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Thomas Richter 5aa98879ef s390/cpum_sf: prohibit callchain data collection
CPU Measurement sampling facility on s390 does not support
perf tool collection of callchain data using --call-graph
option. The sampling facility collects samples in a ring
buffer which includes only the instruction address the
samples were taken. When the ring buffer hits a watermark,
a measurement alert interrupt is triggered and handled
by the performance measurement unit (PMU) device driver.
It collects the samples and feeds each sample to the
perf ring buffer in the common code via functions
perf_prepare_sample()/perf_output_sample(). When function
perf_prepare_sample() is called to collect sample data's
callchain, user register values or stack area, invalid
data is picked, because the context of the collected
information does not match the context when the sample
was taken.

There is currently no way to provide the callchain and other
information, because the hardware sampler does not collect this
information.

Therefore prohibit sampling when the user requests a callchain graph
from the hardware sampler. Return -EOPNOTSUPP to the user in this
case.
If call chains are really wanted, users need to specify software
event cpu-clock to get the callchain information from a
software event.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
2020-07-01 20:02:33 +02:00
arch s390/cpum_sf: prohibit callchain data collection 2020-07-01 20:02:33 +02:00
block block-5.8-2020-06-26 2020-06-27 08:59:32 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto crypto: drbg - always try to free Jitter RNG instance 2020-06-15 17:38:54 +10:00
Documentation Peter Zijlstra says: 2020-06-28 09:42:47 -07:00
drivers ARM: OMAP fixes for v5.8 2020-06-28 14:57:14 -07:00
fs - Fix build regression on v4.8 and older 2020-06-28 11:42:16 -07:00
include A single DocBook fix. 2020-06-28 11:59:08 -07:00
init Kbuild updates for v5.8 (2nd) 2020-06-13 13:29:16 -07:00
ipc mmap locking API: use coccinelle to convert mmap_sem rwsem call sites 2020-06-09 09:39:14 -07:00
kernel Peter Zijlstra says: 2020-06-28 10:37:39 -07:00
lib Peter Zijlstra says: 2020-06-28 09:42:47 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/memory_hotplug.c: fix false softlockup during pfn range removal 2020-06-26 00:27:38 -07:00
net NFS Client Bugfixes for Linux 5.8-rc 2020-06-27 09:35:47 -07:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-06-25 18:27:40 -07:00
scripts Paul E. McKenney says: 2020-06-28 10:29:38 -07:00
security selinux/stable-5.8 PR 20200621 2020-06-21 15:41:24 -07:00
sound sound fixes for 5.8-rc3 2020-06-25 09:15:24 -07:00
tools Peter Zijlstra says: 2020-06-28 10:16:15 -07:00
usr bpfilter: match bit size of bpfilter_umh to that of the kernel 2020-05-17 18:52:01 +09:00
virt MIPS: 2020-06-12 11:05:52 -07:00
.clang-format block: add bio_for_each_bvec_all() 2020-05-25 11:25:24 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: generate vmlinux.symvers and reuse it for the second modpost 2020-06-06 23:38:12 +09:00
.mailmap A fair amount of stuff this time around, dominated by yet another massive 2020-06-01 15:45:27 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS mailmap: change email for Ricardo Ribalda 2020-05-25 18:59:59 -06:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS ARM: SoC fixes for v5.8 2020-06-28 14:55:18 -07:00
Makefile Linux 5.8-rc3 2020-06-28 15:00:24 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.