int
internal_function
_dl_tls_setup (void)
{
_dl_assert (_dl_tls_dtv_slotinfo_list == NULL);
_dl_assert (_dl_tls_max_dtv_idx == 0);
const size_t nelem = 2 + TLS_SLOTINFO_SURPLUS;
_dl_tls_dtv_slotinfo_list
= _dl_calloc (1, (sizeof (struct dtv_slotinfo_list)
+ nelem * sizeof (struct dtv_slotinfo)));
if (_dl_tls_dtv_slotinfo_list == NULL)
return -1;
_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. */
_dl_tls_static_nelem = _dl_tls_max_dtv_idx = 1;
/* This initializes more variables for us. */
_dl_determine_tlsoffset ();
return 0;
}
size_t
internal_function
_dl_next_tls_modid (void)
{
size_t result;
if (__builtin_expect (_dl_tls_dtv_gaps, false))
{
size_t disp = 0;
struct dtv_slotinfo_list *runp = _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 = _dl_tls_static_nelem + 1;
if (result <= _dl_tls_max_dtv_idx)
do
{
while (result - disp < runp->len)
{
if (runp->slotinfo[result - disp].map == NULL)
break;
++result;
_dl_assert (result <= _dl_tls_max_dtv_idx + 1);
}
if (result - disp < runp->len)
break;
disp += runp->len;
}
while ((runp = runp->next) != NULL);
if (result > _dl_tls_max_dtv_idx)
{
/* The new index must indeed be exactly one higher than the
previous high. */
_dl_assert (result == _dl_tls_max_dtv_idx + 1);
/* There is no gap anymore. */
_dl_tls_dtv_gaps = false;
goto nogaps;
}
}
else
{
/* No gaps, allocate a new entry. */
nogaps:
result = ++_dl_tls_max_dtv_idx;
}
return result;
}
/*
* We call this function when we have just read an ELF library or executable.
* We add the relevant info to the symbol chain, so that we can resolve all
* externals properly.
*/
struct elf_resolve *_dl_add_elf_hash_table(const char *libname,
DL_LOADADDR_TYPE loadaddr, unsigned long *dynamic_info, unsigned long dynamic_addr,
attribute_unused unsigned long dynamic_size)
{
Elf_Symndx *hash_addr;
struct elf_resolve *tpnt;
int i;
tpnt = _dl_malloc(sizeof(struct elf_resolve));
_dl_memset(tpnt, 0, sizeof(struct elf_resolve));
if (!_dl_loaded_modules)
_dl_loaded_modules = tpnt;
else {
struct elf_resolve *t = _dl_loaded_modules;
while (t->next)
t = t->next;
t->next = tpnt;
t->next->prev = t;
tpnt = t->next;
}
tpnt->next = NULL;
tpnt->init_flag = 0;
tpnt->libname = _dl_strdup(libname);
tpnt->dynamic_addr = (ElfW(Dyn) *)dynamic_addr;
tpnt->libtype = loaded_file;
#ifdef __DSBT__
if (dynamic_info[DT_DSBT_BASE_IDX] != 0)
tpnt->dsbt_table = (void *)dynamic_info[DT_DSBT_BASE_IDX];
if (dynamic_info[DT_DSBT_SIZE_IDX] != 0)
tpnt->dsbt_size = dynamic_info[DT_DSBT_SIZE_IDX];
if (dynamic_info[DT_DSBT_INDEX_IDX] != 0)
tpnt->dsbt_index = dynamic_info[DT_DSBT_INDEX_IDX];
#endif /* __DSBT__ */
#ifdef __LDSO_GNU_HASH_SUPPORT__
if (dynamic_info[DT_GNU_HASH_IDX] != 0) {
Elf32_Word *hash32 = (Elf_Symndx*)dynamic_info[DT_GNU_HASH_IDX];
tpnt->nbucket = *hash32++;
Elf32_Word symbias = *hash32++;
Elf32_Word bitmask_nwords = *hash32++;
/* Must be a power of two. */
_dl_assert ((bitmask_nwords & (bitmask_nwords - 1)) == 0);
tpnt->l_gnu_bitmask_idxbits = bitmask_nwords - 1;
tpnt->l_gnu_shift = *hash32++;
tpnt->l_gnu_bitmask = (ElfW(Addr) *) hash32;
hash32 += __ELF_NATIVE_CLASS / 32 * bitmask_nwords;
tpnt->l_gnu_buckets = hash32;
hash32 += tpnt->nbucket;
tpnt->l_gnu_chain_zero = hash32 - symbias;
} else
internal_function
init_tls (void)
{
/* Number of elements in the static TLS block. */
_dl_tls_static_nelem = _dl_tls_max_dtv_idx;
/* Do not do this twice. The audit interface might have required
the DTV interfaces to be set up early. */
if (_dl_initial_dtv != NULL)
return NULL;
/* Allocate the array which contains the information about the
dtv slots. We allocate a few entries more than needed to
avoid the need for reallocation. */
size_t nelem = _dl_tls_max_dtv_idx + 1 + TLS_SLOTINFO_SURPLUS;
/* Allocate. */
_dl_assert (_dl_tls_dtv_slotinfo_list == NULL);
_dl_tls_dtv_slotinfo_list = (struct dtv_slotinfo_list *)
_dl_calloc (sizeof (struct dtv_slotinfo_list)
+ nelem * sizeof (struct dtv_slotinfo), 1);
/* No need to check the return value. If memory allocation failed
the program would have been terminated. */
struct dtv_slotinfo *slotinfo = _dl_tls_dtv_slotinfo_list->slotinfo;
_dl_tls_dtv_slotinfo_list->len = nelem;
_dl_tls_dtv_slotinfo_list->next = NULL;
/* Fill in the information from the loaded modules. No namespace
but the base one can be filled at this time. */
int i = 0;
struct link_map *l;
for (l = (struct link_map *) _dl_loaded_modules; l != NULL; l = l->l_next)
if (l->l_tls_blocksize != 0)
{
/* This is a module with TLS data. Store the map reference.
The generation counter is zero. */
/* Skeep slot[0]: it will be never used */
slotinfo[++i].map = l;
}
_dl_assert (i == _dl_tls_max_dtv_idx);
/* Compute the TLS offsets for the various blocks. */
_dl_determine_tlsoffset ();
/* Construct the static TLS block and the dtv for the initial
thread. For some platforms this will include allocating memory
for the thread descriptor. The memory for the TLS block will
never be freed. It should be allocated accordingly. The dtv
array can be changed if dynamic loading requires it. */
void *tcbp = _dl_allocate_tls_storage ();
if (tcbp == NULL) {
_dl_debug_early("\ncannot allocate TLS data structures for initial thread");
_dl_exit(30);
}
/* Store for detection of the special case by __tls_get_addr
so it knows not to pass this dtv to the normal realloc. */
_dl_initial_dtv = GET_DTV (tcbp);
/* And finally install it for the main thread. If ld.so itself uses
TLS we know the thread pointer was initialized earlier. */
const char *lossage = TLS_INIT_TP (tcbp, USE___THREAD);
if(__builtin_expect (lossage != NULL, 0)) {
_dl_debug_early("cannot set up thread-local storage: %s\n", lossage);
_dl_exit(30);
}
tls_init_tp_called = true;
return tcbp;
}
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;
_dl_debug_early("Adding to slotinfo for %s\n", l->l_name);
/* Find the place in the dtv slotinfo list. */
listp = _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. */
_dl_assert (idx == 0);
listp = prevp->next = (struct dtv_slotinfo_list *)
_dl_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. */
++_dl_tls_generation;
_dl_dprintf (_dl_debug_file,
"cannot create TLS data structures: ABORT\n");
_dl_exit (127);
}
listp->len = TLS_SLOTINFO_SURPLUS;
listp->next = NULL;
_dl_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 = _dl_tls_generation + 1;
/* ??? ideally this would be done once per call to dlopen. However there's
no easy way to indicate whether a library used TLS, so do it here
instead. */
/* Bump the TLS generation number. */
_dl_tls_generation++;
}
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 = _dl_tls_dtv_slotinfo_list;
_dl_debug_early ("Updating slotinfo for module %d\n", req_modid);
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 = _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;
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 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)
{
_dl_free (dtv[total + cnt].pointer.val);
dtv[total + cnt].pointer.val = TLS_DTV_UNALLOCATED;
}
continue;
}
/* Check whether the current dtv array is large enough. */
size_t modid = map->l_tls_modid;
_dl_assert (total + cnt == modid);
if (dtv[-1].counter < modid)
{
/* Reallocate the dtv. */
dtv_t *newp;
size_t newsize = _dl_tls_max_dtv_idx + DTV_SURPLUS;
size_t oldsize = dtv[-1].counter;
_dl_assert (map->l_tls_modid <= newsize);
if (dtv == _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 = _dl_malloc ((2 + newsize) * sizeof (dtv_t));
if (newp == NULL)
oom ();
_dl_memcpy (newp, &dtv[-1], oldsize * sizeof (dtv_t));
}
else
{
newp = _dl_realloc (&dtv[-1],
(2 + newsize) * sizeof (dtv_t));
if (newp == NULL)
oom ();
}
newp[0].counter = newsize;
/* Clear the newly allocated part. */
_dl_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.is_static
&& dtv[modid].pointer.val != 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. */
_dl_free (dtv[modid].pointer.val);
/* This module is loaded dynamically- We defer memory
allocation. */
dtv[modid].pointer.is_static = false;
dtv[modid].pointer.val = TLS_DTV_UNALLOCATED;
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;
}
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;
/* 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 = _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 > _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. */
maxgen = MAX (maxgen, listp->slotinfo[cnt].gen);
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.val = TLS_DTV_UNALLOCATED;
dtv[map->l_tls_modid].pointer.is_static = false;
continue;
}
_dl_assert (map->l_tls_modid == cnt);
_dl_assert (map->l_tls_blocksize >= map->l_tls_initimage_size);
# ifdef TLS_TCB_AT_TP
_dl_assert ((size_t) map->l_tls_offset >= map->l_tls_blocksize);
dest = (char *) result - map->l_tls_offset;
# elif defined(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.val = dest;
dtv[map->l_tls_modid].pointer.is_static = true;
_dl_memcpy(dest, map->l_tls_initimage, map->l_tls_initimage_size);
_dl_memset((dest + map->l_tls_initimage_size), '\0',
map->l_tls_blocksize - map->l_tls_initimage_size);
}
total += cnt;
if (total >= _dl_tls_max_dtv_idx)
break;
listp = listp->next;
_dl_assert (listp != NULL);
}
/* The DTV version is up-to-date now. */
dtv[0].counter = maxgen;
return result;
}
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. */
_dl_assert (_dl_tls_dtv_slotinfo_list != NULL);
/* There is at this point only one element in the
dl_tls_dtv_slotinfo_list list. */
_dl_assert (_dl_tls_dtv_slotinfo_list->next == NULL);
struct dtv_slotinfo *slotinfo = _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. */
# ifdef TLS_TCB_AT_TP
/* We simply start with zero. */
size_t cnt, offset = 0;
for (cnt = 1; slotinfo[cnt].map != NULL; ++cnt)
{
_dl_assert (cnt < _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_pow2 (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_pow2 (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;
}
_dl_tls_static_used = offset;
_dl_tls_static_size = (roundup_pow2 (offset + TLS_STATIC_SURPLUS, max_align)
+ TLS_TCB_SIZE);
# elif defined(TLS_DTV_AT_TP)
/* The TLS blocks start right after the TCB. */
size_t offset = TLS_TCB_SIZE;
size_t cnt;
for (cnt = 1; slotinfo[cnt].map != NULL; ++cnt)
{
_dl_assert (cnt < _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_pow2 (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_pow2 (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;
}
_dl_tls_static_used = offset;
_dl_tls_static_size = roundup_pow2 (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. */
_dl_tls_static_align = max_align;
}
