1228925Sgonzo// SPDX-License-Identifier: GPL-2.0-only 2228925Sgonzo#include <linux/module.h> 3228925Sgonzo#include <linux/kthread.h> 4228925Sgonzo#include <linux/ftrace.h> 5228925Sgonzo#ifndef CONFIG_ARM64 6228925Sgonzo#include <asm/asm-offsets.h> 7228925Sgonzo#endif 8228925Sgonzo 9228925Sgonzoextern void my_direct_func1(void); 10228925Sgonzoextern void my_direct_func2(void); 11228925Sgonzo 12228925Sgonzovoid my_direct_func1(void) 13228925Sgonzo{ 14228925Sgonzo trace_printk("my direct func1\n"); 15228925Sgonzo} 16228925Sgonzo 17228925Sgonzovoid my_direct_func2(void) 18228925Sgonzo{ 19228925Sgonzo trace_printk("my direct func2\n"); 20228925Sgonzo} 21228925Sgonzo 22228925Sgonzoextern void my_tramp1(void *); 23228925Sgonzoextern void my_tramp2(void *); 24228925Sgonzo 25228925Sgonzostatic unsigned long my_ip = (unsigned long)schedule; 26228925Sgonzo 27228925Sgonzo#ifdef CONFIG_RISCV 28228925Sgonzo#include <asm/asm.h> 29228925Sgonzo 30228925Sgonzoasm ( 31228925Sgonzo" .pushsection .text, \"ax\", @progbits\n" 32228925Sgonzo" .type my_tramp1, @function\n" 33228925Sgonzo" .globl my_tramp1\n" 34228925Sgonzo" my_tramp1:\n" 35228925Sgonzo" addi sp,sp,-2*"SZREG"\n" 36228925Sgonzo" "REG_S" t0,0*"SZREG"(sp)\n" 37228925Sgonzo" "REG_S" ra,1*"SZREG"(sp)\n" 38228925Sgonzo" call my_direct_func1\n" 39228925Sgonzo" "REG_L" t0,0*"SZREG"(sp)\n" 40228925Sgonzo" "REG_L" ra,1*"SZREG"(sp)\n" 41228925Sgonzo" addi sp,sp,2*"SZREG"\n" 42228925Sgonzo" jr t0\n" 43228925Sgonzo" .size my_tramp1, .-my_tramp1\n" 44228925Sgonzo" .type my_tramp2, @function\n" 45228925Sgonzo" .globl my_tramp2\n" 46228925Sgonzo 47228925Sgonzo" my_tramp2:\n" 48228925Sgonzo" addi sp,sp,-2*"SZREG"\n" 49228925Sgonzo" "REG_S" t0,0*"SZREG"(sp)\n" 50228925Sgonzo" "REG_S" ra,1*"SZREG"(sp)\n" 51232812Sjmallett" call my_direct_func2\n" 52228925Sgonzo" "REG_L" t0,0*"SZREG"(sp)\n" 53228925Sgonzo" "REG_L" ra,1*"SZREG"(sp)\n" 54277996Sloos" addi sp,sp,2*"SZREG"\n" 55228925Sgonzo" jr t0\n" 56228925Sgonzo" .size my_tramp2, .-my_tramp2\n" 57228925Sgonzo" .popsection\n" 58228925Sgonzo); 59228925Sgonzo 60228925Sgonzo#endif /* CONFIG_RISCV */ 61228925Sgonzo 62228925Sgonzo#ifdef CONFIG_X86_64 63228925Sgonzo 64228925Sgonzo#include <asm/ibt.h> 65228925Sgonzo#include <asm/nospec-branch.h> 66228925Sgonzo 67228925Sgonzoasm ( 68228925Sgonzo" .pushsection .text, \"ax\", @progbits\n" 69228925Sgonzo" .type my_tramp1, @function\n" 70228925Sgonzo" .globl my_tramp1\n" 71228925Sgonzo" my_tramp1:" 72228925Sgonzo ASM_ENDBR 73228925Sgonzo" pushq %rbp\n" 74228925Sgonzo" movq %rsp, %rbp\n" 75228925Sgonzo CALL_DEPTH_ACCOUNT 76228925Sgonzo" call my_direct_func1\n" 77228925Sgonzo" leave\n" 78228925Sgonzo" .size my_tramp1, .-my_tramp1\n" 79228925Sgonzo ASM_RET 80228925Sgonzo 81228925Sgonzo" .type my_tramp2, @function\n" 82228925Sgonzo" .globl my_tramp2\n" 83228925Sgonzo" my_tramp2:" 84228925Sgonzo ASM_ENDBR 85228925Sgonzo" pushq %rbp\n" 86228925Sgonzo" movq %rsp, %rbp\n" 87228925Sgonzo CALL_DEPTH_ACCOUNT 88228925Sgonzo" call my_direct_func2\n" 89228925Sgonzo" leave\n" 90228925Sgonzo ASM_RET 91228925Sgonzo" .size my_tramp2, .-my_tramp2\n" 92228925Sgonzo" .popsection\n" 93228925Sgonzo); 94277996Sloos 95228925Sgonzo#endif /* CONFIG_X86_64 */ 96228925Sgonzo 97228925Sgonzo#ifdef CONFIG_S390 98228925Sgonzo 99228925Sgonzoasm ( 100228925Sgonzo" .pushsection .text, \"ax\", @progbits\n" 101228925Sgonzo" .type my_tramp1, @function\n" 102228925Sgonzo" .globl my_tramp1\n" 103228925Sgonzo" my_tramp1:" 104228925Sgonzo" lgr %r1,%r15\n" 105228925Sgonzo" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 106228925Sgonzo" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 107228925Sgonzo" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" 108228925Sgonzo" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" 109228925Sgonzo" brasl %r14,my_direct_func1\n" 110228925Sgonzo" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" 111228925Sgonzo" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 112228925Sgonzo" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 113228925Sgonzo" lgr %r1,%r0\n" 114228925Sgonzo" br %r1\n" 115228925Sgonzo" .size my_tramp1, .-my_tramp1\n" 116228925Sgonzo" .type my_tramp2, @function\n" 117228925Sgonzo" .globl my_tramp2\n" 118228925Sgonzo" my_tramp2:" 119228925Sgonzo" lgr %r1,%r15\n" 120228925Sgonzo" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 121228925Sgonzo" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 122228925Sgonzo" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" 123228925Sgonzo" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" 124228925Sgonzo" brasl %r14,my_direct_func2\n" 125228925Sgonzo" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" 126228925Sgonzo" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 127228925Sgonzo" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 128228925Sgonzo" lgr %r1,%r0\n" 129228925Sgonzo" br %r1\n" 130228925Sgonzo" .size my_tramp2, .-my_tramp2\n" 131228925Sgonzo" .popsection\n" 132228925Sgonzo); 133228925Sgonzo 134228925Sgonzo#endif /* CONFIG_S390 */ 135228925Sgonzo 136228925Sgonzo#ifdef CONFIG_ARM64 137228925Sgonzo 138228925Sgonzoasm ( 139277996Sloos" .pushsection .text, \"ax\", @progbits\n" 140277996Sloos" .type my_tramp1, @function\n" 141277996Sloos" .globl my_tramp1\n" 142277996Sloos" my_tramp1:" 143277996Sloos" hint 34\n" // bti c 144277996Sloos" sub sp, sp, #16\n" 145277996Sloos" stp x9, x30, [sp]\n" 146277996Sloos" bl my_direct_func1\n" 147277996Sloos" ldp x30, x9, [sp]\n" 148277996Sloos" add sp, sp, #16\n" 149228925Sgonzo" ret x9\n" 150228925Sgonzo" .size my_tramp1, .-my_tramp1\n" 151228925Sgonzo 152228925Sgonzo" .type my_tramp2, @function\n" 153228925Sgonzo" .globl my_tramp2\n" 154228925Sgonzo" my_tramp2:" 155228925Sgonzo" hint 34\n" // bti c 156228925Sgonzo" sub sp, sp, #16\n" 157228925Sgonzo" stp x9, x30, [sp]\n" 158228925Sgonzo" bl my_direct_func2\n" 159228925Sgonzo" ldp x30, x9, [sp]\n" 160228925Sgonzo" add sp, sp, #16\n" 161228925Sgonzo" ret x9\n" 162228925Sgonzo" .size my_tramp2, .-my_tramp2\n" 163228925Sgonzo" .popsection\n" 164228925Sgonzo); 165228925Sgonzo 166228925Sgonzo#endif /* CONFIG_ARM64 */ 167228925Sgonzo 168228925Sgonzo#ifdef CONFIG_LOONGARCH 169228925Sgonzo 170228925Sgonzoasm ( 171228925Sgonzo" .pushsection .text, \"ax\", @progbits\n" 172228925Sgonzo" .type my_tramp1, @function\n" 173228925Sgonzo" .globl my_tramp1\n" 174228925Sgonzo" my_tramp1:\n" 175228925Sgonzo" addi.d $sp, $sp, -16\n" 176228925Sgonzo" st.d $t0, $sp, 0\n" 177228925Sgonzo" st.d $ra, $sp, 8\n" 178228925Sgonzo" bl my_direct_func1\n" 179228925Sgonzo" ld.d $t0, $sp, 0\n" 180228925Sgonzo" ld.d $ra, $sp, 8\n" 181228925Sgonzo" addi.d $sp, $sp, 16\n" 182228925Sgonzo" jr $t0\n" 183228925Sgonzo" .size my_tramp1, .-my_tramp1\n" 184228925Sgonzo 185228925Sgonzo" .type my_tramp2, @function\n" 186228925Sgonzo" .globl my_tramp2\n" 187228925Sgonzo" my_tramp2:\n" 188228925Sgonzo" addi.d $sp, $sp, -16\n" 189228925Sgonzo" st.d $t0, $sp, 0\n" 190228925Sgonzo" st.d $ra, $sp, 8\n" 191228925Sgonzo" bl my_direct_func2\n" 192228925Sgonzo" ld.d $t0, $sp, 0\n" 193228925Sgonzo" ld.d $ra, $sp, 8\n" 194228925Sgonzo" addi.d $sp, $sp, 16\n" 195228925Sgonzo" jr $t0\n" 196228925Sgonzo" .size my_tramp2, .-my_tramp2\n" 197228925Sgonzo" .popsection\n" 198228925Sgonzo); 199228925Sgonzo 200228925Sgonzo#endif /* CONFIG_LOONGARCH */ 201228925Sgonzo 202228925Sgonzostatic struct ftrace_ops direct; 203228925Sgonzo 204228925Sgonzostatic unsigned long my_tramp = (unsigned long)my_tramp1; 205228925Sgonzostatic unsigned long tramps[2] = { 206228925Sgonzo (unsigned long)my_tramp1, 207228925Sgonzo (unsigned long)my_tramp2, 208228925Sgonzo}; 209228925Sgonzo 210228925Sgonzostatic int simple_thread(void *arg) 211228925Sgonzo{ 212228925Sgonzo static int t; 213228925Sgonzo int ret = 0; 214228925Sgonzo 215228925Sgonzo while (!kthread_should_stop()) { 216228925Sgonzo set_current_state(TASK_INTERRUPTIBLE); 217228925Sgonzo schedule_timeout(2 * HZ); 218228925Sgonzo 219228925Sgonzo if (ret) 220228925Sgonzo continue; 221228925Sgonzo t ^= 1; 222228925Sgonzo ret = modify_ftrace_direct(&direct, tramps[t]); 223228925Sgonzo if (!ret) 224228925Sgonzo my_tramp = tramps[t]; 225228925Sgonzo WARN_ON_ONCE(ret); 226228925Sgonzo } 227228925Sgonzo 228228925Sgonzo return 0; 229228925Sgonzo} 230228925Sgonzo 231228925Sgonzostatic struct task_struct *simple_tsk; 232228925Sgonzo 233228925Sgonzostatic int __init ftrace_direct_init(void) 234274670Sloos{ 235228925Sgonzo int ret; 236228925Sgonzo 237228925Sgonzo ftrace_set_filter_ip(&direct, (unsigned long) my_ip, 0, 0); 238228925Sgonzo ret = register_ftrace_direct(&direct, my_tramp); 239228925Sgonzo 240228925Sgonzo if (!ret) 241228925Sgonzo simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); 242228925Sgonzo return ret; 243228925Sgonzo} 244228925Sgonzo 245228925Sgonzostatic void __exit ftrace_direct_exit(void) 246228925Sgonzo{ 247228925Sgonzo kthread_stop(simple_tsk); 248228925Sgonzo unregister_ftrace_direct(&direct, my_tramp, true); 249228925Sgonzo} 250228925Sgonzo 251228925Sgonzomodule_init(ftrace_direct_init); 252228925Sgonzomodule_exit(ftrace_direct_exit); 253228925Sgonzo 254228925SgonzoMODULE_AUTHOR("Steven Rostedt"); 255228925SgonzoMODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()"); 256228925SgonzoMODULE_LICENSE("GPL"); 257228925Sgonzo