This is the mail archive of the binutils@sourceware.org mailing list for the binutils project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [Patch, avr] Fix PR 20221 - adjust syms and relocs only if relax shrunk section


2016-06-08 11:53 GMT+03:00 Senthil Kumar Selvaraj
<senthil_kumar.selvaraj@atmel.com>:
> Hi,
>
>   This patch fixes an edge case in linker relaxation that causes symbol
>   values to be computed incorrectly in the presence of align directives
>   in input source code.
>
>   As the below testcase demonstrates, for code like
>
> _start:
>         CALL    dest
>         .align  1
> dest:
>         NOP
>
>   where the bytes to be deleted (CALL to RCALL, 2 bytes) are adjacent to an
>   alignment boundary, no deletion happens - the prop record handling
>   merely overwrites the to-be-deleted-bytes with NOPs. AFAICT, this is
>   ok - eventually, relaxation sees that the padding is unnecessary and
>   strips the NOPs away.
>
>   However, the rest of elf32_avr_relax_delete_bytes runs with the assumption
>   that the bytes have been deleted, and this causes symbol values and/or
>   reloc offsets to be decremented even if nothing has moved. dest, in the
>   above testcase, gets decremented by 2 even when the gap got alignment
>   padded, and then again when the padding was removed - it ends up
>   getting adjusted down twice.
>
>   The patch fixes this by recording whether shrinking actually occurred,
>   and then skipping the reloc offset/sym value adjutment if it did
>   not. There's also a testcase that fails with master (and 2.26) that
>   passes with this patch.
>
>   Ok for master? Can I backport to 2.26 branch if ok?
>
> Regards
> Senthil
>
>
> bfd/ChangeLog
>
> 2016-06-08  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
>
>         PR ld/20221
>         * elf32-avr.c (elf32_avr_relax_delete_bytes): Adjust syms
>   and relocs only if shrinking occurred.
>
> ld/ChangeLog
>
> 2016-06-08  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
>
>         PR ld/20221
>         * testsuite/ld-avr/avr-prop-5.d: New.
>         * testsuite/ld-avr/avr-prop-5.s: New.
>
>

Committed.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]