[PATCH v3 12/21] nptl: sparc: Fix Race conditions in pthread cancellation (BZ#12683)

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

This patch adds the sparc modifications required for the BZ#12683 fix.

Different than other architectures, SPARC passes the sigcontext_t
struct pointer as third argument in the signal handler set with
SA_SIGINFO (some info at [1]) for 64 bits and the pt_regs in 32 bits.
>From Linux code:

* arch/sparc/kernel/signal_64.c

428         /* 3. signal handler back-trampoline and parameters */
429         regs->u_regs[UREG_FP] = ((unsigned long) sf) - STACK_BIAS;
430         regs->u_regs[UREG_I0] = ksig->sig;
431         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
432
433         /* The sigcontext is passed in this way because of how it
434          * is defined in GLIBC's /usr/include/bits/sigcontext.h
435          * for sparc64.  It includes the 128 bytes of siginfo_t.
436          */
437         regs->u_regs[UREG_I2] = (unsigned long) &sf->info;

* arch/sparc/kernel/signal_32.c:

392         regs->u_regs[UREG_FP] = (unsigned long) sf;
393         regs->u_regs[UREG_I0] = ksig->sig;
394         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
395         regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;
396
397         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
398         regs->npc = (regs->pc + 4);

So it requires an arch-specific ucontext_add_cancel.

Also on sparc interrupted pause syscall returns with a PC indicating a
side-effect and this deviates from other architectures.  The sparc64
pause fall back to ppool syscall.

Checked on sparc64-linux-gnu and sparcv9-linux-gnu.

[1] https://www.spinics.net/lists/sparclinux/msg05037.html
---
 .../sysv/linux/sparc/cancellation-sigmask.h   | 39 ++++++++++
 .../sysv/linux/sparc/sparc32/syscall_cancel.S | 76 ++++++++++++++++++
 sysdeps/unix/sysv/linux/sparc/sparc64/pause.c | 25 ++++++
 .../sysv/linux/sparc/sparc64/syscall_cancel.S | 77 +++++++++++++++++++
 4 files changed, 217 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/sparc/cancellation-sigmask.h
 create mode 100644 sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S
 create mode 100644 sysdeps/unix/sysv/linux/sparc/sparc64/pause.c
 create mode 100644 sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S

diff --git a/sysdeps/unix/sysv/linux/sparc/cancellation-sigmask.h b/sysdeps/unix/sysv/linux/sparc/cancellation-sigmask.h
new file mode 100644
index 0000000000..6fd889b1cc
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/cancellation-sigmask.h
@@ -0,0 +1,39 @@
+/* Architecture specific bits for cancellation handling.
+   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/>.  */
+
+#ifndef _NPTL_CANCELLATION_SIGMASK_H
+#define _NPTL_CANCELLATION_SIGMASK_H 1
+
+/* Add the SIGCANCEL signal on sigmask set at the ucontext CTX obtained from
+   the sigaction handler.  */
+static void
+ucontext_add_cancel (void *ctx)
+{
+  sigset_t *set;
+#ifdef __arch64__
+  struct pt_regs *regs = (struct pt_regs*) ((siginfo_t *)(ctx) + 1);
+  __siginfo_fpu_t *f = (__siginfo_fpu_t *)(regs + 1);
+  set = (sigset_t *) ((stack_t *)(f + 1) + 1);
+#else
+  struct pt_regs32 *ptregs = (struct pt_regs32 *) (ctx);
+  set = (sigset_t *) (ptregs + 1);
+#endif
+  __sigaddset (set, SIGCANCEL);
+}
+
+#endif
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S b/sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S
new file mode 100644
index 0000000000..7c86dee33c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/syscall_cancel.S
@@ -0,0 +1,76 @@
+/* Cancellable syscall wrapper.  Linux/sparc32 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,
+				   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)
+	save	%sp, -96, %sp
+
+	cfi_window_save
+	cfi_register (%o7, %i7)
+	cfi_def_cfa_register (%fp)
+
+	.globl __syscall_cancel_arch_start
+	.type  __syscall_cancel_arch_start, @function
+__syscall_cancel_arch_start:
+
+	/* if (*cancelhandling & CANCELED_BITMASK)
+	     __syscall_do_cancel()  */
+	ld	[%i0], %g2
+	andcc	%g2, 4, %g0
+	bne,pn	%icc, 2f
+
+	/* Issue a 6 argument syscall.  */
+	 mov	%i2, %o0
+	mov	%i3, %o1
+	ld	[%fp+92], %o4
+	mov	%i4, %o2
+	mov	%i5, %o3
+	ld	[%fp+96], %o5
+	mov	%i1, %g1
+	ta	0x10
+
+	.globl __syscall_cancel_arch_end
+	.type  __syscall_cancel_arch_end, @function
+__syscall_cancel_arch_end:
+	bcc	1f
+	mov	0, %g1
+	sub	%g0, %o0, %o0
+	mov	1, %g1
+
+1:
+	mov	%o0, %i0
+	return	%i7+8
+	 nop
+
+2:
+	call	__syscall_do_cancel, 0
+	 nop
+	nop
+
+END (__syscall_cancel_arch)
+libc_hidden_def (__syscall_cancel_arch)
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/pause.c b/sysdeps/unix/sysv/linux/sparc/sparc64/pause.c
new file mode 100644
index 0000000000..4a0cf4db59
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/pause.c
@@ -0,0 +1,25 @@
+/* Linux pause syscall implementation.  Linux/sparc64.
+   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 <sys/syscall.h>
+
+/* On sparc interrupted pause syscall returns with a PC indicating a
+   side-effect and this deviates from other architectures.  Fall back to
+   ppool implementation.  */
+#undef __NR_pause
+#include <sysdeps/unix/sysv/linux/pause.c>
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S b/sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S
new file mode 100644
index 0000000000..8a6d5a2fd8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/syscall_cancel.S
@@ -0,0 +1,77 @@
+/* Cancellable syscall wrapper.  Linux/sparc64 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>
+
+	.register       %g2, #scratch
+
+/* 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)
+	save	%sp, -176, %sp
+	cfi_window_save
+	cfi_def_cfa_register (%fp)
+	cfi_register (%o7, %i7)
+
+	.globl __syscall_cancel_arch_start
+	.type  __syscall_cancel_arch_start, @function
+__syscall_cancel_arch_start:
+
+	/* if (*cancelhandling & CANCELED_BITMASK)
+	     __syscall_do_cancel()  */
+	lduw	[%i0], %g2
+	andcc	%g2, 4, %g0
+	bne,pn	%xcc, 2f
+
+	/* Issue a 6 argument syscall.  */
+	 mov	%i2, %o0
+	mov	%i3, %o1
+	mov	%i4, %o2
+	mov	%i5, %o3
+	ldx	[%fp + STACK_BIAS + 176], %o4
+	ldx	[%fp + STACK_BIAS + 184], %o5
+	mov	%i1, %g1
+	ta	0x6d
+
+	.global __syscall_cancel_arch_end
+	.type   __syscall_cancel_arch_end, @function
+__syscall_cancel_arch_end:
+
+	bcc,pt	%xcc, 1f
+	mov	0, %g1
+	sub	%g0, %o0, %o0
+	mov	1, %g1
+1:
+	mov	%o0, %i0
+	return	%i7+8
+	 nop
+
+2:
+	call	__syscall_do_cancel, 0
+	 nop
+	nop
+
+END (__syscall_cancel_arch)
+libc_hidden_def (__syscall_cancel_arch)
-- 
2.17.1