Re: elf: add livepatch-specific elf constants

[Jessica Yu]

+++ Josh Poimboeuf [12/11/15 09:45 -0600]:
> On Mon, Nov 09, 2015 at 11:45:51PM -0500, Jessica Yu wrote:
> > Add livepatch elf reloc section flag, livepatch symbol bind
> > and section index
> >
> > Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
> > ---
> >  include/uapi/linux/elf.h | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h
> > index 71e1d0e..967ce1b 100644
> > --- a/include/uapi/linux/elf.h
> > +++ b/include/uapi/linux/elf.h
> > @@ -118,6 +118,7 @@ typedef __s64	Elf64_Sxword;
> >  #define STB_LOCAL  0
> >  #define STB_GLOBAL 1
> >  #define STB_WEAK   2
> > +#define STB_LIVEPATCH_EXT 11
> >
> >  #define STT_NOTYPE  0
> >  #define STT_OBJECT  1
> > @@ -286,6 +287,7 @@ typedef struct elf64_phdr {
> >  #define SHF_ALLOC	0x2
> >  #define SHF_EXECINSTR	0x4
> >  #define SHF_MASKPROC	0xf0000000
> > +#define SHF_RELA_LIVEPATCH  0x4000000
>
> Writing the value with leading zeros (0x04000000) would it more
> readable.
>
> Also the OS-specific range mask (SHF_MASKOS) is 0x0ff00000.  Any reason
> you went with 0x04000000 as opposed to the first value in the range
> (0x00100000)?  I don't see anybody else using that value.

I don't have any particular reason, I think I just picked any value
and ran with it. I'll just change it to the first value in the range
since that makes more sense.

> >  /* special section indexes */
> >  #define SHN_UNDEF	0
> > @@ -295,6 +297,7 @@ typedef struct elf64_phdr {
> >  #define SHN_ABS		0xfff1
> >  #define SHN_COMMON	0xfff2
> >  #define SHN_HIRESERVE	0xffff
> > +#define SHN_LIVEPATCH 0xff21
>
> Similar question here, why not use 0xff20 (SHN_LOOS)?
>
> --
> Josh
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