189 lines
5.9 KiB
C
189 lines
5.9 KiB
C
/* plugin_section_reorder.c -- Simple plugin to reorder function sections
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Copyright (C) 2011-2017 Free Software Foundation, Inc.
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Written by Sriraman Tallam <tmsriram@google.com>.
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This file is part of gold.
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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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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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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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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "plugin-api.h"
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static ld_plugin_get_input_section_count get_input_section_count = NULL;
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static ld_plugin_get_input_section_type get_input_section_type = NULL;
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static ld_plugin_get_input_section_name get_input_section_name = NULL;
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static ld_plugin_get_input_section_contents get_input_section_contents = NULL;
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static ld_plugin_update_section_order update_section_order = NULL;
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static ld_plugin_allow_section_ordering allow_section_ordering = NULL;
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static ld_plugin_allow_unique_segment_for_sections
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allow_unique_segment_for_sections = NULL;
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static ld_plugin_unique_segment_for_sections unique_segment_for_sections = NULL;
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enum ld_plugin_status onload(struct ld_plugin_tv *tv);
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enum ld_plugin_status claim_file_hook(const struct ld_plugin_input_file *file,
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int *claimed);
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enum ld_plugin_status all_symbols_read_hook(void);
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/* Plugin entry point. */
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enum ld_plugin_status
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onload(struct ld_plugin_tv *tv)
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{
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struct ld_plugin_tv *entry;
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for (entry = tv; entry->tv_tag != LDPT_NULL; ++entry)
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{
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switch (entry->tv_tag)
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{
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case LDPT_REGISTER_CLAIM_FILE_HOOK:
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assert((*entry->tv_u.tv_register_claim_file) (claim_file_hook)
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== LDPS_OK);
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break;
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case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
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assert((*entry->tv_u.tv_register_all_symbols_read)
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(all_symbols_read_hook)
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== LDPS_OK);
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break;
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case LDPT_GET_INPUT_SECTION_COUNT:
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get_input_section_count = *entry->tv_u.tv_get_input_section_count;
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break;
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case LDPT_GET_INPUT_SECTION_TYPE:
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get_input_section_type = *entry->tv_u.tv_get_input_section_type;
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break;
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case LDPT_GET_INPUT_SECTION_NAME:
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get_input_section_name = *entry->tv_u.tv_get_input_section_name;
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break;
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case LDPT_GET_INPUT_SECTION_CONTENTS:
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get_input_section_contents
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= *entry->tv_u.tv_get_input_section_contents;
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break;
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case LDPT_UPDATE_SECTION_ORDER:
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update_section_order = *entry->tv_u.tv_update_section_order;
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break;
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case LDPT_ALLOW_SECTION_ORDERING:
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allow_section_ordering = *entry->tv_u.tv_allow_section_ordering;
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break;
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case LDPT_ALLOW_UNIQUE_SEGMENT_FOR_SECTIONS:
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allow_unique_segment_for_sections
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= *entry->tv_u.tv_allow_unique_segment_for_sections;
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case LDPT_UNIQUE_SEGMENT_FOR_SECTIONS:
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unique_segment_for_sections
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= *entry->tv_u.tv_unique_segment_for_sections;
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break;
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default:
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break;
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}
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}
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if (get_input_section_count == NULL
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|| get_input_section_type == NULL
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|| get_input_section_name == NULL
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|| get_input_section_contents == NULL
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|| update_section_order == NULL
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|| allow_section_ordering == NULL
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|| allow_unique_segment_for_sections == NULL
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|| unique_segment_for_sections == NULL)
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{
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fprintf(stderr, "Some interfaces are missing\n");
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return LDPS_ERR;
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}
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return LDPS_OK;
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}
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inline static int is_prefix_of(const char *prefix, const char *str)
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{
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return strncmp(prefix, str, strlen (prefix)) == 0;
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}
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struct ld_plugin_section section_list[3];
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int num_entries = 0;
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/* This function is called by the linker for every new object it encounters. */
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enum ld_plugin_status
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claim_file_hook(const struct ld_plugin_input_file *file, int *claimed)
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{
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static int is_ordering_specified = 0;
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struct ld_plugin_section section;
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unsigned int count = 0;
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unsigned int shndx;
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*claimed = 0;
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if (is_ordering_specified == 0)
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{
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/* Inform the linker to prepare for section reordering. */
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(*allow_section_ordering)();
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/* Inform the linker to prepare to map some sections to unique
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segments. */
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(*allow_unique_segment_for_sections)();
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is_ordering_specified = 1;
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}
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(*get_input_section_count)(file->handle, &count);
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for (shndx = 0; shndx < count; ++shndx)
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{
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char *name = NULL;
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int position = 3;
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section.handle = file->handle;
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section.shndx = shndx;
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(*get_input_section_name)(section, &name);
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/* Order is foo() followed by bar() followed by baz() */
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if (is_prefix_of(".text.", name))
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{
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if (strstr(name, "_Z3foov") != NULL)
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position = 0;
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else if (strstr(name, "_Z3barv") != NULL)
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position = 1;
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else if (strstr(name, "_Z3bazv") != NULL)
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position = 2;
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else
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position = 3;
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}
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if (position < 3)
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{
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section_list[position].handle = file->handle;
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section_list[position].shndx = shndx;
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num_entries++;
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}
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}
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return LDPS_OK;
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}
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/* This function is called by the linker after all the symbols have been read.
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At this stage, it is fine to tell the linker the desired function order. */
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enum ld_plugin_status
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all_symbols_read_hook(void)
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{
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if (num_entries == 3)
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{
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update_section_order(section_list, num_entries);
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unique_segment_for_sections (".text.plugin_created_unique", 0, 0x1000,
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section_list, num_entries);
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}
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return LDPS_OK;
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}
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