[PATCH] perf s390: always build with -fPIC

[PATCH] perf s390: always build with -fPIC

[Hendrik Brueckner]

On s390, object files must be compiled with position-indepedent code
in order to be incrementally linked or linked to shared libraries.
Therefore, add -fPIC to the CFLAGS for s390 to ensure each object
file is built properly.

Reported-by: Jonathan Hermann <jonathan.hermann@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
---
 tools/perf/Makefile.config | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index ed65e82..0833d9f 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -55,6 +55,7 @@ endif
 
 ifeq ($(ARCH),s390)
   NO_PERF_REGS := 0
+  CFLAGS += -fPIC
 endif
 
 ifeq ($(NO_PERF_REGS),0)
-- 
1.8.3.1

Re: [PATCH] perf s390: always build with -fPIC

[Namhyung Kim]

(+ Jiri)

Hello,

On Thu, Nov 30, 2017 at 09:49:25AM +0100, Hendrik Brueckner wrote:
> On s390, object files must be compiled with position-indepedent code
> in order to be incrementally linked or linked to shared libraries.
> Therefore, add -fPIC to the CFLAGS for s390 to ensure each object
> file is built properly.

Could you please tell me what was the actual problem?  I guess this is
somewhat related to the Jiri's Fedora build fix.

Thanks,
Namhyung


> 
> Reported-by: Jonathan Hermann <jonathan.hermann@de.ibm.com>
> Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
> ---
>  tools/perf/Makefile.config | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index ed65e82..0833d9f 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -55,6 +55,7 @@ endif
>  
>  ifeq ($(ARCH),s390)
>    NO_PERF_REGS := 0
> +  CFLAGS += -fPIC
>  endif
>  
>  ifeq ($(NO_PERF_REGS),0)
> -- 
> 1.8.3.1
> 
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Re: [PATCH] perf s390: always build with -fPIC

[Hendrik Brueckner]

Hi Namhyung,

On Fri, Dec 01, 2017 at 11:17:09AM +0900, Namhyung Kim wrote:
> On Thu, Nov 30, 2017 at 09:49:25AM +0100, Hendrik Brueckner wrote:
> > On s390, object files must be compiled with position-indepedent code
> > in order to be incrementally linked or linked to shared libraries.
> > Therefore, add -fPIC to the CFLAGS for s390 to ensure each object
> > file is built properly.
> 
> Could you please tell me what was the actual problem?  I guess this is
> somewhat related to the Jiri's Fedora build fix.

Building, linking of perf did not work (I think it was on a Fedora 27)
resulting in an error message like:

/usr/bin/ld: perf-in.o: `__printf_chk@@GLIBC_2.4' non-PLT reloc for symbol
defined in shared library and accessed from executable (rebuild file with
-fPIC ?)
/usr/bin/ld: final link failed: Bad value

On s390, objects must be compiled with -fPIC when used for shared object
or position-indendepent executables (PIE). In doubt, it is better to
build with -fPIC (there are no performance degration).

Thanks and kind regards,
  Hendrik