svn commit: r217223 - head/libexec/rtld-elf
Konstantin Belousov
kib at FreeBSD.org
Mon Jan 10 16:09:36 UTC 2011
Author: kib
Date: Mon Jan 10 16:09:35 2011
New Revision: 217223
URL: http://svn.freebsd.org/changeset/base/217223
Log:
get_program_var_addr() must prefer the strong symbol to the weak
one. Search global objects, together with main object and
dependencies, for the requested symbol.
Move the common code from symlook_default() into new helper
symlook_global(), and use it both in symlook_global() and
get_program_var_addr().
Supply lock state to get_program_var_addr().
Reviewed by: kan
Tested by: Mykola Dzham <i levsha me>
Modified:
head/libexec/rtld-elf/rtld.c
Modified: head/libexec/rtld-elf/rtld.c
==============================================================================
--- head/libexec/rtld-elf/rtld.c Mon Jan 10 06:46:18 2011 (r217222)
+++ head/libexec/rtld-elf/rtld.c Mon Jan 10 16:09:35 2011 (r217223)
@@ -103,7 +103,7 @@ static void unload_filtees(Obj_Entry *);
static int load_needed_objects(Obj_Entry *, int);
static int load_preload_objects(void);
static Obj_Entry *load_object(const char *, const Obj_Entry *, int);
-static void map_stacks_exec(void);
+static void map_stacks_exec(RtldLockState *);
static Obj_Entry *obj_from_addr(const void *);
static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
static void objlist_call_init(Objlist *, RtldLockState *);
@@ -119,9 +119,10 @@ static int rtld_dirname(const char *, ch
static int rtld_dirname_abs(const char *, char *);
static void rtld_exit(void);
static char *search_library_path(const char *, const char *);
-static const void **get_program_var_addr(const char *);
+static const void **get_program_var_addr(const char *, RtldLockState *);
static void set_program_var(const char *, const void *);
static int symlook_default(SymLook *, const Obj_Entry *refobj);
+static int symlook_global(SymLook *, DoneList *);
static void symlook_init_from_req(SymLook *, const SymLook *);
static int symlook_list(SymLook *, const Objlist *, DoneList *);
static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
@@ -528,7 +529,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_
r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
- map_stacks_exec();
+ map_stacks_exec(NULL);
wlock_acquire(rtld_bind_lock, &lockstate);
objlist_call_init(&initlist, &lockstate);
@@ -2129,12 +2130,18 @@ dllockinit(void *context,
void *
dlopen(const char *name, int mode)
{
+ RtldLockState lockstate;
int lo_flags;
LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
- if (ld_tracing != NULL)
- environ = (char **)*get_program_var_addr("environ");
+ if (ld_tracing != NULL) {
+ rlock_acquire(rtld_bind_lock, &lockstate);
+ if (setjmp(lockstate.env) != 0)
+ lock_upgrade(rtld_bind_lock, &lockstate);
+ environ = (char **)*get_program_var_addr("environ", &lockstate);
+ lock_release(rtld_bind_lock, &lockstate);
+ }
lo_flags = RTLD_LO_DLOPEN;
if (mode & RTLD_NODELETE)
lo_flags |= RTLD_LO_NODELETE;
@@ -2220,7 +2227,7 @@ dlopen_object(const char *name, Obj_Entr
name);
GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
- map_stacks_exec();
+ map_stacks_exec(&lockstate);
/* Call the init functions. */
objlist_call_init(&initlist, &lockstate);
@@ -2779,21 +2786,20 @@ r_debug_state(struct r_debug* rd, struct
/*
* Get address of the pointer variable in the main program.
+ * Prefer non-weak symbol over the weak one.
*/
static const void **
-get_program_var_addr(const char *name)
+get_program_var_addr(const char *name, RtldLockState *lockstate)
{
- const Obj_Entry *obj;
SymLook req;
+ DoneList donelist;
symlook_init(&req, name);
- for (obj = obj_main; obj != NULL; obj = obj->next) {
- if (symlook_obj(&req, obj) == 0) {
- return ((const void **)(req.defobj_out->relocbase +
- req.sym_out->st_value));
- }
- }
- return (NULL);
+ req.lockstate = lockstate;
+ donelist_init(&donelist);
+ if (symlook_global(&req, &donelist) != 0)
+ return (NULL);
+ return ((const void **)(req.defobj_out->relocbase + req.sym_out->st_value));
}
/*
@@ -2806,13 +2812,55 @@ set_program_var(const char *name, const
{
const void **addr;
- if ((addr = get_program_var_addr(name)) != NULL) {
+ if ((addr = get_program_var_addr(name, NULL)) != NULL) {
dbg("\"%s\": *%p <-- %p", name, addr, value);
*addr = value;
}
}
/*
+ * Search the global objects, including dependencies and main object,
+ * for the given symbol.
+ */
+static int
+symlook_global(SymLook *req, DoneList *donelist)
+{
+ SymLook req1;
+ const Objlist_Entry *elm;
+ int res;
+
+ symlook_init_from_req(&req1, req);
+
+ /* Search all objects loaded at program start up. */
+ if (req->defobj_out == NULL ||
+ ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
+ res = symlook_list(&req1, &list_main, donelist);
+ if (res == 0 && (req->defobj_out == NULL ||
+ ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
+ req->sym_out = req1.sym_out;
+ req->defobj_out = req1.defobj_out;
+ assert(req->defobj_out != NULL);
+ }
+ }
+
+ /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
+ STAILQ_FOREACH(elm, &list_global, link) {
+ if (req->defobj_out != NULL &&
+ ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
+ break;
+ res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
+ if (res == 0 && (req->defobj_out == NULL ||
+ ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
+ req->sym_out = req1.sym_out;
+ req->defobj_out = req1.defobj_out;
+ assert(req->defobj_out != NULL);
+ }
+ }
+
+ return (req->sym_out != NULL ? 0 : ESRCH);
+}
+
+/*
* Given a symbol name in a referencing object, find the corresponding
* definition of the symbol. Returns a pointer to the symbol, or NULL if
* no definition was found. Returns a pointer to the Obj_Entry of the
@@ -2822,13 +2870,10 @@ static int
symlook_default(SymLook *req, const Obj_Entry *refobj)
{
DoneList donelist;
- const Elf_Sym *def;
- const Obj_Entry *defobj;
const Objlist_Entry *elm;
SymLook req1;
int res;
- def = NULL;
- defobj = NULL;
+
donelist_init(&donelist);
symlook_init_from_req(&req1, req);
@@ -2836,46 +2881,25 @@ symlook_default(SymLook *req, const Obj_
if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
res = symlook_obj(&req1, refobj);
if (res == 0) {
- def = req1.sym_out;
- defobj = req1.defobj_out;
- assert(defobj != NULL);
+ req->sym_out = req1.sym_out;
+ req->defobj_out = req1.defobj_out;
+ assert(req->defobj_out != NULL);
}
}
- /* Search all objects loaded at program start up. */
- if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
- res = symlook_list(&req1, &list_main, &donelist);
- if (res == 0 &&
- (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
- def = req1.sym_out;
- defobj = req1.defobj_out;
- assert(defobj != NULL);
- }
- }
-
- /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
- STAILQ_FOREACH(elm, &list_global, link) {
- if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
- break;
- res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
- if (res == 0 &&
- (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
- def = req1.sym_out;
- defobj = req1.defobj_out;
- assert(defobj != NULL);
- }
- }
+ symlook_global(req, &donelist);
/* Search all dlopened DAGs containing the referencing object. */
STAILQ_FOREACH(elm, &refobj->dldags, link) {
- if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
+ if (req->sym_out != NULL &&
+ ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
break;
res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
- if (res == 0 &&
- (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
- def = req1.sym_out;
- defobj = req1.defobj_out;
- assert(defobj != NULL);
+ if (res == 0 && (req->sym_out == NULL ||
+ ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
+ req->sym_out = req1.sym_out;
+ req->defobj_out = req1.defobj_out;
+ assert(req->defobj_out != NULL);
}
}
@@ -2884,22 +2908,17 @@ symlook_default(SymLook *req, const Obj_
* symbol from there. This is how the application links to
* dynamic linker services such as dlopen.
*/
- if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
+ if (req->sym_out == NULL ||
+ ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
res = symlook_obj(&req1, &obj_rtld);
if (res == 0) {
- def = req1.sym_out;
- defobj = req1.defobj_out;
- assert(defobj != NULL);
+ req->sym_out = req1.sym_out;
+ req->defobj_out = req1.defobj_out;
+ assert(req->defobj_out != NULL);
}
}
- if (def != NULL) {
- assert(defobj != NULL);
- req->defobj_out = defobj;
- req->sym_out = def;
- return (0);
- }
- return (ESRCH);
+ return (req->sym_out != NULL ? 0 : ESRCH);
}
static int
@@ -3900,14 +3919,14 @@ _rtld_get_stack_prot(void)
}
static void
-map_stacks_exec(void)
+map_stacks_exec(RtldLockState *lockstate)
{
void (*thr_map_stacks_exec)(void);
if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
return;
thr_map_stacks_exec = (void (*)(void))(uintptr_t)
- get_program_var_addr("__pthread_map_stacks_exec");
+ get_program_var_addr("__pthread_map_stacks_exec", lockstate);
if (thr_map_stacks_exec != NULL) {
stack_prot |= PROT_EXEC;
thr_map_stacks_exec();
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