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Merge pull request #201 from spartacus06/delay-reindexing-reordering

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delay element reindexing and symbol reordering
This commit is contained in:
Josh Poimboeuf 2014-05-23 09:09:36 -05:00
commit 56fbd41eeb
1 changed files with 106 additions and 136 deletions
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242
kpatch-build/create-diff-object.c
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@ -137,7 +137,7 @@ struct kpatch_elf {
Elf *elf;
struct list_head sections;
struct list_head symbols;
int fd, sections_nr;
int fd;
};
/*******************
@ -279,7 +279,6 @@ void kpatch_create_section_list(struct kpatch_elf *kelf)
if (elf_getshdrnum(kelf->elf, &sections_nr))
ERROR("elf_getshdrnum");
kelf->sections_nr = sections_nr;
/*
* elf_getshdrnum() includes section index 0 but elf_nextscn
@ -697,10 +696,9 @@ void kpatch_dump_kelf(struct kpatch_elf *kelf)
printf(", base-> %s\n", sec->base->name);
printf("rela section expansion\n");
list_for_each_entry(rela, &sec->relas, list) {
printf("sym %lu, offset %d, type %d, %s %s %d\n",
GELF_R_SYM(rela->rela.r_info),
rela->offset, rela->type,
rela->sym->name,
printf("sym %d, offset %d, type %d, %s %s %d\n",
rela->sym->index, rela->offset,
rela->type, rela->sym->name,
(rela->addend < 0)?"-":"+",
abs(rela->addend));
}
@ -782,7 +780,7 @@ out:
return;
}
void kpatch_include_standard_sections(struct kpatch_elf *kelf)
void kpatch_include_standard_elements(struct kpatch_elf *kelf)
{
struct section *sec;
@ -793,6 +791,9 @@ void kpatch_include_standard_sections(struct kpatch_elf *kelf)
!strcmp(sec->name, ".symtab"))
sec->include = 1;
}
/* include the NULL symbol */
list_entry(kelf->symbols.next, struct symbol, list)->include = 1;
}
int kpatch_include_changed_functions(struct kpatch_elf *kelf)
@ -818,14 +819,13 @@ int kpatch_include_changed_functions(struct kpatch_elf *kelf)
return changed_nr;
}
int kpatch_migrate_included_symbols(int startndx, struct kpatch_elf *src,
struct kpatch_elf *dst,
int (*select)(struct symbol *))
void kpatch_migrate_included_symbols(struct list_head *src,
struct list_head *dst,
int (*select)(struct symbol *))
{
struct symbol *sym, *safe;
int index = startndx;
list_for_each_entry_safe(sym, safe, &src->symbols, list) {
list_for_each_entry_safe(sym, safe, src, list) {
if (!sym->include)
continue;
@ -833,24 +833,13 @@ int kpatch_migrate_included_symbols(int startndx, struct kpatch_elf *src,
continue;
list_del(&sym->list);
list_add_tail(&sym->list, &dst->symbols);
sym->index = index++;
/*
* By this point, the included sections have already been
* reindexed. Update the symbol section header index.
*/
if (sym->sec) {
if (sym->sec->include)
sym->sym.st_shndx = sym->sec->index;
else {
sym->sec = NULL;
sym->sym.st_shndx = SHN_UNDEF;
}
}
list_add_tail(&sym->list, dst);
}
}
return index;
int is_null_sym(struct symbol *sym)
{
return sym->bind == STB_LOCAL && sym->sym.st_shndx == SHN_UNDEF;
}
int is_file_sym(struct symbol *sym)
@ -868,27 +857,11 @@ int is_local_sym(struct symbol *sym)
return sym->bind == STB_LOCAL;
}
void kpatch_generate_output(struct kpatch_elf *kelf, struct kpatch_elf **kelfout)
void kpatch_migrate_included_elements(struct kpatch_elf *kelf, struct kpatch_elf **kelfout)
{
int sections_nr = 0, symbols_nr = 0, index;
struct section *sec, *safe;
struct symbol *sym;
struct section *sec, *safesec;
struct symbol *sym, *safesym;
struct kpatch_elf *out;
struct list_head *nullsym;
/* count output sections */
list_for_each_entry(sec, &kelf->sections, list)
if (sec->include)
sections_nr++;
log_debug("outputting %d sections\n",sections_nr);
/* count output symbols */
list_for_each_entry(sym, &kelf->symbols, list)
if (sym->include)
symbols_nr++;
log_debug("outputting %d symbols\n",symbols_nr);
/* allocate output kelf */
out = malloc(sizeof(*out));
@ -898,42 +871,67 @@ void kpatch_generate_output(struct kpatch_elf *kelf, struct kpatch_elf **kelfout
INIT_LIST_HEAD(&out->sections);
INIT_LIST_HEAD(&out->symbols);
/* copy to output kelf sections, link to kelf, and reindex */
index = 1;
list_for_each_entry_safe(sec, safe, &kelf->sections, list) {
/* migrate included sections from kelf to out */
list_for_each_entry_safe(sec, safesec, &kelf->sections, list) {
if (!sec->include)
continue;
list_del(&sec->list);
list_add_tail(&sec->list, &out->sections);
sec->index = index++;
sec->index = 0;
}
out->sections_nr = index;
/*
* Copy functions to the output kelf and reindex. Once the symbol is
* copied, its include field is set to zero so it isn't copied again
* by a subsequent kpatch_migrate_included_symbols() call.
*/
/* copy null symbol first */
nullsym = kelf->symbols.next;
list_del(nullsym);
list_add(nullsym, &out->symbols);
index = 1;
/* copy (LOCAL) FILE sym */
index = kpatch_migrate_included_symbols(index, kelf, out, is_file_sym);
/* copy LOCAL FUNC syms */
index = kpatch_migrate_included_symbols(index, kelf, out, is_local_func_sym);
/* copy all other LOCAL syms */
index = kpatch_migrate_included_symbols(index, kelf, out, is_local_sym);
/* copy all other (GLOBAL) syms */
index = kpatch_migrate_included_symbols(index, kelf, out, NULL);
/* migrate included symbols from kelf to out */
list_for_each_entry_safe(sym, safesym, &kelf->symbols, list) {
if (!sym->include)
continue;
list_del(&sym->list);
list_add_tail(&sym->list, &out->symbols);
sym->index = 0;
if (sym->sec && !sym->sec->include)
/* break link to non-included section */
sym->sec = NULL;
}
*kelfout = out;
}
void kpatch_reorder_symbols(struct kpatch_elf *kelf)
{
LIST_HEAD(symbols);
/* migrate NULL sym */
kpatch_migrate_included_symbols(&kelf->symbols, &symbols, is_null_sym);
/* migrate LOCAL FILE sym */
kpatch_migrate_included_symbols(&kelf->symbols, &symbols, is_file_sym);
/* migrate LOCAL FUNC syms */
kpatch_migrate_included_symbols(&kelf->symbols, &symbols, is_local_func_sym);
/* migrate all other LOCAL syms */
kpatch_migrate_included_symbols(&kelf->symbols, &symbols, is_local_sym);
/* migrate all other (GLOBAL) syms */
kpatch_migrate_included_symbols(&kelf->symbols, &symbols, NULL);
list_replace(&symbols, &kelf->symbols);
}
void kpatch_reindex_elements(struct kpatch_elf *kelf)
{
struct section *sec;
struct symbol *sym;
int index;
index = 1; /* elf write function handles NULL section 0 */
list_for_each_entry(sec, &kelf->sections, list)
sec->index = index++;
index = 0;
list_for_each_entry(sym, &kelf->symbols, list) {
sym->index = index++;
if (sym->sec)
sym->sym.st_shndx = sym->sec->index;
}
}
void kpatch_write_inventory_file(struct kpatch_elf *kelf, char *outfile)
{
FILE *out;
@ -1152,22 +1150,6 @@ void kpatch_regenerate_parainstructions_sections(struct kpatch_elf *kelf)
sec->base->data->d_size = offset;
}
void kpatch_update_rela_section_headers(struct kpatch_elf *kelf)
{
struct section *sec;
int link;
link = find_section_by_name(&kelf->sections, ".symtab")->index;
/* update rela section header link and info fields after reindexing */
list_for_each_entry(sec, &kelf->sections, list) {
if (is_rela_section(sec)) {
sec->sh.sh_link = link;
sec->sh.sh_info = sec->base->index;
}
}
}
void print_strtab(char *buf, size_t size)
{
int i;
@ -1311,11 +1293,6 @@ void kpatch_create_symtab(struct kpatch_elf *kelf)
symtab->data->d_buf = buf;
symtab->data->d_size = size;
symtab->sh.sh_link =
find_section_by_name(&kelf->sections, ".strtab")->index;
symtab->sh.sh_info =
find_section_by_name(&kelf->sections, ".shstrtab")->index;
}
void kpatch_create_patches_sections(struct kpatch_elf *kelf,
@ -1343,7 +1320,6 @@ void kpatch_create_patches_sections(struct kpatch_elf *kelf,
if (!patches)
ERROR("malloc");
sec->name = ".kpatch.patches";
sec->index = kelf->sections_nr++;
/* set data */
sec->data = malloc(sizeof(*sec->data));
@ -1365,7 +1341,6 @@ void kpatch_create_patches_sections(struct kpatch_elf *kelf,
/* allocate section resources */
ALLOC_LINK(relasec, &kelf->sections);
relasec->name = ".rela.kpatch.patches";
relasec->index = kelf->sections_nr++;
relasec->base = sec;
INIT_LIST_HEAD(&relasec->relas);
@ -1379,10 +1354,6 @@ void kpatch_create_patches_sections(struct kpatch_elf *kelf,
relasec->sh.sh_entsize = sizeof(GElf_Rela);
relasec->sh.sh_addralign = 8;
relasec->sh.sh_link =
find_section_by_name(&kelf->sections, ".symtab")->index;
relasec->sh.sh_info = sec->index;
/* populate sections */
index = 0;
list_for_each_entry(sym, &kelf->symbols, list) {
@ -1460,7 +1431,6 @@ void kpatch_create_dynamic_rela_sections(struct kpatch_elf *kelf,
if (!dynrelas)
ERROR("malloc");
sec->name = ".kpatch.dynrelas";
sec->index = kelf->sections_nr++;
/* set data */
sec->data = malloc(sizeof(*sec->data));
@ -1482,7 +1452,6 @@ void kpatch_create_dynamic_rela_sections(struct kpatch_elf *kelf,
/* allocate section resources */
ALLOC_LINK(relasec, &kelf->sections);
relasec->name = ".rela.kpatch.dynrelas";
relasec->index = kelf->sections_nr++;
relasec->base = sec;
INIT_LIST_HEAD(&relasec->relas);
@ -1496,10 +1465,6 @@ void kpatch_create_dynamic_rela_sections(struct kpatch_elf *kelf,
relasec->sh.sh_entsize = sizeof(GElf_Rela);
relasec->sh.sh_addralign = 8;
relasec->sh.sh_link =
find_section_by_name(&kelf->sections, ".symtab")->index;
relasec->sh.sh_info = sec->index;
/* populate sections (reuse sec for iterator here) */
index = 0;
list_for_each_entry(sec, &kelf->sections, list) {
@ -1556,18 +1521,14 @@ void kpatch_create_dynamic_rela_sections(struct kpatch_elf *kelf,
* sections, but the rela entries that referenced them were converted to
* dynrelas and are no longer needed.
*/
void kpatch_strip_unneeded_syms(struct lookup_table *table,
struct kpatch_elf *kelf)
void kpatch_strip_unneeded_syms(struct kpatch_elf *kelf,
struct lookup_table *table)
{
struct symbol *sym, *safe;
int index, first;
first = 1;
list_for_each_entry_safe(sym, safe, &kelf->symbols, list) {
if (first) {
first = 0;
if (sym->bind == STB_LOCAL && sym->sym.st_shndx == SHN_UNDEF)
continue; /* skip NULL symbol */
}
if (sym->type == STT_FILE)
continue;
if (lookup_is_exported_symbol(table, sym->name))
@ -1578,11 +1539,6 @@ void kpatch_strip_unneeded_syms(struct lookup_table *table,
list_del(&sym->list);
free(sym);
}
/* reindex */
index = 0;
list_for_each_entry(sym, &kelf->symbols, list)
sym->index = index++;
}
void kpatch_rebuild_rela_section_data(struct section *sec)
@ -1765,7 +1721,6 @@ void kpatch_elf_teardown(struct kpatch_elf *kelf)
INIT_LIST_HEAD(&kelf->sections);
INIT_LIST_HEAD(&kelf->symbols);
kelf->sections_nr = 0;
}
void kpatch_elf_free(struct kpatch_elf *kelf)
@ -1783,7 +1738,7 @@ int main(int argc, char *argv[])
struct arguments arguments;
int num_changed;
struct lookup_table *vmlinux;
struct section *sec;
struct section *sec, *symtab;
struct symbol *sym;
char *hint;
@ -1829,7 +1784,7 @@ int main(int argc, char *argv[])
kpatch_regenerate_smp_locks_sections(kelf_patched);
kpatch_regenerate_parainstructions_sections(kelf_patched);
kpatch_include_standard_sections(kelf_patched);
kpatch_include_standard_elements(kelf_patched);
num_changed = kpatch_include_changed_functions(kelf_patched);
kpatch_dump_kelf(kelf_patched);
kpatch_verify_patchability(kelf_patched);
@ -1839,12 +1794,8 @@ int main(int argc, char *argv[])
return 3; /* 1 is ERROR, 2 is DIFF_FATAL */
}
/*
* Generate the output elf
*/
/* this is destructive to kelf_patched */
kpatch_generate_output(kelf_patched, &kelf_out);
kpatch_migrate_included_elements(kelf_patched, &kelf_out);
/*
* Teardown kelf_patched since we shouldn't access sections or symbols
@ -1854,8 +1805,6 @@ int main(int argc, char *argv[])
*/
kpatch_elf_teardown(kelf_patched);
kpatch_update_rela_section_headers(kelf_out);
list_for_each_entry(sym, &kelf_out->symbols, list) {
if (sym->type == STT_FILE) {
hint = sym->name;
@ -1864,23 +1813,44 @@ int main(int argc, char *argv[])
}
kpatch_create_patches_sections(kelf_out, vmlinux, hint);
kpatch_create_dynamic_rela_sections(kelf_out, vmlinux, hint);
kpatch_strip_unneeded_syms(vmlinux, kelf_out);
/*
* At this point, the set of output sections and symbols is
* finalized. Reorder the symbols into linker-compliant
* order and index all the symbols and sections. After the
* indexes have been established, update index data
* throughout the structure.
*/
kpatch_reorder_symbols(kelf_out);
kpatch_strip_unneeded_syms(kelf_out, vmlinux);
kpatch_reindex_elements(kelf_out);
/* update symtab section header */
symtab = find_section_by_name(&kelf_out->sections, ".symtab");
symtab->sh.sh_link = find_section_by_name(&kelf_out->sections, ".strtab")->index;
symtab->sh.sh_info = find_section_by_name(&kelf_out->sections, ".shstrtab")->index;
/*
* Update rela section headers and rebuild the rela section data
* buffers from the relas lists.
*/
list_for_each_entry(sec, &kelf_out->sections, list) {
if (!is_rela_section(sec))
continue;
sec->sh.sh_link = symtab->index;
sec->sh.sh_info = sec->base->index;
kpatch_rebuild_rela_section_data(sec);
}
kpatch_create_shstrtab(kelf_out);
kpatch_create_strtab(kelf_out);
kpatch_create_symtab(kelf_out);
kpatch_dump_kelf(kelf_out);
kpatch_write_output_elf(kelf_out, kelf_patched->elf, outfile);
if (arguments.inventory)
kpatch_write_inventory_file(kelf_out, outfile);
/* rebuild the rela section data buffers from their relas lists */
list_for_each_entry(sec, &kelf_out->sections, list)
if (is_rela_section(sec))
kpatch_rebuild_rela_section_data(sec);
kpatch_write_output_elf(kelf_out, kelf_patched->elf, outfile);
kpatch_elf_free(kelf_patched);
kpatch_elf_teardown(kelf_out);
kpatch_elf_free(kelf_out);