nptl: Assume __ASSUME_FUTEX_CLOCK_REALTIME support
diff mbox series

Message ID 20190228172110.15833-1-adhemerval.zanella@linaro.org
State New
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Series
  • nptl: Assume __ASSUME_FUTEX_CLOCK_REALTIME support
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Commit Message

Adhemerval Zanella Feb. 28, 2019, 5:21 p.m. UTC
This patch assumes realtime clock support for nptl and thus removes
all the associated code.

For __pthread_mutex_timedlock the fallback usage for the case where
lll_futex_timed_wait_bitset it not set define is also removed. The
generic lowlevellock-futex.h always define it, so for NPTL code the
check always yield true.

Checked on x86_64-linux-gnu and i686-linux-gnu.

	* nptl/nptl-init.c (__have_futex_clock_realtime,
	__have_futex_clock_realtime): Remove definition.
	(__pthread_initialize_minimal_internal): Remove FUTEX_CLOCK_REALTIME
	check test for !__ASSUME_FUTEX_CLOCK_REALTIME.
	* nptl/pthread_mutex_timedlock.c (__pthread_mutex_timedlock): Assume
	__ASSUME_FUTEX_CLOCK_REALTIME support.
	* sysdeps/unix/sysv/linux/i386/lowlevellock.S: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/lowlevellock.S: Likewise.
	* sysdeps/unix/sysv/linux/kernel-features.h
	(__ASSUME_FUTEX_CLOCK_REALTIME): Remove.
	* sysdeps/nptl/lowlevellock-futex.h (lll_futex_timed_wait_bitset):
	Adjust comment.
---
 nptl/nptl-init.c                              |  29 -----
 nptl/pthread_mutex_timedlock.c                |  27 ----
 sysdeps/nptl/lowlevellock-futex.h             |   3 +-
 sysdeps/unix/sysv/linux/i386/lowlevellock.S   | 100 ---------------
 sysdeps/unix/sysv/linux/kernel-features.h     |   3 -
 sysdeps/unix/sysv/linux/x86_64/lowlevellock.S | 115 ------------------
 6 files changed, 1 insertion(+), 276 deletions(-)

Comments

Florian Weimer March 5, 2019, 11:42 a.m. UTC | #1
* Adhemerval Zanella:

> This patch assumes realtime clock support for nptl and thus removes
> all the associated code.
>
> For __pthread_mutex_timedlock the fallback usage for the case where
> lll_futex_timed_wait_bitset it not set define is also removed. The
> generic lowlevellock-futex.h always define it, so for NPTL code the
> check always yield true.
>
> Checked on x86_64-linux-gnu and i686-linux-gnu.
>
> 	* nptl/nptl-init.c (__have_futex_clock_realtime,
> 	__have_futex_clock_realtime): Remove definition.
> 	(__pthread_initialize_minimal_internal): Remove FUTEX_CLOCK_REALTIME
> 	check test for !__ASSUME_FUTEX_CLOCK_REALTIME.
> 	* nptl/pthread_mutex_timedlock.c (__pthread_mutex_timedlock): Assume
> 	__ASSUME_FUTEX_CLOCK_REALTIME support.
> 	* sysdeps/unix/sysv/linux/i386/lowlevellock.S: Likewise.
> 	* sysdeps/unix/sysv/linux/x86_64/lowlevellock.S: Likewise.
> 	* sysdeps/unix/sysv/linux/kernel-features.h
> 	(__ASSUME_FUTEX_CLOCK_REALTIME): Remove.
> 	* sysdeps/nptl/lowlevellock-futex.h (lll_futex_timed_wait_bitset):
> 	Adjust comment.

Patch looks good to me.  Thanks.

Florian

Patch
diff mbox series

diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index b5895fabf3..61ec8ed12a 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -58,15 +58,6 @@  int __set_robust_list_avail;
 # define set_robust_list_not_avail() do { } while (0)
 #endif
 
-#ifndef __ASSUME_FUTEX_CLOCK_REALTIME
-/* Nonzero if we do not have FUTEX_CLOCK_REALTIME.  */
-int __have_futex_clock_realtime;
-# define __set_futex_clock_realtime() \
-  __have_futex_clock_realtime = 1
-#else
-#define __set_futex_clock_realtime() do { } while (0)
-#endif
-
 /* Version of the library, used in libthread_db to detect mismatches.  */
 static const char nptl_version[] __attribute_used__ = VERSION;
 
@@ -298,26 +289,6 @@  __pthread_initialize_minimal_internal (void)
       set_robust_list_not_avail ();
   }
 
-#ifdef __NR_futex
-# ifndef __ASSUME_FUTEX_CLOCK_REALTIME
-    {
-      int word = 0;
-      /* NB: the syscall actually takes six parameters.  The last is the
-	 bit mask.  But since we will not actually wait at all the value
-	 is irrelevant.  Given that passing six parameters is difficult
-	 on some architectures we just pass whatever random value the
-	 calling convention calls for to the kernel.  It causes no harm.  */
-      INTERNAL_SYSCALL_DECL (err);
-      word = INTERNAL_SYSCALL (futex, err, 5, &word,
-			       FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME
-			       | FUTEX_PRIVATE_FLAG, 1, NULL, 0);
-      assert (INTERNAL_SYSCALL_ERROR_P (word, err));
-      if (INTERNAL_SYSCALL_ERRNO (word, err) != ENOSYS)
-	__set_futex_clock_realtime ();
-    }
-# endif
-#endif
-
   /* Set initial thread's stack block from 0 up to __libc_stack_end.
      It will be bigger than it actually is, but for unwind.c/pt-longjmp.c
      purposes this is good enough.  */
diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c
index 2f61a7d0d5..270b072c97 100644
--- a/nptl/pthread_mutex_timedlock.c
+++ b/nptl/pthread_mutex_timedlock.c
@@ -240,27 +240,6 @@  __pthread_mutex_timedlock (pthread_mutex_t *mutex,
 	     values despite them being valid.  */
 	  if (__glibc_unlikely (abstime->tv_sec < 0))
 	    return ETIMEDOUT;
-#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
-     || !defined lll_futex_timed_wait_bitset)
-	  struct timeval tv;
-	  struct timespec rt;
-
-	  /* Get the current time.  */
-	  (void) __gettimeofday (&tv, NULL);
-
-	  /* Compute relative timeout.  */
-	  rt.tv_sec = abstime->tv_sec - tv.tv_sec;
-	  rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
-	  if (rt.tv_nsec < 0)
-	    {
-	      rt.tv_nsec += 1000000000;
-	      --rt.tv_sec;
-	    }
-
-	  /* Already timed out?  */
-	  if (rt.tv_sec < 0)
-	    return ETIMEDOUT;
-#endif
 
 	  /* We cannot acquire the mutex nor has its owner died.  Thus, try
 	     to block using futexes.  Set FUTEX_WAITERS if necessary so that
@@ -287,18 +266,12 @@  __pthread_mutex_timedlock (pthread_mutex_t *mutex,
 	  assume_other_futex_waiters |= FUTEX_WAITERS;
 
 	  /* Block using the futex.  */
-#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
-     || !defined lll_futex_timed_wait_bitset)
-	  lll_futex_timed_wait (&mutex->__data.__lock, oldval,
-				&rt, PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
-#else
 	  int err = lll_futex_timed_wait_bitset (&mutex->__data.__lock,
 	      oldval, abstime, FUTEX_CLOCK_REALTIME,
 	      PTHREAD_ROBUST_MUTEX_PSHARED (mutex));
 	  /* The futex call timed out.  */
 	  if (err == -ETIMEDOUT)
 	    return -err;
-#endif
 	  /* Reload current lock value.  */
 	  oldval = mutex->__data.__lock;
 	}
diff --git a/sysdeps/nptl/lowlevellock-futex.h b/sysdeps/nptl/lowlevellock-futex.h
index bb8effe288..63d917d8da 100644
--- a/sysdeps/nptl/lowlevellock-futex.h
+++ b/sysdeps/nptl/lowlevellock-futex.h
@@ -43,8 +43,7 @@ 
 #define lll_futex_timed_wait(futexp, val, timeout, private)             \
   -ENOSYS
 
-/* This macro should be defined only if FUTEX_CLOCK_REALTIME is also defined.
-   If CLOCKBIT is zero, this is identical to lll_futex_timed_wait.
+/* If CLOCKBIT is zero, this is identical to lll_futex_timed_wait.
    If CLOCKBIT has FUTEX_CLOCK_REALTIME set, then it's the same but
    TIMEOUT is counted by CLOCK_REALTIME rather than CLOCK_MONOTONIC.  */
 #define lll_futex_timed_wait_bitset(futexp, val, timeout, clockbit, private) \
diff --git a/sysdeps/unix/sysv/linux/i386/lowlevellock.S b/sysdeps/unix/sysv/linux/i386/lowlevellock.S
index 83191a3899..a9898e94fd 100644
--- a/sysdeps/unix/sysv/linux/i386/lowlevellock.S
+++ b/sysdeps/unix/sysv/linux/i386/lowlevellock.S
@@ -148,16 +148,6 @@  __lll_timedlock_wait:
 	cfi_adjust_cfa_offset(4)
 	cfi_rel_offset(%ebx, 0)
 
-# ifndef __ASSUME_FUTEX_CLOCK_REALTIME
-#  ifdef PIC
-	LOAD_PIC_REG (bx)
-	cmpl	$0, __have_futex_clock_realtime@GOTOFF(%ebx)
-#  else
-	cmpl	$0, __have_futex_clock_realtime
-#  endif
-	je	.Lreltmo
-# endif
-
 	cmpl	$0, (%edx)
 	js	8f
 
@@ -199,96 +189,6 @@  __lll_timedlock_wait:
 8:	movl	$ETIMEDOUT, %eax
 	jmp	7b
 
-# ifndef __ASSUME_FUTEX_CLOCK_REALTIME
-.Lreltmo:
-	/* Check for a valid timeout value.  */
-	cmpl	$1000000000, 4(%edx)
-	jae	3f
-
-	pushl	%esi
-	cfi_adjust_cfa_offset(4)
-	cfi_rel_offset(%esi, 0)
-	pushl	%edi
-	cfi_adjust_cfa_offset(4)
-	cfi_rel_offset(%edi, 0)
-
-	/* Stack frame for the timespec and timeval structs.  */
-	subl	$8, %esp
-	cfi_adjust_cfa_offset(8)
-
-	movl	%ecx, %ebp
-	movl	%edx, %edi
-
-	movl	$2, %edx
-	xchgl	%edx, (%ebp)
-
-	test	%edx, %edx
-	je	6f
-
-1:
-	/* 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	2f		/* Time is already up.  */
-
-	/* Store relative timeout.  */
-	movl	%ecx, (%esp)
-	movl	%edx, 4(%esp)
-
-	/* Futex call.  */
-	movl	%ebp, %ebx
-	movl	$2, %edx
-	movl	%esp, %esi
-	movl	16(%esp), %ecx
-	LOAD_FUTEX_WAIT (%ecx)
-	movl	$SYS_futex, %eax
-	ENTER_KERNEL
-
-	/* NB: %edx == 2 */
-	xchgl	%edx, (%ebp)
-
-	testl	%edx, %edx
-	je	6f
-
-	cmpl	$-ETIMEDOUT, %eax
-	jne	1b
-2:	movl	$ETIMEDOUT, %edx
-
-6:	addl	$8, %esp
-	cfi_adjust_cfa_offset(-8)
-	popl	%edi
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%edi)
-	popl	%esi
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%esi)
-7:	popl	%ebx
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%ebx)
-	popl	%ebp
-	cfi_adjust_cfa_offset(-4)
-	cfi_restore(%ebp)
-	movl	%edx, %eax
-	ret
-
-3:	movl	$EINVAL, %edx
-	jmp	7b
-# endif
 	cfi_endproc
 	.size	__lll_timedlock_wait,.-__lll_timedlock_wait
 #endif
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index 0db1b987a4..bc5c959f58 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -57,9 +57,6 @@ 
    2.6.27.  */
 #define __ASSUME_IN_NONBLOCK	1
 
-/* Support for the FUTEX_CLOCK_REALTIME flag was added in 2.6.29.  */
-#define __ASSUME_FUTEX_CLOCK_REALTIME	1
-
 /* Support for preadv and pwritev was added in 2.6.30.  */
 #define __ASSUME_PREADV	1
 #define __ASSUME_PWRITEV	1
diff --git a/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S b/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S
index 166dbcfd3b..00ba88d5d2 100644
--- a/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S
+++ b/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S
@@ -127,15 +127,6 @@  __lll_lock_wait:
 	.align	16
 __lll_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	5f
 
@@ -176,112 +167,6 @@  __lll_timedlock_wait:
 5:	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)
-	pushq	%r14
-	cfi_adjust_cfa_offset(8)
-	cfi_offset(%r8, -16)
-	cfi_offset(%r9, -24)
-	cfi_offset(%r12, -32)
-	cfi_offset(%r13, -40)
-	cfi_offset(%r14, -48)
-	pushq	%rsi
-	cfi_adjust_cfa_offset(8)
-
-	/* Stack frame for the timespec and timeval structs.  */
-	subq	$24, %rsp
-	cfi_adjust_cfa_offset(24)
-
-	movq	%rdi, %r12
-	movq	%rdx, %r13
-
-	movl	$2, %edx
-	xchgl	%edx, (%r12)
-
-	testl	%edx, %edx
-	je	6f
-
-1:
-	/* 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	2f		/* Time is already up.  */
-
-	/* Store relative timeout.  */
-	movq	%rdi, (%rsp)
-	movq	%rsi, 8(%rsp)
-
-	/* Futex call.  */
-	movl	$2, %edx
-	movl	$1, %eax
-	movq	%rsp, %r10
-	movl	24(%rsp), %esi
-	LOAD_FUTEX_WAIT (%esi)
-	movq	%r12, %rdi
-	movl	$SYS_futex, %eax
-	syscall
-
-	/* NB: %edx == 2 */
-	xchgl	%edx, (%r12)
-
-	testl	%edx, %edx
-	je	6f
-
-	cmpl	$-ETIMEDOUT, %eax
-	jne	1b
-2:	movl	$ETIMEDOUT, %edx
-
-6:	addq	$32, %rsp
-	cfi_adjust_cfa_offset(-32)
-	popq	%r14
-	cfi_adjust_cfa_offset(-8)
-	cfi_restore(%r14)
-	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)
-	movl	%edx, %eax
-	retq
-
-3:	movl	$EINVAL, %eax
-	retq
-# endif
 	cfi_endproc
 	.size	__lll_timedlock_wait,.-__lll_timedlock_wait
 #endif