fix dlsym lookup of function symbols on fdpic

previously these resolved to the code address rather than the address
of the function descriptor.

the conditions for accepting or rejecting symbols are quite
inconsistent between the different points in the dynamic linker code
where such decisions are made. this commit attempts to be at least as
correct as anything already there, but does not improve consistency.
it has been tested to correctly avoid symbols that are merely
references to functions defined in other modules, at least in simple
usage, but at some point all symbol lookup logic should be reviewed
and refactored/unified.

diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index f144aa597f3586ba2dc6bc8bbdba3e6bf159a449..0c3b36ce8d40e6c7fa9688220d9726a4492e212e 100644 (file)
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -1757,6 +1757,8 @@ static void *do_dlsym(struct dso *p, const char *s, void *ra)
                if (!def.sym) goto failed;
                if ((def.sym->st_info&0xf) == STT_TLS)
                        return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
+               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 (invalid_dso_handle(p))
@@ -1770,6 +1772,8 @@ static void *do_dlsym(struct dso *p, const char *s, void *ra)
        }
        if (sym && (sym->st_info&0xf) == STT_TLS)
                return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
+       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);
        if (p->deps) for (i=0; p->deps[i]; i++) {
@@ -1782,6 +1786,8 @@ static void *do_dlsym(struct dso *p, const char *s, void *ra)
                }
                if (sym && (sym->st_info&0xf) == STT_TLS)
                        return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
+               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);
        }