elf/symbol: SKip extern symbol

    $ ./src/tests/ulpatch_test -f Elf.for_each_symbol -v | grep sym:printf
    =========================================
    ===
    === ULPatch Testing
    ===
    ===  version: v0.5.7-133-g8b30-dirty
    === ---------------------------
    ===   19/77   Elf.for_each_symbol
    sym:printf@GLIBC_2.2.5 extern:0 nphdrs:0
    sym:printf extern:0 nphdrs:0
    5769us OK
    =========================================
    === Total 1 tested
    ===  Success 1
    ===  Failed 0
    ===  Spend 5ms 5.77ms/per
    =========================================

Signed-off-by: Rong Tao <[email protected]>

src/elf/elf_api.h

@@ -83,9 +83,16 @@ struct symbol {
 	/**
 	 * Store GELF_ST_TYPE(sym->st_info), such as STT_OBJECT/STT_FUNC
 	 * for rbtree compare and search.
+	 *
+	 * FIXME: This field is not useful right now.
 	 */
 	int type;
 
+	/**
+	 * Mark the symbol is extern or not, it's use to resolve symbol.
+	 */
+	bool is_extern;
+
 	GElf_Sym sym;
 
 	/**

src/elf/symbol.c

@@ -342,19 +342,20 @@ const char *elf_mcount_name(struct elf_file *elf)
 int cmp_symbol_name(struct rb_node *n1, unsigned long key)
 {
 	struct symbol *s1 = rb_entry(n1, struct symbol, node);
-	struct symbol *s2 = (struct symbol*)key;
+	struct symbol *s2 = (struct symbol *)key;
 
-/**
- * FIXME: pthread_create()'s symbol type in ulp is STT_NOTYPE
- */
-#if 0
-	if (s1->type < s2->type) {
+	/**
+	 * FIXME: pthread_create()'s symbol type in ulp is STT_NOTYPE, and
+	 * kernel does not distinguish symbol type.
+	 */
+
+	if (s1->is_extern == s2->is_extern)
+		return strcmp(s1->name, s2->name);
+	else if (s1->is_extern > s2->is_extern)
 		return -1;
-	} else if (s1->type > s2->type) {
+	else if (s1->is_extern < s2->is_extern)
 		return 1;
-	} else
-#endif
-		return strcmp(s1->name, s2->name);
+	return 0;
 }
 
 struct symbol *alloc_symbol(const char *name, const GElf_Sym *sym)
@@ -365,6 +366,7 @@ struct symbol *alloc_symbol(const char *name, const GElf_Sym *sym)
 
 	s->name = strdup(name);
 	s->type = GELF_ST_TYPE(sym->st_info);
+	s->is_extern = is_extern_symbol(sym);
 
 	memcpy(&s->sym, sym, sizeof(GElf_Sym));
 
@@ -376,6 +378,7 @@ struct symbol *find_symbol(struct elf_file *elf, const char *name, int type)
 	struct symbol tmp = {
 		.name = (char *)name,
 		.type = type,
+		.is_extern = false,
 	};
 	struct rb_node *node = rb_search_node(&elf->elf_file_symbols,
 					      cmp_symbol_name,
@@ -459,6 +462,16 @@ void rb_free_symbol(struct rb_node *node)
 
 int fprint_symbol(FILE *fp, struct symbol *s, int firstline)
 {
+	int i;
+
+	fprintf(fp, "sym:%s extern:%d nphdrs:%d\n", s->name, s->is_extern,
+		s->nphdrs);
+
+	if (s->nphdrs > 0) {
+		for (i = 0; i < s->nphdrs; i++)
+			print_phdr(stdout, &s->phdrs[i], i == 0);
+	}
+
 	return fprint_sym(fp, &s->sym, s->name, NULL, firstline);
 }
 

src/tests/elf/symbol.c

@@ -24,15 +24,8 @@ static const struct symbol_t sym_funcs[] = {
 static void print_elf_symbol(struct elf_file *elf, struct symbol *sym,
 			     void *arg)
 {
-	int i;
 	static bool firstline = true;
-
-	fprint_sym(stdout, &sym->sym, sym->name, NULL, firstline);
-	if (sym->nphdrs > 0) {
-		for (i = 0; i < sym->nphdrs; i++)
-			print_phdr(stdout, &sym->phdrs[i], i == 0);
-	}
-
+	fprint_symbol(stdout, sym, firstline);
 	firstline = false;
 }
 

src/utils/task.c

@@ -826,6 +826,7 @@ struct symbol *task_vma_find_symbol(struct task_struct *task, const char *name,
 	struct symbol tmp = {
 		.name = (char *)name,
 		.type = type,
+		.is_extern = false,
 	};
 
 	ldebug("try find symbol %s\n", name);