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9abcdc10b2
Commitabd20cb637andebdcad3fddintroduced additional complexity into the paths run by the RISC-V relaxation pass in order to resolve the issue of accurately keeping track of pcrel_hi and pcrel_lo pairs. The first commit split up relaxation of these relocs into a pass which occurred after other relaxations in order to prevent the situation where bytes were deleted in between a pcrel_lo/pcrel_hi pair, inhibiting our ability to find the corresponding pcrel_hi relocation from the address attached to the pcrel_lo. Since the relaxation was split into two passes the 'again' parameter could not be used to perform the entire relaxation process again and so the second commit added a way to restart ldelf_map_segments, thus starting the whole process again. Unfortunately this process could not account for the fact that we were not finished with the relaxation process so in some cases - such as the case where code would not fit in a memory region before the R_RISCV_ALIGN relocation was relaxed - sanity checks in generic code would fail. This patch fixes all three of these concerns by reverting back to a system of having only one target relax pass but updating entries in the table of pcrel_hi/pcrel_lo relocs every time any bytes are deleted. Thus we can keep track of the pairs accurately, and we can use the 'again' parameter to restart the entire target relax pass, behaving in the way that generic code expects. Unfortunately we must still have an additional pass to delay deleting AUIPC bytes to avoid ambiguity between pcrel_hi relocs stored in the table after deletion. This pass can only be run once so we may potentially miss out on relaxation opportunities but this is likely to be rare. https://sourceware.org/bugzilla/show_bug.cgi?id=28410 bfd/ * elfnn-riscv.c (riscv_elf_link_hash_table): Removed restart_relax. (riscv_elf_link_hash_table_create): Updated. (riscv_relax_delete_bytes): Moved after the riscv_update_pcgp_relocs. Update the pcgp_relocs table whenever bytes are deleted. (riscv_update_pcgp_relocs): Add function to update the section offset of pcrel_hi and pcrel_lo, and also update the symbol value of pcrel_hi. (_bfd_riscv_relax_call): Need to update the pcgp_relocs table when deleting codes. (_bfd_riscv_relax_lui): Likewise. (_bfd_riscv_relax_tls_le): Likewise. (_bfd_riscv_relax_align): Once we've handled an R_RISCV_ALIGN, we can't relax anything else, so set the sec->sec_flg0 to true. Besides, we don't need to update the pcgp_relocs table at this stage, so just pass NULL pointer as the pcgp_relocs table for riscv_relax_delete_bytes. (_bfd_riscv_relax_section): Use only one pass for all target relaxations. (_bfd_riscv_relax_delete): Likewise, we don't need to update the pcgp_relocs table at this stage, and don't need to set the `again' since restart_relax mechanism is abandoned. (bfd_elfNN_riscv_restart_relax_sections): Removed. (_bfd_riscv_relax_section): Updated. * elfxx-riscv.h (bfd_elf32_riscv_restart_relax_sections): Removed. (bfd_elf64_riscv_restart_relax_sections): Likewise. ld/ * emultempl/riscvelf.em: Revert restart_relax changes and set relax_pass to 3. * testsuite/ld-riscv-elf/align-small-region.d: New testcase. * testsuite/ld-riscv-elf/align-small-region.ld: Likewise. * testsuite/ld-riscv-elf/align-small-region.s: Likewise. * testsuite/ld-riscv-elf/restart-relax.d: Removed sine the restart_relax mechanism is abandoned. * testsuite/ld-riscv-elf/restart-relax.s: Likewise. * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Updated.
106 lines
3.5 KiB
Plaintext
106 lines
3.5 KiB
Plaintext
# This shell script emits a C file. -*- C -*-
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# Copyright (C) 2004-2021 Free Software Foundation, Inc.
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#
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# This file is part of the GNU Binutils.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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# MA 02110-1301, USA.
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fragment <<EOF
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#include "ldmain.h"
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#include "ldctor.h"
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#include "elf/riscv.h"
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#include "elfxx-riscv.h"
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static void
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riscv_elf_before_allocation (void)
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{
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gld${EMULATION_NAME}_before_allocation ();
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if (link_info.discard == discard_sec_merge)
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link_info.discard = discard_l;
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if (!bfd_link_relocatable (&link_info))
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{
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/* We always need at least some relaxation to handle code alignment. */
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if (RELAXATION_DISABLED_BY_USER)
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TARGET_ENABLE_RELAXATION;
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else
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ENABLE_RELAXATION;
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}
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link_info.relax_pass = 3;
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}
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static void
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gld${EMULATION_NAME}_after_allocation (void)
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{
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int need_layout = 0;
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/* Don't attempt to discard unused .eh_frame sections until the final link,
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as we can't reliably tell if they're used until after relaxation. */
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if (!bfd_link_relocatable (&link_info))
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{
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need_layout = bfd_elf_discard_info (link_info.output_bfd, &link_info);
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if (need_layout < 0)
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{
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einfo (_("%X%P: .eh_frame/.stab edit: %E\n"));
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return;
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}
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}
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/* PR 27566, if the phase of data segment is exp_seg_relro_adjust,
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that means we are still adjusting the relro, and shouldn't do the
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relaxations at this stage. Otherwise, we will get the symbol
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values beofore handling the relro, and may cause truncated fails
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when the relax range crossing the data segment. One of the solution
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is to monitor the data segment phase while relaxing, to know whether
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the relro has been handled or not.
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I think we probably need to record more information about data
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segment or alignments in the future, to make sure it is safe
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to doing relaxations. */
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enum phase_enum *phase = &(expld.dataseg.phase);
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bfd_elf${ELFSIZE}_riscv_set_data_segment_info (&link_info, (int *) phase);
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ldelf_map_segments (need_layout);
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}
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/* This is a convenient point to tell BFD about target specific flags.
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After the output has been created, but before inputs are read. */
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static void
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riscv_create_output_section_statements (void)
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{
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/* See PR 22920 for an example of why this is necessary. */
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if (strstr (bfd_get_target (link_info.output_bfd), "riscv") == NULL)
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{
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/* The RISC-V backend needs special fields in the output hash structure.
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These will only be created if the output format is a RISC-V format,
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hence we do not support linking and changing output formats at the
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same time. Use a link followed by objcopy to change output formats. */
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einfo (_("%F%P: error: cannot change output format"
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" whilst linking %s binaries\n"), "RISC-V");
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return;
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}
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}
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EOF
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LDEMUL_BEFORE_ALLOCATION=riscv_elf_before_allocation
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LDEMUL_AFTER_ALLOCATION=gld${EMULATION_NAME}_after_allocation
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LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS=riscv_create_output_section_statements
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