[PATCH v2 18/21] nptl: sh: Fix Race conditions in pthread cancellation (BZ#12683)

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

This patch adds the sh modifications required for the BZ#12683.
It basically adds the required ucontext_get_pc function and a
cancellable syscall wrapper.

SH requires an arch-specific syscall_cancel because the
INTERNAL_SYSCALL_NCS adds the required or instruction to workaround
a hardware bug [1].  The implementation were based on on default C
version built with GCC 6.2.1.

Checked against a build and make check run-built-tests=no for
sh4-linux-gnu.

	[BZ #12683]
	* sysdeps/unix/sysv/linux/sh/syscall_cancel.S: New file.
	* sysdeps/unix/sysv/linux/sh/sigcontextinfo.h (ucontext_get_pc):
	New function.

[1] http://documentation.renesas.com/eng/products/mpumcu/tu/tnsh7456ae.pdf
---
 ChangeLog                                   |   6 ++
 sysdeps/sh/sysdep.h                         |   1 +
 sysdeps/unix/sysv/linux/sh/sigcontextinfo.h |  11 +++
 sysdeps/unix/sysv/linux/sh/syscall_cancel.S | 125 ++++++++++++++++++++++++++++
 4 files changed, 143 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/sh/syscall_cancel.S

diff --git a/sysdeps/sh/sysdep.h b/sysdeps/sh/sysdep.h
index 37889fb..df34c4c 100644
--- a/sysdeps/sh/sysdep.h
+++ b/sysdeps/sh/sysdep.h
@@ -24,6 +24,7 @@
 
 #define ALIGNARG(log2) log2
 #define ASM_SIZE_DIRECTIVE(name) .size name,.-name
+#define L(label) .L##label
 
 #ifdef SHARED
 #define PLTJMP(_x)	_x##@PLT
diff --git a/sysdeps/unix/sysv/linux/sh/sigcontextinfo.h b/sysdeps/unix/sysv/linux/sh/sigcontextinfo.h
index d6dd48d..239f931 100644
--- a/sysdeps/unix/sysv/linux/sh/sigcontextinfo.h
+++ b/sysdeps/unix/sysv/linux/sh/sigcontextinfo.h
@@ -16,6 +16,9 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef _SIGCONTEXTINFO_H
+#define _SIGCONTEXTINFO_H
+
 #define SIGCONTEXT int _a2, int _a3, int _a4, struct sigcontext
 
 #define SIGCONTEXT_EXTRA_ARGS _a2, _a3, _a4,
@@ -24,3 +27,11 @@
 #define GET_STACK(ctx)	((void *) ctx.sc_regs[15])
 #define CALL_SIGHANDLER(handler, signo, ctx) \
   (handler)((signo), SIGCONTEXT_EXTRA_ARGS (ctx))
+
+static inline uintptr_t
+ucontext_get_pc (const ucontext_t *uc)
+{
+  return uc->uc_mcontext.pc;
+}
+
+#endif /* _SIGCONTEXTINFO_H  */
diff --git a/sysdeps/unix/sysv/linux/sh/syscall_cancel.S b/sysdeps/unix/sysv/linux/sh/syscall_cancel.S
new file mode 100644
index 0000000..02a050d
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sh/syscall_cancel.S
@@ -0,0 +1,125 @@
+/* Cancellable syscall wrapper.  Linux/sh version.
+   Copyright (C) 2017 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,
+				   long int nr,
+				   long int arg1,
+				   long int arg2,
+				   long int arg3,
+				   long int arg4,
+				   long int arg5,
+				   long int arg6)  */
+
+ENTRY (__syscall_cancel_arch)
+
+#ifdef SHARED
+	mov.l	r12,@-r15
+	cfi_def_cfa_offset (4)
+	cfi_offset (12, -4)
+	mova	L(GT),r0
+	mov.l	L(GT),r12
+	sts.l	pr,@-r15
+	cfi_def_cfa_offset (8)
+	cfi_offset (17, -8)
+	add	r0,r12
+#else
+	sts.l	pr,@-r15
+	cfi_def_cfa_offset (4)
+	cfi_offset (17, -4)
+#endif
+
+	.globl __syscall_cancel_arch_start
+__syscall_cancel_arch_start:
+
+	/* if (*cancelhandling & CANCELED_BITMASK)
+	     __syscall_do_cancel()  */
+	mov.l	@r4,r0
+	tst	#4,r0
+	bf/s	1f
+
+	/* Issue a 6 argument syscall.  */
+	mov	r5,r3
+	mov	r6,r4
+	mov	r7,r5
+#ifdef SHARED
+	mov.l	@(8,r15),r6
+	mov.l	@(12,r15),r7
+	mov.l	@(16,r15),r0
+	mov.l	@(20,r15),r1
+#else
+	mov.l	@(4,r15),r6
+	mov.l	@(8,r15),r7
+	mov.l	@(12,r15),r0
+	mov.l	@(16,r15),r1
+#endif
+	trapa	#0x16
+
+/* The additional or is a workaround for a hardware issue:
+   http://documentation.renesas.com/eng/products/mpumcu/tu/tnsh7456ae.pdf  */
+	.globl __syscall_cancel_arch_end
+__syscall_cancel_arch_end:
+
+	or	r0,r0
+	or	r0,r0
+	or	r0,r0
+	or	r0,r0
+	or	r0,r0
+
+	lds.l	@r15+,pr
+	cfi_remember_state
+	cfi_restore (17)
+#ifdef SHARED
+	cfi_def_cfa_offset (4)
+	rts
+	mov.l	@r15+,r12
+	cfi_def_cfa_offset (0)
+	cfi_restore (12)
+	.align 1
+1:
+	cfi_restore_state
+	mov.l	L(SC),r1
+	bsrf	r1
+L(M):
+	nop
+
+	.align 2
+L(GT):
+	.long	_GLOBAL_OFFSET_TABLE_
+L(SC):
+	.long	__syscall_do_cancel-(L(M)+2)
+#else
+	cfi_def_cfa_offset (0)
+	rts
+	nop
+
+	.align 1
+1:
+	cfi_restore_state
+	mov.l	2f,r1
+	jsr	@r1
+	nop
+
+	.align 2
+2:
+	.long	__syscall_do_cancel
+#endif
+
+END (__syscall_cancel_arch)
+libc_hidden_def (__syscall_cancel_arch)
-- 
2.7.4