lowlevelrobustlock.S

/* Copyright (C) 2002-2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.

   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 <pthread-errnos.h>
#include <lowlevellock.h>
#include <lowlevelrobustlock.h>
#include <kernel-features.h>

	.text

#define FUTEX_WAITERS		0x80000000
#define FUTEX_OWNER_DIED	0x40000000

#ifdef __ASSUME_PRIVATE_FUTEX
# define LOAD_FUTEX_WAIT(reg) \
	xorl	$(FUTEX_WAIT | FUTEX_PRIVATE_FLAG), reg
# define LOAD_FUTEX_WAIT_ABS(reg) \
	xorl	$(FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME), reg
#else
# if FUTEX_WAIT == 0
#  define LOAD_FUTEX_WAIT(reg) \
	xorl	$FUTEX_PRIVATE_FLAG, reg ; \
	andl	%fs:PRIVATE_FUTEX, reg
# else
#  define LOAD_FUTEX_WAIT(reg) \
	xorl	$FUTEX_PRIVATE_FLAG, reg ; \
	andl	%fs:PRIVATE_FUTEX, reg ; \
	orl	$FUTEX_WAIT, reg
# endif
# define LOAD_FUTEX_WAIT_ABS(reg) \
	xorl	$FUTEX_PRIVATE_FLAG, reg ; \
	andl	%fs:PRIVATE_FUTEX, reg ; \
	orl	$FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME, reg
#endif


	.globl	__lll_robust_lock_wait
	.type	__lll_robust_lock_wait,@function
	.hidden	__lll_robust_lock_wait
	.align	16
__lll_robust_lock_wait:
	cfi_startproc
	pushq	%r10
	cfi_adjust_cfa_offset(8)
	pushq	%rdx
	cfi_adjust_cfa_offset(8)
	cfi_offset(%r10, -16)
	cfi_offset(%rdx, -24)

	xorq	%r10, %r10	/* No timeout.  */
	LOAD_FUTEX_WAIT (%esi)

4:	movl	%eax, %edx
	orl	$FUTEX_WAITERS, %edx

	testl	$FUTEX_OWNER_DIED, %eax
	jnz	3f

	cmpl	%edx, %eax
	je	1f

	LOCK
	cmpxchgl %edx, (%rdi)
	jnz	2f

1:	movl	$SYS_futex, %eax
	syscall

	movl	(%rdi), %eax

2:	testl	%eax, %eax
	jne	4b

	movl	%fs:TID, %edx
	orl	$FUTEX_WAITERS, %edx
	LOCK
	cmpxchgl %edx, (%rdi)
	jnz	4b
	/* NB:	 %rax == 0 */

3:	popq	%rdx
	cfi_adjust_cfa_offset(-8)
	cfi_restore(%rdx)
	popq	%r10
	cfi_adjust_cfa_offset(-8)
	cfi_restore(%r10)
	retq
	cfi_endproc
	.size	__lll_robust_lock_wait,.-__lll_robust_lock_wait


	.globl	__lll_robust_timedlock_wait
	.type	__lll_robust_timedlock_wait,@function
	.hidden	__lll_robust_timedlock_wait
	.align	16
__lll_robust_timedlock_wait:
	cfi_startproc
# ifndef __ASSUME_FUTEX_CLOCK_REALTIME
#  ifdef PIC
	cmpl	$0, __have_futex_clock_realtime(%rip)
#  else
	cmpl	$0, __have_futex_clock_realtime
#  endif
	je	.Lreltmo
# endif

	cmpq	$0, (%rdx)
	js	7f

	pushq	%r9
	cfi_adjust_cfa_offset(8)
	cfi_rel_offset(%r9, 0)
	movq	%rdx, %r10
	movl	$0xffffffff, %r9d
	LOAD_FUTEX_WAIT_ABS (%esi)

1:	testl	$FUTEX_OWNER_DIED, %eax
	jnz	3f

	movl	%eax, %edx
	orl	$FUTEX_WAITERS, %edx

	cmpl	%eax, %edx
	je	5f

	LOCK
	cmpxchgl %edx, (%rdi)
	movq	$0, %rcx	/* Must use mov to avoid changing cc.  */
	jnz	6f

5:	movl	$SYS_futex, %eax
	syscall
	movl	%eax, %ecx

	movl	(%rdi), %eax

6:	testl	%eax, %eax
	jne	2f

	movl	%fs:TID, %edx
	orl	$FUTEX_WAITERS, %edx
	LOCK
	cmpxchgl %edx, (%rdi)
	jnz	2f

3:	popq	%r9
	cfi_adjust_cfa_offset(-8)
	cfi_restore(%r9)
	retq

	cfi_adjust_cfa_offset(8)
	cfi_rel_offset(%r9, 0)
	/* Check whether the time expired.  */
2:	cmpl	$-ETIMEDOUT, %ecx
	je	4f
	cmpl	$-EINVAL, %ecx
	jne	1b

4:	movl	%ecx, %eax
	negl	%eax
	jmp	3b
	cfi_adjust_cfa_offset(-8)
	cfi_restore(%r9)

7:	movl	$ETIMEDOUT, %eax
	retq


# ifndef __ASSUME_FUTEX_CLOCK_REALTIME
.Lreltmo:
	/* Check for a valid timeout value.  */
	cmpq	$1000000000, 8(%rdx)
	jae	3f

	pushq	%r8
	cfi_adjust_cfa_offset(8)
	pushq	%r9
	cfi_adjust_cfa_offset(8)
	pushq	%r12
	cfi_adjust_cfa_offset(8)
	pushq	%r13
	cfi_adjust_cfa_offset(8)
	cfi_offset(%r8, -16)
	cfi_offset(%r9, -24)
	cfi_offset(%r12, -32)
	cfi_offset(%r13, -40)
	pushq	%rsi
	cfi_adjust_cfa_offset(8)

	/* Stack frame for the timespec and timeval structs.  */
	subq	$32, %rsp
	cfi_adjust_cfa_offset(32)

	movq	%rdi, %r12
	movq	%rdx, %r13

1:	movq	%rax, 16(%rsp)

	/* Get current time.  */
	movq	%rsp, %rdi
	xorl	%esi, %esi
	/* This call works because we directly jump to a system call entry
	   which preserves all the registers.  */
	call	JUMPTARGET(__gettimeofday)

	/* Compute relative timeout.  */
	movq	8(%rsp), %rax
	movl	$1000, %edi
	mul	%rdi		/* Milli seconds to nano seconds.  */
	movq	(%r13), %rdi
	movq	8(%r13), %rsi
	subq	(%rsp), %rdi
	subq	%rax, %rsi
	jns	4f
	addq	$1000000000, %rsi
	decq	%rdi
4:	testq	%rdi, %rdi
	js	8f		/* Time is already up.  */

	/* Futex call.  */
	movq	%rdi, (%rsp)	/* Store relative timeout.  */
	movq	%rsi, 8(%rsp)

	movq	16(%rsp), %rdx
	movl	%edx, %eax
	orl	$FUTEX_WAITERS, %edx

	testl	$FUTEX_OWNER_DIED, %eax
	jnz	6f

	cmpl	%eax, %edx
	je	2f

	LOCK
	cmpxchgl %edx, (%r12)
	movq	$0, %rcx	/* Must use mov to avoid changing cc.  */
	jnz	5f

2:	movq	%rsp, %r10
	movl	32(%rsp), %esi
	LOAD_FUTEX_WAIT (%esi)
	movq	%r12, %rdi
	movl	$SYS_futex, %eax
	syscall
	movq	%rax, %rcx

	movl	(%r12), %eax

5:	testl	%eax, %eax
	jne	7f

	movl	%fs:TID, %edx
	orl	$FUTEX_WAITERS, %edx
	LOCK
	cmpxchgl %edx, (%r12)
	jnz	7f

6:	addq	$40, %rsp
	cfi_adjust_cfa_offset(-40)
	popq	%r13
	cfi_adjust_cfa_offset(-8)
	cfi_restore(%r13)
	popq	%r12
	cfi_adjust_cfa_offset(-8)
	cfi_restore(%r12)
	popq	%r9
	cfi_adjust_cfa_offset(-8)
	cfi_restore(%r9)
	popq	%r8
	cfi_adjust_cfa_offset(-8)
	cfi_restore(%r8)
	retq

3:	movl	$EINVAL, %eax
	retq

	cfi_adjust_cfa_offset(72)
	cfi_offset(%r8, -16)
	cfi_offset(%r9, -24)
	cfi_offset(%r12, -32)
	cfi_offset(%r13, -40)
	/* Check whether the time expired.  */
7:	cmpl	$-ETIMEDOUT, %ecx
	jne	1b

8:	movl	$ETIMEDOUT, %eax
	jmp	6b
#endif
	cfi_endproc
	.size	__lll_robust_timedlock_wait,.-__lll_robust_timedlock_wait