robust mutexes: Fix broken x86 assembly by removing it

lll_robust_unlock on i386 and x86_64 first sets the futex word to
FUTEX_WAITERS|0 before calling __lll_unlock_wake, which will set the
futex word to 0.  If the thread is killed between these steps, then the
futex word will be FUTEX_WAITERS|0, and the kernel (at least current
upstream) will not set it to FUTEX_OWNER_DIED|FUTEX_WAITERS because 0 is
not equal to the TID of the crashed thread.

The lll_robust_lock assembly code on i386 and x86_64 is not prepared to
deal with this case because the fastpath tries to only CAS 0 to TID and
not FUTEX_WAITERS|0 to TID; the slowpath simply waits until it can CAS 0
to TID or the futex_word has the FUTEX_OWNER_DIED bit set.

This issue is fixed by removing the custom x86 assembly code and using
the generic C code instead.  However, instead of adding more duplicate
code to the custom x86 lowlevellock.h, the code of the lll_robust* functions
is inlined into the single call sites that exist for each of these functions
in the pthread_mutex_* functions.  The robust mutex paths in the latter
have been slightly reorganized to make them simpler.

This patch is meant to be easy to backport, so C11-style atomics are not
used.

	[BZ #20985]
	* nptl/Makefile: Adapt.
	* nptl/pthread_mutex_cond_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove.
	(LLL_ROBUST_MUTEX_LOCK_MODIFIER): New.
	* nptl/pthread_mutex_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove.
	(LLL_ROBUST_MUTEX_LOCK_MODIFIER): New.
	(__pthread_mutex_lock_full): Inline lll_robust* functions and adapt.
	* nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Inline
	lll_robust* functions and adapt.
	* nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
	* sysdeps/nptl/lowlevellock.h (__lll_robust_lock_wait,
	__lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait,
	__lll_robust_timedlock, __lll_robust_unlock): Remove.
	* sysdeps/unix/sysv/linux/i386/lowlevellock.h (lll_robust_lock,
	lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove.
	* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h (lll_robust_lock,
	lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove.
	* sysdeps/unix/sysv/linux/sparc/lowlevellock.h (__lll_robust_lock_wait,
	__lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait,
	__lll_robust_timedlock, __lll_robust_unlock): Remove.
	* nptl/lowlevelrobustlock.c: Remove file.
	* nptl/lowlevelrobustlock.sym: Likewise.
	* sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/lowlevelrobustlock.S: Likewise.

2 files changed, 0 insertions, 292 deletions

diff --git a/sysdeps/unix/sysv/linux/i386/lowlevellock.h b/sysdeps/unix/sysv/linux/i386/lowlevellock.h
index 31946a5172..197bb1fcd9 100644
--- a/sysdeps/unix/sysv/linux/i386/lowlevellock.h
+++ b/sysdeps/unix/sysv/linux/i386/lowlevellock.h
@@ -132,20 +132,6 @@
 	 }								      \
     })
 
-#define lll_robust_lock(futex, id, private) \
-  ({ int result, ignore1, ignore2;					      \
-     __asm __volatile (LOCK_INSTR "cmpxchgl %1, %2\n\t"			      \
-		       "jz 18f\n\t"					      \
-		       "1:\tleal %2, %%edx\n"				      \
-		       "0:\tmovl %7, %%ecx\n"				      \
-		       "2:\tcall __lll_robust_lock_wait\n"		      \
-		       "18:"						      \
-		       : "=a" (result), "=c" (ignore1), "=m" (futex),	      \
-			 "=&d" (ignore2)				      \
-		       : "0" (0), "1" (id), "m" (futex), "g" ((int) (private))\
-		       : "memory");					      \
-     result; })
-
 
 /* Special version of lll_lock which causes the unlock function to
    always wakeup waiters.  */
@@ -165,22 +151,6 @@
     })
 
 
-#define lll_robust_cond_lock(futex, id, private) \
-  ({ int result, ignore1, ignore2;					      \
-     __asm __volatile (LOCK_INSTR "cmpxchgl %1, %2\n\t"			      \
-		       "jz 18f\n\t"					      \
-		       "1:\tleal %2, %%edx\n"				      \
-		       "0:\tmovl %7, %%ecx\n"				      \
-		       "2:\tcall __lll_robust_lock_wait\n"		      \
-		       "18:"						      \
-		       : "=a" (result), "=c" (ignore1), "=m" (futex),	      \
-			 "=&d" (ignore2)				      \
-		       : "0" (0), "1" (id | FUTEX_WAITERS), "m" (futex),      \
-			 "g" ((int) (private))				      \
-		       : "memory");					      \
-     result; })
-
-
 #define lll_timedlock(futex, timeout, private) \
   ({ int result, ignore1, ignore2, ignore3;				      \
      __asm __volatile (LOCK_INSTR "cmpxchgl %1, %3\n\t"			      \
@@ -203,21 +173,6 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
 #define lll_timedlock_elision(futex, adapt_count, timeout, private)	\
   __lll_timedlock_elision(&(futex), &(adapt_count), timeout, private)
 
-#define lll_robust_timedlock(futex, timeout, id, private) \
-  ({ int result, ignore1, ignore2, ignore3;				      \
-     __asm __volatile (LOCK_INSTR "cmpxchgl %1, %3\n\t"			      \
-		       "jz 18f\n\t"			   		      \
-		       "1:\tleal %3, %%ecx\n"				      \
-		       "0:\tmovl %8, %%edx\n"				      \
-		       "2:\tcall __lll_robust_timedlock_wait\n"		      \
-		       "18:"						      \
-		       : "=a" (result), "=c" (ignore1), "=&d" (ignore2),      \
-			 "=m" (futex), "=S" (ignore3)			      \
-		       : "0" (0), "1" (id), "m" (futex), "m" (timeout),	      \
-			 "4" ((int) (private))				      \
-		       : "memory");					      \
-     result; })
-
 #if !IS_IN (libc) || defined UP
 # define __lll_unlock_asm LOCK_INSTR "subl $1, %0\n\t"
 #else
@@ -255,21 +210,6 @@ extern int __lll_timedlock_elision (int *futex, short *adapt_count,
 	 }								      \
     })
 
-#define lll_robust_unlock(futex, private) \
-  (void)								      \
-    ({ int ignore, ignore2;						      \
-       __asm __volatile (LOCK_INSTR "andl %3, %0\n\t"			      \
-			 "je 18f\n\t"					      \
-			 "1:\tleal %0, %%eax\n"				      \
-			 "0:\tmovl %5, %%ecx\n"				      \
-			 "2:\tcall __lll_unlock_wake\n"			      \
-			 "18:"						      \
-			 : "=m" (futex), "=&a" (ignore), "=&c" (ignore2)      \
-			 : "i" (FUTEX_WAITERS), "m" (futex),		      \
-			   "g" ((int) (private))			      \
-			 : "memory");					      \
-    })
-
 
 #define lll_islocked(futex) \
   (futex != LLL_LOCK_INITIALIZER)
diff --git a/sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S b/sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S
deleted file mode 100644
index f3a68c0f44..0000000000
--- a/sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S
+++ /dev/null
@@ -1,232 +0,0 @@
-/* Copyright (C) 2002-2017 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
-#else
-# if FUTEX_WAIT == 0
-#  define LOAD_FUTEX_WAIT(reg) \
-	xorl	$FUTEX_PRIVATE_FLAG, reg ; \
-	andl	%gs:PRIVATE_FUTEX, reg
-# else
-#  define LOAD_FUTEX_WAIT(reg) \
-	xorl	$FUTEX_PRIVATE_FLAG, reg ; \
-	andl	%gs:PRIVATE_FUTEX, reg ; \
-	orl	$FUTEX_WAIT, reg
-# endif
-#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
-	pushl	%edx
-	cfi_adjust_cfa_offset(4)
-	pushl	%ebx
-	cfi_adjust_cfa_offset(4)
-	pushl	%esi
-	cfi_adjust_cfa_offset(4)
-	cfi_offset(%edx, -8)
-	cfi_offset(%ebx, -12)
-	cfi_offset(%esi, -16)
-
-	movl	%edx, %ebx
-	xorl	%esi, %esi	/* No timeout.  */
-	LOAD_FUTEX_WAIT (%ecx)
-
-4:	movl	%eax, %edx
-	orl	$FUTEX_WAITERS, %edx
-
-	testl	$FUTEX_OWNER_DIED, %eax
-	jnz	3f
-
-	cmpl	%edx, %eax	/* NB:	 %edx == 2 */
-	je	1f
-
-	LOCK
-	cmpxchgl %edx, (%ebx)
-	jnz	2f
-
-1:	movl	$SYS_futex, %eax
-	ENTER_KERNEL
-
-	movl	(%ebx), %eax
-
-2:	test	%eax, %eax
-	jne	4b
-
-	movl	%gs:TID, %edx
-	orl	$FUTEX_WAITERS, %edx
-	LOCK
-	cmpxchgl %edx, (%ebx)
-	jnz	4b
-	/* NB:	 %eax == 0 */
-
-3:	popl	%esi
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%esi)
-	popl	%ebx
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%ebx)
-	popl	%edx
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%edx)
-	ret
-	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
-	/* Check for a valid timeout value.  */
-	cmpl	$1000000000, 4(%edx)
-	jae	3f
-
-	pushl	%edi
-	cfi_adjust_cfa_offset(4)
-	pushl	%esi
-	cfi_adjust_cfa_offset(4)
-	pushl	%ebx
-	cfi_adjust_cfa_offset(4)
-	pushl	%ebp
-	cfi_adjust_cfa_offset(4)
-	cfi_offset(%edi, -8)
-	cfi_offset(%esi, -12)
-	cfi_offset(%ebx, -16)
-	cfi_offset(%ebp, -20)
-
-	/* Stack frame for the timespec and timeval structs.  */
-	subl	$12, %esp
-	cfi_adjust_cfa_offset(12)
-
-	movl	%ecx, %ebp
-	movl	%edx, %edi
-
-1:	movl	%eax, 8(%esp)
-
-	/* Get current time.  */
-	movl	%esp, %ebx
-	xorl	%ecx, %ecx
-	movl	$__NR_gettimeofday, %eax
-	ENTER_KERNEL
-
-	/* Compute relative timeout.  */
-	movl	4(%esp), %eax
-	movl	$1000, %edx
-	mul	%edx		/* Milli seconds to nano seconds.  */
-	movl	(%edi), %ecx
-	movl	4(%edi), %edx
-	subl	(%esp), %ecx
-	subl	%eax, %edx
-	jns	4f
-	addl	$1000000000, %edx
-	subl	$1, %ecx
-4:	testl	%ecx, %ecx
-	js	8f		/* Time is already up.  */
-
-	/* Store relative timeout.  */
-	movl	%ecx, (%esp)
-	movl	%edx, 4(%esp)
-
-	movl	%ebp, %ebx
-
-	movl	8(%esp), %edx
-	movl	%edx, %eax
-	orl	$FUTEX_WAITERS, %edx
-
-	testl	$FUTEX_OWNER_DIED, %eax
-	jnz	6f
-
-	cmpl	%eax, %edx
-	je	2f
-
-	LOCK
-	cmpxchgl %edx, (%ebx)
-	movl	$0, %ecx	/* Must use mov to avoid changing cc.  */
-	jnz	5f
-
-2:
-	/* Futex call.  */
-	movl	%esp, %esi
-	movl	20(%esp), %ecx
-	LOAD_FUTEX_WAIT (%ecx)
-	movl	$SYS_futex, %eax
-	ENTER_KERNEL
-	movl	%eax, %ecx
-
-	movl	(%ebx), %eax
-
-5:	testl	%eax, %eax
-	jne	7f
-
-	movl	%gs:TID, %edx
-	orl	$FUTEX_WAITERS, %edx
-	LOCK
-	cmpxchgl %edx, (%ebx)
-	jnz	7f
-
-6:	addl	$12, %esp
-	cfi_adjust_cfa_offset(-12)
-	popl	%ebp
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%ebp)
-	popl	%ebx
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%ebx)
-	popl	%esi
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%esi)
-	popl	%edi
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%edi)
-	ret
-
-3:	movl	$EINVAL, %eax
-	ret
-
-	cfi_adjust_cfa_offset(28)
-	cfi_offset(%edi, -8)
-	cfi_offset(%esi, -12)
-	cfi_offset(%ebx, -16)
-	cfi_offset(%ebp, -20)
-	/* Check whether the time expired.  */
-7:	cmpl	$-ETIMEDOUT, %ecx
-	jne	1b
-
-8:	movl	$ETIMEDOUT, %eax
-	jmp	6b
-	cfi_endproc
-	.size	__lll_robust_timedlock_wait,.-__lll_robust_timedlock_wait