[PATCH v13 0/7] Introduce perf check subcommand

[Aditya Gupta <adityag@linux.ibm.com>]

The Problem
===========

Currently the presence of a feature is checked with a combination of
perf version --build-options and greps, such as:

    perf version --build-options | grep " on .* HAVE_FEATURE"

This relies on the output of perf version, and is a common pattern in tests.

Proposed solution
=================

As suggested by contributors in:
https://lore.kernel.org/linux-perf-users/ZMPWk5K63tadmDlU@kernel.org/

Introduce a subcommand "perf check feature", with which
scripts can test for presence of a feature or multiple features, such as:

    perf check feature HAVE_LIBTRACEEVENT  (feature macro)

    or

    perf check feature libtraceevent       (feature name)

    or

    perf check feature LibTraceEvent       (case-insensitive)

    or

    perf check feature libtraceevent,bpf   (multiple features)

The usage of "perf version --build-options | grep" has been replaced in two
tests, with "perf check feature" command

Also, to not duplicate the same feature list at multiple places, a new global
'supported_features' array has been introduced in builtin.h, so both commands
'perf check feature' and 'perf version --build-options' use the same array

'supported_features' feature is an array of 'struct feature_support', which
also has the name of the feature, macro used to test it's presence, and a
is_builtin member, which will be 0 if feature not built-in, and 1 if built-in

Architectures Tested
====================
* x86_64
* ppc64le

Commands ran for testing (Fedora & RHEL):

    sudo dnf install -y libtraceevent-devel
    make clean
    make -j$(nproc)
    ./perf check feature libtraceevent,bpf; echo Return Code: $?
    ./perf check feature libtraceevent; echo Return Code: $?
    
    sudo ./perf test -v "task-analyzer"
    sudo ./perf test -v "probe libc's inet_pton & backtrace it with ping"
    sudo ./perf test -v "Use vfs_getname probe to get syscall args filenames"
    
    sudo dnf remove -y libtraceevent-devel
    make clean
    make NO_LIBTRACEEVENT=1 -j$(nproc)
    ./perf check feature libtraceevent,bpf; echo Return Code: $?
    ./perf check feature libtraceevent; echo Return Code: $?
    
    sudo ./perf test -v "task-analyzer"
    sudo ./perf test -v "probe libc's inet_pton & backtrace it with ping"
    sudo ./perf test -v "Use vfs_getname probe to get syscall args filenames"

Git tree
========

Git tree with this patch series applied for testing:
https://github.com/adi-g15-ibm/linux/tree/perf-check-feature-v13

Changelog
=========

v13:
+ patch #1: add fix for parse_options_subcommand not setting usage string
+ patch #2: if unknown feature name passed, print "please use 'perf version
  --build-options' to see which ones are available"
+ patch #6: fix inconsistency in feature names (dwarf-unwind-support & get_cpuid)
+ patch #7: add more features to feature_list

v12
+ patch #1: fix comment to mention argv[0] instead of argv[1]
+ patch #2: fix alignment

v11
+ patch #1: fix build error due to const *const instead of const*

v10
+ patch #1: use 'strdup' instead of 'malloc+memcpy'
+ patch #1: replace '-q' with '--quiet' in doc
+ patch #1: add usage for perf check

V9
+ make 'feature' a subcommand instead of an option
+ make feature name/macro check case-insensitive
+ rename 'FEATURE_SUPPORT' as 'FEATURE_STATUS'
+ rebase on upstream perf-tools-next

V8
+ handle return value of 'malloc' in patch #1
+ fix error due to strncpy depending on source string's length

V7
+ modified patch #1 to fix compile issue, and add feature to allow
  multiple comma-separated features

V6
+ rebased to perf-tools-next/perf-tools-next
+ modified patch #1 to include FEATURE_SUPPORT("bpf_skeletons", HAVE_BPF_SKEL)

V5
+ invert return value of 'has_support', but return value of perf check --feature
according to shell convention

V4
+ invert return value of perf check --feature

V3
+ simplified has_support code in builtin-check.c (patch #1)
+ modified patch #3 and patch #4 according to change in return value in patch #1

V2
+ improved the patch series with suggestions from Namhyung
+ fix incorrect return value, added -q option, and moved array definition to
  perf-check.c

V1
+ changed subcommand name to 'perf check --feature'
+ added documentation for perf check
+ support both macro (eg. HAVE_LIBTRACEEVENT), and name (eg. libtraceevent) as
  input to 'perf check --feature'
+ change subject and descriptions of all patch mentioning perf check instead of
  perf build

V0: Previous patch series: https://lore.kernel.org/linux-perf-users/20230825061125.24312-1-adityag@linux.ibm.com/

Aditya Gupta (6):
  tools/lib/subcmd: Don't free the usage string
  perf check: Introduce 'check' subcommand
  perf version: Update --build-options to use 'supported_features' array
  tools/perf/tests: Update test_task_analyzer.sh to use perf check
    feature
  perf: Fix inconsistencies in feature names
  perf: Add more features to supported_features list

Athira Rajeev (1):
  tools/perf/tests: Update probe_vfs_getname.sh script to use perf check
    feature

 tools/lib/subcmd/parse-options.c              |   8 +-
 tools/perf/Build                              |   1 +
 tools/perf/Documentation/perf-check.txt       | 106 +++++++++
 tools/perf/builtin-check.c                    | 205 ++++++++++++++++++
 tools/perf/builtin-kmem.c                     |   2 +
 tools/perf/builtin-kvm.c                      |   3 +
 tools/perf/builtin-kwork.c                    |   3 +
 tools/perf/builtin-lock.c                     |   3 +
 tools/perf/builtin-mem.c                      |   3 +
 tools/perf/builtin-sched.c                    |   3 +
 tools/perf/builtin-version.c                  |  43 +---
 tools/perf/builtin.h                          |  17 ++
 tools/perf/perf.c                             |   1 +
 .../perf/tests/shell/lib/probe_vfs_getname.sh |   4 +-
 .../shell/record+probe_libc_inet_pton.sh      |   5 +-
 .../shell/record+script_probe_vfs_getname.sh  |   5 +-
 tools/perf/tests/shell/test_task_analyzer.sh  |   4 +-
 17 files changed, 370 insertions(+), 46 deletions(-)
 create mode 100644 tools/perf/Documentation/perf-check.txt
 create mode 100644 tools/perf/builtin-check.c

-- 
2.45.2