2019-06-05 00:47:24

by Divya Indi

Subject: [RFC] Kernel Access to Ftrace instances.

Hi,
Please Review the patches that follow. These include -

[PATCH 1/3] tracing: Relevant changes for kernel access to Ftrace instances.
[PATCH 2/3] tracing: Adding additional NULL checks.
[PATCH 3/3] tracing: Add 2 new funcs. for kernel access to Ftrace instances.

Let me know if you have any concerns or questions.

A sample module demonstrating the use of the above functions will follow soon.

Thanks,
Divya

2019-06-05 00:47:49

by Divya Indi

Subject: [PATCH 1/3] tracing: Relevant changes for kernel access to Ftrace instances.

For commit (f45d122): tracing: Kernel access to Ftrace instances.
We need the following additional changes to ensure other kernel components can
use these functions -
1) Remove static keyword for newly exported fn - ftrace_set_clr_event.
2) Add the req functions to header file include/linux/trace_events.h.

Signed-off-by: Divya Indi <[email protected]>
---
include/linux/trace_events.h | 6 ++++++
kernel/trace/trace_events.c | 2 +-
2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 8a62731..d7b7d85 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -539,6 +539,12 @@ extern int trace_define_field(struct trace_event_call *call, const char *type,

#define is_signed_type(type) (((type)(-1)) < (type)1)

+void trace_printk_init_buffers(void);
+int trace_array_printk(struct trace_array *tr, unsigned long ip,
+ const char *fmt, ...);
+struct trace_array *trace_array_create(const char *name);
+int trace_array_destroy(struct trace_array *tr);
+int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
int trace_set_clr_event(const char *system, const char *event, int set);

/*
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 0ce3db6..b6b4618 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -795,7 +795,7 @@ static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
return ret;
}

-static int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
+int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
{
char *event = NULL, *sub = NULL, *match;
int ret;
--
1.8.3.1

2019-06-05 00:48:26

by Divya Indi

Subject: [PATCH 2/3] tracing: Adding additional NULL checks.

Now that we have exported certain functions providing access to Ftrace
instances from other kernel components, we are adding some additional
NULL checks to ensure safe usage by the users.

Signed-off-by: Divya Indi <[email protected]>
---
kernel/trace/trace.c | 3 +++
kernel/trace/trace_events.c | 2 ++
2 files changed, 5 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1c80521..a60dc13 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3205,6 +3205,9 @@ int trace_array_printk(struct trace_array *tr,
if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
return 0;

+ if (!tr)
+ return -EINVAL;
+
va_start(ap, fmt);
ret = trace_array_vprintk(tr, ip, fmt, ap);
va_end(ap);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index b6b4618..445b059 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -800,6 +800,8 @@ int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
char *event = NULL, *sub = NULL, *match;
int ret;

+ if (!tr)
+ return -ENODEV;
/*
* The buf format can be <subsystem>:<event-name>
* *:<event-name> means any event by that name.
--
1.8.3.1