diff mbox

[RFC,10/12] x86, rwsem: simplify __down_write

Message ID 20160603161339.GC3693@twins.programming.kicks-ass.net (mailing list archive)
State New, archived
Headers show

Commit Message

Peter Zijlstra June 3, 2016, 4:13 p.m. UTC
On Wed, Feb 03, 2016 at 09:10:16AM +0100, Ingo Molnar wrote:
> 
> * Michal Hocko <mhocko@kernel.org> wrote:
> 
> > From: Michal Hocko <mhocko@suse.com>
> > 
> > x86 implementation of __down_write is using inline asm to optimize the
> > code flow. This however requires that it has go over an additional hop
> > for the slow path call_rwsem_down_write_failed which has to
> > save_common_regs/restore_common_regs to preserve the calling convention.
> > This, however doesn't add much because the fast path only saves one
> > register push/pop (rdx) when compared to the generic implementation:
> > 
> > Before:
> > 0000000000000019 <down_write>:
> >   19:   e8 00 00 00 00          callq  1e <down_write+0x5>
> >   1e:   55                      push   %rbp
> >   1f:   48 ba 01 00 00 00 ff    movabs $0xffffffff00000001,%rdx
> >   26:   ff ff ff
> >   29:   48 89 f8                mov    %rdi,%rax
> >   2c:   48 89 e5                mov    %rsp,%rbp
> >   2f:   f0 48 0f c1 10          lock xadd %rdx,(%rax)
> >   34:   85 d2                   test   %edx,%edx
> >   36:   74 05                   je     3d <down_write+0x24>
> >   38:   e8 00 00 00 00          callq  3d <down_write+0x24>
> >   3d:   65 48 8b 04 25 00 00    mov    %gs:0x0,%rax
> >   44:   00 00
> >   46:   5d                      pop    %rbp
> >   47:   48 89 47 38             mov    %rax,0x38(%rdi)
> >   4b:   c3                      retq
> > 
> > After:
> > 0000000000000019 <down_write>:
> >   19:   e8 00 00 00 00          callq  1e <down_write+0x5>
> >   1e:   55                      push   %rbp
> >   1f:   48 b8 01 00 00 00 ff    movabs $0xffffffff00000001,%rax
> >   26:   ff ff ff
> >   29:   48 89 e5                mov    %rsp,%rbp
> >   2c:   53                      push   %rbx
> >   2d:   48 89 fb                mov    %rdi,%rbx
> >   30:   f0 48 0f c1 07          lock xadd %rax,(%rdi)
> >   35:   48 85 c0                test   %rax,%rax
> >   38:   74 05                   je     3f <down_write+0x26>
> >   3a:   e8 00 00 00 00          callq  3f <down_write+0x26>
> >   3f:   65 48 8b 04 25 00 00    mov    %gs:0x0,%rax
> >   46:   00 00
> >   48:   48 89 43 38             mov    %rax,0x38(%rbx)
> >   4c:   5b                      pop    %rbx
> >   4d:   5d                      pop    %rbp
> >   4e:   c3                      retq
> 
> I'm not convinced about the removal of this optimization at all.

So I've been playing with this again because Jason's atomic_long_t
patches made a mess of things.

(similar findings for both ia64 and s390, suggesting killing all
arch/*/include/asm/rwsem.h might actuyally be an option).

Here's what I get (gcc-5.3.0):

# size x86_64-defconfig/vmlinux.{orig,mod}
   text    data     bss     dec     hex filename
10193229        4340512 1105920 15639661         eea46d x86_64-defconfig/vmlinux.orig
10193101        4340512 1105920 15639533         eea3ed x86_64-defconfig/vmlinux.mod

# objdump -D x86_64-defconfig/vmlinux.orig | awk '/<[^>]*>:$/ { p=0; } /<down_write>:/ { p=1; } { if (p) print $0; }'
ffffffff818d0d80 <down_write>:
ffffffff818d0d80:       55                      push   %rbp
ffffffff818d0d81:       48 89 e5                mov    %rsp,%rbp
ffffffff818d0d84:       53                      push   %rbx
ffffffff818d0d85:       48 89 fb                mov    %rdi,%rbx
ffffffff818d0d88:       e8 33 e3 ff ff          callq  ffffffff818cf0c0 <_cond_resched>
ffffffff818d0d8d:       48 ba 01 00 00 00 ff    movabs $0xffffffff00000001,%rdx
ffffffff818d0d94:       ff ff ff 
ffffffff818d0d97:       48 89 d8                mov    %rbx,%rax
ffffffff818d0d9a:       f0 48 0f c1 10          lock xadd %rdx,(%rax)
ffffffff818d0d9f:       85 d2                   test   %edx,%edx
ffffffff818d0da1:       74 05                   je     ffffffff818d0da8 <down_write+0x28>
ffffffff818d0da3:       e8 b8 d0 a5 ff          callq  ffffffff8132de60 <call_rwsem_down_write_failed>
ffffffff818d0da8:       65 48 8b 04 25 00 c4    mov    %gs:0xc400,%rax
ffffffff818d0daf:       00 00 
ffffffff818d0db1:       48 89 43 20             mov    %rax,0x20(%rbx)
ffffffff818d0db5:       5b                      pop    %rbx
ffffffff818d0db6:       5d                      pop    %rbp
ffffffff818d0db7:       c3                      retq   
ffffffff818d0db8:       0f 1f 84 00 00 00 00    nopl   0x0(%rax,%rax,1)
ffffffff818d0dbf:       00 

^C
# objdump -D x86_64-defconfig/vmlinux.mod | awk '/<[^>]*>:$/ { p=0; } /<down_write>:/ { p=1; } { if (p) print $0; }'
ffffffff818d0cf0 <down_write>:
ffffffff818d0cf0:       55                      push   %rbp
ffffffff818d0cf1:       48 89 e5                mov    %rsp,%rbp
ffffffff818d0cf4:       53                      push   %rbx
ffffffff818d0cf5:       48 89 fb                mov    %rdi,%rbx
ffffffff818d0cf8:       e8 23 e3 ff ff          callq  ffffffff818cf020 <_cond_resched>
ffffffff818d0cfd:       48 b8 01 00 00 00 ff    movabs $0xffffffff00000001,%rax
ffffffff818d0d04:       ff ff ff 
ffffffff818d0d07:       f0 48 0f c1 03          lock xadd %rax,(%rbx)
ffffffff818d0d0c:       48 85 c0                test   %rax,%rax
ffffffff818d0d0f:       75 10                   jne    ffffffff818d0d21 <down_write+0x31>
ffffffff818d0d11:       65 48 8b 04 25 00 c4    mov    %gs:0xc400,%rax
ffffffff818d0d18:       00 00 
ffffffff818d0d1a:       48 89 43 20             mov    %rax,0x20(%rbx)
ffffffff818d0d1e:       5b                      pop    %rbx
ffffffff818d0d1f:       5d                      pop    %rbp
ffffffff818d0d20:       c3                      retq   
ffffffff818d0d21:       48 89 df                mov    %rbx,%rdi
ffffffff818d0d24:       e8 f7 06 00 00          callq  ffffffff818d1420 <rwsem_down_write_failed>
ffffffff818d0d29:       eb e6                   jmp    ffffffff818d0d11 <down_write+0x21>
ffffffff818d0d2b:       0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)

---

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Comments

Peter Zijlstra June 3, 2016, 10:34 p.m. UTC | #1
On Fri, Jun 03, 2016 at 06:13:39PM +0200, Peter Zijlstra wrote:
> So I've been playing with this again because Jason's atomic_long_t
> patches made a mess of things.
> 
> (similar findings for both ia64 and s390, suggesting killing all
> arch/*/include/asm/rwsem.h might actuyally be an option).
> 

Blergh; so looking at more asm there's still a few tricks we cannot do.
So while overall size is down, some paths do end up more expensive. (It
typically boils down to creative use of condition flags, which is very
hard in C)
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David Howells June 9, 2016, 2:40 p.m. UTC | #2
Peter Zijlstra <peterz@infradead.org> wrote:

> Blergh; so looking at more asm there's still a few tricks we cannot do.
> So while overall size is down, some paths do end up more expensive. (It
> typically boils down to creative use of condition flags, which is very
> hard in C)

It can be done using ISO __atomic_fetch_add() and suchlike.

David
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Peter Zijlstra June 9, 2016, 5:36 p.m. UTC | #3
On Thu, Jun 09, 2016 at 03:40:58PM +0100, David Howells wrote:
> Peter Zijlstra <peterz@infradead.org> wrote:
> 
> > Blergh; so looking at more asm there's still a few tricks we cannot do.
> > So while overall size is down, some paths do end up more expensive. (It
> > typically boils down to creative use of condition flags, which is very
> > hard in C)
> 
> It can be done using ISO __atomic_fetch_add() and suchlike.

(ISO-C11, ISO as such is a bad abbreviation I think)

Maybe, but we're almost there with __GCC_ASM_FLAG_OUTPUTS__.

atomic_long_add_negative() can be made to do inc;j(n)s for __down_read.

the try_cmpxchg family you wanted to add independent from the ISO-C11
bits can do the cmpxchg-j(n)z for __down_{read,write}_trylock.

That only leaves us wanting an atomic_long_fetch_add_negative() for
__up_{read,write}().

Although I suppose, for this to be of use for our weakly ordered
friends, we need _relaxed versions of all that (so that _acquire and
_release variants are generated).


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Paul E. McKenney June 10, 2016, 4:39 p.m. UTC | #4
On Thu, Jun 09, 2016 at 07:36:40PM +0200, Peter Zijlstra wrote:
> On Thu, Jun 09, 2016 at 03:40:58PM +0100, David Howells wrote:
> > Peter Zijlstra <peterz@infradead.org> wrote:
> > 
> > > Blergh; so looking at more asm there's still a few tricks we cannot do.
> > > So while overall size is down, some paths do end up more expensive. (It
> > > typically boils down to creative use of condition flags, which is very
> > > hard in C)
> > 
> > It can be done using ISO __atomic_fetch_add() and suchlike.
> 
> (ISO-C11, ISO as such is a bad abbreviation I think)
> 
> Maybe, but we're almost there with __GCC_ASM_FLAG_OUTPUTS__.
> 
> atomic_long_add_negative() can be made to do inc;j(n)s for __down_read.
> 
> the try_cmpxchg family you wanted to add independent from the ISO-C11
> bits can do the cmpxchg-j(n)z for __down_{read,write}_trylock.
> 
> That only leaves us wanting an atomic_long_fetch_add_negative() for
> __up_{read,write}().
> 
> Although I suppose, for this to be of use for our weakly ordered
> friends, we need _relaxed versions of all that (so that _acquire and
> _release variants are generated).

Historically, the compilers have won this sort of contest over the
long term.  That said, there is nothing quite like raising the bar for
them to help them generate decent code.  So, David and Peter, I am behind
both of you 100%.  ;-)

							Thanx, Paul

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diff mbox

Patch

diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index aeac434..1262556 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -10,3 +10,4 @@  generic-y += dma-contiguous.h
 generic-y += early_ioremap.h
 generic-y += mcs_spinlock.h
 generic-y += mm-arch-hooks.h
+generic-y += rwsem.h
diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
deleted file mode 100644
index 089ced4..0000000
--- a/arch/x86/include/asm/rwsem.h
+++ /dev/null
@@ -1,217 +0,0 @@ 
-/* rwsem.h: R/W semaphores implemented using XADD/CMPXCHG for i486+
- *
- * Written by David Howells (dhowells@redhat.com).
- *
- * Derived from asm-x86/semaphore.h
- *
- *
- * The MSW of the count is the negated number of active writers and waiting
- * lockers, and the LSW is the total number of active locks
- *
- * The lock count is initialized to 0 (no active and no waiting lockers).
- *
- * When a writer subtracts WRITE_BIAS, it'll get 0xffff0001 for the case of an
- * uncontended lock. This can be determined because XADD returns the old value.
- * Readers increment by 1 and see a positive value when uncontended, negative
- * if there are writers (and maybe) readers waiting (in which case it goes to
- * sleep).
- *
- * The value of WAITING_BIAS supports up to 32766 waiting processes. This can
- * be extended to 65534 by manually checking the whole MSW rather than relying
- * on the S flag.
- *
- * The value of ACTIVE_BIAS supports up to 65535 active processes.
- *
- * This should be totally fair - if anything is waiting, a process that wants a
- * lock will go to the back of the queue. When the currently active lock is
- * released, if there's a writer at the front of the queue, then that and only
- * that will be woken up; if there's a bunch of consecutive readers at the
- * front, then they'll all be woken up, but no other readers will be.
- */
-
-#ifndef _ASM_X86_RWSEM_H
-#define _ASM_X86_RWSEM_H
-
-#ifndef _LINUX_RWSEM_H
-#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
-#endif
-
-#ifdef __KERNEL__
-#include <asm/asm.h>
-
-/*
- * The bias values and the counter type limits the number of
- * potential readers/writers to 32767 for 32 bits and 2147483647
- * for 64 bits.
- */
-
-#ifdef CONFIG_X86_64
-# define RWSEM_ACTIVE_MASK		0xffffffffL
-#else
-# define RWSEM_ACTIVE_MASK		0x0000ffffL
-#endif
-
-#define RWSEM_UNLOCKED_VALUE		0x00000000L
-#define RWSEM_ACTIVE_BIAS		0x00000001L
-#define RWSEM_WAITING_BIAS		(-RWSEM_ACTIVE_MASK-1)
-#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
-#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
-
-/*
- * lock for reading
- */
-static inline void __down_read(struct rw_semaphore *sem)
-{
-	asm volatile("# beginning down_read\n\t"
-		     LOCK_PREFIX _ASM_INC "(%1)\n\t"
-		     /* adds 0x00000001 */
-		     "  jns        1f\n"
-		     "  call call_rwsem_down_read_failed\n"
-		     "1:\n\t"
-		     "# ending down_read\n\t"
-		     : "+m" (sem->count)
-		     : "a" (sem)
-		     : "memory", "cc");
-}
-
-/*
- * trylock for reading -- returns 1 if successful, 0 if contention
- */
-static inline int __down_read_trylock(struct rw_semaphore *sem)
-{
-	long result, tmp;
-	asm volatile("# beginning __down_read_trylock\n\t"
-		     "  mov          %0,%1\n\t"
-		     "1:\n\t"
-		     "  mov          %1,%2\n\t"
-		     "  add          %3,%2\n\t"
-		     "  jle	     2f\n\t"
-		     LOCK_PREFIX "  cmpxchg  %2,%0\n\t"
-		     "  jnz	     1b\n\t"
-		     "2:\n\t"
-		     "# ending __down_read_trylock\n\t"
-		     : "+m" (sem->count), "=&a" (result), "=&r" (tmp)
-		     : "i" (RWSEM_ACTIVE_READ_BIAS)
-		     : "memory", "cc");
-	return result >= 0 ? 1 : 0;
-}
-
-/*
- * lock for writing
- */
-#define ____down_write(sem, slow_path)			\
-({							\
-	long tmp;					\
-	struct rw_semaphore* ret;			\
-	asm volatile("# beginning down_write\n\t"	\
-		     LOCK_PREFIX "  xadd      %1,(%3)\n\t"	\
-		     /* adds 0xffff0001, returns the old value */ \
-		     "  test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" \
-		     /* was the active mask 0 before? */\
-		     "  jz        1f\n"			\
-		     "  call " slow_path "\n"		\
-		     "1:\n"				\
-		     "# ending down_write"		\
-		     : "+m" (sem->count), "=d" (tmp), "=a" (ret)	\
-		     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \
-		     : "memory", "cc");			\
-	ret;						\
-})
-
-static inline void __down_write(struct rw_semaphore *sem)
-{
-	____down_write(sem, "call_rwsem_down_write_failed");
-}
-
-static inline int __down_write_killable(struct rw_semaphore *sem)
-{
-	if (IS_ERR(____down_write(sem, "call_rwsem_down_write_failed_killable")))
-		return -EINTR;
-
-	return 0;
-}
-
-/*
- * trylock for writing -- returns 1 if successful, 0 if contention
- */
-static inline int __down_write_trylock(struct rw_semaphore *sem)
-{
-	long result, tmp;
-	asm volatile("# beginning __down_write_trylock\n\t"
-		     "  mov          %0,%1\n\t"
-		     "1:\n\t"
-		     "  test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t"
-		     /* was the active mask 0 before? */
-		     "  jnz          2f\n\t"
-		     "  mov          %1,%2\n\t"
-		     "  add          %3,%2\n\t"
-		     LOCK_PREFIX "  cmpxchg  %2,%0\n\t"
-		     "  jnz	     1b\n\t"
-		     "2:\n\t"
-		     "  sete         %b1\n\t"
-		     "  movzbl       %b1, %k1\n\t"
-		     "# ending __down_write_trylock\n\t"
-		     : "+m" (sem->count), "=&a" (result), "=&r" (tmp)
-		     : "er" (RWSEM_ACTIVE_WRITE_BIAS)
-		     : "memory", "cc");
-	return result;
-}
-
-/*
- * unlock after reading
- */
-static inline void __up_read(struct rw_semaphore *sem)
-{
-	long tmp;
-	asm volatile("# beginning __up_read\n\t"
-		     LOCK_PREFIX "  xadd      %1,(%2)\n\t"
-		     /* subtracts 1, returns the old value */
-		     "  jns        1f\n\t"
-		     "  call call_rwsem_wake\n" /* expects old value in %edx */
-		     "1:\n"
-		     "# ending __up_read\n"
-		     : "+m" (sem->count), "=d" (tmp)
-		     : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS)
-		     : "memory", "cc");
-}
-
-/*
- * unlock after writing
- */
-static inline void __up_write(struct rw_semaphore *sem)
-{
-	long tmp;
-	asm volatile("# beginning __up_write\n\t"
-		     LOCK_PREFIX "  xadd      %1,(%2)\n\t"
-		     /* subtracts 0xffff0001, returns the old value */
-		     "  jns        1f\n\t"
-		     "  call call_rwsem_wake\n" /* expects old value in %edx */
-		     "1:\n\t"
-		     "# ending __up_write\n"
-		     : "+m" (sem->count), "=d" (tmp)
-		     : "a" (sem), "1" (-RWSEM_ACTIVE_WRITE_BIAS)
-		     : "memory", "cc");
-}
-
-/*
- * downgrade write lock to read lock
- */
-static inline void __downgrade_write(struct rw_semaphore *sem)
-{
-	asm volatile("# beginning __downgrade_write\n\t"
-		     LOCK_PREFIX _ASM_ADD "%2,(%1)\n\t"
-		     /*
-		      * transitions 0xZZZZ0001 -> 0xYYYY0001 (i386)
-		      *     0xZZZZZZZZ00000001 -> 0xYYYYYYYY00000001 (x86_64)
-		      */
-		     "  jns       1f\n\t"
-		     "  call call_rwsem_downgrade_wake\n"
-		     "1:\n\t"
-		     "# ending __downgrade_write\n"
-		     : "+m" (sem->count)
-		     : "a" (sem), "er" (-RWSEM_WAITING_BIAS)
-		     : "memory", "cc");
-}
-
-#endif /* __KERNEL__ */
-#endif /* _ASM_X86_RWSEM_H */
diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 72a5767..c47dd5f 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -22,7 +22,6 @@  obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
 lib-y := delay.o misc.o cmdline.o cpu.o
 lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
 lib-y += memcpy_$(BITS).o
-lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
 
 obj-y += msr.o msr-reg.o msr-reg-export.o
diff --git a/arch/x86/lib/rwsem.S b/arch/x86/lib/rwsem.S
deleted file mode 100644
index bf2c607..0000000
--- a/arch/x86/lib/rwsem.S
+++ /dev/null
@@ -1,144 +0,0 @@ 
-/*
- * x86 semaphore implementation.
- *
- * (C) Copyright 1999 Linus Torvalds
- *
- * Portions Copyright 1999 Red Hat, Inc.
- *
- *	This program is free software; you can redistribute it and/or
- *	modify it under the terms of the GNU General Public License
- *	as published by the Free Software Foundation; either version
- *	2 of the License, or (at your option) any later version.
- *
- * rw semaphores implemented November 1999 by Benjamin LaHaise <bcrl@kvack.org>
- */
-
-#include <linux/linkage.h>
-#include <asm/alternative-asm.h>
-#include <asm/frame.h>
-
-#define __ASM_HALF_REG(reg)	__ASM_SEL(reg, e##reg)
-#define __ASM_HALF_SIZE(inst)	__ASM_SEL(inst##w, inst##l)
-
-#ifdef CONFIG_X86_32
-
-/*
- * The semaphore operations have a special calling sequence that
- * allow us to do a simpler in-line version of them. These routines
- * need to convert that sequence back into the C sequence when
- * there is contention on the semaphore.
- *
- * %eax contains the semaphore pointer on entry. Save the C-clobbered
- * registers (%eax, %edx and %ecx) except %eax which is either a return
- * value or just gets clobbered. Same is true for %edx so make sure GCC
- * reloads it after the slow path, by making it hold a temporary, for
- * example see ____down_write().
- */
-
-#define save_common_regs \
-	pushl %ecx
-
-#define restore_common_regs \
-	popl %ecx
-
-	/* Avoid uglifying the argument copying x86-64 needs to do. */
-	.macro movq src, dst
-	.endm
-
-#else
-
-/*
- * x86-64 rwsem wrappers
- *
- * This interfaces the inline asm code to the slow-path
- * C routines. We need to save the call-clobbered regs
- * that the asm does not mark as clobbered, and move the
- * argument from %rax to %rdi.
- *
- * NOTE! We don't need to save %rax, because the functions
- * will always return the semaphore pointer in %rax (which
- * is also the input argument to these helpers)
- *
- * The following can clobber %rdx because the asm clobbers it:
- *   call_rwsem_down_write_failed
- *   call_rwsem_wake
- * but %rdi, %rsi, %rcx, %r8-r11 always need saving.
- */
-
-#define save_common_regs \
-	pushq %rdi; \
-	pushq %rsi; \
-	pushq %rcx; \
-	pushq %r8;  \
-	pushq %r9;  \
-	pushq %r10; \
-	pushq %r11
-
-#define restore_common_regs \
-	popq %r11; \
-	popq %r10; \
-	popq %r9; \
-	popq %r8; \
-	popq %rcx; \
-	popq %rsi; \
-	popq %rdi
-
-#endif
-
-/* Fix up special calling conventions */
-ENTRY(call_rwsem_down_read_failed)
-	FRAME_BEGIN
-	save_common_regs
-	__ASM_SIZE(push,) %__ASM_REG(dx)
-	movq %rax,%rdi
-	call rwsem_down_read_failed
-	__ASM_SIZE(pop,) %__ASM_REG(dx)
-	restore_common_regs
-	FRAME_END
-	ret
-ENDPROC(call_rwsem_down_read_failed)
-
-ENTRY(call_rwsem_down_write_failed)
-	FRAME_BEGIN
-	save_common_regs
-	movq %rax,%rdi
-	call rwsem_down_write_failed
-	restore_common_regs
-	FRAME_END
-	ret
-ENDPROC(call_rwsem_down_write_failed)
-
-ENTRY(call_rwsem_down_write_failed_killable)
-	FRAME_BEGIN
-	save_common_regs
-	movq %rax,%rdi
-	call rwsem_down_write_failed_killable
-	restore_common_regs
-	FRAME_END
-	ret
-ENDPROC(call_rwsem_down_write_failed_killable)
-
-ENTRY(call_rwsem_wake)
-	FRAME_BEGIN
-	/* do nothing if still outstanding active readers */
-	__ASM_HALF_SIZE(dec) %__ASM_HALF_REG(dx)
-	jnz 1f
-	save_common_regs
-	movq %rax,%rdi
-	call rwsem_wake
-	restore_common_regs
-1:	FRAME_END
-	ret
-ENDPROC(call_rwsem_wake)
-
-ENTRY(call_rwsem_downgrade_wake)
-	FRAME_BEGIN
-	save_common_regs
-	__ASM_SIZE(push,) %__ASM_REG(dx)
-	movq %rax,%rdi
-	call rwsem_downgrade_wake
-	__ASM_SIZE(pop,) %__ASM_REG(dx)
-	restore_common_regs
-	FRAME_END
-	ret
-ENDPROC(call_rwsem_downgrade_wake)