+2014-01-03 Andrew Hunter <ahh@google.com>
+
+ * elf/dl-open.c (): New comment.
+ * elf/dl-reloc.c (_dl_try_allocate_static_tls): Use
+ atomic_compare_and_exchange_bool_acq
+ (_dl_allocate_static_tls): Block signals.
+ * elf/dl-tls.c (allocate_and_init): Return void.
+ (_dl_update_slotinfo): Block signals, use atomic update.
+
2014-01-03 Joseph Myers <joseph@codesourcery.com>
* math/auto-libm-test-in: Mark various tests with
generation of the DSO we are allocating data for. */
_dl_update_slotinfo (imap->l_tls_modid);
#endif
-
+ /* We do this iteration under a signal mask in dl-reloc; why not
+ here? Because these symbols are new and dlopen hasn't
+ returned yet. So we can't possibly be racing with a TLS
+ access to them from another thread. */
GL(dl_init_static_tls) (imap);
assert (imap->l_need_tls_init == 0);
}
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <atomic.h>
#include <errno.h>
#include <libintl.h>
+#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <ldsodefs.h>
size_t offset = GL(dl_tls_static_used) + (freebytes - n * map->l_tls_align
- map->l_tls_firstbyte_offset);
-
- map->l_tls_offset = GL(dl_tls_static_used) = offset;
#elif TLS_DTV_AT_TP
/* dl_tls_static_used includes the TCB at the beginning. */
size_t offset = (((GL(dl_tls_static_used)
if (used > GL(dl_tls_static_size))
goto fail;
- map->l_tls_offset = offset;
+#else
+# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
+#endif
+ /* We've computed the new value we want, now try to install it. */
+ ptrdiff_t val;
+ if ((val = map->l_tls_offset) == NO_TLS_OFFSET)
+ {
+ /* l_tls_offset starts out at NO_TLS_OFFSET, and all attempts to
+ change it go from NO_TLS_OFFSET to some other value. We use
+ compare_and_exchange to ensure only one attempt succeeds. We
+ don't actually need any memory ordering here, but _acq is the
+ weakest available. */
+ (void ) atomic_compare_and_exchange_bool_acq (&map->l_tls_offset,
+ offset,
+ NO_TLS_OFFSET);
+ val = map->l_tls_offset;
+ assert (val != NO_TLS_OFFSET);
+ }
+ if (val != offset)
+ {
+ /* We'd like to set a static offset for this section, but another
+ thread has already used a dynamic TLS block for it. Since we can
+ only use static offsets if everyone does (and it's not practical
+ to move that thread's dynamic block), we have to fail. */
+ goto fail;
+ }
+ /* We installed the value; now update the globals. */
+#if TLS_TCB_AT_TP
+ GL(dl_tls_static_used) = offset;
+#elif TLS_DTV_AT_TP
map->l_tls_firstbyte_offset = GL(dl_tls_static_used);
GL(dl_tls_static_used) = used;
#else
internal_function __attribute_noinline__
_dl_allocate_static_tls (struct link_map *map)
{
- if (map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET
- || _dl_try_allocate_static_tls (map))
+ /* We wrap this in a signal mask because it has to iterate all threads
+ (including this one) and update this map's TLS entry. A signal handler
+ accessing TLS would try to do the same update and break. */
+ sigset_t old;
+ _dl_mask_all_signals (&old);
+ int err = -1;
+ if (map->l_tls_offset != FORCED_DYNAMIC_TLS_OFFSET)
+ err = _dl_try_allocate_static_tls (map);
+
+ _dl_unmask_signals (&old);
+ if (err != 0)
{
_dl_signal_error (0, map->l_name, NULL, N_("\
cannot allocate memory in static TLS block"));
<http://www.gnu.org/licenses/>. */
#include <assert.h>
+#include <atomic.h>
#include <errno.h>
#include <libintl.h>
#include <signal.h>
# endif
-static void *
-allocate_and_init (struct link_map *map)
+static void
+allocate_and_init (dtv_t *dtv, struct link_map *map)
{
void *newp;
newp = __signal_safe_memalign (map->l_tls_align, map->l_tls_blocksize);
if (newp == NULL)
oom ();
- /* Initialize the memory. */
+ /* Initialize the memory. Since this is our thread's space, we are
+ under a signal mask, and no one has touched this section before,
+ we can safely just overwrite whatever's there. */
memset (__mempcpy (newp, map->l_tls_initimage, map->l_tls_initimage_size),
'\0', map->l_tls_blocksize - map->l_tls_initimage_size);
- return newp;
+ dtv->pointer.val = newp;
}
the entry we need. */
size_t new_gen = listp->slotinfo[idx].gen;
size_t total = 0;
-
+ sigset_t old;
+
+ _dl_mask_all_signals (&old);
+ /* We use the signal mask as a lock against reentrancy here.
+ Check that a signal taken before the lock didn't already
+ update us. */
+ dtv = THREAD_DTV ();
+ if (dtv[0].counter >= listp->slotinfo[idx].gen)
+ goto out;
/* We have to look through the entire dtv slotinfo list. */
listp = GL(dl_tls_dtv_slotinfo_list);
do
/* This will be the new maximum generation counter. */
dtv[0].counter = new_gen;
+ out:
+ _dl_unmask_signals (&old);
}
return the_map;
the_map = listp->slotinfo[idx].map;
}
-
- again:
- /* Make sure that, if a dlopen running in parallel forces the
- variable into static storage, we'll wait until the address in the
- static TLS block is set up, and use that. If we're undecided
- yet, make sure we make the decision holding the lock as well. */
- if (__builtin_expect (the_map->l_tls_offset
- != FORCED_DYNAMIC_TLS_OFFSET, 0))
+ sigset_t old;
+ _dl_mask_all_signals (&old);
+
+ /* As with update_slotinfo, we use the sigmask as a check against
+ reentrancy. */
+ if (dtv[GET_ADDR_MODULE].pointer.val != TLS_DTV_UNALLOCATED)
+ goto out;
+
+ /* Synchronize against a parallel dlopen() forcing this variable
+ into static storage. If that happens, we have to be more careful
+ about initializing the area, as that dlopen() will be iterating
+ the threads to do so itself. */
+ ptrdiff_t offset;
+ if ((offset = the_map->l_tls_offset) == NO_TLS_OFFSET)
{
- __rtld_lock_lock_recursive (GL(dl_load_lock));
- if (__builtin_expect (the_map->l_tls_offset == NO_TLS_OFFSET, 1))
- {
- the_map->l_tls_offset = FORCED_DYNAMIC_TLS_OFFSET;
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
- }
- else
+ /* l_tls_offset starts out at NO_TLS_OFFSET, and all attempts to
+ change it go from NO_TLS_OFFSET to some other value. We use
+ compare_and_exchange to ensure only one attempt succeeds. We
+ don't actually need any memory ordering here, but _acq is the
+ weakest available. */
+ (void) atomic_compare_and_exchange_bool_acq (&the_map->l_tls_offset,
+ FORCED_DYNAMIC_TLS_OFFSET,
+ NO_TLS_OFFSET);
+ offset = the_map->l_tls_offset;
+ assert (offset != NO_TLS_OFFSET);
+ }
+ if (offset == FORCED_DYNAMIC_TLS_OFFSET)
+ {
+ allocate_and_init (&dtv[GET_ADDR_MODULE], the_map);
+ }
+ else
+ {
+ void **pp = &dtv[GET_ADDR_MODULE].pointer.val;
+ while (atomic_forced_read (*pp) == TLS_DTV_UNALLOCATED)
{
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
- if (__builtin_expect (the_map->l_tls_offset
- != FORCED_DYNAMIC_TLS_OFFSET, 1))
- {
- void *p = dtv[GET_ADDR_MODULE].pointer.val;
- if (__builtin_expect (p == TLS_DTV_UNALLOCATED, 0))
- goto again;
-
- return (char *) p + GET_ADDR_OFFSET;
- }
+ /* for lack of a better (safe) thing to do, just spin.
+ Someone else (not us; it's done under a signal mask) set
+ this map to a static TLS offset, and they'll iterate all
+ threads to initialize it. They'll eventually write
+ to pointer.val, at which point we know they've fully
+ completed initialization. */
+ atomic_delay ();
}
+ /* Make sure we've picked up their initialization of the actual
+ block; this pairs against the write barrier in
+ init_one_static_tls, guaranteeing that we see their write of
+ the tls_initimage into the static region. */
+ atomic_read_barrier ();
}
- void *p = dtv[GET_ADDR_MODULE].pointer.val = allocate_and_init (the_map);
- dtv[GET_ADDR_MODULE].pointer.is_static = false;
+out:
+ assert (dtv[GET_ADDR_MODULE].pointer.val != TLS_DTV_UNALLOCATED);
+ _dl_unmask_signals (&old);
- return (char *) p + GET_ADDR_OFFSET;
+ return (char *) dtv[GET_ADDR_MODULE].pointer.val + GET_ADDR_OFFSET;
}
-2011-12-12 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
+2014-01-03 Andrew Hunter <ahh@google.com>
+
+ * nptl/Makefile (tst-tls7): New test.
+ * nptl/tst-tls7.c: New file.
+ * nptl/tst-tls7mod.c: New file.
+ * nptl/allocatestack.c (init_one_static_tls): Use atomic barrier.
+
+2013-12-12 Adhemerval Zanella <azanella@linux.vnet.ibm.com>
* sysdeps/powerpc/tls.h (struct tcbhead_t): Add DSO and TAR fields.
* nptl/sysdeps/powerpc/tcb-offsets.sym: Likewise.
tst-oncex3 tst-oncex4
endif
ifeq ($(build-shared),yes)
-tests += tst-atfork2 tst-tls3 tst-tls4 tst-tls5 tst-_res1 tst-fini1 \
+tests += tst-atfork2 tst-tls3 tst-tls4 tst-tls5 tst-tls7 tst-_res1 tst-fini1 \
tst-stackguard1
tests-nolibpthread += tst-fini1
ifeq ($(have-z-execstack),yes)
modules-names = tst-atfork2mod tst-tls3mod tst-tls4moda tst-tls4modb \
tst-tls5mod tst-tls5moda tst-tls5modb tst-tls5modc \
tst-tls5modd tst-tls5mode tst-tls5modf \
- tst-_res1mod1 tst-_res1mod2 tst-execstack-mod tst-fini1mod
+ tst-_res1mod1 tst-_res1mod2 tst-execstack-mod tst-fini1mod \
+ tst-tls7mod
extra-test-objs += $(addsuffix .os,$(strip $(modules-names))) tst-cleanup4aux.o
test-extras += $(modules-names) tst-cleanup4aux
test-modules = $(addprefix $(objpfx),$(addsuffix .so,$(modules-names)))
tst-tls5modd.so-no-z-defs = yes
tst-tls5mode.so-no-z-defs = yes
tst-tls5modf.so-no-z-defs = yes
+tst-tls7mod.so-no-z-defs = yes
ifeq ($(build-shared),yes)
# Build all the modules even when not actually running test programs.
LDFLAGS-tst-tls5 = $(no-as-needed)
LDFLAGS-tst-tls5mod.so = -Wl,-soname,tst-tls5mod.so
+# ensure free(malloc()) isn't optimized out
+CFLAGS-tst-tls7.c = -fno-builtin-malloc -fno-builtin-free
+$(objpfx)tst-tls7: $(libdl) $(shared-thread-library)
+$(objpfx)tst-tls7.out: $(objpfx)tst-tls7mod.so
+$(objpfx)tst-tls7mod.so: $(shared-thread-library)
+
ifeq ($(build-shared),yes)
ifeq ($(run-built-tests),yes)
tests: $(objpfx)tst-tls6.out
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
# endif
- /* Fill in the DTV slot so that a later LD/GD access will find it. */
- dtv[map->l_tls_modid].pointer.val = dest;
- dtv[map->l_tls_modid].pointer.is_static = true;
-
/* Initialize the memory. */
memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size),
'\0', map->l_tls_blocksize - map->l_tls_initimage_size);
+
+ /* Fill in the DTV slot so that a later LD/GD access will find it. */
+ dtv[map->l_tls_modid].pointer.is_static = true;
+ /* Pairs against the read barrier in tls_get_attr_tail, guaranteeing
+ any thread waiting for an update to pointer.val sees the
+ initimage write. */
+ atomic_write_barrier ();
+ dtv[map->l_tls_modid].pointer.val = dest;
+
}
void
--- /dev/null
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+
+/* This test checks that TLS in a dlopened object works when first accessed
+ from a signal handler. */
+
+#include <dlfcn.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void *
+spin (void *ignored)
+{
+ while (1)
+ {
+ /* busywork */
+ free (malloc (128));
+ }
+
+ /* never reached */
+ return NULL;
+}
+
+int
+do_test (void)
+{
+ pthread_t th[10];
+
+ for (int i = 0; i < 10; ++i)
+ {
+ if (pthread_create (&th[i], NULL, spin, NULL))
+ {
+ puts ("pthread_create failed");
+ exit (1);
+ }
+ }
+#define NITERS 75
+
+ for (int i = 0; i < NITERS; ++i)
+ {
+ void *h = dlopen ("tst-tls7mod.so", RTLD_LAZY);
+ if (h == NULL)
+ {
+ puts ("dlopen failed");
+ exit (1);
+ }
+
+ void (*action) (int, siginfo_t *, void *) = dlsym (h, "action");
+ if (action == NULL)
+ {
+ puts ("dlsym for action failed");
+ exit (1);
+ }
+
+ struct sigaction sa;
+ sa.sa_sigaction = action;
+ sigemptyset (&sa.sa_mask);
+ sa.sa_flags = SA_SIGINFO;
+ if (sigaction (SIGUSR1, &sa, NULL))
+ {
+ puts ("sigaction failed");
+ exit (1);
+ }
+
+ sem_t sem;
+ if (sem_init (&sem, 0, 0))
+ {
+ puts ("sem_init failed");
+ }
+
+ sigval_t val;
+ val.sival_ptr = &sem;
+ for (int i = 0; i < 10; ++i)
+ {
+ if (pthread_sigqueue (th[i], SIGUSR1, val))
+ {
+ puts ("pthread_sigqueue failed");
+ }
+ }
+
+
+ for (int i = 0; i < 10; ++i)
+ {
+ if (sem_wait (&sem))
+ {
+ puts ("sem_wait failed");
+ }
+ }
+
+ if (dlclose (h))
+ {
+ puts ("dlclose failed");
+ exit (1);
+ }
+ }
+ return 0;
+}
+
+#define TIMEOUT 4
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
--- /dev/null
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* Dynamic module with TLS to be accessed by a signal handler to check safety
+ of that mode. */
+
+#include <semaphore.h>
+#include <signal.h>
+#include <unistd.h>
+
+/* This is an unlikely value to see in incorrectly initialized TLS
+ block -- make sure we're initialized properly. */
+static __thread intptr_t tls_data = 0xdeadbeef;
+
+void
+action (int signo, siginfo_t *info, void *ignored)
+{
+ sem_t *sem = info->si_value.sival_ptr;
+ if (tls_data != 0xdeadbeef)
+ {
+ write (STDOUT_FILENO, "wrong TLS value\n", 17);
+ _exit (1);
+ }
+
+ /* arbitrary choice, just write something unique-ish. */
+ tls_data = (intptr_t) info;
+
+ sem_post (sem);
+}
projects / platform / upstream / linaro-glibc.git / commitdiff