Async-signal safe TLS.
ChangeLog: 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. nptl/ChangeLog: 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.
This commit is contained in:
Andrew Hunter
Paul Pluzhnikov
parent
7dd009d865
commit
7f507ee17a
|
|
@ -1,3 +1,12 @@
|
|||
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
|
||||
|
|
|
|||
|
|
@ -548,7 +548,10 @@ cannot load any more object with static TLS"));
|
|||
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);
|
||||
}
|
||||
|
|
|
|||
|
|
@ -16,8 +16,10 @@
|
|||
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>
|
||||
|
|
@ -70,8 +72,6 @@ _dl_try_allocate_static_tls (struct link_map *map)
|
|||
|
||||
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)
|
||||
|
|
@ -83,7 +83,36 @@ _dl_try_allocate_static_tls (struct link_map *map)
|
|||
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
|
||||
|
|
@ -114,8 +143,17 @@ void
|
|||
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"));
|
||||
|
|
|
|||
100
elf/dl-tls.c
100
elf/dl-tls.c
|
|
@ -17,6 +17,7 @@
|
|||
<http://www.gnu.org/licenses/>. */
|
||||
|
||||
#include <assert.h>
|
||||
#include <atomic.h>
|
||||
#include <errno.h>
|
||||
#include <libintl.h>
|
||||
#include <signal.h>
|
||||
|
|
@ -533,19 +534,21 @@ rtld_hidden_def (_dl_deallocate_tls)
|
|||
# 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;
|
||||
}
|
||||
|
||||
|
||||
|
|
@ -587,7 +590,15 @@ _dl_update_slotinfo (unsigned long int req_modid)
|
|||
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
|
||||
|
|
@ -699,6 +710,8 @@ _dl_update_slotinfo (unsigned long int req_modid)
|
|||
|
||||
/* This will be the new maximum generation counter. */
|
||||
dtv[0].counter = new_gen;
|
||||
out:
|
||||
_dl_unmask_signals (&old);
|
||||
}
|
||||
|
||||
return the_map;
|
||||
|
|
@ -724,39 +737,60 @@ tls_get_addr_tail (GET_ADDR_ARGS, dtv_t *dtv, struct link_map *the_map)
|
|||
|
||||
the_map = listp->slotinfo[idx].map;
|
||||
}
|
||||
sigset_t old;
|
||||
_dl_mask_all_signals (&old);
|
||||
|
||||
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))
|
||||
/* 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
|
||||
{
|
||||
__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;
|
||||
}
|
||||
}
|
||||
/* 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);
|
||||
}
|
||||
void *p = dtv[GET_ADDR_MODULE].pointer.val = allocate_and_init (the_map);
|
||||
dtv[GET_ADDR_MODULE].pointer.is_static = false;
|
||||
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)
|
||||
{
|
||||
/* 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 ();
|
||||
}
|
||||
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;
|
||||
}
|
||||
|
||||
|
||||
|
|
|
|||
|
|
@ -1,4 +1,11 @@
|
|||
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.
|
||||
|
|
|
|||
|
|
@ -293,7 +293,7 @@ tests += tst-cancelx2 tst-cancelx3 tst-cancelx4 tst-cancelx5 \
|
|||
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)
|
||||
|
|
@ -304,7 +304,8 @@ endif
|
|||
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,$(modules-names)))
|
||||
|
|
@ -318,6 +319,7 @@ tst-tls5modc.so-no-z-defs = yes
|
|||
tst-tls5modd.so-no-z-defs = yes
|
||||
tst-tls5mode.so-no-z-defs = yes
|
||||
tst-tls5modf.so-no-z-defs = yes
|
||||
tst-tls7mod.so-no-z-defs = yes
|
||||
|
||||
ifeq ($(build-shared),yes)
|
||||
# Build all the modules even when not actually running test programs.
|
||||
|
|
@ -480,6 +482,12 @@ $(objpfx)tst-tls5: $(objpfx)tst-tls5mod.so $(shared-thread-library)
|
|||
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
|
||||
|
|
|
|||
|
|
@ -1173,13 +1173,18 @@ init_one_static_tls (struct pthread *curp, struct link_map *map)
|
|||
# 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
|
||||
|
|
|
|||
|
|
@ -0,0 +1,120 @@
|
|||
/* 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"
|
||||
|
|
@ -0,0 +1,43 @@
|
|||
/* 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);
|
||||
}
|
||||
Loading…
Reference in New Issue