diff options
author | Brooks Moses <bmoses@google.com> | 2014-02-24 11:04:49 -0800 |
---|---|---|
committer | Brooks Moses <bmoses@google.com> | 2014-02-24 11:04:49 -0800 |
commit | 949ad730d57d30113a365cd9fa3f3a27e43f151b (patch) | |
tree | 8e4f09e77584bf8099513c4c1aa1053c5d3d7b52 | |
parent | 09ac904b124ff24467e684c233cf6a8de3b1ba6b (diff) | |
download | glibc-949ad730d57d30113a365cd9fa3f3a27e43f151b.tar.gz glibc-949ad730d57d30113a365cd9fa3f3a27e43f151b.tar.xz glibc-949ad730d57d30113a365cd9fa3f3a27e43f151b.zip |
Revert upstream removal of async-safe TLS patches.
-rw-r--r-- | README.google | 17 | ||||
-rw-r--r-- | elf/Versions | 1 | ||||
-rw-r--r-- | elf/dl-misc.c | 142 | ||||
-rw-r--r-- | elf/dl-open.c | 5 | ||||
-rw-r--r-- | elf/dl-reloc.c | 48 | ||||
-rw-r--r-- | elf/dl-tls.c | 144 | ||||
-rw-r--r-- | nptl/Makefile | 12 | ||||
-rw-r--r-- | nptl/allocatestack.c | 19 | ||||
-rw-r--r-- | nptl/tst-tls7.c | 143 | ||||
-rw-r--r-- | nptl/tst-tls7mod.c | 40 | ||||
-rw-r--r-- | sysdeps/generic/ldsodefs.h | 16 | ||||
-rw-r--r-- | sysdeps/mach/hurd/dl-sysdep.h | 7 | ||||
-rw-r--r-- | sysdeps/unix/sysv/linux/dl-sysdep.c | 46 | ||||
-rw-r--r-- | sysdeps/unix/sysv/linux/dl-sysdep.h | 4 |
14 files changed, 579 insertions, 65 deletions
diff --git a/README.google b/README.google index 957b95b3e9..e2780b0bbc 100644 --- a/README.google +++ b/README.google @@ -18,3 +18,20 @@ have been checked in to (or back-ported from) the upstream sources. When checking in changes made upstream, add an entry to this file but DO NOT add entries to the GNU ChangeLog files. +elf/Versions +elf/dl-misc.c +elf/dl-open.c +elf/dl-reloc.c +elf/dl-tls.c +nptl/Makefile +nptl/allocatestack.c +nptl/tst-tls7.c +nptl/tst-tls7mod.c +sysdeps/generic/ldsodefs.h + Revert upstream removal of async-safe TLS patches. These patches were + removed at the last minute from the glibc 2.19 release, as follows: + https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=8b6785f0836011cace9a77f3c24e51a7379238a0 + https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=dd654bf9ba1848bf9ed250f8ebaa5097c383dcf8 + https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=73d61e4f6c65da714c0f8a3a233725322553ceba + https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=bf06bcee84d4c19a99925c0f58026a8cbd87a688 + (ahh, not yet upstream) diff --git a/elf/Versions b/elf/Versions index 238399232d..01b7a59d5e 100644 --- a/elf/Versions +++ b/elf/Versions @@ -53,6 +53,7 @@ ld { _dl_allocate_tls; _dl_allocate_tls_init; _dl_argv; _dl_find_dso_for_object; _dl_get_tls_static_info; _dl_deallocate_tls; _dl_make_stack_executable; _dl_out_of_memory; + _dl_clear_dtv; _dl_rtld_di_serinfo; _dl_starting_up; _dl_tls_setup; _rtld_global; _rtld_global_ro; diff --git a/elf/dl-misc.c b/elf/dl-misc.c index 8fd67100e3..043185aa7e 100644 --- a/elf/dl-misc.c +++ b/elf/dl-misc.c @@ -19,6 +19,7 @@ #include <assert.h> #include <fcntl.h> #include <ldsodefs.h> +#include <libc-symbols.h> #include <limits.h> #include <link.h> #include <stdarg.h> @@ -364,3 +365,144 @@ _dl_higher_prime_number (unsigned long int n) return *low; } + +/* To support accessing TLS variables from signal handlers, we need an + async signal safe memory allocator. These routines are never + themselves invoked reentrantly (all calls to them are surrounded by + signal masks) but may be invoked concurrently from many threads. + The current implementation is not particularly performant nor space + efficient, but it will be used rarely (and only in binaries that use + dlopen.) The API matches that of malloc() and friends. */ + +struct __signal_safe_allocator_header +{ + size_t size; + void *start; +}; + +static inline struct __signal_safe_allocator_header * +ptr_to_signal_safe_allocator_header (void *ptr) +{ + return (struct __signal_safe_allocator_header *) + ((char *) (ptr) - sizeof (struct __signal_safe_allocator_header)); +} + +void *weak_function +__signal_safe_memalign (size_t boundary, size_t size) +{ + struct __signal_safe_allocator_header *header; + + if (boundary < sizeof (*header)) + boundary = sizeof (*header); + + /* Boundary must be a power of two. */ + if (!powerof2 (boundary)) + return NULL; + + size_t pg = GLRO (dl_pagesize); + size_t padded_size; + if (boundary <= pg) + { + /* We'll get a pointer certainly aligned to boundary, so just + add one more boundary-sized chunk to hold the header. */ + padded_size = roundup (size, boundary) + boundary; + } + else + { + /* If we want K pages aligned to a J-page boundary, K+J+1 pages + contains at least one such region that isn't directly at the start + (so we can place the header.) This is wasteful, but you're the one + who wanted 64K-aligned TLS. */ + padded_size = roundup (size, pg) + boundary + pg; + } + + + size_t actual_size = roundup (padded_size, pg); + void *actual = mmap (NULL, actual_size, PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); + if (actual == MAP_FAILED) + return NULL; + + if (boundary <= pg) + { + header = actual + boundary - sizeof (*header); + } + else + { + intptr_t actual_pg = ((intptr_t) actual) / pg; + intptr_t boundary_pg = boundary / pg; + intptr_t start_pg = actual_pg + boundary_pg; + start_pg -= start_pg % boundary_pg; + if (start_pg > (actual_pg + 1)) + { + int ret = munmap (actual, (start_pg - actual_pg - 1) * pg); + assert (ret == 0); + actual = (void *) ((start_pg - 1) * pg); + } + char *start = (void *) (start_pg * pg); + header = ptr_to_signal_safe_allocator_header (start); + } + + header->size = actual_size; + header->start = actual; + void *ptr = header; + ptr += sizeof (*header); + if (((intptr_t) ptr) % boundary != 0) + _dl_fatal_printf ("__signal_safe_memalign produced incorrect alignment\n"); + return ptr; +} + +void * weak_function +__signal_safe_malloc (size_t size) +{ + return __signal_safe_memalign (1, size); +} + +void weak_function +__signal_safe_free (void *ptr) +{ + if (ptr == NULL) + return; + + struct __signal_safe_allocator_header *header + = ptr_to_signal_safe_allocator_header (ptr); + int ret = munmap (header->start, header->size); + + assert (ret == 0); +} + +void * weak_function +__signal_safe_realloc (void *ptr, size_t size) +{ + if (size == 0) + { + __signal_safe_free (ptr); + return NULL; + } + if (ptr == NULL) + return __signal_safe_malloc (size); + + struct __signal_safe_allocator_header *header + = ptr_to_signal_safe_allocator_header (ptr); + size_t old_size = header->size; + if (old_size - sizeof (*header) >= size) + return ptr; + + void *new_ptr = __signal_safe_malloc (size); + if (new_ptr == NULL) + return NULL; + + memcpy (new_ptr, ptr, old_size); + __signal_safe_free (ptr); + + return new_ptr; +} + +void * weak_function +__signal_safe_calloc (size_t nmemb, size_t size) +{ + void *ptr = __signal_safe_malloc (nmemb * size); + if (ptr == NULL) + return NULL; + return memset (ptr, 0, nmemb * size); +} diff --git a/elf/dl-open.c b/elf/dl-open.c index a9ca6b3b44..ea222d03e1 100644 --- a/elf/dl-open.c +++ b/elf/dl-open.c @@ -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); } diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c index 1f66fccee2..81ee47eb62 100644 --- a/elf/dl-reloc.c +++ b/elf/dl-reloc.c @@ -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")); diff --git a/elf/dl-tls.c b/elf/dl-tls.c index dbaea0aa91..50ec876eae 100644 --- a/elf/dl-tls.c +++ b/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> @@ -293,7 +294,7 @@ allocate_dtv (void *result) initial set of modules. This should avoid in most cases expansions of the dtv. */ dtv_length = GL(dl_tls_max_dtv_idx) + DTV_SURPLUS; - dtv = calloc (dtv_length + 2, sizeof (dtv_t)); + dtv = __signal_safe_calloc (dtv_length + 2, sizeof (dtv_t)); if (dtv != NULL) { /* This is the initial length of the dtv. */ @@ -463,6 +464,18 @@ _dl_allocate_tls (void *mem) } rtld_hidden_def (_dl_allocate_tls) +void +internal_function +_dl_clear_dtv (dtv_t *dtv) +{ + for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt) + if (! dtv[1 + cnt].pointer.is_static + && dtv[1 + cnt].pointer.val != TLS_DTV_UNALLOCATED) + __signal_safe_free (dtv[1 + cnt].pointer.val); + memset (dtv, '\0', (dtv[-1].counter + 1) * sizeof (dtv_t)); +} + +rtld_hidden_def (_dl_clear_dtv) #ifndef SHARED extern dtv_t _dl_static_dtv[]; @@ -479,11 +492,11 @@ _dl_deallocate_tls (void *tcb, bool dealloc_tcb) for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt) if (! dtv[1 + cnt].pointer.is_static && dtv[1 + cnt].pointer.val != TLS_DTV_UNALLOCATED) - free (dtv[1 + cnt].pointer.val); + __signal_safe_free (dtv[1 + cnt].pointer.val); /* The array starts with dtv[-1]. */ if (dtv != GL(dl_initial_dtv)) - free (dtv - 1); + __signal_safe_free (dtv - 1); if (dealloc_tcb) { @@ -521,20 +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 = __libc_memalign (map->l_tls_align, map->l_tls_blocksize); + 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; } @@ -576,7 +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 @@ -596,25 +618,27 @@ _dl_update_slotinfo (unsigned long int req_modid) if (gen <= dtv[0].counter) continue; + size_t modid = total + cnt; + /* If there is no map this means the entry is empty. */ struct link_map *map = listp->slotinfo[cnt].map; if (map == NULL) { /* If this modid was used at some point the memory might still be allocated. */ - if (! dtv[total + cnt].pointer.is_static - && dtv[total + cnt].pointer.val != TLS_DTV_UNALLOCATED) + if (dtv[-1].counter >= modid + && !dtv[modid].pointer.is_static + && dtv[modid].pointer.val != TLS_DTV_UNALLOCATED) { - free (dtv[total + cnt].pointer.val); - dtv[total + cnt].pointer.val = TLS_DTV_UNALLOCATED; + __signal_safe_free (dtv[modid].pointer.val); + dtv[modid].pointer.val = TLS_DTV_UNALLOCATED; } continue; } + assert (modid == map->l_tls_modid); /* Check whether the current dtv array is large enough. */ - size_t modid = map->l_tls_modid; - assert (total + cnt == modid); if (dtv[-1].counter < modid) { /* Reallocate the dtv. */ @@ -628,17 +652,18 @@ _dl_update_slotinfo (unsigned long int req_modid) { /* This is the initial dtv that was allocated during rtld startup using the dl-minimal.c - malloc instead of the real malloc. We can't + malloc instead of the real allocator. We can't free it, we have to abandon the old storage. */ - newp = malloc ((2 + newsize) * sizeof (dtv_t)); + newp = __signal_safe_malloc ( + (2 + newsize) * sizeof (dtv_t)); if (newp == NULL) oom (); memcpy (newp, &dtv[-1], (2 + oldsize) * sizeof (dtv_t)); } else { - newp = realloc (&dtv[-1], + newp = __signal_safe_realloc (&dtv[-1], (2 + newsize) * sizeof (dtv_t)); if (newp == NULL) oom (); @@ -668,7 +693,7 @@ _dl_update_slotinfo (unsigned long int req_modid) deallocate even if it is this dtv entry we are supposed to load. The reason is that we call memalign and not malloc. */ - free (dtv[modid].pointer.val); + __signal_safe_free (dtv[modid].pointer.val); /* This module is loaded dynamically- We defer memory allocation. */ @@ -685,6 +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; @@ -710,39 +737,60 @@ tls_get_addr_tail (GET_ADDR_ARGS, dtv_t *dtv, struct link_map *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; } diff --git a/nptl/Makefile b/nptl/Makefile index 57cc8c69e4..a43e740847 100644 --- a/nptl/Makefile +++ b/nptl/Makefile @@ -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 diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c index 13eca47cf2..2a5ac22117 100644 --- a/nptl/allocatestack.c +++ b/nptl/allocatestack.c @@ -242,11 +242,7 @@ get_cached_stack (size_t *sizep, void **memp) /* Clear the DTV. */ dtv_t *dtv = GET_DTV (TLS_TPADJ (result)); - for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt) - if (! dtv[1 + cnt].pointer.is_static - && dtv[1 + cnt].pointer.val != TLS_DTV_UNALLOCATED) - free (dtv[1 + cnt].pointer.val); - memset (dtv, '\0', (dtv[-1].counter + 1) * sizeof (dtv_t)); + _dl_clear_dtv (dtv); /* Re-initialize the TLS. */ _dl_allocate_tls_init (TLS_TPADJ (result)); @@ -1177,13 +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 diff --git a/nptl/tst-tls7.c b/nptl/tst-tls7.c new file mode 100644 index 0000000000..3e85a6ec85 --- /dev/null +++ b/nptl/tst-tls7.c @@ -0,0 +1,143 @@ +/* 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 <assert.h> +#include <atomic.h> +#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; +} + +static void (*tls7mod_action) (int, siginfo_t *, void *); + +static void +action (int signo, siginfo_t *info, void *ignored) +{ + sem_t *sem = info->si_value.sival_ptr; + + atomic_read_barrier (); + assert (tls7mod_action != NULL); + (*tls7mod_action) (signo, info, ignored); + + /* This sem_post may trigger dlclose, which will invalidate tls7mod_action. + It is important to do that only after tls7mod_action is no longer + active. */ + sem_post (sem); +} + +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); + } + + tls7mod_action = dlsym (h, "action"); + if (tls7mod_action == NULL) + { + puts ("dlsym for action failed"); + exit (1); + } + atomic_write_barrier (); + + 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"); + } + } + + /* Paranoia. */ + tls7mod_action = NULL; + + if (dlclose (h)) + { + puts ("dlclose failed"); + exit (1); + } + } + return 0; +} + +#define TIMEOUT 8 + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" diff --git a/nptl/tst-tls7mod.c b/nptl/tst-tls7mod.c new file mode 100644 index 0000000000..da5af56370 --- /dev/null +++ b/nptl/tst-tls7mod.c @@ -0,0 +1,40 @@ +/* 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) +{ + 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; +} diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index ffeb093887..72de344b9c 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -234,6 +234,11 @@ extern int _dl_name_match_p (const char *__name, const struct link_map *__map) extern unsigned long int _dl_higher_prime_number (unsigned long int n) internal_function; +/* Mask every signal, returning the previous sigmask in OLD. */ +extern void _dl_mask_all_signals (sigset_t *old) internal_function; +/* Undo _dl_mask_all_signals. */ +extern void _dl_unmask_signals (sigset_t *old) internal_function; + /* Function used as argument for `_dl_receive_error' function. The arguments are the error code, error string, and the objname the error occurred in. */ @@ -984,6 +989,17 @@ extern void *_dl_allocate_tls_storage (void) extern void *_dl_allocate_tls_init (void *) internal_function; rtld_hidden_proto (_dl_allocate_tls_init) +/* Remove all allocated dynamic TLS regions from a DTV + for reuse by new thread. */ +extern void _dl_clear_dtv (dtv_t *dtv) internal_function; +rtld_hidden_proto (_dl_clear_dtv) + +extern void *__signal_safe_memalign (size_t boundary, size_t size); +extern void *__signal_safe_malloc (size_t size); +extern void __signal_safe_free (void *ptr); +extern void *__signal_safe_realloc (void *ptr, size_t size); +extern void *__signal_safe_calloc (size_t nmemb, size_t size); + /* Deallocate memory allocated with _dl_allocate_tls. */ extern void _dl_deallocate_tls (void *tcb, bool dealloc_tcb) internal_function; rtld_hidden_proto (_dl_deallocate_tls) diff --git a/sysdeps/mach/hurd/dl-sysdep.h b/sysdeps/mach/hurd/dl-sysdep.h index 0b3158e57e..e7e209625b 100644 --- a/sysdeps/mach/hurd/dl-sysdep.h +++ b/sysdeps/mach/hurd/dl-sysdep.h @@ -29,3 +29,10 @@ # define DL_ARGV_NOT_RELRO 1 # define LIBC_STACK_END_NOT_RELRO 1 #endif + +#include <signal.h> +inline void _dl_mask_all_signals (sigset_t *) internal_function; +inline void _dl_mask_all_signals (sigset_t *) { } + +inline void _dl_unmask_all_signals (sigset_t *) internal_function; +inline void _dl_unmask_all_signals (sigset_t *) { } diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.c b/sysdeps/unix/sysv/linux/dl-sysdep.c index 28100742f5..676c9b246f 100644 --- a/sysdeps/unix/sysv/linux/dl-sysdep.c +++ b/sysdeps/unix/sysv/linux/dl-sysdep.c @@ -19,6 +19,7 @@ /* Linux needs some special initialization, but otherwise uses the generic dynamic linker system interface code. */ +#include <assert.h> #include <string.h> #include <fcntl.h> #include <unistd.h> @@ -130,3 +131,48 @@ _dl_discover_osversion (void) return version; } + +/* Mask every signal, returning the previous sigmask in OLD. */ +void +internal_function +_dl_mask_all_signals (sigset_t *old) +{ + int ret; + sigset_t new; + + sigfillset (&new); + + /* This function serves as a replacement to pthread_sigmask, which + isn't available from within the dynamic linker since it would require + linking with libpthread. We duplicate some of the functionality here + to avoid requiring libpthread. This isn't quite identical to + pthread_sigmask in that we do not mask internal signals used for + cancellation and setxid handling. This disables asynchronous + cancellation for the duration the signals are disabled, but it's a + small window, and prevents any problems with the use of TLS variables + in the signal handlers that would have executed. */ + + /* It's very important we don't touch errno here, as that's TLS; since this + gets called from get_tls_addr we might end up recursing. */ + + INTERNAL_SYSCALL_DECL (err); + + ret = INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &new, old, + _NSIG / 8); + + assert (ret == 0); +} + +/* Return sigmask to what it was before a call to _dl_mask_all_signals. */ +void +internal_function +_dl_unmask_signals (sigset_t *old) +{ + int ret; + INTERNAL_SYSCALL_DECL (err); + + ret = INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, old, NULL, + _NSIG / 8); + + assert (ret == 0); +} diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.h b/sysdeps/unix/sysv/linux/dl-sysdep.h index 096019f2a1..8e39c83217 100644 --- a/sysdeps/unix/sysv/linux/dl-sysdep.h +++ b/sysdeps/unix/sysv/linux/dl-sysdep.h @@ -30,4 +30,8 @@ /* Get version of the OS. */ extern int _dl_discover_osversion (void) attribute_hidden; # define HAVE_DL_DISCOVER_OSVERSION 1 + +#include <signal.h> +void _dl_mask_all_signals (sigset_t *) internal_function; +void _dl_unmask_all_signals (sigset_t *) internal_function; #endif |