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authorAndrew Waterman <andrew@sifive.com>2016-12-18 22:53:48 -0800
committerAlan Modra <amodra@gmail.com>2016-12-20 12:26:33 +1030
commit45f764234a71431b581340957a3c8338e0593fdb (patch)
tree15fdb770f8d357dde9e570452a2afed2ba0772d0 /include/elf
parent1d65abb5e2cb1624b358dda27a53a070bec685cc (diff)
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Rework RISC-V relocations
Before this commit we didn't cleanly support CFI directives because the internal offsets used to get relaxed which broke them. This patch significantly reworks how we handle linker relaxations: * DWARF is now properly supported * There is a ".option norelax" to disable relaxations, for when users write assembly that can't be relaxed (if it's to be later patched up, for example). * There is an additional _RELAX relocation that specifies when previous relocations can be relaxed. We're in the process of documenting the RISC-V ELF ABI, which will include documentation of our relocations https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md but we expect that this relocation set will remain ABI compatible in the future (ie, it's safe to release). Thanks to Kuan-Lin Chen for figuring out how to correctly relax the debug info! include/ * elf/riscv.h: Add R_RISCV_TPREL_I through R_RISCV_SET32. bfd/ * reloc.c (BFD_RELOC_RISCV_TPREL_I): New relocation. (BFD_RELOC_RISCV_TPREL_S): Likewise. (BFD_RELOC_RISCV_RELAX): Likewise. (BFD_RELOC_RISCV_CFA): Likewise. (BFD_RELOC_RISCV_SUB6): Likewise. (BFD_RELOC_RISCV_SET8): Likewise. (BFD_RELOC_RISCV_SET8): Likewise. (BFD_RELOC_RISCV_SET16): Likewise. (BFD_RELOC_RISCV_SET32): Likewise. * elfnn-riscv.c (perform_relocation): Handle the new relocations. (_bfd_riscv_relax_tls_le): Likewise. (_bfd_riscv_relax_align): Likewise. (_bfd_riscv_relax_section): Likewise. (howto_table): Likewise. (riscv_reloc_map): Likewise. (relax_func_t): New type. (_bfd_riscv_relax_call): Add reserve_size argument, which controls the maximal offset pessimism. Correct type of max_alignment. (_bfd_riscv_relax_lui): Likewise. (_bfd_riscv_relax_tls_le): Likewise. (_bfd_riscv_relax_align): Likewise. (_bfd_riscv_relax_section): Compute the required reserve size when relocating and use it to when calling relax_func. * bfd-in2.h: Regenerate. * libbfd.h: Likewise. gas/ * config/tc-riscv.c (riscv_set_options): Add relax. (riscv_opts): Likewise. (s_riscv_option): Add relax and norelax. (riscv_apply_const_reloc): New function. (append_insn): Move constant relocation handling to riscv_apply_const_reloc. (md_pcrel_from): Likewise. (parse_relocation): Skip BFD_RELOC_UNUSED. (md_pcrel_from): Handle BFD_RELOC_RISCV_SUB6, BFD_RELOC_RISCV_RELAX, BFD_RELOC_RISCV_CFA. (md_apply_fix): Likewise. (riscv_pre_output_hook): New function. * config/tc-riscv.h (md_pre_output_hook): Define. (riscv_pre_output_hook): Declare. (DWARF_CIE_DATA_ALIGNMENT): Always -4.
Diffstat (limited to 'include/elf')
-rw-r--r--include/elf/riscv.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/elf/riscv.h b/include/elf/riscv.h
index 8415659..4407611 100644
--- a/include/elf/riscv.h
+++ b/include/elf/riscv.h
@@ -79,6 +79,14 @@ START_RELOC_NUMBERS (elf_riscv_reloc_type)
RELOC_NUMBER (R_RISCV_RVC_LUI, 46)
RELOC_NUMBER (R_RISCV_GPREL_I, 47)
RELOC_NUMBER (R_RISCV_GPREL_S, 48)
+ RELOC_NUMBER (R_RISCV_TPREL_I, 49)
+ RELOC_NUMBER (R_RISCV_TPREL_S, 50)
+ RELOC_NUMBER (R_RISCV_RELAX, 51)
+ RELOC_NUMBER (R_RISCV_SUB6, 52)
+ RELOC_NUMBER (R_RISCV_SET6, 53)
+ RELOC_NUMBER (R_RISCV_SET8, 54)
+ RELOC_NUMBER (R_RISCV_SET16, 55)
+ RELOC_NUMBER (R_RISCV_SET32, 56)
END_RELOC_NUMBERS (R_RISCV_max)
/* Processor specific flags for the ELF header e_flags field. */