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Documentation: coresight: convert txt to rst 

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in doc-guide [1]

[1] https://www.kernel.org/doc/html/latest/doc-guide/sphinx.html

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Signed-off-by: default avatarPhong Tran <tranmanphong@gmail.com>
Reviewed-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 34d5f4f2
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Documentation/trace/coresight-cpu-debug.txt → Documentation/trace/coresight-cpu-debug.rst
View file @ fe13225f
Coresight CPU Debug Module
==========================
==========================
Coresight CPU Debug Module
==========================
Author: Leo Yan <leo.yan@linaro.org>
Date: April 5th, 2017
:Author: Leo Yan <leo.yan@linaro.org>
:Date: April 5th, 2017
Introduction
------------
......@@ -69,6 +70,7 @@ Before accessing debug registers, we should ensure the clock and power domain
have been enabled properly. In ARMv8-a ARM (ARM DDI 0487A.k) chapter 'H9.1
Debug registers', the debug registers are spread into two domains: the debug
domain and the CPU domain.
::
+---------------+
| |
......@@ -125,18 +127,21 @@ If you want to enable debugging functionality at boot time, you can add
"coresight_cpu_debug.enable=1" to the kernel command line parameter.
The driver also can work as module, so can enable the debugging when insmod
module:
# insmod coresight_cpu_debug.ko debug=1
module::
# insmod coresight_cpu_debug.ko debug=1
When boot time or insmod module you have not enabled the debugging, the driver
uses the debugfs file system to provide a knob to dynamically enable or disable
debugging:
To enable it, write a '1' into /sys/kernel/debug/coresight_cpu_debug/enable:
# echo 1 > /sys/kernel/debug/coresight_cpu_debug/enable
To enable it, write a '1' into /sys/kernel/debug/coresight_cpu_debug/enable::
# echo 1 > /sys/kernel/debug/coresight_cpu_debug/enable
To disable it, write a '0' into /sys/kernel/debug/coresight_cpu_debug/enable::
To disable it, write a '0' into /sys/kernel/debug/coresight_cpu_debug/enable:
# echo 0 > /sys/kernel/debug/coresight_cpu_debug/enable
# echo 0 > /sys/kernel/debug/coresight_cpu_debug/enable
As explained in chapter "Clock and power domain", if you are working on one
platform which has idle states to power off debug logic and the power
......@@ -154,34 +159,34 @@ subsystem, more specifically by using the "/dev/cpu_dma_latency"
interface (see Documentation/power/pm_qos_interface.rst for more
details). As specified in the PM QoS documentation the requested
parameter will stay in effect until the file descriptor is released.
For example:
For example::
# exec 3<> /dev/cpu_dma_latency; echo 0 >&3
...
Do some work...
...
# exec 3<>-
# exec 3<> /dev/cpu_dma_latency; echo 0 >&3
...
Do some work...
...
# exec 3<>-
The same can also be done from an application program.
Disable specific CPU's specific idle state from cpuidle sysfs (see
Documentation/admin-guide/pm/cpuidle.rst):
# echo 1 > /sys/devices/system/cpu/cpu$cpu/cpuidle/state$state/disable
Documentation/admin-guide/pm/cpuidle.rst)::
# echo 1 > /sys/devices/system/cpu/cpu$cpu/cpuidle/state$state/disable
Output format
-------------
Here is an example of the debugging output format:
ARM external debug module:
coresight-cpu-debug 850000.debug: CPU[0]:
coresight-cpu-debug 850000.debug: EDPRSR: 00000001 (Power:On DLK:Unlock)
coresight-cpu-debug 850000.debug: EDPCSR: handle_IPI+0x174/0x1d8
coresight-cpu-debug 850000.debug: EDCIDSR: 00000000
coresight-cpu-debug 850000.debug: EDVIDSR: 90000000 (State:Non-secure Mode:EL1/0 Width:64bits VMID:0)
coresight-cpu-debug 852000.debug: CPU[1]:
coresight-cpu-debug 852000.debug: EDPRSR: 00000001 (Power:On DLK:Unlock)
coresight-cpu-debug 852000.debug: EDPCSR: debug_notifier_call+0x23c/0x358
coresight-cpu-debug 852000.debug: EDCIDSR: 00000000
coresight-cpu-debug 852000.debug: EDVIDSR: 90000000 (State:Non-secure Mode:EL1/0 Width:64bits VMID:0)
Here is an example of the debugging output format::
ARM external debug module:
coresight-cpu-debug 850000.debug: CPU[0]:
coresight-cpu-debug 850000.debug: EDPRSR: 00000001 (Power:On DLK:Unlock)
coresight-cpu-debug 850000.debug: EDPCSR: handle_IPI+0x174/0x1d8
coresight-cpu-debug 850000.debug: EDCIDSR: 00000000
coresight-cpu-debug 850000.debug: EDVIDSR: 90000000 (State:Non-secure Mode:EL1/0 Width:64bits VMID:0)
coresight-cpu-debug 852000.debug: CPU[1]:
coresight-cpu-debug 852000.debug: EDPRSR: 00000001 (Power:On DLK:Unlock)
coresight-cpu-debug 852000.debug: EDPCSR: debug_notifier_call+0x23c/0x358
coresight-cpu-debug 852000.debug: EDCIDSR: 00000000
coresight-cpu-debug 852000.debug: EDVIDSR: 90000000 (State:Non-secure Mode:EL1/0 Width:64bits VMID:0)
Documentation/trace/coresight.txt → Documentation/trace/coresight.rst
View file @ fe13225f
Coresight - HW Assisted Tracing on ARM
======================================
======================================
Coresight - HW Assisted Tracing on ARM
======================================
Author: Mathieu Poirier <mathieu.poirier@linaro.org>
Date: September 11th, 2014
:Author: Mathieu Poirier <mathieu.poirier@linaro.org>
:Date: September 11th, 2014
Introduction
------------
......@@ -26,7 +27,7 @@ implementation, either storing the compressed stream in a memory buffer or
creating an interface to the outside world where data can be transferred to a
host without fear of filling up the onboard coresight memory buffer.
At typical coresight system would look like this:
At typical coresight system would look like this::
*****************************************************************
**************************** AMBA AXI ****************************===||
......@@ -95,15 +96,24 @@ Acronyms and Classification
Acronyms:
PTM: Program Trace Macrocell
ETM: Embedded Trace Macrocell
STM: System trace Macrocell
ETB: Embedded Trace Buffer
ITM: Instrumentation Trace Macrocell
TPIU: Trace Port Interface Unit
TMC-ETR: Trace Memory Controller, configured as Embedded Trace Router
TMC-ETF: Trace Memory Controller, configured as Embedded Trace FIFO
CTI: Cross Trigger Interface
PTM:
Program Trace Macrocell
ETM:
Embedded Trace Macrocell
STM:
System trace Macrocell
ETB:
Embedded Trace Buffer
ITM:
Instrumentation Trace Macrocell
TPIU:
Trace Port Interface Unit
TMC-ETR:
Trace Memory Controller, configured as Embedded Trace Router
TMC-ETF:
Trace Memory Controller, configured as Embedded Trace FIFO
CTI:
Cross Trigger Interface
Classification:
......@@ -118,7 +128,7 @@ Misc:
Device Tree Bindings
----------------------
--------------------
See Documentation/devicetree/bindings/arm/coresight.txt for details.
......@@ -133,70 +143,70 @@ The coresight framework provides a central point to represent, configure and
manage coresight devices on a platform. Any coresight compliant device can
register with the framework for as long as they use the right APIs:
struct coresight_device *coresight_register(struct coresight_desc *desc);
void coresight_unregister(struct coresight_device *csdev);
.. c:function:: struct coresight_device *coresight_register(struct coresight_desc *desc);
.. c:function:: void coresight_unregister(struct coresight_device *csdev);
The registering function is taking a "struct coresight_device *csdev" and
The registering function is taking a ``struct coresight_desc *desc`` and
register the device with the core framework. The unregister function takes
a reference to a "struct coresight_device", obtained at registration time.
a reference to a ``struct coresight_device *csdev`` obtained at registration time.
If everything goes well during the registration process the new devices will
show up under /sys/bus/coresight/devices, as showns here for a TC2 platform:
show up under /sys/bus/coresight/devices, as showns here for a TC2 platform::
root:~# ls /sys/bus/coresight/devices/
replicator 20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm
20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm
root:~#
root:~# ls /sys/bus/coresight/devices/
replicator 20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm
20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm
root:~#
The functions take a "struct coresight_device", which looks like this:
The functions take a ``struct coresight_device``, which looks like this::
struct coresight_desc {
struct coresight_desc {
enum coresight_dev_type type;
struct coresight_dev_subtype subtype;
const struct coresight_ops *ops;
struct coresight_platform_data *pdata;
struct device *dev;
const struct attribute_group **groups;
};
};
The "coresight_dev_type" identifies what the device is, i.e, source link or
sink while the "coresight_dev_subtype" will characterise that type further.
The "struct coresight_ops" is mandatory and will tell the framework how to
The ``struct coresight_ops`` is mandatory and will tell the framework how to
perform base operations related to the components, each component having
a different set of requirement. For that "struct coresight_ops_sink",
"struct coresight_ops_link" and "struct coresight_ops_source" have been
a different set of requirement. For that ``struct coresight_ops_sink``,
``struct coresight_ops_link`` and ``struct coresight_ops_source`` have been
provided.
The next field, "struct coresight_platform_data *pdata" is acquired by calling
"of_get_coresight_platform_data()", as part of the driver's _probe routine and
"struct device *dev" gets the device reference embedded in the "amba_device":
The next field ``struct coresight_platform_data *pdata`` is acquired by calling
``of_get_coresight_platform_data()``, as part of the driver's _probe routine and
``struct device *dev`` gets the device reference embedded in the ``amba_device``::
static int etm_probe(struct amba_device *adev, const struct amba_id *id)
{
static int etm_probe(struct amba_device *adev, const struct amba_id *id)
{
...
...
drvdata->dev = &adev->dev;
...
}
}
Specific class of device (source, link, or sink) have generic operations
that can be performed on them (see "struct coresight_ops"). The
"**groups" is a list of sysfs entries pertaining to operations
that can be performed on them (see ``struct coresight_ops``). The ``**groups``
is a list of sysfs entries pertaining to operations
specific to that component only. "Implementation defined" customisations are
expected to be accessed and controlled using those entries.
Device Naming scheme
------------------------
--------------------
The devices that appear on the "coresight" bus were named the same as their
parent devices, i.e, the real devices that appears on AMBA bus or the platform bus.
Thus the names were based on the Linux Open Firmware layer naming convention,
which follows the base physical address of the device followed by the device
type. e.g:
type. e.g::
root:~# ls /sys/bus/coresight/devices/
root:~# ls /sys/bus/coresight/devices/
20010000.etf 20040000.funnel 20100000.stm 22040000.etm
22140000.etm 230c0000.funnel 23240000.etm 20030000.tpiu
20070000.etr 20120000.replicator 220c0000.funnel
......@@ -205,7 +215,7 @@ root:~# ls /sys/bus/coresight/devices/
However, with the introduction of ACPI support, the names of the real
devices are a bit cryptic and non-obvious. Thus, a new naming scheme was
introduced to use more generic names based on the type of the device. The
following rules apply:
following rules apply::
1) Devices that are bound to CPUs, are named based on the CPU logical
number.
......@@ -220,9 +230,9 @@ following rules apply:
e.g, tmc_etf0, tmc_etr0, funnel0, funnel1
Thus, with the new scheme the devices could appear as :
Thus, with the new scheme the devices could appear as ::
root:~# ls /sys/bus/coresight/devices/
root:~# ls /sys/bus/coresight/devices/
etm0 etm1 etm2 etm3 etm4 etm5 funnel0
funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0
......@@ -234,9 +244,12 @@ the system under specified locations.
How to use the tracer modules
-----------------------------
There are two ways to use the Coresight framework: 1) using the perf cmd line
tools and 2) interacting directly with the Coresight devices using the sysFS
interface. Preference is given to the former as using the sysFS interface
There are two ways to use the Coresight framework:
1. using the perf cmd line tools.
2. interacting directly with the Coresight devices using the sysFS interface.
Preference is given to the former as using the sysFS interface
requires a deep understanding of the Coresight HW. The following sections
provide details on using both methods.
......@@ -245,107 +258,107 @@ provide details on using both methods.
Before trace collection can start, a coresight sink needs to be identified.
There is no limit on the amount of sinks (nor sources) that can be enabled at
any given moment. As a generic operation, all device pertaining to the sink
class will have an "active" entry in sysfs:
root:/sys/bus/coresight/devices# ls
replicator 20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm
20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm
root:/sys/bus/coresight/devices# ls 20010000.etb
enable_sink status trigger_cntr
root:/sys/bus/coresight/devices# echo 1 > 20010000.etb/enable_sink
root:/sys/bus/coresight/devices# cat 20010000.etb/enable_sink
1
root:/sys/bus/coresight/devices#
class will have an "active" entry in sysfs::
root:/sys/bus/coresight/devices# ls
replicator 20030000.tpiu 2201c000.ptm 2203c000.etm 2203e000.etm
20010000.etb 20040000.funnel 2201d000.ptm 2203d000.etm
root:/sys/bus/coresight/devices# ls 20010000.etb
enable_sink status trigger_cntr
root:/sys/bus/coresight/devices# echo 1 > 20010000.etb/enable_sink
root:/sys/bus/coresight/devices# cat 20010000.etb/enable_sink
1
root:/sys/bus/coresight/devices#
At boot time the current etm3x driver will configure the first address
comparator with "_stext" and "_etext", essentially tracing any instruction
that falls within that range. As such "enabling" a source will immediately
trigger a trace capture:
root:/sys/bus/coresight/devices# echo 1 > 2201c000.ptm/enable_source
root:/sys/bus/coresight/devices# cat 2201c000.ptm/enable_source
1
root:/sys/bus/coresight/devices# cat 20010000.etb/status
Depth: 0x2000
Status: 0x1
RAM read ptr: 0x0
RAM wrt ptr: 0x19d3 <----- The write pointer is moving
Trigger cnt: 0x0
Control: 0x1
Flush status: 0x0
Flush ctrl: 0x2001
root:/sys/bus/coresight/devices#
Trace collection is stopped the same way:
root:/sys/bus/coresight/devices# echo 0 > 2201c000.ptm/enable_source
root:/sys/bus/coresight/devices#
The content of the ETB buffer can be harvested directly from /dev:
root:/sys/bus/coresight/devices# dd if=/dev/20010000.etb \
of=~/cstrace.bin
64+0 records in
64+0 records out
32768 bytes (33 kB) copied, 0.00125258 s, 26.2 MB/s
root:/sys/bus/coresight/devices#
trigger a trace capture::
root:/sys/bus/coresight/devices# echo 1 > 2201c000.ptm/enable_source
root:/sys/bus/coresight/devices# cat 2201c000.ptm/enable_source
1
root:/sys/bus/coresight/devices# cat 20010000.etb/status
Depth: 0x2000
Status: 0x1
RAM read ptr: 0x0
RAM wrt ptr: 0x19d3 <----- The write pointer is moving
Trigger cnt: 0x0
Control: 0x1
Flush status: 0x0
Flush ctrl: 0x2001
root:/sys/bus/coresight/devices#
Trace collection is stopped the same way::
root:/sys/bus/coresight/devices# echo 0 > 2201c000.ptm/enable_source
root:/sys/bus/coresight/devices#
The content of the ETB buffer can be harvested directly from /dev::
root:/sys/bus/coresight/devices# dd if=/dev/20010000.etb \
of=~/cstrace.bin
64+0 records in
64+0 records out
32768 bytes (33 kB) copied, 0.00125258 s, 26.2 MB/s
root:/sys/bus/coresight/devices#
The file cstrace.bin can be decompressed using "ptm2human", DS-5 or Trace32.
Following is a DS-5 output of an experimental loop that increments a variable up
to a certain value. The example is simple and yet provides a glimpse of the
wealth of possibilities that coresight provides.
Info Tracing enabled
Instruction 106378866 0x8026B53C E52DE004 false PUSH {lr}
Instruction 0 0x8026B540 E24DD00C false SUB sp,sp,#0xc
Instruction 0 0x8026B544 E3A03000 false MOV r3,#0
Instruction 0 0x8026B548 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Timestamp Timestamp: 17106715833
Instruction 319 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 9 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 7 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 7 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 10 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 6 0x8026B560 EE1D3F30 false MRC p15,#0x0,r3,c13,c0,#1
Instruction 0 0x8026B564 E1A0100D false MOV r1,sp
Instruction 0 0x8026B568 E3C12D7F false BIC r2,r1,#0x1fc0
Instruction 0 0x8026B56C E3C2203F false BIC r2,r2,#0x3f
Instruction 0 0x8026B570 E59D1004 false LDR r1,[sp,#4]
Instruction 0 0x8026B574 E59F0010 false LDR r0,[pc,#16] ; [0x8026B58C] = 0x80550368
Instruction 0 0x8026B578 E592200C false LDR r2,[r2,#0xc]
Instruction 0 0x8026B57C E59221D0 false LDR r2,[r2,#0x1d0]
Instruction 0 0x8026B580 EB07A4CF true BL {pc}+0x1e9344 ; 0x804548c4
Info Tracing enabled
Instruction 13570831 0x8026B584 E28DD00C false ADD sp,sp,#0xc
Instruction 0 0x8026B588 E8BD8000 true LDM sp!,{pc}
Timestamp Timestamp: 17107041535
::
Info Tracing enabled
Instruction 106378866 0x8026B53C E52DE004 false PUSH {lr}
Instruction 0 0x8026B540 E24DD00C false SUB sp,sp,#0xc
Instruction 0 0x8026B544 E3A03000 false MOV r3,#0
Instruction 0 0x8026B548 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Timestamp Timestamp: 17106715833
Instruction 319 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 9 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 7 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 7 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 10 0x8026B54C E59D3004 false LDR r3,[sp,#4]
Instruction 0 0x8026B550 E3530004 false CMP r3,#4
Instruction 0 0x8026B554 E2833001 false ADD r3,r3,#1
Instruction 0 0x8026B558 E58D3004 false STR r3,[sp,#4]
Instruction 0 0x8026B55C DAFFFFFA true BLE {pc}-0x10 ; 0x8026b54c
Instruction 6 0x8026B560 EE1D3F30 false MRC p15,#0x0,r3,c13,c0,#1
Instruction 0 0x8026B564 E1A0100D false MOV r1,sp
Instruction 0 0x8026B568 E3C12D7F false BIC r2,r1,#0x1fc0
Instruction 0 0x8026B56C E3C2203F false BIC r2,r2,#0x3f
Instruction 0 0x8026B570 E59D1004 false LDR r1,[sp,#4]
Instruction 0 0x8026B574 E59F0010 false LDR r0,[pc,#16] ; [0x8026B58C] = 0x80550368
Instruction 0 0x8026B578 E592200C false LDR r2,[r2,#0xc]
Instruction 0 0x8026B57C E59221D0 false LDR r2,[r2,#0x1d0]
Instruction 0 0x8026B580 EB07A4CF true BL {pc}+0x1e9344 ; 0x804548c4
Info Tracing enabled
Instruction 13570831 0x8026B584 E28DD00C false ADD sp,sp,#0xc
Instruction 0 0x8026B588 E8BD8000 true LDM sp!,{pc}
Timestamp Timestamp: 17107041535
2) Using perf framework:
......@@ -370,19 +383,18 @@ A Coresight PMU works the same way as any other PMU, i.e the name of the PMU is
listed along with configuration options within forward slashes '/'. Since a
Coresight system will typically have more than one sink, the name of the sink to
work with needs to be specified as an event option.
On newer kernels the available sinks are listed in sysFS under:
($SYSFS)/bus/event_source/devices/cs_etm/sinks/
On newer kernels the available sinks are listed in sysFS under
($SYSFS)/bus/event_source/devices/cs_etm/sinks/::
root@localhost:/sys/bus/event_source/devices/cs_etm/sinks# ls
tmc_etf0 tmc_etr0 tpiu0
On older kernels, this may need to be found from the list of coresight devices,
available under ($SYSFS)/bus/coresight/devices/:
available under ($SYSFS)/bus/coresight/devices/::
root:~# ls /sys/bus/coresight/devices/
etm0 etm1 etm2 etm3 etm4 etm5 funnel0
funnel1 funnel2 replicator0 stm0 tmc_etf0 tmc_etr0 tpiu0
root@linaro-nano:~# perf record -e cs_etm/@tmc_etr0/u --per-thread program
As mentioned above in section "Device Naming scheme", the names of the devices could
......@@ -395,14 +407,14 @@ to use for the trace session.
More information on the above and other example on how to use Coresight with
the perf tools can be found in the "HOWTO.md" file of the openCSD gitHub
repository [3].
repository [#third]_.
2.1) AutoFDO analysis using the perf tools:
perf can be used to record and analyze trace of programs.
Execution can be recorded using 'perf record' with the cs_etm event,
specifying the name of the sink to record to, e.g:
specifying the name of the sink to record to, e.g::
perf record -e cs_etm/@tmc_etr0/u --per-thread
......@@ -421,12 +433,14 @@ Generating coverage files for Feedback Directed Optimization: AutoFDO
'perf inject' accepts the --itrace option in which case tracing data is
removed and replaced with the synthesized events. e.g.
::
perf inject --itrace --strip -i perf.data -o perf.data.new
Below is an example of using ARM ETM for autoFDO. It requires autofdo
(https://github.com/google/autofdo) and gcc version 5. The bubble
sort example is from the AutoFDO tutorial (https://gcc.gnu.org/wiki/AutoFDO/Tutorial).
::
$ gcc-5 -O3 sort.c -o sort
$ taskset -c 2 ./sort
......@@ -455,28 +469,30 @@ difference is that clients are driving the trace capture rather
than the program flow through the code.
As with any other CoreSight component, specifics about the STM tracer can be
found in sysfs with more information on each entry being found in [1]:
found in sysfs with more information on each entry being found in [#first]_::
root@genericarmv8:~# ls /sys/bus/coresight/devices/stm0
enable_source hwevent_select port_enable subsystem uevent
hwevent_enable mgmt port_select traceid
root@genericarmv8:~#
root@genericarmv8:~# ls /sys/bus/coresight/devices/stm0
enable_source hwevent_select port_enable subsystem uevent
hwevent_enable mgmt port_select traceid
root@genericarmv8:~#
Like any other source a sink needs to be identified and the STM enabled before
being used:
being used::
root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/tmc_etf0/enable_sink
root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/stm0/enable_source
root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/tmc_etf0/enable_sink
root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/stm0/enable_source
From there user space applications can request and use channels using the devfs
interface provided for that purpose by the generic STM API:
interface provided for that purpose by the generic STM API::
root@genericarmv8:~# ls -l /dev/stm0
crw------- 1 root root 10, 61 Jan 3 18:11 /dev/stm0
root@genericarmv8:~#
Details on how to use the generic STM API can be found here [#second]_.
root@genericarmv8:~# ls -l /dev/stm0
crw------- 1 root root 10, 61 Jan 3 18:11 /dev/stm0
root@genericarmv8:~#
.. [#first] Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
Details on how to use the generic STM API can be found here [2].
.. [#second] Documentation/trace/stm.rst
[1]. Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
[2]. Documentation/trace/stm.rst
[3]. https://github.com/Linaro/perf-opencsd
.. [#third] https://github.com/Linaro/perf-opencsd
Documentation/trace/index.rst
View file @ fe13225f
......@@ -23,3 +23,5 @@ Linux Tracing Technologies
intel_th
stm
sys-t
coresight
coresight-cpu-debug
MAINTAINERS
View file @ fe13225f
......@@ -1582,8 +1582,8 @@ R: Suzuki K Poulose <suzuki.poulose@arm.com>
L: linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
S: Maintained
F: drivers/hwtracing/coresight/*
F: Documentation/trace/coresight.txt
F: Documentation/trace/coresight-cpu-debug.txt
F: Documentation/trace/coresight.rst
F: Documentation/trace/coresight-cpu-debug.rst
F: Documentation/devicetree/bindings/arm/coresight.txt
F: Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt
F: Documentation/ABI/testing/sysfs-bus-coresight-devices-*
......
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