[v2] elf: Fix DTV gap reuse logic (BZ #27135)
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Commit Message
This is updated version of the 572bd547d57a (reverted by 40ebfd016ad2)
that fixes the _dl_next_tls_modid issues.
This issue with 572bd547d57a patch is the DTV entry will be only
update on dl_open_worker() with the update_tls_slotinfo() call after
all dependencies are being processed by _dl_map_object_deps(). However
_dl_map_object_deps() itself might call _dl_next_tls_modid(), and since
the _dl_tls_dtv_slotinfo_list::map is not yet set the entry will be
wrongly reused.i
This patch fixes by renaming the _dl_next_tls_modid() function to
_dl_assign_tls_modid() and by passing the link_map so it can set
the slotinfo value so a so subsequente _dl_next_tls_modid() call will
see the entry as allocated.
The intermediary value is cleared up on remove_slotinfo() for the case
a library fails to load with RTLD_NOW.
Checked on x86_64-linux-gnu.
---
elf/Makefile | 64 ++++++++-
elf/dl-close.c | 8 +-
elf/dl-load.c | 2 +-
elf/dl-open.c | 10 --
elf/dl-tls.c | 17 +--
elf/rtld.c | 2 +-
elf/tst-tls20.c | 268 ++++++++++++++++++++++++++++++++++++-
sysdeps/generic/ldsodefs.h | 4 +-
8 files changed, 343 insertions(+), 32 deletions(-)
Comments
The 07/08/2021 13:07, Adhemerval Zanella via Libc-alpha wrote:
> This is updated version of the 572bd547d57a (reverted by 40ebfd016ad2)
> that fixes the _dl_next_tls_modid issues.
>
> This issue with 572bd547d57a patch is the DTV entry will be only
> update on dl_open_worker() with the update_tls_slotinfo() call after
> all dependencies are being processed by _dl_map_object_deps(). However
> _dl_map_object_deps() itself might call _dl_next_tls_modid(), and since
> the _dl_tls_dtv_slotinfo_list::map is not yet set the entry will be
> wrongly reused.i
spurious .i
>
> This patch fixes by renaming the _dl_next_tls_modid() function to
> _dl_assign_tls_modid() and by passing the link_map so it can set
> the slotinfo value so a so subsequente _dl_next_tls_modid() call will
> see the entry as allocated.
.. so a subsequent ..
i think you want to reference the bug number explicitly
to update bugzilla on commit (i think subject line is not
enough) e.g. This patch fixes bug 27135 ..
>
> The intermediary value is cleared up on remove_slotinfo() for the case
> a library fails to load with RTLD_NOW.
>
> Checked on x86_64-linux-gnu.
i have some comments and skipped the tests.
...
> diff --git a/elf/dl-close.c b/elf/dl-close.c
> index 3720e47dd1..f39001cab9 100644
> --- a/elf/dl-close.c
> +++ b/elf/dl-close.c
> @@ -77,8 +77,6 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
> object that wasn't fully set up. */
> if (__glibc_likely (old_map != NULL))
> {
> - assert (old_map->l_tls_modid == idx);
> -
i think this assert should be harmless.
(but not very useful so probably ok to remove:
we should check old_map == imap if anything,
but imap is not available here).
> /* Mark the entry as unused. These can be read concurrently. */
> atomic_store_relaxed (&listp->slotinfo[idx - disp].gen,
> GL(dl_tls_generation) + 1);
> @@ -88,7 +86,11 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
> /* If this is not the last currently used entry no need to look
> further. */
> if (idx != GL(dl_tls_max_dtv_idx))
> - return true;
> + {
> + /* There is an unused dtv entry in the middle. */
> + GL(dl_tls_dtv_gaps) = true;
> + return true;
> + }
OK.
> }
>
> while (idx - disp > (disp == 0 ? 1 + GL(dl_tls_static_nelem) : 0))
> diff --git a/elf/dl-load.c b/elf/dl-load.c
> index a08df001af..650e4edc35 100644
> --- a/elf/dl-load.c
> +++ b/elf/dl-load.c
> @@ -1498,7 +1498,7 @@ cannot enable executable stack as shared object requires");
> not set up TLS data structures, so don't use them now. */
> || __glibc_likely (GL(dl_tls_dtv_slotinfo_list) != NULL)))
> /* Assign the next available module ID. */
> - l->l_tls_modid = _dl_next_tls_modid ();
> + _dl_assign_tls_modid (l);
OK.
>
> #ifdef DL_AFTER_LOAD
> DL_AFTER_LOAD (l);
> diff --git a/elf/dl-open.c b/elf/dl-open.c
> index a066f39bd0..d2240d8747 100644
> --- a/elf/dl-open.c
> +++ b/elf/dl-open.c
> @@ -899,16 +899,6 @@ no more namespaces available for dlmopen()"));
> state if relocation failed, for example. */
> if (args.map)
> {
> - /* Maybe some of the modules which were loaded use TLS.
> - Since it will be removed in the following _dl_close call
> - we have to mark the dtv array as having gaps to fill the
> - holes. This is a pessimistic assumption which won't hurt
> - if not true. There is no need to do this when we are
> - loading the auditing DSOs since TLS has not yet been set
> - up. */
> - if ((mode & __RTLD_AUDIT) == 0)
> - GL(dl_tls_dtv_gaps) = true;
> -
> _dl_close_worker (args.map, true);
OK.
>
> /* All l_nodelete_pending objects should have been deleted
> diff --git a/elf/dl-tls.c b/elf/dl-tls.c
> index 2b5161d10a..6ff94a67af 100644
> --- a/elf/dl-tls.c
> +++ b/elf/dl-tls.c
> @@ -126,8 +126,8 @@ oom (void)
> }
>
>
> -size_t
> -_dl_next_tls_modid (void)
> +void
> +_dl_assign_tls_modid (struct link_map *l)
> {
> size_t result;
>
> @@ -157,7 +157,11 @@ _dl_next_tls_modid (void)
> }
>
> if (result - disp < runp->len)
> - break;
> + {
> + /* Mark the entry as used, so any dependency see it. */
> + runp->slotinfo[result - disp].map = l;
this works, but i'd use relaxed atomic store
since this store can actually be in a data race
with the load in _dl_update_slotinfo.
(i tried to follow the principle in my patchset
that racy access is marked atomic even if it is
benign)
it is also possible to change _dl_update_slotinfo
such that it only reads .map for the given modid
and then there is no race and no atomics is needed
on .map, but that should be done separately.
> + break;
> + }
>
> disp += runp->len;
> }
> @@ -184,17 +188,14 @@ _dl_next_tls_modid (void)
> atomic_store_relaxed (&GL(dl_tls_max_dtv_idx), result);
> }
>
> - return result;
> + l->l_tls_modid = result;
> }
OK.
>
>
> size_t
> _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. */
> + /* The count is the max unless dlclose or failed dlopen created gaps. */
> if (__glibc_likely (!GL(dl_tls_dtv_gaps)))
> return GL(dl_tls_max_dtv_idx);
OK.
>
> diff --git a/elf/rtld.c b/elf/rtld.c
> index fbbd60b446..160faaf5ab 100644
> --- a/elf/rtld.c
> +++ b/elf/rtld.c
> @@ -1722,7 +1722,7 @@ dl_main (const ElfW(Phdr) *phdr,
> /* Add the dynamic linker to the TLS list if it also uses TLS. */
> if (GL(dl_rtld_map).l_tls_blocksize != 0)
> /* Assign a module ID. Do this before loading any audit modules. */
> - GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
> + _dl_assign_tls_modid (&GL(dl_rtld_map));
OK.
>
> audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_AUDIT);
> audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_DEPAUDIT);
...
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 176394de4d..9c15259236 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -1171,8 +1171,8 @@ extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
> extern void _dl_sysdep_start_cleanup (void) attribute_hidden;
>
>
> -/* Determine next available module ID. */
> -extern size_t _dl_next_tls_modid (void) attribute_hidden;
> +/* Determine next available module ID and set the L l_tls_modid. */
> +extern void _dl_assign_tls_modid (struct link_map *l) attribute_hidden;
OK.
>
> /* Count the modules with TLS segments. */
> extern size_t _dl_count_modids (void) attribute_hidden;
> --
> 2.30.2
>
On 09/07/2021 07:26, Szabolcs Nagy wrote:
> The 07/08/2021 13:07, Adhemerval Zanella via Libc-alpha wrote:
>> This is updated version of the 572bd547d57a (reverted by 40ebfd016ad2)
>> that fixes the _dl_next_tls_modid issues.
>>
>> This issue with 572bd547d57a patch is the DTV entry will be only
>> update on dl_open_worker() with the update_tls_slotinfo() call after
>> all dependencies are being processed by _dl_map_object_deps(). However
>> _dl_map_object_deps() itself might call _dl_next_tls_modid(), and since
>> the _dl_tls_dtv_slotinfo_list::map is not yet set the entry will be
>> wrongly reused.i
>
> spurious .i
Ack.
>
>>
>> This patch fixes by renaming the _dl_next_tls_modid() function to
>> _dl_assign_tls_modid() and by passing the link_map so it can set
>> the slotinfo value so a so subsequente _dl_next_tls_modid() call will
>> see the entry as allocated.
>
> .. so a subsequent ..
>
> i think you want to reference the bug number explicitly
> to update bugzilla on commit (i think subject line is not
> enough) e.g. This patch fixes bug 27135 ..
Ok, I will add a new line for v3.
>
>>
>> The intermediary value is cleared up on remove_slotinfo() for the case
>> a library fails to load with RTLD_NOW.
>>
>> Checked on x86_64-linux-gnu.
>
> i have some comments and skipped the tests.
>
> ...
>> diff --git a/elf/dl-close.c b/elf/dl-close.c
>> index 3720e47dd1..f39001cab9 100644
>> --- a/elf/dl-close.c
>> +++ b/elf/dl-close.c
>> @@ -77,8 +77,6 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
>> object that wasn't fully set up. */
>> if (__glibc_likely (old_map != NULL))
>> {
>> - assert (old_map->l_tls_modid == idx);
>> -
>
> i think this assert should be harmless.
>
> (but not very useful so probably ok to remove:
> we should check old_map == imap if anything,
> but imap is not available here).
Yeah, I think I removed while trying to fix it because I recall it
triggered on some testing (although it does not trigger for tst-tls20
currently).
>
>> /* Mark the entry as unused. These can be read concurrently. */
>> atomic_store_relaxed (&listp->slotinfo[idx - disp].gen,
>> GL(dl_tls_generation) + 1);
>> @@ -88,7 +86,11 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
>> /* If this is not the last currently used entry no need to look
>> further. */
>> if (idx != GL(dl_tls_max_dtv_idx))
>> - return true;
>> + {
>> + /* There is an unused dtv entry in the middle. */
>> + GL(dl_tls_dtv_gaps) = true;
>> + return true;
>> + }
>
> OK.
>
>> }
>>
>> while (idx - disp > (disp == 0 ? 1 + GL(dl_tls_static_nelem) : 0))
>> diff --git a/elf/dl-load.c b/elf/dl-load.c
>> index a08df001af..650e4edc35 100644
>> --- a/elf/dl-load.c
>> +++ b/elf/dl-load.c
>> @@ -1498,7 +1498,7 @@ cannot enable executable stack as shared object requires");
>> not set up TLS data structures, so don't use them now. */
>> || __glibc_likely (GL(dl_tls_dtv_slotinfo_list) != NULL)))
>> /* Assign the next available module ID. */
>> - l->l_tls_modid = _dl_next_tls_modid ();
>> + _dl_assign_tls_modid (l);
>
> OK.
>
>>
>> #ifdef DL_AFTER_LOAD
>> DL_AFTER_LOAD (l);
>> diff --git a/elf/dl-open.c b/elf/dl-open.c
>> index a066f39bd0..d2240d8747 100644
>> --- a/elf/dl-open.c
>> +++ b/elf/dl-open.c
>> @@ -899,16 +899,6 @@ no more namespaces available for dlmopen()"));
>> state if relocation failed, for example. */
>> if (args.map)
>> {
>> - /* Maybe some of the modules which were loaded use TLS.
>> - Since it will be removed in the following _dl_close call
>> - we have to mark the dtv array as having gaps to fill the
>> - holes. This is a pessimistic assumption which won't hurt
>> - if not true. There is no need to do this when we are
>> - loading the auditing DSOs since TLS has not yet been set
>> - up. */
>> - if ((mode & __RTLD_AUDIT) == 0)
>> - GL(dl_tls_dtv_gaps) = true;
>> -
>> _dl_close_worker (args.map, true);
>
> OK.
>
>>
>> /* All l_nodelete_pending objects should have been deleted
>> diff --git a/elf/dl-tls.c b/elf/dl-tls.c
>> index 2b5161d10a..6ff94a67af 100644
>> --- a/elf/dl-tls.c
>> +++ b/elf/dl-tls.c
>> @@ -126,8 +126,8 @@ oom (void)
>> }
>>
>>
>> -size_t
>> -_dl_next_tls_modid (void)
>> +void
>> +_dl_assign_tls_modid (struct link_map *l)
>> {
>> size_t result;
>>
>> @@ -157,7 +157,11 @@ _dl_next_tls_modid (void)
>> }
>>
>> if (result - disp < runp->len)
>> - break;
>> + {
>> + /* Mark the entry as used, so any dependency see it. */
>> + runp->slotinfo[result - disp].map = l;
>
> this works, but i'd use relaxed atomic store
> since this store can actually be in a data race
> with the load in _dl_update_slotinfo.
> (i tried to follow the principle in my patchset
> that racy access is marked atomic even if it is
> benign)
>
Ack, it seems reasonable.
> it is also possible to change _dl_update_slotinfo
> such that it only reads .map for the given modid
> and then there is no race and no atomics is needed
> on .map, but that should be done separately.
Agreed.
>
>> + break;
>> + }
>>
>> disp += runp->len;
>> }
>> @@ -184,17 +188,14 @@ _dl_next_tls_modid (void)
>> atomic_store_relaxed (&GL(dl_tls_max_dtv_idx), result);
>> }
>>
>> - return result;
>> + l->l_tls_modid = result;
>> }
>
> OK.
>
>>
>>
>> size_t
>> _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. */
>> + /* The count is the max unless dlclose or failed dlopen created gaps. */
>> if (__glibc_likely (!GL(dl_tls_dtv_gaps)))
>> return GL(dl_tls_max_dtv_idx);
>
> OK.
>
>>
>> diff --git a/elf/rtld.c b/elf/rtld.c
>> index fbbd60b446..160faaf5ab 100644
>> --- a/elf/rtld.c
>> +++ b/elf/rtld.c
>> @@ -1722,7 +1722,7 @@ dl_main (const ElfW(Phdr) *phdr,
>> /* Add the dynamic linker to the TLS list if it also uses TLS. */
>> if (GL(dl_rtld_map).l_tls_blocksize != 0)
>> /* Assign a module ID. Do this before loading any audit modules. */
>> - GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
>> + _dl_assign_tls_modid (&GL(dl_rtld_map));
>
> OK.
>
>>
>> audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_AUDIT);
>> audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_DEPAUDIT);
> ...
>> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
>> index 176394de4d..9c15259236 100644
>> --- a/sysdeps/generic/ldsodefs.h
>> +++ b/sysdeps/generic/ldsodefs.h
>> @@ -1171,8 +1171,8 @@ extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
>> extern void _dl_sysdep_start_cleanup (void) attribute_hidden;
>>
>>
>> -/* Determine next available module ID. */
>> -extern size_t _dl_next_tls_modid (void) attribute_hidden;
>> +/* Determine next available module ID and set the L l_tls_modid. */
>> +extern void _dl_assign_tls_modid (struct link_map *l) attribute_hidden;
>
> OK.
>
>>
>> /* Count the modules with TLS segments. */
>> extern size_t _dl_count_modids (void) attribute_hidden;
>> --
>> 2.30.2
>>
@@ -253,6 +253,13 @@ one-hundred = $(foreach x,0 1 2 3 4 5 6 7 8 9, \
0$x 1$x 2$x 3$x 4$x 5$x 6$x 7$x 8$x 9$x)
tst-tls-many-dynamic-modules := \
$(foreach n,$(one-hundred),tst-tls-manydynamic$(n)mod)
+tst-tls-many-dynamic-modules-dep-suffixes = 0 1 2 3 4 5 6 7 8 9 10 11 12 13 \
+ 14 15 16 17 18 19
+tst-tls-many-dynamic-modules-dep = \
+ $(foreach n,$(tst-tls-many-dynamic-modules-dep-suffixes),tst-tls-manydynamic$(n)mod-dep)
+tst-tls-many-dynamic-modules-dep-bad-suffixes = 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
+tst-tls-many-dynamic-modules-dep-bad = \
+ $(foreach n,$(tst-tls-many-dynamic-modules-dep-bad-suffixes),tst-tls-manydynamic$(n)mod-dep-bad)
extra-test-objs += $(tlsmod17a-modules:=.os) $(tlsmod18a-modules:=.os) \
tst-tlsalign-vars.o
test-extras += tst-tlsmod17a tst-tlsmod18a tst-tlsalign-vars
@@ -325,6 +332,8 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-audit11mod1 tst-audit11mod2 tst-auditmod11 \
tst-audit12mod1 tst-audit12mod2 tst-audit12mod3 tst-auditmod12 \
tst-latepthreadmod $(tst-tls-many-dynamic-modules) \
+ $(tst-tls-many-dynamic-modules-dep) \
+ $(tst-tls-many-dynamic-modules-dep-bad) \
tst-nodelete-dlclose-dso tst-nodelete-dlclose-plugin \
tst-main1mod tst-absolute-sym-lib \
tst-absolute-zero-lib tst-big-note-lib tst-unwind-ctor-lib \
@@ -1812,10 +1821,63 @@ $(objpfx)tst-rtld-help.out: $(objpfx)ld.so
$(evaluate-test)
# Reuses tst-tls-many-dynamic-modules
+$(patsubst %,$(objpfx)%.os,$(tst-tls-many-dynamic-modules-dep)): \
+ $(objpfx)tst-tls-manydynamic%mod-dep.os : tst-tls-manydynamicmod.c
+ $(compile-command.c) \
+ -DNAME=tls_global_$* -DSETTER=set_value_$* -DGETTER=get_value_$*
+$(patsubst %,$(objpfx)%.os,$(tst-tls-many-dynamic-modules-dep-bad)): \
+ $(objpfx)tst-tls-manydynamic%mod-dep-bad.os : tst-tls-manydynamicmod.c
+ $(compile-command.c) \
+ -DNAME=tls_global_$* -DSETTER=set_value_$* -DGETTER=get_value_$*
tst-tls20mod-bad.so-no-z-defs = yes
+# Single dependency.
+$(objpfx)tst-tls-manydynamic0mod-dep.so: $(objpfx)tst-tls-manydynamic1mod-dep.so
+# Double dependencies.
+$(objpfx)tst-tls-manydynamic2mod-dep.so: $(objpfx)tst-tls-manydynamic3mod-dep.so \
+ $(objpfx)tst-tls-manydynamic4mod-dep.so
+# Double dependencies with each dependency depent of another module.
+$(objpfx)tst-tls-manydynamic5mod-dep.so: $(objpfx)tst-tls-manydynamic6mod-dep.so \
+ $(objpfx)tst-tls-manydynamic7mod-dep.so
+$(objpfx)tst-tls-manydynamic6mod-dep.so: $(objpfx)tst-tls-manydynamic8mod-dep.so
+$(objpfx)tst-tls-manydynamic7mod-dep.so: $(objpfx)tst-tls-manydynamic8mod-dep.so
+# Long chain with one double dependency in the middle
+$(objpfx)tst-tls-manydynamic9mod-dep.so: $(objpfx)tst-tls-manydynamic10mod-dep.so \
+ $(objpfx)tst-tls-manydynamic11mod-dep.so
+$(objpfx)tst-tls-manydynamic10mod-dep.so: $(objpfx)tst-tls-manydynamic12mod-dep.so
+$(objpfx)tst-tls-manydynamic12mod-dep.so: $(objpfx)tst-tls-manydynamic13mod-dep.so
+# Long chain with two double depedencies in the middle
+$(objpfx)tst-tls-manydynamic14mod-dep.so: $(objpfx)tst-tls-manydynamic15mod-dep.so
+$(objpfx)tst-tls-manydynamic15mod-dep.so: $(objpfx)tst-tls-manydynamic16mod-dep.so \
+ $(objpfx)tst-tls-manydynamic17mod-dep.so
+$(objpfx)tst-tls-manydynamic16mod-dep.so: $(objpfx)tst-tls-manydynamic18mod-dep.so \
+ $(objpfx)tst-tls-manydynamic19mod-dep.so
+# Same but with an invalid module.
+# Single dependency.
+$(objpfx)tst-tls-manydynamic0mod-dep-bad.so: $(objpfx)tst-tls20mod-bad.so
+# Double dependencies.
+$(objpfx)tst-tls-manydynamic1mod-dep-bad.so: $(objpfx)tst-tls-manydynamic2mod-dep-bad.so \
+ $(objpfx)tst-tls20mod-bad.so
+# Double dependencies with each dependency depent of another module.
+$(objpfx)tst-tls-manydynamic3mod-dep-bad.so: $(objpfx)tst-tls-manydynamic4mod-dep-bad.so \
+ $(objpfx)tst-tls-manydynamic5mod-dep-bad.so
+$(objpfx)tst-tls-manydynamic4mod-dep-bad.so: $(objpfx)tst-tls20mod-bad.so
+$(objpfx)tst-tls-manydynamic5mod-dep-bad.so: $(objpfx)tst-tls20mod-bad.so
+# Long chain with one double dependency in the middle
+$(objpfx)tst-tls-manydynamic6mod-dep-bad.so: $(objpfx)tst-tls-manydynamic7mod-dep-bad.so \
+ $(objpfx)tst-tls-manydynamic8mod-dep-bad.so
+$(objpfx)tst-tls-manydynamic7mod-dep-bad.so: $(objpfx)tst-tls-manydynamic9mod-dep-bad.so
+$(objpfx)tst-tls-manydynamic9mod-dep-bad.so: $(objpfx)tst-tls20mod-bad.so
+# Long chain with two double depedencies in the middle
+$(objpfx)tst-tls-manydynamic10mod-dep-bad.so: $(objpfx)tst-tls-manydynamic11mod-dep-bad.so
+$(objpfx)tst-tls-manydynamic11mod-dep-bad.so: $(objpfx)tst-tls-manydynamic12mod-dep-bad.so \
+ $(objpfx)tst-tls-manydynamic13mod-dep-bad.so
+$(objpfx)tst-tls-manydynamic12mod-dep-bad.so: $(objpfx)tst-tls-manydynamic14mod-dep-bad.so \
+ $(objpfx)tst-tls20mod-bad.so
$(objpfx)tst-tls20: $(shared-thread-library)
$(objpfx)tst-tls20.out: $(objpfx)tst-tls20mod-bad.so \
- $(tst-tls-many-dynamic-modules:%=$(objpfx)%.so)
+ $(tst-tls-many-dynamic-modules:%=$(objpfx)%.so) \
+ $(tst-tls-many-dynamic-modules-dep:%=$(objpfx)%.so) \
+ $(tst-tls-many-dynamic-modules-dep-bad:%=$(objpfx)%.so) \
# Reuses tst-tls-many-dynamic-modules
$(objpfx)tst-tls21: $(shared-thread-library)
@@ -77,8 +77,6 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
object that wasn't fully set up. */
if (__glibc_likely (old_map != NULL))
{
- assert (old_map->l_tls_modid == idx);
-
/* Mark the entry as unused. These can be read concurrently. */
atomic_store_relaxed (&listp->slotinfo[idx - disp].gen,
GL(dl_tls_generation) + 1);
@@ -88,7 +86,11 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
/* If this is not the last currently used entry no need to look
further. */
if (idx != GL(dl_tls_max_dtv_idx))
- return true;
+ {
+ /* There is an unused dtv entry in the middle. */
+ GL(dl_tls_dtv_gaps) = true;
+ return true;
+ }
}
while (idx - disp > (disp == 0 ? 1 + GL(dl_tls_static_nelem) : 0))
@@ -1498,7 +1498,7 @@ cannot enable executable stack as shared object requires");
not set up TLS data structures, so don't use them now. */
|| __glibc_likely (GL(dl_tls_dtv_slotinfo_list) != NULL)))
/* Assign the next available module ID. */
- l->l_tls_modid = _dl_next_tls_modid ();
+ _dl_assign_tls_modid (l);
#ifdef DL_AFTER_LOAD
DL_AFTER_LOAD (l);
@@ -899,16 +899,6 @@ no more namespaces available for dlmopen()"));
state if relocation failed, for example. */
if (args.map)
{
- /* Maybe some of the modules which were loaded use TLS.
- Since it will be removed in the following _dl_close call
- we have to mark the dtv array as having gaps to fill the
- holes. This is a pessimistic assumption which won't hurt
- if not true. There is no need to do this when we are
- loading the auditing DSOs since TLS has not yet been set
- up. */
- if ((mode & __RTLD_AUDIT) == 0)
- GL(dl_tls_dtv_gaps) = true;
-
_dl_close_worker (args.map, true);
/* All l_nodelete_pending objects should have been deleted
@@ -126,8 +126,8 @@ oom (void)
}
-size_t
-_dl_next_tls_modid (void)
+void
+_dl_assign_tls_modid (struct link_map *l)
{
size_t result;
@@ -157,7 +157,11 @@ _dl_next_tls_modid (void)
}
if (result - disp < runp->len)
- break;
+ {
+ /* Mark the entry as used, so any dependency see it. */
+ runp->slotinfo[result - disp].map = l;
+ break;
+ }
disp += runp->len;
}
@@ -184,17 +188,14 @@ _dl_next_tls_modid (void)
atomic_store_relaxed (&GL(dl_tls_max_dtv_idx), result);
}
- return result;
+ l->l_tls_modid = result;
}
size_t
_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. */
+ /* The count is the max unless dlclose or failed dlopen created gaps. */
if (__glibc_likely (!GL(dl_tls_dtv_gaps)))
return GL(dl_tls_max_dtv_idx);
@@ -1722,7 +1722,7 @@ dl_main (const ElfW(Phdr) *phdr,
/* Add the dynamic linker to the TLS list if it also uses TLS. */
if (GL(dl_rtld_map).l_tls_blocksize != 0)
/* Assign a module ID. Do this before loading any audit modules. */
- GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
+ _dl_assign_tls_modid (&GL(dl_rtld_map));
audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_AUDIT);
audit_list_add_dynamic_tag (&state.audit_list, main_map, DT_DEPAUDIT);
@@ -16,6 +16,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <dlfcn.h>
#include <pthread.h>
#include <stdio.h>
@@ -62,25 +63,70 @@ access (int i)
printf ("mod[%d]: &tls = %p\n", i, p);
if (p == NULL)
FAIL_EXIT1 ("dlsym failed: %s\n", dlerror ());
+ TEST_COMPARE (*p, 0);
++*p;
free (buf);
}
+static void
+access_mod (const char *modname, void *mod, int i)
+{
+ char *modsym = xasprintf ("tls_global_%d", i);
+ dlerror ();
+ int *p = dlsym (mod, modsym);
+ printf ("%s: &tls = %p\n", modname, p);
+ if (p == NULL)
+ FAIL_EXIT1 ("dlsym failed: %s\n", dlerror ());
+ TEST_COMPARE (*p, 0);
+ ++*p;
+ free (modsym);
+}
+
+static void
+access_dep (int i)
+{
+ char *modname = xasprintf ("tst-tls-manydynamic%dmod-dep.so", i);
+ void *moddep = xdlopen (modname, RTLD_LAZY);
+ access_mod (modname, moddep, i);
+ free (modname);
+ xdlclose (moddep);
+}
+
+struct start_args
+{
+ const char *modname;
+ void *mod;
+ int modi;
+ int ndeps;
+ const int *deps;
+};
+
static void *
start (void *a)
{
+ struct start_args *args = a;
+
for (int i = 0; i < NMOD; i++)
if (mod[i] != NULL)
access (i);
+
+ if (args != NULL)
+ {
+ access_mod (args->modname, args->mod, args->modi);
+ for (int n = 0; n < args->ndeps; n++)
+ access_dep (args->deps[n]);
+ }
+
return 0;
}
-static int
-do_test (void)
+/* This test gaps with shared libraries with dynamic TLS that has no
+ dependencies. The DTV gap is set with by trying to load an invalid
+ module, the entry should be used on the dlopen. */
+static void
+do_test_no_depedency (void)
{
- int i;
-
- for (i = 0; i < NMOD; i++)
+ for (int i = 0; i < NMOD; i++)
{
load_mod (i);
/* Bump the generation of mod[0] without using new dtv slot. */
@@ -91,8 +137,218 @@ do_test (void)
pthread_t t = xpthread_create (0, start, 0);
xpthread_join (t);
}
- for (i = 0; i < NMOD; i++)
+ for (int i = 0; i < NMOD; i++)
unload_mod (i);
+}
+
+/* The following test check DTV gaps handling with shared libraries that has
+ dependencies. It defines 5 different sets:
+
+ 1. Single dependency:
+ mod0 -> mod1
+ 2. Double dependency:
+ mod2 -> [mod3,mod4]
+ 3. Double dependency with each dependency depent of another module:
+ mod5 -> [mod6,mod7] -> mod8
+ 4. Long chain with one double dependency in the middle:
+ mod9 -> [mod10, mod11] -> mod12 -> mod13
+ 5. Long chain with two double depedencies in the middle:
+ mod15 -> mod15 -> [mod16, mod17]
+ mod15 -> [mod18, mod19]
+
+ This does not cover all the possible gaps and configuration, but it
+ should check if different dynamic shared sets are placed correctly in
+ different gaps configurations. */
+
+static int
+nmodules (uint32_t v)
+{
+ unsigned int r = 0;
+ while (v >>= 1)
+ r++;
+ return r + 1;
+}
+
+static inline bool
+is_mod_set (uint32_t g, uint32_t n)
+{
+ return (1U << (n - 1)) & g;
+}
+
+static void
+print_gap (uint32_t g)
+{
+ printf ("gap: ");
+ int nmods = nmodules (g);
+ for (int n = 1; n <= nmods; n++)
+ printf ("%c", ((1 << (n - 1)) & g) == 0 ? 'G' : 'M');
+ printf ("\n");
+}
+
+static void
+do_test_dependency (void)
+{
+ /* Maps the module and its dependencies, use thread to access the TLS on
+ each loaded module. */
+ static const int tlsmanydeps0[] = { 1 };
+ static const int tlsmanydeps1[] = { 3, 4 };
+ static const int tlsmanydeps2[] = { 6, 7, 8 };
+ static const int tlsmanydeps3[] = { 10, 11, 12 };
+ static const int tlsmanydeps4[] = { 15, 16, 17, 18, 19 };
+ static const struct tlsmanydeps_t
+ {
+ int modi;
+ int ndeps;
+ const int *deps;
+ } tlsmanydeps[] =
+ {
+ { 0, array_length (tlsmanydeps0), tlsmanydeps0 },
+ { 2, array_length (tlsmanydeps1), tlsmanydeps1 },
+ { 5, array_length (tlsmanydeps2), tlsmanydeps2 },
+ { 9, array_length (tlsmanydeps3), tlsmanydeps3 },
+ { 14, array_length (tlsmanydeps4), tlsmanydeps4 },
+ };
+
+ /* The gap configuration is defined as a bitmap: the bit set represents a
+ loaded module prior the tests execution, while a bit unsed is a module
+ unloaded. Not all permtation will show gaps, but it is simpler than
+ define each one independently. */
+ for (uint32_t g = 0; g < 64; g++)
+ {
+ print_gap (g);
+ int nmods = nmodules (g);
+
+ int mods[nmods];
+ /* We use '0' as indication for a gap, to avoid the dlclose on iteration
+ cleanup. */
+ for (int n = 1; n <= nmods; n++)
+ {
+ load_mod (n);
+ mods[n] = n;
+ }
+ for (int n = 1; n <= nmods; n++)
+ {
+ if (!is_mod_set (g, n))
+ {
+ unload_mod (n);
+ mods[n] = 0;
+ }
+ }
+
+ for (int t = 0; t < array_length (tlsmanydeps); t++)
+ {
+ char *moddepname = xasprintf ("tst-tls-manydynamic%dmod-dep.so",
+ tlsmanydeps[t].modi);
+ void *moddep = xdlopen (moddepname, RTLD_LAZY);
+
+ /* Access TLS in all loaded modules. */
+ struct start_args args =
+ {
+ moddepname,
+ moddep,
+ tlsmanydeps[t].modi,
+ tlsmanydeps[t].ndeps,
+ tlsmanydeps[t].deps
+ };
+ pthread_t t = xpthread_create (0, start, &args);
+ xpthread_join (t);
+
+ free (moddepname);
+ xdlclose (moddep);
+ }
+
+ for (int n = 1; n <= nmods; n++)
+ if (mods[n] != 0)
+ unload_mod (n);
+ }
+}
+
+/* The following test check DTV gaps handling with shared libraries that has
+ invalid dependencies. It defines 5 different sets:
+
+ 1. Single dependency:
+ mod0 -> invalid
+ 2. Double dependency:
+ mod1 -> [mod2,invalid]
+ 3. Double dependency with each dependency depent of another module:
+ mod3 -> [mod4,mod5] -> invalid
+ 4. Long chain with one double dependency in the middle:
+ mod6 -> [mod7, mod8] -> mod12 -> invalid
+ 5. Long chain with two double depedencies in the middle:
+ mod10 -> mod11 -> [mod12, mod13]
+ mod12 -> [mod14, invalid]
+
+ This does not cover all the possible gaps and configuration, but it
+ should check if different dynamic shared sets are placed correctly in
+ different gaps configurations. */
+
+static void
+do_test_invalid_dependency (bool bind_now)
+{
+ static const int tlsmanydeps[] = { 0, 1, 3, 6, 10 };
+
+ /* The gap configuration is defined as a bitmap: the bit set represents a
+ loaded module prior the tests execution, while a bit unsed is a module
+ unloaded. Not all permtation will show gaps, but it is simpler than
+ define each one independently. */
+ for (uint32_t g = 0; g < 64; g++)
+ {
+ print_gap (g);
+ int nmods = nmodules (g);
+
+ int mods[nmods];
+ /* We use '0' as indication for a gap, to avoid the dlclose on iteration
+ cleanup. */
+ for (int n = 1; n <= nmods; n++)
+ {
+ load_mod (n);
+ mods[n] = n;
+ }
+ for (int n = 1; n <= nmods; n++)
+ {
+ if (!is_mod_set (g, n))
+ {
+ unload_mod (n);
+ mods[n] = 0;
+ }
+ }
+
+ for (int t = 0; t < array_length (tlsmanydeps); t++)
+ {
+ char *moddepname = xasprintf ("tst-tls-manydynamic%dmod-dep-bad.so",
+ tlsmanydeps[t]);
+ void *moddep;
+ if (bind_now)
+ {
+ moddep = dlopen (moddepname, RTLD_NOW);
+ TEST_VERIFY (moddep == 0);
+ }
+ else
+ moddep = dlopen (moddepname, RTLD_LAZY);
+
+ /* Access TLS in all loaded modules. */
+ pthread_t t = xpthread_create (0, start, NULL);
+ xpthread_join (t);
+
+ free (moddepname);
+ if (!bind_now)
+ xdlclose (moddep);
+ }
+
+ for (int n = 1; n <= nmods; n++)
+ if (mods[n] != 0)
+ unload_mod (n);
+ }
+}
+
+static int
+do_test (void)
+{
+ do_test_no_depedency ();
+ do_test_dependency ();
+ do_test_invalid_dependency (true);
+ do_test_invalid_dependency (false);
+
return 0;
}
@@ -1171,8 +1171,8 @@ extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
extern void _dl_sysdep_start_cleanup (void) attribute_hidden;
-/* Determine next available module ID. */
-extern size_t _dl_next_tls_modid (void) attribute_hidden;
+/* Determine next available module ID and set the L l_tls_modid. */
+extern void _dl_assign_tls_modid (struct link_map *l) attribute_hidden;
/* Count the modules with TLS segments. */
extern size_t _dl_count_modids (void) attribute_hidden;