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- // plugin_section_alignment.cc -- plugins to test ordering with {size,alignment}
- //
- // Copyright (C) 2016-2022 Free Software Foundation, Inc.
- // Written by Than McIntosh <thanm@google.com>.
- //
- // This file is part of gold.
- //
- // This program is free software; you can redistribute it and/or modify
- // it under the terms of the GNU General Public License as published by
- // the Free Software Foundation; either version 3 of the License, or
- // (at your option) any later version.
- //
- // This program is distributed in the hope that it will be useful,
- // but WITHOUT ANY WARRANTY; without even the implied warranty of
- // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- // GNU General Public License for more details.
- //
- // You should have received a copy of the GNU General Public License
- // along with this program; if not, write to the Free Software
- // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
- // MA 02110-1301, USA.
- //
- #ifdef HAVE_CONFIG_H
- #include "config.h"
- #endif
- #include <assert.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <string>
- #include <vector>
- #include <algorithm>
- #include "plugin-api.h"
- static ld_plugin_get_input_section_count get_input_section_count = NULL;
- static ld_plugin_get_input_section_alignment get_input_section_alignment = NULL;
- static ld_plugin_get_input_section_size get_input_section_size = NULL;
- static ld_plugin_get_input_section_name get_input_section_name = NULL;
- static ld_plugin_update_section_order update_section_order = NULL;
- static ld_plugin_allow_section_ordering allow_section_ordering = NULL;
- extern "C" {
- enum ld_plugin_status onload(struct ld_plugin_tv *tv);
- enum ld_plugin_status claim_file_hook(const struct ld_plugin_input_file *file,
- int *claimed);
- enum ld_plugin_status all_symbols_read_hook(void);
- }
- typedef enum { FL_BSS, FL_DATA, FL_RODATA, FL_UNKNOWN } sec_flavor;
- inline static int is_prefix_of(const char *prefix, const char *str)
- {
- return strncmp(prefix, str, strlen(prefix)) == 0;
- }
- inline static sec_flavor flavor_from_name(const char *secname)
- {
- if (is_prefix_of(".data.v", secname)) {
- return FL_DATA;
- } else if (is_prefix_of(".bss.v", secname)) {
- return FL_BSS;
- } else if (is_prefix_of(".rodata.v", secname)) {
- return FL_RODATA;
- } else {
- return FL_UNKNOWN;
- }
- }
- struct SectionInfo {
- ld_plugin_section plugin_section;
- std::string name;
- uint64_t size;
- sec_flavor flavor;
- unsigned align;
- static bool SectionInfoLt(const SectionInfo &i1,
- const SectionInfo &i2)
- {
- if (i1.flavor != i2.flavor) {
- return ((unsigned) i1.flavor) < ((unsigned) i2.flavor);
- }
- switch (i1.flavor) {
- case FL_DATA:
- // Sort data items by increasing alignment then increasing size
- if (i1.align != i2.align) {
- return ((unsigned) i1.align) < ((unsigned) i2.align);
- }
- if (i1.size != i2.size) {
- return ((unsigned) i1.size) < ((unsigned) i2.size);
- }
- break;
- case FL_BSS:
- // Sort bss items by decreasing alignment then decreasing size
- if (i1.align != i2.align) {
- return ((unsigned) i2.align) < ((unsigned) i1.align);
- }
- if (i1.size != i2.size) {
- return ((unsigned) i2.size) < ((unsigned) i1.size);
- }
- break;
- case FL_RODATA:
- // Sort rodata items by decreasing alignment then increasing size
- if (i1.align != i2.align) {
- return ((unsigned) i2.align) < ((unsigned) i1.align);
- }
- if (i1.size != i2.size) {
- return ((unsigned) i1.size) < ((unsigned) i2.size);
- }
- default:
- break;
- }
- // Break ties by name
- return i1.name.compare(i2.name) < 0;
- }
- };
- typedef std::vector<SectionInfo> section_info_vector;
- section_info_vector raw_sections;
- // Set to 1 for debugging output
- unsigned trace = 0;
- extern "C" {
- // Plugin entry point.
- enum ld_plugin_status onload(struct ld_plugin_tv *tv)
- {
- struct ld_plugin_tv *entry;
- for (entry = tv; entry->tv_tag != LDPT_NULL; ++entry)
- {
- switch (entry->tv_tag)
- {
- case LDPT_OPTION:
- if (!strcmp(entry->tv_u.tv_string,"-trace")) {
- fprintf(stderr, "enabling tracing\n");
- trace += 1;
- } else {
- fprintf(stderr, "unknown plugin option %s", entry->tv_u.tv_string);
- }
- break;
- case LDPT_REGISTER_CLAIM_FILE_HOOK:
- assert((*entry->tv_u.tv_register_claim_file)(claim_file_hook) ==
- LDPS_OK);
- break;
- case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK:
- assert((*entry->tv_u.tv_register_all_symbols_read)(
- all_symbols_read_hook) == LDPS_OK);
- break;
- case LDPT_GET_INPUT_SECTION_COUNT:
- get_input_section_count = *entry->tv_u.tv_get_input_section_count;
- break;
- case LDPT_GET_INPUT_SECTION_NAME:
- get_input_section_name = *entry->tv_u.tv_get_input_section_name;
- break;
- case LDPT_GET_INPUT_SECTION_ALIGNMENT:
- get_input_section_alignment =
- *entry->tv_u.tv_get_input_section_alignment;
- break;
- case LDPT_GET_INPUT_SECTION_SIZE:
- get_input_section_size = *entry->tv_u.tv_get_input_section_size;
- break;
- case LDPT_UPDATE_SECTION_ORDER:
- update_section_order = *entry->tv_u.tv_update_section_order;
- break;
- case LDPT_ALLOW_SECTION_ORDERING:
- allow_section_ordering = *entry->tv_u.tv_allow_section_ordering;
- break;
- default:
- break;
- }
- }
- if (get_input_section_count == NULL || get_input_section_alignment == NULL ||
- get_input_section_size == NULL || get_input_section_name == NULL ||
- update_section_order == NULL || allow_section_ordering == NULL) {
- fprintf(stderr, "Some interfaces are missing\n");
- return LDPS_ERR;
- }
- return LDPS_OK;
- }
- // This function is called by the linker for every new object it encounters.
- enum ld_plugin_status claim_file_hook(const struct ld_plugin_input_file *file,
- int *claimed)
- {
- static bool is_ordering_specified = false;
- struct ld_plugin_section section;
- unsigned count = 0;
- unsigned shndx;
- *claimed = 0;
- if (!is_ordering_specified) {
- // Inform the linker to prepare for section reordering.
- (*allow_section_ordering)();
- is_ordering_specified = true;
- }
- (*get_input_section_count)(file->handle, &count);
- for (shndx = 0; shndx < count; ++shndx) {
- char *name = NULL;
- section.handle = file->handle;
- section.shndx = shndx;
- (*get_input_section_name)(section, &name);
- if (is_prefix_of(".data.v", name) ||
- is_prefix_of(".bss.v", name) ||
- is_prefix_of(".rodata.v", name)) {
- SectionInfo si;
- si.plugin_section.handle = file->handle;
- si.plugin_section.shndx = shndx;
- (*get_input_section_size)(section, &si.size);
- (*get_input_section_alignment)(section, &si.align);
- si.name = name;
- si.flavor = flavor_from_name(name);
- raw_sections.push_back(si);
- }
- }
- return LDPS_OK;
- }
- // This function is called by the linker after all the symbols have been read.
- // At this stage, it is fine to tell the linker the desired function order.
- enum ld_plugin_status all_symbols_read_hook(void)
- {
- // We expect to see a total of twelve sections -- if this is not the case
- // then something went wrong somewhere along the way.
- if (raw_sections.size() != 12) {
- fprintf(stderr, "Expected 12 sections, found %u sections",
- (unsigned) raw_sections.size());
- return LDPS_ERR;
- }
- std::sort(raw_sections.begin(), raw_sections.end(),
- SectionInfo::SectionInfoLt);
- struct ld_plugin_section section_list[12];
- for (unsigned ii = 0; ii < 12; ++ii) {
- section_list[ii] = raw_sections[ii].plugin_section;
- }
- if (trace) {
- fprintf(stderr, "Specified section order is:\n");
- for (section_info_vector::iterator it = raw_sections.begin();
- it != raw_sections.end();
- ++it) {
- const SectionInfo &si = (*it);
- fprintf(stderr, "Idx=%u Name=%s Align=%u Size=%u\n",
- si.plugin_section.shndx, si.name.c_str(), si.align,
- (unsigned) si.size);
- }
- }
- update_section_order(section_list, 12);
- return LDPS_OK;
- }
- } // end extern "C"
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