[PATCH] fix Score absolute relocation on elf32 score

[Hans-Peter Nilsson]

On Wed, 13 Nov 2024, Danish Reyjavik wrote:
> There's a bug with binutils creating a jump instruction with 24bit jumps: there are many j
> instructions, one of which is 24bit offsets, so note what the fix does:
> - abs_value = value - rel_addr;
> + abs_value = (value < rel_addr) ? rel_addr - value : value - rel_addr;
> 
> that instruction is bugged when jumping backwards but most short j's will be converted to j!, so
> it went unnoticed

Just some random advice from the sideline: a testcase, even 
better, one in the form of an added regression test, to the 
score part of the (gas or ld as appropriate) testsuite, says 
more than any number of words.  It also helps agains accidental 
misedits of the code.

brgds, H-P

> 
> ________________________________________________________________________________________________
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 12 November 2024 09:18
> To: Danish Reyjavik <danishreyjavik@outlook.com>
> Cc: binutils@sourceware.org <binutils@sourceware.org>
> Subject: Re: [PATCH] fix Score absolute relocation on elf32 score
> On 11.11.2024 19:43, Danish Reyjavik wrote:
> > diff --git a/bfd/elf32-score.c b/bfd/elf32-score.c
> > index d1a910f279..eb93c7cfa1 100644
> 
> I'm not a maintainer of the given target (and sadly there also is no-one
> named to play that role), so I can't say anything about the correctness.
> In particular as long as such a change comes with no description at all.
> 
> Jan
> 
> > --- bfd/elf32-score.c
> > +++ bfd/elf32-score.c
> > @@ -2165,7 +2165,7 @@ score_elf_final_link_relocate (reloc_howto_type *howto,
> > if ((offset & 0x1000000) != 0)
> > ?????offset |= 0xfe000000;
> > value += offset;
> > - abs_value = value - rel_addr;
> > + abs_value = (value < rel_addr) ? rel_addr - value : value - rel_addr;
> > if ((abs_value & 0xfe000000) != 0)
> > ?????return bfd_reloc_overflow;
> > addend = (addend & ~howto->src_mask)
> > @@ -2241,7 +2241,7 @@ score_elf_final_link_relocate (reloc_howto_type *howto,
> > if ((offset & 0x800) != 0)???/* Offset is negative. */
> > ?????offset |= 0xfffff000;
> > value += offset;
> > - abs_value = value - rel_addr;
> > + abs_value = (value < rel_addr) ? rel_addr - value : value - rel_addr;
> > if ((abs_value & 0xfffff000) != 0)
> > ?????return bfd_reloc_overflow;
> > addend = (addend & ~howto->src_mask) | (value & howto->src_mask);
> > diff --git a/bfd/elf32-score7.c b/bfd/elf32-score7.c
> > index ab5e32a29a..3bf4c30465 100644
> > --- bfd/elf32-score7.c
> > +++ bfd/elf32-score7.c
> > @@ -2066,7 +2066,7 @@ score_elf_final_link_relocate (reloc_howto_type *howto,
> > if ((offset & 0x1000000) != 0)
> > ?????offset |= 0xfe000000;
> > value += offset;
> > - abs_value = value - rel_addr;
> > + abs_value = (value < rel_addr) ? rel_addr - value : value - rel_addr;
> > if ((abs_value & 0xfe000000) != 0)
> > ?????return bfd_reloc_overflow;
> > addend = (addend & ~howto->src_mask)
> > @@ -2096,7 +2096,7 @@ score_elf_final_link_relocate (reloc_howto_type *howto,
> > if ((offset & 0x800) != 0)???/* Offset is negative. */
> > ?????offset |= 0xfffff000;
> > value += offset;
> > - abs_value = value - rel_addr;
> > + abs_value = (value < rel_addr) ? rel_addr - value : value - rel_addr;
> > if ((abs_value & 0xfffff000) != 0)
> > ?????return bfd_reloc_overflow;
> > addend = (addend & ~howto->src_mask) | (value & howto->src_mask);
> 
> 
>