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Fix some multi-file corner cases with asm 

for this we have to create also asm symbols as VT_STATIC initially
except if there's an indication that it should be global (.globl
or undefined at end of unit).  For this to work we need to
be able to globalize symbols after they were local and enter them
into the ELF hash tables, and also adjust the symbols that were
potentially already used in relocs when they were still local.

The easiest is to do a proper symbol resolution step also in multi-file
mode, for regular symbols (the non-dynamic ones, i.e. not from shared
libs).
master
Michael Matz 2017-12-10 06:18:27 +01:00
parent 3ae1a2af1c
commit 8490c54dbd
5 changed files with 73 additions and 44 deletions
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4
tcc.h
View File

@ -911,7 +911,6 @@ struct filespec {
/* symbol was created by tccasm.c first */
#define VT_ASM (VT_VOID | VT_UNSIGNED)
#define VT_ASM_GLOBAL VT_DEFSIGN
#define IS_ASM_SYM(sym) (((sym)->type.t & (VT_BTYPE | VT_ASM)) == VT_ASM)
/* token values */
@ -1426,11 +1425,10 @@ ST_FUNC void put_stabs_r(const char *str, int type, int other, int desc, unsigne
ST_FUNC void put_stabn(int type, int other, int desc, int value);
ST_FUNC void put_stabd(int type, int other, int desc);
ST_FUNC void relocate_common_syms(void);
ST_FUNC void resolve_regular_syms(void);
ST_FUNC void relocate_syms(TCCState *s1, Section *symtab, int do_resolve);
ST_FUNC void relocate_section(TCCState *s1, Section *s);
ST_FUNC void tcc_add_linker_symbols(TCCState *s1);
ST_FUNC int tcc_object_type(int fd, ElfW(Ehdr) *h);
ST_FUNC int tcc_load_object_file(TCCState *s1, int fd, unsigned long file_offset);
ST_FUNC int tcc_load_archive(TCCState *s1, int fd);

21
tccasm.c
View File

@ -42,13 +42,12 @@ static Sym *asm_label_find(int v)
return sym;
}
static Sym *asm_label_push(int v, int t)
static Sym *asm_label_push(int v)
{
Sym *sym = global_identifier_push(v, t, 0);
/* We always add VT_EXTERN, for sym definition that's tentative
(for .set, removed for real defs), for mere references it's correct
as is. */
sym->type.t |= VT_ASM | VT_EXTERN;
Sym *sym = global_identifier_push(v, VT_ASM | VT_EXTERN | VT_STATIC, 0);
sym->r = VT_CONST | VT_SYM;
return sym;
}
@ -67,7 +66,7 @@ ST_FUNC Sym* get_asm_sym(int name, Sym *csym)
{
Sym *sym = asm_label_find(name);
if (!sym) {
sym = asm_label_push(name, 0);
sym = asm_label_push(name);
if (csym)
sym->c = csym->c;
}
@ -102,7 +101,7 @@ static void asm_expr_unary(TCCState *s1, ExprValue *pe)
/* forward */
if (!sym || (sym->c && elfsym(sym)->st_shndx != SHN_UNDEF)) {
/* if the last label is defined, then define a new one */
sym = asm_label_push(label, VT_STATIC);
sym = asm_label_push(label);
}
}
pe->v = 0;
@ -381,7 +380,7 @@ static Sym* asm_new_label1(TCCState *s1, int label, int is_local,
}
} else {
new_label:
sym = asm_label_push(label, is_local == 1 ? VT_STATIC : 0);
sym = asm_label_push(label);
}
if (!sym->c)
put_extern_sym2(sym, NULL, 0, 0, 0);
@ -392,11 +391,6 @@ static Sym* asm_new_label1(TCCState *s1, int label, int is_local,
if (is_local != 2)
sym->type.t &= ~VT_EXTERN;
if (IS_ASM_SYM(sym) && !(sym->type.t & VT_ASM_GLOBAL)) {
sym->type.t |= VT_STATIC;
update_storage(sym);
}
return sym;
}
@ -679,11 +673,8 @@ static void asm_parse_directive(TCCState *s1, int global)
Sym *sym;
next();
sym = get_asm_sym(tok, NULL);
if (tok1 != TOK_ASMDIR_hidden) {
if (tok1 != TOK_ASMDIR_hidden)
sym->type.t &= ~VT_STATIC;
if (IS_ASM_SYM(sym))
sym->type.t |= VT_ASM_GLOBAL;
}
if (tok1 == TOK_ASMDIR_weak)
sym->a.weak = 1;
else if (tok1 == TOK_ASMDIR_hidden)

86
tccelf.c
View File

@ -299,6 +299,9 @@ static void rebuild_hash(Section *s, unsigned int nb_buckets)
strtab = s->link->data;
nb_syms = s->data_offset / sizeof(ElfW(Sym));
if (!nb_buckets)
nb_buckets = ((int*)s->hash->data)[0];
s->hash->data_offset = 0;
ptr = section_ptr_add(s->hash, (2 + nb_buckets + nb_syms) * sizeof(int));
ptr[0] = nb_buckets;
@ -370,9 +373,7 @@ ST_FUNC int put_elf_sym(Section *s, addr_t value, unsigned long size,
return sym_index;
}
/* find global ELF symbol 'name' and return its index. Return 0 if not
found. */
ST_FUNC int find_elf_sym(Section *s, const char *name)
static int find_elf_sym_1(Section *s, const char *name, int onlydef)
{
ElfW(Sym) *sym;
Section *hs;
@ -388,13 +389,21 @@ ST_FUNC int find_elf_sym(Section *s, const char *name)
while (sym_index != 0) {
sym = &((ElfW(Sym) *)s->data)[sym_index];
name1 = (char *) s->link->data + sym->st_name;
if (!strcmp(name, name1) && ELFW(ST_BIND)(sym->st_info) != STB_LOCAL)
if (!strcmp(name, name1) && ELFW(ST_BIND)(sym->st_info) != STB_LOCAL
&& (!onlydef || sym->st_shndx != SHN_UNDEF))
return sym_index;
sym_index = ((int *)hs->data)[2 + nbuckets + sym_index];
}
return 0;
}
/* find global ELF symbol 'name' and return its index. Return 0 if not
found. */
ST_FUNC int find_elf_sym(Section *s, const char *name)
{
return find_elf_sym_1(s, name, 0);
}
/* return elf symbol value, signal error if 'err' is nonzero */
ST_FUNC addr_t get_elf_sym_addr(TCCState *s, const char *name, int err)
{
@ -716,21 +725,6 @@ static void sort_syms(TCCState *s1, Section *s)
tcc_free(old_to_new_syms);
}
/* relocate common symbols in the .bss section */
ST_FUNC void relocate_common_syms(void)
{
ElfW(Sym) *sym;
for_each_elem(symtab_section, 1, sym, ElfW(Sym)) {
if (sym->st_shndx == SHN_COMMON) {
/* symbol alignment is in st_value for SHN_COMMONs */
sym->st_value = section_add(bss_section, sym->st_size,
sym->st_value);
sym->st_shndx = bss_section->sh_num;
}
}
}
/* relocate symbol table, resolve undefined symbols if do_resolve is
true and output error if undefined symbol. */
ST_FUNC void relocate_syms(TCCState *s1, Section *symtab, int do_resolve)
@ -1167,7 +1161,7 @@ ST_FUNC void tcc_add_runtime(TCCState *s1)
/* add various standard linker symbols (must be done after the
sections are filled (for example after allocating common
symbols)) */
ST_FUNC void tcc_add_linker_symbols(TCCState *s1)
static void tcc_add_linker_symbols(TCCState *s1)
{
char buf[1024];
int i;
@ -1226,6 +1220,47 @@ ST_FUNC void tcc_add_linker_symbols(TCCState *s1)
}
}
/* Do final regular symbol preparation (for those coming from .c/.o/.s files,
not from shared libs) */
ST_FUNC void resolve_regular_syms(void)
{
int rebuild = 0;
ElfW(Sym) *sym;
/* Allocate common symbols in BSS. */
for_each_elem(symtab_section, 1, sym, ElfW(Sym)) {
if (sym->st_shndx == SHN_COMMON) {
/* symbol alignment is in st_value for SHN_COMMONs */
sym->st_value = section_add(bss_section, sym->st_size,
sym->st_value);
sym->st_shndx = bss_section->sh_num;
}
}
/* Now assign linker provided symbols their value. */
tcc_add_linker_symbols(tcc_state);
/* And finally resolve still UNDEF symbols (for multi-file mode),
and globalize those that are still UNDEF. */
rebuild_hash(symtab_section, 0);
for_each_elem(symtab_section, 1, sym, ElfW(Sym)) {
if (sym->st_shndx == SHN_UNDEF) {
const char *name = (char *) symtab_section->link->data + sym->st_name;
int symndx = find_elf_sym_1(symtab_section, name, 1);
if (symndx) {
*sym = ((ElfSym *)symtab_section->data)[symndx];
rebuild = 1;
} else if (ELFW(ST_BIND)(sym->st_info) == STB_LOCAL) {
sym->st_info
= ELFW(ST_INFO)(STB_GLOBAL, ELFW(ST_TYPE)(sym->st_info));
rebuild = 1;
}
}
}
if (rebuild)
rebuild_hash(symtab_section, 0);
}
static void tcc_output_binary(TCCState *s1, FILE *f,
const int *sec_order)
{
@ -2016,8 +2051,7 @@ static int elf_output_file(TCCState *s1, const char *filename)
if (file_type != TCC_OUTPUT_OBJ) {
/* if linking, also link in runtime libraries (libc, libgcc, etc.) */
tcc_add_runtime(s1);
relocate_common_syms();
tcc_add_linker_symbols(s1);
resolve_regular_syms();
if (!s1->static_link) {
if (file_type == TCC_OUTPUT_EXE) {
@ -2058,6 +2092,14 @@ static int elf_output_file(TCCState *s1, const char *filename)
}
}
build_got_entries(s1);
} else {
for_each_elem(symtab_section, 1, sym, ElfW(Sym)) {
if (sym->st_shndx == SHN_UNDEF
&& ELFW(ST_BIND)(sym->st_info) == STB_LOCAL) {
sym->st_info
= ELFW(ST_INFO)(STB_GLOBAL, ELFW(ST_TYPE)(sym->st_info));
}
}
}
/* we add a section for symbols */

3
tccpe.c
View File

@ -1970,8 +1970,7 @@ ST_FUNC int pe_output_file(TCCState *s1, const char *filename)
tcc_add_bcheck(s1);
pe_add_runtime(s1, &pe);
relocate_common_syms(); /* assign bss addresses */
tcc_add_linker_symbols(s1);
resolve_regular_syms();
pe_set_options(s1, &pe);
ret = pe_check_symbols(&pe);

3
tccrun.c
View File

@ -188,8 +188,7 @@ static int tcc_relocate_ex(TCCState *s1, void *ptr, addr_t ptr_diff)
pe_output_file(s1, NULL);
#else
tcc_add_runtime(s1);
relocate_common_syms();
tcc_add_linker_symbols(s1);
resolve_regular_syms();
build_got_entries(s1);
#endif
if (s1->nb_errors)