[PATCH 08/19] ftrace/samples: Add multi direct interface test module

Jiri Olsa
2021-06-05T11:11:13Z

Adding simple module that uses multi direct interface:

register_ftrace_direct_multi
unregister_ftrace_direct_multi

The init function registers trampoline for 2 functions,
and exit function unregisters them.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
samples/ftrace/Makefile | 1 +
samples/ftrace/ftrace-direct-multi.c | 52 ++++++++++++++++++++++++++++
2 files changed, 53 insertions(+)
create mode 100644 samples/ftrace/ftrace-direct-multi.c

diff --git a/samples/ftrace/Makefile b/samples/ftrace/Makefile
index 4ce896e10b2e..ab1d1c05c288 100644
--- a/samples/ftrace/Makefile
+++ b/samples/ftrace/Makefile
@@ -3,6 +3,7 @@
obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct.o
obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-too.o
obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-modify.o
+obj-$(CONFIG_SAMPLE_FTRACE_DIRECT) += ftrace-direct-multi.o

CFLAGS_sample-trace-array.o := -I$(src)
obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += sample-trace-array.o
diff --git a/samples/ftrace/ftrace-direct-multi.c b/samples/ftrace/ftrace-direct-multi.c
new file mode 100644
index 000000000000..76b34d46d11c
--- /dev/null
+++ b/samples/ftrace/ftrace-direct-multi.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+
+#include <linux/mm.h> /* for handle_mm_fault() */
+#include <linux/ftrace.h>
+#include <linux/sched/stat.h>
+
+void my_direct_func(unsigned long ip)
+{
+ trace_printk("ip %lx\n", ip);
+}
+
+extern void my_tramp(void *);
+
+asm (
+" .pushsection .text, \"ax\", @progbits\n"
+" .type my_tramp, @function\n"
+" .globl my_tramp\n"
+" my_tramp:"
+" pushq %rbp\n"
+" movq %rsp, %rbp\n"
+" pushq %rdi\n"
+" movq 8(%rbp), %rdi\n"
+" call my_direct_func\n"
+" popq %rdi\n"
+" leave\n"
+" ret\n"
+" .size my_tramp, .-my_tramp\n"
+" .popsection\n"
+);
+
+static struct ftrace_ops direct;
+
+static int __init ftrace_direct_multi_init(void)
+{
+ ftrace_set_filter_ip(&direct, (unsigned long) wake_up_process, 0, 0);
+ ftrace_set_filter_ip(&direct, (unsigned long) schedule, 0, 0);
+
+ return register_ftrace_direct_multi(&direct, (unsigned long) my_tramp);
+}
+
+static void __exit ftrace_direct_multi_exit(void)
+{
+ unregister_ftrace_direct_multi(&direct);
+}
+
+module_init(ftrace_direct_multi_init);
+module_exit(ftrace_direct_multi_exit);
+
+MODULE_AUTHOR("Jiri Olsa");
+MODULE_DESCRIPTION("Example use case of using register_ftrace_direct_multi()");
+MODULE_LICENSE("GPL");
--
2.31.1