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Currently objtool only collects information about relocations with addends. In recordmcount, which we are about to merge into objtool, some supported architectures do not use rela relocations. Signed-off-by: Matt Helsley <mhelsley@vmware.com> Reviewed-by: Julien Thierry <jthierry@redhat.com> Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
230 lines
4.7 KiB
C
230 lines
4.7 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 "check.h"
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#include "warn.h"
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int create_orc(struct objtool_file *file)
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{
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struct instruction *insn;
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for_each_insn(file, insn) {
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struct orc_entry *orc = &insn->orc;
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struct cfi_reg *cfa = &insn->cfi.cfa;
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struct cfi_reg *bp = &insn->cfi.regs[CFI_BP];
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orc->end = insn->cfi.end;
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if (cfa->base == CFI_UNDEFINED) {
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orc->sp_reg = ORC_REG_UNDEFINED;
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continue;
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}
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switch (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, 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 = cfa->offset;
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orc->bp_offset = bp->offset;
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orc->type = insn->cfi.type;
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}
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return 0;
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}
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static int create_orc_entry(struct elf *elf, struct section *u_sec, struct section *ip_relocsec,
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unsigned int idx, struct section *insn_sec,
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unsigned long insn_off, struct orc_entry *o)
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{
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struct orc_entry *orc;
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struct reloc *reloc;
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/* populate ORC data */
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orc = (struct orc_entry *)u_sec->data->d_buf + idx;
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memcpy(orc, o, sizeof(*orc));
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/* populate reloc for ip */
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reloc = malloc(sizeof(*reloc));
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if (!reloc) {
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perror("malloc");
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return -1;
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}
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memset(reloc, 0, sizeof(*reloc));
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if (insn_sec->sym) {
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reloc->sym = insn_sec->sym;
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reloc->addend = insn_off;
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} else {
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/*
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* The Clang assembler doesn't produce section symbols, so we
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* have to reference the function symbol instead:
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*/
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reloc->sym = find_symbol_containing(insn_sec, insn_off);
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if (!reloc->sym) {
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/*
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* Hack alert. This happens when we need to reference
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* the NOP pad insn immediately after the function.
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*/
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reloc->sym = find_symbol_containing(insn_sec,
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insn_off - 1);
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}
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if (!reloc->sym) {
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WARN("missing symbol for insn at offset 0x%lx\n",
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insn_off);
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return -1;
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}
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reloc->addend = insn_off - reloc->sym->offset;
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}
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reloc->type = R_X86_64_PC32;
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reloc->offset = idx * sizeof(int);
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reloc->sec = ip_relocsec;
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elf_add_reloc(elf, reloc);
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return 0;
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}
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int create_orc_sections(struct objtool_file *file)
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{
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struct instruction *insn, *prev_insn;
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struct section *sec, *u_sec, *ip_relocsec;
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unsigned int idx;
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struct orc_entry empty = {
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.sp_reg = ORC_REG_UNDEFINED,
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.bp_reg = ORC_REG_UNDEFINED,
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.type = ORC_TYPE_CALL,
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};
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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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/* count the number of needed orcs */
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idx = 0;
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for_each_sec(file, sec) {
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if (!sec->text)
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continue;
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prev_insn = NULL;
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sec_for_each_insn(file, sec, insn) {
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if (!prev_insn ||
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memcmp(&insn->orc, &prev_insn->orc,
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sizeof(struct orc_entry))) {
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idx++;
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}
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prev_insn = insn;
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}
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/* section terminator */
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if (prev_insn)
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idx++;
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}
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if (!idx)
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return -1;
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/* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
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sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
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if (!sec)
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return -1;
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ip_relocsec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
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if (!ip_relocsec)
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return -1;
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/* create .orc_unwind section */
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u_sec = elf_create_section(file->elf, ".orc_unwind",
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sizeof(struct orc_entry), idx);
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/* populate sections */
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idx = 0;
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for_each_sec(file, sec) {
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if (!sec->text)
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continue;
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prev_insn = NULL;
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sec_for_each_insn(file, sec, insn) {
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if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
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sizeof(struct orc_entry))) {
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if (create_orc_entry(file->elf, u_sec, ip_relocsec, idx,
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insn->sec, insn->offset,
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&insn->orc))
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return -1;
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idx++;
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}
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prev_insn = insn;
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}
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/* section terminator */
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if (prev_insn) {
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if (create_orc_entry(file->elf, u_sec, ip_relocsec, idx,
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prev_insn->sec,
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prev_insn->offset + prev_insn->len,
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&empty))
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return -1;
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idx++;
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}
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}
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if (elf_rebuild_reloc_section(ip_relocsec))
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return -1;
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return 0;
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}
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