[patch 41/41] x86_64: Support for cpu ops

Christoph Lameter
2008-05-30T04:11:25Z

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Support fast cpu ops in x86_64 by providing a series of functions that
generate the proper instructions.

Define CONFIG_HAVE_CPU_OPS so that core code
can exploit the availability of fast per cpu operations.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
arch/x86/Kconfig | 4 ++++
include/asm-x86/percpu.h | 31 +++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)

Index: linux-2.6/arch/x86/Kconfig
===================================================================
--- linux-2.6.orig/arch/x86/Kconfig 2008-05-29 18:05:08.514214613 -0700
+++ linux-2.6/arch/x86/Kconfig 2008-05-29 18:09:55.889464792 -0700
@@ -168,6 +168,10 @@ config GENERIC_PENDING_IRQ
depends on GENERIC_HARDIRQS && SMP
default y

+config HAVE_CPU_OPS
+ bool
+ default y
+
config X86_SMP
bool
depends on SMP && ((X86_32 && !X86_VOYAGER) || X86_64)
Index: linux-2.6/include/asm-x86/percpu.h
===================================================================
--- linux-2.6.orig/include/asm-x86/percpu.h 2008-05-29 18:08:28.513214585 -0700
+++ linux-2.6/include/asm-x86/percpu.h 2008-05-29 18:09:55.889464792 -0700
@@ -196,5 +196,36 @@ do { \
#define x86_cmpxchg_percpu(var, old, new) \
percpu_cmpxchg_op(per_cpu_var(var), old, new)

+#define CPU_READ(obj) percpu_from_op("mov", obj)
+#define CPU_WRITE(obj, val) percpu_to_op("mov", obj, val)
+#define CPU_ADD(obj, val) percpu_to_op("add", obj, val)
+#define CPU_SUB(obj, val) percpu_to_op("sub", obj, val)
+#define CPU_INC(obj) percpu_addr_op("inc", obj)
+#define CPU_DEC(obj) percpu_addr_op("dec", obj)
+#define CPU_XCHG(obj, val) percpu_to_op("xchg", var, val)
+#define CPU_CMPXCHG(obj, old, new) percpu_cmpxchg_op(var, old, new)
+
+/*
+ * All cpu operations are interrupt safe and do not need to disable
+ * preempt. So the other variants all reduce to the same instruction.
+ */
+#define _CPU_READ CPU_READ
+#define _CPU_WRITE CPU_WRITE
+#define _CPU_ADD CPU_ADD
+#define _CPU_SUB CPU_SUB
+#define _CPU_INC CPU_INC
+#define _CPU_DEC CPU_DEC
+#define _CPU_XCHG CPU_XCHG
+#define _CPU_CMPXCHG CPU_CMPXCHG
+
+#define __CPU_READ CPU_READ
+#define __CPU_WRITE CPU_WRITE
+#define __CPU_ADD CPU_ADD
+#define __CPU_SUB CPU_SUB
+#define __CPU_INC CPU_INC
+#define __CPU_DEC CPU_DEC
+#define __CPU_XCHG CPU_XCHG
+#define __CPU_CMPXCHG CPU_CMPXCHG
+
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_PERCPU_H_ */

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