diff options
| -rw-r--r-- | elf/Makefile | 26 | ||||
| -rw-r--r-- | elf/dl-tls.c | 95 | ||||
| -rw-r--r-- | elf/rtld.c | 2 | ||||
| -rw-r--r-- | elf/tst-recursive-tls.c | 60 | ||||
| -rw-r--r-- | elf/tst-recursive-tlsmallocmod.c | 64 | ||||
| -rw-r--r-- | elf/tst-recursive-tlsmodN.c | 28 | ||||
| -rw-r--r-- | sysdeps/generic/ldsodefs.h | 14 | ||||
| -rw-r--r-- | sysdeps/x86_64/dl-tls.c | 5 |
8 files changed, 284 insertions, 10 deletions
diff --git a/elf/Makefile b/elf/Makefile index 1105bee..24ad522 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -445,6 +445,7 @@ tests += \ tst-p_align1 \ tst-p_align2 \ tst-p_align3 \ + tst-recursive-tls \ tst-relsort1 \ tst-ro-dynamic \ tst-rtld-run-static \ @@ -892,6 +893,23 @@ modules-names += \ tst-null-argv-lib \ tst-p_alignmod-base \ tst-p_alignmod3 \ + tst-recursive-tlsmallocmod \ + tst-recursive-tlsmod0 \ + tst-recursive-tlsmod1 \ + tst-recursive-tlsmod2 \ + tst-recursive-tlsmod3 \ + tst-recursive-tlsmod4 \ + tst-recursive-tlsmod5 \ + tst-recursive-tlsmod6 \ + tst-recursive-tlsmod7 \ + tst-recursive-tlsmod8 \ + tst-recursive-tlsmod9 \ + tst-recursive-tlsmod10 \ + tst-recursive-tlsmod11 \ + tst-recursive-tlsmod12 \ + tst-recursive-tlsmod13 \ + tst-recursive-tlsmod14 \ + tst-recursive-tlsmod15 \ tst-relsort1mod1 \ tst-relsort1mod2 \ tst-ro-dynamic-mod \ @@ -3099,3 +3117,11 @@ CFLAGS-tst-gnu2-tls2mod0.c += -mtls-dialect=$(have-mtls-descriptor) CFLAGS-tst-gnu2-tls2mod1.c += -mtls-dialect=$(have-mtls-descriptor) CFLAGS-tst-gnu2-tls2mod2.c += -mtls-dialect=$(have-mtls-descriptor) endif + +$(objpfx)tst-recursive-tls: $(objpfx)tst-recursive-tlsmallocmod.so +# More objects than DTV_SURPLUS, to trigger DTV reallocation. +$(objpfx)tst-recursive-tls.out: \ + $(patsubst %,$(objpfx)tst-recursive-tlsmod%.so, \ + 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15) +$(objpfx)tst-recursive-tlsmod%.os: tst-recursive-tlsmodN.c + $(compile-command.c) -DVAR=thread_$* -DFUNC=get_threadvar_$* diff --git a/elf/dl-tls.c b/elf/dl-tls.c index 670dbc4..3d22127 100644 --- a/elf/dl-tls.c +++ b/elf/dl-tls.c @@ -75,6 +75,31 @@ /* Default for dl_tls_static_optional. */ #define OPTIONAL_TLS 512 +/* Used to count the number of threads currently executing dynamic TLS + updates. Used to avoid recursive malloc calls in __tls_get_addr + for an interposed malloc that uses global-dynamic TLS (which is not + recommended); see _dl_tls_allocate_active checks. This could be a + per-thread flag, but would need TLS access in the dynamic linker. */ +unsigned int _dl_tls_threads_in_update; + +static inline void +_dl_tls_allocate_begin (void) +{ + atomic_fetch_add_relaxed (&_dl_tls_threads_in_update, 1); +} + +static inline void +_dl_tls_allocate_end (void) +{ + atomic_fetch_add_relaxed (&_dl_tls_threads_in_update, -1); +} + +static inline bool +_dl_tls_allocate_active (void) +{ + return atomic_load_relaxed (&_dl_tls_threads_in_update) > 0; +} + /* Compute the static TLS surplus based on the namespace count and the TLS space that can be used for optimizations. */ static inline int @@ -425,12 +450,18 @@ _dl_allocate_tls_storage (void) size += TLS_PRE_TCB_SIZE; #endif - /* Perform the allocation. Reserve space for the required alignment - and the pointer to the original allocation. */ + /* Reserve space for the required alignment and the pointer to the + original allocation. */ size_t alignment = GLRO (dl_tls_static_align); + + /* Perform the allocation. */ + _dl_tls_allocate_begin (); void *allocated = malloc (size + alignment + sizeof (void *)); if (__glibc_unlikely (allocated == NULL)) - return NULL; + { + _dl_tls_allocate_end (); + return NULL; + } /* Perform alignment and allocate the DTV. */ #if TLS_TCB_AT_TP @@ -466,6 +497,8 @@ _dl_allocate_tls_storage (void) result = allocate_dtv (result); if (result == NULL) free (allocated); + + _dl_tls_allocate_end (); return result; } @@ -483,6 +516,7 @@ _dl_resize_dtv (dtv_t *dtv, size_t max_modid) size_t newsize = max_modid + DTV_SURPLUS; size_t oldsize = dtv[-1].counter; + _dl_tls_allocate_begin (); if (dtv == GL(dl_initial_dtv)) { /* This is the initial dtv that was either statically allocated in @@ -502,6 +536,7 @@ _dl_resize_dtv (dtv_t *dtv, size_t max_modid) if (newp == NULL) oom (); } + _dl_tls_allocate_end (); newp[0].counter = newsize; @@ -676,7 +711,9 @@ allocate_dtv_entry (size_t alignment, size_t size) if (powerof2 (alignment) && alignment <= _Alignof (max_align_t)) { /* The alignment is supported by malloc. */ + _dl_tls_allocate_begin (); void *ptr = malloc (size); + _dl_tls_allocate_end (); return (struct dtv_pointer) { ptr, ptr }; } @@ -688,7 +725,10 @@ allocate_dtv_entry (size_t alignment, size_t size) /* Perform the allocation. This is the pointer we need to free later. */ + _dl_tls_allocate_begin (); void *start = malloc (alloc_size); + _dl_tls_allocate_end (); + if (start == NULL) return (struct dtv_pointer) {}; @@ -826,7 +866,11 @@ _dl_update_slotinfo (unsigned long int req_modid, size_t new_gen) free implementation. Checking here papers over at least some dynamic TLS usage by interposed mallocs. */ if (dtv[modid].pointer.to_free != NULL) - free (dtv[modid].pointer.to_free); + { + _dl_tls_allocate_begin (); + free (dtv[modid].pointer.to_free); + _dl_tls_allocate_end (); + } dtv[modid].pointer.val = TLS_DTV_UNALLOCATED; dtv[modid].pointer.to_free = NULL; @@ -956,10 +1000,22 @@ __tls_get_addr (GET_ADDR_ARGS) size_t gen = atomic_load_relaxed (&GL(dl_tls_generation)); if (__glibc_unlikely (dtv[0].counter != gen)) { - /* Update DTV up to the global generation, see CONCURRENCY NOTES - in _dl_update_slotinfo. */ - gen = atomic_load_acquire (&GL(dl_tls_generation)); - return update_get_addr (GET_ADDR_PARAM, gen); + if (_dl_tls_allocate_active () + && GET_ADDR_MODULE < _dl_tls_initial_modid_limit) + /* This is a reentrant __tls_get_addr call, but we can + satisfy it because it's an initially-loaded module ID. + These TLS slotinfo slots do not change, so the + out-of-date generation counter does not matter. However, + if not in a TLS update, still update_get_addr below, to + get off the slow path eventually. */ + ; + else + { + /* Update DTV up to the global generation, see CONCURRENCY NOTES + in _dl_update_slotinfo. */ + gen = atomic_load_acquire (&GL(dl_tls_generation)); + return update_get_addr (GET_ADDR_PARAM, gen); + } } void *p = dtv[GET_ADDR_MODULE].pointer.val; @@ -969,7 +1025,7 @@ __tls_get_addr (GET_ADDR_ARGS) return (char *) p + GET_ADDR_OFFSET; } -#endif +#endif /* SHARED */ /* Look up the module's TLS block as for __tls_get_addr, @@ -1018,6 +1074,25 @@ _dl_tls_get_addr_soft (struct link_map *l) return data; } +size_t _dl_tls_initial_modid_limit; + +void +_dl_tls_initial_modid_limit_setup (void) +{ + struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list); + size_t idx; + for (idx = 0; idx < listp->len; ++idx) + { + struct link_map *l = listp->slotinfo[idx].map; + if (l == NULL + /* The object can be unloaded, so its modid can be + reassociated. */ + || !(l->l_type == lt_executable || l->l_type == lt_library)) + break; + } + _dl_tls_initial_modid_limit = idx; +} + void _dl_add_to_slotinfo (struct link_map *l, bool do_add) @@ -1050,9 +1125,11 @@ _dl_add_to_slotinfo (struct link_map *l, bool do_add) the first slot. */ assert (idx == 0); + _dl_tls_allocate_begin (); listp = (struct dtv_slotinfo_list *) malloc (sizeof (struct dtv_slotinfo_list) + TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo)); + _dl_tls_allocate_end (); if (listp == NULL) { /* We ran out of memory while resizing the dtv slotinfo list. */ @@ -788,6 +788,8 @@ init_tls (size_t naudit) _dl_fatal_printf ("\ cannot allocate TLS data structures for initial thread\n"); + _dl_tls_initial_modid_limit_setup (); + /* Store for detection of the special case by __tls_get_addr so it knows not to pass this dtv to the normal realloc. */ GL(dl_initial_dtv) = GET_DTV (tcbp); diff --git a/elf/tst-recursive-tls.c b/elf/tst-recursive-tls.c new file mode 100644 index 0000000..716d1f7 --- /dev/null +++ b/elf/tst-recursive-tls.c @@ -0,0 +1,60 @@ +/* Test with interposed malloc with dynamic TLS. + Copyright (C) 2024 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 + <https://www.gnu.org/licenses/>. */ + +#include <array_length.h> +#include <stdio.h> +#include <support/check.h> +#include <support/xdlfcn.h> + +/* Defined in tst-recursive-tlsmallocmod.so. */ +extern __thread unsigned int malloc_subsytem_counter; + +static int +do_test (void) +{ + /* 16 is large enough to exercise the DTV resizing case. */ + void *handles[16]; + + for (unsigned int i = 0; i < array_length (handles); ++i) + { + /* Re-use the TLS slot for module 0. */ + if (i > 0) + xdlclose (handles[0]); + + char soname[30]; + snprintf (soname, sizeof (soname), "tst-recursive-tlsmod%u.so", i); + handles[i] = xdlopen (soname, RTLD_NOW); + + if (i > 0) + { + handles[0] = xdlopen ("tst-recursive-tlsmod0.so", RTLD_NOW); + int (*fptr) (void) = xdlsym (handles[0], "get_threadvar_0"); + /* May trigger TLS storage allocation using malloc. */ + TEST_COMPARE (fptr (), 0); + } + } + + for (unsigned int i = 0; i < array_length (handles); ++i) + xdlclose (handles[i]); + + printf ("info: malloc subsystem calls: %u\n", malloc_subsytem_counter); + TEST_VERIFY (malloc_subsytem_counter > 0); + return 0; +} + +#include <support/test-driver.c> diff --git a/elf/tst-recursive-tlsmallocmod.c b/elf/tst-recursive-tlsmallocmod.c new file mode 100644 index 0000000..c24e994 --- /dev/null +++ b/elf/tst-recursive-tlsmallocmod.c @@ -0,0 +1,64 @@ +/* Interposed malloc with dynamic TLS. + Copyright (C) 2024 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 + <https://www.gnu.org/licenses/>. */ + +#include <stdlib.h> +#include <dlfcn.h> + +__thread unsigned int malloc_subsytem_counter; + +static __typeof (malloc) *malloc_fptr; +static __typeof (free) *free_fptr; +static __typeof (calloc) *calloc_fptr; +static __typeof (realloc) *realloc_fptr; + +static void __attribute__ ((constructor)) +init (void) +{ + malloc_fptr = dlsym (RTLD_NEXT, "malloc"); + free_fptr = dlsym (RTLD_NEXT, "free"); + calloc_fptr = dlsym (RTLD_NEXT, "calloc"); + realloc_fptr = dlsym (RTLD_NEXT, "realloc"); +} + +void * +malloc (size_t size) +{ + ++malloc_subsytem_counter; + return malloc_fptr (size); +} + +void +free (void *ptr) +{ + ++malloc_subsytem_counter; + return free_fptr (ptr); +} + +void * +calloc (size_t a, size_t b) +{ + ++malloc_subsytem_counter; + return calloc_fptr (a, b); +} + +void * +realloc (void *ptr, size_t size) +{ + ++malloc_subsytem_counter; + return realloc_fptr (ptr, size); +} diff --git a/elf/tst-recursive-tlsmodN.c b/elf/tst-recursive-tlsmodN.c new file mode 100644 index 0000000..bb7592a --- /dev/null +++ b/elf/tst-recursive-tlsmodN.c @@ -0,0 +1,28 @@ +/* Test module with global-dynamic TLS. Used to trigger DTV reallocation. + Copyright (C) 2024 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 + <https://www.gnu.org/licenses/>. */ + +/* Compiled with VAR and FUNC set via -D. FUNC requires some + relocation against TLS variable VAR. */ + +__thread int VAR; + +int +FUNC (void) +{ + return VAR; +} diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 50f58a6..656e8a3 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -1256,6 +1256,20 @@ extern struct link_map *_dl_update_slotinfo (unsigned long int req_modid, size_t gen) attribute_hidden; +/* The last TLS module ID that is initially loaded, plus 1. TLS + addresses for modules with IDs lower than that can be obtained from + the DTV even if its generation is outdated. */ +extern size_t _dl_tls_initial_modid_limit attribute_hidden attribute_relro; + +/* Compute _dl_tls_initial_modid_limit. To be called after initial + relocation. */ +void _dl_tls_initial_modid_limit_setup (void) attribute_hidden; + +/* Number of threads currently in a TLS update. This is used to + detect reentrant __tls_get_addr calls without a per-thread + flag. */ +extern unsigned int _dl_tls_threads_in_update attribute_hidden; + /* Look up the module's TLS block as for __tls_get_addr, but never touch anything. Return null if it's not allocated yet. */ extern void *_dl_tls_get_addr_soft (struct link_map *l) attribute_hidden; diff --git a/sysdeps/x86_64/dl-tls.c b/sysdeps/x86_64/dl-tls.c index 869023b..b3c1e4f 100644 --- a/sysdeps/x86_64/dl-tls.c +++ b/sysdeps/x86_64/dl-tls.c @@ -41,7 +41,10 @@ __tls_get_addr_slow (GET_ADDR_ARGS) dtv_t *dtv = THREAD_DTV (); size_t gen = atomic_load_acquire (&GL(dl_tls_generation)); - if (__glibc_unlikely (dtv[0].counter != gen)) + if (__glibc_unlikely (dtv[0].counter != gen) + /* See comment in __tls_get_addr in elf/dl-tls.c. */ + && !(_dl_tls_allocate_active () + && GET_ADDR_MODULE < _dl_tls_initial_modid_limit)) return update_get_addr (GET_ADDR_PARAM, gen); return tls_get_addr_tail (GET_ADDR_PARAM, dtv, NULL); |