Use a Thread Information Block in both single and multi-threaded programs.

This stores errno, the cancelation flags, and related bits for each thread
and is allocated by ld.so or libc.a.  This is an ABI break from 5.9-stable!
Make libpthread dlopen'able by moving the cancelation wrappers into libc
and doing locking and fork/errno handling via callbacks that libpthread
registers when it first initializes.  'errno' *must* be declared via
<errno.h> now!
Clean up libpthread's symbol exports like libc.
On powerpc, offset the TIB/TCB/TLS data from the register per the ELF spec.
Testing by various, particularly sthen@ and patrick@
ok kettenis@

src/include/Makefile

@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile,v 1.210 2016/03/09 16:28:46 deraadt Exp $
+#	$OpenBSD: Makefile,v 1.211 2016/05/07 19:05:21 guenther Exp $
 #	$NetBSD: Makefile,v 1.59 1996/05/15 21:36:43 jtc Exp $
 
 #	@(#)Makefile	5.45.1.1 (Berkeley) 5/6/91
@@ -18,7 +18,7 @@ FILES=	a.out.h ar.h asr.h assert.h bitstring.h blf.h bsd_auth.h \
 	nlist.h nl_types.h paths.h poll.h pwd.h ranlib.h readpassphrase.h \
 	regex.h resolv.h rmd160.h search.h setjmp.h sha1.h sha2.h signal.h \
 	siphash.h sndio.h spawn.h stdbool.h stddef.h stdio.h stdlib.h \
-	string.h strings.h struct.h sysexits.h tar.h tgmath.h time.h \
+	string.h strings.h struct.h sysexits.h tar.h tgmath.h tib.h time.h \
 	ttyent.h unistd.h utime.h utmp.h uuid.h vis.h wchar.h wctype.h
 
 MFILES=	frame.h

src/include/tib.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: tib.h,v 1.2 2016/03/20 02:30:28 guenther Exp $	*/
+/*	$OpenBSD: tib.h,v 1.3 2016/05/07 19:05:21 guenther Exp $	*/
 /*
  * Copyright (c) 2011,2014 Philip Guenther <guenther@openbsd.org>
  *
@@ -46,19 +46,13 @@
  *	TIB_TO_TCB(tib)
  *		Given a TIB pointer, return the matching TCB pointer
  *
- *	TIB_INIT(tib, dtv)
+ *	TIB_INIT(tib, dtv, thread)
  *		Initializes a TIB for a new thread, using the supplied
- *		value for the dtv pointer
- *
- *	TIB_TO_THREAD(tib)
- *		Given a TIB pointer, return a pointer to the struct pthread
+ *		values for its dtv and thread pointers
  *
  *	TIB_GET()
  *		Short-hand for TCB_TO_TIB(TCB_GET())
  *
- *	TIB_THREAD()
- *		Returns a pointer to this thread's struct pthread
- *
  *	TIB_EXTRA_ALIGN
  *		On TLS varaint 2 archs, what alignment is sufficient
  *		for the extra space that will be used for struct pthread?
@@ -66,24 +60,24 @@
  * The following functions are provided by either ld.so (dynamic) or
  * libc (static) for allocating and freeing a common memory block that
  * will hold both the TIB and the pthread structure:
- *	_dl_allocate_tib(sizeof(struct pthread), flags)
+ *	_dl_allocate_tib(sizeof(struct pthread))
  *		Allocates a combined TIB and pthread memory region.
- *		The first argument is the amount of space to reserve
- *		for the pthread structure; the second argument is
- *		either zero or DAT_UPDATE_CURRENT, the latter meaning
- *		this call is to update/replace the current thread's
- *		TIB.  Returns a pointer to the TIB inside the
- *		allocated block.
+ *		The argument is the amount of space to reserve
+ *		for the pthread structure.  Returns a pointer to
+ *		the TIB inside the allocated block.
  *
  * 	_dl_free_tib(tib, sizeof(struct pthread))
  *		Frees a TIB and pthread block previously allocated
- *		with _dl_allocate_tls().  Must be passed the return
+ *		with _dl_allocate_tib().  Must be passed the return
  *		value of that previous call.
  */
 
 /*
  * Regarding <machine/tcb.h>:
  *  - it must define the TLS_VARIANT macro
+ *  - it may define TCB_OFFSET if the TCB address in the kernel and/or
+ *    register is offset from the actual TCB address.  TCB_OFFSET > 0
+ *    means the kernel/register points to *after* the real data.
  *  - if there's a faster way to get or set the TCB pointer for the thread
  *    than the __{get,set}_tcb() syscalls, it should define either or both
  *    the TCB_{GET,SET} macros to do so.
@@ -101,6 +95,23 @@
 #else
 # define TCB_SET(tcb)		__set_tcb(tcb)
 #endif
+#ifndef TCB_OFFSET
+# define TCB_OFFSET	0
+#endif
+
+/*
+ * tib_cantcancel values is non-zero is the thread should skip all
+ * cancellation processing
+ */
+#define CANCEL_DISABLED	1
+#define CANCEL_DYING	2
+
+/*
+ * tib_cancel_point is non-zero if we're in a cancel point; its modified
+ * by the cancel point code and read by the cancellation signal handler
+ */
+#define CANCEL_POINT		1
+#define CANCEL_POINT_DELAYED	2
 
 
 #if TLS_VARIANT == 1
@@ -108,17 +119,16 @@
  * ABI specifies that the static TLS data starts two words after the
  * (notional) thread pointer, with the first of those two words being
  * the TLS dtv pointer.  The other (second) word is reserved for the
- * implementation, so we place the thread's locale there, but we place
- * our thread bits before the TCB, at negative offsets from the
- * TCB pointer.  Ergo, memory is laid out, low to high, as:
+ * implementation, so we place the pointer to the thread structure there,
+ * but we place our actual thread bits before the TCB, at negative offsets
+ * from the TCB pointer.  Ergo, memory is laid out, low to high, as:
  *
  *	[pthread structure]
  *	TIB {
- *		int cancel_flags
- *		int cancel_requested
+ *		...cancelation and other int-sized info...
  *		int errno
  *		void *locale
- *		TCB {
+ *		TCB (- TCB_OFFSET) {
  *			void *dtv
  *			struct pthread *thread
  *		}
@@ -127,21 +137,17 @@
  */
 
 struct tib {
-#ifdef __LP64__
-	int	__tib_padding;		/* padding for 8byte alignment */
-#endif
-	int	tib_cancel_flags;
-	int	tib_cancel;
+	int	tib_thread_flags;	/* internal to libpthread */
+	pid_t	tib_tid;
+	int	tib_cantcancel;
+	int	tib_cancel_point;
+	int	tib_canceled;
 	int	tib_errno;
 	void	*tib_locale;
 	void	*tib_dtv;		/* internal to the runtime linker */
 	void	*tib_thread;
 };
-#ifdef __LP64__
-# define _TIB_PREP(tib)	((void)((tib)->__tib_padding = 0))
-#endif
 
-#define	_TIBO_PTHREAD		(- _ALIGN(sizeof(struct pthread)))
 
 #elif TLS_VARIANT == 2
 /*
@@ -152,15 +158,14 @@ struct tib {
  * out, low to high, as:
  *	static TLS data
  *	TIB {
- *		TCB {
+ *		TCB (- TCB_OFFSET) {
  *			self pointer [i386/amd64 only]
  *			void *dtv
  *		}
  *		struct pthread *thread
  *		void *locale
  *		int errno
- *		int cancel_count_flags
- *		int cancel_requested
+ *		...cancelation and other int-sized info...
  *	}
  *	[pthread structure]
  */
@@ -174,19 +179,20 @@ struct tib {
 	void	*tib_thread;
 	void	*tib_locale;
 	int	tib_errno;
-	int	tib_cancel;		/* set to request cancelation */
-	int	tib_cancel_flags;
-#if defined(__LP64__) || defined(__i386)
+	int	tib_canceled;
+	int	tib_cancel_point;
+	int	tib_cantcancel;
+	pid_t	tib_tid;
+	int	tib_thread_flags;	/* internal to libpthread */
+#if !defined(__LP64__) && !defined(__i386)
 	int	__tib_padding;		/* padding for 8byte alignment */
 #endif
 };
 
-#define	_TIBO_PTHREAD		_ALIGN(sizeof(struct tib))
-
 #if defined(__i386) || defined(__amd64)
 # define _TIB_PREP(tib)	\
-	((void)((tib)->__tib_self = (tib), (tib)->__tib_padding = 0))
-#elif defined(__LP64__)
+	((void)((tib)->__tib_self = (tib)))
+#elif !defined(__LP64__) && !defined(__i386)
 # define _TIB_PREP(tib)	((void)((tib)->__tib_padding = 0))
 #endif
 
@@ -204,8 +210,9 @@ struct tib {
 #define	TIB_INIT(tib, dtv, thread)	do {		\
 		(tib)->tib_thread	= (thread);	\
 		(tib)->tib_locale	= NULL;		\
-		(tib)->tib_cancel_flags	= 0;		\
-		(tib)->tib_cancel	= 0;		\
+		(tib)->tib_cantcancel	= 0;		\
+		(tib)->tib_cancel_point	= 0;		\
+		(tib)->tib_canceled	= 0;		\
 		(tib)->tib_dtv		= (dtv);	\
 		(tib)->tib_errno	= 0;		\
 		_TIB_PREP(tib);				\
@@ -214,13 +221,11 @@ struct tib {
 #ifndef	__tib_tcb
 # define __tib_tcb		tib_dtv
 #endif
-#define	_TIBO_TCB		offsetof(struct tib, __tib_tcb)
+#define	_TIBO_TCB		(offsetof(struct tib, __tib_tcb) + TCB_OFFSET)
 
 #define	TCB_TO_TIB(tcb)		((struct tib *)((char *)(tcb) - _TIBO_TCB))
 #define	TIB_TO_TCB(tib)		((char *)(tib) + _TIBO_TCB)
-#define	TIB_TO_THREAD(tib)	((struct pthread *)(tib)->tib_thread)
 #define	TIB_GET()		TCB_TO_TIB(TCB_GET())
-#define	TCB_THREAD()		TIB_TO_THREAD(TIB_GET())
 
 
 __BEGIN_DECLS