// SPDX-License-Identifier: GPL-2.0-only #include #include #include #ifndef CONFIG_ARM64 #include #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 #include 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");