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| author | Alexandre Oliva <aoliva@redhat.com> | 2016-09-21 22:01:16 -0300 |
|---|---|---|
| committer | Alexandre Oliva <aoliva@redhat.com> | 2016-09-21 22:01:16 -0300 |
| commit | 17af5da98cd2c9ec958421ae2108f877e0945451 (patch) | |
| tree | 6f1e45cb0947ef6c28d931f9c07b5a0f1292885c /elf | |
| parent | 444eacba82f675d4657ad55da67b355536be90ab (diff) | |
| download | glibc-17af5da98cd2c9ec958421ae2108f877e0945451.tar.gz | |
[PR19826] fix non-LE TLS in static programs
An earlier fix for TLS dropped early initialization of DTV entries for
modules using static TLS, leaving it for __tls_get_addr to set them
up. That worked on platforms that require the GD access model to be
relaxed to LE in the main executable, but it caused a regression on
platforms that allow GD in the main executable, particularly in
statically-linked programs: they use a custom __tls_get_addr that does
not update the DTV, which fails when the DTV early initialization is
not performed.
In static programs, __libc_setup_tls performs the DTV initialization
for the main thread, but the DTV of other threads is set up in
_dl_allocate_tls_init, so that's the fix that matters.
Restoring the initialization in the remaining functions modified by
this patch was just for uniformity. It's not clear that it is ever
needed: even on platforms that allow GD in the main executable, the
dynamically-linked version of __tls_get_addr would set up the DTV
entries, even for static TLS modules, while updating the DTV counter.
for ChangeLog
[BZ #19826]
* elf/dl-tls.c (_dl_allocate_tls_init): Restore DTV early
initialization of static TLS entries.
* elf/dl-reloc.c (_dl_nothread_init_static_tls): Likewise.
* nptl/allocatestack.c (init_one_static_tls): Likewise.
Diffstat (limited to 'elf')
| -rw-r--r-- | elf/dl-reloc.c | 6 | ||||
| -rw-r--r-- | elf/dl-tls.c | 4 |
2 files changed, 10 insertions, 0 deletions
diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c index 42bddc1e2c..dcab666d56 100644 --- a/elf/dl-reloc.c +++ b/elf/dl-reloc.c @@ -137,6 +137,12 @@ _dl_nothread_init_static_tls (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_t *dtv = THREAD_DTV (); + assert (map->l_tls_modid <= dtv[-1].counter); + dtv[map->l_tls_modid].pointer.to_free = NULL; + dtv[map->l_tls_modid].pointer.val = dest; + /* 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); diff --git a/elf/dl-tls.c b/elf/dl-tls.c index 17567ad1b3..60f4c1da5c 100644 --- a/elf/dl-tls.c +++ b/elf/dl-tls.c @@ -538,6 +538,10 @@ _dl_allocate_tls_init (void *result) # 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', |