[PATCH 07/17] trace doc: convert trace/uprobetracer.txt to rst format

From: changbin . du
Date: Sat Feb 17 2018 - 00:50:34 EST


From: Changbin Du <changbin.du@xxxxxxxxx>

This converts the plain text documentation to reStructuredText format and
add it into Sphinx TOC tree. No essential content change.

Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
---
Documentation/trace/index.rst | 1 +
.../trace/{uprobetracer.txt => uprobetracer.rst} | 44 +++++++++++++---------
2 files changed, 27 insertions(+), 18 deletions(-)
rename Documentation/trace/{uprobetracer.txt => uprobetracer.rst} (86%)

diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst
index c8e2130..353fb8a 100644
--- a/Documentation/trace/index.rst
+++ b/Documentation/trace/index.rst
@@ -10,3 +10,4 @@ Linux Tracing Technologies
ftrace
ftrace-uses
kprobetrace
+ uprobetracer
diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.rst
similarity index 86%
rename from Documentation/trace/uprobetracer.txt
rename to Documentation/trace/uprobetracer.rst
index bf526a7c..98d3f69 100644
--- a/Documentation/trace/uprobetracer.txt
+++ b/Documentation/trace/uprobetracer.rst
@@ -1,7 +1,8 @@
- Uprobe-tracer: Uprobe-based Event Tracing
- =========================================
+=========================================
+Uprobe-tracer: Uprobe-based Event Tracing
+=========================================

- Documentation written by Srikar Dronamraju
+:Author: Srikar Dronamraju


Overview
@@ -19,6 +20,8 @@ user to calculate the offset of the probepoint in the object.

Synopsis of uprobe_tracer
-------------------------
+::
+
p[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a uprobe
r[:[GRP/]EVENT] PATH:OFFSET [FETCHARGS] : Set a return uprobe (uretprobe)
-:[GRP/]EVENT : Clear uprobe or uretprobe event
@@ -57,7 +60,7 @@ x86-64 uses x64).
String type is a special type, which fetches a "null-terminated" string from
user space.
Bitfield is another special type, which takes 3 parameters, bit-width, bit-
-offset, and container-size (usually 32). The syntax is;
+offset, and container-size (usually 32). The syntax is::

b<bit-width>@<bit-offset>/<container-size>

@@ -74,28 +77,28 @@ the third is the number of probe miss-hits.
Usage examples
--------------
* Add a probe as a new uprobe event, write a new definition to uprobe_events
-as below: (sets a uprobe at an offset of 0x4245c0 in the executable /bin/bash)
+ as below (sets a uprobe at an offset of 0x4245c0 in the executable /bin/bash)::

echo 'p /bin/bash:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events

- * Add a probe as a new uretprobe event:
+ * Add a probe as a new uretprobe event::

echo 'r /bin/bash:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events

- * Unset registered event:
+ * Unset registered event::

echo '-:p_bash_0x4245c0' >> /sys/kernel/debug/tracing/uprobe_events

- * Print out the events that are registered:
+ * Print out the events that are registered::

cat /sys/kernel/debug/tracing/uprobe_events

- * Clear all events:
+ * Clear all events::

echo > /sys/kernel/debug/tracing/uprobe_events

Following example shows how to dump the instruction pointer and %ax register
-at the probed text address. Probe zfree function in /bin/zsh:
+at the probed text address. Probe zfree function in /bin/zsh::

# cd /sys/kernel/debug/tracing/
# cat /proc/`pgrep zsh`/maps | grep /bin/zsh | grep r-xp
@@ -103,24 +106,27 @@ at the probed text address. Probe zfree function in /bin/zsh:
# objdump -T /bin/zsh | grep -w zfree
0000000000446420 g DF .text 0000000000000012 Base zfree

- 0x46420 is the offset of zfree in object /bin/zsh that is loaded at
- 0x00400000. Hence the command to uprobe would be:
+0x46420 is the offset of zfree in object /bin/zsh that is loaded at
+0x00400000. Hence the command to uprobe would be::

# echo 'p:zfree_entry /bin/zsh:0x46420 %ip %ax' > uprobe_events

- And the same for the uretprobe would be:
+And the same for the uretprobe would be::

# echo 'r:zfree_exit /bin/zsh:0x46420 %ip %ax' >> uprobe_events

-Please note: User has to explicitly calculate the offset of the probe-point
-in the object. We can see the events that are registered by looking at the
-uprobe_events file.
+.. note:: User has to explicitly calculate the offset of the probe-point
+ in the object.
+
+We can see the events that are registered by looking at the uprobe_events file.
+::

# cat uprobe_events
p:uprobes/zfree_entry /bin/zsh:0x00046420 arg1=%ip arg2=%ax
r:uprobes/zfree_exit /bin/zsh:0x00046420 arg1=%ip arg2=%ax

-Format of events can be seen by viewing the file events/uprobes/zfree_entry/format
+Format of events can be seen by viewing the file events/uprobes/zfree_entry/format.
+::

# cat events/uprobes/zfree_entry/format
name: zfree_entry
@@ -139,16 +145,18 @@ Format of events can be seen by viewing the file events/uprobes/zfree_entry/form
print fmt: "(%lx) arg1=%lx arg2=%lx", REC->__probe_ip, REC->arg1, REC->arg2

Right after definition, each event is disabled by default. For tracing these
-events, you need to enable it by:
+events, you need to enable it by::

# echo 1 > events/uprobes/enable

Lets disable the event after sleeping for some time.
+::

# sleep 20
# echo 0 > events/uprobes/enable

And you can see the traced information via /sys/kernel/debug/tracing/trace.
+::

# cat trace
# tracer: nop
--
2.7.4