linux-kernel - Re: [PATCH 2/9] perf/jit: enable jitdump support without dwarf

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Date:   Thu, 13 Oct 2016 16:44:15 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Maciej Debski <maciejd@...gle.com>
Cc:     Stephane Eranian <eranian@...gle.com>,
        linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Anton Blanchard <anton@...abs.org>,
        Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH 2/9] perf/jit: enable jitdump support without dwarf

Em Thu, Oct 13, 2016 at 04:03:11PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Thu, Oct 13, 2016 at 03:51:35PM -0300, Arnaldo Carvalho de Melo escreveu:
> > So we need:
> > 
> > [acme@...et linux]$ git diff
> > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > index 8cfc310d4358..cffdd9cf3ebf 100644
> > --- a/tools/perf/Makefile.config
> > +++ b/tools/perf/Makefile.config
> > @@ -366,8 +366,10 @@ ifndef NO_SDT
> >  endif
> >  
> >  ifdef PERF_HAVE_JITDUMP
> > +  ifndef NO_LIBELF
> >      $(call detected,CONFIG_JITDUMP)
> >      CFLAGS += -DHAVE_JITDUMP
> > +  endif
> >  endif
> >  
> >  ifeq ($(ARCH),powerpc)
> > [acme@...et linux]$ 
> > 
> > To get that fixed.
> > 
> > Please let me know if this suits your needs.
> > 
> > I'll now try building with elfutils static libraries to see if in that case it
> > all gets linked.
> 
> After installing these packages, on fedora, i.e. installing what is
> needed to statically link against libelf:
> 
>   elfutils-devel-static
>   elfutils-libelf-devel-static
>   zlib-static
> 
> Then it all works, libelf is statically linked and we also statically
> link the jitdump code:
> 
>   $ make -C tools/perf LDFLAGS=-static O=/tmp/build/perf install-bin
>   $ grep libelf /tmp/build/perf/FEATURE-DUMP 
>   feature-libelf=1
>   feature-libelf-getphdrnum=1
>   feature-libelf-gelf_getnote=1
>   feature-libelf-getshdrstrndx=1
>   feature-libelf-mmap=1
>   $
>   
> And:
> 
> [acme@...et linux]$ size /tmp/build/perf/perf
>    text	   data	    bss	    dec	    hex	filename
> 4478822	 581702	23919240	28979764	1ba3234	/tmp/build/perf/perf
> [acme@...et linux]$ 
> [acme@...et linux]$ file /tmp/build/perf/perf
> /tmp/build/perf/perf: ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), statically linked, for GNU/Linux 2.6.32, BuildID[sha1]=c2950590a0f24d76baa0ce4896414e5d523fefba, not stripped
> [acme@...et linux]$ 
> [acme@...et linux]$ nm /tmp/build/perf/perf | grep jit
> 00000000005007f0 T jit_process
> 0000000000501920 T jit_write_elf
> 0000000000431a50 t perf_event__jit_repipe_mmap
> 0000000000431b20 t perf_event__jit_repipe_mmap2
> [acme@...et linux]$ 

Ok, now this cset is bisected as causing this problem when built on Alpine Linux 3.4:

  CC       /tmp/build/perf/util/demangle-java.o
  CC       /tmp/build/perf/util/demangle-rust.o
  CC       /tmp/build/perf/util/jitdump.o
  CC       /tmp/build/perf/util/genelf.o
util/jitdump.c: In function 'jit_process':
util/jitdump.c:622:3: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]
   fprintf(stderr, "injected: %s (%d)\n", path, ret);
   ^
util/jitdump.c:584:6: note: 'ret' was declared here
  int ret;
      ^
  FLEX     /tmp/build/perf/util/parse-events-flex.c


/ $ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-alpine-linux-musl/5.3.0/lto-wrapper
Target: x86_64-alpine-linux-musl
Configured with: /home/buildozer/aports/main/gcc/src/gcc-5.3.0/configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --build=x86_64-alpine-linux-musl --host=x86_64-alpine-linux-musl --target=x86_64-alpine-linux-musl --with-pkgversion='Alpine 5.3.0' --enable-checking=release --disable-fixed-point --disable-libstdcxx-pch --disable-multilib --disable-nls --disable-werror --disable-symvers --enable-__cxa_atexit --enable-esp --enable-cloog-backend --enable-languages=c,c++,objc,java,fortran,ada --disable-libssp --disable-libmudflap --disable-libsanitizer --enable-shared --enable-threads --enable-tls --with-system-zlib
Thread model: posix
gcc version 5.3.0 (Alpine 5.3.0) 
/ $

Investigating...

- Arnaldo