[PATCH] ldso - adding HAVE_RELATIVE_RELOCS define

Carmelo Amoroso carmelo73 at gmail.com
Tue Jan 6 07:26:31 UTC 2009


olsajiri at gmail.com wrote:
> As the former comment suggested, I added the HAVE_RELATIVE_RELOCS and
> and reduced the linker code size.
> 
>  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
> -[ 6] .text             PROGBITS        00000a2c 000a2c 00323e 00  AX  0   0  4
> +[ 6] .text             PROGBITS        00000a2c 000a2c 003133 00  AX  0   0  4
> 
> I suppose most of the linkers support -Bsymbolic,
> but I could verify only i386 and arm. 
> 
> Signed-off-by: Jiri Olsa <olsajiri at gmail.com>

Hi,
cool this patch was missing since a long time, thanks for posting.
Just a comment: probably the HAVE_RELATIVE_RELOCS macro should be defined
in the dl-sysdeps.h header.

cheers,
carmelo
> ---
> Index: ldso/ldso/arm/dl-startup.h
> ===================================================================
> --- ldso/ldso/arm/dl-startup.h	(revision 24692)
> +++ ldso/ldso/arm/dl-startup.h	(working copy)
> @@ -135,6 +135,9 @@
>   * do something a little more subtle here.  */
>  #define GET_ARGV(ARGVP, ARGS) ARGVP = (((unsigned long*)ARGS)+1)
>  
> +/* The linker supports relative relocations. */
> +#define HAVE_RELATIVE_RELOCS
> +
>  /* Handle relocation of the symbols in the dynamic loader. */
>  static __always_inline
>  void PERFORM_BOOTSTRAP_RELOC(ELF_RELOC *rpnt, unsigned long *reloc_addr,
> Index: ldso/ldso/dl-startup.c
> ===================================================================
> --- ldso/ldso/dl-startup.c	(revision 24692)
> +++ ldso/ldso/dl-startup.c	(working copy)
> @@ -250,16 +250,18 @@
>  			if (!rel_addr)
>  				continue;
>  
> -			/* Now parse the relocation information */
> -			/* Since ldso is linked with -Bsymbolic, all relocs will be RELATIVE(for those archs that have
> -			   RELATIVE relocs) which means that the for(..) loop below has nothing to do and can be deleted.
> -			   Possibly one should add a HAVE_RELATIVE_RELOCS directive and #ifdef away some code. */
>  			if (!indx && relative_count) {
>  				rel_size -= relative_count * sizeof(ELF_RELOC);
>  				elf_machine_relative(load_addr, rel_addr, relative_count);
>  				rel_addr += relative_count * sizeof(ELF_RELOC);
>  			}
>  
> +			/* Since ldso is linked with -Bsymbolic, all relocs will be RELATIVE (for those archs that have
> +			   RELATIVE relocs - HAVE_RELATIVE_RELOCS define).  Which means that the for(..) loop below has 
> +			   nothing to do and can omited. */
> +#if !defined(HAVE_RELATIVE_RELOCS)
> +
> +			/* Now parse the relocation information */
>  			rpnt = (ELF_RELOC *) rel_addr;
>  			for (i = 0; i < rel_size; i += sizeof(ELF_RELOC), rpnt++) {
>  				reloc_addr = (unsigned long *) DL_RELOC_ADDR(load_addr, (unsigned long)rpnt->r_offset);
> @@ -285,6 +287,7 @@
>  				/* Use this machine-specific macro to perform the actual relocation.  */
>  				PERFORM_BOOTSTRAP_RELOC(rpnt, reloc_addr, symbol_addr, load_addr, sym);
>  			}
> +#endif // !defined(HAVE_RELATIVE_RELOCS)
>  		}
>  	}
>  #endif
> Index: ldso/ldso/i386/dl-startup.h
> ===================================================================
> --- ldso/ldso/i386/dl-startup.h	(revision 24692)
> +++ ldso/ldso/i386/dl-startup.h	(working copy)
> @@ -39,6 +39,9 @@
>   * do something a little more subtle here.  */
>  #define GET_ARGV(ARGVP, ARGS) ARGVP = (((unsigned long*) & ARGS)+1)
>  
> +/* The linker supports relative relocations. */
> +#define HAVE_RELATIVE_RELOCS
> +
>  /* Handle relocation of the symbols in the dynamic loader. */
>  static __always_inline
>  void PERFORM_BOOTSTRAP_RELOC(ELF_RELOC *rpnt, unsigned long *reloc_addr,
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