diff options
| -rw-r--r-- | samples/Kconfig | 8 | ||||
| -rw-r--r-- | samples/Makefile | 1 | ||||
| -rw-r--r-- | samples/ftrace/Makefile | 3 | ||||
| -rw-r--r-- | samples/ftrace/ftrace-direct.c | 45 |
4 files changed, 57 insertions, 0 deletions
diff --git a/samples/Kconfig b/samples/Kconfig index c8dacb4dda80..65b5967dac0c 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -19,6 +19,14 @@ config SAMPLE_TRACE_PRINTK This builds a module that calls trace_printk() and can be used to test various trace_printk() calls from a module. +config SAMPLE_FTRACE_DIRECT + tristate "Build register_ftrace_direct() example" + depends on DYNAMIC_FTRACE_WITH_DIRECT_CALLS && m + depends on X86_64 # has x86_64 inlined asm + help + This builds an ftrace direct function example + that hooks to wake_up_process and prints the parameters. + config SAMPLE_KOBJECT tristate "Build kobject examples" help diff --git a/samples/Makefile b/samples/Makefile index 7d6e4ca28d69..cd496d633370 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -17,6 +17,7 @@ obj-$(CONFIG_SAMPLE_RPMSG_CLIENT) += rpmsg/ subdir-$(CONFIG_SAMPLE_SECCOMP) += seccomp obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace_events/ obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace_printk/ +obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace/ obj-$(CONFIG_VIDEO_PCI_SKELETON) += v4l/ obj-y += vfio-mdev/ subdir-$(CONFIG_SAMPLE_VFS) += vfs diff --git a/samples/ftrace/Makefile b/samples/ftrace/Makefile new file mode 100644 index 000000000000..3718ab39eba3 --- /dev/null +++ b/samples/ftrace/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0-only + +obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct.o diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c new file mode 100644 index 000000000000..1483f067b000 --- /dev/null +++ b/samples/ftrace/ftrace-direct.c @@ -0,0 +1,45 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include <linux/module.h> + +#include <linux/sched.h> /* for wake_up_process() */ +#include <linux/ftrace.h> + +void my_direct_func(struct task_struct *p) +{ + trace_printk("wakeing up %s-%d\n", p->comm, p->pid); +} + +extern void my_tramp(void *); + +asm ( +" .pushsection .text, \"ax\", @progbits\n" +" my_tramp:" +" pushq %rbp\n" +" movq %rsp, %rbp\n" +" pushq %rdi\n" +" call my_direct_func\n" +" popq %rdi\n" +" leave\n" +" ret\n" +" .popsection\n" +); + + +static int __init ftrace_direct_init(void) +{ + return register_ftrace_direct((unsigned long)wake_up_process, + (unsigned long)my_tramp); +} + +static void __exit ftrace_direct_exit(void) +{ + unregister_ftrace_direct((unsigned long)wake_up_process, + (unsigned long)my_tramp); +} + +module_init(ftrace_direct_init); +module_exit(ftrace_direct_exit); + +MODULE_AUTHOR("Steven Rostedt"); +MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()"); +MODULE_LICENSE("GPL"); |