From 00b27da349b8b6b891f8eafb3873ee82b77a61d8 Mon Sep 17 00:00:00 2001 From: Changbin Du Date: Sat, 17 Feb 2018 13:39:40 +0800 Subject: [PATCH] trace doc: convert trace/uprobetracer.txt to rst format This converts the plain text documentation to reStructuredText format and add it into Sphinx TOC tree. No essential content change. Cc: Steven Rostedt Signed-off-by: Changbin Du Signed-off-by: Jonathan Corbet --- Documentation/trace/index.rst | 1 + .../{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 c8e2130a7318..353fb8a91ab2 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 bf526a7c5559..98d3f692957a 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@/ @@ -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 -- GitLab