1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/module.h> 3 #include <linux/kthread.h> 4 #include <linux/ftrace.h> 5 #ifndef CONFIG_ARM64 6 #include <asm/asm-offsets.h> 7 #endif 8 9 extern void my_direct_func1(unsigned long ip); 10 extern void my_direct_func2(unsigned long ip); 11 12 void my_direct_func1(unsigned long ip) 13 { 14 trace_printk("my direct func1 ip %lx\n", ip); 15 } 16 17 void my_direct_func2(unsigned long ip) 18 { 19 trace_printk("my direct func2 ip %lx\n", ip); 20 } 21 22 extern void my_tramp1(void *); 23 extern void my_tramp2(void *); 24 25 #ifdef CONFIG_X86_64 26 27 #include <asm/ibt.h> 28 #include <asm/nospec-branch.h> 29 30 asm ( 31 " .pushsection .text, \"ax\", @progbits\n" 32 " .type my_tramp1, @function\n" 33 " .globl my_tramp1\n" 34 " my_tramp1:" 35 ASM_ENDBR 36 " pushq %rbp\n" 37 " movq %rsp, %rbp\n" 38 CALL_DEPTH_ACCOUNT 39 " pushq %rdi\n" 40 " movq 8(%rbp), %rdi\n" 41 " call my_direct_func1\n" 42 " popq %rdi\n" 43 " leave\n" 44 ASM_RET 45 " .size my_tramp1, .-my_tramp1\n" 46 47 " .type my_tramp2, @function\n" 48 " .globl my_tramp2\n" 49 " my_tramp2:" 50 ASM_ENDBR 51 " pushq %rbp\n" 52 " movq %rsp, %rbp\n" 53 CALL_DEPTH_ACCOUNT 54 " pushq %rdi\n" 55 " movq 8(%rbp), %rdi\n" 56 " call my_direct_func2\n" 57 " popq %rdi\n" 58 " leave\n" 59 ASM_RET 60 " .size my_tramp2, .-my_tramp2\n" 61 " .popsection\n" 62 ); 63 64 #endif /* CONFIG_X86_64 */ 65 66 #ifdef CONFIG_S390 67 68 asm ( 69 " .pushsection .text, \"ax\", @progbits\n" 70 " .type my_tramp1, @function\n" 71 " .globl my_tramp1\n" 72 " my_tramp1:" 73 " lgr %r1,%r15\n" 74 " stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 75 " stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 76 " aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" 77 " stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" 78 " lgr %r2,%r0\n" 79 " brasl %r14,my_direct_func1\n" 80 " aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" 81 " lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 82 " lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 83 " lgr %r1,%r0\n" 84 " br %r1\n" 85 " .size my_tramp1, .-my_tramp1\n" 86 "\n" 87 " .type my_tramp2, @function\n" 88 " .globl my_tramp2\n" 89 " my_tramp2:" 90 " lgr %r1,%r15\n" 91 " stmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 92 " stg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 93 " aghi %r15,"__stringify(-STACK_FRAME_OVERHEAD)"\n" 94 " stg %r1,"__stringify(__SF_BACKCHAIN)"(%r15)\n" 95 " lgr %r2,%r0\n" 96 " brasl %r14,my_direct_func2\n" 97 " aghi %r15,"__stringify(STACK_FRAME_OVERHEAD)"\n" 98 " lmg %r0,%r5,"__stringify(__SF_GPRS)"(%r15)\n" 99 " lg %r14,"__stringify(__SF_GPRS+8*8)"(%r15)\n" 100 " lgr %r1,%r0\n" 101 " br %r1\n" 102 " .size my_tramp2, .-my_tramp2\n" 103 " .popsection\n" 104 ); 105 106 #endif /* CONFIG_S390 */ 107 108 #ifdef CONFIG_ARM64 109 110 asm ( 111 " .pushsection .text, \"ax\", @progbits\n" 112 " .type my_tramp1, @function\n" 113 " .globl my_tramp1\n" 114 " my_tramp1:" 115 " hint 34\n" // bti c 116 " sub sp, sp, #32\n" 117 " stp x9, x30, [sp]\n" 118 " str x0, [sp, #16]\n" 119 " mov x0, x30\n" 120 " bl my_direct_func1\n" 121 " ldp x30, x9, [sp]\n" 122 " ldr x0, [sp, #16]\n" 123 " add sp, sp, #32\n" 124 " ret x9\n" 125 " .size my_tramp1, .-my_tramp1\n" 126 127 " .type my_tramp2, @function\n" 128 " .globl my_tramp2\n" 129 " my_tramp2:" 130 " hint 34\n" // bti c 131 " sub sp, sp, #32\n" 132 " stp x9, x30, [sp]\n" 133 " str x0, [sp, #16]\n" 134 " mov x0, x30\n" 135 " bl my_direct_func2\n" 136 " ldp x30, x9, [sp]\n" 137 " ldr x0, [sp, #16]\n" 138 " add sp, sp, #32\n" 139 " ret x9\n" 140 " .size my_tramp2, .-my_tramp2\n" 141 " .popsection\n" 142 ); 143 144 #endif /* CONFIG_ARM64 */ 145 146 #ifdef CONFIG_LOONGARCH 147 #include <asm/asm.h> 148 149 asm ( 150 " .pushsection .text, \"ax\", @progbits\n" 151 " .type my_tramp1, @function\n" 152 " .globl my_tramp1\n" 153 " my_tramp1:\n" 154 " addi.d $sp, $sp, -32\n" 155 " st.d $a0, $sp, 0\n" 156 " st.d $t0, $sp, 8\n" 157 " st.d $ra, $sp, 16\n" 158 " move $a0, $t0\n" 159 " bl my_direct_func1\n" 160 " ld.d $a0, $sp, 0\n" 161 " ld.d $t0, $sp, 8\n" 162 " ld.d $ra, $sp, 16\n" 163 " addi.d $sp, $sp, 32\n" 164 " jr $t0\n" 165 " .size my_tramp1, .-my_tramp1\n" 166 167 " .type my_tramp2, @function\n" 168 " .globl my_tramp2\n" 169 " my_tramp2:\n" 170 " addi.d $sp, $sp, -32\n" 171 " st.d $a0, $sp, 0\n" 172 " st.d $t0, $sp, 8\n" 173 " st.d $ra, $sp, 16\n" 174 " move $a0, $t0\n" 175 " bl my_direct_func2\n" 176 " ld.d $a0, $sp, 0\n" 177 " ld.d $t0, $sp, 8\n" 178 " ld.d $ra, $sp, 16\n" 179 " addi.d $sp, $sp, 32\n" 180 " jr $t0\n" 181 " .size my_tramp2, .-my_tramp2\n" 182 " .popsection\n" 183 ); 184 185 #endif /* CONFIG_LOONGARCH */ 186 187 static unsigned long my_tramp = (unsigned long)my_tramp1; 188 static unsigned long tramps[2] = { 189 (unsigned long)my_tramp1, 190 (unsigned long)my_tramp2, 191 }; 192 193 static struct ftrace_ops direct; 194 195 static int simple_thread(void *arg) 196 { 197 static int t; 198 int ret = 0; 199 200 while (!kthread_should_stop()) { 201 set_current_state(TASK_INTERRUPTIBLE); 202 schedule_timeout(2 * HZ); 203 204 if (ret) 205 continue; 206 t ^= 1; 207 ret = modify_ftrace_direct(&direct, tramps[t]); 208 if (!ret) 209 my_tramp = tramps[t]; 210 WARN_ON_ONCE(ret); 211 } 212 213 return 0; 214 } 215 216 static struct task_struct *simple_tsk; 217 218 static int __init ftrace_direct_multi_init(void) 219 { 220 int ret; 221 222 ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0); 223 ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0); 224 225 ret = register_ftrace_direct(&direct, my_tramp); 226 227 if (!ret) 228 simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); 229 return ret; 230 } 231 232 static void __exit ftrace_direct_multi_exit(void) 233 { 234 kthread_stop(simple_tsk); 235 unregister_ftrace_direct(&direct, my_tramp, true); 236 } 237 238 module_init(ftrace_direct_multi_init); 239 module_exit(ftrace_direct_multi_exit); 240 241 MODULE_AUTHOR("Jiri Olsa"); 242 MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()"); 243 MODULE_LICENSE("GPL"); 244