From: Christoph Lameter <clameter@sgi.com>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org,
Rusty Russell <rusty@rustcorp.com.au>, Andi Kleen <ak@suse.de>
Subject: [patch 07/14] percpu: Make the asm-generic/percpu.h more generic
Date: Mon, 26 Nov 2007 16:14:14 -0800 [thread overview]
Message-ID: <20071127001430.771249261@sgi.com> (raw)
In-Reply-To: 20071127001407.859743255@sgi.com
[-- Attachment #1: genericize-percpu.h --]
[-- Type: text/plain, Size: 4008 bytes --]
Add the ability to use generic/percpu even if the arch needs to override
several aspects of its operations. This will enable the use of generic
percpu.h for all arches.
An arch may define:
__per_cpu_offset Do not use the generic pointer array. Arch must
define per_cpu_offset(cpu) (used by x86_64, s390).
__my_cpu_offset Can be defined to provide an optimized way to determine
the offset for variables of the currently executing
processor. Used by ia64, x86_64, x86_32, sparc64, s/390.
SHIFT_PTR(ptr, offset) If an arch defines it then special handling
of pointer arithmentic may be implemented. Used
by s/390.
(Some of these special percpu arch implementations may be later consolidated
so that there are less cases to deal with.)
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
---
include/asm-generic/percpu.h | 64 +++++++++++++++++++++++++++++++++++--------
1 file changed, 53 insertions(+), 11 deletions(-)
Index: linux-2.6/include/asm-generic/percpu.h
===================================================================
--- linux-2.6.orig/include/asm-generic/percpu.h 2007-11-24 19:33:55.416103196 -0800
+++ linux-2.6/include/asm-generic/percpu.h 2007-11-24 19:36:35.016350539 -0800
@@ -3,27 +3,69 @@
#include <linux/compiler.h>
#include <linux/threads.h>
+/*
+ * Determine the real variable name from the name visible in the
+ * kernel sources.
+ */
+#define per_cpu_var(var) per_cpu__##var
+
#ifdef CONFIG_SMP
+/*
+ * per_cpu_offset() is the offset that has to be added to a
+ * percpu variable to get to the instance for a certain processor.
+ *
+ * Most arches use the __per_cpu_offset array for those offsets but
+ * some arches have their own ways of determining the offset (x86_64, s390).
+ */
+#ifndef __per_cpu_offset
extern unsigned long __per_cpu_offset[NR_CPUS];
-
#define per_cpu_offset(x) (__per_cpu_offset[x])
+#endif
-/* var is in discarded region: offset to particular copy we want */
-#define per_cpu(var, cpu) (*({ \
- extern int simple_identifier_##var(void); \
- RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]); }))
-#define __get_cpu_var(var) per_cpu(var, smp_processor_id())
-#define __raw_get_cpu_var(var) per_cpu(var, raw_smp_processor_id())
+/*
+ * Determine the offset for the currently active processor.
+ * An arch may define __my_cpu_offset to provide a more effective
+ * means of obtaining the offset to the per cpu variables of the
+ * current processor.
+ */
+#ifndef __my_cpu_offset
+#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id())
+#define my_cpu_offset per_cpu_offset(smp_processor_id())
+#else
+#define my_cpu_offset __my_cpu_offset
+#endif
+
+/*
+ * Add a offset to a pointer but keep the pointer as is.
+ *
+ * Only S390 provides its own means of moving the pointer.
+ */
+#ifndef SHIFT_PTR
+#define SHIFT_PTR(__p, __offset) RELOC_HIDE((__p), (__offset))
+#endif
+
+/*
+ * A percpu variable may point to a discarded reghions. The following are
+ * established ways to produce a usable pointer from the percpu variable
+ * offset.
+ */
+#define per_cpu(var, cpu) (*SHIFT_PTR(&per_cpu_var(var), per_cpu_offset(cpu)))
+#define __get_cpu_var(var) (*SHIFT_PTR(&per_cpu_var(var), my_cpu_offset))
+#define __raw_get_cpu_var(var) (*SHIFT_PTR(&per_cpu_var(var), __my_cpu_offset))
+
+#ifdef CONFIG_ARCH_SETS_UP_PER_CPU_AREA
+extern void setup_per_cpu_areas(void);
+#endif
#else /* ! SMP */
-#define per_cpu(var, cpu) (*((void)(cpu), &per_cpu__##var))
-#define __get_cpu_var(var) per_cpu__##var
-#define __raw_get_cpu_var(var) per_cpu__##var
+#define per_cpu(var, cpu) (*((void)(cpu), &per_cpu_var(var)))
+#define __get_cpu_var(var) per_cpu_var(var)
+#define __raw_get_cpu_var(var) per_cpu_var(var)
#endif /* SMP */
-#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name
+#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu_var(name)
#endif /* _ASM_GENERIC_PERCPU_H_ */
--
next prev parent reply other threads:[~2007-11-27 0:18 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-27 0:14 [patch 00/14] Per cpu code simplification Christoph Lameter
2007-11-27 0:14 ` [patch 01/14] Modules: Handle symbols that have a zero value Christoph Lameter
2007-11-27 0:14 ` [patch 02/14] Modules: Include sections.h to avoid defining linker variables explicitly Christoph Lameter
2007-11-27 0:14 ` [patch 03/14] Modules: Fold percpu_modcopy into module.c and get rid of the macro from hell Christoph Lameter
2007-11-27 0:14 ` [patch 04/14] ia64: Remove the __SMALL_ADDR_AREA attribute for per cpu access Christoph Lameter
2007-11-27 5:20 ` David Mosberger-Tang
2007-11-27 18:15 ` Christoph Lameter
2007-11-27 21:10 ` David Mosberger-Tang
2007-11-27 21:18 ` Christoph Lameter
2007-11-27 21:27 ` David Mosberger-Tang
2007-11-27 22:02 ` Christoph Lameter
2007-11-27 9:30 ` Andreas Schwab
2007-11-27 18:17 ` Christoph Lameter
2007-11-27 21:24 ` Andreas Schwab
2007-11-27 21:38 ` Christoph Lameter
2007-11-27 22:14 ` Adrian Bunk
2007-11-27 0:14 ` [patch 05/14] percpu: Use a Kconfig variable to configure arch specific percpu setup Christoph Lameter
2007-11-27 4:30 ` Rusty Russell
2007-11-27 18:14 ` Christoph Lameter
2007-11-28 1:36 ` Rusty Russell
2007-11-28 18:51 ` Christoph Lameter
2007-11-28 23:17 ` Rusty Russell
2007-11-28 23:36 ` Christoph Lameter
2007-11-30 2:23 ` Rusty Russell
2007-11-28 23:45 ` Jeremy Fitzhardinge
2007-11-29 0:11 ` Christoph Lameter
2007-11-29 1:18 ` Andi Kleen
2007-11-29 1:27 ` Christoph Lameter
2007-11-29 1:30 ` Jeremy Fitzhardinge
2007-11-29 1:32 ` Andi Kleen
2007-11-29 1:35 ` Christoph Lameter
2007-11-29 1:42 ` Jeremy Fitzhardinge
2007-11-29 1:48 ` Christoph Lameter
2007-11-29 1:54 ` Jeremy Fitzhardinge
2007-11-29 2:06 ` Christoph Lameter
2007-11-29 5:29 ` Jeremy Fitzhardinge
2007-11-29 6:08 ` Christoph Lameter
2007-11-29 6:10 ` Christoph Lameter
2007-11-27 23:40 ` Randy Dunlap
2007-11-28 0:03 ` Christoph Lameter
2007-11-28 0:05 ` Randy Dunlap
2007-11-27 0:14 ` [patch 06/14] percpu: Move arch XX_PER_CPU_XX definitions into linux/percpu.h Christoph Lameter
2007-11-27 0:14 ` Christoph Lameter [this message]
2007-11-27 0:14 ` [patch 08/14] x86_32: Use generic percpu.h Christoph Lameter
2007-11-27 0:14 ` [patch 09/14] x86_64: Use generic percpu Christoph Lameter
2007-11-27 0:14 ` [patch 10/14] s390: " Christoph Lameter
2007-11-27 0:14 ` [patch 11/14] Powerpc: Use generic per cpu Christoph Lameter
2007-11-27 7:41 ` Kumar Gala
2007-11-27 18:16 ` Christoph Lameter
2007-11-27 20:58 ` Paul Mackerras
2007-11-27 21:13 ` Christoph Lameter
2007-11-28 2:35 ` Paul Mackerras
2007-11-28 18:54 ` Christoph Lameter
2007-12-02 20:55 ` Benjamin Herrenschmidt
2007-11-27 0:14 ` [patch 12/14] Sparc64: Use generic percpu Christoph Lameter
2007-11-27 0:14 ` [patch 13/14] ia64: " Christoph Lameter
2007-11-27 1:37 ` Christoph Lameter
2007-11-27 0:14 ` [patch 14/14] x86: Unify percpu.h Christoph Lameter
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