ftrace-direct-multi-modify.c (4151B)
1// SPDX-License-Identifier: GPL-2.0-only 2#include <linux/module.h> 3#include <linux/kthread.h> 4#include <linux/ftrace.h> 5#include <asm/asm-offsets.h> 6 7extern void my_direct_func1(unsigned long ip); 8extern void my_direct_func2(unsigned long ip); 9 10void my_direct_func1(unsigned long ip) 11{ 12 trace_printk("my direct func1 ip %lx\n", ip); 13} 14 15void my_direct_func2(unsigned long ip) 16{ 17 trace_printk("my direct func2 ip %lx\n", ip); 18} 19 20extern void my_tramp1(void *); 21extern void my_tramp2(void *); 22 23#ifdef CONFIG_X86_64 24 25#include <asm/ibt.h> 26 27asm ( 28" .pushsection .text, \"ax\", @progbits\n" 29" .type my_tramp1, @function\n" 30" .globl my_tramp1\n" 31" my_tramp1:" 32 ASM_ENDBR 33" pushq %rbp\n" 34" movq %rsp, %rbp\n" 35" pushq %rdi\n" 36" movq 8(%rbp), %rdi\n" 37" call my_direct_func1\n" 38" popq %rdi\n" 39" leave\n" 40 ASM_RET 41" .size my_tramp1, .-my_tramp1\n" 42 43" .type my_tramp2, @function\n" 44" .globl my_tramp2\n" 45" my_tramp2:" 46 ASM_ENDBR 47" pushq %rbp\n" 48" movq %rsp, %rbp\n" 49" pushq %rdi\n" 50" movq 8(%rbp), %rdi\n" 51" call my_direct_func2\n" 52" popq %rdi\n" 53" leave\n" 54 ASM_RET 55" .size my_tramp2, .-my_tramp2\n" 56" .popsection\n" 57); 58 59#endif /* CONFIG_X86_64 */ 60 61#ifdef CONFIG_S390 62 63asm ( 64" .pushsection .text, \"ax\", @progbits\n" 65" .type my_tramp1, @function\n" 66" .globl my_tramp1\n" 67" my_tramp1:" 68" lgr %r1,%r15\n" 69" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 70" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 71" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" 72" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" 73" lgr %r2,%r0\n" 74" brasl %r14,my_direct_func1\n" 75" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" 76" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 77" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 78" lgr %r1,%r0\n" 79" br %r1\n" 80" .size my_tramp1, .-my_tramp1\n" 81"\n" 82" .type my_tramp2, @function\n" 83" .globl my_tramp2\n" 84" my_tramp2:" 85" lgr %r1,%r15\n" 86" stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 87" stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 88" aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" 89" stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" 90" lgr %r2,%r0\n" 91" brasl %r14,my_direct_func2\n" 92" aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" 93" lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 94" lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 95" lgr %r1,%r0\n" 96" br %r1\n" 97" .size my_tramp2, .-my_tramp2\n" 98" .popsection\n" 99); 100 101#endif /* CONFIG_S390 */ 102 103static unsigned long my_tramp = (unsigned long)my_tramp1; 104static unsigned long tramps[2] = { 105 (unsigned long)my_tramp1, 106 (unsigned long)my_tramp2, 107}; 108 109static struct ftrace_ops direct; 110 111static int simple_thread(void *arg) 112{ 113 static int t; 114 int ret = 0; 115 116 while (!kthread_should_stop()) { 117 set_current_state(TASK_INTERRUPTIBLE); 118 schedule_timeout(2 * HZ); 119 120 if (ret) 121 continue; 122 t ^= 1; 123 ret = modify_ftrace_direct_multi(&direct, tramps[t]); 124 if (!ret) 125 my_tramp = tramps[t]; 126 WARN_ON_ONCE(ret); 127 } 128 129 return 0; 130} 131 132static struct task_struct *simple_tsk; 133 134static int __init ftrace_direct_multi_init(void) 135{ 136 int ret; 137 138 ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0); 139 ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0); 140 141 ret = register_ftrace_direct_multi(&direct, my_tramp); 142 143 if (!ret) 144 simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); 145 return ret; 146} 147 148static void __exit ftrace_direct_multi_exit(void) 149{ 150 kthread_stop(simple_tsk); 151 unregister_ftrace_direct_multi(&direct, my_tramp); 152} 153 154module_init(ftrace_direct_multi_init); 155module_exit(ftrace_direct_multi_exit); 156 157MODULE_AUTHOR("Jiri Olsa"); 158MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct_multi()"); 159MODULE_LICENSE("GPL");