Re: [PATCH] tools lib bpf: Use official ELF e_machine value

[Wangnan (F)]

Hi Arnaldo,

Please don't forget this patch.

Thank you.

On 2016/7/19 5:37, Alexei Starovoitov wrote:
> On Mon, Jul 18, 2016 at 06:01:08AM +0000, Wang Nan wrote:
> > New LLVM will issue newly assigned EM_BPF machine code. The new code
> > will be propogated to glibc and libelf.
> >
> > This patch introduces the new machine code to libbpf.
> >
> > Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> > Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> > Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > Cc: Zefan Li <lizefan@xxxxxxxxxx>
> > Cc: pi3orama@xxxxxxx
> > ---
> >   tools/lib/bpf/libbpf.c | 7 ++++++-
> >   1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index 32e6b6b..b699aea 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -37,6 +37,10 @@
> >   #include "libbpf.h"
> >   #include "bpf.h"
> >   
> > +#ifndef EM_BPF
> > +#define EM_BPF 247
> > +#endif
> > +
> >   #define __printf(a, b)	__attribute__((format(printf, a, b)))
> >   
> >   __printf(1, 2)
> > @@ -439,7 +443,8 @@ static int bpf_object__elf_init(struct bpf_object *obj)
> >   	}
> >   	ep = &obj->efile.ehdr;
> >   
> > -	if ((ep->e_type != ET_REL) || (ep->e_machine != 0)) {
> > +	/* Old LLVM set e_machine to EM_NONE */
> > +	if ((ep->e_type != ET_REL) || (ep->e_machine && (ep->e_machine != EM_BPF))) {
> Thanks for the fix. Didn't realize we already check for zero here.
> btw EM_BPF will be in llvm 3.9 release.
>
> Acked-by: Alexei Starovoitov <ast@xxxxxxxxxx>