[v3] nptl: Export libthread_db-used symbols under GLIBC_PRIVATE
Checks
Commit Message
This allows distributions to strip debugging information from
libc.so.6 without impacting the debugging experience.
---
nptl/Versions | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++
nptl/pthread_create.c | 13 ++++++-----
nptl_db/Makefile | 2 +-
nptl_db/db-symbols.awk | 6 ++++--
4 files changed, 71 insertions(+), 8 deletions(-)
Comments
On 6/28/21 8:41 AM, Florian Weimer wrote:
> This allows distributions to strip debugging information from
> libc.so.6 without impacting the debugging experience.
This looks good, no redundant checks. The only *MAIN* symbol
left in structs.def is from ld.so and we skip checking it
(because the test framework only processes libc.so's symbols).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
> ---
> nptl/Versions | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++
> nptl/pthread_create.c | 13 ++++++-----
> nptl_db/Makefile | 2 +-
> nptl_db/db-symbols.awk | 6 ++++--
> 4 files changed, 71 insertions(+), 8 deletions(-)
>
> diff --git a/nptl/Versions b/nptl/Versions
> index e4fae73c0b..060d8d5dec 100644
> --- a/nptl/Versions
> +++ b/nptl/Versions
> @@ -403,10 +403,14 @@ libc {
> __nptl_deallocate_tsd;
> __nptl_death_event;
> __nptl_free_tcb;
> + __nptl_last_event;
> __nptl_nthreads;
> + __nptl_rtld_global;
> __nptl_setxid_sighandler;
> __nptl_stack_list_add;
> __nptl_stack_list_del;
> + __nptl_threads_events;
> + __nptl_version;
> __pthread_attr_copy;
> __pthread_attr_destroy;
> __pthread_attr_init;
> @@ -430,6 +434,60 @@ libc {
> __pthread_unwind;
> __sched_fifo_max_prio;
> __sched_fifo_min_prio;
> + _thread_db___nptl_last_event;
> + _thread_db___nptl_nthreads;
> + _thread_db___nptl_rtld_global;
> + _thread_db___pthread_keys;
> + _thread_db_const_thread_area;
> + _thread_db_dtv_dtv;
> + _thread_db_dtv_slotinfo_gen;
> + _thread_db_dtv_slotinfo_list_len;
> + _thread_db_dtv_slotinfo_list_next;
> + _thread_db_dtv_slotinfo_list_slotinfo;
> + _thread_db_dtv_slotinfo_map;
> + _thread_db_dtv_t_counter;
> + _thread_db_dtv_t_pointer_val;
> + _thread_db_link_map_l_tls_modid;
> + _thread_db_link_map_l_tls_offset;
> + _thread_db_list_t_next;
> + _thread_db_list_t_prev;
> + _thread_db_pthread_cancelhandling;
> + _thread_db_pthread_dtvp;
> + _thread_db_pthread_eventbuf;
> + _thread_db_pthread_eventbuf_eventmask;
> + _thread_db_pthread_eventbuf_eventmask_event_bits;
> + _thread_db_pthread_key_data_data;
> + _thread_db_pthread_key_data_level2_data;
> + _thread_db_pthread_key_data_seq;
> + _thread_db_pthread_key_struct_destr;
> + _thread_db_pthread_key_struct_seq;
> + _thread_db_pthread_list;
> + _thread_db_pthread_nextevent;
> + _thread_db_pthread_report_events;
> + _thread_db_pthread_schedparam_sched_priority;
> + _thread_db_pthread_schedpolicy;
> + _thread_db_pthread_specific;
> + _thread_db_pthread_start_routine;
> + _thread_db_pthread_tid;
> + _thread_db_register32;
> + _thread_db_register32_thread_area;
> + _thread_db_register64;
> + _thread_db_register64_thread_area;
> + _thread_db_rtld_global__dl_stack_used;
> + _thread_db_rtld_global__dl_stack_user;
> + _thread_db_rtld_global__dl_tls_dtv_slotinfo_list;
> + _thread_db_sizeof_dtv_slotinfo;
> + _thread_db_sizeof_dtv_slotinfo_list;
> + _thread_db_sizeof_list_t;
> + _thread_db_sizeof_pthread;
> + _thread_db_sizeof_pthread_key_data;
> + _thread_db_sizeof_pthread_key_data_level2;
> + _thread_db_sizeof_pthread_key_struct;
> + _thread_db_sizeof_td_eventbuf_t;
> + _thread_db_sizeof_td_thr_events_t;
> + _thread_db_td_eventbuf_t_eventdata;
> + _thread_db_td_eventbuf_t_eventnum;
> + _thread_db_td_thr_events_t_event_bits;
> }
> }
>
> diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
> index 3f017f1e26..d1b6817a81 100644
> --- a/nptl/pthread_create.c
> +++ b/nptl/pthread_create.c
> @@ -43,21 +43,24 @@
>
>
> /* Globally enabled events. */
> -static td_thr_events_t __nptl_threads_events __attribute_used__;
> +td_thr_events_t __nptl_threads_events __attribute__ ((nocommon));
> +libc_hidden_proto (__nptl_threads_events)
> +libc_hidden_data_def (__nptl_threads_events)
>
> /* Pointer to descriptor with the last event. */
> -static struct pthread *__nptl_last_event __attribute_used__;
> +struct pthread *__nptl_last_event __attribute__ ((nocommon));
> +libc_hidden_proto (__nptl_last_event)
> +libc_hidden_data_def (__nptl_last_event)
>
> #ifdef SHARED
> /* This variable is used to access _rtld_global from libthread_db. If
> GDB loads libpthread before ld.so, it is not possible to resolve
> _rtld_global directly during libpthread initialization. */
> -static struct rtld_global *__nptl_rtld_global __attribute_used__
> - = &_rtld_global;
> +struct rtld_global *__nptl_rtld_global = &_rtld_global;
> #endif
>
> /* Version of the library, used in libthread_db to detect mismatches. */
> -static const char nptl_version[] __attribute_used__ = VERSION;
> +const char __nptl_version[] = VERSION;
>
> /* This performs the initialization necessary when going from
> single-threaded to multi-threaded mode for the first time. */
> diff --git a/nptl_db/Makefile b/nptl_db/Makefile
> index 1f79c018a1..c04aa6140a 100644
> --- a/nptl_db/Makefile
> +++ b/nptl_db/Makefile
> @@ -55,7 +55,7 @@ include ../Rules
>
> $(objpfx)db-symbols.out: $(objpfx)db-symbols.v.i \
> $(common-objpfx)libc.so
> - LC_ALL=C $(READELF) -W -s $(filter %.so,$^) | $(AWK) -f $< > $@; \
> + LC_ALL=C $(READELF) -W -D -s $(filter %.so,$^) | $(AWK) -f $< > $@; \
> $(evaluate-test)
>
> $(objpfx)db-symbols.v.i: db-symbols.awk
> diff --git a/nptl_db/db-symbols.awk b/nptl_db/db-symbols.awk
> index ef1d91b167..fe90d3b435 100644
> --- a/nptl_db/db-symbols.awk
> +++ b/nptl_db/db-symbols.awk
> @@ -1,4 +1,4 @@
> -# This script processes the output of 'readelf -W -s' on the libpthread.so
> +# This script processes the output of 'readelf -W -D -s' on the libc.so
> # we've just built. It checks for all the symbols used in td_symbol_list.
>
> BEGIN {
> @@ -12,7 +12,7 @@ BEGIN {
> in_symtab = 0;
> }
>
> -/Symbol table '.symtab'/ { in_symtab=1; next }
> +/Symbol table for image/ { in_symtab=1; next }
> NF == 0 { in_symtab=0; next }
>
> !in_symtab { next }
> @@ -23,6 +23,7 @@ END {
> status = 0;
>
> for (s in required) {
> + s = s "@@GLIBC_PRIVATE"
> if (s in seen) print s, "ok";
> else {
> status = 1;
> @@ -32,6 +33,7 @@ END {
>
> any = "";
> for (s in th_unique) {
> + s = s "@@GLIBC_PRIVATE"
> if (s in seen) {
> any = s;
> break;
>
The 06/28/2021 08:59, Carlos O'Donell via Libc-alpha wrote:
> On 6/28/21 8:41 AM, Florian Weimer wrote:
> > This allows distributions to strip debugging information from
> > libc.so.6 without impacting the debugging experience.
>
> This looks good, no redundant checks. The only *MAIN* symbol
> left in structs.def is from ld.so and we skip checking it
> (because the test framework only processes libc.so's symbols).
>
> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
after the previous two nptl_db commits i see
FAIL: nptl_db/db-symbols
i thought this third patch would fix it, but it didn't:
$ head nptl_db/db-symbols.out
_thread_db_pthread_eventbuf_eventmask_event_bits@@GLIBC_PRIVATE ***MISSING***
_thread_db_pthread_start_routine@@GLIBC_PRIVATE ***MISSING***
_thread_db_sizeof_list_t@@GLIBC_PRIVATE ***MISSING***
_thread_db_pthread_schedparam_sched_priority@@GLIBC_PRIVATE ***MISSING***
_thread_db_td_eventbuf_t_eventdata@@GLIBC_PRIVATE ***MISSING***
_thread_db_list_t_prev@@GLIBC_PRIVATE ***MISSING***
_thread_db_sizeof_dtv_slotinfo@@GLIBC_PRIVATE ***MISSING***
_thread_db_pthread_cancelhandling@@GLIBC_PRIVATE ***MISSING***
_thread_db___pthread_keys@@GLIBC_PRIVATE ***MISSING***
_thread_db_rtld_global__dl_tls_dtv_slotinfo_list@@GLIBC_PRIVATE ***MISSING***
is this expected?
* Szabolcs Nagy:
> The 06/28/2021 08:59, Carlos O'Donell via Libc-alpha wrote:
>> On 6/28/21 8:41 AM, Florian Weimer wrote:
>> > This allows distributions to strip debugging information from
>> > libc.so.6 without impacting the debugging experience.
>>
>> This looks good, no redundant checks. The only *MAIN* symbol
>> left in structs.def is from ld.so and we skip checking it
>> (because the test framework only processes libc.so's symbols).
>>
>> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
>
> after the previous two nptl_db commits i see
>
> FAIL: nptl_db/db-symbols
>
> i thought this third patch would fix it, but it didn't:
>
> $ head nptl_db/db-symbols.out
> _thread_db_pthread_eventbuf_eventmask_event_bits@@GLIBC_PRIVATE ***MISSING***
> _thread_db_pthread_start_routine@@GLIBC_PRIVATE ***MISSING***
> _thread_db_sizeof_list_t@@GLIBC_PRIVATE ***MISSING***
> _thread_db_pthread_schedparam_sched_priority@@GLIBC_PRIVATE ***MISSING***
> _thread_db_td_eventbuf_t_eventdata@@GLIBC_PRIVATE ***MISSING***
> _thread_db_list_t_prev@@GLIBC_PRIVATE ***MISSING***
> _thread_db_sizeof_dtv_slotinfo@@GLIBC_PRIVATE ***MISSING***
> _thread_db_pthread_cancelhandling@@GLIBC_PRIVATE ***MISSING***
> _thread_db___pthread_keys@@GLIBC_PRIVATE ***MISSING***
> _thread_db_rtld_global__dl_tls_dtv_slotinfo_list@@GLIBC_PRIVATE ***MISSING***
>
> is this expected?
It is not expected. The test runs even when cross-compiling, and I
don't see this failure in a default build-many-glibcs.py run.
Are these symbols present as dynamic symbols in your build of libc.so.6?
I suspect your readelf has different output not expected by the script.
Apparently older versions do not print symbol versioning information
with -D -s. 8-( I guess we should parse ELF directly, rather than
readelf output, because it is easier to maintain.
As a stop-gap measure, we should probably switch to objdump -T.
Thanks,
Florian
The 06/29/2021 11:09, Florian Weimer via Libc-alpha wrote:
> * Szabolcs Nagy:
>
> > The 06/28/2021 08:59, Carlos O'Donell via Libc-alpha wrote:
> >> On 6/28/21 8:41 AM, Florian Weimer wrote:
> >> > This allows distributions to strip debugging information from
> >> > libc.so.6 without impacting the debugging experience.
> >>
> >> This looks good, no redundant checks. The only *MAIN* symbol
> >> left in structs.def is from ld.so and we skip checking it
> >> (because the test framework only processes libc.so's symbols).
> >>
> >> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
> >
> > after the previous two nptl_db commits i see
> >
> > FAIL: nptl_db/db-symbols
> >
> > i thought this third patch would fix it, but it didn't:
> >
> > $ head nptl_db/db-symbols.out
> > _thread_db_pthread_eventbuf_eventmask_event_bits@@GLIBC_PRIVATE ***MISSING***
> > _thread_db_pthread_start_routine@@GLIBC_PRIVATE ***MISSING***
> > _thread_db_sizeof_list_t@@GLIBC_PRIVATE ***MISSING***
> > _thread_db_pthread_schedparam_sched_priority@@GLIBC_PRIVATE ***MISSING***
> > _thread_db_td_eventbuf_t_eventdata@@GLIBC_PRIVATE ***MISSING***
> > _thread_db_list_t_prev@@GLIBC_PRIVATE ***MISSING***
> > _thread_db_sizeof_dtv_slotinfo@@GLIBC_PRIVATE ***MISSING***
> > _thread_db_pthread_cancelhandling@@GLIBC_PRIVATE ***MISSING***
> > _thread_db___pthread_keys@@GLIBC_PRIVATE ***MISSING***
> > _thread_db_rtld_global__dl_tls_dtv_slotinfo_list@@GLIBC_PRIVATE ***MISSING***
> >
> > is this expected?
>
> It is not expected. The test runs even when cross-compiling, and I
> don't see this failure in a default build-many-glibcs.py run.
>
> Are these symbols present as dynamic symbols in your build of libc.so.6?
>
> I suspect your readelf has different output not expected by the script.
> Apparently older versions do not print symbol versioning information
> with -D -s. 8-( I guess we should parse ELF directly, rather than
> readelf output, because it is easier to maintain.
>
> As a stop-gap measure, we should probably switch to objdump -T.
yes i can confirm that my readelf does not print symbol versions
with -D -s.
GNU readelf (GNU Binutils for Ubuntu) 2.31.1
i can try to update it if it's considered too old.
* Szabolcs Nagy:
> yes i can confirm that my readelf does not print symbol versions
> with -D -s.
>
> GNU readelf (GNU Binutils for Ubuntu) 2.31.1
>
> i can try to update it if it's considered too old.
It's not too old. I'm going to post a patch that re-uses the abilist
parser, which seems to be really stable.
Thanks,
Florian
@@ -403,10 +403,14 @@ libc {
__nptl_deallocate_tsd;
__nptl_death_event;
__nptl_free_tcb;
+ __nptl_last_event;
__nptl_nthreads;
+ __nptl_rtld_global;
__nptl_setxid_sighandler;
__nptl_stack_list_add;
__nptl_stack_list_del;
+ __nptl_threads_events;
+ __nptl_version;
__pthread_attr_copy;
__pthread_attr_destroy;
__pthread_attr_init;
@@ -430,6 +434,60 @@ libc {
__pthread_unwind;
__sched_fifo_max_prio;
__sched_fifo_min_prio;
+ _thread_db___nptl_last_event;
+ _thread_db___nptl_nthreads;
+ _thread_db___nptl_rtld_global;
+ _thread_db___pthread_keys;
+ _thread_db_const_thread_area;
+ _thread_db_dtv_dtv;
+ _thread_db_dtv_slotinfo_gen;
+ _thread_db_dtv_slotinfo_list_len;
+ _thread_db_dtv_slotinfo_list_next;
+ _thread_db_dtv_slotinfo_list_slotinfo;
+ _thread_db_dtv_slotinfo_map;
+ _thread_db_dtv_t_counter;
+ _thread_db_dtv_t_pointer_val;
+ _thread_db_link_map_l_tls_modid;
+ _thread_db_link_map_l_tls_offset;
+ _thread_db_list_t_next;
+ _thread_db_list_t_prev;
+ _thread_db_pthread_cancelhandling;
+ _thread_db_pthread_dtvp;
+ _thread_db_pthread_eventbuf;
+ _thread_db_pthread_eventbuf_eventmask;
+ _thread_db_pthread_eventbuf_eventmask_event_bits;
+ _thread_db_pthread_key_data_data;
+ _thread_db_pthread_key_data_level2_data;
+ _thread_db_pthread_key_data_seq;
+ _thread_db_pthread_key_struct_destr;
+ _thread_db_pthread_key_struct_seq;
+ _thread_db_pthread_list;
+ _thread_db_pthread_nextevent;
+ _thread_db_pthread_report_events;
+ _thread_db_pthread_schedparam_sched_priority;
+ _thread_db_pthread_schedpolicy;
+ _thread_db_pthread_specific;
+ _thread_db_pthread_start_routine;
+ _thread_db_pthread_tid;
+ _thread_db_register32;
+ _thread_db_register32_thread_area;
+ _thread_db_register64;
+ _thread_db_register64_thread_area;
+ _thread_db_rtld_global__dl_stack_used;
+ _thread_db_rtld_global__dl_stack_user;
+ _thread_db_rtld_global__dl_tls_dtv_slotinfo_list;
+ _thread_db_sizeof_dtv_slotinfo;
+ _thread_db_sizeof_dtv_slotinfo_list;
+ _thread_db_sizeof_list_t;
+ _thread_db_sizeof_pthread;
+ _thread_db_sizeof_pthread_key_data;
+ _thread_db_sizeof_pthread_key_data_level2;
+ _thread_db_sizeof_pthread_key_struct;
+ _thread_db_sizeof_td_eventbuf_t;
+ _thread_db_sizeof_td_thr_events_t;
+ _thread_db_td_eventbuf_t_eventdata;
+ _thread_db_td_eventbuf_t_eventnum;
+ _thread_db_td_thr_events_t_event_bits;
}
}
@@ -43,21 +43,24 @@
/* Globally enabled events. */
-static td_thr_events_t __nptl_threads_events __attribute_used__;
+td_thr_events_t __nptl_threads_events __attribute__ ((nocommon));
+libc_hidden_proto (__nptl_threads_events)
+libc_hidden_data_def (__nptl_threads_events)
/* Pointer to descriptor with the last event. */
-static struct pthread *__nptl_last_event __attribute_used__;
+struct pthread *__nptl_last_event __attribute__ ((nocommon));
+libc_hidden_proto (__nptl_last_event)
+libc_hidden_data_def (__nptl_last_event)
#ifdef SHARED
/* This variable is used to access _rtld_global from libthread_db. If
GDB loads libpthread before ld.so, it is not possible to resolve
_rtld_global directly during libpthread initialization. */
-static struct rtld_global *__nptl_rtld_global __attribute_used__
- = &_rtld_global;
+struct rtld_global *__nptl_rtld_global = &_rtld_global;
#endif
/* Version of the library, used in libthread_db to detect mismatches. */
-static const char nptl_version[] __attribute_used__ = VERSION;
+const char __nptl_version[] = VERSION;
/* This performs the initialization necessary when going from
single-threaded to multi-threaded mode for the first time. */
@@ -55,7 +55,7 @@ include ../Rules
$(objpfx)db-symbols.out: $(objpfx)db-symbols.v.i \
$(common-objpfx)libc.so
- LC_ALL=C $(READELF) -W -s $(filter %.so,$^) | $(AWK) -f $< > $@; \
+ LC_ALL=C $(READELF) -W -D -s $(filter %.so,$^) | $(AWK) -f $< > $@; \
$(evaluate-test)
$(objpfx)db-symbols.v.i: db-symbols.awk
@@ -1,4 +1,4 @@
-# This script processes the output of 'readelf -W -s' on the libpthread.so
+# This script processes the output of 'readelf -W -D -s' on the libc.so
# we've just built. It checks for all the symbols used in td_symbol_list.
BEGIN {
@@ -12,7 +12,7 @@ BEGIN {
in_symtab = 0;
}
-/Symbol table '.symtab'/ { in_symtab=1; next }
+/Symbol table for image/ { in_symtab=1; next }
NF == 0 { in_symtab=0; next }
!in_symtab { next }
@@ -23,6 +23,7 @@ END {
status = 0;
for (s in required) {
+ s = s "@@GLIBC_PRIVATE"
if (s in seen) print s, "ok";
else {
status = 1;
@@ -32,6 +33,7 @@ END {
any = "";
for (s in th_unique) {
+ s = s "@@GLIBC_PRIVATE"
if (s in seen) {
any = s;
break;