Re: [PATCH] elf/elf.h: Add new 386 and X86_64 relocations from binutils.

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Jan 28, 2016 at 4:55 AM, Mark Wielaard <mjw@redhat.com> wrote:
> The following new 386 and X86_64 were added to binutils. They are
> non-dynamic relocations, so don't need direct handling in glibc.
> But other programs, like elfutils, use the glibc elf.h definitions
> for the names and numbers when inspecting ET_REL files.
>
> R_386_GOT32X was proposed in
> https://groups.google.com/forum/#!topic/ia32-abi/GbJJskkid4I
>
> X86_64_GOTPCRELX and R_X86_64_REX_GOTPCRELX were proposed in
> https://groups.google.com/forum/#!topic/x86-64-abi/n9AWHogmVY0
>
> There also used to be R_X86_64_PC32_BND (39) and R_X86_64_PLT32_BND (40)
> but those already got deprecated and now the numbers are simply reserved.

We can't use them for anything else and linker still supports them,  But
assembler won't generate them.

> See https://groups.google.com/d/msg/x86-64-abi/-hdQyMixt8Y/XFDOvioG85cJ
> They are still in current binutils master, but given that they should
> not be used I didn't add them to elf.h.
>
>         * elf/elf.h (R_386_GOT32X): New.
>         (R_386_NUM): Update.
>         (R_X86_64_GOTPCRELX: New.
>         (R_X86_64_REX_GOTPCRELX): New.
>         (R_X86_64_NUM): Update.
>
> OK to commit?
>
> ---
>
> diff --git a/elf/elf.h b/elf/elf.h
> index 15f5a75..1a7000b 100644
> --- a/elf/elf.h
> +++ b/elf/elf.h
> @@ -1269,8 +1269,10 @@ typedef struct
>                                            argument, returning the TLS
>                                            offset for the symbol.  */
>  #define R_386_IRELATIVE           42           /* Adjust indirectly by program base */
> +#define R_386_GOT32X      43           /* Load from 32 bit GOT entry,
> +                                          relaxable. */
>  /* Keep this the last entry.  */
> -#define R_386_NUM         43
> +#define R_386_NUM         44
>
>  /* SUN SPARC specific definitions.  */
>
> @@ -3144,8 +3146,15 @@ enum
>  #define R_X86_64_TLSDESC        36     /* TLS descriptor.  */
>  #define R_X86_64_IRELATIVE     37      /* Adjust indirectly by program base */
>  #define R_X86_64_RELATIVE64    38      /* 64-bit adjust by program base */
> -
> -#define R_X86_64_NUM           39
> +                                       /* 39 Reserved was R_X86_64_PC32_BND */
> +                                       /* 40 Reserved was R_X86_64_PLT32_BND */
> +#define R_X86_64_GOTPCRELX     41      /* Load from 32 bit signed pc relative
> +                                          offset to GOT entry without REX
> +                                          prefix, relaxable.  */
> +#define R_X86_64_REX_GOTPCRELX 42      /* Load from 32 bit signed pc relative
> +                                          offset to GOT entry with REX prefix,
> +                                          relaxable.  */
> +#define R_X86_64_NUM           43
>
>
>  /* AM33 relocations.  */
> --
> 1.8.3.1
>
Looks good to me.

Thanks.



-- 
H.J.