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![Josh Poimboeuf](/assets/img/avatar_default.png)
It's easier to use and also gives easy access to the instruction's containing function, which is useful for printing that function's symbol. It will also be useful in the future for rate-limiting and disassembly of warned functions. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/2eaa3155c90fba683d8723599f279c46025b75f3.1681325924.git.jpoimboe@kernel.org
258 lines
5.7 KiB
C
258 lines
5.7 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 <linux/objtool_types.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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/*
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* This is usually either unreachable nops/traps (which don't
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* trigger unreachable instruction warnings), or
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* STACK_FRAME_NON_STANDARD functions.
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*/
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orc->type = ORC_TYPE_UNDEFINED;
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return 0;
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}
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switch (cfi->type) {
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case UNWIND_HINT_TYPE_UNDEFINED:
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orc->type = ORC_TYPE_UNDEFINED;
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return 0;
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case UNWIND_HINT_TYPE_END_OF_STACK:
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orc->type = ORC_TYPE_END_OF_STACK;
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return 0;
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case UNWIND_HINT_TYPE_CALL:
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orc->type = ORC_TYPE_CALL;
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break;
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case UNWIND_HINT_TYPE_REGS:
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orc->type = ORC_TYPE_REGS;
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break;
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case UNWIND_HINT_TYPE_REGS_PARTIAL:
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orc->type = ORC_TYPE_REGS_PARTIAL;
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break;
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default:
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WARN_INSN(insn, "unknown unwind hint type %d", cfi->type);
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return -1;
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}
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orc->signal = cfi->signal;
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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_INSN(insn, "unknown CFA base reg %d", 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_INSN(insn, "unknown BP base reg %d", 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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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(elf, orc->sp_offset);
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orc->bp_offset = bswap_if_needed(elf, 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 = { .type = ORC_TYPE_UNDEFINED };
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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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