perf build: Fix installation directory for bpf

Perf tool build and install is controlled via makefile. Make install creates directories and copies files. Among them are header files installed in /usr/lib/include/perf/bpf/.

However all listed examples are installing its header files in
/usr/lib/<tool-name>/...[/include]/header.h
and not in
/usr/lib/include/<tool-name>/.../header.h.

Background information:
Building the Fedora 28 glibc RPM on s390x and s390 fails on s390 (gcc -m31) as gcc is not able to find header-files like stdbool.h. In the glibc.spec file, you can see that glibc is configured with "--with-headers". In this case, first -nostdinc is added to the CFLAGS and then further include paths are added via -isystem. One of those paths should contain header files like stdbool.h.

In order to get this path, gcc is invoked with:
- on Fedora 28 (with 4.18 kernel):

  $ gcc -print-file-name=include
  /usr/lib/gcc/s390x-redhat-linux/8/include
  $ gcc -m31 -print-file-name=include
  /usr/lib/gcc/s390x-redhat-linux/8/../../../../lib/include
  => If perf is installed, this is: /usr/lib/include
  On my machine this directory is only containing the directory "perf".
  If perf is not installed gcc returns: /usr/lib/gcc/s390x-redhat-linux/8/\
						include

-on Ubuntu 18.04 (with 4.15 kernel):

  $ gcc  -print-file-name=include
  /usr/lib/gcc/s390x-linux-gnu/7/include
  $ gcc -m31 -print-file-name=include
  /usr/lib/gcc/s390x-linux-gnu/7/include
  => gcc returns the correct path even if perf is installed.

In each case, the introduction of the subdirectory /usr/lib/include leads to the regression that one can not build the glibc RPM for s390 anymore as gcc can not find headers like stdbool.h.

To remedy this install bpf.h to /usr/lib/perf/include/bpf/bpf.h

Output before using command ./perf test -Fv 40:

echo '...[bpf-program-source]...' | /usr/bin/clang ... \
		 -I/root/lib/include/perf/bpf ...
                             ^^^^^^^^^^^^
...
[root@p23lp27 perf]# ./perf test -F 40
40: BPF filter                                            :
40.1: Basic BPF filtering                                 : Ok
40.2: BPF pinning                                         : Ok
40.3: BPF prologue generation                             : Ok
40.4: BPF relocation checker                              : Ok

[root@p23lp27 perf]#

Output after using command ./perf test -Fv 40:

echo '...[bpf-program-source]...' | /usr/bin/clang ... \
		 -I/root/lib/perf/include/bpf ...
                             ^^^^^^^^^^^^
...
[root@p23lp27 perf]# ./perf test -F 40
40: BPF filter                                            :
40.1: Basic BPF filtering                                 : Ok
40.2: BPF pinning                                         : Ok
40.3: BPF prologue generation                             : Ok
40.4: BPF relocation checker                              : Ok

[root@p23lp27 perf]#

---
 tools/perf/Makefile.config | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index f5a3b402589e..67b042738ed7 100644
@@ -905,8 +905,8 @@ bindir = $(abspath $(prefix)/$(bindir_relative))
 mandir = share/man
 infodir = share/info
 perfexecdir = libexec/perf-core
-perf_include_dir = lib/include/perf
-perf_examples_dir = lib/examples/perf
+perf_include_dir = lib/perf/include
+perf_examples_dir = lib/perf/examples
 sharedir = $(prefix)/share
 template_dir = share/perf-core/templates
 STRACE_GROUPS_DIR = share/perf-core/strace/groups

2.17.0

Em Tue, Jul 31, 2018 at 09:32:54AM +0200, Thomas Richter escreveu:

So, testing it:

[root@jouet perf]# cat tools/perf/examples/bpf/5sec.c // SPDX-License-Identifier: GPL-2.0
/*
Description:

. Disable strace like syscall tracing (--no-syscalls), or try tracing
just some (-e *sleep).

. Attach a filter function to a kernel function, returning when it should
be considered, i.e. appear on the output.

. Run it system wide, so that any sleep of >= 5 seconds and < than 6
seconds gets caught.

. Ask for callgraphs using DWARF info, so that userspace can be unwound

. While this is running, run something like "sleep 5s".

. If we decide to add tv_nsec as well, then it becomes:

int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec)

I.e. add where it comes from (rqtp->tv_nsec) and where it will be accessible in the function body (nsec)

# perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/
0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5
hrtimer_nanosleep ([kernel.kallsyms]) __x64_sys_nanosleep ([kernel.kallsyms]) do_syscall_64 ([kernel.kallsyms]) entry_SYSCALL_64 ([kernel.kallsyms]) __GI___nanosleep (/usr/lib64/libc-2.26.so) rpl_nanosleep (/usr/bin/sleep) xnanosleep (/usr/bin/sleep) main (/usr/bin/sleep) __libc_start_main (/usr/lib64/libc-2.26.so) _start (/usr/bin/sleep)
^C#

Copyright (C) 2018 Red Hat, Inc., Arnaldo Carvalho de Melo <[email protected]>
*/

#include <bpf.h>

int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx, int err, long sec)

{
	return sec == 5;
}

license(GPL);
[root@jouet perf]# perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c

     0.000 perf_bpf_probe:hrtimer_nanosleep:(ffffffff9911efe0) tv_sec=5

3145.238 perf_bpf_probe:hrtimer_nanosleep:(ffffffff9911efe0) tv_sec=5
^C[root@jouet perf]#

After it works just the same, thanks, applying.

I need to get the above testing process hooked up in 'perf test', so that besides adding that -I/root/lib/perf/include/bpf we actually _try_ to include something from there from the /root/lib/perf/examples/bpf/ bpf example scripts.

- Arnaldo