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Igor Lubashev c22e150e3a perf tools: Add helpers to use capabilities if present
Add utilities to help checking capabilities of the running procss.  Make
perf link with libcap, if it is available. If no libcap-dev[el],
fallback to the geteuid() == 0 test used before.

Committer notes:

  $ perf test python
  18: 'import perf' in python                               : FAILED!
  $ perf test -v python
  Couldn't bump rlimit(MEMLOCK), failures may take place when creating BPF maps, etc
  18: 'import perf' in python                               :
  --- start ---
  test child forked, pid 23288
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
  ImportError: /tmp/build/perf/python/perf.so: undefined symbol: cap_get_flag
  test child finished with -1
  ---- end ----
  'import perf' in python: FAILED!
  $

This happens because differently from the perf binary generated with
this patch applied:

  $ ldd /tmp/build/perf/perf | grep libcap
  	libcap.so.2 => /lib64/libcap.so.2 (0x00007f724a4ef000)
  $

The python binding isn't linking with libcap:

  $ ldd /tmp/build/perf/python/perf.so | grep libcap
  $

So add 'cap' to the 'extra_libraries' variable in
tools/perf/util/setup.py, and rebuild:

  $ perf test python
  18: 'import perf' in python                               : Ok
  $

If we explicitely disable libcap it also continues to work:

  $ make NO_LIBCAP=1 -C tools/perf O=/tmp/build/perf install-bin
    $ ldd /tmp/build/perf/perf | grep libcap
  $ ldd /tmp/build/perf/python/perf.so | grep libcap
  $ perf test python
  18: 'import perf' in python                               : Ok
  $

Signed-off-by: Igor Lubashev <ilubashe@akamai.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
[ split from a larger patch ]
Link: http://lkml.kernel.org/r/8a1e76cf5c7c9796d0d4d240fbaa85305298aafa.1565188228.git.ilubashe@akamai.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-08-14 10:48:39 -03:00
Documentation RISC-V updates for v5.3-rc4 2019-08-10 16:31:47 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch RISC-V updates for v5.3-rc4 2019-08-10 16:31:47 -07:00
block block, bfq: handle NULL return value by bfq_init_rq() 2019-08-08 07:31:50 -06:00
certs Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
crypto USB / PHY patches for 5.3-rc1 2019-07-11 15:40:06 -07:00
drivers Bug fix for NTB MSI kernel compile warning 2019-08-11 10:13:53 -07:00
fs dax fixes v5.3-rc4 2019-08-11 13:15:10 -07:00
include Bugfixes (arm and x86) and cleanups. 2019-08-09 15:46:29 -07:00
init Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
ipc Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-10 15:48:02 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-06 17:11:59 -07:00
mm mm/memremap: Fix reuse of pgmap instances with internal references 2019-08-09 14:16:15 -07:00
net net: dsa: sja1105: Fix memory leak on meta state machine error path 2019-08-06 14:37:02 -07:00
samples treewide: remove SPDX "WITH Linux-syscall-note" from kernel-space headers again 2019-07-25 11:05:10 +02:00
scripts kbuild: show hint if subdir-y/m is used to visit module Makefile 2019-08-10 01:45:31 +09:00
security selinux/stable-5.3 PR 20190801 2019-08-02 18:40:49 -07:00
sound sound fixes for 5.3-rc4 2019-08-09 09:21:27 -07:00
tools perf tools: Add helpers to use capabilities if present 2019-08-14 10:48:39 -03:00
usr kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test 2019-07-23 10:45:46 +02:00
virt KVM/arm fixes for 5.3, take #2 2019-08-09 16:53:50 +02:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.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: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: Add compilation database file 2019-07-27 12:18:19 +09:00
.mailmap MAINTAINERS: Update my email address 2019-07-22 14:57:50 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Remove references to dead website. 2019-07-19 12:22:04 -07:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Char/misc fixes for 5.3-rc4 2019-08-10 12:24:20 -07:00
Makefile Linux 5.3-rc4 2019-08-11 13:26:41 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

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.