x86: Unify rwlock assembly implementation

Rather than having two functionally identical implementations
for 32- and 64-bit configurations, extend the existing assembly
abstractions enough to fold the two rwlock implementations into
a shared one.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4E258DD7020000780004E3EA@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 48 insertions, 84 deletions

diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index f2479f1..d3ed120 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -20,6 +20,7 @@ lib-y := delay.o
 lib-y += thunk_$(BITS).o
 lib-y += usercopy_$(BITS).o getuser.o putuser.o
 lib-y += memcpy_$(BITS).o
+lib-$(CONFIG_SMP) += rwlock.o
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
 
 obj-y += msr.o msr-reg.o msr-reg-export.o
@@ -29,7 +30,8 @@ ifeq ($(CONFIG_X86_32),y)
         lib-y += atomic64_cx8_32.o
         lib-y += checksum_32.o
         lib-y += strstr_32.o
-        lib-y += semaphore_32.o string_32.o
+        lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += semaphore_32.o
+        lib-y += string_32.o
         lib-y += cmpxchg.o
 ifneq ($(CONFIG_X86_CMPXCHG64),y)
         lib-y += cmpxchg8b_emu.o atomic64_386_32.o
@@ -40,7 +42,7 @@ else
         lib-y += csum-partial_64.o csum-copy_64.o csum-wrappers_64.o
         lib-y += thunk_64.o clear_page_64.o copy_page_64.o
         lib-y += memmove_64.o memset_64.o
-        lib-y += copy_user_64.o rwlock_64.o copy_user_nocache_64.o
+        lib-y += copy_user_64.o copy_user_nocache_64.o
 	lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem_64.o
 	lib-y += cmpxchg16b_emu.o
 endif
diff --git a/arch/x86/lib/rwlock.S b/arch/x86/lib/rwlock.S
new file mode 100644
index 0000000..fca1782
--- /dev/null
+++ b/arch/x86/lib/rwlock.S
@@ -0,0 +1,44 @@
+/* Slow paths of read/write spinlocks. */
+
+#include <linux/linkage.h>
+#include <asm/alternative-asm.h>
+#include <asm/frame.h>
+#include <asm/rwlock.h>
+
+#ifdef CONFIG_X86_32
+# define __lock_ptr eax
+#else
+# define __lock_ptr rdi
+#endif
+
+ENTRY(__write_lock_failed)
+	CFI_STARTPROC
+	FRAME
+0:	LOCK_PREFIX
+	addl	$RW_LOCK_BIAS, (%__lock_ptr)
+1:	rep; nop
+	cmpl	$RW_LOCK_BIAS, (%__lock_ptr)
+	jne	1b
+	LOCK_PREFIX
+	subl	$RW_LOCK_BIAS, (%__lock_ptr)
+	jnz	0b
+	ENDFRAME
+	ret
+	CFI_ENDPROC
+END(__write_lock_failed)
+
+ENTRY(__read_lock_failed)
+	CFI_STARTPROC
+	FRAME
+0:	LOCK_PREFIX
+	incl	(%__lock_ptr)
+1:	rep; nop
+	cmpl	$1, (%__lock_ptr)
+	js	1b
+	LOCK_PREFIX
+	decl	(%__lock_ptr)
+	js	0b
+	ENDFRAME
+	ret
+	CFI_ENDPROC
+END(__read_lock_failed)
diff --git a/arch/x86/lib/rwlock_64.S b/arch/x86/lib/rwlock_64.S
deleted file mode 100644
index 05ea55f..0000000
--- a/arch/x86/lib/rwlock_64.S
+++ /dev/null
@@ -1,38 +0,0 @@
-/* Slow paths of read/write spinlocks. */
-
-#include <linux/linkage.h>
-#include <asm/rwlock.h>
-#include <asm/alternative-asm.h>
-#include <asm/dwarf2.h>
-
-/* rdi:	pointer to rwlock_t */
-ENTRY(__write_lock_failed)
-	CFI_STARTPROC
-	LOCK_PREFIX
-	addl $RW_LOCK_BIAS,(%rdi)
-1:	rep
-	nop
-	cmpl $RW_LOCK_BIAS,(%rdi)
-	jne 1b
-	LOCK_PREFIX
-	subl $RW_LOCK_BIAS,(%rdi)
-	jnz  __write_lock_failed
-	ret
-	CFI_ENDPROC
-END(__write_lock_failed)
-
-/* rdi:	pointer to rwlock_t */
-ENTRY(__read_lock_failed)
-	CFI_STARTPROC
-	LOCK_PREFIX
-	incl (%rdi)
-1:	rep
-	nop
-	cmpl $1,(%rdi)
-	js 1b
-	LOCK_PREFIX
-	decl (%rdi)
-	js __read_lock_failed
-	ret
-	CFI_ENDPROC
-END(__read_lock_failed)
diff --git a/arch/x86/lib/semaphore_32.S b/arch/x86/lib/semaphore_32.S
index 06691da..65b591d 100644
--- a/arch/x86/lib/semaphore_32.S
+++ b/arch/x86/lib/semaphore_32.S
@@ -14,8 +14,6 @@
  */
 
 #include <linux/linkage.h>
-#include <asm/rwlock.h>
-#include <asm/alternative-asm.h>
 #include <asm/frame.h>
 #include <asm/dwarf2.h>
 
@@ -31,46 +29,6 @@
  */
 	.section .sched.text, "ax"
 
-/*
- * rw spinlock fallbacks
- */
-#ifdef CONFIG_SMP
-ENTRY(__write_lock_failed)
-	CFI_STARTPROC
-	FRAME
-2: 	LOCK_PREFIX
-	addl	$ RW_LOCK_BIAS,(%eax)
-1:	rep; nop
-	cmpl	$ RW_LOCK_BIAS,(%eax)
-	jne	1b
-	LOCK_PREFIX
-	subl	$ RW_LOCK_BIAS,(%eax)
-	jnz	2b
-	ENDFRAME
-	ret
-	CFI_ENDPROC
-	ENDPROC(__write_lock_failed)
-
-ENTRY(__read_lock_failed)
-	CFI_STARTPROC
-	FRAME
-2: 	LOCK_PREFIX
-	incl	(%eax)
-1:	rep; nop
-	cmpl	$1,(%eax)
-	js	1b
-	LOCK_PREFIX
-	decl	(%eax)
-	js	2b
-	ENDFRAME
-	ret
-	CFI_ENDPROC
-	ENDPROC(__read_lock_failed)
-
-#endif
-
-#ifdef CONFIG_RWSEM_XCHGADD_ALGORITHM
-
 /* Fix up special calling conventions */
 ENTRY(call_rwsem_down_read_failed)
 	CFI_STARTPROC
@@ -120,5 +78,3 @@ ENTRY(call_rwsem_downgrade_wake)
 	ret
 	CFI_ENDPROC
 	ENDPROC(call_rwsem_downgrade_wake)
-
-#endif