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: Josh Poimboeuf <jpoimboe@kernel.org>

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4b0de0e56068a30bd7ca592dc3c5e6bdc63d24c2..04038b1324cf493db5fa0b9abe1c6af0c7196c77 100644 (file)
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -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_hash_add(name, node, key) \
-       hlist_add_head(node, &__elf_table(name)[hash_min(key, __elf_bits(name))])
+#define __elf_table_entry(name, key) \
+       __elf_table(name)[hash_min(key, __elf_bits(name))]
+
+#define elf_hash_add(name, node, key)                                  \
+({                                                                     \
+       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;
 
-#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)
+       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)             \
+       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");

diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 7b808ac3156c681263d3e255aaaa60ffaf0b58e5..03a9040f696ced14fd4c372202c862161485ae49 100644 (file)
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -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;