tools/objtool/orc_gen.c

   1 /*
   2  * Copyright (C) 2017 Josh Poimboeuf <[email protected]>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <stdlib.h>
  19 #include <string.h>
  20
  21 #include "orc.h"
  22 #include "check.h"
  23 #include "warn.h"
  24
  25 int create_orc(struct objtool_file *file)
  26 {
  27         struct instruction *insn;
  28
  29         for_each_insn(file, insn) {
  30                 struct orc_entry *orc = &insn->orc;
  31                 struct cfi_reg *cfa = &insn->state.cfa;
  32                 struct cfi_reg *bp = &insn->state.regs[CFI_BP];
  33
  34                 orc->end = insn->state.end;
  35
  36                 if (cfa->base == CFI_UNDEFINED) {
  37                         orc->sp_reg = ORC_REG_UNDEFINED;
  38                         continue;
  39                 }
  40
  41                 switch (cfa->base) {
  42                 case CFI_SP:
  43                         orc->sp_reg = ORC_REG_SP;
  44                         break;
  45                 case CFI_SP_INDIRECT:
  46                         orc->sp_reg = ORC_REG_SP_INDIRECT;
  47                         break;
  48                 case CFI_BP:
  49                         orc->sp_reg = ORC_REG_BP;
  50                         break;
  51                 case CFI_BP_INDIRECT:
  52                         orc->sp_reg = ORC_REG_BP_INDIRECT;
  53                         break;
  54                 case CFI_R10:
  55                         orc->sp_reg = ORC_REG_R10;
  56                         break;
  57                 case CFI_R13:
  58                         orc->sp_reg = ORC_REG_R13;
  59                         break;
  60                 case CFI_DI:
  61                         orc->sp_reg = ORC_REG_DI;
  62                         break;
  63                 case CFI_DX:
  64                         orc->sp_reg = ORC_REG_DX;
  65                         break;
  66                 default:
  67                         WARN_FUNC("unknown CFA base reg %d",
  68                                   insn->sec, insn->offset, cfa->base);
  69                         return -1;
  70                 }
  71
  72                 switch(bp->base) {
  73                 case CFI_UNDEFINED:
  74                         orc->bp_reg = ORC_REG_UNDEFINED;
  75                         break;
  76                 case CFI_CFA:
  77                         orc->bp_reg = ORC_REG_PREV_SP;
  78                         break;
  79                 case CFI_BP:
  80                         orc->bp_reg = ORC_REG_BP;
  81                         break;
  82                 default:
  83                         WARN_FUNC("unknown BP base reg %d",
  84                                   insn->sec, insn->offset, bp->base);
  85                         return -1;
  86                 }
  87
  88                 orc->sp_offset = cfa->offset;
  89                 orc->bp_offset = bp->offset;
  90                 orc->type = insn->state.type;
  91         }
  92
  93         return 0;
  94 }
  95
  96 static int create_orc_entry(struct section *u_sec, struct section *ip_relasec,
  97                                 unsigned int idx, struct section *insn_sec,
  98                                 unsigned long insn_off, struct orc_entry *o)
  99 {
 100         struct orc_entry *orc;
 101         struct rela *rela;
 102
 103         if (!insn_sec->sym) {
 104                 WARN("missing symbol for section %s", insn_sec->name);
 105                 return -1;
 106         }
 107
 108         /* populate ORC data */
 109         orc = (struct orc_entry *)u_sec->data->d_buf + idx;
 110         memcpy(orc, o, sizeof(*orc));
 111
 112         /* populate rela for ip */
 113         rela = malloc(sizeof(*rela));
 114         if (!rela) {
 115                 perror("malloc");
 116                 return -1;
 117         }
 118         memset(rela, 0, sizeof(*rela));
 119
 120         rela->sym = insn_sec->sym;
 121         rela->addend = insn_off;
 122         rela->type = R_X86_64_PC32;
 123         rela->offset = idx * sizeof(int);
 124
 125         list_add_tail(&rela->list, &ip_relasec->rela_list);
 126         hash_add(ip_relasec->rela_hash, &rela->hash, rela->offset);
 127
 128         return 0;
 129 }
 130
 131 int create_orc_sections(struct objtool_file *file)
 132 {
 133         struct instruction *insn, *prev_insn;
 134         struct section *sec, *u_sec, *ip_relasec;
 135         unsigned int idx;
 136
 137         struct orc_entry empty = {
 138                 .sp_reg = ORC_REG_UNDEFINED,
 139                 .bp_reg  = ORC_REG_UNDEFINED,
 140                 .type    = ORC_TYPE_CALL,
 141         };
 142
 143         sec = find_section_by_name(file->elf, ".orc_unwind");
 144         if (sec) {
 145                 WARN("file already has .orc_unwind section, skipping");
 146                 return -1;
 147         }
 148
 149         /* count the number of needed orcs */
 150         idx = 0;
 151         for_each_sec(file, sec) {
 152                 if (!sec->text)
 153                         continue;
 154
 155                 prev_insn = NULL;
 156                 sec_for_each_insn(file, sec, insn) {
 157                         if (!prev_insn ||
 158                             memcmp(&insn->orc, &prev_insn->orc,
 159                                    sizeof(struct orc_entry))) {
 160                                 idx++;
 161                         }
 162                         prev_insn = insn;
 163                 }
 164
 165                 /* section terminator */
 166                 if (prev_insn)
 167                         idx++;
 168         }
 169         if (!idx)
 170                 return -1;
 171
 172
 173         /* create .orc_unwind_ip and .rela.orc_unwind_ip sections */
 174         sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx);
 175         if (!sec)
 176                 return -1;
 177
 178         ip_relasec = elf_create_rela_section(file->elf, sec);
 179         if (!ip_relasec)
 180                 return -1;
 181
 182         /* create .orc_unwind section */
 183         u_sec = elf_create_section(file->elf, ".orc_unwind",
 184                                    sizeof(struct orc_entry), idx);
 185
 186         /* populate sections */
 187         idx = 0;
 188         for_each_sec(file, sec) {
 189                 if (!sec->text)
 190                         continue;
 191
 192                 prev_insn = NULL;
 193                 sec_for_each_insn(file, sec, insn) {
 194                         if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc,
 195                                                  sizeof(struct orc_entry))) {
 196
 197                                 if (create_orc_entry(u_sec, ip_relasec, idx,
 198                                                      insn->sec, insn->offset,
 199                                                      &insn->orc))
 200                                         return -1;
 201
 202                                 idx++;
 203                         }
 204                         prev_insn = insn;
 205                 }
 206
 207                 /* section terminator */
 208                 if (prev_insn) {
 209                         if (create_orc_entry(u_sec, ip_relasec, idx,
 210                                              prev_insn->sec,
 211                                              prev_insn->offset + prev_insn->len,
 212                                              &empty))
 213                                 return -1;
 214
 215                         idx++;
 216                 }
 217         }
 218
 219         if (elf_rebuild_rela_section(ip_relasec))
 220                 return -1;
 221
 222         return 0;
 223 }