make relocation time symbol lookup and dlsym consistent

Using common code path for all symbol lookups fixes three dlsym issues:

- st_shndx of STT_TLS symbols were not checked and thus an undefined
  tls symbol reference could be incorrectly treated as a definition
  (the sysv hash lookup returns undefined symbols, gnu does not, so should
  be rare in practice).

- symbol binding was not checked so a hidden symbol may be returned
  (in principle STB_LOCAL symbols may appear in the dynamic symbol table
  for hidden symbols, but linkers most likely don't produce it).

- mips specific behaviour was not applied (ARCH_SYM_REJECT_UND) so
  undefined symbols may be returned on mips.

always_inline is used to avoid relocation performance regression, the
code generation for find_sym should not be affected.

diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index b9b2e96c89e6ff027bc9fbb0d5efd9acb01be3f5..a124e70449df987b2bf491275a27740a4c2c1051 100644 (file)
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -283,12 +283,16 @@ static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso,
 #define ARCH_SYM_REJECT_UND(s) 0
 #endif
 
-static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
+#if defined(__GNUC__)
+__attribute__((always_inline))
+#endif
+static inline struct symdef find_sym2(struct dso *dso, const char *s, int need_def, int use_deps)
 {
        uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
        size_t ghm = 1ul << gh % (8*sizeof(size_t));
        struct symdef def = {0};
-       for (; dso; dso=dso->syms_next) {
+       struct dso **deps = use_deps ? dso->deps : 0;
+       for (; dso; dso=use_deps ? *deps++ : dso->syms_next) {
                Sym *sym;
                if ((ght = dso->ghashtab)) {
                        sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
@@ -313,6 +317,11 @@ static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
        return def;
 }
 
+static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
+{
+       return find_sym2(dso, s, need_def, 0);
+}
+
 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
 {
        unsigned char *base = dso->base;
@@ -2123,58 +2132,27 @@ static void *addr2dso(size_t a)
 
 static void *do_dlsym(struct dso *p, const char *s, void *ra)
 {
-       size_t i;
-       uint32_t h = 0, gh = 0, *ght;
-       Sym *sym;
-       if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
-               if (p == RTLD_DEFAULT) {
-                       p = head;
-               } else if (p == RTLD_NEXT) {
-                       p = addr2dso((size_t)ra);
-                       if (!p) p=head;
-                       p = p->next;
-               }
-               struct symdef def = find_sym(p, s, 0);
-               if (!def.sym) goto failed;
-               if ((def.sym->st_info&0xf) == STT_TLS)
-                       return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
-               if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
-                       return def.dso->funcdescs + (def.sym - def.dso->syms);
-               return laddr(def.dso, def.sym->st_value);
-       }
-       if (__dl_invalid_handle(p))
+       int use_deps = 0;
+       if (p == head || p == RTLD_DEFAULT) {
+               p = head;
+       } else if (p == RTLD_NEXT) {
+               p = addr2dso((size_t)ra);
+               if (!p) p=head;
+               p = p->next;
+       } else if (__dl_invalid_handle(p)) {
                return 0;
-       if ((ght = p->ghashtab)) {
-               gh = gnu_hash(s);
-               sym = gnu_lookup(gh, ght, p, s);
-       } else {
-               h = sysv_hash(s);
-               sym = sysv_lookup(s, h, p);
-       }
-       if (sym && (sym->st_info&0xf) == STT_TLS)
-               return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
-       if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
-               return p->funcdescs + (sym - p->syms);
-       if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
-               return laddr(p, sym->st_value);
-       for (i=0; p->deps[i]; i++) {
-               if ((ght = p->deps[i]->ghashtab)) {
-                       if (!gh) gh = gnu_hash(s);
-                       sym = gnu_lookup(gh, ght, p->deps[i], s);
-               } else {
-                       if (!h) h = sysv_hash(s);
-                       sym = sysv_lookup(s, h, p->deps[i]);
-               }
-               if (sym && (sym->st_info&0xf) == STT_TLS)
-                       return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
-               if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
-                       return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
-               if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
-                       return laddr(p->deps[i], sym->st_value);
-       }
-failed:
-       error("Symbol not found: %s", s);
-       return 0;
+       } else
+               use_deps = 1;
+       struct symdef def = find_sym2(p, s, 0, use_deps);
+       if (!def.sym) {
+               error("Symbol not found: %s", s);
+               return 0;
+       }
+       if ((def.sym->st_info&0xf) == STT_TLS)
+               return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
+       if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
+               return def.dso->funcdescs + (def.sym - def.dso->syms);
+       return laddr(def.dso, def.sym->st_value);
 }
 
 int dladdr(const void *addr_arg, Dl_info *info)