[PATCH v3 9/9] aarch64: Consolidate NPTL/non versions of vfork

[Richard Henderson <rth at twiddle dot net>]

From: Richard Henderson <rth@redhat.com>

At the same time, incorporate the 0 -> 0x80000000 mapping
of the pid expected by raise.c.
---
 sysdeps/unix/sysv/linux/aarch64/nptl/pt-vfork.S | 35 ----------------
 sysdeps/unix/sysv/linux/aarch64/pt-vfork.c      | 54 +++++++++++++++++++++++++
 sysdeps/unix/sysv/linux/aarch64/vfork.S         | 29 ++++++++-----
 3 files changed, 74 insertions(+), 44 deletions(-)
 delete mode 100644 sysdeps/unix/sysv/linux/aarch64/nptl/pt-vfork.S
 create mode 100644 sysdeps/unix/sysv/linux/aarch64/pt-vfork.c

diff --git a/sysdeps/unix/sysv/linux/aarch64/nptl/pt-vfork.S b/sysdeps/unix/sysv/linux/aarch64/nptl/pt-vfork.S
deleted file mode 100644
index 2108347..0000000
--- a/sysdeps/unix/sysv/linux/aarch64/nptl/pt-vfork.S
+++ /dev/null
@@ -1,35 +0,0 @@
-/* Copyright (C) 2009-2014 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 <tcb-offsets.h>
-
-/* Save the PID value.  */
-#define SAVE_PID							\
-	mrs	x2, tpidr_el0;						\
-	sub	x2, x2, #PTHREAD_SIZEOF;				\
-	ldr	w3, [x2, #PTHREAD_PID_OFFSET];				\
-	neg	w0, w3;							\
-	str	w0, [x2, #PTHREAD_PID_OFFSET]
-
-/* Restore the old PID value in the parent.  */
-#define RESTORE_PID                                                     \
-	cbz	x0, 1f;							\
-	str	w3, [x2, #PTHREAD_PID_OFFSET];				\
-1:
-
-#include "../vfork.S"
diff --git a/sysdeps/unix/sysv/linux/aarch64/pt-vfork.c b/sysdeps/unix/sysv/linux/aarch64/pt-vfork.c
new file mode 100644
index 0000000..5dd23bf
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/aarch64/pt-vfork.c
@@ -0,0 +1,54 @@
+/* vfork ABI-compatibility entry points for libpthread.
+   Copyright (C) 2014 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 <shlib-compat.h>
+
+/* libpthread used to have its own vfork implementation that differed
+   from libc's only in having a pointless micro-optimization.  There
+   is no longer any use to having a separate copy in libpthread, but
+   the historical ABI requires it.  For static linking, there is no
+   need to provide anything here--the libc version will be linked in.
+   For shared library ABI compatibility, there must be __vfork and
+   vfork symbols in libpthread.so.  */
+
+#if HAVE_IFUNC
+# include <nptl/pt-vfork.c>
+#elif (SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_20) \
+       || SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_20))
+
+/* Thankfully, on AArch64 we can rely on the compiler generating
+   a tail call here.  */
+
+extern void __libc_vfork (void);
+
+void
+vfork_compat (void)
+{
+  __libc_vfork ();
+}
+
+# if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_20)
+compat_symbol (libpthread, vfork_compat, vfork, GLIBC_2_0);
+# endif
+
+# if SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_20)
+strong_alias (vfork_compat, vfork_compat2)
+compat_symbol (libpthread, vfork_compat2, __vfork, GLIBC_2_1_2);
+# endif
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/aarch64/vfork.S b/sysdeps/unix/sysv/linux/aarch64/vfork.S
index d9f2c70..316cb65 100644
--- a/sysdeps/unix/sysv/linux/aarch64/vfork.S
+++ b/sysdeps/unix/sysv/linux/aarch64/vfork.S
@@ -28,22 +28,33 @@
 
 ENTRY (__vfork)
 
-#ifdef SAVE_PID
-	SAVE_PID
-#endif
+	/* Save the TCB-cached PID away in w3, and then negate the TCB
+           field.  But if it's zero, set it to 0x80000000 instead.  See
+           raise.c for the logic that relies on this value.  */
+	mrs	x2, tpidr_el0
+	sub	x2, x2, #PTHREAD_SIZEOF
+	ldr	w3, [x2, #PTHREAD_PID_OFFSET]
+	mov	w1, #0x80000000
+	negs	w0, w3
+	csel	w0, w1, w0, eq
+	str	w0, [x2, #PTHREAD_PID_OFFSET]
+
 	mov	x0, #0x4111	/* CLONE_VM | CLONE_VFORK | SIGCHLD */
 	mov	x1, sp
 	DO_CALL (clone, 2)
-#ifdef RESTORE_PID
-	RESTORE_PID
-#endif
+
+	/* Restore the original value of the TCB cache of the PID, if we're
+	   the parent.  But in the child (syscall return value equals zero),
+	   leave things as they are.  */
+	cbz	x0, 1f
+	str	w3, [x2, #PTHREAD_PID_OFFSET]
+1:
 	cmn	x0, #4095
-	b.cs    1f
+	b.cs    .Lsyscall_error
 	RET
-1:
-	b	SYSCALL_ERROR
 
 PSEUDO_END (__vfork)
 libc_hidden_def (__vfork)
 
 weak_alias (__vfork, vfork)
+strong_alias (__vfork, __libc_vfork)
-- 
1.9.0