Call exit directly in clone (BZ #21512)

On aarch64, alpha, arm, hppa, mips, nios2, powerpc, sh, sparc, tile,
and x86_64 the clone syscall jumps to _exit after the child execution
and the function ends the process execution by calling exit_group.
This behavior have a small issue where threads created with
CLONE_THREAD using clone syscall directly will eventually exit the
whole group altogether instead of just the thread created.  Also,
s390, microblaze, ia64, i386, and m68k differs by calling exit
syscall directly.

This patch changes all architectures to call the exit syscall
directly, as for s390, microblaze, ia64, i386, and m68k.  This do not
have change glibc internal behavior in any sort, since the only
usage of clone implementation in posix_spawn calls _exit directly
in the created child (fork uses a direct call to clone).

Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
powerpc-linux-gnu, powerpc64le-linux-gnu, sparc64-linux-gnu,
and sparcv9-linux-gnu.

	[BZ #21512]
	* sysdeps/unix/sysv/linux/aarch64/clone.S (__clone): Call exit
	syscall instead of jump to _exit.
	(CLONE_VM_BIT): Remove unused define.
	(CLONE_VM): Likewise.
	(CLONE_THREAD_BIT): Likewise.
	(CLONE_THREAD): Likewise.
	* sysdeps/unix/sysv/linux/alpha/clone.S (__clone): Likewise.
	(CLONE_VM): Remove unused define.
	* sysdeps/unix/sysv/linux/arm/clone.S (__clone): Likewise.
	(CLONE_VM): Remove unused define.
	(CLONE_THREAD): Likewise.
	* sysdeps/unix/sysv/linux/i386/clone.S (CLONE_VM): Likewise.
	* sysdeps/unix/sysv/linux/ia64/clone2.S (__clone2): Call exit
	syscall instead of jump to _exit.
	* sysdeps/unix/sysv/linux/hppa/clone.S (__clone): Likewise.
	* sysdeps/unix/sysv/linux/mips/clone.S (__clone): Likewise.
	(CLONE_VM): Remove unused define.
	(CLONE_THREAD): Likewise.
	* sysdeps/unix/sysv/linux/nios2/clone.S (__clone): Likewise.
	(CLONE_VM): Remove unused define.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S (__clone):
	Likewise.
	(CLONE_VM): Remove unused define.
	(CLONE_THREAD): Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S (__clone):
	Likewise.
	(CLONE_VM): Remove unused define.
	(CLONE_THREAD): Likewise.
	* sysdeps/unix/sysv/linux/sh/clone.S  (__clone): Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S (__clone): Likewise.
	(CLONE_VM): Remove unused define.
	* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S (__clone): Likewise.
	(CLONE_VM): Remove unused define.
	* sysdeps/unix/sysv/linux/tile/clone.S (__clone): Likewise.
	* sysdeps/unix/sysv/linux/x86_64/clone.S (__clone): Likewise.
	(CLONE_VM): Remove unused define.
	* sysdeps/unix/sysv/linux/Makefile (tests): Add tst-clone3.
	* sysdeps/unix/sysv/linux/tst-clone3.c: New file.

Fix

1 files changed, 3 insertions, 14 deletions

diff --git a/sysdeps/unix/sysv/linux/nios2/clone.S b/sysdeps/unix/sysv/linux/nios2/clone.S
index 7929dfa..2ba8258 100644
--- a/sysdeps/unix/sysv/linux/nios2/clone.S
+++ b/sysdeps/unix/sysv/linux/nios2/clone.S
@@ -25,8 +25,6 @@
 #include <bits/errno.h>
 #include <tcb-offsets.h>
 
-#define CLONE_VM      0x00000100
-
 /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
 	     void *parent_tidptr, void *tls, void *child_tidptr) */
 
@@ -75,18 +73,9 @@ thread_start:
         /* Call the user's function.  */
 	callr	r5
 
-	/* _exit with the result.  */
-	mov	r4, r2
-#ifdef PIC
-	nextpc	r22
-1:	movhi	r8, %hiadj(_gp_got - 1b)
-	addi	r8, r8, %lo(_gp_got - 1b)
-	add	r22, r22, r8
-	ldw	r8, %call(HIDDEN_JUMPTARGET(_exit))(r22)
-	jmp	r8
-#else
-	jmpi	_exit
-#endif
+	/* exit with the result.  */
+	movi	r2, SYS_ify (exit)
+	trap
 	cfi_endproc
 
 	cfi_startproc