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-rw-r--r--Documentation/trace/events.txt11
-rw-r--r--Documentation/trace/ftrace.txt52
-rw-r--r--Documentation/trace/kprobetrace.txt4
3 files changed, 58 insertions, 9 deletions
diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
index 02ac6ed38b2d..09bd8e902989 100644
--- a/Documentation/trace/events.txt
+++ b/Documentation/trace/events.txt
@@ -90,7 +90,8 @@ In order to facilitate early boot debugging, use boot option:
trace_event=[event-list]
-The format of this boot option is the same as described in section 2.1.
+event-list is a comma separated list of events. See section 2.1 for event
+format.
3. Defining an event-enabled tracepoint
=======================================
@@ -238,7 +239,7 @@ subsystem's filter file.
For convenience, filters for every event in a subsystem can be set or
cleared as a group by writing a filter expression into the filter file
-at the root of the subsytem. Note however, that if a filter for any
+at the root of the subsystem. Note however, that if a filter for any
event within the subsystem lacks a field specified in the subsystem
filter, or if the filter can't be applied for any other reason, the
filter for that event will retain its previous setting. This can
@@ -250,7 +251,7 @@ fields can be guaranteed to propagate successfully to all events.
Here are a few subsystem filter examples that also illustrate the
above points:
-Clear the filters on all events in the sched subsytem:
+Clear the filters on all events in the sched subsystem:
# cd /sys/kernel/debug/tracing/events/sched
# echo 0 > filter
@@ -260,7 +261,7 @@ none
none
Set a filter using only common fields for all events in the sched
-subsytem (all events end up with the same filter):
+subsystem (all events end up with the same filter):
# cd /sys/kernel/debug/tracing/events/sched
# echo common_pid == 0 > filter
@@ -270,7 +271,7 @@ common_pid == 0
common_pid == 0
Attempt to set a filter using a non-common field for all events in the
-sched subsytem (all events but those that have a prev_pid field retain
+sched subsystem (all events but those that have a prev_pid field retain
their old filters):
# cd /sys/kernel/debug/tracing/events/sched
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index bab3040da548..557c1edeccaf 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -155,6 +155,9 @@ of ftrace. Here is a list of some of the key files:
to be traced. Echoing names of functions into this file
will limit the trace to only those functions.
+ This interface also allows for commands to be used. See the
+ "Filter commands" section for more details.
+
set_ftrace_notrace:
This has an effect opposite to that of
@@ -1337,12 +1340,14 @@ ftrace_dump_on_oops must be set. To set ftrace_dump_on_oops, one
can either use the sysctl function or set it via the proc system
interface.
- sysctl kernel.ftrace_dump_on_oops=1
+ sysctl kernel.ftrace_dump_on_oops=n
or
- echo 1 > /proc/sys/kernel/ftrace_dump_on_oops
+ echo n > /proc/sys/kernel/ftrace_dump_on_oops
+If n = 1, ftrace will dump buffers of all CPUs, if n = 2 ftrace will
+only dump the buffer of the CPU that triggered the oops.
Here's an example of such a dump after a null pointer
dereference in a kernel module:
@@ -1588,7 +1593,7 @@ module author does not need to worry about it.
When tracing is enabled, kstop_machine is called to prevent
races with the CPUS executing code being modified (which can
-cause the CPU to do undesireable things), and the nops are
+cause the CPU to do undesirable things), and the nops are
patched back to calls. But this time, they do not call mcount
(which is just a function stub). They now call into the ftrace
infrastructure.
@@ -1822,6 +1827,47 @@ this special filter via:
echo > set_graph_function
+Filter commands
+---------------
+
+A few commands are supported by the set_ftrace_filter interface.
+Trace commands have the following format:
+
+<function>:<command>:<parameter>
+
+The following commands are supported:
+
+- mod
+ This command enables function filtering per module. The
+ parameter defines the module. For example, if only the write*
+ functions in the ext3 module are desired, run:
+
+ echo 'write*:mod:ext3' > set_ftrace_filter
+
+ This command interacts with the filter in the same way as
+ filtering based on function names. Thus, adding more functions
+ in a different module is accomplished by appending (>>) to the
+ filter file. Remove specific module functions by prepending
+ '!':
+
+ echo '!writeback*:mod:ext3' >> set_ftrace_filter
+
+- traceon/traceoff
+ These commands turn tracing on and off when the specified
+ functions are hit. The parameter determines how many times the
+ tracing system is turned on and off. If unspecified, there is
+ no limit. For example, to disable tracing when a schedule bug
+ is hit the first 5 times, run:
+
+ echo '__schedule_bug:traceoff:5' > set_ftrace_filter
+
+ These commands are cumulative whether or not they are appended
+ to set_ftrace_filter. To remove a command, prepend it by '!'
+ and drop the parameter:
+
+ echo '!__schedule_bug:traceoff' > set_ftrace_filter
+
+
trace_pipe
----------
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
index a9100b28eb84..ec94748ae65b 100644
--- a/Documentation/trace/kprobetrace.txt
+++ b/Documentation/trace/kprobetrace.txt
@@ -40,7 +40,9 @@ Synopsis of kprobe_events
$stack : Fetch stack address.
$retval : Fetch return value.(*)
+|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
- NAME=FETCHARG: Set NAME as the argument name of FETCHARG.
+ NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
+ FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
+ (u8/u16/u32/u64/s8/s16/s32/s64) are supported.
(*) only for return probe.
(**) this is useful for fetching a field of data structures.