#include <ctype.h>
#include <dlfcn.h>
#include <semaphore.h>
+#include <sys/membarrier.h>
#include "pthread_impl.h"
#include "libc.h"
#include "dynlink.h"
#define MAXP2(a,b) (-(-(a)&-(b)))
#define ALIGN(x,y) ((x)+(y)-1 & -(y))
+#define container_of(p,t,m) ((t*)((char *)(p)-offsetof(t,m)))
+
struct debug {
int ver;
void *head;
char relocated;
char constructed;
char kernel_mapped;
+ char mark;
+ char bfs_built;
+ char runtime_loaded;
struct dso **deps, *needed_by;
+ size_t ndeps_direct;
+ size_t next_dep;
+ int ctor_visitor;
char *rpath_orig, *rpath;
struct tls_module tls;
size_t tls_id;
static int ldd_mode;
static int ldso_fail;
static int noload;
+static int shutting_down;
static jmp_buf *rtld_fail;
static pthread_rwlock_t lock;
static struct debug debug;
static struct tls_module *tls_tail;
static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
static size_t static_tls_cnt;
-static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
+static pthread_mutex_t init_fini_lock;
+static pthread_cond_t ctor_cond;
+static struct dso *builtin_deps[2];
+static struct dso **main_ctor_queue;
static struct fdpic_loadmap *app_loadmap;
static struct fdpic_dummy_loadmap app_dummy_loadmap;
-static struct dso *const nodeps_dummy;
struct debug *_dl_debug_addr = &debug;
p->ino = st.st_ino;
p->needed_by = needed_by;
p->name = p->buf;
+ p->runtime_loaded = runtime;
strcpy(p->name, pathname);
/* Add a shortname only if name arg was not an explicit pathname. */
if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
return p;
}
+static void load_direct_deps(struct dso *p)
+{
+ size_t i, cnt=0;
+
+ if (p->deps) return;
+ /* For head, all preloads are direct pseudo-dependencies.
+ * Count and include them now to avoid realloc later. */
+ if (p==head) for (struct dso *q=p->next; q; q=q->next)
+ cnt++;
+ for (i=0; p->dynv[i]; i+=2)
+ if (p->dynv[i] == DT_NEEDED) cnt++;
+ /* Use builtin buffer for apps with no external deps, to
+ * preserve property of no runtime failure paths. */
+ p->deps = (p==head && cnt<2) ? builtin_deps :
+ calloc(cnt+1, sizeof *p->deps);
+ if (!p->deps) {
+ error("Error loading dependencies for %s", p->name);
+ if (runtime) longjmp(*rtld_fail, 1);
+ }
+ cnt=0;
+ if (p==head) for (struct dso *q=p->next; q; q=q->next)
+ p->deps[cnt++] = q;
+ for (i=0; p->dynv[i]; i+=2) {
+ if (p->dynv[i] != DT_NEEDED) continue;
+ struct dso *dep = load_library(p->strings + p->dynv[i+1], p);
+ if (!dep) {
+ error("Error loading shared library %s: %m (needed by %s)",
+ p->strings + p->dynv[i+1], p->name);
+ if (runtime) longjmp(*rtld_fail, 1);
+ continue;
+ }
+ p->deps[cnt++] = dep;
+ }
+ p->deps[cnt] = 0;
+ p->ndeps_direct = cnt;
+}
+
static void load_deps(struct dso *p)
{
- size_t i, ndeps=0;
- struct dso ***deps = &p->deps, **tmp, *dep;
- for (; p; p=p->next) {
- for (i=0; p->dynv[i]; i+=2) {
- if (p->dynv[i] != DT_NEEDED) continue;
- dep = load_library(p->strings + p->dynv[i+1], p);
- if (!dep) {
- error("Error loading shared library %s: %m (needed by %s)",
- p->strings + p->dynv[i+1], p->name);
- if (runtime) longjmp(*rtld_fail, 1);
- continue;
- }
- if (runtime) {
- tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
- if (!tmp) longjmp(*rtld_fail, 1);
- tmp[ndeps++] = dep;
- tmp[ndeps] = 0;
- *deps = tmp;
- }
+ if (p->deps) return;
+ for (; p; p=p->next)
+ load_direct_deps(p);
+}
+
+static void extend_bfs_deps(struct dso *p)
+{
+ size_t i, j, cnt, ndeps_all;
+ struct dso **tmp;
+
+ /* Can't use realloc if the original p->deps was allocated at
+ * program entry and malloc has been replaced, or if it's
+ * the builtin non-allocated trivial main program deps array. */
+ int no_realloc = (__malloc_replaced && !p->runtime_loaded)
+ || p->deps == builtin_deps;
+
+ if (p->bfs_built) return;
+ ndeps_all = p->ndeps_direct;
+
+ /* Mark existing (direct) deps so they won't be duplicated. */
+ for (i=0; p->deps[i]; i++)
+ p->deps[i]->mark = 1;
+
+ /* For each dependency already in the list, copy its list of direct
+ * dependencies to the list, excluding any items already in the
+ * list. Note that the list this loop iterates over will grow during
+ * the loop, but since duplicates are excluded, growth is bounded. */
+ for (i=0; p->deps[i]; i++) {
+ struct dso *dep = p->deps[i];
+ for (j=cnt=0; j<dep->ndeps_direct; j++)
+ if (!dep->deps[j]->mark) cnt++;
+ tmp = no_realloc ?
+ malloc(sizeof(*tmp) * (ndeps_all+cnt+1)) :
+ realloc(p->deps, sizeof(*tmp) * (ndeps_all+cnt+1));
+ if (!tmp) {
+ error("Error recording dependencies for %s", p->name);
+ if (runtime) longjmp(*rtld_fail, 1);
+ continue;
+ }
+ if (no_realloc) {
+ memcpy(tmp, p->deps, sizeof(*tmp) * (ndeps_all+1));
+ no_realloc = 0;
}
+ p->deps = tmp;
+ for (j=0; j<dep->ndeps_direct; j++) {
+ if (dep->deps[j]->mark) continue;
+ dep->deps[j]->mark = 1;
+ p->deps[ndeps_all++] = dep->deps[j];
+ }
+ p->deps[ndeps_all] = 0;
}
- if (!*deps) *deps = (struct dso **)&nodeps_dummy;
+ p->bfs_built = 1;
+ for (p=head; p; p=p->next)
+ p->mark = 0;
}
static void load_preload(char *s)
{
struct dso *p;
size_t dyn[DYN_CNT];
+ int self = __pthread_self()->tid;
+
+ /* Take both locks before setting shutting_down, so that
+ * either lock is sufficient to read its value. The lock
+ * order matches that in dlopen to avoid deadlock. */
+ pthread_rwlock_wrlock(&lock);
+ pthread_mutex_lock(&init_fini_lock);
+ shutting_down = 1;
+ pthread_rwlock_unlock(&lock);
for (p=fini_head; p; p=p->fini_next) {
+ while (p->ctor_visitor && p->ctor_visitor!=self)
+ pthread_cond_wait(&ctor_cond, &init_fini_lock);
if (!p->constructed) continue;
decode_vec(p->dynv, dyn, DYN_CNT);
if (dyn[0] & (1<<DT_FINI_ARRAY)) {
}
}
-static void do_init_fini(struct dso *p)
+static struct dso **queue_ctors(struct dso *dso)
{
- size_t dyn[DYN_CNT];
- int need_locking = libc.threads_minus_1;
- /* Allow recursive calls that arise when a library calls
- * dlopen from one of its constructors, but block any
- * other threads until all ctors have finished. */
- if (need_locking) pthread_mutex_lock(&init_fini_lock);
- for (; p; p=p->prev) {
+ size_t cnt, qpos, spos, i;
+ struct dso *p, **queue, **stack;
+
+ if (ldd_mode) return 0;
+
+ /* Bound on queue size is the total number of indirect deps.
+ * If a bfs deps list was built, we can use it. Otherwise,
+ * bound by the total number of DSOs, which is always safe and
+ * is reasonable we use it (for main app at startup). */
+ if (dso->bfs_built) {
+ for (cnt=0; dso->deps[cnt]; cnt++)
+ dso->deps[cnt]->mark = 0;
+ cnt++; /* self, not included in deps */
+ } else {
+ for (cnt=0, p=head; p; cnt++, p=p->next)
+ p->mark = 0;
+ }
+ cnt++; /* termination slot */
+ stack = queue = calloc(cnt, sizeof *queue);
+
+ if (!queue) {
+ error("Error allocating constructor queue: %m\n");
+ if (runtime) longjmp(*rtld_fail, 1);
+ return 0;
+ }
+
+ /* Opposite ends of the allocated buffer serve as an output queue
+ * and a working stack. Setup initial stack with just the argument
+ * dso and initial queue empty... */
+ qpos = 0;
+ spos = cnt;
+ stack[--spos] = dso;
+ dso->next_dep = 0;
+ dso->mark = 1;
+
+ /* Then perform pseudo-DFS sort, but ignoring circular deps. */
+ while (spos<cnt) {
+ p = stack[spos++];
+ while (p->next_dep < p->ndeps_direct) {
+ if (p->deps[p->next_dep]->mark) {
+ p->next_dep++;
+ } else {
+ stack[--spos] = p;
+ p = p->deps[p->next_dep];
+ p->next_dep = 0;
+ p->mark = 1;
+ }
+ }
+ queue[qpos++] = p;
+ }
+ queue[qpos] = 0;
+ for (i=0; i<qpos; i++) queue[i]->mark = 0;
+
+ return queue;
+}
+
+static void do_init_fini(struct dso **queue)
+{
+ struct dso *p;
+ size_t dyn[DYN_CNT], i;
+ int self = __pthread_self()->tid;
+
+ pthread_mutex_lock(&init_fini_lock);
+ for (i=0; (p=queue[i]); i++) {
+ while ((p->ctor_visitor && p->ctor_visitor!=self) || shutting_down)
+ pthread_cond_wait(&ctor_cond, &init_fini_lock);
+ if (p->ctor_visitor || p->constructed)
+ continue;
if (p->constructed) continue;
- p->constructed = 1;
+ p->ctor_visitor = self;
+
decode_vec(p->dynv, dyn, DYN_CNT);
if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
p->fini_next = fini_head;
fini_head = p;
}
+
+ pthread_mutex_unlock(&init_fini_lock);
+
#ifndef NO_LEGACY_INITFINI
if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
fpaddr(p, dyn[DT_INIT])();
size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
while (n--) ((void (*)(void))*fn++)();
}
- if (!need_locking && libc.threads_minus_1) {
- need_locking = 1;
- pthread_mutex_lock(&init_fini_lock);
- }
+
+ pthread_mutex_lock(&init_fini_lock);
+ p->ctor_visitor = 0;
+ p->constructed = 1;
+ pthread_cond_broadcast(&ctor_cond);
}
- if (need_locking) pthread_mutex_unlock(&init_fini_lock);
+ pthread_mutex_unlock(&init_fini_lock);
}
void __libc_start_init(void)
{
- do_init_fini(tail);
+ do_init_fini(main_ctor_queue);
+ if (!__malloc_replaced) free(main_ctor_queue);
+ main_ctor_queue = 0;
}
static void dl_debug_state(void)
tls_align);
}
-void __dl_prepare_for_threads(void)
-{
- /* MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED */
- __syscall(SYS_membarrier, 1<<4, 0);
-}
-
-static sem_t barrier_sem;
-static void bcast_barrier(int s)
-{
- sem_post(&barrier_sem);
-}
-
static void install_new_tls(void)
{
sigset_t set;
pthread_t self = __pthread_self(), td;
- uintptr_t (*newdtv)[tls_cnt+1] = (void *)tail->new_dtv;
+ struct dso *dtv_provider = container_of(tls_tail, struct dso, tls);
+ uintptr_t (*newdtv)[tls_cnt+1] = (void *)dtv_provider->new_dtv;
struct dso *p;
size_t i, j;
size_t old_cnt = self->dtv[0];
}
/* Install new dtls into the enlarged, uninstalled dtv copies. */
for (p=head; ; p=p->next) {
- if (!p->tls_id || self->dtv[p->tls_id]) continue;
+ if (p->tls_id <= old_cnt) continue;
unsigned char *mem = p->new_tls;
for (j=0; j<i; j++) {
unsigned char *new = mem;
}
/* Broadcast barrier to ensure contents of new dtv is visible
- * if the new dtv pointer is. Use SYS_membarrier if it works,
- * otherwise emulate with a signal. */
-
- /* MEMBARRIER_CMD_PRIVATE_EXPEDITED */
- if (__syscall(SYS_membarrier, 1<<3, 0)) {
- sem_init(&barrier_sem, 0, 0);
- struct sigaction sa = {
- .sa_flags = SA_RESTART,
- .sa_handler = bcast_barrier
- };
- memset(&sa.sa_mask, -1, sizeof sa.sa_mask);
- __libc_sigaction(SIGSYNCCALL, &sa, 0);
- for (td=self->next; td!=self; td=td->next)
- if (j) __syscall(SYS_tkill, td->tid, SIGSYNCCALL);
- for (td=self->next; td!=self; td=td->next)
- sem_wait(&barrier_sem);
- sa.sa_handler = SIG_IGN;
- __libc_sigaction(SIGSYNCCALL, &sa, 0);
- sem_destroy(&barrier_sem);
- }
+ * if the new dtv pointer is. The __membarrier function has a
+ * fallback emulation using signals for kernels that lack the
+ * feature at the syscall level. */
+
+ __membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0);
/* Install new dtv for each thread. */
for (j=0, td=self; !j || td!=self; j++, td=td->next) {
}
}
+ /* This must be done before final relocations, since it calls
+ * malloc, which may be provided by the application. Calling any
+ * application code prior to the jump to its entry point is not
+ * valid in our model and does not work with FDPIC, where there
+ * are additional relocation-like fixups that only the entry point
+ * code can see to perform. */
+ main_ctor_queue = queue_ctors(&app);
+
/* The main program must be relocated LAST since it may contin
* copy relocations which depend on libraries' relocations. */
reloc_all(app.next);
size_t i;
int cs;
jmp_buf jb;
+ struct dso **volatile ctor_queue = 0;
if (!file) return head;
__inhibit_ptc();
p = 0;
+ if (shutting_down) {
+ error("Cannot dlopen while program is exiting.");
+ goto end;
+ }
orig_tls_tail = tls_tail;
orig_tls_cnt = tls_cnt;
orig_tls_offset = tls_offset;
free(p->funcdescs);
if (p->rpath != p->rpath_orig)
free(p->rpath);
- if (p->deps != &nodeps_dummy)
- free(p->deps);
+ free(p->deps);
unmap_library(p);
free(p);
+ free(ctor_queue);
}
if (!orig_tls_tail) libc.tls_head = 0;
tls_tail = orig_tls_tail;
}
/* First load handling */
- int first_load = !p->deps;
- if (first_load) {
- load_deps(p);
- if (!p->relocated && (mode & RTLD_LAZY)) {
- prepare_lazy(p);
- for (i=0; p->deps[i]; i++)
- if (!p->deps[i]->relocated)
- prepare_lazy(p->deps[i]);
- }
+ load_deps(p);
+ extend_bfs_deps(p);
+ pthread_mutex_lock(&init_fini_lock);
+ if (!p->constructed) ctor_queue = queue_ctors(p);
+ pthread_mutex_unlock(&init_fini_lock);
+ if (!p->relocated && (mode & RTLD_LAZY)) {
+ prepare_lazy(p);
+ for (i=0; p->deps[i]; i++)
+ if (!p->deps[i]->relocated)
+ prepare_lazy(p->deps[i]);
}
- if (first_load || (mode & RTLD_GLOBAL)) {
+ if (!p->relocated || (mode & RTLD_GLOBAL)) {
/* Make new symbols global, at least temporarily, so we can do
* relocations. If not RTLD_GLOBAL, this is reverted below. */
add_syms(p);
for (i=0; p->deps[i]; i++)
add_syms(p->deps[i]);
}
- if (first_load) {
+ if (!p->relocated) {
reloc_all(p);
}
__release_ptc();
if (p) gencnt++;
pthread_rwlock_unlock(&lock);
- if (p) do_init_fini(orig_tail);
+ if (ctor_queue) {
+ do_init_fini(ctor_queue);
+ free(ctor_queue);
+ }
pthread_setcancelstate(cs, 0);
return p;
}
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