diff options
Diffstat (limited to 'src/cxx.c')
| -rw-r--r-- | src/cxx.c | 643 |
1 files changed, 643 insertions, 0 deletions
diff --git a/src/cxx.c b/src/cxx.c new file mode 100644 index 0000000..4391ebe --- /dev/null +++ b/src/cxx.c @@ -0,0 +1,643 @@ +/* Copyright (C) 2001, 2002, 2003, 2007, 2009 Red Hat, Inc. + Written by Jakub Jelinek <jakub@redhat.com>, 2001. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2, or (at your option) + any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#include <config.h> +#include <alloca.h> +#include <assert.h> +#include <errno.h> +#include <error.h> +#include <fcntl.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <sys/wait.h> +#include "prelink.h" +#include "reloc-info.h" + +static struct + { + const char *prefix; + unsigned char prefix_len, st_info, check_pltref; + } +specials[] = + { + /* G++ 3.0 ABI. */ + /* Virtual table. */ + { "_ZTV", 4, GELF_ST_INFO (STB_WEAK, STT_OBJECT), 1 }, + /* Typeinfo. */ + { "_ZTI", 4, GELF_ST_INFO (STB_WEAK, STT_OBJECT), 0 }, + /* G++ 2.96-RH ABI. */ + /* Virtual table. */ + { "__vt_", 5, GELF_ST_INFO (STB_WEAK, STT_OBJECT), 0 }, + { NULL, 0, 0, 0 } + }; + +struct find_cxx_sym_valsize +{ + GElf_Addr start; + GElf_Addr end; + unsigned int idx; + unsigned char mark; +}; + +struct find_cxx_sym_cache +{ + Elf_Data *symtab, *strtab; + int symsec, strsec, count; + struct find_cxx_sym_valsize vals[]; +}; + +struct find_cxx_sym +{ + DSO *dso; + int n; + struct find_cxx_sym_cache *cache; + struct prelink_entry *ent; + Elf_Data *symtab, *strtab; + int symsec, strsec; + int lastndx; + GElf_Sym sym; +}; + +static int +cachecmp (const void *a, const void *b) +{ + GElf_Addr va = ((const struct find_cxx_sym_valsize *) a)->start; + GElf_Addr vb = ((const struct find_cxx_sym_valsize *) b)->start; + + if (va < vb) + return -1; + if (va > vb) + return 1; + + va = ((const struct find_cxx_sym_valsize *) a)->end; + vb = ((const struct find_cxx_sym_valsize *) b)->end; + + if (va < vb) + return -1; + + return va > vb; +} + +static struct find_cxx_sym_cache * +create_cache (DSO *dso, int plt) +{ + Elf_Data *symtab, *strtab; + Elf_Scn *scn; + int symsec, strsec, ndx, dndx, maxndx; + struct find_cxx_sym_cache *cache; + GElf_Addr top; + + symsec = addr_to_sec (dso, dso->info[DT_SYMTAB]); + if (symsec == -1) + return (struct find_cxx_sym_cache *) -1UL; + scn = dso->scn[symsec]; + symtab = elf_getdata (scn, NULL); + assert (elf_getdata (scn, symtab) == NULL); + strsec = addr_to_sec (dso, dso->info[DT_STRTAB]); + if (strsec == -1) + return (struct find_cxx_sym_cache *) -1UL; + scn = dso->scn[strsec]; + strtab = elf_getdata (scn, NULL); + assert (elf_getdata (scn, strtab) == NULL); + maxndx = symtab->d_size / dso->shdr[symsec].sh_entsize; + + cache = malloc (sizeof (*cache) + sizeof (cache->vals[0]) * maxndx); + if (cache == NULL) + { + error (0, ENOMEM, "%s: Could load symbol table", dso->filename); + return NULL; + } + + cache->symsec = symsec; + cache->strsec = strsec; + cache->symtab = symtab; + cache->strtab = strtab; + for (ndx = 0, dndx = 0; ndx < maxndx; ++ndx) + { + GElf_Sym sym; + const char *name; + int k; + + gelfx_getsym (dso->elf, symtab, ndx, &sym); + if (plt) + { + if (sym.st_shndx != SHN_UNDEF || sym.st_value == 0) + continue; + } + else if (sym.st_shndx == SHN_UNDEF) + continue; + cache->vals[dndx].start = sym.st_value; + cache->vals[dndx].end = sym.st_value + sym.st_size; + cache->vals[dndx].idx = ndx; + cache->vals[dndx].mark = 0; + name = (const char *) strtab->d_buf + sym.st_name; + if (!plt && ELF32_ST_VISIBILITY (sym.st_other) == STV_DEFAULT) + for (k = 0; specials[k].prefix; ++k) + if (sym.st_info == specials[k].st_info + && strncmp (name, specials[k].prefix, + specials[k].prefix_len) == 0) + { + cache->vals[dndx].mark = 1; + break; + } + ++dndx; + } + + maxndx = dndx; + qsort (cache->vals, maxndx, sizeof (cache->vals[0]), cachecmp); + + if (!plt) + { + for (top = 0, ndx = 0; ndx < maxndx; ++ndx) + { + if (cache->vals[ndx].start < top + || (ndx < maxndx - 1 + && cache->vals[ndx].end > cache->vals[ndx + 1].start)) + cache->vals[ndx].mark = 0; + if (cache->vals[ndx].end > top) + top = cache->vals[ndx].end; + } + + for (ndx = dndx = 0; ndx < maxndx; ++ndx) + if (cache->vals[ndx].mark) + cache->vals[dndx++] = cache->vals[ndx]; + } + cache->count = dndx; + return cache; +} + +static int +find_cxx_sym (struct prelink_info *info, GElf_Addr addr, + struct find_cxx_sym *fcs, int reloc_size, + struct find_cxx_sym_cache **cache) +{ + int n, ndeps = info->ent->ndepends + 1; + unsigned int hi, lo, mid; + DSO *dso = NULL; + struct find_cxx_sym_cache *c; + + if (fcs->dso == NULL + || addr < fcs->dso->base + || addr >= fcs->dso->end) + { + for (n = 1; n < ndeps; ++n) + { + dso = info->dsos[n]; + if (addr >= dso->base + && addr < dso->end) + break; + } + + if (n == ndeps + && addr >= info->dso->base + && addr < info->dso->end) + { + n = 0; + dso = info->dso; + } + + assert (n < ndeps); + + if (cache[n] == NULL) + { + cache[n] = create_cache (dso, 0); + if (cache[n] == NULL) + return -2; + } + if (cache[n] == (struct find_cxx_sym_cache *) -1UL) + return -1; + + fcs->n = n; + fcs->ent = n ? info->ent->depends[n - 1] : info->ent; + fcs->dso = dso; + fcs->cache = cache[n]; + fcs->symsec = fcs->cache->symsec; + fcs->symtab = fcs->cache->symtab; + fcs->strsec = fcs->cache->strsec; + fcs->strtab = fcs->cache->strtab; + fcs->lastndx = -1; + } + else + dso = fcs->dso; + + c = fcs->cache; + lo = 0; + hi = c->count; + if (fcs->lastndx != -1) + { + if (c->vals[fcs->lastndx].start <= addr) + { + lo = fcs->lastndx; + if (hi - lo >= 16) + { + if (c->vals[lo + 2].start > addr) + hi = lo + 2; + else if (c->vals[lo + 15].start > addr) + hi = lo + 15; + } + } + else + { + hi = fcs->lastndx; + if (hi >= 15) + { + if (c->vals[hi - 2].start <= addr) + lo = hi - 2; + else if (c->vals[hi - 15].start <= addr) + lo = hi - 15; + } + } + } + while (lo < hi) + { + mid = (lo + hi) / 2; + if (c->vals[mid].start <= addr) + { + if (c->vals[mid].end >= addr + reloc_size) + { + gelfx_getsym (dso->elf, fcs->symtab, c->vals[mid].idx, + &fcs->sym); + fcs->lastndx = mid; + return c->vals[mid].idx; + } + lo = mid + 1; + } + else + hi = mid; + } + + return -1; +} + +/* The idea here is that C++ virtual tables are always emitted + in .gnu.linkonce.d.* sections as WEAK symbols and they + need to be the same. + We check if they are and if yes, remove conflicts against + virtual tables which will not be used. */ + +int +remove_redundant_cxx_conflicts (struct prelink_info *info) +{ + int i, j, k, n, o, state, removed = 0; + int ndx, sec; + unsigned int hi, lo, mid; + int reloc_type, reloc_size; + struct find_cxx_sym fcs1, fcs2; + char *mem1, *mem2; + const char *name = NULL, *secname = NULL; + GElf_Addr symtab_start; + GElf_Word symoff; + Elf_Data *binsymtab = NULL; + int binsymtabsec; + struct prelink_conflict *conflict; + struct find_cxx_sym_cache **cache; + struct find_cxx_sym_cache *binsymcache = NULL; + int ret = 0; + int rtype_class_valid; + + /* Don't bother doing this for non-C++ programs. */ + for (i = 0; i < info->ent->ndepends; ++i) + if (strstr (info->ent->depends[i]->canon_filename, "libstdc++")) + break; + if (i == info->ent->ndepends) + return 0; + + binsymtabsec = addr_to_sec (info->dso, info->dso->info[DT_SYMTAB]); + if (binsymtabsec != -1) + { + Elf_Scn *scn = info->dso->scn[binsymtabsec]; + + binsymtab = elf_getdata (scn, NULL); + assert (elf_getdata (scn, binsymtab) == NULL); + } + + rtype_class_valid = info->dso->arch->rtype_class_valid; + + state = 0; + memset (&fcs1, 0, sizeof (fcs1)); + memset (&fcs2, 0, sizeof (fcs2)); + cache = alloca (sizeof (struct find_cxx_sym_cache *) + * (info->ent->ndepends + 1)); + memset (cache, '\0', sizeof (struct find_cxx_sym_cache *) + * (info->ent->ndepends + 1)); + for (i = 0; i < info->conflict_rela_size; ++i) + { + size_t cidx; + + reloc_type = reloc_r_type (info->dso, info->conflict_rela[i].r_info); + reloc_size = info->dso->arch->reloc_size (reloc_type); + + if (reloc_r_sym (info->dso, info->conflict_rela[i].r_info) != 0) + continue; + + if (state + && fcs1.sym.st_value <= info->conflict_rela[i].r_offset + && fcs1.sym.st_value + fcs1.sym.st_size + >= info->conflict_rela[i].r_offset + reloc_size) + { + if (state == 3) + goto remove_noref; + if (state == 2) + goto check_pltref; + continue; + } + + n = find_cxx_sym (info, info->conflict_rela[i].r_offset, + &fcs1, reloc_size, cache); + + state = 0; + if (n == -1) + continue; + if (n == -2) + { + ret = 1; + goto out_free_cache; + } + state = 1; + sec = addr_to_sec (fcs1.dso, fcs1.sym.st_value); + if (sec == -1) + continue; + secname = strptr (fcs1.dso, fcs1.dso->ehdr.e_shstrndx, + fcs1.dso->shdr[sec].sh_name); + if (secname == NULL) + continue; + + name = (const char *) fcs1.strtab->d_buf + fcs1.sym.st_name; + + for (k = 0; specials[k].prefix; ++k) + if (ELF32_ST_VISIBILITY (fcs1.sym.st_other) == STV_DEFAULT + && fcs1.sym.st_info == specials[k].st_info + && strncmp (name, specials[k].prefix, specials[k].prefix_len) == 0) + break; + + if (specials[k].prefix == NULL) + continue; + + if (strcmp (secname, ".data") != 0 + && strcmp (secname, ".data.rel.ro") != 0 + && strcmp (secname, ".sdata") != 0) + continue; + + if (specials[k].check_pltref) + state = 2; + + symtab_start = fcs1.dso->shdr[fcs1.symsec].sh_addr - fcs1.dso->base; + symoff = symtab_start + n * fcs1.dso->shdr[fcs1.symsec].sh_entsize; + + cidx = 0; + if (info->conflicts[fcs1.n].hash != &info->conflicts[fcs1.n].first) + cidx = symoff % 251; + for (conflict = info->conflicts[fcs1.n].hash[cidx]; conflict; + conflict = conflict->next) + if (conflict->symoff == symoff + && conflict->reloc_class == rtype_class_valid) + break; + + if (conflict == NULL) + goto check_pltref; + + if (conflict->conflict.ent != fcs1.ent + || fcs1.dso->base + conflict->conflictval != fcs1.sym.st_value) + goto check_pltref; + + if (verbose > 4) + error (0, 0, "Possible C++ conflict removal from unreferenced table at %s:%s+%d", + fcs1.dso->filename, name, + (int) (info->conflict_rela[i].r_offset - fcs1.sym.st_value)); + + /* Limit size slightly. */ + if (fcs1.sym.st_size > 16384) + goto check_pltref; + + o = find_cxx_sym (info, conflict->lookup.ent->base + conflict->lookupval, + &fcs2, fcs1.sym.st_size, cache); + + if (o == -2) + { + ret = 1; + goto out_free_cache; + } + + if (o == -1 + || fcs1.sym.st_size != fcs2.sym.st_size + || fcs1.sym.st_info != fcs2.sym.st_info + || ELF32_ST_VISIBILITY (fcs2.sym.st_other) != STV_DEFAULT + || strcmp (name, (char *) fcs2.strtab->d_buf + fcs2.sym.st_name) != 0) + goto check_pltref; + + mem1 = malloc (fcs1.sym.st_size * 2); + if (mem1 == NULL) + { + error (0, ENOMEM, "%s: Could not compare %s arrays", + info->dso->filename, name); + ret = 1; + goto out_free_cache; + } + + mem2 = mem1 + fcs1.sym.st_size; + + if (get_relocated_mem (info, fcs1.dso, fcs1.sym.st_value, mem1, + fcs1.sym.st_size, 0) + || get_relocated_mem (info, fcs2.dso, fcs2.sym.st_value, mem2, + fcs1.sym.st_size, 0) + || memcmp (mem1, mem2, fcs1.sym.st_size) != 0) + { + free (mem1); + goto check_pltref; + } + + free (mem1); + + state = 3; + +remove_noref: + if (verbose > 3) + error (0, 0, "Removing C++ conflict from unreferenced table at %s:%s+%d", + fcs1.dso->filename, name, + (int) (info->conflict_rela[i].r_offset - fcs1.sym.st_value)); + + info->conflict_rela[i].r_info = + reloc_r_info (info->dso, 1, + reloc_r_type (info->dso, info->conflict_rela[i].r_info)); + ++removed; + continue; + +check_pltref: + /* If the binary calls directly (or takes its address) one of the + methods in a virtual table, but doesn't define it, there is no + need to leave conflicts in the virtual table which will only + slow down the code (as it has to hop through binary's .plt + back to the method). */ + if (state != 2 + || info->conflict_rela[i].r_addend < info->dso->base + || info->conflict_rela[i].r_addend >= info->dso->end + || binsymtab == NULL) + continue; + + if (binsymcache == NULL) + { + binsymcache = create_cache (info->dso, 1); + if (binsymcache == NULL) + { + ret = 1; + goto out_free_cache; + } + } + if (binsymcache == (struct find_cxx_sym_cache *) -1UL) + continue; + + lo = 0; + mid = 0; + hi = binsymcache->count; + while (lo < hi) + { + mid = (lo + hi) / 2; + if (binsymcache->vals[mid].start < info->conflict_rela[i].r_addend) + lo = mid + 1; + else if (binsymcache->vals[mid].start + > info->conflict_rela[i].r_addend) + hi = mid; + else + break; + } + if (lo >= hi) + continue; + + while (mid > 0 && binsymcache->vals[mid - 1].start + == info->conflict_rela[i].r_addend) + --mid; + + while (mid < binsymcache->count + && binsymcache->vals[mid].start + == info->conflict_rela[i].r_addend) + { + GElf_Sym sym; + + ndx = binsymcache->vals[mid].idx; + mid++; + gelfx_getsym (info->dso->elf, binsymtab, ndx, &sym); + assert (sym.st_value == info->conflict_rela[i].r_addend); + if (sym.st_shndx == SHN_UNDEF && sym.st_value) + { + struct prelink_symbol *s; + size_t maxidx, l; + + if (verbose > 4) + error (0, 0, "Possible C++ conflict removal due to reference to binary's .plt at %s:%s+%d", + fcs1.dso->filename, name, + (int) (info->conflict_rela[i].r_offset + - fcs1.sym.st_value)); + + for (s = &info->symbols[ndx]; s; s = s->next) + if (s->reloc_class == RTYPE_CLASS_PLT) + break; + + if (s == NULL) + break; + + maxidx = 1; + if (info->conflicts[fcs1.n].hash + != &info->conflicts[fcs1.n].first) + { + if (info->conflicts[fcs1.n].hash2 == NULL) + { + info->conflicts[fcs1.n].hash2 + = calloc (sizeof (struct prelink_conflict *), 251); + if (info->conflicts[fcs1.n].hash2 != NULL) + { + for (l = 0; l < 251; l++) + for (conflict = info->conflicts[fcs1.n].hash[l]; + conflict; conflict = conflict->next) + if (conflict->reloc_class == rtype_class_valid + && conflict->conflict.ent) + { + size_t ccidx + = (conflict->lookup.ent->base + + conflict->lookupval) % 251; + conflict->next2 + = info->conflicts[fcs1.n].hash2[ccidx]; + info->conflicts[fcs1.n].hash2[ccidx] + = conflict; + } + } + } + if (info->conflicts[fcs1.n].hash2 != NULL) + { + size_t ccidx = info->conflict_rela[i].r_addend % 251; + for (conflict = info->conflicts[fcs1.n].hash2[ccidx]; + conflict; conflict = conflict->next2) + if (conflict->lookup.ent->base + conflict->lookupval + == info->conflict_rela[i].r_addend + && (conflict->conflict.ent->base + + conflict->conflictval + == s->u.ent->base + s->value)) + goto pltref_remove; + break; + } + maxidx = 251; + } + + for (l = 0; l < maxidx; l++) + for (conflict = info->conflicts[fcs1.n].hash[l]; + conflict; conflict = conflict->next) + if (conflict->lookup.ent->base + conflict->lookupval + == info->conflict_rela[i].r_addend + && conflict->conflict.ent + && (conflict->conflict.ent->base + + conflict->conflictval == s->u.ent->base + s->value) + && conflict->reloc_class == rtype_class_valid) + { +pltref_remove: + if (verbose > 3) + error (0, 0, "Removing C++ conflict due to reference to binary's .plt at %s:%s+%d", + fcs1.dso->filename, name, + (int) (info->conflict_rela[i].r_offset + - fcs1.sym.st_value)); + + info->conflict_rela[i].r_info = + reloc_r_info (info->dso, 1, reloc_r_type (info->dso, info->conflict_rela[i].r_info)); + ++removed; + goto pltref_check_done; + } + +pltref_check_done: + break; + } + } + } + + if (removed) + { + for (i = 0, j = 0; i < info->conflict_rela_size; ++i) + if (reloc_r_sym (info->dso, info->conflict_rela[i].r_info) == 0) + { + if (i != j) + info->conflict_rela[j] = info->conflict_rela[i]; + ++j; + } + info->conflict_rela_size = j; + } + +out_free_cache: + for (i = 0; i < info->ent->ndepends + 1; i++) + if (cache[i] && cache[i] != (struct find_cxx_sym_cache *) -1UL) + free (cache[i]); + if (binsymcache && binsymcache != (struct find_cxx_sym_cache *) -1UL) + free (binsymcache); + return ret; +} |