diff options
Diffstat (limited to 'sysdeps/generic/dl-tls.c')
| -rw-r--r-- | sysdeps/generic/dl-tls.c | 713 |
1 files changed, 713 insertions, 0 deletions
diff --git a/sysdeps/generic/dl-tls.c b/sysdeps/generic/dl-tls.c new file mode 100644 index 0000000000..3382e3493c --- /dev/null +++ b/sysdeps/generic/dl-tls.c @@ -0,0 +1,713 @@ +/* Thread-local storage handling in the ELF dynamic linker. Generic version. + Copyright (C) 2002, 2003, 2004 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <assert.h> +#include <signal.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/param.h> + +#include <tls.h> + +/* We don't need any of this if TLS is not supported. */ +#ifdef USE_TLS + +# 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 + +/* Value used for dtv entries for which the allocation is delayed. */ +# define TLS_DTV_UNALLOCATED ((void *) -1l) + + +/* Out-of-memory handler. */ +# ifdef SHARED +static void +__attribute__ ((__noreturn__)) +oom (void) +{ + _dl_fatal_printf ("cannot allocate memory for thread-local data: ABORT\n"); +} +# endif + + + +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. */ + result = GL(dl_tls_static_nelem) + 1; + /* If the following would not be true we mustn't have assumed + there is a gap. */ + assert (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)); + + /* 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; +} + +# ifdef SHARED + +void +internal_function +_dl_determine_tlsoffset (void) +{ + struct dtv_slotinfo *slotinfo; + size_t max_align = TLS_TCB_ALIGN; + size_t offset, freetop = 0, freebottom = 0; + size_t cnt; + + /* 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); + + 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. */ + offset = 0; + + for (cnt = 1; 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. */ + offset = TLS_TCB_SIZE; + + for (cnt = 1; 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; +} + + +/* This is called only when the data structure setup was skipped at startup, + when there was no need for it then. Now we have dynamically loaded + something needing TLS, or libpthread needs it. */ +int +internal_function +_dl_tls_setup (void) +{ + assert (GL(dl_tls_dtv_slotinfo_list) == NULL); + assert (GL(dl_tls_max_dtv_idx) == 0); + + const size_t nelem = 2 + TLS_SLOTINFO_SURPLUS; + + GL(dl_tls_dtv_slotinfo_list) + = calloc (1, (sizeof (struct dtv_slotinfo_list) + + nelem * sizeof (struct dtv_slotinfo))); + if (GL(dl_tls_dtv_slotinfo_list) == NULL) + return -1; + + GL(dl_tls_dtv_slotinfo_list)->len = nelem; + + /* Number of elements in the static TLS block. It can't be zero + because of various assumptions. The one element is null. */ + GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx) = 1; + + /* This initializes more variables for us. */ + _dl_determine_tlsoffset (); + + return 0; +} +rtld_hidden_def (_dl_tls_setup) +# endif + +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); +} + + +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 + GL(dl_tls_static_align) - 1) + & ~(GL(dl_tls_static_align) - 1); +# endif + + /* Allocate a correctly aligned chunk of memory. */ + result = __libc_memalign (GL(dl_tls_static_align), size); + if (__builtin_expect (result != NULL, 1)) + { + /* Allocate the DTV. */ + void *allocated = result; + +# if TLS_TCB_AT_TP + /* The TCB follows the TLS blocks. */ + result = (char *) result + 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 + result = (char *) result + size - GL(dl_tls_static_size); + + /* 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 ((char *) result - TLS_PRE_TCB_SIZE, 0, + TLS_PRE_TCB_SIZE + TLS_TCB_SIZE); +# endif + + result = allocate_dtv (result); + if (result == NULL) + free (allocated); + } + + return result; +} + + +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; + + /* We have to look 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; + + if (map->l_tls_offset == NO_TLS_OFFSET) + { + /* For dynamically loaded modules we simply store + the value indicating deferred allocation. */ + dtv[map->l_tls_modid].pointer = TLS_DTV_UNALLOCATED; + continue; + } + + assert (map->l_tls_modid == 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 + + /* Copy the initialization image and clear the BSS part. */ + dtv[map->l_tls_modid].pointer = dest; + 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); + } + + 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); + + /* The array starts with dtv[-1]. */ +#ifdef SHARED + if (dtv != GL(dl_initial_dtv)) +#endif + free (dtv - 1); + + if (dealloc_tcb) + { +# if TLS_TCB_AT_TP + /* The TCB follows the TLS blocks. Back up to free the whole block. */ + tcb -= GL(dl_tls_static_size) - TLS_TCB_SIZE; +# elif TLS_DTV_AT_TP + /* Back up the TLS_PRE_TCB_SIZE bytes. */ + tcb -= (TLS_PRE_TCB_SIZE + GL(dl_tls_static_align) - 1) + & ~(GL(dl_tls_static_align) - 1); +# endif + free (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 +# 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 + + +static void * +allocate_and_init (struct link_map *map) +{ + void *newp; + + newp = __libc_memalign (map->l_tls_align, map->l_tls_blocksize); + if (newp == NULL) + oom (); + + /* Initialize the memory. */ + memset (__mempcpy (newp, map->l_tls_initimage, map->l_tls_initimage_size), + '\0', map->l_tls_blocksize - map->l_tls_initimage_size); + + return newp; +} + + +/* 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 (); + struct link_map *the_map = NULL; + void *p; + + if (__builtin_expect (dtv[0].counter != GL(dl_tls_generation), 0)) + { + struct dtv_slotinfo_list *listp; + size_t idx; + + /* 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. */ + idx = GET_ADDR_MODULE; + 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 + { + size_t cnt; + + for (cnt = total = 0 ? 1 : 0; cnt < listp->len; ++cnt) + { + size_t gen = listp->slotinfo[cnt].gen; + struct link_map *map; + size_t modid; + + 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. */ + 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 != TLS_DTV_UNALLOCATED) + { + free (dtv[total + cnt].pointer); + dtv[total + cnt].pointer = TLS_DTV_UNALLOCATED; + } + + continue; + } + + /* Check whether the current dtv array is large enough. */ + modid = map->l_tls_modid; + assert (total + cnt == modid); + if (dtv[-1].counter < modid) + { + /* Reallocate the dtv. */ + dtv_t *newp; + size_t newsize = GL(dl_tls_max_dtv_idx) + DTV_SURPLUS; + size_t oldsize = dtv[-1].counter; + + assert (map->l_tls_modid <= newsize); + + if (dtv == GL(dl_initial_dtv)) + { + /* 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 + free it, we have to abandon the old storage. */ + + newp = malloc ((2 + newsize) * sizeof (dtv_t)); + if (newp == NULL) + oom (); + memcpy (newp, &dtv[-1], 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)); + + /* Point dtv to the generation counter. */ + dtv = &newp[1]; + + /* 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. */ + if (dtv[modid].pointer != TLS_DTV_UNALLOCATED) + /* Note that free is called for NULL is well. We + 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); + + /* This module is loaded dynamically- We defer + memory allocation. */ + dtv[modid].pointer = TLS_DTV_UNALLOCATED; + + if (modid == GET_ADDR_MODULE) + the_map = map; + } + + total += listp->len; + } + while ((listp = listp->next) != NULL); + + /* This will be the new maximum generation counter. */ + dtv[0].counter = new_gen; + } + } + + p = dtv[GET_ADDR_MODULE].pointer; + + if (__builtin_expect (p == TLS_DTV_UNALLOCATED, 0)) + { + /* 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; + } + + p = dtv[GET_ADDR_MODULE].pointer = allocate_and_init (the_map); + } + + return (char *) p + GET_ADDR_OFFSET; +} +# endif + +#endif /* use TLS */ |