Re: [PATCH v1 6/7] perf trace: 5sec fix libbpf 1.0+ compatibility

[Arnaldo Carvalho de Melo]

Em Thu, Nov 03, 2022 at 12:39:59PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Nov 03, 2022 at 12:36:36PM -0300, Arnaldo Carvalho de Melo escreveu:
> > [root@quaco ~]# perf trace -e /home/acme/git/perf/tools/perf/examples/bpf/5sec.c
> > /home/acme/git/perf/tools/perf/examples/bpf/5sec.c:42:10: fatal error: 'bpf/bpf_helpers.h' file not found
> > #include <bpf/bpf_helpers.h>
> >          ^~~~~~~~~~~~~~~~~~~
> > 1 error generated.
> > ERROR:	unable to compile /home/acme/git/perf/tools/perf/examples/bpf/5sec.c
> > Hint:	Check error message shown above.
> > Hint:	You can also pre-compile it into .o using:
> >      		clang -target bpf -O2 -c /home/acme/git/perf/tools/perf/examples/bpf/5sec.c
> >      	with proper -I and -D options.
> > event syntax error: '/home/acme/git/perf/tools/perf/examples/bpf/5sec.c'
> >                      \___ Failed to load /home/acme/git/perf/tools/perf/examples/bpf/5sec.c from source: Error when compiling BPF scriptlet
> > 
> > (add -v to see detail)
> > Run 'perf list' for a list of valid events
> > 
> >  Usage: perf trace [<options>] [<command>]
> >     or: perf trace [<options>] -- <command> [<options>]
> >     or: perf trace record [<options>] [<command>]
> >     or: perf trace record [<options>] -- <command> [<options>]
> > 
> >     -e, --event <event>   event/syscall selector. use 'perf list' to list available events
> > [root@quaco ~]#
> > 
> > It is not even finding it, in this machine I have libbpf 0.7.0, so there
> > is a /usr/include/bpf/bpf_helpers.h, but probably that isn't in the
> > include path set up to build the tools/perf/examples/bpf/ files, perhaps
> > it should use:
> > 
> > -Itools/lib/  so that it gets tools/lib/bpf_helpers.h?
> > 
> > Trying to get this tested...
> 
> Running with -v:
> 
> llvm compiling command : /usr/lib64/ccache/clang -D__KERNEL__ -D__NR_CPUS__=8 -DLINUX_VERSION_CODE=0x51310 -g -I/home/acme/lib/perf/include/bpf -nostdinc -I./arch/x86/include -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/compiler-version.h -include ./include/linux/kconfig.h  -Wno-unused-value -Wno-pointer-sign -working-directory /lib/modules/5.19.16-200.fc36.x86_64/build -c /home/acme/git/perf/tools/perf/examples/bpf/5sec.c -target bpf  -g -O2 -o -
> /home/acme/git/perf/tools/perf/examples/bpf/5sec.c:42:10: fatal error: 'bpf/bpf_helpers.h' file not found
> 
> There is still that -I/home/acme/lib/perf/include/bpf, I'll remove it
> from the include path and try to replace it with the libbpf path...

Ok, works with the patch below, that needs some more renaming from "perf_" to
"libbpf_", etc:

[root@quaco ~]# perf trace -e /home/acme/git/perf/tools/perf/examples/bpf/5sec.c  sleep 5
     0.000 sleep/160828 perf_bpf_probe:hrtimer_nanosleep(__probe_ip: -1474734416, rqtp: 5000000000)
[root@quaco ~]#

Since I have:

[root@quaco ~]# cat ~/.perfconfig
[llvm]
	dump-obj = true
	clang-opt = -g
#

I end up with:

[root@quaco ~]# ls -la /home/acme/git/perf/tools/perf/examples/bpf/5sec.o
-rw-r--r--. 1 root root 3696 Nov  3 12:47 /home/acme/git/perf/tools/perf/examples/bpf/5sec.o
[root@quaco ~]# file /home/acme/git/perf/tools/perf/examples/bpf/5sec.o
/home/acme/git/perf/tools/perf/examples/bpf/5sec.o: ELF 64-bit LSB relocatable, eBPF, version 1 (SYSV), with debug_info, not stripped
[root@quaco ~]#

and can test with the pre-built .o eBPF bytecode + capped backtrace:

[root@quaco ~]# perf trace -e /home/acme/git/perf/tools/perf/examples/bpf/5sec.o/max-stack=6/  sleep 5
     0.000 sleep/161037 perf_bpf_probe:hrtimer_nanosleep(__probe_ip: -1474734416, rqtp: 5000000000)
                                       hrtimer_nanosleep ([kernel.kallsyms])
                                       common_nsleep ([kernel.kallsyms])
                                       __x64_sys_clock_nanosleep ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
                                       __GI___clock_nanosleep (/usr/lib64/libc.so.6)
[root@quaco ~]#

I'll test the other examples with these changes after I drive Pedro to
school and get back to the office.

- Arnaldo

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index d3d3c13a9f25b55c..067a6e56eeacc9fc 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -1239,7 +1239,7 @@ includedir = $(abspath $(prefix)/$(includedir_relative))
 mandir = share/man
 infodir = share/info
 perfexecdir = libexec/perf-core
-perf_include_dir = lib/perf/include
+perf_include_dir = /usr/include
 perf_examples_dir = lib/perf/examples
 sharedir = $(prefix)/share
 template_dir = share/perf-core/templates
diff --git a/tools/perf/util/llvm-utils.c b/tools/perf/util/llvm-utils.c
index 2dc7970074196ca8..a5cac85783d8711f 100644
--- a/tools/perf/util/llvm-utils.c
+++ b/tools/perf/util/llvm-utils.c
@@ -495,7 +495,7 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
 
 	snprintf(linux_version_code_str, sizeof(linux_version_code_str),
 		 "0x%x", kernel_version);
-	if (asprintf(&perf_bpf_include_opts, "-I%s/bpf", perf_include_dir) < 0)
+	if (asprintf(&perf_bpf_include_opts, "-I%s/", perf_include_dir) < 0)
 		goto errout;
 	force_set_env("NR_CPUS", nr_cpus_avail_str);
 	force_set_env("LINUX_VERSION_CODE", linux_version_code_str);