x86: Unify rwsem assembly implementation

Rather than having two functionally identical implementations
for 32- and 64-bit configurations, use the previously extended
assembly abstractions to fold the rwsem two 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/4E258DF3020000780004E3ED@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/um/sys-i386/Makefile

@@ -8,7 +8,7 @@ obj-y = bug.o bugs.o checksum.o delay.o fault.o ksyms.o ldt.o ptrace.o \
 
 obj-$(CONFIG_BINFMT_ELF) += elfcore.o
 
-subarch-obj-y = lib/semaphore_32.o lib/string_32.o
+subarch-obj-y = lib/rwsem.o lib/string_32.o
 subarch-obj-$(CONFIG_HIGHMEM) += mm/highmem_32.o
 subarch-obj-$(CONFIG_MODULES) += kernel/module.o
 

arch/um/sys-x86_64/Makefile

@@ -9,7 +9,7 @@ obj-y = bug.o bugs.o delay.o fault.o ldt.o mem.o ptrace.o ptrace_user.o \
 	sysrq.o ksyms.o tls.o
 
 subarch-obj-y = lib/csum-partial_64.o lib/memcpy_64.o lib/thunk_64.o \
-		lib/rwsem_64.o
+		lib/rwsem.o
 subarch-obj-$(CONFIG_MODULES) += kernel/module.o
 
 ldt-y = ../sys-i386/ldt.o

arch/x86/lib/Makefile

@@ -21,6 +21,7 @@ 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-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem.o
 lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o
 
 obj-y += msr.o msr-reg.o msr-reg-export.o
@@ -30,7 +31,6 @@ ifeq ($(CONFIG_X86_32),y)
         lib-y += atomic64_cx8_32.o
         lib-y += checksum_32.o
         lib-y += strstr_32.o
-        lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += semaphore_32.o
         lib-y += string_32.o
         lib-y += cmpxchg.o
 ifneq ($(CONFIG_X86_CMPXCHG64),y)
@@ -43,6 +43,5 @@ else
         lib-y += thunk_64.o clear_page_64.o copy_page_64.o
         lib-y += memmove_64.o memset_64.o
         lib-y += copy_user_64.o copy_user_nocache_64.o
-	lib-$(CONFIG_RWSEM_XCHGADD_ALGORITHM) += rwsem_64.o
 	lib-y += cmpxchg16b_emu.o
 endif

arch/x86/lib/rwsem_64.S → arch/x86/lib/rwsem.S

@@ -1,3 +1,50 @@
+/*
+ * 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/dwarf2.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 whish is either a return
+ * value or just clobbered..
+ */
+
+#define save_common_regs \
+	pushl_cfi %ecx; CFI_REL_OFFSET ecx, 0
+
+#define restore_common_regs \
+	popl_cfi %ecx; CFI_RESTORE ecx
+
+	/* Avoid uglifying the argument copying x86-64 needs to do. */
+	.macro movq src, dst
+	.endm
+
+#else
+
 /*
  * x86-64 rwsem wrappers
  *
@@ -16,12 +63,6 @@
  * but %rdi, %rsi, %rcx, %r8-r11 always need saving.
  */
 
-#include <linux/linkage.h>
-#include <asm/rwlock.h>
-#include <asm/alternative-asm.h>
-#include <asm/frame.h>
-#include <asm/dwarf2.h>
-
 #define save_common_regs \
 	pushq_cfi %rdi; CFI_REL_OFFSET rdi, 0; \
 	pushq_cfi %rsi; CFI_REL_OFFSET rsi, 0; \
@@ -40,16 +81,18 @@
 	popq_cfi %rsi; CFI_RESTORE rsi; \
 	popq_cfi %rdi; CFI_RESTORE rdi
 
+#endif
+
 /* Fix up special calling conventions */
 ENTRY(call_rwsem_down_read_failed)
 	CFI_STARTPROC
 	save_common_regs
-	pushq_cfi %rdx
-	CFI_REL_OFFSET rdx, 0
+	__ASM_SIZE(push,_cfi) %__ASM_REG(dx)
+	CFI_REL_OFFSET __ASM_REG(dx), 0
 	movq %rax,%rdi
 	call rwsem_down_read_failed
-	popq_cfi %rdx
-	CFI_RESTORE rdx
+	__ASM_SIZE(pop,_cfi) %__ASM_REG(dx)
+	CFI_RESTORE __ASM_REG(dx)
 	restore_common_regs
 	ret
 	CFI_ENDPROC
@@ -67,7 +110,8 @@ ENDPROC(call_rwsem_down_write_failed)
 
 ENTRY(call_rwsem_wake)
 	CFI_STARTPROC
-	decl %edx	/* do nothing if still outstanding active readers */
+	/* do nothing if still outstanding active readers */
+	__ASM_HALF_SIZE(dec) %__ASM_HALF_REG(dx)
 	jnz 1f
 	save_common_regs
 	movq %rax,%rdi
@@ -77,16 +121,15 @@ ENTRY(call_rwsem_wake)
 	CFI_ENDPROC
 ENDPROC(call_rwsem_wake)
 
-/* Fix up special calling conventions */
 ENTRY(call_rwsem_downgrade_wake)
 	CFI_STARTPROC
 	save_common_regs
-	pushq_cfi %rdx
-	CFI_REL_OFFSET rdx, 0
+	__ASM_SIZE(push,_cfi) %__ASM_REG(dx)
+	CFI_REL_OFFSET __ASM_REG(dx), 0
 	movq %rax,%rdi
 	call rwsem_downgrade_wake
-	popq_cfi %rdx
-	CFI_RESTORE rdx
+	__ASM_SIZE(pop,_cfi) %__ASM_REG(dx)
+	CFI_RESTORE __ASM_REG(dx)
 	restore_common_regs
 	ret
 	CFI_ENDPROC