objtool: Fix reloc_hash size

With CONFIG_DEBUG_INFO, DWARF creates a lot of relocations and
reloc_hash is woefully undersized, which can affect performance
significantly.  Fix that.

Link: https://lore.kernel.org/r/38ef60dc8043270bf3b9dfd139ae2a30ca3f75cc.1685464332.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

tools/objtool/elf.c

@@ -328,12 +328,12 @@ static int read_sections(struct elf *elf)
 			}
 		}
 
-		if (sec->sh.sh_flags & SHF_EXECINSTR)
-			elf->text_size += sec->sh.sh_size;
-
 		list_add_tail(&sec->list, &elf->sections);
 		elf_hash_add(section, &sec->hash, sec->idx);
 		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;
 	}
 
 	if (opts.stats) {
@@ -888,19 +888,18 @@ static int read_reloc(struct section *rsec, int i, struct reloc *reloc)
 
 static int read_relocs(struct elf *elf)
 {
-	unsigned long nr_reloc, max_reloc = 0, tot_reloc = 0;
+	unsigned long nr_reloc, max_reloc = 0;
 	struct section *rsec;
 	struct reloc *reloc;
 	unsigned int symndx;
 	struct symbol *sym;
 	int i;
 
-	if (!elf_alloc_hash(reloc, elf->text_size / 16))
+	if (!elf_alloc_hash(reloc, elf->num_relocs))
 		return -1;
 
 	list_for_each_entry(rsec, &elf->sections, list) {
-		if ((rsec->sh.sh_type != SHT_RELA) &&
-		    (rsec->sh.sh_type != SHT_REL))
+		if (!is_reloc_sec(rsec))
 			continue;
 
 		rsec->base = find_section_by_index(elf, rsec->sh.sh_info);
@@ -942,12 +941,11 @@ static int read_relocs(struct elf *elf)
 			nr_reloc++;
 		}
 		max_reloc = max(max_reloc, nr_reloc);
-		tot_reloc += nr_reloc;
 	}
 
 	if (opts.stats) {
 		printf("max_reloc: %lu\n", max_reloc);
-		printf("tot_reloc: %lu\n", tot_reloc);
+		printf("num_relocs: %lu\n", elf->num_relocs);
 		printf("reloc_bits: %d\n", elf->reloc_bits);
 	}
 

tools/objtool/include/objtool/elf.h

@@ -90,8 +90,9 @@ struct elf {
 	int fd;
 	bool changed;
 	char *name;
-	unsigned int text_size, num_files;
+	unsigned int num_files;
 	struct list_head sections;
+	unsigned long num_relocs;
 
 	int symbol_bits;
 	int symbol_name_bits;
@@ -158,6 +159,11 @@ static inline size_t elf_rela_size(struct elf *elf)
 	return elf_addr_size(elf) == 4 ? sizeof(Elf32_Rela) : sizeof(Elf64_Rela);
 }
 
+static inline bool is_reloc_sec(struct section *sec)
+{
+	return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
+}
+
 #define for_each_sec(file, sec)						\
 	list_for_each_entry(sec, &file->elf->sections, list)