Red Hat ENTERPRISE LINUX 5.4 - SYSTEMTAP TAPSET Reference Manual

Red Hat Enterprise

Linux 5.4

SystemTap

Tapset Reference

For SystemTap in Red Hat Enterprise Linux 5

William Cohen

Don Domingo

SystemTap Tapset Reference

Red Hat Enterprise Linux 5.4 SystemTap Tapset Reference
For SystemTap in Red Hat Enterprise Linux 5
Edition 1.0

Author William Cohen [e-mail]
Author Don Domingo [e-mail]

This documentation is free software; you can redistribute it and/or modify it under the terms of the
GNU General Public License version 2 as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not,
write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA

For more details see the file COPYING in the source distribution of Linux.

The Tapset Reference Guide describes the most common tapset definitions users can apply to
SystemTap scripts. All included tapsets documented in this guide are current as of Fedora 10 and the
latest upstream version of SystemTap.

iii

Preface vii

1. Document Conventions .................................................................................................. vii

1.1. Typographic Conventions .................................................................................... vii

1.2. Pull-quote Conventions ....................................................................................... viii

1.3. Notes and Warnings ............................................................................................ ix

2. We Need Feedback! ....................................................................................................... x

1. Introduction 1

1.1. Documentation Goals ................................................................................................... 1

2. Tapset Development Guidelines 3

2.1. Writing Good Tapsets ................................................................................................... 3

2.2. Elements of a Tapset ................................................................................................... 4

2.2.1. Tapset Files ...................................................................................................... 4

2.2.2. Namespace ....................................................................................................... 4

2.2.3. Comments and Documentation .......................................................................... 5

3. Context Functions 7

print_regs ........................................................................................................................... 7

execname ........................................................................................................................... 7

pid ...................................................................................................................................... 7

tid ....................................................................................................................................... 7

ppid .................................................................................................................................... 8

pgrp ................................................................................................................................... 8

sid ...................................................................................................................................... 8

pexecname ......................................................................................................................... 9

gid ...................................................................................................................................... 9

egid .................................................................................................................................... 9

uid ...................................................................................................................................... 9

euid .................................................................................................................................. 10

cpu ................................................................................................................................... 10

pp ..................................................................................................................................... 10

registers_valid ................................................................................................................... 11

user_mode ........................................................................................................................ 11

is_return ........................................................................................................................... 11

target ................................................................................................................................ 12

stack_size ......................................................................................................................... 12

stack_used ....................................................................................................................... 12

stack_unused .................................................................................................................... 13

uaddr ................................................................................................................................ 13

print_stack ........................................................................................................................ 14

probefunc ......................................................................................................................... 14

probemod ......................................................................................................................... 14

modname ......................................................................................................................... 15

symname .......................................................................................................................... 15

symdata ............................................................................................................................ 15

usymname ........................................................................................................................ 16

usymdata .......................................................................................................................... 16

print_ustack ...................................................................................................................... 17

print_backtrace .................................................................................................................. 17

backtrace .......................................................................................................................... 17

caller ................................................................................................................................ 18

caller_addr ........................................................................................................................ 18

SystemTap Tapset Reference

iv

print_ubacktrace ................................................................................................................ 19

ubacktrace ........................................................................................................................ 19

4. Timestamp Functions 21

get_cycles ......................................................................................................................... 21

5. Memory Tapset 23

vm_fault_contains .............................................................................................................. 23

vm.pagefault ..................................................................................................................... 23

vm.pagefault.return ............................................................................................................ 23

addr_to_node .................................................................................................................... 24

vm.write_shared ................................................................................................................ 24

vm.write_shared_copy ....................................................................................................... 25

vm.mmap .......................................................................................................................... 25

vm.munmap ...................................................................................................................... 25

vm.brk .............................................................................................................................. 26

vm.oom_kill ....................................................................................................................... 26

6. IO Scheduler Tapset 29

ioscheduler.elv_next_request ............................................................................................. 29

ioscheduler.elv_next_request.return .................................................................................... 29

ioscheduler.elv_add_request .............................................................................................. 29

ioscheduler.elv_completed_request .................................................................................... 30

7. SCSI Tapset 31

scsi.ioentry ........................................................................................................................ 31

scsi.iodispatching .............................................................................................................. 31

scsi.iodone ........................................................................................................................ 32

scsi.iocompleted ................................................................................................................ 32

8. Networking Tapset 35

netdev.receive ................................................................................................................... 35

netdev.transmit .................................................................................................................. 35

tcp.sendmsg ..................................................................................................................... 36

tcp.sendmsg.return ............................................................................................................ 36

tcp.recvmsg ...................................................................................................................... 36

tcp.recvmsg.return ............................................................................................................. 37

tcp.disconnect ................................................................................................................... 38

tcp.disconnect.return ......................................................................................................... 38

tcp.setsockopt ................................................................................................................... 39

tcp.setsockopt.return ......................................................................................................... 40

tcp.receive ........................................................................................................................ 40

udp.sendmsg .................................................................................................................... 41

udp.sendmsg.return ........................................................................................................... 41

udp.recvmsg ..................................................................................................................... 42

udp.recvmsg.return ............................................................................................................ 42

udp.disconnect .................................................................................................................. 43

udp.disconnect.return ........................................................................................................ 43

ip_ntop ............................................................................................................................. 44

9. Socket Tapset 45

socket.send ....................................................................................................................... 45

socket.receive ................................................................................................................... 45

socket.sendmsg ................................................................................................................ 46

v

socket.sendmsg.return ....................................................................................................... 47

socket.recvmsg ................................................................................................................. 48

socket.recvmsg.return ........................................................................................................ 49

socket.aio_write ................................................................................................................ 49

socket.aio_write.return ....................................................................................................... 50

socket.aio_read ................................................................................................................. 51

socket.aio_read.return ....................................................................................................... 52

socket.writev ..................................................................................................................... 53

socket.writev.return ............................................................................................................ 53

socket.readv ..................................................................................................................... 54

socket.readv.return ............................................................................................................ 55

socket.create ..................................................................................................................... 56

socket.create.return ........................................................................................................... 57

socket.close ...................................................................................................................... 57

socket.close.return ............................................................................................................ 58

sock_prot_num2str ............................................................................................................ 59

sock_prot_str2num ............................................................................................................ 59

sock_fam_num2str ............................................................................................................ 59

sock_fam_str2num ............................................................................................................ 59

sock_state_num2str ........................................................................................................... 60

sock_state_str2num ........................................................................................................... 60

10. Kernel Process Tapset 61

kprocess.create ................................................................................................................. 61

kprocess.start .................................................................................................................... 61

kprocess.exec ................................................................................................................... 62

kprocess.exec_complete .................................................................................................... 62

kprocess.exit ..................................................................................................................... 62

kprocess.release ............................................................................................................... 63

11. Signal Tapset 65

signal.send ....................................................................................................................... 65

signal.send.return .............................................................................................................. 66

signal.checkperm .............................................................................................................. 66

signal.checkperm.return ..................................................................................................... 67

signal.wakeup ................................................................................................................... 67

signal.check_ignored ......................................................................................................... 68

signal.check_ignored.return ................................................................................................ 68

signal.force_segv .............................................................................................................. 69

signal.force_segv.return ..................................................................................................... 69

signal.syskill ...................................................................................................................... 70

signal.syskill.return ............................................................................................................ 70

signal.sys_tkill ................................................................................................................... 70

signal.systkill.return ........................................................................................................... 71

signal.sys_tgkill ................................................................................................................. 71

signal.sys_tgkill.return ........................................................................................................ 72

signal.send_sig_queue ...................................................................................................... 72

signal.send_sig_queue.return ............................................................................................. 72

signal.pending ................................................................................................................... 73

signal.pending.return ......................................................................................................... 73

signal.handle ..................................................................................................................... 74

signal.handle.return ........................................................................................................... 74

SystemTap Tapset Reference

vi

signal.do_action ................................................................................................................ 74

signal.do_action.return ....................................................................................................... 75

signal.procmask ................................................................................................................ 75

signal.flush ........................................................................................................................ 76

vii

Preface

1. Document Conventions

This manual uses several conventions to highlight certain words and phrases and draw attention to
specific pieces of information.

In PDF and paper editions, this manual uses typefaces drawn from the Liberation Fonts1 set. The
Liberation Fonts set is also used in HTML editions if the set is installed on your system. If not,
alternative but equivalent typefaces are displayed. Note: Red Hat Enterprise Linux 5 and later includes
the Liberation Fonts set by default.

1.1. Typographic Conventions

Four typographic conventions are used to call attention to specific words and phrases. These
conventions, and the circumstances they apply to, are as follows.

Mono-spaced Bold

Used to highlight system input, including shell commands, file names and paths. Also used to highlight
key caps and key-combinations. For example:

To see the contents of the file my_next_bestselling_novel in your current
working directory, enter the cat my_next_bestselling_novel command at the
shell prompt and press Enter to execute the command.

The above includes a file name, a shell command and a key cap, all presented in Mono-spaced Bold
and all distinguishable thanks to context.

Key-combinations can be distinguished from key caps by the hyphen connecting each part of a key­combination. For example:

Press Enter to execute the command.

Press Ctrl+Alt+F1 to switch to the first virtual terminal. Press Ctrl+Alt+F7 to
return to your X-Windows session.

The first sentence highlights the particular key cap to press. The second highlights two sets of three
key caps, each set pressed simultaneously.

If source code is discussed, class names, methods, functions, variable names and returned values
mentioned within a paragraph will be presented as above, in Mono-spaced Bold. For example:

File-related classes include filesystem for file systems, file for files, and dir for
directories. Each class has its own associated set of permissions.

Proportional Bold

This denotes words or phrases encountered on a system, including application names; dialogue
box text; labelled buttons; check-box and radio button labels; menu titles and sub-menu titles. For
example:

1

https://fedorahosted.org/liberation-fonts/

Preface

viii

Choose System > Preferences > Mouse from the main menu bar to launch Mouse

Preferences. In the Buttons tab, click the Left-handed mouse check box and click
Close to switch the primary mouse button from the left to the right (making the mouse

suitable for use in the left hand).

To insert a special character into a gedit file, choose Applications > Accessories

> Character Map from the main menu bar. Next, choose Search > Find… from the
Character Map menu bar, type the name of the character in the Search field and

click Next. The character you sought will be highlighted in the Character Table.
Double-click this highlighted character to place it in the Text to copy field and then
click the Copy button. Now switch back to your document and choose Edit > Paste
from the gedit menu bar.

The above text includes application names; system-wide menu names and items; application-specific
menu names; and buttons and text found within a GUI interface, all presented in Proportional Bold and
all distinguishable by context.

Note the > shorthand used to indicate traversal through a menu and its sub-menus. This is to avoid
the difficult-to-follow 'Select Mouse from the Preferences sub-menu in the System menu of the main
menu bar' approach.

Mono-spaced Bold Italic or Proportional Bold Italic

Whether Mono-spaced Bold or Proportional Bold, the addition of Italics indicates replaceable or
variable text. Italics denotes text you do not input literally or displayed text that changes depending on
circumstance. For example:

To connect to a remote machine using ssh, type ssh [e-mail] at
a shell prompt. If the remote machine is example.com and your username on that
machine is john, type ssh [e-mail].

The mount -o remount file-system command remounts the named file
system. For example, to remount the /home file system, the command is mount -o
remount /home.

To see the version of a currently installed package, use the rpm -q package
command. It will return a result as follows: package-version-release.

Note the words in bold italics above — username, domain.name, file-system, package, version and
release. Each word is a placeholder, either for text you enter when issuing a command or for text
displayed by the system.

Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and
important term. For example:

When the Apache HTTP Server accepts requests, it dispatches child processes
or threads to handle them. This group of child processes or threads is known as
a server-pool. Under Apache HTTP Server 2.0, the responsibility for creating and
maintaining these server-pools has been abstracted to a group of modules called
Multi-Processing Modules (MPMs). Unlike other modules, only one module from the
MPM group can be loaded by the Apache HTTP Server.

1.2. Pull-quote Conventions

Two, commonly multi-line, data types are set off visually from the surrounding text.

Notes and Warnings

ix

Output sent to a terminal is set in Mono-spaced Roman and presented thus:

books Desktop documentation drafts mss photos stuff svn
books_tests Desktop1 downloads images notes scripts svgs

Source-code listings are also set in Mono-spaced Roman but are presented and highlighted as
follows:

package org.jboss.book.jca.ex1;

import javax.naming.InitialContext;

public class ExClient

{
public static void main(String args[])
throws Exception
{
InitialContext iniCtx = new InitialContext();
Object ref = iniCtx.lookup("EchoBean");
EchoHome home = (EchoHome) ref;
Echo echo = home.create();

System.out.println("Created Echo");

System.out.println("Echo.echo('Hello') = " + echo.echo("Hello"));
}

}

1.3. Notes and Warnings

Finally, we use three visual styles to draw attention to information that might otherwise be overlooked.

Note

A note is a tip or shortcut or alternative approach to the task at hand. Ignoring a note
should have no negative consequences, but you might miss out on a trick that makes your
life easier.

Important

Important boxes detail things that are easily missed: configuration changes that only
apply to the current session, or services that need restarting before an update will apply.
Ignoring Important boxes won't cause data loss but may cause irritation and frustration.

Preface

x

Warning

A Warning should not be ignored. Ignoring warnings will most likely cause data loss.

2. We Need Feedback!

If you find a typographical error in this manual, or if you have thought of a way to make this manual
better, we would love to hear from you! Please submit a report in Bugzilla: http://bugzilla.redhat.com/

bugzilla/ against the product Red_Hat_Enterprise_Linux.

When submitting a bug report, be sure to mention the manual's identifier: Tapset_Reference_Guide

If you have a suggestion for improving the documentation, try to be as specific as possible when
describing it. If you have found an error, please include the section number and some of the
surrounding text so we can find it easily.

Chapter 1.

1

Introduction

SystemTap provides free software (GPL) infrastructure to simplify the gathering of information about
the running Linux system. This assists diagnosis of a performance or functional problem. SystemTap
eliminates the need for the developer to go through the tedious and disruptive instrument, recompile,
install, and reboot sequence that may be otherwise required to collect data.

SystemTap provides a simple command line interface and scripting language for writing
instrumentation for a live, running kernel. This instrumentation uses probe points and functions
provided in the tapset library.

Simply put, tapsets are scripts that encapsulate knowledge about a kernel subsystem into pre-written
probes and functions that can be used by other scripts. Tapsets are analogous to libraries for C
programs. They hide the underlying details of a kernel area while exposing the key information needed
to manage and monitor that aspect of the kernel. They are typically developed by kernel subject­matter experts.

A tapset exposes the high-level data and state transitions of a subsystem. For the most part, good
tapset developers assume that SystemTap users know little to nothing about the kernel subsystem's
low-level details. As such, tapset developers write tapsets that help ordinary SystemTap users write
meaningful and useful SystemTap scripts.

1.1. Documentation Goals

This guide aims to document SystemTap's most useful and common tapset entries; it also contains
guidelines on proper tapset development and documentation. The tapset definitions contained in this
guide are extracted automatically from properly-formatted comments in the code of each tapset file. As
such, any revisions to the definitions in this guide should be applied directly to their respective tapset
file.

2

Chapter 2.

3

Tapset Development Guidelines

This chapter describes the upstream guidelines on proper tapset documentation. It also contains
information on how to properly document your tapsets, to ensure that they are properly defined in this
guide.

2.1. Writing Good Tapsets

The first step to writing good tapsets is to create a simple model of your subject area. For example, a
model of the process subsystem might include the following:

Key Data

• process ID

• parent process ID

• process group ID

State Transitions

• forked

• exec'd

• running

• stopped

• terminated

Note

Both lists are examples, and are not meant to represent a complete list.

Use your subsystem expertise to find probe points (function entries and exits) that expose the
elements of the model, then define probe aliases for those points. Be aware that some state
transitions can occur in more than one place. In those cases, an alias can place a probe in multiple
locations.

For example, process execs can occur in either the do_execve() or the compat_do_execve()
functions. The following alias inserts probes at the beginning of those functions:

probe kprocess.exec = kernel.function("do_execve"),
kernel.function("compat_do_execve")
{probe body}

Try to place probes on stable interfaces (i.e., functions that are unlikely to change at the interface
level) whenever possible. This will make the tapset less likely to break due to kernel changes. Where

Chapter 2. Tapset Development Guidelines

4

kernel version or architecture dependencies are unavoidable, use preprocessor conditionals (see the
stap(1) man page for details).

Fill in the probe bodies with the key data available at the probe points. Function entry probes
can access the entry parameters specified to the function, while exit probes can access the entry
parameters and the return value. Convert the data into meaningful forms where appropriate (e.g.,
bytes to kilobytes, state values to strings, etc).

You may need to use auxiliary functions to access or convert some of the data. Auxiliary functions
often use embedded C to do things that cannot be done in the SystemTap language, like access
structure fields in some contexts, follow linked lists, etc. You can use auxiliary functions defined in
other tapsets or write your own.

In the following example, copy_process() returns a pointer to the task_struct for the new
process. Note that the process ID of the new process is retrieved by calling task_pid() and passing
it the task_struct pointer. In this case, the auxiliary function is an embedded C function defined in
task.stp.

probe kprocess.create = kernel.function("copy_process").return
{
task = $return
new_pid = task_pid(task)
}

It is not advisable to write probes for every function. Most SystemTap users will not need or
understand them. Keep your tapsets simple and high-level.

2.2. Elements of a Tapset

The following sections describe the most important aspects of writing a tapset. Most of the content
herein is suitable for developers who wish to contribute to SystemTap's upstream library of tapsets.

2.2.1. Tapset Files

Tapset files are stored in src/tapset/ of the SystemTap GIT directory. Most tapset files are kept
at that level. If you have code that only works with a specific architecture or kernel version, you may
choose to put your tapset in the appropriate subdirectory.

Installed tapsets are located in /usr/share/systemtap/tapset/ or /usr/local/share/
systemtap/tapset.

Personal tapsets can be stored anywhere. However, to ensure that SystemTap can use them, use -I
tapset_directory to specify their location when invoking stap.

2.2.2. Namespace

Probe alias names should take the form tapset_name.probe_name. For example, the probe for
sending a signal could be named signal.send.

Global symbol names (probes, functions, and variables) should be unique accross all tapsets. This
helps avoid namespace collisions in scripts that use multiple tapsets. To ensure this, use tapset­specific prefixes in your global symbols.

Comments and Documentation

5

Internal symbol names should be prefixed with an underscore (_).

2.2.3. Comments and Documentation

All probes and functions should include comment blocks that describe their purpose, the data they
provide, and the context in which they run (e.g. interrupt, process, etc). Use comments in areas where
your intent may not be clear from reading the code.

Note that specially-formatted comments are automatically extracted from most tapsets and included
in this guide. This helps ensure that tapset contributors can write their tapset and document it in the
same place. The specified format for documenting tapsets is as follows:

/**
* probe tapset.name - Short summary of what the tapset does.
* @argument: Explanation of argument.
* @argument2: Explanation of argument2. Probes can have multiple
arguments.
*
* Context:
* A brief explanation of the tapset context.
* Note that the context should only be 1 paragraph short.
*
* Text that will appear under "Description."
*
* A new paragraph that will also appear under the heading "Description".
*
* Header:
* A paragraph that will appear under the heading "Header".
**/

For example:

/**
* probe vm.write_shared_copy- Page copy for shared page write.
* @address: The address of the shared write.
* @zero: Boolean indicating whether it is a zero page
* (can do a clear instead of a copy).
*
* Context:
* The process attempting the write.
*
* Fires when a write to a shared page requires a page copy. This is
* always preceded by a vm.shared_write.
**/

To override the automatically-generated Synopsis content, use:

* Synopsis:

Chapter 2. Tapset Development Guidelines

6

* New Synopsis string
*

For example:

/**
* probe signal.handle - Fires when the signal handler is invoked
* @sig: The signal number that invoked the signal handler
*
* Synopsis:
* <programlisting>static int handle_signal(unsigned long sig, siginfo_t
*info, struct k_sigaction *ka,
* sigset_t *oldset, struct pt_regs * regs)</programlisting>
*/

It is recommended that you use the <programlisting> tag in this instance, since overriding the
Synopsis content of an entry does not automatically form the necessary tags.

For the purposes of improving the DocBook XML output of your comments, you can also use the
following XML tags in your comments:

• command

• emphasis

• programlisting

• remark (tagged strings will appear in Publican beta builds of the document)

Chapter 3.

7

Context Functions

The context functions provide additional information about where an event occurred. These functions
can provide information such as a backtrace to where the event occured and the current register
values for the processor.

Name

print_regs — Print a register dump.

Synopsis

function print_regs()

Arguments

None

Name

execname — Returns the execname of a target process (or group of processes).

Synopsis

function execname:string()

Arguments

None

Name

pid — Returns the ID of a target process.

Synopsis

function pid:long()

Arguments

None

Name

tid — Returns the thread ID of a target process.

Chapter 3. Context Functions

8

Synopsis

function tid:long()

Arguments

None

Name

ppid — Returns the process ID of a target process's parent process.

Synopsis

function ppid:long()

Arguments

None

Name

pgrp — Returns the process group ID of the current process.

Synopsis

function pgrp:long()

Arguments

None

Name

sid — Returns the session ID of the current process.

Synopsis

function sid:long()

Arguments

None

9

Description

The session ID of a process is the process group ID of the session leader. Session ID is stored in the
signal_struct since Kernel 2.6.0.

Name

pexecname — Returns the execname of a target process's parent process.

Synopsis

function pexecname:string()

Arguments

None

Name

gid — Returns the group ID of a target process.

Synopsis

function gid:long()

Arguments

None

Name

egid — Returns the effective gid of a target process.

Synopsis

function egid:long()

Arguments

None

Name

uid — Returns the user ID of a target process.

Chapter 3. Context Functions

10

Synopsis

function uid:long()

Arguments

None

Name

euid — Return the effective uid of a target process.

Synopsis

function euid:long()

Arguments

None

Name

cpu — Returns the current cpu number.

Synopsis

function cpu:long()

Arguments

None

Name

pp — Return the probe point associated with the currently running probe handler,

Synopsis

function pp:string()

Arguments

None

11

Description

including alias and wildcard expansion effects

Context

The current probe point.

Name

registers_valid — Determines validity of register and u_register in current context.

Synopsis

function registers_valid:long()

Arguments

None

Description

Return 1 if register and u_register can be used in the current context, or 0 otherwise. For
example, registers_valid returns 0 when called from a begin or end probe.

Name

user_mode — Determines if probe point occurs in user-mode.

Synopsis

function user_mode:long()

Arguments

None

Description

Return 1 if the probe point occurred in user-mode.

Name

is_return — Determines if probe point is a return probe.

Chapter 3. Context Functions

12

Synopsis

function is_return:long()

Arguments

None

Description

Return 1 if the probe point is a return probe. Deprecated.

Name

target — Return the process ID of the target process.

Synopsis

function target:long()

Arguments

None

Name

stack_size — Return the size of the kernel stack.

Synopsis

function stack_size:long()

Arguments

None

Name

stack_used — Returns the amount of kernel stack used.

Synopsis

13

function stack_used:long()

Arguments

None

Description

Determines how many bytes are currently used in the kernel stack.

Name

stack_unused — Returns the amount of kernel stack currently available.

Synopsis

function stack_unused:long()

Arguments

None

Description

Determines how many bytes are currently available in the kernel stack.

Name

uaddr — User space address of current running task. EXPERIMENTAL.

Synopsis

function uaddr:long()

Arguments

None

Description

Returns the address in userspace that the current task was at when the probe occured. When the
current running task isn't a user space thread, or the address cannot be found, zero is returned. Can
be used to see where the current task is combined with usymname or symdata. Often the task will be
in the VDSO where it entered the kernel. FIXME - need VDSO tracking support #10080.

Chapter 3. Context Functions

14

Name

print_stack — Print out stack from string.

Synopsis

function print_stack(stk:string)

Arguments

stk

String with list of hexidecimal addresses.

Description

Perform a symbolic lookup of the addresses in the given string, which is assumed to be the result of a
prior call to backtrace.

Print one line per address, including the address, the name of the function containing the address, and
an estimate of its position within that function. Return nothing.

Name

probefunc — Return the probe point's function name, if known.

Synopsis

function probefunc:string()

Arguments

None

Name

probemod — Return the probe point's module name, if known.

Synopsis

function probemod:string()

Arguments

None

15

Name

modname — Return the kernel module name loaded at the address.

Synopsis

function modname:string(addr:long)

Arguments

addr

The address.

Description

Returns the module name associated with the given address if known. If not known it will return the
string “<unknown>”. If the address was not in a kernel module, but in the kernel itself, then the string
“kernel” will be returned.

Name

symname — Return the symbol associated with the given address.

Synopsis

function symname:string(addr:long)

Arguments

addr

The address to translate.

Description

Returns the (function) symbol name associated with the given address if known. If not known it will
return the hex string representation of addr.

Name

symdata — Return the symbol and module offset for the address.

Synopsis

Chapter 3. Context Functions

16

function symdata:string(addr:long)

Arguments

addr

The address to translate.

Description

Returns the (function) symbol name associated with the given address if known, plus the module
name (between brackets) and the offset inside the module, plus the size of the symbol function. If any
element is not known it will be ommitted and if the symbol name is unknown it will return the hex string
for the given address.

Name

usymname — Return the symbol of an address in the current task. EXPERIMENTAL!

Synopsis

function usymname:string(addr:long)

Arguments

addr

The address to translate.

Description

Returns the (function) symbol name associated with the given address if known. If not known it will
return the hex string representation of addr.

Name

usymdata — Return the symbol and module offset of an address. EXPERIMENTAL!

Synopsis

function usymdata:string(addr:long)

Arguments

addr

The address to translate.

17

Description

Returns the (function) symbol name associated with the given address in the current task if known,
plus the module name (between brackets) and the offset inside the module (shared library), plus the
size of the symbol function. If any element is not known it will be ommitted and if the symbol name is
unknown it will return the hex string for the given address.

Name

print_ustack — Print out stack for the current task from string. EXPERIMENTAL!

Synopsis

function print_ustack(stk:string)

Arguments

stk

String with list of hexidecimal addresses for the current task.

Description

Perform a symbolic lookup of the addresses in the given string, which is assumed to be the result of a
prior call to ubacktrace for the current task.

Print one line per address, including the address, the name of the function containing the address, and
an estimate of its position within that function. Return nothing.

Name

print_backtrace — Print stack back trace

Synopsis

function print_backtrace()

Arguments

None

Description

Equivalent to print_stack(backtrace), except that deeper stack nesting may be supported.
Return nothing.

Name

backtrace — Hex backtrace of current stack

Chapter 3. Context Functions

18

Synopsis

function backtrace:string()

Arguments

None

Description

Return a string of hex addresses that are a backtrace of the stack. Output may be truncated as per
maximum string length.

Name

caller — Return name and address of calling function

Synopsis

function caller:string()

Arguments

None

Description

Return the address and name of the calling function.

This is equivalent to calling

sprintf(“s 0xx”, symname(caller_addr, caller_addr)) Works only for return probes at this time.

Name

caller_addr — Return caller address

Synopsis

function caller_addr:long()

Arguments

None

19

Description

Return the address of the calling function. Works only for return probes at this time.

Name

print_ubacktrace — Print stack back trace for current task. EXPERIMENTAL!

Synopsis

function print_ubacktrace()

Arguments

None

Description

Equivalent to print_ustack(ubacktrace), except that deeper stack nesting may be supported.
Return nothing.

Name

ubacktrace — Hex backtrace of current task stack. EXPERIMENTAL!

Synopsis

function ubacktrace:string()

Arguments

None

Description

Return a string of hex addresses that are a backtrace of the stack of the current task. Output may
be truncated as per maximum string length. Returns empty string when current probe point cannot
determine user backtrace.

20

Chapter 4.

21

Timestamp Functions

Each timestamp function returns a value to indicate when a function is executed. These returned
values can then be used to indicate when an event occurred, provide an ordering for events, or
compute the amount of time elapsed between two time stamps.

Name

get_cycles — Processor cycle count.

Synopsis

function get_cycles:long()

Arguments

None

Description

Return the processor cycle counter value, or 0 if unavailable.

22

Chapter 5.

23

Memory Tapset

This family of probe points is used to probe memory-related events. It contains the following probe
points:

Name

vm_fault_contains — Test return value for page fault reason

Synopsis

function vm_fault_contains:long(value:long,test:long)

Arguments

value

The fault_type returned by vm.page_fault.return

test

The type of fault to test for (VM_FAULT_OOM or similar)

Name

vm.pagefault — Records that a page fault occurred.

Synopsis

vm.pagefault

Values

write_access

Indicates whether this was a write or read access; 1 indicates a write, while 0 indicates a read.

address

The address of the faulting memory access; i.e. the address that caused the page fault.

Context

The process which triggered the fault

Name

vm.pagefault.return — Indicates what type of fault occurred.

Chapter 5. Memory Tapset

24

Synopsis

vm.pagefault.return

Values

fault_type

Returns either 0 (VM_FAULT_OOM) for out of memory faults, 2 (VM_FAULT_MINOR) for minor
faults, 3 (VM_FAULT_MAJOR) for major faults, or 1 (VM_FAULT_SIGBUS) if the fault was neither
OOM, minor fault, nor major fault.

Name

addr_to_node — Returns which node a given address belongs to within a NUMA system.

Synopsis

function addr_to_node:long(addr:long)

Arguments

addr

The address of the faulting memory access.

Name

vm.write_shared — Attempts at writing to a shared page.

Synopsis

vm.write_shared

Values

address

The address of the shared write.

Context

The context is the process attempting the write.

Description

Fires when a process attempts to write to a shared page. If a copy is necessary, this will be followed
by a vm.write_shared_copy.

25

Name

vm.write_shared_copy — Page copy for shared page write.

Synopsis

vm.write_shared_copy

Values

zero

Boolean indicating whether it is a zero page (can do a clear instead of a copy).

address

The address of the shared write.

Context

The process attempting the write.

Description

Fires when a write to a shared page requires a page copy. This is always preceded by a
vm.shared_write.

Name

vm.mmap — Fires when an mmap is requested.

Synopsis

vm.mmap

Values

length

The length of the memory segment

address

The requested address

Context

The process calling mmap.

Name

vm.munmap — Fires when an munmap is requested.

Chapter 5. Memory Tapset

26

Synopsis

vm.munmap

Values

length

The length of the memory segment

address

The requested address

Context

The process calling munmap.

Name

vm.brk — Fires when a brk is requested (i.e. the heap will be resized).

Synopsis

vm.brk

Values

length

The length of the memory segment

address

The requested address

Context

The process calling brk.

Name

vm.oom_kill — Fires when a thread is selected for termination by the OOM killer.

Synopsis

vm.oom_kill

27

Values

task

The task being killed

Context

The process that tried to consume excessive memory, and thus triggered the OOM.

28

Chapter 6.

29

IO Scheduler Tapset

This family of probe points is used to probe IO scheduler activities. It contains the following probe
points:

Name

ioscheduler.elv_next_request — Fires when a request is retrieved from the request queue

Synopsis

ioscheduler.elv_next_request

Values

elevator_name

The type of I/O elevator currently enabled

Name

ioscheduler.elv_next_request.return — Fires when a request retrieval issues a return signal

Synopsis

ioscheduler.elv_next_request.return

Values

req_flags

Request flags

req

Address of the request

disk_major

Disk major number of the request

disk_minor

Disk minor number of the request

Name

ioscheduler.elv_add_request — A request was added to the request queue

Chapter 6. IO Scheduler Tapset

30

Synopsis

ioscheduler.elv_add_request

Values

req_flags

Request flags

req

Address of the request

disk_major

Disk major number of the request

elevator_name

The type of I/O elevator currently enabled

disk_minor

Disk minor number of the request

Name

ioscheduler.elv_completed_request — Fires when a request is completed

Synopsis

ioscheduler.elv_completed_request

Values

req_flags

Request flags

req

Address of the request

disk_major

Disk major number of the request

elevator_name

The type of I/O elevator currently enabled

disk_minor

Disk minor number of the request

Chapter 7.

31

SCSI Tapset

This family of probe points is used to probe SCSI activities. It contains the following probe points:

Name

scsi.ioentry — Prepares a SCSI mid-layer request

Synopsis

scsi.ioentry

Values

disk_major

The major number of the disk (-1 if no information)

device_state

The current state of the device.

disk_minor

The minor number of the disk (-1 if no information)

Name

scsi.iodispatching — SCSI mid-layer dispatched low-level SCSI command

Synopsis

scsi.iodispatching

Values

lun

The lun number

req_bufflen

The request buffer length

host_no

The host number

device_state

The current state of the device.

dev_id

The scsi device id

Chapter 7. SCSI Tapset

32

channel

The channel number

data_direction

The data_direction specifies whether this command is from/to the device. 0
(DMA_BIDIRECTIONAL), 1 (DMA_TO_DEVICE), 2 (DMA_FROM_DEVICE), 3 (DMA_NONE)

request_buffer

The request buffer address

Name

scsi.iodone — SCSI command completed by low level driver and enqueued into the done queue.

Synopsis

scsi.iodone

Values

lun

The lun number

host_no

The host number

device_state

The current state of the device

dev_id

The scsi device id

channel

The channel number

data_direction

The data_direction specifies whether this command is from/to the device.

Name

scsi.iocompleted — SCSI mid-layer running the completion processing for block device I/O requests

Synopsis

scsi.iocompleted

33

Values

lun

The lun number

host_no

The host number

device_state

The current state of the device

dev_id

The scsi device id

channel

The channel number

data_direction

The data_direction specifies whether this command is from/to the device

goodbytes

The bytes completed.

34

Chapter 8.

35

Networking Tapset

This family of probe points is used to probe the activities of the network device and protocol layers.

Name

netdev.receive — Data recieved from network device.

Synopsis

netdev.receive

Values

protocol

Protocol of recieved packet.

dev_name

The name of the device. e.g: eth0, ath1.

length

The length of the receiving buffer.

Name

netdev.transmit — Network device transmitting buffer

Synopsis

netdev.transmit

Values

protocol

The protocol of this packet.

dev_name

The name of the device. e.g: eth0, ath1.

length

The length of the transmit buffer.

truesize

The size of the the data to be transmitted.

Chapter 8. Networking Tapset

36

Name

tcp.sendmsg — Sending a tcp message

Synopsis

tcp.sendmsg

Values

name

Name of this probe

size

Number of bytes to send

sock

Network socket

Context

The process which sends a tcp message

Name

tcp.sendmsg.return — Sending TCP message is done

Synopsis

tcp.sendmsg.return

Values

name

Name of this probe

size

Number of bytes sent or error code if an error occurred.

Context

The process which sends a tcp message

Name

tcp.recvmsg — Receiving TCP message

37

Synopsis

tcp.recvmsg

Values

saddr

A string representing the source IP address

daddr

A string representing the destination IP address

name

Name of this probe

sport

TCP source port

dport

TCP destination port

size

Number of bytes to be received

sock

Network socket

Context

The process which receives a tcp message

Name

tcp.recvmsg.return — Receiving TCP message complete

Synopsis

tcp.recvmsg.return

Values

saddr

A string representing the source IP address

daddr

A string representing the destination IP address

name

Name of this probe

Chapter 8. Networking Tapset

38

sport

TCP source port

dport

TCP destination port

size

Number of bytes received or error code if an error occurred.

Context

The process which receives a tcp message

Name

tcp.disconnect — TCP socket disconnection

Synopsis

tcp.disconnect

Values

saddr

A string representing the source IP address

daddr

A string representing the destination IP address

flags

TCP flags (e.g. FIN, etc)

name

Name of this probe

sport

TCP source port

dport

TCP destination port

sock

Network socket

Context

The process which disconnects tcp

Name

tcp.disconnect.return — TCP socket disconnection complete

39

Synopsis

tcp.disconnect.return

Values

ret

Error code (0: no error)

name

Name of this probe

Context

The process which disconnects tcp

Name

tcp.setsockopt — Call to setsockopt

Synopsis

tcp.setsockopt

Values

optstr

Resolves optname to a human-readable format

level

The level at which the socket options will be manipulated

optlen

Used to access values for setsockopt

name

Name of this probe

optname

TCP socket options (e.g. TCP_NODELAY, TCP_MAXSEG, etc)

sock

Network socket

Context

The process which calls setsockopt

Chapter 8. Networking Tapset

40

Name

tcp.setsockopt.return — Return from setsockopt

Synopsis

tcp.setsockopt.return

Values

ret

Error code (0: no error)

name

Name of this probe

Context

The process which calls setsockopt

Name

tcp.receive — Called when a TCP packet is received

Synopsis

tcp.receive

Values

urg

TCP URG flag

psh

TCP PSH flag

rst

TCP RST flag

dport

TCP destination port

saddr

A string representing the source IP address

daddr

A string representing the destination IP address

41

ack

TCP ACK flag

syn

TCP SYN flag

fin

TCP FIN flag

sport

TCP source port

Name

udp.sendmsg — Fires whenever a process sends a UDP message

Synopsis

udp.sendmsg

Values

name

The name of this probe

size

Number of bytes sent by the process

sock

Network socket used by the process

Context

The process which sent a UDP message

Name

udp.sendmsg.return — Fires whenever an attempt to send a UDP message is completed

Synopsis

udp.sendmsg.return

Values

name

The name of this probe

Chapter 8. Networking Tapset

42

size

Number of bytes sent by the process

Context

The process which sent a UDP message

Name

udp.recvmsg — Fires whenever a UDP message is received

Synopsis

udp.recvmsg

Values

name

The name of this probe

size

Number of bytes received by the process

sock

Network socket used by the process

Context

The process which received a UDP message

Name

udp.recvmsg.return — Fires whenever an attempt to receive a UDP message received is completed

Synopsis

udp.recvmsg.return

Values

name

The name of this probe

size

Number of bytes received by the process

43

Context

The process which received a UDP message

Name

udp.disconnect — Fires when a process requests for a UDP disconnection

Synopsis

udp.disconnect

Values

flags

Flags (e.g. FIN, etc)

name

The name of this probe

sock

Network socket used by the process

Context

The process which requests a UDP disconnection

Name

udp.disconnect.return — UDP has been disconnected successfully

Synopsis

udp.disconnect.return

Values

ret

Error code (0: no error)

name

The name of this probe

Context

The process which requested a UDP disconnection

Chapter 8. Networking Tapset

44

Name

ip_ntop — returns a string representation from an integer IP number

Synopsis

function ip_ntop:string(addr:long)

Arguments

addr

the ip represented as an integer

Chapter 9.

45

Socket Tapset

This family of probe points is used to probe socket activities. It contains the following probe points:

Name

socket.send — Message sent on a socket.

Synopsis

socket.send

Values

success

Was send successful? (1 = yes, 0 = no)

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Size of message sent (in bytes) or error code if success = 0

type

Socket type value

family

Protocol family value

Context

The message sender

Name

socket.receive — Message received on a socket.

Synopsis

Chapter 9. Socket Tapset

46

socket.receive

Values

success

Was send successful? (1 = yes, 0 = no)

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Size of message received (in bytes) or error code if success = 0

type

Socket type value

family

Protocol family value

Context

The message receiver

Name

socket.sendmsg — Message is currently being sent on a socket.

Synopsis

socket.sendmsg

Values

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

47

state

Socket state value

size

Message size in bytes

type

Socket type value

family

Protocol family value

Context

The message sender

Description

Fires at the beginning of sending a message on a socket via the the sock_sendmsg function

Name

socket.sendmsg.return — Return from socket.sendmsg.

Synopsis

socket.sendmsg.return

Values

success

Was send successful? (1 = yes, 0 = no)

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Size of message sent (in bytes) or error code if success = 0

type

Socket type value

Chapter 9. Socket Tapset

48

family

Protocol family value

Context

The message sender.

Description

Fires at the conclusion of sending a message on a socket via the sock_sendmsg function

Name

socket.recvmsg — Message being received on socket

Synopsis

socket.recvmsg

Values

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Message size in bytes

type

Socket type value

family

Protocol family value

Context

The message receiver.

Description

Fires at the beginning of receiving a message on a socket via the sock_recvmsg function

49

Name

socket.recvmsg.return — Return from Message being received on socket

Synopsis

socket.recvmsg.return

Values

success

Was receive successful? (1 = yes, 0 = no)

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Size of message received (in bytes) or error code if success = 0

type

Socket type value

family

Protocol family value

Context

The message receiver.

Description

Fires at the conclusion of receiving a message on a socket via the sock_recvmsg function.

Name

socket.aio_write — Message send via sock_aio_write

Synopsis

Chapter 9. Socket Tapset

50

socket.aio_write

Values

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Message size in bytes

type

Socket type value

family

Protocol family value

Context

The message sender

Description

Fires at the beginning of sending a message on a socket via the sock_aio_write function

Name

socket.aio_write.return — Conclusion of message send via sock_aio_write

Synopsis

socket.aio_write.return

Values

success

Was receive successful? (1 = yes, 0 = no)

protocol

Protocol value

51

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Size of message received (in bytes) or error code if success = 0

type

Socket type value

family

Protocol family value

Context

The message receiver.

Description

Fires at the conclusion of sending a message on a socket via the sock_aio_write function

Name

socket.aio_read — Receiving message via sock_aio_read

Synopsis

socket.aio_read

Values

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Message size in bytes

Chapter 9. Socket Tapset

52

type

Socket type value

family

Protocol family value

Context

The message sender

Description

Fires at the beginning of receiving a message on a socket via the sock_aio_read function

Name

socket.aio_read.return — Conclusion of message received via sock_aio_read

Synopsis

socket.aio_read.return

Values

success

Was receive successful? (1 = yes, 0 = no)

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Size of message received (in bytes) or error code if success = 0

type

Socket type value

family

Protocol family value

Context

The message receiver.

53

Description

Fires at the conclusion of receiving a message on a socket via the sock_aio_read function

Name

socket.writev — Message sent via socket_writev

Synopsis

socket.writev

Values

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Message size in bytes

type

Socket type value

family

Protocol family value

Context

The message sender

Description

Fires at the beginning of sending a message on a socket via the sock_writev function

Name

socket.writev.return — Conclusion of message sent via socket_writev

Synopsis

Chapter 9. Socket Tapset

54

socket.writev.return

Values

success

Was send successful? (1 = yes, 0 = no)

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Size of message sent (in bytes) or error code if success = 0

type

Socket type value

family

Protocol family value

Context

The message receiver.

Description

Fires at the conclusion of sending a message on a socket via the sock_writev function

Name

socket.readv — Receiving a message via sock_readv

Synopsis

socket.readv

Values

protocol

Protocol value

55

flags

Socket flags value

name

Name of this probe

state

Socket state value

size

Message size in bytes

type

Socket type value

family

Protocol family value

Context

The message sender

Description

Fires at the beginning of receiving a message on a socket via the sock_readv function

Name

socket.readv.return — Conclusion of receiving a message via sock_readv

Synopsis

socket.readv.return

Values

success

Was receive successful? (1 = yes, 0 = no)

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

Chapter 9. Socket Tapset

56

size

Size of message received (in bytes) or error code if success = 0

type

Socket type value

family

Protocol family value

Context

The message receiver.

Description

Fires at the conclusion of receiving a message on a socket via the sock_readv function

Name

socket.create — Creation of a socket

Synopsis

socket.create

Values

protocol

Protocol value

name

Name of this probe

requester

Requested by user process or the kernel (1 = kernel, 0 = user)

type

Socket type value

family

Protocol family value

Context

The requester (see requester variable)

Description

Fires at the beginning of creating a socket.

57

Name

socket.create.return — Return from Creation of a socket

Synopsis

socket.create.return

Values

success

Was socket creation successful? (1 = yes, 0 = no)

protocol

Protocol value

err

Error code if success == 0

name

Name of this probe

requester

Requested by user process or the kernel (1 = kernel, 0 = user)

type

Socket type value

family

Protocol family value

Context

The requester (user process or kernel)

Description

Fires at the conclusion of creating a socket.

Name

socket.close — Close a socket

Synopsis

socket.close

Chapter 9. Socket Tapset

58

Values

protocol

Protocol value

flags

Socket flags value

name

Name of this probe

state

Socket state value

type

Socket type value

family

Protocol family value

Context

The requester (user process or kernel)

Description

Fires at the beginning of closing a socket.

Name

socket.close.return — Return from closing a socket

Synopsis

socket.close.return

Values

name

Name of this probe

Context

The requester (user process or kernel)

Description

Fires at the conclusion of closing a socket.

59

Name

sock_prot_num2str — Given a protocol number, return a string representation.

Synopsis

function sock_prot_num2str:string(proto:long)

Arguments

proto

The protocol number.

Name

sock_prot_str2num — Given a protocol name (string), return the corresponding protocol number.

Synopsis

function sock_prot_str2num:long(proto:string)

Arguments

proto

The protocol name.

Name

sock_fam_num2str — Given a protocol family number, return a string representation.

Synopsis

function sock_fam_num2str:string(family:long)

Arguments

family

The family number.

Name

sock_fam_str2num — Given a protocol family name (string), return the corresponding

Chapter 9. Socket Tapset

60

Synopsis

function sock_fam_str2num:long(family:string)

Arguments

family

The family name.

Description

protocol family number.

Name

sock_state_num2str — Given a socket state number, return a string representation.

Synopsis

function sock_state_num2str:string(state:long)

Arguments

state

The state number.

Name

sock_state_str2num — Given a socket state string, return the corresponding state number.

Synopsis

function sock_state_str2num:long(state:string)

Arguments

state

The state name.

Chapter 10.

61

Kernel Process Tapset

This family of probe points is used to probe process-related activities. It contains the following probe
points:

Name

kprocess.create — Fires whenever a new process is successfully created

Synopsis

kprocess.create

Values

new_pid

The PID of the newly created process

Context

Parent of the created process.

Description

Fires whenever a new process is successfully created, either as a result of fork (or one of its syscall
variants), or a new kernel thread.

Name

kprocess.start — Starting new process

Synopsis

kprocess.start

Values

None

Context

Newly created process.

Description

Fires immediately before a new process begins execution.

Chapter 10. Kernel Process Tapset

62

Name

kprocess.exec — Attempt to exec to a new program

Synopsis

kprocess.exec

Values

filename

The path to the new executable

Context

The caller of exec.

Description

Fires whenever a process attempts to exec to a new program.

Name

kprocess.exec_complete — Return from exec to a new program

Synopsis

kprocess.exec_complete

Values

success

A boolean indicating whether the exec was successful

errno

The error number resulting from the exec

Context

On success, the context of the new executable. On failure, remains in the context of the caller.

Description

Fires at the completion of an exec call.

Name

kprocess.exit — Exit from process

63

Synopsis

kprocess.exit

Values

code

The exit code of the process

Context

The process which is terminating.

Description

Fires when a process terminates. This will always be followed by a kprocess.release, though the latter
may be delayed if the process waits in a zombie state.

Name

kprocess.release — Process released

Synopsis

kprocess.release

Values

pid

PID of the process being released

task

A task handle to the process being released

Context

The context of the parent, if it wanted notification of this process' termination, else the context of the
process itself.

Description

Fires when a process is released from the kernel. This always follows a kprocess.exit, though it may
be delayed somewhat if the process waits in a zombie state.

64

Chapter 11.

65

Signal Tapset

This family of probe points is used to probe signal activities. It contains the following probe points:

Name

signal.send — Signal being sent to a process

Synopsis

signal.send

Values

send2queue

Indicates whether the signal is sent to an existing sigqueue

name

The name of the function used to send out the signal

task

A task handle to the signal recipient

sinfo

The address of siginfo struct

si_code

Indicates the signal type

sig_name

A string representation of the signal

sig

The number of the signal

shared

Indicates whether the signal is shared by the thread group

sig_pid

The PID of the process receiving the signal

pid_name

The name of the signal recipient

Context

The signal's sender.

Chapter 11. Signal Tapset

66

Name

signal.send.return — Signal being sent to a process completed

Synopsis

signal.send.return

Values

retstr

The return value to either __group_send_sig_info, specific_send_sig_info, or
send_sigqueue

send2queue

Indicates whether the sent signal was sent to an existing sigqueue

name

The name of the function used to send out the signal

shared

Indicates whether the sent signal is shared by the thread group.

Context

The signal's sender.

Description

Possible __group_send_sig_info and specific_send_sig_info return values are as follows;

0 -- The signal is sucessfully sent to a process, which means that <1> the signal was ignored by the

receiving process, <2> this is a non-RT signal and the system already has one queued, and <3> the
signal was successfully added to the sigqueue of the receiving process.

-EAGAIN -- The sigqueue of the receiving process is overflowing, the signal was RT, and the signal
was sent by a user using something other than kill.

Possible send_group_sigqueue and send_sigqueue return values are as follows;

0 -- The signal was either sucessfully added into the sigqueue of the receiving process, or a
SI_TIMER entry is already queued (in which case, the overrun count will be simply incremented).

1 -- The signal was ignored by the receiving process.

-1 -- (send_sigqueue only) The task was marked exiting, allowing * posix_timer_event to

redirect it to the group leader.

Name

signal.checkperm — Check being performed on a sent signal

67

Synopsis

signal.checkperm

Values

name

Name of the probe point; default value is signal.checkperm

task

A task handle to the signal recipient

sinfo

The address of the siginfo structure

si_code

Indicates the signal type

sig_name

A string representation of the signal

sig

The number of the signal

pid_name

Name of the process receiving the signal

sig_pid

The PID of the process receiving the signal

Name

signal.checkperm.return — Check performed on a sent signal completed

Synopsis

signal.checkperm.return

Values

retstr

Return value as a string

name

Name of the probe point; default value is signal.checkperm

Name

signal.wakeup — Sleeping process being wakened for signal

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Synopsis

signal.wakeup

Values

resume

Indicates whether to wake up a task in a STOPPED or TRACED state

state_mask

A string representation indicating the mask of task states to wake. Possible values are
TASK_INTERRUPTIBLE, TASK_STOPPED, TASK_TRACED, and TASK_INTERRUPTIBLE.

pid_name

Name of the process to wake

sig_pid

The PID of the process to wake

Name

signal.check_ignored — Checking to see signal is ignored

Synopsis

signal.check_ignored

Values

sig_name

A string representation of the signal

sig

The number of the signal

pid_name

Name of the process receiving the signal

sig_pid

The PID of the process receiving the signal

Name

signal.check_ignored.return — Check to see signal is ignored completed

69

Synopsis

signal.check_ignored.return

Values

retstr

Return value as a string

name

Name of the probe point; default value is signal.checkperm

Name

signal.force_segv — Forcing send of SIGSEGV

Synopsis

signal.force_segv

Values

sig_name

A string representation of the signal

sig

The number of the signal

pid_name

Name of the process receiving the signal

sig_pid

The PID of the process receiving the signal

Name

signal.force_segv.return — Forcing send of SIGSEGV complete

Synopsis

signal.force_segv.return

Values

retstr

Return value as a string

Chapter 11. Signal Tapset

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name

Name of the probe point; default value is force_sigsegv

Name

signal.syskill — Sending kill signal to a process

Synopsis

signal.syskill

Values

sig

The specific signal sent to the process

pid

The PID of the process receiving the signal

Name

signal.syskill.return — Sending kill signal completed

Synopsis

signal.syskill.return

Values

None

Name

signal.sys_tkill — Sending a kill signal to a thread

Synopsis

signal.sys_tkill

Values

sig_name

The specific signal sent to the process

71

sig

The specific signal sent to the process

pid

The PID of the process receiving the kill signal

Description

The tkill call is analogous to kill(2), except that it also allows a process within a specific thread
group to be targetted. Such processes are targetted through their unique thread IDs (TID).

Name

signal.systkill.return — Sending kill signal to a thread completed

Synopsis

signal.systkill.return

Values

None

Name

signal.sys_tgkill — Sending kill signal to a thread group

Synopsis

signal.sys_tgkill

Values

sig_name

A string representation of the signal

sig

The specific kill signal sent to the process

pid

The PID of the thread receiving the kill signal

tgid

The thread group ID of the thread receiving the kill signal

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Description

The tgkill call is similar to tkill, except that it also allows the caller to specify the thread group ID
of the thread to be signalled. This protects against TID reuse.

Name

signal.sys_tgkill.return — Sending kill signal to a thread group completed

Synopsis

signal.sys_tgkill.return

Values

None

Name

signal.send_sig_queue — Queuing a signal to a process

Synopsis

signal.send_sig_queue

Values

sigqueue_addr

The address of the signal queue

sig_name

A string representation of the signal

sig

The queued signal

pid_name

Name of the process to which the signal is queued

sig_pid

The PID of the process to which the signal is queued

Name

signal.send_sig_queue.return — Queuing a signal to a process completed

73

Synopsis

signal.send_sig_queue.return

Values

retstr

Return value as a string

Name

signal.pending — Examining pending signal

Synopsis

signal.pending

Values

sigset_size

The size of the user-space signal set

sigset_add

The address of the user-space signal set (sigset_t)

Description

This probe is used to examine a set of signals pending for delivery to a specific thread. This normally
occurs when the do_sigpending kernel function is executed.

Name

signal.pending.return — Examination of pending signal completed

Synopsis

signal.pending.return

Values

retstr

Return value as a string

Chapter 11. Signal Tapset

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Name

signal.handle — Signal handler being invoked

Synopsis

signal.handle

Values

regs

The address of the kernel-mode stack area

sig_code

The si_code value of the siginfo signal

sig_mode

Indicates whether the signal was a user-mode or kernel-mode signal

sinfo

The address of the siginfo table

oldset_addr

The address of the bitmask array of blocked signals

sig

The signal number that invoked the signal handler

ka_addr

The address of the k_sigaction table associated with the signal

Name

signal.handle.return — Signal handler invocation completed

Synopsis

signal.handle.return

Values

retstr

Return value as a string

Name

signal.do_action — Examining or changing a signal action

75

Synopsis

signal.do_action

Values

sa_mask

The new mask of the signal

oldsigact_addr

The address of the old sigaction struct associated with the signal

sig

The signal to be examined/changed

sa_handler

The new handler of the signal

sigact_addr

The address of the new sigaction struct associated with the signal

Name

signal.do_action.return — Examining or changing a signal action completed

Synopsis

signal.do_action.return

Values

retstr

Return value as a string

Name

signal.procmask — Examining or changing blocked signals

Synopsis

signal.procmask

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76

Values

how

Indicates how to change the blocked signals; possible values are SIG_BLOCK=0 (for blocking
signals), SIG_UNBLOCK=1 (for unblocking signals), and SIG_SETMASK=2 for setting the signal
mask.

oldsigset_addr

The old address of the signal set (sigset_t)

sigset

The actual value to be set for sigset_t

sigset_addr

The address of the signal set (sigset_t) to be implemented

Name

signal.flush — Flusing all pending signals for a task

Synopsis

signal.flush

Values

task

The task handler of the process performing the flush

pid_name

The name of the process associated with the task performing the flush

sig_pid

The PID of the process associated with the task performing the flush