The bpf reloc howtos are a bit weird, using bitpos to specify an
offset from r_offset that is outside the size of the reloc as given by
howto.size. That means bfd_get_reloc_size gives the wrong answer for
range checking, and thus bfd_reloc_offset_in_range can't be used.
* elf64-bpf.c (bpf_elf_generic_reloc): Handle bitpos offset reloc
range checking.
The testcase in this PR tickled two bugs fixed here. output_bfd is
NULL when a reloc special_function is called for final linking and
when called from bfd_generic_get_relocated_section_contents. Clearly
using output_bfd is wrong as it results in segfaults. Not only that,
the endianness of the reloc field really should be that of the input.
The second bug was not checking that the entire reloc field was
contained in the section contents.
PR 28055
* elf64-bpf.c (bpf_elf_generic_reloc): Use correct bfd for bfd_put
and bfd_put_32 calls. Correct section limit checks.
When performing DISP{16,32} relocations, the eBPF ELF backend linker
needs to convert the relocation from an address into a signed number
of 64-bit words (minus one) to jump.
Because of this unsigned-to-signed conversion, special care needs to
be taken when dividing to ensure the sign bits remain correct.
Otherwise, a false relocation overflow error can be triggered.
bfd/ChangeLog
2020-08-07 David Faust <david.faust@oracle.com>
* elf64-bpf.c (bpf_elf_relocate_section): Ensure signed division for
DISP16 and DISP32 relocations.
ld/ChangeLog
2020-08-07 David Faust <david.faust@oracle.com>
* testsuite/ld-bpf/call-3.s: New file.
* testsuite/ld-bpf/call-3.d: Likewise.
The eBPF ELF backend was not properly recording relocation addends
during installation, nor reading and applying them when performing
the final relocation. This lead to various issues with incorrect
relocations.
These issues are fixed with a new howto special function to install
the relocations, and updates to bpf_elf_relocate_section to read and
use the addends as recorded in the input_bfd.
bfd/ChangeLog
2020-08-05 David Faust <david.faust@oracle.com>
* elf64-bpf.c (bpf_elf_generic_reloc): New function.
(bpf_elf_howto_table): Use it here.
(bpf_elf_relocate_section): Use addends recorded in input_bfd for
instruction and data relocations.
ld/ChangeLog
2020-08-05 David Faust <david.faust@oracle.com>
* testsuite/ld-bpf/call-2.s: New file.
* testsuite/ld-bpf/call-2.d: Likewise.
* testsuite/ld-bpf/reloc-data-be.d: Likewise.
* testsuite/ld-bpf/reloc-data-le.d: Likewise.
* testsuite/ld-bpf/reloc-data.s: Likewise.
* testsuite/ld-bpf/reloc-insn-external-be.d: Likewise.
* testsuite/ld-bpf/reloc-insn-external-le.d: Likewise.
* testsuite/ld-bpf/reloc-insn-external.s: Likewise.
* testsuite/ld-bpf/reloc-insn32-be.d: Likewise.
* testsuite/ld-bpf/reloc-insn32-le.d: Likewise.
* testsuite/ld-bpf/reloc-insn32.s: Likewise.
* testsuite/ld-bpf/reloc-insn64-be.d: Likewise.
* testsuite/ld-bpf/reloc-insn64-le.d: Likewise.
* testsuite/ld-bpf/reloc-insn64.s: Likewise.
This patch changes the eBPF linker to provide a relocate_section
function instead of relying on using special functions in relocation
howtos.
Tested in x86_64 host.
No regressions.
bfd/ChangeLog:
2019-08-07 Jose E. Marchesi <jose.marchesi@oracle.com>
* elf64-bpf.c (bpf_elf_relocate_section): New function.
(bpf_elf_insn_disp_reloc): Delete function.
(elf_backend_relocate_section): Define.