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

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=3ed6ae1cee175c67865cfee0e0247febe107bcc4

commit 3ed6ae1cee175c67865cfee0e0247febe107bcc4
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Jan 9 15:32:09 2019 -0200

    nptl: riscv: Fix Race conditions in pthread cancellation [BZ#12683]
    
    This patch adds the riscv modifications required for the BZ#12683 fix
    by adding the arch-specific cancellation syscall bridge.
    
    Reviewed-by: Andrew Waterman <aswaterman@gmail.com>

Diff:
---
 sysdeps/riscv/nptl/tcb-offsets.sym             |  3 ++
 sysdeps/riscv/nptl/tls.h                       |  2 +
 sysdeps/unix/sysv/linux/riscv/syscall_cancel.S | 67 ++++++++++++++++++++++++++
 3 files changed, 72 insertions(+)

diff --git a/sysdeps/riscv/nptl/tcb-offsets.sym b/sysdeps/riscv/nptl/tcb-offsets.sym
index ab4981f2e2..bcee223d1e 100644
--- a/sysdeps/riscv/nptl/tcb-offsets.sym
+++ b/sysdeps/riscv/nptl/tcb-offsets.sym
@@ -4,3 +4,6 @@
 #define thread_offsetof(mem)	(long)(offsetof (struct pthread, mem) - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE)
 
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
+
+-- Not strictly offsets, used on syscall_cancel.S
+TCB_CANCELED_BITMASK		CANCELED_BITMASK
diff --git a/sysdeps/riscv/nptl/tls.h b/sysdeps/riscv/nptl/tls.h
index a9167bc143..21e9124564 100644
--- a/sysdeps/riscv/nptl/tls.h
+++ b/sysdeps/riscv/nptl/tls.h
@@ -142,6 +142,8 @@ typedef struct
 # define THREAD_GSCOPE_WAIT() \
   GL(dl_wait_lookup_done) ()
 
+#else /* __ASSEMBLER__ */
+# include <tcb-offsets.h>
 #endif /* __ASSEMBLER__ */
 
 #endif	/* tls.h */
diff --git a/sysdeps/unix/sysv/linux/riscv/syscall_cancel.S b/sysdeps/unix/sysv/linux/riscv/syscall_cancel.S
new file mode 100644
index 0000000000..520e25aa3a
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/riscv/syscall_cancel.S
@@ -0,0 +1,67 @@
+/* Cancellable syscall wrapper.  Linux/riscv version.
+   Copyright (C) 2020 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)  */
+
+#ifdef SHARED
+	.option pic
+#else
+	.option nopic
+#endif
+
+ENTRY (__syscall_cancel_arch)
+	mv	t1, a7
+
+	.globl __syscall_cancel_arch_start
+__syscall_cancel_arch_start:
+	lw	a7, 0(a0)
+	/* if (*ch & CANCELED_BITMASK)  */
+	andi	a7, a7, TCB_CANCELED_BITMASK
+	bnez	a7, 1f
+
+	mv	a7,a1
+	mv	a0,a2
+	mv	a1,a3
+	mv	a2,a4
+	mv	a3,a5
+	mv	a4,a6
+	mv	a5,t1
+	scall
+
+	.globl __syscall_cancel_arch_end
+__syscall_cancel_arch_end:
+	ret
+
+1:
+	addi	sp, sp, -16
+	cfi_def_cfa_offset (16)
+	sd	ra, 8(sp)
+	cfi_offset (ra, -8)
+	call	__syscall_do_cancel
+
+END (__syscall_cancel_arch)
+libc_hidden_def (__syscall_cancel_arch)