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