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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com>
*/
#include <stdlib.h>
#include <string.h>
#include "orc.h"
#include "check.h"
#include "warn.h"
int create_orc(struct objtool_file *file)
{
struct instruction *insn;
for_each_insn(file, insn) {
struct orc_entry *orc = &insn->orc;
struct cfi_reg *cfa = &insn->cfi.cfa;
struct cfi_reg *bp = &insn->cfi.regs[CFI_BP];
orc->end = insn->cfi.end;
if (cfa->base == CFI_UNDEFINED) {
orc->sp_reg = ORC_REG_UNDEFINED;
continue;
}
switch (cfa->base) {
case CFI_SP:
orc->sp_reg = ORC_REG_SP;
break;
case CFI_SP_INDIRECT:
orc->sp_reg = ORC_REG_SP_INDIRECT;
break;
case CFI_BP:
orc->sp_reg = ORC_REG_BP;
break;
case CFI_BP_INDIRECT:
orc->sp_reg = ORC_REG_BP_INDIRECT;
break;
case CFI_R10:
orc->sp_reg = ORC_REG_R10;
break;
case CFI_R13:
orc->sp_reg = ORC_REG_R13;
break;
case CFI_DI:
orc->sp_reg = ORC_REG_DI;
break;
case CFI_DX:
orc->sp_reg = ORC_REG_DX;
break;
default:
WARN_FUNC("unknown CFA base reg %d",
insn->sec, insn->offset, cfa->base);
return -1;
}
switch(bp->base) {
case CFI_UNDEFINED:
orc->bp_reg = ORC_REG_UNDEFINED;
break;
case CFI_CFA:
orc->bp_reg = ORC_REG_PREV_SP;
break;
case CFI_BP:
orc->bp_reg = ORC_REG_BP;
break;
default:
WARN_FUNC("unknown BP base reg %d",
insn->sec, insn->offset, bp->base);
return -1;
}
orc->sp_offset = cfa->offset;
orc->bp_offset = bp->offset;
orc->type = insn->cfi.type;
}
return 0;
}
static int create_orc_entry(struct elf *elf, struct section *u_sec, struct section *ip_relasec,
unsigned int idx, struct section *insn_sec,
unsigned long insn_off, struct orc_entry *o)
{
struct orc_entry *orc;
struct rela *rela;
/* populate ORC data */
orc = (struct orc_entry *)u_sec->data->d_buf + idx;
memcpy(orc, o, sizeof(*orc));
/* populate rela for ip */
rela = malloc(sizeof(*rela));
if (!rela) {
perror("malloc");
return -1;
}
memset(rela, 0, sizeof(*rela));
if (insn_sec->sym) {
rela->sym = insn_sec->sym;
rela->addend = insn_off;
} else {
/*
* The Clang assembler doesn't produce section symbols, so we
* have to reference the function symbol instead:
*/
rela->sym = find_symbol_containing(insn_sec, insn_off);
if (!rela->sym) {
/*
* Hack alert. This happens when we need to reference
* the NOP pad insn immediately after the function.
*/
rela->sym = find_symbol_containing(insn_sec,
insn_off - 1);
}
if (!rela->sym) {
WARN("missing symbol for insn at offset 0x%lx\n",
insn_off);
return -1;
}
rela->addend = insn_off - rela->sym->offset;
}
rela->type = R_X86_64_PC32;
rela->offset = idx * sizeof(int);
rela->sec = ip_relasec;
list_add_tail(&rela->list, &ip_relasec->rela_list);
hash_add(elf->rela_hash, &rela->hash, rela_hash(rela));
return 0;
}
int create_orc_sections(struct objtool_file *file)
{
struct instruction *insn, *prev_insn;
struct section *sec, *u_sec, *ip_relasec;
unsigned int idx;
struct orc_entry empty = {
.sp_reg = ORC_REG_UNDEFINED,
.bp_reg = ORC_REG_UNDEFINED,
.type = ORC_TYPE_CALL,
};
sec = find_section_by_name(file->elf, ".orc_unwind");
if (sec) {
WARN("file already has .orc_unwind section, skipping");
return -1;
}
/* count the number of needed orcs */
idx = 0;
for_each_sec(file, sec) {
if (!sec->text)
continue;
prev_insn = NULL;
sec_for_each_insn(file, sec, insn) {
if (!prev_insn ||
memcmp(&insn->orc, &prev_insn->orc,
sizeof(struct orc_entry))) {
idx++;
}
prev_insn = insn;
}
/* section terminator */
if (prev_insn)
idx++;
}
if (!idx)
return -1;
/* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
if (!sec)
return -1;
ip_relasec = elf_create_rela_section(file->elf, sec);
if (!ip_relasec)
return -1;
/* create .orc_unwind section */
u_sec = elf_create_section(file->elf, ".orc_unwind",
sizeof(struct orc_entry), idx);
/* populate sections */
idx = 0;
for_each_sec(file, sec) {
if (!sec->text)
continue;
prev_insn = NULL;
sec_for_each_insn(file, sec, insn) {
if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
sizeof(struct orc_entry))) {
if (create_orc_entry(file->elf, u_sec, ip_relasec, idx,
insn->sec, insn->offset,
&insn->orc))
return -1;
idx++;
}
prev_insn = insn;
}
/* section terminator */
if (prev_insn) {
if (create_orc_entry(file->elf, u_sec, ip_relasec, idx,
prev_insn->sec,
prev_insn->offset + prev_insn->len,
&empty))
return -1;
idx++;
}
}
if (elf_rebuild_rela_section(ip_relasec))
return -1;
return 0;
}
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