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[v4,23/37] nptl: Move part of TCB initialization from libpthread to __tls_init_tp

Message ID 5fcef5adf869971854a36d6bca6aa9be6146f08d.1618564630.git.fweimer@redhat.com
State Committed
Commit 442e8a40da9dfa24aeebf4f1a163f0a58b12cf7e
Headers show
Series libpthread: Remove NPTL forwarders | expand

Commit Message

Florian Weimer April 16, 2021, 9:22 a.m. UTC
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.

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
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Patch

diff --git a/nptl/Versions b/nptl/Versions
index 9f1a51c707..2153670c7d 100644
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -372,3 +372,9 @@  libpthread {
     __pthread_initialize_minimal;
   }
 }
+
+ld {
+  GLIBC_PRIVATE {
+     __nptl_set_robust_list_avail;
+  }
+}
\ No newline at end of file
diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index 8f9d41ac62..8d3a9de44d 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -35,7 +35,6 @@ 
 #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
@@ -47,15 +46,6 @@  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;
 
@@ -193,31 +183,9 @@  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
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;
-}
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index 7a3906e2de..b61fda8942 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.  */
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
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
 
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);
 }
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);
-}