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245 lines
5.3 KiB
C
245 lines
5.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <linux/objtool.h>
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#include <asm/orc_types.h>
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#include <objtool/check.h>
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#include <objtool/warn.h>
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#include <objtool/endianness.h>
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static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi,
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struct instruction *insn)
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{
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struct cfi_reg *bp = &cfi->regs[CFI_BP];
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memset(orc, 0, sizeof(*orc));
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if (!cfi) {
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orc->end = 0;
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orc->sp_reg = ORC_REG_UNDEFINED;
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return 0;
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}
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orc->end = cfi->end;
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if (cfi->cfa.base == CFI_UNDEFINED) {
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orc->sp_reg = ORC_REG_UNDEFINED;
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return 0;
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}
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switch (cfi->cfa.base) {
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case CFI_SP:
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orc->sp_reg = ORC_REG_SP;
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break;
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case CFI_SP_INDIRECT:
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orc->sp_reg = ORC_REG_SP_INDIRECT;
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break;
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case CFI_BP:
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orc->sp_reg = ORC_REG_BP;
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break;
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case CFI_BP_INDIRECT:
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orc->sp_reg = ORC_REG_BP_INDIRECT;
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break;
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case CFI_R10:
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orc->sp_reg = ORC_REG_R10;
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break;
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case CFI_R13:
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orc->sp_reg = ORC_REG_R13;
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break;
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case CFI_DI:
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orc->sp_reg = ORC_REG_DI;
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break;
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case CFI_DX:
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orc->sp_reg = ORC_REG_DX;
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break;
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default:
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WARN_FUNC("unknown CFA base reg %d",
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insn->sec, insn->offset, cfi->cfa.base);
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return -1;
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}
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switch (bp->base) {
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case CFI_UNDEFINED:
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orc->bp_reg = ORC_REG_UNDEFINED;
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break;
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case CFI_CFA:
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orc->bp_reg = ORC_REG_PREV_SP;
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break;
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case CFI_BP:
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orc->bp_reg = ORC_REG_BP;
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break;
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default:
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WARN_FUNC("unknown BP base reg %d",
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insn->sec, insn->offset, bp->base);
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return -1;
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}
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orc->sp_offset = cfi->cfa.offset;
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orc->bp_offset = bp->offset;
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orc->type = cfi->type;
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return 0;
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}
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static int write_orc_entry(struct elf *elf, struct section *orc_sec,
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struct section *ip_sec, unsigned int idx,
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struct section *insn_sec, unsigned long insn_off,
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struct orc_entry *o)
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{
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struct orc_entry *orc;
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/* populate ORC data */
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orc = (struct orc_entry *)orc_sec->data->d_buf + idx;
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memcpy(orc, o, sizeof(*orc));
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orc->sp_offset = bswap_if_needed(orc->sp_offset);
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orc->bp_offset = bswap_if_needed(orc->bp_offset);
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/* populate reloc for ip */
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if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32,
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insn_sec, insn_off))
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return -1;
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return 0;
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}
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struct orc_list_entry {
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struct list_head list;
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struct orc_entry orc;
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struct section *insn_sec;
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unsigned long insn_off;
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};
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static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc,
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struct section *sec, unsigned long offset)
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{
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struct orc_list_entry *entry = malloc(sizeof(*entry));
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if (!entry) {
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WARN("malloc failed");
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return -1;
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}
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entry->orc = *orc;
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entry->insn_sec = sec;
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entry->insn_off = offset;
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list_add_tail(&entry->list, orc_list);
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return 0;
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}
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static unsigned long alt_group_len(struct alt_group *alt_group)
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{
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return alt_group->last_insn->offset +
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alt_group->last_insn->len -
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alt_group->first_insn->offset;
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}
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int orc_create(struct objtool_file *file)
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{
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struct section *sec, *orc_sec;
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unsigned int nr = 0, idx = 0;
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struct orc_list_entry *entry;
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struct list_head orc_list;
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struct orc_entry null = {
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.sp_reg = ORC_REG_UNDEFINED,
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.bp_reg = ORC_REG_UNDEFINED,
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.type = UNWIND_HINT_TYPE_CALL,
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};
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/* Build a deduplicated list of ORC entries: */
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INIT_LIST_HEAD(&orc_list);
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for_each_sec(file, sec) {
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struct orc_entry orc, prev_orc = {0};
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struct instruction *insn;
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bool empty = true;
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if (!sec->text)
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continue;
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sec_for_each_insn(file, sec, insn) {
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struct alt_group *alt_group = insn->alt_group;
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int i;
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if (!alt_group) {
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if (init_orc_entry(&orc, insn->cfi, insn))
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return -1;
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if (!memcmp(&prev_orc, &orc, sizeof(orc)))
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continue;
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if (orc_list_add(&orc_list, &orc, sec,
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insn->offset))
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return -1;
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nr++;
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prev_orc = orc;
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empty = false;
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continue;
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}
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/*
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* Alternatives can have different stack layout
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* possibilities (but they shouldn't conflict).
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* Instead of traversing the instructions, use the
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* alt_group's flattened byte-offset-addressed CFI
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* array.
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*/
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for (i = 0; i < alt_group_len(alt_group); i++) {
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struct cfi_state *cfi = alt_group->cfi[i];
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if (!cfi)
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continue;
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/* errors are reported on the original insn */
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if (init_orc_entry(&orc, cfi, insn))
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return -1;
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if (!memcmp(&prev_orc, &orc, sizeof(orc)))
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continue;
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if (orc_list_add(&orc_list, &orc, insn->sec,
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insn->offset + i))
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return -1;
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nr++;
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prev_orc = orc;
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empty = false;
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}
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/* Skip to the end of the alt_group */
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insn = alt_group->last_insn;
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}
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/* Add a section terminator */
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if (!empty) {
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orc_list_add(&orc_list, &null, sec, sec->sh.sh_size);
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nr++;
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}
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}
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if (!nr)
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return 0;
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/* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */
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sec = find_section_by_name(file->elf, ".orc_unwind");
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if (sec) {
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WARN("file already has .orc_unwind section, skipping");
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return -1;
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}
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orc_sec = elf_create_section(file->elf, ".orc_unwind", 0,
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sizeof(struct orc_entry), nr);
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if (!orc_sec)
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return -1;
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sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr);
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if (!sec)
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return -1;
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/* Write ORC entries to sections: */
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list_for_each_entry(entry, &orc_list, list) {
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if (write_orc_entry(file->elf, orc_sec, sec, idx++,
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entry->insn_sec, entry->insn_off,
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&entry->orc))
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return -1;
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}
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return 0;
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}
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