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 10extern void my_direct_func(struct vm_area_struct *vma, unsigned long address, 11 unsigned int flags, struct pt_regs *regs); 12 13void 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 20extern void my_tramp(void *); 21 22#ifdef CONFIG_RISCV 23#include <asm/asm.h> 24 25asm ( 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 55asm ( 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 83asm ( 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 107asm ( 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 131asm ( 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 156static struct ftrace_ops direct; 157 158static 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 165static void __exit ftrace_direct_exit(void) 166{ 167 unregister_ftrace_direct(&direct, (unsigned long)my_tramp, true); 168} 169 170module_init(ftrace_direct_init); 171module_exit(ftrace_direct_exit); 172 173MODULE_AUTHOR("Steven Rostedt"); 174MODULE_DESCRIPTION("Another example use case of using register_ftrace_direct()"); 175MODULE_LICENSE("GPL"); 176