Re: R_ARM_REL32 relocation patch

On Tue, Jul 28, 2009 at 04:13:50PM -0500, Nitin Garg wrote:
> I did google it around, also tried the workaround but that's still a
> workaround I beleive. Eventually this has to be handled in the kernel.
> Pls review, Thanks,
> 
> --- a/arch/arm/kernel/module.c  2009-07-20 16:57:49.000000000 -0500
> +++ b/arch/arm/kernel/module.c  2009-07-28 14:13:06.000000000 -0500
> @@ -132,6 +132,11 @@ apply_relocate(Elf32_Shdr *sechdrs, cons
>                         *(u32 *)loc += sym->st_value;
>                         break;
> 
> +               case R_ARM_REL32:
> +                       offset = *(u32 *)loc + sym->st_value - loc;
> +                       *(u32 *)loc = offset & 0xffffffff;
> +                       break;
> +

You shouldn't need to do offset & 0xffffffff, that's the natural size
of an u32.

I think this could be re-written as:

	*(u32 *)loc += (sym->st_value - loc) * 4;


                  case R_ARM_PC24:
>                 case R_ARM_CALL:
>                 case R_ARM_JUMP24:
> --- a/arch/arm/include/asm/elf.h        2009-07-20 16:57:49.000000000 -0500
> +++ b/arch/arm/include/asm/elf.h        2009-07-28 10:45:41.000000000 -0500
> @@ -48,6 +48,7 @@ typedef struct user_fp elf_fpregset_t;
>  #define R_ARM_NONE             0
>  #define R_ARM_PC24             1
>  #define R_ARM_ABS32            2
> +#define R_ARM_REL32             3
>  #define R_ARM_CALL             28
>  #define R_ARM_JUMP24           29
>  #define R_ARM_V4BX             40
> 
> 
> On Tue, Jul 28, 2009 at 3:13 PM, Ben Dooks<[email protected]> wrote:
> > On Tue, Jul 28, 2009 at 02:58:26PM -0500, Nitin Garg wrote:
> >> Hi All,
> >>
> >> Pls review the attached patch for R_ARM_REL32 relocation handling.
> >> Binutils 2.19.1 is adding the eh frame and hence we need to handle
> >> R_ARM_REL32 for Loadable kernel modules.
> >>
> >> Thanks,
> >> Nitin
> >
> > Please send patches inline so they can be reviewed (ie, turn up in
> > the reply).
> >
> > Some simple looking around on google shows it may be easier to avoid
> > generating these in the first place:
> >
> > http://forums.arm.com/index.php?s=766f87b528acd6be708a84cf3a58c02c&showtopic=8122&mode=threaded&pid=32358
> >
> > --
> > Ben
> >
> > Q:      What's a light-year?
> > A:      One-third less calories than a regular year.
> >
> >
> 
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-- 
-- 
Ben

Q:      What's a light-year?
A:      One-third less calories than a regular year.


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