On 03/24/2016 02:20 PM, David Miller wrote:
> From: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
> Date: Wed, 23 Mar 2016 17:41:07 -0500
>
>> + /* If the section has relocations, we must read it ourselves.
>> +- Otherwise we attach it to the BFD. */
>> ++ Otherwise we attach it to the BFD.
>> ++ Also, in sparc64 only try mmap for sections which
>> ++ are properly aligned in order to avoid SIGBUS errors. */
>> ++
>> ++#if defined(__sparc__) && __WORDSIZE == 64
>> ++ if (info->size > 4 * pagesize && (sectp->flags & SEC_RELOC) == 0 && !(sectp->filepos & 0x3))
>> ++#else
>> + if ((sectp->flags & SEC_RELOC) == 0)
>> ++#endif
>> + {
>> + const gdb_byte *bytes = gdb_bfd_map_section (sectp, &info->size);
>
> This doesn't make any sense at all.
>
> The bug is probably that unaligned relocations are being improperly
> accessed using 32-bit loads and storess them.
>
> Several relocs, particularly those used in debugging sections, need to
> be carefully accessed using byte at a time accesses in order to avoid
> said SIGBUS problem.
>
> BFD and the rest of binutils have code to handle this case properly.
>
> Please don't paper over the core issue with hacks like this.
I have to admit that I don't know the whole story here. I took over the
crash port, but haven't had to touch the gdb patch that got handed to
me. What I do know is crash works off an older 7.6 branch of gdb. I'll
get back to you after I talk to some other folks.
Thanks,
Dave
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