[glibc/azanella/bz12683] nptl: m68k: Fix Race conditions in pthread cancellation (BZ#12683)

[Adhemerval Zanella <azanella at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d22512b88914013b237bae376227156717318e35

commit d22512b88914013b237bae376227156717318e35
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Jan 9 10:12:16 2019 -0200

    nptl: m68k: Fix Race conditions in pthread cancellation (BZ#12683)
    
    This patch adds the m68k modifications required for the BZ#12683 fix
    by adding the arch-specific cancellation syscall bridge.
    
    Checked on m68k-linux-gnu.

Diff:
---
 sysdeps/m68k/nptl/tcb-offsets.sym             |  3 +
 sysdeps/unix/sysv/linux/m68k/syscall_cancel.S | 85 +++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/sysdeps/m68k/nptl/tcb-offsets.sym b/sysdeps/m68k/nptl/tcb-offsets.sym
index 241fb8b..59c9f78 100644
--- a/sysdeps/m68k/nptl/tcb-offsets.sym
+++ b/sysdeps/m68k/nptl/tcb-offsets.sym
@@ -8,3 +8,6 @@
 
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
 TID_OFFSET			thread_offsetof (tid)
+
+-- Not strictly offsets, used on syscall_cancel.S
+TCB_CANCELED_BIT		CANCELED_BIT
diff --git a/sysdeps/unix/sysv/linux/m68k/syscall_cancel.S b/sysdeps/unix/sysv/linux/m68k/syscall_cancel.S
new file mode 100644
index 0000000..191b689
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/m68k/syscall_cancel.S
@@ -0,0 +1,85 @@
+/* Cancellable syscall wrapper.  Linux/m68k version.
+   Copyright (C) 2019 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 <sysdep.h>
+
+/* long int __syscall_cancel_arch (int *cancelhandling,
+				   __syscall_arg_t nr,
+				   __syscall_arg_t arg1,
+				   __syscall_arg_t arg2,
+				   __syscall_arg_t arg3,
+				   __syscall_arg_t arg4,
+				   __syscall_arg_t arg5,
+				   __syscall_arg_t arg6,
+				   __syscall_arg_t arg7)  */
+
+
+ENTRY (__syscall_cancel_arch)
+#ifdef __mcoldfire__
+	lea	(-16,%sp),%sp
+	movem.l	#60,(%sp)
+#else
+	movem.l	#15360,-(%sp)
+#endif
+	cfi_def_cfa_offset (20)
+	cfi_offset (2, -20)
+	cfi_offset (3, -16)
+	cfi_offset (4, -12)
+	cfi_offset (5, -8)
+
+	.global __syscall_cancel_arch_start
+__syscall_cancel_arch_start:
+
+	move.l	20(%sp),%a0
+	move.l	(%a0),%d0
+#ifdef __mcoldfire__
+	move.w	%d0,%ccr
+	jeq	1f
+#else
+	btst	#TCB_CANCELED_BIT,%d0
+	jne 	1f
+#endif
+
+	move.l	48(%sp),%a0
+	move.l	44(%sp),%d5
+	move.l	40(%sp),%d4
+	move.l	36(%sp),%d3
+	move.l	32(%sp),%d2
+	move.l	28(%sp),%d1
+	move.l	24(%sp),%d0
+	trap #0
+
+	.global __syscall_cancel_arch_end
+__syscall_cancel_arch_end:
+
+#ifdef __mcoldfire__
+	movem.l	(%sp),#60
+	lea	(16,%sp),%sp
+#else
+	movem.l	(%sp)+,#60
+#endif
+	rts
+
+1:
+#ifdef PIC
+	bsr.l __syscall_do_cancel
+#else
+	jsr __syscall_do_cancel
+#endif
+END (__syscall_cancel_arch)
+libc_hidden_def (__syscall_cancel_arch)