diff options
Diffstat (limited to 'REORG.TODO/elf/dl-tls.c')
| -rw-r--r-- | REORG.TODO/elf/dl-tls.c | 953 |
1 files changed, 953 insertions, 0 deletions
diff --git a/REORG.TODO/elf/dl-tls.c b/REORG.TODO/elf/dl-tls.c new file mode 100644 index 0000000000..5aba33b3fa --- /dev/null +++ b/REORG.TODO/elf/dl-tls.c @@ -0,0 +1,953 @@ +/* Thread-local storage handling in the ELF dynamic linker. Generic version. + Copyright (C) 2002-2017 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/>. */ + +#include <assert.h> +#include <errno.h> +#include <libintl.h> +#include <signal.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/param.h> +#include <atomic.h> + +#include <tls.h> +#include <dl-tls.h> +#include <ldsodefs.h> + +/* Amount of excess space to allocate in the static TLS area + to allow dynamic loading of modules defining IE-model TLS data. */ +#define TLS_STATIC_SURPLUS 64 + DL_NNS * 100 + + +/* Out-of-memory handler. */ +static void +__attribute__ ((__noreturn__)) +oom (void) +{ + _dl_fatal_printf ("cannot allocate memory for thread-local data: ABORT\n"); +} + + +size_t +internal_function +_dl_next_tls_modid (void) +{ + size_t result; + + if (__builtin_expect (GL(dl_tls_dtv_gaps), false)) + { + size_t disp = 0; + struct dtv_slotinfo_list *runp = GL(dl_tls_dtv_slotinfo_list); + + /* Note that this branch will never be executed during program + start since there are no gaps at that time. Therefore it + does not matter that the dl_tls_dtv_slotinfo is not allocated + yet when the function is called for the first times. + + NB: the offset +1 is due to the fact that DTV[0] is used + for something else. */ + result = GL(dl_tls_static_nelem) + 1; + if (result <= GL(dl_tls_max_dtv_idx)) + do + { + while (result - disp < runp->len) + { + if (runp->slotinfo[result - disp].map == NULL) + break; + + ++result; + assert (result <= GL(dl_tls_max_dtv_idx) + 1); + } + + if (result - disp < runp->len) + break; + + disp += runp->len; + } + while ((runp = runp->next) != NULL); + + if (result > GL(dl_tls_max_dtv_idx)) + { + /* The new index must indeed be exactly one higher than the + previous high. */ + assert (result == GL(dl_tls_max_dtv_idx) + 1); + /* There is no gap anymore. */ + GL(dl_tls_dtv_gaps) = false; + + goto nogaps; + } + } + else + { + /* No gaps, allocate a new entry. */ + nogaps: + + result = ++GL(dl_tls_max_dtv_idx); + } + + return result; +} + + +size_t +internal_function +_dl_count_modids (void) +{ + /* It is rare that we have gaps; see elf/dl-open.c (_dl_open) where + we fail to load a module and unload it leaving a gap. If we don't + have gaps then the number of modids is the current maximum so + return that. */ + if (__glibc_likely (!GL(dl_tls_dtv_gaps))) + return GL(dl_tls_max_dtv_idx); + + /* We have gaps and are forced to count the non-NULL entries. */ + size_t n = 0; + struct dtv_slotinfo_list *runp = GL(dl_tls_dtv_slotinfo_list); + while (runp != NULL) + { + for (size_t i = 0; i < runp->len; ++i) + if (runp->slotinfo[i].map != NULL) + ++n; + + runp = runp->next; + } + + return n; +} + + +#ifdef SHARED +void +internal_function +_dl_determine_tlsoffset (void) +{ + size_t max_align = TLS_TCB_ALIGN; + size_t freetop = 0; + size_t freebottom = 0; + + /* The first element of the dtv slot info list is allocated. */ + assert (GL(dl_tls_dtv_slotinfo_list) != NULL); + /* There is at this point only one element in the + dl_tls_dtv_slotinfo_list list. */ + assert (GL(dl_tls_dtv_slotinfo_list)->next == NULL); + + struct dtv_slotinfo *slotinfo = GL(dl_tls_dtv_slotinfo_list)->slotinfo; + + /* Determining the offset of the various parts of the static TLS + block has several dependencies. In addition we have to work + around bugs in some toolchains. + + Each TLS block from the objects available at link time has a size + and an alignment requirement. The GNU ld computes the alignment + requirements for the data at the positions *in the file*, though. + I.e, it is not simply possible to allocate a block with the size + of the TLS program header entry. The data is layed out assuming + that the first byte of the TLS block fulfills + + p_vaddr mod p_align == &TLS_BLOCK mod p_align + + This means we have to add artificial padding at the beginning of + the TLS block. These bytes are never used for the TLS data in + this module but the first byte allocated must be aligned + according to mod p_align == 0 so that the first byte of the TLS + block is aligned according to p_vaddr mod p_align. This is ugly + and the linker can help by computing the offsets in the TLS block + assuming the first byte of the TLS block is aligned according to + p_align. + + The extra space which might be allocated before the first byte of + the TLS block need not go unused. The code below tries to use + that memory for the next TLS block. This can work if the total + memory requirement for the next TLS block is smaller than the + gap. */ + +#if TLS_TCB_AT_TP + /* We simply start with zero. */ + size_t offset = 0; + + for (size_t cnt = 0; slotinfo[cnt].map != NULL; ++cnt) + { + assert (cnt < GL(dl_tls_dtv_slotinfo_list)->len); + + size_t firstbyte = (-slotinfo[cnt].map->l_tls_firstbyte_offset + & (slotinfo[cnt].map->l_tls_align - 1)); + size_t off; + max_align = MAX (max_align, slotinfo[cnt].map->l_tls_align); + + if (freebottom - freetop >= slotinfo[cnt].map->l_tls_blocksize) + { + off = roundup (freetop + slotinfo[cnt].map->l_tls_blocksize + - firstbyte, slotinfo[cnt].map->l_tls_align) + + firstbyte; + if (off <= freebottom) + { + freetop = off; + + /* XXX For some architectures we perhaps should store the + negative offset. */ + slotinfo[cnt].map->l_tls_offset = off; + continue; + } + } + + off = roundup (offset + slotinfo[cnt].map->l_tls_blocksize - firstbyte, + slotinfo[cnt].map->l_tls_align) + firstbyte; + if (off > offset + slotinfo[cnt].map->l_tls_blocksize + + (freebottom - freetop)) + { + freetop = offset; + freebottom = off - slotinfo[cnt].map->l_tls_blocksize; + } + offset = off; + + /* XXX For some architectures we perhaps should store the + negative offset. */ + slotinfo[cnt].map->l_tls_offset = off; + } + + GL(dl_tls_static_used) = offset; + GL(dl_tls_static_size) = (roundup (offset + TLS_STATIC_SURPLUS, max_align) + + TLS_TCB_SIZE); +#elif TLS_DTV_AT_TP + /* The TLS blocks start right after the TCB. */ + size_t offset = TLS_TCB_SIZE; + + for (size_t cnt = 0; slotinfo[cnt].map != NULL; ++cnt) + { + assert (cnt < GL(dl_tls_dtv_slotinfo_list)->len); + + size_t firstbyte = (-slotinfo[cnt].map->l_tls_firstbyte_offset + & (slotinfo[cnt].map->l_tls_align - 1)); + size_t off; + max_align = MAX (max_align, slotinfo[cnt].map->l_tls_align); + + if (slotinfo[cnt].map->l_tls_blocksize <= freetop - freebottom) + { + off = roundup (freebottom, slotinfo[cnt].map->l_tls_align); + if (off - freebottom < firstbyte) + off += slotinfo[cnt].map->l_tls_align; + if (off + slotinfo[cnt].map->l_tls_blocksize - firstbyte <= freetop) + { + slotinfo[cnt].map->l_tls_offset = off - firstbyte; + freebottom = (off + slotinfo[cnt].map->l_tls_blocksize + - firstbyte); + continue; + } + } + + off = roundup (offset, slotinfo[cnt].map->l_tls_align); + if (off - offset < firstbyte) + off += slotinfo[cnt].map->l_tls_align; + + slotinfo[cnt].map->l_tls_offset = off - firstbyte; + if (off - firstbyte - offset > freetop - freebottom) + { + freebottom = offset; + freetop = off - firstbyte; + } + + offset = off + slotinfo[cnt].map->l_tls_blocksize - firstbyte; + } + + GL(dl_tls_static_used) = offset; + GL(dl_tls_static_size) = roundup (offset + TLS_STATIC_SURPLUS, + TLS_TCB_ALIGN); +#else +# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" +#endif + + /* The alignment requirement for the static TLS block. */ + GL(dl_tls_static_align) = max_align; +} +#endif /* SHARED */ + +static void * +internal_function +allocate_dtv (void *result) +{ + dtv_t *dtv; + size_t dtv_length; + + /* We allocate a few more elements in the dtv than are needed for the + 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)); + if (dtv != NULL) + { + /* This is the initial length of the dtv. */ + dtv[0].counter = dtv_length; + + /* The rest of the dtv (including the generation counter) is + Initialize with zero to indicate nothing there. */ + + /* Add the dtv to the thread data structures. */ + INSTALL_DTV (result, dtv); + } + else + result = NULL; + + return result; +} + + +/* Get size and alignment requirements of the static TLS block. */ +void +internal_function +_dl_get_tls_static_info (size_t *sizep, size_t *alignp) +{ + *sizep = GL(dl_tls_static_size); + *alignp = GL(dl_tls_static_align); +} + +/* Derive the location of the pointer to the start of the original + allocation (before alignment) from the pointer to the TCB. */ +static inline void ** +tcb_to_pointer_to_free_location (void *tcb) +{ +#if TLS_TCB_AT_TP + /* The TCB follows the TLS blocks, and the pointer to the front + follows the TCB. */ + void **original_pointer_location = tcb + TLS_TCB_SIZE; +#elif TLS_DTV_AT_TP + /* The TCB comes first, preceded by the pre-TCB, and the pointer is + before that. */ + void **original_pointer_location = tcb - TLS_PRE_TCB_SIZE - sizeof (void *); +#endif + return original_pointer_location; +} + +void * +internal_function +_dl_allocate_tls_storage (void) +{ + void *result; + size_t size = GL(dl_tls_static_size); + +#if TLS_DTV_AT_TP + /* Memory layout is: + [ TLS_PRE_TCB_SIZE ] [ TLS_TCB_SIZE ] [ TLS blocks ] + ^ This should be returned. */ + size += TLS_PRE_TCB_SIZE; +#endif + + /* Perform the allocation. Reserve space for the required alignment + and the pointer to the original allocation. */ + size_t alignment = GL(dl_tls_static_align); + void *allocated = malloc (size + alignment + sizeof (void *)); + if (__glibc_unlikely (allocated == NULL)) + return NULL; + + /* Perform alignment and allocate the DTV. */ +#if TLS_TCB_AT_TP + /* The TCB follows the TLS blocks, which determine the alignment. + (TCB alignment requirements have been taken into account when + calculating GL(dl_tls_static_align).) */ + void *aligned = (void *) roundup ((uintptr_t) allocated, alignment); + result = aligned + size - TLS_TCB_SIZE; + + /* Clear the TCB data structure. We can't ask the caller (i.e. + libpthread) to do it, because we will initialize the DTV et al. */ + memset (result, '\0', TLS_TCB_SIZE); +#elif TLS_DTV_AT_TP + /* Pre-TCB and TCB come before the TLS blocks. The layout computed + in _dl_determine_tlsoffset assumes that the TCB is aligned to the + TLS block alignment, and not just the TLS blocks after it. This + can leave an unused alignment gap between the TCB and the TLS + blocks. */ + result = (void *) roundup + (sizeof (void *) + TLS_PRE_TCB_SIZE + (uintptr_t) allocated, + alignment); + + /* Clear the TCB data structure and TLS_PRE_TCB_SIZE bytes before + it. We can't ask the caller (i.e. libpthread) to do it, because + we will initialize the DTV et al. */ + memset (result - TLS_PRE_TCB_SIZE, '\0', TLS_PRE_TCB_SIZE + TLS_TCB_SIZE); +#endif + + /* Record the value of the original pointer for later + deallocation. */ + *tcb_to_pointer_to_free_location (result) = allocated; + + result = allocate_dtv (result); + if (result == NULL) + free (allocated); + return result; +} + + +#ifndef SHARED +extern dtv_t _dl_static_dtv[]; +# define _dl_initial_dtv (&_dl_static_dtv[1]) +#endif + +static dtv_t * +_dl_resize_dtv (dtv_t *dtv) +{ + /* Resize the dtv. */ + dtv_t *newp; + /* Load GL(dl_tls_max_dtv_idx) atomically since it may be written to by + other threads concurrently. */ + size_t newsize + = atomic_load_acquire (&GL(dl_tls_max_dtv_idx)) + DTV_SURPLUS; + size_t oldsize = dtv[-1].counter; + + if (dtv == GL(dl_initial_dtv)) + { + /* This is the initial dtv that was either statically allocated in + __libc_setup_tls or allocated during rtld startup using the + dl-minimal.c malloc instead of the real malloc. We can't free + it, we have to abandon the old storage. */ + + newp = malloc ((2 + newsize) * sizeof (dtv_t)); + if (newp == NULL) + oom (); + memcpy (newp, &dtv[-1], (2 + oldsize) * sizeof (dtv_t)); + } + else + { + newp = realloc (&dtv[-1], + (2 + newsize) * sizeof (dtv_t)); + if (newp == NULL) + oom (); + } + + newp[0].counter = newsize; + + /* Clear the newly allocated part. */ + memset (newp + 2 + oldsize, '\0', + (newsize - oldsize) * sizeof (dtv_t)); + + /* Return the generation counter. */ + return &newp[1]; +} + + +void * +internal_function +_dl_allocate_tls_init (void *result) +{ + if (result == NULL) + /* The memory allocation failed. */ + return NULL; + + dtv_t *dtv = GET_DTV (result); + struct dtv_slotinfo_list *listp; + size_t total = 0; + size_t maxgen = 0; + + /* Check if the current dtv is big enough. */ + if (dtv[-1].counter < GL(dl_tls_max_dtv_idx)) + { + /* Resize the dtv. */ + dtv = _dl_resize_dtv (dtv); + + /* Install this new dtv in the thread data structures. */ + INSTALL_DTV (result, &dtv[-1]); + } + + /* We have to prepare the dtv for all currently loaded modules using + TLS. For those which are dynamically loaded we add the values + indicating deferred allocation. */ + listp = GL(dl_tls_dtv_slotinfo_list); + while (1) + { + size_t cnt; + + for (cnt = total == 0 ? 1 : 0; cnt < listp->len; ++cnt) + { + struct link_map *map; + void *dest; + + /* Check for the total number of used slots. */ + if (total + cnt > GL(dl_tls_max_dtv_idx)) + break; + + map = listp->slotinfo[cnt].map; + if (map == NULL) + /* Unused entry. */ + continue; + + /* Keep track of the maximum generation number. This might + not be the generation counter. */ + assert (listp->slotinfo[cnt].gen <= GL(dl_tls_generation)); + maxgen = MAX (maxgen, listp->slotinfo[cnt].gen); + + dtv[map->l_tls_modid].pointer.val = TLS_DTV_UNALLOCATED; + dtv[map->l_tls_modid].pointer.to_free = NULL; + + if (map->l_tls_offset == NO_TLS_OFFSET + || map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET) + continue; + + assert (map->l_tls_modid == total + cnt); + assert (map->l_tls_blocksize >= map->l_tls_initimage_size); +#if TLS_TCB_AT_TP + assert ((size_t) map->l_tls_offset >= map->l_tls_blocksize); + dest = (char *) result - map->l_tls_offset; +#elif TLS_DTV_AT_TP + dest = (char *) result + map->l_tls_offset; +#else +# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" +#endif + + /* Set up the DTV entry. The simplified __tls_get_addr that + some platforms use in static programs requires it. */ + dtv[map->l_tls_modid].pointer.val = dest; + + /* Copy the initialization image and clear the BSS part. */ + memset (__mempcpy (dest, map->l_tls_initimage, + map->l_tls_initimage_size), '\0', + map->l_tls_blocksize - map->l_tls_initimage_size); + } + + total += cnt; + if (total >= GL(dl_tls_max_dtv_idx)) + break; + + listp = listp->next; + assert (listp != NULL); + } + + /* The DTV version is up-to-date now. */ + dtv[0].counter = maxgen; + + return result; +} +rtld_hidden_def (_dl_allocate_tls_init) + +void * +internal_function +_dl_allocate_tls (void *mem) +{ + return _dl_allocate_tls_init (mem == NULL + ? _dl_allocate_tls_storage () + : allocate_dtv (mem)); +} +rtld_hidden_def (_dl_allocate_tls) + + +void +internal_function +_dl_deallocate_tls (void *tcb, bool dealloc_tcb) +{ + dtv_t *dtv = GET_DTV (tcb); + + /* We need to free the memory allocated for non-static TLS. */ + for (size_t cnt = 0; cnt < dtv[-1].counter; ++cnt) + free (dtv[1 + cnt].pointer.to_free); + + /* The array starts with dtv[-1]. */ + if (dtv != GL(dl_initial_dtv)) + free (dtv - 1); + + if (dealloc_tcb) + free (*tcb_to_pointer_to_free_location (tcb)); +} +rtld_hidden_def (_dl_deallocate_tls) + + +#ifdef SHARED +/* The __tls_get_addr function has two basic forms which differ in the + arguments. The IA-64 form takes two parameters, the module ID and + offset. The form used, among others, on IA-32 takes a reference to + a special structure which contain the same information. The second + form seems to be more often used (in the moment) so we default to + it. Users of the IA-64 form have to provide adequate definitions + of the following macros. */ +# ifndef GET_ADDR_ARGS +# define GET_ADDR_ARGS tls_index *ti +# define GET_ADDR_PARAM ti +# endif +# ifndef GET_ADDR_MODULE +# define GET_ADDR_MODULE ti->ti_module +# endif +# ifndef GET_ADDR_OFFSET +# define GET_ADDR_OFFSET ti->ti_offset +# endif + +/* Allocate one DTV entry. */ +static struct dtv_pointer +allocate_dtv_entry (size_t alignment, size_t size) +{ + if (powerof2 (alignment) && alignment <= _Alignof (max_align_t)) + { + /* The alignment is supported by malloc. */ + void *ptr = malloc (size); + return (struct dtv_pointer) { ptr, ptr }; + } + + /* Emulate memalign to by manually aligning a pointer returned by + malloc. First compute the size with an overflow check. */ + size_t alloc_size = size + alignment; + if (alloc_size < size) + return (struct dtv_pointer) {}; + + /* Perform the allocation. This is the pointer we need to free + later. */ + void *start = malloc (alloc_size); + if (start == NULL) + return (struct dtv_pointer) {}; + + /* Find the aligned position within the larger allocation. */ + void *aligned = (void *) roundup ((uintptr_t) start, alignment); + + return (struct dtv_pointer) { .val = aligned, .to_free = start }; +} + +static struct dtv_pointer +allocate_and_init (struct link_map *map) +{ + struct dtv_pointer result = allocate_dtv_entry + (map->l_tls_align, map->l_tls_blocksize); + if (result.val == NULL) + oom (); + + /* Initialize the memory. */ + memset (__mempcpy (result.val, map->l_tls_initimage, + map->l_tls_initimage_size), + '\0', map->l_tls_blocksize - map->l_tls_initimage_size); + + return result; +} + + +struct link_map * +_dl_update_slotinfo (unsigned long int req_modid) +{ + struct link_map *the_map = NULL; + dtv_t *dtv = THREAD_DTV (); + + /* The global dl_tls_dtv_slotinfo array contains for each module + index the generation counter current when the entry was created. + This array never shrinks so that all module indices which were + valid at some time can be used to access it. Before the first + use of a new module index in this function the array was extended + appropriately. Access also does not have to be guarded against + modifications of the array. It is assumed that pointer-size + values can be read atomically even in SMP environments. It is + possible that other threads at the same time dynamically load + code and therefore add to the slotinfo list. This is a problem + since we must not pick up any information about incomplete work. + The solution to this is to ignore all dtv slots which were + created after the one we are currently interested. We know that + dynamic loading for this module is completed and this is the last + load operation we know finished. */ + unsigned long int idx = req_modid; + struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list); + + while (idx >= listp->len) + { + idx -= listp->len; + listp = listp->next; + } + + if (dtv[0].counter < listp->slotinfo[idx].gen) + { + /* The generation counter for the slot is higher than what the + current dtv implements. We have to update the whole dtv but + only those entries with a generation counter <= the one for + the entry we need. */ + size_t new_gen = listp->slotinfo[idx].gen; + size_t total = 0; + + /* We have to look through the entire dtv slotinfo list. */ + listp = GL(dl_tls_dtv_slotinfo_list); + do + { + for (size_t cnt = total == 0 ? 1 : 0; cnt < listp->len; ++cnt) + { + size_t gen = listp->slotinfo[cnt].gen; + + if (gen > new_gen) + /* This is a slot for a generation younger than the + one we are handling now. It might be incompletely + set up so ignore it. */ + continue; + + /* If the entry is older than the current dtv layout we + know we don't have to handle it. */ + if (gen <= dtv[0].counter) + continue; + + /* If there is no map this means the entry is empty. */ + struct link_map *map = listp->slotinfo[cnt].map; + if (map == NULL) + { + if (dtv[-1].counter >= total + cnt) + { + /* If this modid was used at some point the memory + might still be allocated. */ + free (dtv[total + cnt].pointer.to_free); + dtv[total + cnt].pointer.val = TLS_DTV_UNALLOCATED; + dtv[total + cnt].pointer.to_free = NULL; + } + + continue; + } + + /* 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) + { + /* Resize the dtv. */ + dtv = _dl_resize_dtv (dtv); + + assert (modid <= dtv[-1].counter); + + /* Install this new dtv in the thread data + structures. */ + INSTALL_NEW_DTV (dtv); + } + + /* If there is currently memory allocate for this + dtv entry free it. */ + /* XXX Ideally we will at some point create a memory + pool. */ + free (dtv[modid].pointer.to_free); + dtv[modid].pointer.val = TLS_DTV_UNALLOCATED; + dtv[modid].pointer.to_free = NULL; + + if (modid == req_modid) + the_map = map; + } + + total += listp->len; + } + while ((listp = listp->next) != NULL); + + /* This will be the new maximum generation counter. */ + dtv[0].counter = new_gen; + } + + return the_map; +} + + +static void * +__attribute_noinline__ +tls_get_addr_tail (GET_ADDR_ARGS, dtv_t *dtv, struct link_map *the_map) +{ + /* The allocation was deferred. Do it now. */ + if (the_map == NULL) + { + /* Find the link map for this module. */ + size_t idx = GET_ADDR_MODULE; + struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list); + + while (idx >= listp->len) + { + idx -= listp->len; + listp = listp->next; + } + + the_map = listp->slotinfo[idx].map; + } + + /* 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 (__glibc_unlikely (the_map->l_tls_offset + != FORCED_DYNAMIC_TLS_OFFSET)) + { + __rtld_lock_lock_recursive (GL(dl_load_lock)); + if (__glibc_likely (the_map->l_tls_offset == NO_TLS_OFFSET)) + { + the_map->l_tls_offset = FORCED_DYNAMIC_TLS_OFFSET; + __rtld_lock_unlock_recursive (GL(dl_load_lock)); + } + else if (__glibc_likely (the_map->l_tls_offset + != FORCED_DYNAMIC_TLS_OFFSET)) + { +#if TLS_TCB_AT_TP + void *p = (char *) THREAD_SELF - the_map->l_tls_offset; +#elif TLS_DTV_AT_TP + void *p = (char *) THREAD_SELF + the_map->l_tls_offset + TLS_PRE_TCB_SIZE; +#else +# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" +#endif + __rtld_lock_unlock_recursive (GL(dl_load_lock)); + + dtv[GET_ADDR_MODULE].pointer.to_free = NULL; + dtv[GET_ADDR_MODULE].pointer.val = p; + + return (char *) p + GET_ADDR_OFFSET; + } + else + __rtld_lock_unlock_recursive (GL(dl_load_lock)); + } + struct dtv_pointer result = allocate_and_init (the_map); + dtv[GET_ADDR_MODULE].pointer = result; + assert (result.to_free != NULL); + + return (char *) result.val + GET_ADDR_OFFSET; +} + + +static struct link_map * +__attribute_noinline__ +update_get_addr (GET_ADDR_ARGS) +{ + struct link_map *the_map = _dl_update_slotinfo (GET_ADDR_MODULE); + dtv_t *dtv = THREAD_DTV (); + + void *p = dtv[GET_ADDR_MODULE].pointer.val; + + if (__glibc_unlikely (p == TLS_DTV_UNALLOCATED)) + return tls_get_addr_tail (GET_ADDR_PARAM, dtv, the_map); + + return (void *) p + GET_ADDR_OFFSET; +} + +/* For all machines that have a non-macro version of __tls_get_addr, we + want to use rtld_hidden_proto/rtld_hidden_def in order to call the + internal alias for __tls_get_addr from ld.so. This avoids a PLT entry + in ld.so for __tls_get_addr. */ + +#ifndef __tls_get_addr +extern void * __tls_get_addr (GET_ADDR_ARGS); +rtld_hidden_proto (__tls_get_addr) +rtld_hidden_def (__tls_get_addr) +#endif + +/* The generic dynamic and local dynamic model cannot be used in + statically linked applications. */ +void * +__tls_get_addr (GET_ADDR_ARGS) +{ + dtv_t *dtv = THREAD_DTV (); + + if (__glibc_unlikely (dtv[0].counter != GL(dl_tls_generation))) + return update_get_addr (GET_ADDR_PARAM); + + void *p = dtv[GET_ADDR_MODULE].pointer.val; + + if (__glibc_unlikely (p == TLS_DTV_UNALLOCATED)) + return tls_get_addr_tail (GET_ADDR_PARAM, dtv, NULL); + + return (char *) p + GET_ADDR_OFFSET; +} +#endif + + +/* Look up the module's TLS block as for __tls_get_addr, + but never touch anything. Return null if it's not allocated yet. */ +void * +_dl_tls_get_addr_soft (struct link_map *l) +{ + if (__glibc_unlikely (l->l_tls_modid == 0)) + /* This module has no TLS segment. */ + return NULL; + + dtv_t *dtv = THREAD_DTV (); + if (__glibc_unlikely (dtv[0].counter != GL(dl_tls_generation))) + { + /* This thread's DTV is not completely current, + but it might already cover this module. */ + + if (l->l_tls_modid >= dtv[-1].counter) + /* Nope. */ + return NULL; + + size_t idx = l->l_tls_modid; + struct dtv_slotinfo_list *listp = GL(dl_tls_dtv_slotinfo_list); + while (idx >= listp->len) + { + idx -= listp->len; + listp = listp->next; + } + + /* We've reached the slot for this module. + If its generation counter is higher than the DTV's, + this thread does not know about this module yet. */ + if (dtv[0].counter < listp->slotinfo[idx].gen) + return NULL; + } + + void *data = dtv[l->l_tls_modid].pointer.val; + if (__glibc_unlikely (data == TLS_DTV_UNALLOCATED)) + /* The DTV is current, but this thread has not yet needed + to allocate this module's segment. */ + data = NULL; + + return data; +} + + +void +_dl_add_to_slotinfo (struct link_map *l) +{ + /* Now that we know the object is loaded successfully add + modules containing TLS data to the dtv info table. We + might have to increase its size. */ + struct dtv_slotinfo_list *listp; + struct dtv_slotinfo_list *prevp; + size_t idx = l->l_tls_modid; + + /* Find the place in the dtv slotinfo list. */ + listp = GL(dl_tls_dtv_slotinfo_list); + prevp = NULL; /* Needed to shut up gcc. */ + do + { + /* Does it fit in the array of this list element? */ + if (idx < listp->len) + break; + idx -= listp->len; + prevp = listp; + listp = listp->next; + } + while (listp != NULL); + + if (listp == NULL) + { + /* When we come here it means we have to add a new element + to the slotinfo list. And the new module must be in + the first slot. */ + assert (idx == 0); + + listp = prevp->next = (struct dtv_slotinfo_list *) + malloc (sizeof (struct dtv_slotinfo_list) + + TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo)); + if (listp == NULL) + { + /* We ran out of memory. We will simply fail this + call but don't undo anything we did so far. The + application will crash or be terminated anyway very + soon. */ + + /* We have to do this since some entries in the dtv + slotinfo array might already point to this + generation. */ + ++GL(dl_tls_generation); + + _dl_signal_error (ENOMEM, "dlopen", NULL, N_("\ +cannot create TLS data structures")); + } + + listp->len = TLS_SLOTINFO_SURPLUS; + listp->next = NULL; + memset (listp->slotinfo, '\0', + TLS_SLOTINFO_SURPLUS * sizeof (struct dtv_slotinfo)); + } + + /* Add the information into the slotinfo data structure. */ + listp->slotinfo[idx].map = l; + listp->slotinfo[idx].gen = GL(dl_tls_generation) + 1; +} |