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objtool: Allocate multiple structures with calloc() 

By using calloc() instead of malloc() in a loop, libc does not have to
keep around bookkeeping information for each single structure.

This reduces maximum memory usage while processing vmlinux.o from
3153325 KB to 3035668 KB (-3.7%) on my notebooks "localmodconfig".

Note this introduces memory leaks, because some additional structs get
added to the lists later after reading the symbols and sections from the
original object.  Luckily we don't really care about memory leaks in
objtool.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20221216-objtool-memory-v2-3-17968f85a464@weissschuh.net
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Thomas Weißschuh 2022-12-27 16:00:59 +00:00 committed by Josh Poimboeuf
parent cfd66e8179
commit 8045b8f0b1
2 changed files with 25 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
tools/objtool/elf.c
View File

@ -284,13 +284,13 @@ static int read_sections(struct elf *elf)
!elf_alloc_hash(section_name, sections_nr))
return -1;
elf->section_data = calloc(sections_nr, sizeof(*sec));
if (!elf->section_data) {
perror("calloc");
return -1;
}
for (i = 0; i < sections_nr; i++) {
sec = malloc(sizeof(*sec));
if (!sec) {
perror("malloc");
return -1;
}
memset(sec, 0, sizeof(*sec));
sec = &elf->section_data[i];
INIT_LIST_HEAD(&sec->symbol_list);
INIT_LIST_HEAD(&sec->reloc_list);
@ -422,13 +422,13 @@ static int read_symbols(struct elf *elf)
!elf_alloc_hash(symbol_name, symbols_nr))
return -1;
elf->symbol_data = calloc(symbols_nr, sizeof(*sym));
if (!elf->symbol_data) {
perror("calloc");
return -1;
}
for (i = 0; i < symbols_nr; i++) {
sym = malloc(sizeof(*sym));
if (!sym) {
perror("malloc");
return -1;
}
memset(sym, 0, sizeof(*sym));
sym = &elf->symbol_data[i];
sym->idx = i;
@ -918,13 +918,13 @@ static int read_relocs(struct elf *elf)
sec->base->reloc = sec;
nr_reloc = 0;
sec->reloc_data = calloc(sec->sh.sh_size / sec->sh.sh_entsize, sizeof(*reloc));
if (!sec->reloc_data) {
perror("calloc");
return -1;
}
for (i = 0; i < sec->sh.sh_size / sec->sh.sh_entsize; i++) {
reloc = malloc(sizeof(*reloc));
if (!reloc) {
perror("malloc");
return -1;
}
memset(reloc, 0, sizeof(*reloc));
reloc = &sec->reloc_data[i];
switch (sec->sh.sh_type) {
case SHT_REL:
if (read_rel_reloc(sec, i, reloc, &symndx))
@ -1453,16 +1453,16 @@ void elf_close(struct elf *elf)
list_for_each_entry_safe(sym, tmpsym, &sec->symbol_list, list) {
list_del(&sym->list);
hash_del(&sym->hash);
free(sym);
}
list_for_each_entry_safe(reloc, tmpreloc, &sec->reloc_list, list) {
list_del(&reloc->list);
hash_del(&reloc->hash);
free(reloc);
}
list_del(&sec->list);
free(sec);
free(sec->reloc_data);
}
free(elf->symbol_data);
free(elf->section_data);
free(elf);
}

4
tools/objtool/include/objtool/elf.h
View File

@ -39,6 +39,7 @@ struct section {
char *name;
int idx;
bool changed, text, rodata, noinstr, init, truncate;
struct reloc *reloc_data;
};
struct symbol {
@ -104,6 +105,9 @@ struct elf {
struct hlist_head *section_hash;
struct hlist_head *section_name_hash;
struct hlist_head *reloc_hash;
struct section *section_data;
struct symbol *symbol_data;
};
#define OFFSET_STRIDE_BITS 4