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

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Date:   Thu, 13 Oct 2016 15:16:43 -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, jolsa@...hat.com,
        peterz@...radead.org, Ingo Molnar <mingo@...nel.org>,
        anton@...abs.org, namhyung@...nel.org
Subject: Re: [PATCH 2/9] perf/jit: enable jitdump support without dwarf

Em Thu, Oct 13, 2016 at 03:59:36AM -0700, Stephane Eranian escreveu:
> From: Maciej Debski <maciejd@...gle.com>
> 
> This patch modifies the build dependencies on the jitdump
> support in perf. As it stands jitdump was wrongfully made dependent
> 100% on using DWARF. However, the dwarf dependency, only exist if
> generating the source line table in genelf_debug.c. The rest of the
> support does not need DWARF.
> 
> This patch removes the dependency on DWARF for the entire jitdump
> support. It keeps it only for the genelf_debug.c support.

Please add a:

Fixes: e12b202f8fb9 ("perf jitdump: Build only on supported archs")

Next time, so that scripts can pick patches for stable kernels, etc.

Adding it this time.

Thanks,

- Arnaldo

 
> Signed-off-by: Maciej Debski <maciejd@...gle.com>
> Reviewed-by: Stephane Eranian <eranian@...gle.com>
> ---
>  tools/perf/Makefile.config | 2 --
>  tools/perf/util/Build      | 2 +-
>  tools/perf/util/genelf.c   | 9 +++++++--
>  tools/perf/util/genelf.h   | 2 ++
>  4 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 72edf83d76b7..8cfc310d4358 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -366,10 +366,8 @@ ifndef NO_SDT
>  endif
>  
>  ifdef PERF_HAVE_JITDUMP
> -  ifndef NO_DWARF
>      $(call detected,CONFIG_JITDUMP)
>      CFLAGS += -DHAVE_JITDUMP
> -  endif
>  endif
>  
>  ifeq ($(ARCH),powerpc)
> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index eb60e613d795..1dc67efad634 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -120,7 +120,7 @@ libperf-y += demangle-rust.o
>  ifdef CONFIG_JITDUMP
>  libperf-$(CONFIG_LIBELF) += jitdump.o
>  libperf-$(CONFIG_LIBELF) += genelf.o
> -libperf-$(CONFIG_LIBELF) += genelf_debug.o
> +libperf-$(CONFIG_DWARF) += genelf_debug.o
>  endif
>  
>  CFLAGS_config.o   += -DETC_PERFCONFIG="BUILD_STR($(ETC_PERFCONFIG_SQ))"
> diff --git a/tools/perf/util/genelf.c b/tools/perf/util/genelf.c
> index c1ef805c6a8f..14a73acc549c 100644
> --- a/tools/perf/util/genelf.c
> +++ b/tools/perf/util/genelf.c
> @@ -19,7 +19,9 @@
>  #include <limits.h>
>  #include <fcntl.h>
>  #include <err.h>
> +#ifdef HAVE_DWARF_SUPPORT
>  #include <dwarf.h>
> +#endif
>  
>  #include "perf.h"
>  #include "genelf.h"
> @@ -157,7 +159,7 @@ gen_build_id(struct buildid_note *note, unsigned long load_addr, const void *cod
>  int
>  jit_write_elf(int fd, uint64_t load_addr, const char *sym,
>  	      const void *code, int csize,
> -	      void *debug, int nr_debug_entries)
> +	      void *debug __maybe_unused, int nr_debug_entries __maybe_unused)
>  {
>  	Elf *e;
>  	Elf_Data *d;
> @@ -386,11 +388,14 @@ jit_write_elf(int fd, uint64_t load_addr, const char *sym,
>  	shdr->sh_size = sizeof(bnote);
>  	shdr->sh_entsize = 0;
>  
> +#ifdef HAVE_DWARF_SUPPORT
>  	if (debug && nr_debug_entries) {
>  		retval = jit_add_debug_info(e, load_addr, debug, nr_debug_entries);
>  		if (retval)
>  			goto error;
> -	} else {
> +	} else
> +#endif
> +	{
>  		if (elf_update(e, ELF_C_WRITE) < 0) {
>  			warnx("elf_update 4 failed");
>  			goto error;
> diff --git a/tools/perf/util/genelf.h b/tools/perf/util/genelf.h
> index 2fbeb59c4bdd..5c933ac71451 100644
> --- a/tools/perf/util/genelf.h
> +++ b/tools/perf/util/genelf.h
> @@ -4,8 +4,10 @@
>  /* genelf.c */
>  int jit_write_elf(int fd, uint64_t code_addr, const char *sym,
>  		  const void *code, int csize, void *debug, int nr_debug_entries);
> +#ifdef HAVE_DWARF_SUPPORT
>  /* genelf_debug.c */
>  int jit_add_debug_info(Elf *e, uint64_t code_addr, void *debug, int nr_debug_entries);
> +#endif
>  
>  #if   defined(__arm__)
>  #define GEN_ELF_ARCH	EM_ARM
> -- 
> 1.9.1