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Re: [PATCH] perf jit: genelf makes assumptions about endian

From Arnaldo Carvalho de Melo <acme@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH] perf jit: genelf makes assumptions about endian
Date 2016-03-30 23:20 +0200
Message-ID <rivGV-2PT-5@gated-at.bofh.it> (permalink)
References <rhVWO-2De-21@gated-at.bofh.it> <ried4-7fJ-9@gated-at.bofh.it>
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Em Wed, Mar 30, 2016 at 01:38:20PM +1100, Michael Ellerman escreveu:
> On Tue, 2016-03-29 at 17:59 +1100, Anton Blanchard wrote:
> 
> > Commit 9b07e27f88b9 ("perf inject: Add jitdump mmap injection support")
> > incorrectly assumed that PowerPC is big endian only.
> > 
> > Simplify things by consolidating the define of GEN_ELF_ENDIAN and checking
> > for __BYTE_ORDER == __BIG_ENDIAN.
> > 
> > The PowerPC checks were also incorrect, they do not match what gcc
> > emits. We should first look for __powerpc64__, then __powerpc__.
> > 
> > Fixes: 9b07e27f88b9 ("perf inject: Add jitdump mmap injection support")
> > Signed-off-by: Anton Blanchard <anton@samba.org>
> 
> The diff's a little hard to read because you're pulling the endian logic out,
> if I remove that I get something like:

Yeah, I'm taking this patch, but would be better next time to break it
down in two, one doing the reorg, the other doing the actual fix...

Thanks,

- Arnaldo
 
> >  #elif defined(__i386__)
> >  #define GEN_ELF_ARCH	EM_386
> >  #define GEN_ELF_CLASS	ELFCLASS32
> > -#elif defined(__ppcle__)
> > -#define GEN_ELF_ARCH	EM_PPC
> > -#define GEN_ELF_CLASS	ELFCLASS64
> > -#elif defined(__powerpc__)
> > -#define GEN_ELF_ARCH	EM_PPC64
> > -#define GEN_ELF_CLASS	ELFCLASS64
> > -#elif defined(__powerpcle__)
> > +#elif defined(__powerpc64__)
> >  #define GEN_ELF_ARCH	EM_PPC64
> >  #define GEN_ELF_CLASS	ELFCLASS64
> > +#elif defined(__powerpc__)
> > +#define GEN_ELF_ARCH	EM_PPC
> > +#define GEN_ELF_CLASS	ELFCLASS32
> >  #else
> >  #error "unsupported architecture"
> >  #endif
> 
> Which looks correct to me.
> 
> And the consolidation of the endian logic is "obviously correct", so:
> 
> Acked-by: Michael Ellerman <mpe@ellerman.id.au>
> 
> cheers

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Thread

[PATCH] perf jit: genelf makes assumptions about endian Anton Blanchard <anton@samba.org> - 2016-03-29 09:10 +0200
  Re: [PATCH] perf jit: genelf makes assumptions about endian Michael Ellerman <mpe@ellerman.id.au> - 2016-03-30 04:40 +0200
    Re: [PATCH] perf jit: genelf makes assumptions about endian Arnaldo Carvalho de Melo <acme@redhat.com> - 2016-03-30 23:20 +0200
  [tip:perf/urgent] perf jit: genelf makes assumptions about endian tip-bot for Anton Blanchard <tipbot@zytor.com> - 2016-03-31 08:40 +0200

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