[PATCH] i386: Redo semaphore and rwlock assembly helpers
- Move them to a pure assembly file. Previously they were in
a C file that only consisted of inline assembly. Doing it in pure
assembler is much nicer.
- Add a frame.i include with FRAME/ENDFRAME macros to easily
add frame pointers to assembly functions
- Add dwarf2 annotation to them so that the new dwarf2 unwinder
doesn't get stuck on them
- Random cleanups
Includes feedback from Jan Beulich and a UML build fix from Andrew
Morton.
Cc: jbeulich@novell.com
Cc: jdike@addtoit.com
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/arch/i386/lib/semaphore.S b/arch/i386/lib/semaphore.S
new file mode 100644
index 0000000..e16ff16
--- /dev/null
+++ b/arch/i386/lib/semaphore.S
@@ -0,0 +1,154 @@
+/*
+ * i386 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/config.h>
+#include <linux/linkage.h>
+#include <asm/rwlock.h>
+#include <asm/alternative-asm.i>
+#include <asm/frame.i>
+#include <asm/dwarf2.h>
+
+/*
+ * 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..
+ */
+ .section .sched.text
+ENTRY(__down_failed)
+ CFI_STARTPROC
+ FRAME
+ pushl %edx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET edx,0
+ pushl %ecx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET ecx,0
+ call __down
+ popl %ecx
+ CFI_ADJUST_CFA_OFFSET -4
+ CFI_RESTORE ecx
+ popl %edx
+ CFI_ADJUST_CFA_OFFSET -4
+ CFI_RESTORE edx
+ ENDFRAME
+ ret
+ CFI_ENDPROC
+ END(__down_failed)
+
+ENTRY(__down_failed_interruptible)
+ CFI_STARTPROC
+ FRAME
+ pushl %edx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET edx,0
+ pushl %ecx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET ecx,0
+ call __down_interruptible
+ popl %ecx
+ CFI_ADJUST_CFA_OFFSET -4
+ CFI_RESTORE ecx
+ popl %edx
+ CFI_ADJUST_CFA_OFFSET -4
+ CFI_RESTORE edx
+ ENDFRAME
+ ret
+ CFI_ENDPROC
+ END(__down_failed_interruptible)
+
+ENTRY(__down_failed_trylock)
+ CFI_STARTPROC
+ FRAME
+ pushl %edx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET edx,0
+ pushl %ecx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET ecx,0
+ call __down_trylock
+ popl %ecx
+ CFI_ADJUST_CFA_OFFSET -4
+ CFI_RESTORE ecx
+ popl %edx
+ CFI_ADJUST_CFA_OFFSET -4
+ CFI_RESTORE edx
+ ENDFRAME
+ ret
+ CFI_ENDPROC
+ END(__down_failed_trylock)
+
+ENTRY(__up_wakeup)
+ CFI_STARTPROC
+ FRAME
+ pushl %edx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET edx,0
+ pushl %ecx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET ecx,0
+ call __up
+ popl %ecx
+ CFI_ADJUST_CFA_OFFSET -4
+ CFI_RESTORE ecx
+ popl %edx
+ CFI_ADJUST_CFA_OFFSET -4
+ CFI_RESTORE edx
+ ENDFRAME
+ ret
+ CFI_ENDPROC
+ END(__up_wakeup)
+
+/*
+ * rw spinlock fallbacks
+ */
+#ifdef CONFIG_SMP
+ENTRY(__write_lock_failed)
+ CFI_STARTPROC simple
+ 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
+ END(__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
+ END(__read_lock_failed)
+
+#endif