1)\n" \ 176 " bcl 20, 31, 1f\n" \ 177 " 1: mflr 12\n" \ 178 " ld 2, (99f - 1b)(12)\n" 179 #define PPC64_TOC_RESTORE \ 180 " ld 2, 24(1)\n" 181 #define PPC64_TOC \ 182 " 99: .quad .TOC.@tocbase\n" 183 #else 184 #define PPC64_TOC_SAVE_AND_UPDATE "" 185 #define PPC64_TOC_RESTORE "" 186 #define PPC64_TOC "" 187 #endif 188 189 #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE 190 #define PPC_FTRACE_RESTORE_LR \ 191 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" \ 192 " mtlr 0\n" 193 #define PPC_FTRACE_RET \ 194 " blr\n" 195 #else 196 #define PPC_FTRACE_RESTORE_LR \ 197 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" \ 198 " mtctr 0\n" 199 #define PPC_FTRACE_RET \ 200 " mtlr 0\n" \ 201 " bctr\n" 202 #endif 203 204 asm ( 205 " .pushsection .text, \"ax\", @progbits\n" 206 " .type my_tramp, @function\n" 207 " .globl my_tramp\n" 208 " my_tramp:\n" 209 PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" 210 PPC_STLU" 1, -"__stringify(STACK_FRAME_MIN_SIZE)"(1)\n" 211 " mflr 0\n" 212 PPC_STL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" 213 PPC_STLU" 1, -"__stringify(STACK_FRAME_SIZE)"(1)\n" 214 PPC64_TOC_SAVE_AND_UPDATE 215 PPC_STL" 3, "__stringify(STACK_FRAME_ARG1)"(1)\n" 216 PPC_STL" 4, "__stringify(STACK_FRAME_ARG2)"(1)\n" 217 PPC_STL" 5, "__stringify(STACK_FRAME_ARG3)"(1)\n" 218 PPC_STL" 6, "__stringify(STACK_FRAME_ARG4)"(1)\n" 219 " bl my_direct_func\n" 220 PPC_LL" 6, "__stringify(STACK_FRAME_ARG4)"(1)\n" 221 PPC_LL" 5, "__stringify(STACK_FRAME_ARG3)"(1)\n" 222 PPC_LL" 4, "__stringify(STACK_FRAME_ARG2)"(1)\n" 223 PPC_LL" 3, "__stringify(STACK_FRAME_ARG1)"(1)\n" 224 PPC64_TOC_RESTORE 225 " addi 1, 1, "__stringify(STACK_FRAME_SIZE)"\n" 226 PPC_FTRACE_RESTORE_LR 227 " addi 1, 1, "__stringify(STACK_FRAME_MIN_SIZE)"\n" 228 PPC_LL" 0, "__stringify(PPC_LR_STKOFF)"(1)\n" 229 PPC_FTRACE_RET 230 PPC64_TOC 231 " .size my_tramp, .-my_tramp\n" 232 " .popsection\n" 233 ); 234 235 #endif /* CONFIG_PPC */ 236 237 static struct ftrace_ops direct; 238 239 static int __init ftrace_direct_init(void) 240 { 241 ftrace_set_filter_ip(&direct, (unsigned long) handle_mm_fault, 0, 0); 242 243 return register_ftrace_direct(&direct, (unsigned long) my_tramp); 244 } 245 246 static void __exit ftrace_direct_exit(void) 247 { 248 unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true); 249 } 250 251 module_init(ftrace_direct_init); 252 module_exit(ftrace_direct_exit); 253 254 MODULE_AUTHOR("Steven Rostedt"); 255 MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()"); 256 MODULE_LICENSE("GPL"); 257