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authorRoland McGrath <roland@hack.frob.com>2015-05-20 14:52:05 -0700
committerRoland McGrath <roland@hack.frob.com>2015-05-20 14:52:05 -0700
commit7cea6212785552b73f22af110a71aa77e2333b82 (patch)
tree445b5634c218d5b563c2e16cef50a2d51772ca9d
parent5e2aa9a421cd429e9ef7d169eda7c18a119e9b8c (diff)
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NaCl: Set tid field to a unique value.
-rw-r--r--ChangeLog10
-rw-r--r--nptl/nptl-init.c6
-rw-r--r--nptl/pthread-pids.h29
-rw-r--r--sysdeps/nacl/createthread.c3
-rw-r--r--sysdeps/nacl/pthread-pids.h65
-rw-r--r--sysdeps/unix/sysv/linux/pthread-pids.h30
6 files changed, 139 insertions, 4 deletions
diff --git a/ChangeLog b/ChangeLog
index 180c504..830d362 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,15 @@
2015-05-20 Roland McGrath <roland@hack.frob.com>
+ * sysdeps/nacl/pthread-pids.h: New file.
+ * sysdeps/nacl/createthread.c: Include <pthread-pids.h>.
+ (create_thread): Use __nacl_get_tid to initialize PD->tid.
+
+ * nptl/pthread-pids.h: New file.
+ * sysdeps/unix/sysv/linux/pthread-pids.h: New file.
+ * nptl/nptl-init.c: Include <pthread-pids.h>.
+ (__pthread_initialize_minimal_internal):
+ Call __pthread_initialize_pids instead of set_tid_address syscall.
+
* sysdeps/unix/sysv/linux/usleep.c: Moved to ...
* sysdeps/posix/usleep.c: ... here.
diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index 1ad41c5..5b8d931 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -36,6 +36,7 @@
#include <lowlevellock.h>
#include <kernel-features.h>
#include <libc-internal.h>
+#include <pthread-pids.h>
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
/* Pointer to the corresponding variable in libc. */
@@ -311,10 +312,7 @@ __pthread_initialize_minimal_internal (void)
/* Minimal initialization of the thread descriptor. */
struct pthread *pd = THREAD_SELF;
-#ifdef __NR_set_tid_address
- INTERNAL_SYSCALL_DECL (err);
- pd->pid = pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
-#endif
+ __pthread_initialize_pids (pd);
THREAD_SETMEM (pd, specific[0], &pd->specific_1stblock[0]);
THREAD_SETMEM (pd, user_stack, true);
if (LLL_LOCK_INITIALIZER != 0)
diff --git a/nptl/pthread-pids.h b/nptl/pthread-pids.h
new file mode 100644
index 0000000..33d764c
--- /dev/null
+++ b/nptl/pthread-pids.h
@@ -0,0 +1,29 @@
+/* Initialize pid and tid fields of struct pthread. Stub version.
+ Copyright (C) 2015 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
+ <http://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/sysdeps/nacl/createthread.c b/sysdeps/nacl/createthread.c
index 9df4eae..9d9284a 100644
--- a/sysdeps/nacl/createthread.c
+++ b/sysdeps/nacl/createthread.c
@@ -17,6 +17,7 @@
<http://www.gnu.org/licenses/>. */
#include <nacl-interfaces.h>
+#include <pthread-pids.h>
/* See the comments in pthread_create.c for the requirements for these
two macros and the create_thread function. */
@@ -33,6 +34,8 @@ static int
create_thread (struct pthread *pd, const struct pthread_attr *attr,
bool stopped_start, STACK_VARIABLES_PARMS, bool *thread_ran)
{
+ pd->tid = __nacl_get_tid (pd);
+
pd->stopped_start = stopped_start;
if (__glibc_unlikely (stopped_start))
/* We make sure the thread does not run far by forcing it to get a
diff --git a/sysdeps/nacl/pthread-pids.h b/sysdeps/nacl/pthread-pids.h
new file mode 100644
index 0000000..ccb99d6
--- /dev/null
+++ b/sysdeps/nacl/pthread-pids.h
@@ -0,0 +1,65 @@
+/* Initialize pid and tid fields of struct pthread. NaCl version.
+ Copyright (C) 2015 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <pthreadP.h>
+
+
+/* NaCl has no concept of PID or TID, nor even any notion of an
+ identifier for a thread within the process. But various places in
+ the NPTL implementation rely on using the 'tid' field of the TCB
+ (struct pthread) as an identifier that is unique at least among all
+ live threads in the process. So we must synthesize some number to
+ use. Conveniently, the 'pthread_t' value itself is already unique
+ in exactly this way (because it's the 'struct pthread' pointer).
+
+ The only wrinkle is that 'tid' is a (32-bit) 'int' and its high
+ (sign) bit is used for special purposes, so we must be absolutely
+ sure that we never use a pointer value with the high bit set. (It
+ also cannot be zero, but zero is never a valid pointer anyway.)
+ The NaCl sandbox models for 32-bit machines limit the address space
+ to less than 3GB (in fact, to 1GB), so it's already impossible that
+ a valid pointer will have its high bit set. But the NaCl x86-64
+ sandbox model allows a full 4GB of address space, so we cannot
+ assume that an arbitrary pointer value will not have the high bit
+ set. Conveniently, there are always unused bits in the pointer
+ value for a 'struct pthread', because it is always aligned to at
+ least 32 bits and so the low bits are always zero. Hence, we can
+ safely avoid the danger of a nonzero high bit just by shifting the
+ pointer value right. */
+
+static inline int
+__nacl_get_tid (struct pthread *pd)
+{
+ uintptr_t id = (uintptr_t) pd;
+ int tid = id >> 1;
+ assert ((id & 1) == 0);
+ assert (sizeof id == sizeof tid);
+ assert (tid > 0);
+ return tid;
+}
+
+
+/* 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 = __nacl_get_tid (pd);
+ pd->pid = -1;
+}
diff --git a/sysdeps/unix/sysv/linux/pthread-pids.h b/sysdeps/unix/sysv/linux/pthread-pids.h
new file mode 100644
index 0000000..d333648
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/pthread-pids.h
@@ -0,0 +1,30 @@
+/* Initialize pid and tid fields of struct pthread. Linux version.
+ Copyright (C) 2015 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
+ <http://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)
+{
+ INTERNAL_SYSCALL_DECL (err);
+ pd->pid = pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
+}