Re: [patch] Fix l_addr comment

[Jakub Jelinek <jakub at redhat dot com>]

On Fri, Sep 30, 2011 at 04:41:39PM +0200, Jan Kratochvil wrote:
> there is confusion what does l_addr mean as on systems without prelink it has
> the value which the comment describes.  But with prelink it is not the case:
> 
> (gdb) p *_r_debug.r_map.l_next.l_next
> $5 = {l_addr = 0, l_name = 0x7ffff7ffd740 "/lib64/libreadline.so.6", l_ld = 0x3f1d83bf90, l_next = 0x7ffff7fd3000, l_prev = 0x3f15420818}
>                ^

Not sure if talking about prelink there is desirable, l_addr
is simply a load bias, difference between l_map_start and first
PT_LOAD segment's virtual address in the ELF file.

> 2011-09-30  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
> 	* elf/link.h (struct link_map): Extend the l_addr comment.
> 	* include/link.h (struct link_map): Likewise.
> 
> --- a/elf/link.h
> +++ b/elf/link.h
> @@ -87,7 +87,12 @@ struct link_map
>      /* These first few members are part of the protocol with the debugger.
>         This is the same format used in SVR4.  */
>  
> -    ElfW(Addr) l_addr;		/* Base address shared object is loaded at.  */
> +    ElfW(Addr) l_addr;		/* Base address shared object is loaded at
> +				   minus where the object is prelinked to.
> +				   For successfully prelinked objects it is 0,
> +				   for non-prelinked objects it is its base
> +				   address.  It can be also anything else for
> +				   prelinked objects loaded elsewhere.  */ 
>      char *l_name;		/* Absolute file name object was found in.  */
>      ElfW(Dyn) *l_ld;		/* Dynamic section of the shared object.  */
>      struct link_map *l_next, *l_prev; /* Chain of loaded objects.  */
> --- a/include/link.h
> +++ b/include/link.h
> @@ -88,7 +88,12 @@ struct link_map
>      /* These first few members are part of the protocol with the debugger.
>         This is the same format used in SVR4.  */
>  
> -    ElfW(Addr) l_addr;		/* Base address shared object is loaded at.  */
> +    ElfW(Addr) l_addr;		/* Base address shared object is loaded at
> +				   minus where the object is prelinked to.
> +				   For successfully prelinked objects it is 0,
> +				   for non-prelinked objects it is its base
> +				   address.  It can be also anything else for
> +				   prelinked objects loaded elsewhere.  */ 
>      char *l_name;		/* Absolute file name object was found in.  */
>      ElfW(Dyn) *l_ld;		/* Dynamic section of the shared object.  */
>      struct link_map *l_next, *l_prev; /* Chain of loaded objects.  */

	Jakub