objtool: Get rid of reloc->list

Now that all relocs are allocated in an array, the linked list is no
longer needed.

With allyesconfig + CONFIG_DEBUG_INFO:

- Before: peak heap memory consumption: 49.02G
- After:  peak heap memory consumption: 45.56G

Link: https://lore.kernel.org/r/71e7a2c017dbc46bb497857ec97d67214f832d10.1685464332.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 5f69d45..19ac53a 100644 (file)
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -293,7 +293,6 @@ static int read_sections(struct elf *elf)
                sec = &elf->section_data[i];
 
                INIT_LIST_HEAD(&sec->symbol_list);
-               INIT_LIST_HEAD(&sec->reloc_list);
 
                s = elf_getscn(elf->elf, i);
                if (!s) {
@@ -333,7 +332,7 @@ static int read_sections(struct elf *elf)
                elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
 
                if (is_reloc_sec(sec))
-                       elf->num_relocs += sec->sh.sh_size / sec->sh.sh_entsize;
+                       elf->num_relocs += sec_num_entries(sec);
        }
 
        if (opts.stats) {
@@ -407,7 +406,7 @@ static int read_symbols(struct elf *elf)
                if (symtab_shndx)
                        shndx_data = symtab_shndx->data;
 
-               symbols_nr = symtab->sh.sh_size / symtab->sh.sh_entsize;
+               symbols_nr = sec_num_entries(symtab);
        } else {
                /*
                 * A missing symbol table is actually possible if it's an empty
@@ -701,7 +700,7 @@ __elf_create_symbol(struct elf *elf, struct symbol *sym)
                return NULL;
        }
 
-       new_idx = symtab->sh.sh_size / symtab->sh.sh_entsize;
+       new_idx = sec_num_entries(symtab);
 
        if (GELF_ST_BIND(sym->sym.st_info) != STB_LOCAL)
                goto non_local;
@@ -816,13 +815,13 @@ static struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
 {
        struct reloc *reloc, empty = { 0 };
 
-       if (reloc_idx >= rsec->sh.sh_size / elf_rela_size(elf)) {
-               WARN("%s: bad reloc_idx %u for %s with size 0x%lx",
-                    __func__, reloc_idx, rsec->name, rsec->sh.sh_size);
+       if (reloc_idx >= sec_num_entries(rsec)) {
+               WARN("%s: bad reloc_idx %u for %s with %d relocs",
+                    __func__, reloc_idx, rsec->name, sec_num_entries(rsec));
                return NULL;
        }
 
-       reloc = &rsec->reloc_data[reloc_idx];
+       reloc = &rsec->relocs[reloc_idx];
 
        if (memcmp(reloc, &empty, sizeof(empty))) {
                WARN("%s: %s: reloc %d already initialized!",
@@ -841,7 +840,6 @@ static struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
                return NULL;
 
        list_add_tail(&reloc->sym_reloc_entry, &sym->reloc_list);
-       list_add_tail(&reloc->list, &rsec->reloc_list);
        elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
 
        return reloc;
@@ -944,14 +942,13 @@ static int read_relocs(struct elf *elf)
                rsec->base->rsec = rsec;
 
                nr_reloc = 0;
-               rsec->reloc_data = calloc(rsec->sh.sh_size / rsec->sh.sh_entsize,
-                                         sizeof(*reloc));
-               if (!rsec->reloc_data) {
+               rsec->relocs = calloc(sec_num_entries(rsec), sizeof(*reloc));
+               if (!rsec->relocs) {
                        perror("calloc");
                        return -1;
                }
-               for (i = 0; i < rsec->sh.sh_size / rsec->sh.sh_entsize; i++) {
-                       reloc = &rsec->reloc_data[i];
+               for (i = 0; i < sec_num_entries(rsec); i++) {
+                       reloc = &rsec->relocs[i];
 
                        if (read_reloc(rsec, i, reloc))
                                return -1;
@@ -967,7 +964,6 @@ static int read_relocs(struct elf *elf)
                        }
 
                        list_add_tail(&reloc->sym_reloc_entry, &sym->reloc_list);
-                       list_add_tail(&reloc->list, &rsec->reloc_list);
                        elf_hash_add(reloc, &reloc->hash, reloc_hash(reloc));
 
                        nr_reloc++;
@@ -1093,7 +1089,6 @@ struct section *elf_create_section(struct elf *elf, const char *name,
        memset(sec, 0, sizeof(*sec));
 
        INIT_LIST_HEAD(&sec->symbol_list);
-       INIT_LIST_HEAD(&sec->reloc_list);
 
        s = elf_newscn(elf->elf);
        if (!s) {
@@ -1186,9 +1181,8 @@ static struct section *elf_create_rela_section(struct elf *elf,
        rsec->sh.sh_info = sec->idx;
        rsec->sh.sh_flags = SHF_INFO_LINK;
 
-       rsec->reloc_data = calloc(rsec->sh.sh_size / rsec->sh.sh_entsize,
-                                 sizeof(struct reloc));
-       if (!rsec->reloc_data) {
+       rsec->relocs = calloc(sec_num_entries(rsec), sizeof(struct reloc));
+       if (!rsec->relocs) {
                perror("calloc");
                return NULL;
        }

diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index a938cb1..a09da20 100644 (file)
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -33,14 +33,13 @@ struct section {
        GElf_Shdr sh;
        struct rb_root_cached symbol_tree;
        struct list_head symbol_list;
-       struct list_head reloc_list;
        struct section *base, *rsec;
        struct symbol *sym;
        Elf_Data *data;
        char *name;
        int idx;
        bool _changed, text, rodata, noinstr, init, truncate;
-       struct reloc *reloc_data;
+       struct reloc *relocs;
 };
 
 struct symbol {
@@ -68,7 +67,6 @@ struct symbol {
 };
 
 struct reloc {
-       struct list_head list;
        struct hlist_node hash;
        union {
                GElf_Rela rela;
@@ -197,6 +195,11 @@ static inline void mark_sec_changed(struct elf *elf, struct section *sec,
        elf->changed |= changed;
 }
 
+static inline unsigned int sec_num_entries(struct section *sec)
+{
+       return sec->sh.sh_size / sec->sh.sh_entsize;
+}
+
 #define for_each_sec(file, sec)                                                \
        list_for_each_entry(sec, &file->elf->sections, list)
 
@@ -210,10 +213,15 @@ static inline void mark_sec_changed(struct elf *elf, struct section *sec,
                        sec_for_each_sym(__sec, sym)
 
 #define for_each_reloc(rsec, reloc)                                    \
-       list_for_each_entry(reloc, &rsec->reloc_list, list)
+       for (int __i = 0, __fake = 1; __fake; __fake = 0)               \
+               for (reloc = rsec->relocs;                              \
+                    __i < sec_num_entries(rsec);                       \
+                    __i++, reloc++)
 
 #define for_each_reloc_from(rsec, reloc)                               \
-       list_for_each_entry_from(reloc, &rsec->reloc_list, list)
+       for (int __i = reloc->idx;                                      \
+            __i < sec_num_entries(rsec);                               \
+            __i++, reloc++)
 
 #define OFFSET_STRIDE_BITS     4
 #define OFFSET_STRIDE          (1UL << OFFSET_STRIDE_BITS)