[v3,23/37] nptl: Move part of TCB initialization from libpthread to __tls_init_tp
Commit Message
This initalization should only happen once for the main thread's TCB.
At present, auditors can achieve this by not linking against
libpthread. If libpthread becomes part of libc, doing this
initialization in libc would happen for every audit namespace,
or too late (if it happens from the main libc only). That's why
moving this code into ld.so seems the right thing to do, right after
the TCB initialization.
For !__ASSUME_SET_ROBUST_LIST ports, this also moves the symbol
__set_robust_list_avail into ld.so, as __nptl_set_robust_list_avail.
It also turned into a proper boolean flag.
Inline the __pthread_initialize_pids function because it seems no
longer useful as a separate function.
---
nptl/Versions | 6 +++++
nptl/nptl-init.c | 36 ++-----------------------
nptl/pthread-pids.h | 29 --------------------
nptl/pthreadP.h | 6 +++--
nptl/pthread_create.c | 4 +--
nptl/pthread_mutex_init.c | 2 +-
sysdeps/nptl/dl-tls_init_tp.c | 37 ++++++++++++++++++++++++++
sysdeps/unix/sysv/linux/pthread-pids.h | 29 --------------------
8 files changed, 52 insertions(+), 97 deletions(-)
delete mode 100644 nptl/pthread-pids.h
delete mode 100644 sysdeps/unix/sysv/linux/pthread-pids.h
Comments
On 16/03/2021 14:30, Florian Weimer via Libc-alpha wrote:
> This initalization should only happen once for the main thread's TCB.
> At present, auditors can achieve this by not linking against
> libpthread. If libpthread becomes part of libc, doing this
> initialization in libc would happen for every audit namespace,
> or too late (if it happens from the main libc only). That's why
> moving this code into ld.so seems the right thing to do, right after
> the TCB initialization.
Make sense.
>
> For !__ASSUME_SET_ROBUST_LIST ports, this also moves the symbol
> __set_robust_list_avail into ld.so, as __nptl_set_robust_list_avail.
> It also turned into a proper boolean flag.
>
> Inline the __pthread_initialize_pids function because it seems no
> longer useful as a separate function.
LGTM, with just a suggestion below.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> nptl/Versions | 6 +++++
> nptl/nptl-init.c | 36 ++-----------------------
> nptl/pthread-pids.h | 29 --------------------
> nptl/pthreadP.h | 6 +++--
> nptl/pthread_create.c | 4 +--
> nptl/pthread_mutex_init.c | 2 +-
> sysdeps/nptl/dl-tls_init_tp.c | 37 ++++++++++++++++++++++++++
> sysdeps/unix/sysv/linux/pthread-pids.h | 29 --------------------
> 8 files changed, 52 insertions(+), 97 deletions(-)
> delete mode 100644 nptl/pthread-pids.h
> delete mode 100644 sysdeps/unix/sysv/linux/pthread-pids.h
>
> diff --git a/nptl/Versions b/nptl/Versions
> index b619df41fb..c50a5442af 100644
> --- a/nptl/Versions
> +++ b/nptl/Versions
> @@ -417,3 +417,9 @@ libpthread {
> __pthread_initialize_minimal;
> }
> }
> +
> +ld {
> + GLIBC_PRIVATE {
> + __nptl_set_robust_list_avail;
> + }
> +}
> \ No newline at end of file
Ok.
> diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
> index de64e34783..5913bf7272 100644
> --- a/nptl/nptl-init.c
> +++ b/nptl/nptl-init.c
> @@ -36,7 +36,6 @@
> #include <futex-internal.h>
> #include <kernel-features.h>
> #include <libc-pointer-arith.h>
> -#include <pthread-pids.h>
> #include <pthread_mutex_conf.h>
>
> #ifndef TLS_MULTIPLE_THREADS_IN_TCB
> @@ -48,15 +47,6 @@ int *__libc_multiple_threads_ptr attribute_hidden;
> size_t __static_tls_size;
> size_t __static_tls_align_m1;
>
> -#ifndef __ASSUME_SET_ROBUST_LIST
> -/* Negative if we do not have the system call and we can use it. */
> -int __set_robust_list_avail;
> -# define set_robust_list_not_avail() \
> - __set_robust_list_avail = -1
> -#else
> -# define set_robust_list_not_avail() do { } while (0)
> -#endif
> -
> /* Version of the library, used in libthread_db to detect mismatches. */
> static const char nptl_version[] __attribute_used__ = VERSION;
>
> @@ -194,31 +184,9 @@ static bool __nptl_initial_report_events __attribute_used__;
> void
> __pthread_initialize_minimal_internal (void)
> {
> - /* Minimal initialization of the thread descriptor. */
> + /* Partial initialization of the TCB already happened in TLS_INIT_TP
> + and __tls_init_tp. */
> struct pthread *pd = THREAD_SELF;
> - __pthread_initialize_pids (pd);
> - THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
> - THREAD_SETMEM (pd, user_stack, true);
> -
> - /* Initialize the robust mutex data. */
> - {
> -#if __PTHREAD_MUTEX_HAVE_PREV
> - pd->robust_prev = &pd->robust_head;
> -#endif
> - pd->robust_head.list = &pd->robust_head;
> - pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
> - - offsetof (pthread_mutex_t,
> - __data.__list.__next));
> - int res = INTERNAL_SYSCALL_CALL (set_robust_list, &pd->robust_head,
> - sizeof (struct robust_list_head));
> - if (INTERNAL_SYSCALL_ERROR_P (res))
> - set_robust_list_not_avail ();
> - }
> -
> - /* Set initial thread's stack block from 0 up to __libc_stack_end.
> - It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
> - purposes this is good enough. */
> - THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
>
> /* Before initializing GL (dl_stack_user), the debugger could not
> find us and had to set __nptl_initial_report_events. Propagate
Ok.
> diff --git a/nptl/pthread-pids.h b/nptl/pthread-pids.h
> deleted file mode 100644
> index 1a0e9ade41..0000000000
> --- a/nptl/pthread-pids.h
> +++ /dev/null
> @@ -1,29 +0,0 @@
> -/* Initialize pid and tid fields of struct pthread. Stub version.
> - Copyright (C) 2015-2021 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, see
> - <https://www.gnu.org/licenses/>. */
> -
> -#include <pthreadP.h>
> -
> -/* Initialize PD->pid and PD->tid for the initial thread. If there is
> - setup required to arrange that __exit_thread causes PD->tid to be
> - cleared and futex-woken, then this function should do that as well. */
> -static inline void
> -__pthread_initialize_pids (struct pthread *pd)
> -{
> -#error "sysdeps pthread-pids.h file required"
> - pd->pid = pd->tid = -1;
> -}
Ok.
> diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
> index 4b486b3577..68f8ef5aa1 100644
> --- a/nptl/pthreadP.h
> +++ b/nptl/pthreadP.h
> @@ -224,8 +224,10 @@ extern unsigned int __nptl_nthreads;
> libc_hidden_proto (__nptl_nthreads)
>
> #ifndef __ASSUME_SET_ROBUST_LIST
> -/* Negative if we do not have the system call and we can use it. */
> -extern int __set_robust_list_avail attribute_hidden;
> +/* True if the set_robust_list system call works. Initialized in
> + __tls_init_tp. */
> +extern bool __nptl_set_robust_list_avail;
> +rtld_hidden_proto (__nptl_set_robust_list_avail)
> #endif
>
> /* Thread Priority Protection. */
Now that you are touching it, maybe it would be better to move the
__ASSUME_SET_ROBUST_LIST handling only to the dl-tls_init_tp.c and
always define __nptl_set_robust_list_avail (at least one initialization
case)?
> diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
> index 58e10e7741..51340acc4d 100644
> --- a/nptl/pthread_create.c
> +++ b/nptl/pthread_create.c
> @@ -289,7 +289,7 @@ START_THREAD_DEFN
> __ctype_init ();
>
> #ifndef __ASSUME_SET_ROBUST_LIST
> - if (__set_robust_list_avail >= 0)
> + if (__nptl_set_robust_list_avail)
> #endif
> {
> /* This call should never fail because the initial call in init.c
> @@ -439,7 +439,7 @@ START_THREAD_DEFN
> /* We let the kernel do the notification if it is able to do so.
> If we have to do it here there for sure are no PI mutexes involved
> since the kernel support for them is even more recent. */
> - if (__set_robust_list_avail < 0
> + if (!__nptl_set_robust_list_avail
> && __builtin_expect (robust != (void *) &pd->robust_head, 0))
> {
> do
Ok.
> diff --git a/nptl/pthread_mutex_init.c b/nptl/pthread_mutex_init.c
> index 233cebc504..f5c3a4b464 100644
> --- a/nptl/pthread_mutex_init.c
> +++ b/nptl/pthread_mutex_init.c
> @@ -95,7 +95,7 @@ __pthread_mutex_init (pthread_mutex_t *mutex,
> {
> #ifndef __ASSUME_SET_ROBUST_LIST
> if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
> - && __set_robust_list_avail < 0)
> + && !__nptl_set_robust_list_avail)
> return ENOTSUP;
> #endif
>
Ok.
> diff --git a/sysdeps/nptl/dl-tls_init_tp.c b/sysdeps/nptl/dl-tls_init_tp.c
> index 8983808233..c5172b7613 100644
> --- a/sysdeps/nptl/dl-tls_init_tp.c
> +++ b/sysdeps/nptl/dl-tls_init_tp.c
> @@ -16,10 +16,17 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> +#include <kernel-features.h>
> #include <ldsodefs.h>
> #include <list.h>
> +#include <nptl/pthreadP.h>
> #include <tls.h>
>
> +#ifndef __ASSUME_SET_ROBUST_LIST
> +bool __nptl_set_robust_list_avail;
> +rtld_hidden_data_def (__nptl_set_robust_list_avail)
> +#endif
> +
> void
> __tls_init_tp (void)
> {
> @@ -27,4 +34,34 @@ __tls_init_tp (void)
> INIT_LIST_HEAD (&GL (dl_stack_used));
> INIT_LIST_HEAD (&GL (dl_stack_user));
> list_add (&THREAD_SELF->list, &GL (dl_stack_user));
> +
> + /* Early initialization of the TCB. */
> + struct pthread *pd = THREAD_SELF;
> + pd->tid = INTERNAL_SYSCALL_CALL (set_tid_address, &pd->tid);
> + THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
> + THREAD_SETMEM (pd, user_stack, true);
> +
> + /* Initialize the robust mutex data. */
> + {
> +#if __PTHREAD_MUTEX_HAVE_PREV
> + pd->robust_prev = &pd->robust_head;
> +#endif
> + pd->robust_head.list = &pd->robust_head;
> + pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
> + - offsetof (pthread_mutex_t,
> + __data.__list.__next));
> + int res = INTERNAL_SYSCALL_CALL (set_robust_list, &pd->robust_head,
> + sizeof (struct robust_list_head));
> + if (!INTERNAL_SYSCALL_ERROR_P (res))
> + {
> +#ifndef __ASSUME_SET_ROBUST_LIST
> + __nptl_set_robust_list_avail = true;
> +#endif
> + }
> + }
> +
> + /* Set initial thread's stack block from 0 up to __libc_stack_end.
> + It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
> + purposes this is good enough. */
> + THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
> }
Ok.
> diff --git a/sysdeps/unix/sysv/linux/pthread-pids.h b/sysdeps/unix/sysv/linux/pthread-pids.h
> deleted file mode 100644
> index 10b58899f5..0000000000
> --- a/sysdeps/unix/sysv/linux/pthread-pids.h
> +++ /dev/null
> @@ -1,29 +0,0 @@
> -/* Initialize pid and tid fields of struct pthread. Linux version.
> - Copyright (C) 2015-2021 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, see
> - <https://www.gnu.org/licenses/>. */
> -
> -#include <pthreadP.h>
> -#include <sysdep.h>
> -
> -/* Initialize PD->pid and PD->tid for the initial thread. If there is
> - setup required to arrange that __exit_thread causes PD->tid to be
> - cleared and futex-woken, then this function should do that as well. */
> -static inline void
> -__pthread_initialize_pids (struct pthread *pd)
> -{
> - pd->tid = INTERNAL_SYSCALL_CALL (set_tid_address, &pd->tid);
> -}
>
Ok.
* Adhemerval Zanella:
>> diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
>> index 4b486b3577..68f8ef5aa1 100644
>> --- a/nptl/pthreadP.h
>> +++ b/nptl/pthreadP.h
>> @@ -224,8 +224,10 @@ extern unsigned int __nptl_nthreads;
>> libc_hidden_proto (__nptl_nthreads)
>> #ifndef __ASSUME_SET_ROBUST_LIST
>> -/* Negative if we do not have the system call and we can use it. */
>> -extern int __set_robust_list_avail attribute_hidden;
>> +/* True if the set_robust_list system call works. Initialized in
>> + __tls_init_tp. */
>> +extern bool __nptl_set_robust_list_avail;
>> +rtld_hidden_proto (__nptl_set_robust_list_avail)
>> #endif
>> /* Thread Priority Protection. */
>
> Now that you are touching it, maybe it would be better to move the
> __ASSUME_SET_ROBUST_LIST handling only to the dl-tls_init_tp.c and
> always define __nptl_set_robust_list_avail (at least one initialization
> case)?
I would like make this in a separate change because to make it
self-checking, I also need to turn __ASSUME_SET_ROBUST_LIST into an
always-defined macro.
Thanks,
Florian
@@ -417,3 +417,9 @@ libpthread {
__pthread_initialize_minimal;
}
}
+
+ld {
+ GLIBC_PRIVATE {
+ __nptl_set_robust_list_avail;
+ }
+}
\ No newline at end of file
@@ -36,7 +36,6 @@
#include <futex-internal.h>
#include <kernel-features.h>
#include <libc-pointer-arith.h>
-#include <pthread-pids.h>
#include <pthread_mutex_conf.h>
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
@@ -48,15 +47,6 @@ int *__libc_multiple_threads_ptr attribute_hidden;
size_t __static_tls_size;
size_t __static_tls_align_m1;
-#ifndef __ASSUME_SET_ROBUST_LIST
-/* Negative if we do not have the system call and we can use it. */
-int __set_robust_list_avail;
-# define set_robust_list_not_avail() \
- __set_robust_list_avail = -1
-#else
-# define set_robust_list_not_avail() do { } while (0)
-#endif
-
/* Version of the library, used in libthread_db to detect mismatches. */
static const char nptl_version[] __attribute_used__ = VERSION;
@@ -194,31 +184,9 @@ static bool __nptl_initial_report_events __attribute_used__;
void
__pthread_initialize_minimal_internal (void)
{
- /* Minimal initialization of the thread descriptor. */
+ /* Partial initialization of the TCB already happened in TLS_INIT_TP
+ and __tls_init_tp. */
struct pthread *pd = THREAD_SELF;
- __pthread_initialize_pids (pd);
- THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
- THREAD_SETMEM (pd, user_stack, true);
-
- /* Initialize the robust mutex data. */
- {
-#if __PTHREAD_MUTEX_HAVE_PREV
- pd->robust_prev = &pd->robust_head;
-#endif
- pd->robust_head.list = &pd->robust_head;
- pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
- - offsetof (pthread_mutex_t,
- __data.__list.__next));
- int res = INTERNAL_SYSCALL_CALL (set_robust_list, &pd->robust_head,
- sizeof (struct robust_list_head));
- if (INTERNAL_SYSCALL_ERROR_P (res))
- set_robust_list_not_avail ();
- }
-
- /* Set initial thread's stack block from 0 up to __libc_stack_end.
- It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
- purposes this is good enough. */
- THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
/* Before initializing GL (dl_stack_user), the debugger could not
find us and had to set __nptl_initial_report_events. Propagate
deleted file mode 100644
@@ -1,29 +0,0 @@
-/* Initialize pid and tid fields of struct pthread. Stub version.
- Copyright (C) 2015-2021 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, see
- <https://www.gnu.org/licenses/>. */
-
-#include <pthreadP.h>
-
-/* Initialize PD->pid and PD->tid for the initial thread. If there is
- setup required to arrange that __exit_thread causes PD->tid to be
- cleared and futex-woken, then this function should do that as well. */
-static inline void
-__pthread_initialize_pids (struct pthread *pd)
-{
-#error "sysdeps pthread-pids.h file required"
- pd->pid = pd->tid = -1;
-}
@@ -224,8 +224,10 @@ extern unsigned int __nptl_nthreads;
libc_hidden_proto (__nptl_nthreads)
#ifndef __ASSUME_SET_ROBUST_LIST
-/* Negative if we do not have the system call and we can use it. */
-extern int __set_robust_list_avail attribute_hidden;
+/* True if the set_robust_list system call works. Initialized in
+ __tls_init_tp. */
+extern bool __nptl_set_robust_list_avail;
+rtld_hidden_proto (__nptl_set_robust_list_avail)
#endif
/* Thread Priority Protection. */
@@ -289,7 +289,7 @@ START_THREAD_DEFN
__ctype_init ();
#ifndef __ASSUME_SET_ROBUST_LIST
- if (__set_robust_list_avail >= 0)
+ if (__nptl_set_robust_list_avail)
#endif
{
/* This call should never fail because the initial call in init.c
@@ -439,7 +439,7 @@ START_THREAD_DEFN
/* We let the kernel do the notification if it is able to do so.
If we have to do it here there for sure are no PI mutexes involved
since the kernel support for them is even more recent. */
- if (__set_robust_list_avail < 0
+ if (!__nptl_set_robust_list_avail
&& __builtin_expect (robust != (void *) &pd->robust_head, 0))
{
do
@@ -95,7 +95,7 @@ __pthread_mutex_init (pthread_mutex_t *mutex,
{
#ifndef __ASSUME_SET_ROBUST_LIST
if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
- && __set_robust_list_avail < 0)
+ && !__nptl_set_robust_list_avail)
return ENOTSUP;
#endif
@@ -16,10 +16,17 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
+#include <kernel-features.h>
#include <ldsodefs.h>
#include <list.h>
+#include <nptl/pthreadP.h>
#include <tls.h>
+#ifndef __ASSUME_SET_ROBUST_LIST
+bool __nptl_set_robust_list_avail;
+rtld_hidden_data_def (__nptl_set_robust_list_avail)
+#endif
+
void
__tls_init_tp (void)
{
@@ -27,4 +34,34 @@ __tls_init_tp (void)
INIT_LIST_HEAD (&GL (dl_stack_used));
INIT_LIST_HEAD (&GL (dl_stack_user));
list_add (&THREAD_SELF->list, &GL (dl_stack_user));
+
+ /* Early initialization of the TCB. */
+ struct pthread *pd = THREAD_SELF;
+ pd->tid = INTERNAL_SYSCALL_CALL (set_tid_address, &pd->tid);
+ THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
+ THREAD_SETMEM (pd, user_stack, true);
+
+ /* Initialize the robust mutex data. */
+ {
+#if __PTHREAD_MUTEX_HAVE_PREV
+ pd->robust_prev = &pd->robust_head;
+#endif
+ pd->robust_head.list = &pd->robust_head;
+ pd->robust_head.futex_offset = (offsetof (pthread_mutex_t, __data.__lock)
+ - offsetof (pthread_mutex_t,
+ __data.__list.__next));
+ int res = INTERNAL_SYSCALL_CALL (set_robust_list, &pd->robust_head,
+ sizeof (struct robust_list_head));
+ if (!INTERNAL_SYSCALL_ERROR_P (res))
+ {
+#ifndef __ASSUME_SET_ROBUST_LIST
+ __nptl_set_robust_list_avail = true;
+#endif
+ }
+ }
+
+ /* Set initial thread's stack block from 0 up to __libc_stack_end.
+ It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
+ purposes this is good enough. */
+ THREAD_SETMEM (pd, stackblock_size, (size_t) __libc_stack_end);
}
deleted file mode 100644
@@ -1,29 +0,0 @@
-/* Initialize pid and tid fields of struct pthread. Linux version.
- Copyright (C) 2015-2021 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, see
- <https://www.gnu.org/licenses/>. */
-
-#include <pthreadP.h>
-#include <sysdep.h>
-
-/* Initialize PD->pid and PD->tid for the initial thread. If there is
- setup required to arrange that __exit_thread causes PD->tid to be
- cleared and futex-woken, then this function should do that as well. */
-static inline void
-__pthread_initialize_pids (struct pthread *pd)
-{
- pd->tid = INTERNAL_SYSCALL_CALL (set_tid_address, &pd->tid);
-}