[PATCH] fix Score absolute relocation on elf32 score

[Danish Reyjavik]

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
________________________________
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);

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