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SystemTap Tapset Reference
Red Hat Enterprise Linux 5
For SystemTap in Red Hat Enterprise Linux 5
Edition 1
Red Hat Enterprise Linux Documentation
Abstract
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 the latest upstream version of SystemTap.
Preface
Chapter 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 subject-matter 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.
Chapter 2. 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 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 tapset-specific prefixes in your global symbols.
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: * 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:
commandemphasisprogramlistingremark(tagged strings will appear in Publican beta builds of the document)
Chapter 3. 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.
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
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.
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
Description
including alias and wildcard expansion effects
Context
The current probe point.
Name
registers_valid — Determines validity of registeru_register
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_validName
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.
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
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.
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
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
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.
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
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
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
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.
Chapter 4. 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.
Chapter 5. 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;
1indicates a write, while0indicates 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.
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, or1(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.
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.
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
Values
task- The task being killed
Context
The process that tried to consume excessive memory, and thus triggered the OOM.
Chapter 6. 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
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. 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
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
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.
Chapter 8. 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.
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
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
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
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
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
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
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
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
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. 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
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
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
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
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
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
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
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.
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
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
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
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.
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
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.
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
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. 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.
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
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.
Chapter 11. 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
siginfostruct 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.
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, orsend_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
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
siginfostructure 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
Synopsis
signal.wakeup
Values
resume- Indicates whether to wake up a task in a
STOPPEDorTRACEDstate state_mask- A string representation indicating the mask of task states to wake. Possible values are
TASK_INTERRUPTIBLE,TASK_STOPPED,TASK_TRACED, andTASK_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
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
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
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
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
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
Name
signal.handle — Signal handler being invoked
Synopsis
signal.handle
Values
regs- The address of the kernel-mode stack area
sig_code- The
si_codevalue of thesiginfosignal sig_mode- Indicates whether the signal was a user-mode or kernel-mode signal
sinfo- The address of the
siginfotable 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_sigactiontable 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
Synopsis
signal.do_action
Values
sa_mask- The new mask of the signal
oldsigact_addr- The address of the old
sigactionstruct 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
sigactionstruct 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
Values
how- Indicates how to change the blocked signals; possible values are
SIG_BLOCK=0(for blocking signals),SIG_UNBLOCK=1(for unblocking signals), andSIG_SETMASK=2for 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
Appendix A. Revision History
| Revision History | |||
|---|---|---|---|
| Revision 1.0-5.400 | 2013-10-31 | Rüdiger Landmann | |
| |||
| Revision 1.0-5 | 2012-07-18 | Anthony Towns | |
| |||
| Revision 1.0-0 | Wed Jun 17 2009 | Don Domingo | |
| |||
Legal Notice
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.
