[glibc/azanella/bz12683] loongarch: Fix Race conditions in pthread cancellation [BZ#12683]

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=235581ee858071eacc3130ae05ad9ae16b00d1e5

commit 235581ee858071eacc3130ae05ad9ae16b00d1e5
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Mon Apr 3 15:50:35 2023 -0300

    loongarch: Fix Race conditions in pthread cancellation [BZ#12683]
    
    By adding the required syscall_cancel.S.
    
    Checked against a build and make check run-built-tests=no for
    loongarch64-linux-gnu-lp64d.

Diff:
---
 sysdeps/unix/sysv/linux/loongarch/syscall_cancel.S | 54 ++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/sysdeps/unix/sysv/linux/loongarch/syscall_cancel.S b/sysdeps/unix/sysv/linux/loongarch/syscall_cancel.S
new file mode 100644
index 0000000000..574252fec1
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/loongarch/syscall_cancel.S
@@ -0,0 +1,54 @@
+/* Cancellable syscall wrapper.  Linux/loongarch version.
+   Copyright (C) 2023 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>
+#include <descr-const.h>
+
+ENTRY (__syscall_cancel_arch)
+
+	.global __syscall_cancel_arch_start
+__syscall_cancel_arch_start:
+
+	/* if (*cancelhandling & CANCELED_BITMASK)
+	     __syscall_do_cancel()  */
+	ldptr.w	$r12,$r4,0
+	andi	$r12,$r12,TCB_CANCELED_BITMASK
+	bnez	$r12,1f
+
+	/* Issue a 6 argument syscall.  */
+	or	$r13,$r5,$r0
+	or	$r4,$r6,$r0
+	or	$r5,$r7,$r0
+	or	$r6,$r8,$r0
+	or	$r7,$r9,$r0
+	or	$r8,$r10,$r0
+	or	$r9,$r11,$r0
+	or	$r11,$r13,$r0
+	syscall 0
+
+	.global __syscall_cancel_arch_end
+__syscall_cancel_arch_end:
+	jr	$r1
+1:
+	addi.d	$r3,$r3,-16
+	cfi_def_cfa_offset (16)
+	st.d	$r1,$r3,8
+	cfi_offset (1, -8)
+	bl	__syscall_do_cancel
+
+END (__syscall_cancel_arch)