Commit 02b54001 authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

objtool: Shrink elf hash nodes 

Instead of using hlist for the 'struct elf' hashes, use a custom
single-linked list scheme.

With allyesconfig + CONFIG_DEBUG_INFO:

- Before: peak heap memory consumption: 36.89G
- After:  peak heap memory consumption: 35.12G

Link: https://lore.kernel.org/r/6e8cd305ed22e743c30d6e72cfdc1be20fb94cd4.1685464332.git.jpoimboe@kernel.org


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent 890f10a4

tools/objtool/elf.c

+44 −8
Original line number Diff line number Diff line
@@ -32,16 +32,52 @@ static inline u32 str_hash(const char *str) 
#define __elf_table(name)	(elf->name##_hash)

#define __elf_bits(name)	(elf->name##_bits)



#define __elf_table_entry(name, key) \

	__elf_table(name)[hash_min(key, __elf_bits(name))]



#define elf_hash_add(name, node, key)					\

	hlist_add_head(node, &__elf_table(name)[hash_min(key, __elf_bits(name))])

({									\

	struct elf_hash_node *__node = node;				\

	__node->next = __elf_table_entry(name, key);			\

	__elf_table_entry(name, key) = __node;				\

})



static inline void __elf_hash_del(struct elf_hash_node *node,

				  struct elf_hash_node **head)

{

	struct elf_hash_node *cur, *prev;



	if (node == *head) {

		*head = node->next;

		return;

	}



	for (prev = NULL, cur = *head; cur; prev = cur, cur = cur->next) {

		if (cur == node) {

			prev->next = cur->next;

			break;

		}

	}

}



#define elf_hash_del(name, node, key) \

	__elf_hash_del(node, &__elf_table_entry(name, key))



#define elf_list_entry(ptr, type, member)				\

({									\

	typeof(ptr) __ptr = (ptr);					\

	__ptr ? container_of(__ptr, type, member) : NULL;		\

})



#define elf_hash_for_each_possible(name, obj, member, key)		\

	hlist_for_each_entry(obj, &__elf_table(name)[hash_min(key, __elf_bits(name))], member)

	for (obj = elf_list_entry(__elf_table_entry(name, key), typeof(*obj), member); \

	     obj;							\

	     obj = elf_list_entry(obj->member.next, typeof(*(obj)), member))



#define elf_alloc_hash(name, size) \

({ \

	__elf_bits(name) = max(10, ilog2(size)); \

	__elf_table(name) = mmap(NULL, sizeof(struct hlist_head) << __elf_bits(name), \

	__elf_table(name) = mmap(NULL, sizeof(struct elf_hash_node *) << __elf_bits(name), \

				 PROT_READ|PROT_WRITE, \

				 MAP_PRIVATE|MAP_ANON, -1, 0); \

	if (__elf_table(name) == (void *)-1L) { \
@@ -713,10 +749,10 @@ __elf_create_symbol(struct elf *elf, struct symbol *sym) 
	first_non_local = symtab->sh.sh_info;

	old = find_symbol_by_index(elf, first_non_local);

	if (old) {

		old->idx = new_idx;



		hlist_del(&old->hash);

		elf_hash_add(symbol, &old->hash, old->idx);

		elf_hash_del(symbol, &old->hash, old->idx);

		elf_hash_add(symbol, &old->hash, new_idx);

		old->idx = new_idx;



		if (elf_update_symbol(elf, symtab, symtab_shndx, old)) {

			WARN("elf_update_symbol move");

tools/objtool/include/objtool/elf.h

+14 −10
Original line number Diff line number Diff line
@@ -26,10 +26,14 @@ 
#define ELF_C_READ_MMAP ELF_C_READ

#endif



struct elf_hash_node {

	struct elf_hash_node *next;

};



struct section {

	struct list_head list;

	struct hlist_node hash;

	struct hlist_node name_hash;

	struct elf_hash_node hash;

	struct elf_hash_node name_hash;

	GElf_Shdr sh;

	struct rb_root_cached symbol_tree;

	struct list_head symbol_list;
@@ -45,8 +49,8 @@ struct section { 
struct symbol {

	struct list_head list;

	struct rb_node node;

	struct hlist_node hash;

	struct hlist_node name_hash;

	struct elf_hash_node hash;

	struct elf_hash_node name_hash;

	GElf_Sym sym;

	struct section *sec;

	char *name;
@@ -67,7 +71,7 @@ struct symbol { 
};



struct reloc {

	struct hlist_node hash;

	struct elf_hash_node hash;

	union {

		GElf_Rela rela;

		GElf_Rel  rel;
@@ -93,11 +97,11 @@ struct elf { 
	int section_name_bits;

	int reloc_bits;



	struct hlist_head *symbol_hash;

	struct hlist_head *symbol_name_hash;

	struct hlist_head *section_hash;

	struct hlist_head *section_name_hash;

	struct hlist_head *reloc_hash;

	struct elf_hash_node **symbol_hash;

	struct elf_hash_node **symbol_name_hash;

	struct elf_hash_node **section_hash;

	struct elf_hash_node **section_name_hash;

	struct elf_hash_node **reloc_hash;



	struct section *section_data;

	struct symbol *symbol_data;