[PATCH] fix Score absolute relocation on elf32 score

[Jan Beulich]

On 13.11.2024 17:49, 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

I'm afraid your response is confusing to me, as I know nothing about the
Score architecture. Looking at the opcode table I see quite a few insns
with a ! at the end. Yet there's no "j!" there.

In any event you will want to re-submit your bugfix with an explanation
added. The better the explanation, the more likely that someone like me
(not knowing the target) can approve the change.

A quick search didn't turn up any hits for an ELF psABI for the target,
so a pointer there may help, too.

Jan

> ________________________________
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 12 November 2024 09:18
> 
> 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);
>